Development and Validation of 3-Dimensional Tractive Force Measuring Instrument under High-Velocity Flow Conditions

김민규 인제대학교 일반대학원 2021 국내박사

Tractive force is a crucial element in the river structure design and can be indirectly evaluated using a theoretical equation by measuring hydraulic elements. The theoretical equation is applicable when the flow type is steady and uniform; however, its application is not easy because it requires the measurement of turbulent terms in the flow direction and in both the lateral and vertical direction of the flow. Moreover, it requires the mean flow velocity and the mean value of the cross section of the flow for the calculation. Thus, deviations in local tractive force increase significantly according to the channel geometry and flow velocity distribution. River structures are carried away or destroyed by the local tractive force generated by high-velocity flow (Fr > 1) rather than low-velocity flow (Fr < 1). Thus, a tractive force measuring instrument that can directly measure local tractive force in a stable manner in low- and high-velocity flow is required. In this study, a 3-dimensional tractive force measuring instrument that can directly measure local tractive force at the river bed was developed. The instrument can directly measure tractive forces in the flow direction (X) and in the lateral direction of the flow (Y) as well as the ±pressure in the flow vertical direction (Z) in a stable manner even at low and high flow velocities. To verify the performance of the developed 3-dimensional tractive force measuring instrument, it was installed in an orifice type fixed bed open channel, and the tractive force was directly measured and analyzed in the velocity flow, Reynolds number, and Froude number ranges of 0.622–3.604 m/s , 33,756–188,285, and 0.646–4.217, respectively. The performance of the instrument was verified by comparing the tractive force values directly measured through hydraulic experiments with those calculated using the existing theoretical equation. In addition, the Reynolds stress and flow velocity of the same flow were measured using a particle image velocimetry (PIV) system. The results of directly measuring the tractive force using the 3-dimensional tractive force measuring instrument are as follows. The tractive force measured in the flow direction increased in the form of a quadratic function graph as the Froude number increased and that measured in the lateral direction of the flow was close to zero. The plus (+) and minus (-) signs of the measurements in the lateral direction are vibrations that indicate the direction, and the value of zero implies that movements to the left and right are similar. The absolute values of the measurement data in the lateral direction represent the absolute sizes of the data. When the trend line of the average absolute value of the tractive force measured in the lateral direction was analyzed, it was found to linearly increase as the Froude number increased. Therefore, as the Froude number increased, the size of movements to the left and right also increased. This indicates that the tractive force in the lateral direction of the flow also affects the scour and erosion of the river bed material. The tractive force directly measured using the 3-dimensional tractive force measuring instrument fell in the range of the tractive force that considered the Manning formula, and it also exhibited a range according to the Froude number. The tractive force had a range because the feed flow rate, flow velocity, and cross-sectional area of the flow in the channel were different depending on the experimental case. The Reynolds stress measured through PIV showed a larger range compared to other measurement methods, and it exhibited an error rate of approximately 30% with the measured tractive force value. Because the tractive force that considered the Manning formula is proportional to the n-th power of the roughness coefficient, the error of the calculated tractive force becomes large owing to the roughness coefficient error. Therefore, the roughness coefficient was inversely calculated with the tractive force directly measured using the 3-dimensional tractive force measuring instrument, and the results were found to be 0.0165 and 0.0097 for subcritical and supercritical flows, respectively. According to Lee et al. (2010), the roughness coefficient decreases as the flow rate increases in an actual river. The results of this study also showed that the roughness coefficient decreased as the flow rate in the experimental channel increased. Assuming that the suction phenomenon occurs in high-velocity flow owing to the pressure difference caused by the rapid water surface change, a pressure gauge (Z) was installed in the 3-dimensional tractive force measuring instrument, and the measurement results were as follows. In most experimental cases, the pressure head was measured to be approximately 10% higher than the water depth of the channel. When the standard deviation of the measurement data was analyzed, fluctuations in the measured bed pressure were found to be larger than those in the measured water depth as the Froude number increased. Further research is required to establish whether channel vibration was caused by the high-velocity flow or the actual bed pressure was high. As the developed 3-dimensional tractive force measuring instrument well reflected the roughness coefficient and hydraulic characteristics, the tractive force and bed pressure in the flow direction and in the lateral direction of the flow were measured in real time. Based on this, it is necessary to directly measure local tractive forces. It is presumed that the tractive force data directly measured in a fixed channel can be utilized in the numerical analysis correction procedure. If the shear plate of the 3-dimensional tractive force measuring instrument is produced to have a roughness similar to that of the river bed material, the tractive force at the bottom of an actual river can be directly measured. Based on the tractive force measured using the measuring instrument, one can inversely estimate the roughness coefficient, flow velocity, and flow rate, as well as evaluate the allowable and critical tractive forces of the installed material. The developed 3-dimensional tractive force measuring instrument can evaluate not only the single material at a laboratory scale but also the critical tractive force of river bed structures (e.g., revetments, river bed protection, and gabions) when installed at an actual site.

Measuring "Well": Clinical Measuring Practices and Philosophy of Measurement

Jackson, Rebecca L Indiana University ProQuest Dissertations & Theses 2023 해외박사(DDOD)

This dissertation examines three successful, patient-centric measuring practices in the Anglo-American clinical context, spanning from the early 19th century to today: (1) the use of "drops" as a fluid unit in medicine and pharmacy, (2) the measurement of cervical dilation by hand (digital cervimetry) for labor assessment, and (3) the Apgar Score for newborn health assessment. I also briefly introduce a discussion of (4) the Patient Generated Index (PGI) and the Schedule for Evaluation of Individualized Quality of Life (SEIQoL) for measuring patient status and outcomes. All four practices were developed to ensure preferable patient outcomes, at the expense of precisely representing empirical states. A better understanding of the "non-standard" clinical measuring practices of the 19th and 20th centuries shows that the ethical-epistemic challenge of having both "patient-centric" and "evidence-based" measurement has a much longer history than the recent emergence of these terms would suggest. I discuss the ethical and epistemic challenges which had to be overcome when validating these measures, and consider how the successful (and failed) endeavors of past practitioners can inform methodological issues faced in the formation of clinical indexes today. I introduce the notion of "epistemic audiences," and argue that units (and accompanying scales) of measurement serve as "epistemic conduits" for these audiences, transforming observations into difference-making data toward relevant judgments and/or actions. By examining the ways that these non-standard measuring practices challenge dominant theoretical frameworks in philosophy of measurement, I form recommendations for how we can improve philosophy of measurement to better account for the historical success of these practices: (1) the scope of philosophy of measurement should expand to encompass entire measuring practices; (2) measurement success should be understood "ecologically," as being fit within a "niche" of pragmatic, physical, and temporal constraints and demands; and (3) the "problem of coordination" should be extended to include the relevant set of judgments (the landscape of decision-making at hand), in order to move towards a clinically relevant philosophy of measurement.

Measuring the Inequality of Opportunity Using Individual-Level Advantage

Stevens, David Henry University of California, Berkeley ProQuest Disser 2024 해외박사(DDOD)

Educational inequality has primarily been defined and measured as group-centered differences in achievement. Often described using the achievement-gap framework, a substantial portion of the literature has highlighted the pervasive inequalities in educational outcomes among ethnic-racial groups or by socioeconomic status. The focus on group-level disparities in achievement has yielded important insights into systematic inequalities and informed policies at both the state and national level, including the No Child Left Behind Act, Every Student Succeeds Act, and California’s Local Control Funding Formula. Despite this, the achievement-gap framework has been criticized for (a) reinforcing stereotypes, (b) essentializing students based on group membership and ignoring their multiple identities, (c) disregarding within-group heterogeneity, (d) frequently omitting groups with fewer members, and (e) positioning White or middle class as the norm. Alternatively, some scholars have suggested that research on educational inequality should focus instead on gaps in opportunity as the precursors to group-based differences in achievement.Although reframing achievement gaps as opportunity gaps provides a different perspective, by focusing at the group level, this approach remains vulnerable to many of the same concerns as the achievement-gap framework, both of which lack student-level specificity. Importantly, although there is general agreement regarding the measurement of achievement, the measurement of opportunity is beset by a number of challenges, most prominently by the lack of a commonly shared definition, an essential factor for its application in policy and practice. In this dissertation, I proposed and tested the Advantage framework as a potential solution to the weaknesses and limitations of the gap frameworks for measuring inequality of opportunity and evaluating achievement.I had three requirements when developing the Advantage framework. These included that the model should (a) include all students, (b) embrace the complexity of students’ multiple overlapping group memberships, and (c) yield individual-level measures. I built upon the method demonstrated by Ferreira and Gignoux (2013) in which they measured the inequality of opportunity using the variance in achievement explained by students’ background characteristics. Whereas their method yielded overall sample-level measures of inequality, I provided each student with an individual-level measure of advantage, defined by the Cambridge dictionary as the conditions giving greater chance of success. As an individual-level continuous measure, Advantage explained the inequality of opportunity at multiple levels including at the population level, among and within groups, and even between two individuals.In the first study, I proposed and evaluated the framework for defining and measuring opportunity based on individual-level Advantage, estimated using six educationally relevant demographic variables and aggregated using students’ demographic profiles. I evaluated the Advantage framework using data from two school districts, multiple academic years, and over a range of outcomes. Advantage was found reliable and valid across both districts. Compared to the ethnic-racial and socioeconomic achievement-gap frameworks, Advantage explained up to 4.5 times more of the variance in achievement, suggesting that group-centered methods may significantly understate the actual magnitude of educational inequality. Advantage explained up to 44% of the heterogeneity of achievement seen within ethnic-racial groups and up to 38% within socioeconomic groups. Advantage correctly classified proficiency status on a standardized assessment for over 80% of the students and came with significantly lower false positive and false negative rates, an important characteristic for practitioners working to address inequality. Controlling for Advantage eliminated gaps in proficiency between ethnic-racial and socioeconomic groups on standardized assessments in one district, and largely so in the other. This study suggested that the Advantage framework is a valid and reliable method for measuring the inequality of opportunity.In the second study, I used the Advantage framework to examine longitudinal data. Students exposed to greater educational opportunities prior to starting school typically demonstrate higher initial achievement and grow at faster rates compared to their less advantaged peers. The inequalities in opportunity prior to starting school frequently translate into inequalities in achievement in the later grades. In this study, I compared two methods for translating student demographics into indicators of inequality: California’s Local Control Funding Formula (LCFF) and the Advantage framework. Whereas the LCFF dichotomizes inequality into two categories, Advantage generates individual-level measures along a continuum. I applied the two methods to longitudinal achievement data from two school districts and compared the extent to which the models explained students’ initial and long-term achievement. Compared to the LCFF, the Advantage framework explained up to 3.3 times more of the variance in Grade 3 achievement, up to 3.4 times more of the variance in growth, and was between 7.5% and 9% more accurate in predicting proficiency on standardized assessments. Although both models demonstrated evidence for the Matthew effect, the Advantage framework better portrayed it as a heterogenous phenomenon. Based on the findings of this study, the Advantage framework could improve policies designed to mitigate educational inequality.For the third study, I applied the Advantage framework at the school-level. In 2013, California implemented the Local Control Funding Formula to reduce inequalities in both educational achievement and opportunity. In this study, I used hierarchical linear modeling to examine the inequality of opportunity in California’s over 9,000 public schools from 2015–2024 with a specific emphasis on the time periods pre- and post-COVID. I used the Advantage framework to calculate school-specific measures of Advantage using a combination of demographic, enrollment, and test data. School-level measures of Advantage were then used to measure the inequality of opportunity in both cross-sectional and longitudinal analyses. Results showed that as achievement was increasing during the years pre-COVID, the inequality of opportunity was decreasing, suggesting that raising test scores and reducing inequality can work in tandem. Due to the COVID interruption in learning, inequality increased and achievement declined substantially from 2019–2022, but the positive trends resumed between 2022–2024. Compared to pre-COVID, school-level Advantage explained 95% more of the variance in test scores for math post-COVID and 32% more for English language arts, indicating school-level characteristics played a more prominent role in the post-pandemic recovery.

복합형상 하이브리드 측정기의 제작 및 성능평가

이영호 창원대학교 2017 국내석사

Abstract and Key words Fabrication and Performance Evaluation of Composite Hybrid Measuring Instrument by Lee Youngho Dept. of Industrial and Mechanical Engineering Graduate School of Engineering Changwon National University Two types of measuring device that are currently on the market include instruments for shape measurement and roundness measurement. As such equipment can range in price from tens of millions of won to more than 200 million won, it is often too costly for small businesses or individuals to purchase. Therefore, in order to integrate shape measurement and roundness measurement into a single device, this study aimed to reduce trial and error by 3D modeling and simulation, and confirm the feasibility of operation. Based on these outcomes, a prototype for a hybrid measuring instrument was fabricated. As a result of performance evaluation and comparative evaluation, we verified the feasibility of implementation and application of the hybrid measuring instrument. Keywords Hybrid Measuring Instrument, Roundness Accuracy, Shape Accuracy, 3D modeling, Performance Evaluation 현재 시중에서 판매되고 있는 고가의 측정기는 형상 측정기와 진원도 측정기가 있다. 각각 수 천 만원에서 많게는 2억 원 사이의 매우 고가의 장비이기 때문에 소규모의 기업이나 개인이 구매하여 사용하기에는 경제적 부담이 따르게 된다. 따라서 본 연구에서는 형상 측정기와 진원도 측정기를 하나의 이송장치로 통합하기 위해 2D구조 설계로 기초 분석을 한 후 3D모델링과 시뮬레이션을 진행하여 제작 시 발생되는 시행착오를 줄이고 구동가능성을 확인 하였다. 이와 같은 결과를 바탕으로 복합 형상 하이브리드 측정기의 시제품을 제작 하였다. 또한 성능평가 및 측정 성능 비교 평가를 진행한 결과 복합 형상 하이브리드 측정기의 구현 및 활용 가능성을 검증 하였다.

形狀測定器의 檢出部機構設計에 關한 硏究

김수강 漢陽大學校 産業經營大學院 1979 국내석사

지방공공서비스의 효율성에 관한 연구 : 공급방식과 영향요인을 중심으로

안병윤 연세대학교 대학원 2021 국내박사

This paper was studied with the aim of measuring the efficiency of public services in local governments to determine whether efficient supply methods exist depending on the type of public service and what factors affect efficiency. The question of the efficiency of local public services in this study consists of two. The first question is 'Is there an efficient supply method depending on the type of local public service?' and the second question is 'What factors affect efficiency and are they working properly?' First, to identify the first question, local public services were classified into four types according to two criteria: the degree of publicity and the ease of measuring performance. Type I is a public service that is highly public and difficult to measure performance, and includes water supply service and public library service. Type II is a service that is highly public but easy to measure performance, and includes sewage disposal services and waste collection services. Type is a service Ⅲ with low public nature but high difficulty in measuring performance, and includes culture and art center operation and youth training center service. Finally, public parking lot operation and recreational forest service were selected as the service of "Type Ⅳ" with low difficulty in both public nature and performance measurement. For the purpose of analyzing efficiency by local public service and comparing efficiency by supply method, data envelopment analysis (DEA) was used to analyze efficiency in the public sector. In the next phase 2, I validate the factors affecting efficiency by using the efficiency values analyzed in phase I as dependent variables. To validate the factors of influence, I hypothesize and analyze Panel-Tobit Regression with 13 specific variables, taking into account financial, political, and regional characteristics. Financial characteristics include per capita local tax, per capita property tax, financial independence and debt ratio. The political characteristics include the number of terms of the heads of local governments, regime change, election votes for the heads of local governments, voter turnout for local elections, and the agreement between the heads of local governments and parliament. Finally, regional characteristics include population size, population density, area, and urbanization rates. The study involves 227 local governments nationwide, with a time span of 10 years from 2009 to 2018. The summary of the research results is as follows. First, the efficiency of local public services in our country has been shown to be very low. The technology efficiency (CRS) average is 0.51, the operational efficiency (VRS) average is 0.64 and the scale efficiency (SE) average is 0.80, with inefficiencies of 49%, 36%, and 20%, respectively. Based on the technology efficiency (CRS) of each individual public service, waste collectionservices operate most efficiently with an efficiency value of 0.76, followed by recreational forest service 0.58, public parking lot operation 0.57 and water supply service 0.56. The operation of the public library, sewage disposal, culture and art center, and youth training center show low efficiency of 0.44 levels. As a cause of inefficiency, operational inefficiency, which is pure technology efficiency, is found to be the main cause of public service inefficiency. Therefore, it is necessary to introduce the latest production technologies and facilities, redesign the work process, strengthen the efficiency of personnel and organizational operations, and enhance the appropriateness of financial investment. In terms of scale efficiency, most local governments or public service DMUs are produced in the IRS section, which is analyzed to be the cause of inefficiency. In view of the nature of the service, it is necessary to find a variety of supply methods to increase the size of the supply. As a result of analyzing the efficiency of each supply method of local public services, the provision by local government shows high efficiency in water supply service, culture and arts center operation, and youth training center service. Public provision is highly efficient in sewage disposal services and waste collection services. Private provision by contracting out shows efficiency in the operation of public libraries, public parking lots, and recreation forest service. Looking at the efficient supply method by service type, In the case of "Type I", a public service that is highly public and relatively difficult to measure performance, the water supply service is excellent in the provision by local government, but the public library service is excellent in the private provision by contracting out. In Type II, which is highly public and relatively easy to measure performance, both sewage disposal services and waste collection services show the best results of public provision. In the service of "Type ", which Ⅲ is classified as a low public service but difficult to measure performance, both culture and arts center services and youth training center services are efficient in the provsion by local government. Both the public parking lot service and the recreational forest service, which are low public nature and easy to measure performance, are highly efficient in private provision methods. Panel-Tobit Regression Analysis of Influencers shows that financial, political, and local variables all play a significant role as influencers in the efficiency of local public services. Financial variables have been tested to have a significant impact on the efficiency of all public services except public parking lots. The local tax per person cites the hypothesis as being meaningful in terms of the technological efficiency of water supply and the operational efficiency of waste collection service, but is negative in culture and arts centers, public librariy service, and recreational forest services. Although the degree of financial independence is significant in the operation of recreational forest service, it cites hypotheses as it shows the significance of justice in the operation of water supply, publc library operation, collection of household waste, and the operation of culture and art centers and youth training centers. Property taxes per person shows positive significance in sewage disposal and waste collection, but negative significance in recreational forest service. The debt ratio showes a significant negative relationship only in the operation of water supply, which do not have a significant impact on efficiency. Among the financial variables, financial independence is shown to have a significant effect on the efficiency of the most public services, citing hypotheses. Political influences have been tested to have a significant impact on the efficiency of public services, excluding waste collection and public parking lots. The vote for the head of a local government shows positive significance in water supply service, but rejects the hypothesis because it shows negative significance in the operation of the culture and arts center and sewage disposal services. Turnout in local elections is only significant in the water supply, but the hypothesis was rejected. The agreement between the heads of local governments' parties and the majority of the parliament show the significance of the plus in the culture and arts center, and the negative significance in sewage disposal services. Regional regime change is consistent with the hypothesis of positive significance in water supply and the culture and arts center. The term of office of the head of a local government shows the positive significance in sewerage disposal services and negative in recreational forest service, which works the opposite way. Regional factors of influence have been tested to have a significant impact on the efficiency of all public services subject to analysis. The area has negative significance in the operation of water supply services, sewage disposal services, public parking lots and recreational forest service, and has positive significance only in waste collection service. The population size shows positive significance for the technological efficiency of the operation of public libraries, culture and art centers, waste collection, and youth training centers. The population density is expected to serve as a mechanism for increasing efficiency in the supply and demand of services due to its large population residing in a small area, but it is only the culture and art center and youth training center operating services that shows a clear positive relationship. The policy implications of the study are that the efficiency of public services of local governments in Korea is very low, and it is urgent to come up with measures to improve service efficiency. First of all, the introduction of private provision methods by contracting out on the premise of the efficiency of private consignment, as argued in the New Public Management Theory, should be reconsidered in relation to supply methods. In public services that are highly public and difficult to measure performance, the provision by local government is found to be more efficient than private consignment methods. In addition, it is necessary to improve the operation of the private provision by contracting out of local public services in Korea. In order to succeed in entrusting the private sector, moral hazard of the trustee shall be prevented by securing competitiveness in the market and determining renewal of the contract through systematic management supervision and evaluation. The second is that it is necessary to introduce new methods such as consignment production or joint production among local governments, beyond the existing supply methods: provision by local government, public provision, private provision by contracting out. In this study, except for water supply, all public services subject to analysis are supplied in the IRS section, which can increase efficiency if the production scale is expanded. In order to expand the size of production, a new method of joint production or consignment production between local governments is needed. The third implication is that local politics, such as local elections, should be improved to help improve the efficiency of public services, along with improving the autonomy and accountability of local finance operations of local governments. According to the results of the study, it is difficult for the nation's local finance operations and local elections to work to increase the efficiency of local public services. The significance of this work is in theory an attempt at new typification of local public services and in methodology a big data analysis. Few examples of new attempts at public service types and analysis of 10 years of big data on multiple public services are found in existing studies. Furthermore, the results of these big data analyses demonstrate existing theories or arguments about differences in the efficiency of supply methods according to the characteristics of public services. Waterworks, sewage disposal, and domestic waste disposal, which are highly publicized services, are found to be highly efficient in direct management, consistent with Levin & Tadelis (2010)'s study to minimize responsibility and criticism for service failures. In addition, Brown & Potoski (2003)'s study shows that performance-measuring public services such as Culture and Arts Center and Youth Training Center services are both efficient to operate directly. On the other hand, most of the big data used in this study used existing publicly verified data, but there were many missing values and low reliability data. To increase the reliability of the research, I tried to verify it as much as possible, but there was a limit. Inevitably accompanying problems in studies dealing with many data, but in subsequent studies, measures to increase the accuracy of variables should be considered together. In addition, there is a limit to approaching efficiency only in quantitative terms with respect to measuring the efficiency of local public services. The performance of local public services is not only considered in terms of quantity, but quality issues such as service satisfaction are also important. In subsequent studies, it is highly necessary to analyze the efficiency of local public services by considering them together. 이 논문은 지방자치단체의 공공서비스의 효율성 정도를 측정하여 공공서비스 유형에 따라 효율성이 높은 공급방식이 존재하는지와 효율성에 영향을 미치는 요인들이 무엇인지 규명하기 위한 목적에서 연구되었다. 이 연구에서 지방공공서비스의 효율성에 관한 연구 질문은 두 가지로 구성된다. 첫째는 ‘지방공공서비스 유형에 따라 효율성이 높은 공급방식이 있는가?’이며, 둘째는 ‘효율성에 영향을 미치는 요인들은 무엇이고 제대로 작동하고 있는가?’이다. 먼저 첫 번째 질문에 대한 규명을 위해 지방공공서비스의 공급방식 간의 효율성에 관한 이론적 검토와 선행연구를 통해 지방공공서비스를 공공성과 성과측정 용이성의 두 가지 특성 기준에 따라 4가지 유형으로 분류하였다. <유형 Ⅰ>은 공공성이 높고 성과측정이 어려운 공공서비스로 상수도 서비스와 도서관 운영을 선정하였으며, 공공성은 높으나 성과측정이 용이한 <유형 Ⅱ>에 해당하는 서비스는 하수처리 서비스와 생활폐기물 처리 서비스를 선정하였다. <유형 Ⅲ>은 공공성은 낮으나 성과측정이 어려운 공공서비스로 문예회관 운영과 청소년수련관 운영을 선정하였다. 마지막으로 공공성과 성과측정의 난이도가 모두 낮은 <유형 Ⅳ>의 서비스로 공영주차장 운영과 자연휴양림 서비스를 선정하였다. 지방공공서비스 별 효율성 분석과 공급방법별 효율성 비교를 위해서 공공부문의 효율성 분석에 유용한 투입모형 자료포락분석(DEA : data envelopment analysis)을 사용하였다. 다음 2단계에서는 1단계 분석에서 산출된 효율성 값을 종속변수로 하여 효율성에 영향을 미치는 요인을 검증하였다. 영향요인을 검증하기 위해 독립변수로는 재정적 특성, 정치적 특성, 지역적 특성을 고려하여 13개의 구체적인 변수들을 가지고 가설을 설정하고 패널-토빗 회귀(Panel-Tobit Regressioner)분석을 하였다. 각 특성별 구체적인 변수들은 재정적 특성 변수로는 1인당 지방세액, 1인당 재산세액, 재정자립도, 부채비율을 사용하였으며 정치적 특성 변수로는 지방자치단체장의 선수, 지역단위 정권교체 여부, 자치단체장 선거 득표율, 지방선거 투표율, 지방자치단체장 소속 정당과 의회 다수당 일치 여부를 사용하였다. 끝으로 지역적 특성에서는 인구 규모, 인구밀도, 면적, 도시화율을 사용하였다. 이 연구는 전국 기초 지방자치단체 227개를 대상으로 하였으며 시간적 범위는 2009년부터 2018년까지 10년간이다. 다만 지방 공공서비스에 따라서는 관련 통계자료 확보가 어려워 자연휴양림은 2010년부터 2018년까지 9년, 공영주차장과 청소년수련관은 2014년부터 2018년까지 5년을 대상으로 하였다. 이 연구의 분석 결과를 요약하면 다음과 같다. 먼저 우리나라 지방공공서비스의 효율성은 매우 낮은 수준으로 나타났다. 8개 공공서비스의 효율성 평균은 기술효율성(CRS) 0.51, 운영효율성(VRS) 0.64, 규모효율성(SE) 0.80으로 비효율성이 각 49%, 36%, 20%정도로 나타나 효율성 향상을 위한 노력이 필요함을 알 수 있다. 개별 공공서비스별로는 기술효율성(CRS)을 기준으로 볼 때 생활폐기물 처리 서비스가 효율성 값 0.76으로 다른 서비스에 비해 가장 효율적으로 운영되고 있으며, 자연휴양림 운영 0.58, 공영주차장 운영 0.57, 상수도 서비스 0.56 순으로 효율성이 높다. 도서관 운영, 하수처리, 문예회관 운영, 청소년수련관 운영은 0.44 수준의 낮은 효율성을 보여 효율성 향상을 위한 대책이 시급함을 알 수 있다. 비효율성의 원인으로는 운영의 비효율성이 규모의 비효율성보다 높아 순수 기술효율성인 운영상의 비효율이 공공서비스 비효율의 주된 원인으로 나타났다. 따라서 최신 생산기술 및 설비의 도입, 업무 공정의 재설계, 담당 인력의 전문성 확보를 비롯한 인력과 조직 운영의 효율성 강화, 재정투입의 적절성 제고 등이 효율성 향상을 위해 필요하다. 규모효율성의 측면에서는 대부분의 지방자치단체나 공공서비스 DMU가 규모수익체증(IRS) 구간에서 생산을 하는 과소규모로 운영되는 것이 비효율성의 원인으로 분석되었다. 지방공공서비스의 유형에 따른 공급방식별 효율성과 관련하여 평균효율성과 효율성 값이 1인 공급방식의 개수와 비율을 기준으로 분석한 결과, 직영방식은 상수도 서비스, 문예회관 운영, 청소년문화원 서비스에서 효율성이 높은 결과를 보여주었다. 공공위탁은 하수처리 서비스와 생활폐기물 처리 서비스에서 효율성이 높았다. 민간위탁 방식은 공공도서관 운영, 공영주차장 운영, 자연휴양림 운영에서는 효율성을 보였으나, 민간위탁 방식으로 서비스가 많이 이루어지는 하수도 서비스, 생활폐기물 처리, 청소년수련관 운영 운영에서는 효율성을 보이지 못했다. 서비스 유형별로 효율성이 높은 공급방식을 살펴보면 공공성이 높고 성과측정도 상대적으로 어려운 공공서비스인 <유형 Ⅰ>의 상수도와 공공도서관 서비스에서는 상수도의 경우는 직영이 우수하였으나 공공도서관은 민간위탁 방식이 우수한 결과를 보였다. <유형 Ⅱ>인 공공성이 높고 성과측정이 비교적 쉬운 하수처리 서비스와 생활폐기물 수거 서비스에서는 공공위탁이 가장 우수한 결과를 보였다. 공공성은 낮으나 성과측정이 어려운 서비스로 분류되는 <유형 Ⅲ>의 서비스에서는 문예회관 운영과 청소년수련관 운영 모두 직영방식이 상대적으로 우수한 효율성을 보였다. 공공성도 낮으며 성과측정도 용이한 <유형 Ⅳ>의 서비스인 공영주차장 운영과 자연휴양림 서비스에서는 모두 민간위탁 방식이 효율적인 결과를 보였다. 영향요인에 대한 패널-토빗 회귀분석(Panel-Tobit Regression Aanalysis)을 한 결과, 재정적 변수, 정치적 변수, 지역적 변수가 모두 지방 공공서비스의 효율성에 영향요인으로 유의하게 작용하고 있는 것을 발견했다. 재정변수는 공영주차장을 제외한 모든 공공서비스의 효율성에 유의한 영향을 미치는 것으로 검정되었다. 1인당 지방세는 상수도의 기술효율성, 생활폐기물의 운영효율성에는 정의 유의성을 보여 가설을 인용하였으나 문예회관, 도서관, 자연휴양림 운영에서는 부의 유의성을 가져 가설과 반대의 결과를 보였다. 재정자립도는 자연휴양림 운영에서는 부의 유의성을 보였지만 상수도, 도서관 운영, 생활폐기물 처리, 문예회관과 청소년수련관 운영에서는 정의 유의성을 보여 가설을 인용하였다. 1인당 재산세는 하수도, 생활폐기물 처리에서는 정의 유의성을 보였으나 자연휴양림 운영에서는 부의 유의성을 보였다. 부채비율은 상수도 운영에서만 부의 유의한 관계를 보여 효율성에 미치는 영향이 크지는 않은 것으로 분석되었다. 재정변수 중에는 재정자립도가 가장 많은 공공서비스에 유의한 영향을 미치고 가설을 인용하였다. 정치적 영향요인은 생활폐기물 처리와 공영주차장을 제외한 공공서비스의 효율성에 유의한 영향을 미치는 것으로 검정되었다. 지방자치단체장의 득표율은 상수도 운영에서는 정의 유의성을 보였으나 문예회관 운영과 하수도 서비스에서는 부의 유의성으로 가설을 기각하였다. 지방선거 투표율은 상수도에서만 유의했으나 가설은 기각되었다, 지방자치단체장과 의회 다수당의 일치 여부는 문예회관과 하수도 서비스에서 유의하였으나 문예회관에서는 정의 유의성을 하수도에서는 부의 유의성을 보였다. 지역단위 정권교체는 상수도와 도서관 운영에서 정의 유의성으로 가설에 부합하였고 지방자치단체장의 선수는 하수도 서비스에서 정의 유의성, 자연휴양림 운영에서 부의 유의성을 보여 반대의 작용을 하였다. 지역적 영향요인은 분석대상이 되는 모든 공공서비스의 효율성에 유의한 영향을 미치는 것으로 검정 되었다. 면적은 상수도 서비스, 하수도 서비스, 공영주차장 그리고 자연휴양림 운영에서 부의 유의성을 가졌으며 생활폐기물 처리에서만 정의 유의성을 가졌다. 인구규모는 도서관, 문예회관, 생활폐기물 처리, 청소년수련관 운영의 기술효율성에는 정의 유의성을 보였으나, 하수도와 생활폐기물 운영효율성에서는 유의한 부의 관계를 보였다. 인구밀도는 좁은 면적에 많은 인구가 거주하고 있어 서비스의 공급과 수요에서 효율성을 높이는 기제로 당연히 작용할 것으로 기대했으나 확실한 정의 관계를 보인 것은 도서관과 청소년수련관 운영 서비스에 불과했다. 이번 연구를 통해 나타난 정책적 시사점은 우리나라 지방자치단체의 공공서비스의 효율성이 매우 낮아 서비스 효율성 향상을 위한 개선방안의 마련이 시급하다는 것이다. 먼저 공급방법과 관련하여 신공공관리론에서 주장하는 바와 같은 민간위탁의 효율성을 전제로 한 민간위탁 방식의 도입은 재고되어야 한다. 공공성이 높고 성과측정이 어려운 공공서비스에서 직영 방식의 효율성이 높은 결과와 공공성이 높고 성과측정이 용이한 서비스에서 공공위탁의 효율성이 높은 결과를 보인 것을 고려하여, 공공서비스의 특성과 시장의 경쟁성 확보 등 조건을 고려하여 공급방식이 결정되어야 한다. 또한, 우리나라 지방공공서비스의 민간위탁 방식 운영에 대한 개선이 필요하다는 것이다. 민간위탁의 성공을 위해서는 시장에서의 경쟁성 확보, 체계적인 관리 감독과 평가를 통한 재계약의 결정 등으로 수탁자의 도덕적 해이를 방지해야 한다. 그러나 우리나라 민간위탁은 관리적인 측면에서 문제가 많은 것이 드러나 이에 대한 개선이 필요하다. 두 번째는 지방자치단체 공공서비스의 공급방식인 기존의 직영, 공공위탁, 민간위탁 방식을 벗어나 지방자치단체간 위탁 또는 공동생산 등 새로운 방식의 도입이 필요하다는 것이다. 이번 연구에서 상수도를 제외하면 분석대상인 공공서비스가 모두 규모수익체증(IRS)구간에서 공급이 이루어지고 있어 생산규모를 확대하면 규모의 효율성이 높아져 전반적인 효율성인 기술효율성이 높아질 수 있다. 이를 위해 인근 지방자치단체간 공공서비스의 위탁 운영이나 공동생산 방식의 도입이 필요하다. 특히, 도서관, 문화예술관, 청소년수련관처럼 가치재로서 효율성이 잠재적 수요자인 인구 규모의 영향을 많이 받는 경우 인구 규모를 고려하지 않고 지방자치단체별로 설치하여 공급할 것이 아니라 자치단체 간 업무위탁을 통해 통합 운영하는 방안 등도 새로운 공급방식으로 고려해야 한다. 또한 상수도와 하수도의 경우와 같이 면적이 서비스 비용에 중요한 요인이 되고 생산설비 역시 규모의 효율성을 높여야 전체적인 효율성을 높일 수 있는 서비스의 경우에는 지방자치단체의 획일적인 경계구역을 기준으로 한 서비스 구역을 정할 것이 아니라 경계를 신축적으로 적용하여 생산설비와 공급망 모두 고려했을 때 최적의 규모 효율성을 달성할 수 있도록 해야 한다. 세 번째 시사점은 지방자치단체의 지방재정 운영의 자율성과 책임성의 향상과 더불어 지방선거 등 지방정치가 공공서비스의 효율성 향상에 도움이 되도록 개선하는 것이 필요하다. 이번 연구 결과에 따르면 우리나라 지방재정 운영과 지방선거가 지방 공공서비스 효율성을 높이도록 작용하기가 어렵다. 조례에 의한 세목의 신설, 세율의 조정 등 지방자치단체에게 지방세에 관한 더 많은 자율성이 부여되어야 하며 국가와 지방간 세원 배분을 통해 재정확충도 이루어져야 한다. 지방교부세도 실질적인 지방재원으로서 지방자치단체의 재정운영의 자율성과 책임성을 확보할 수 있도록 배분방식의 개선이 필요하다. 우리나라 지방정치는 전국 동시 지방선거, 지방자치단체장과 의회 의원의 공천제도를 비롯해 지방정치가 중앙정치에 예속되도록 설계되어 있다. 현재와 같은 중앙정치에 예속된 형태로 치러지는 선거의 결과는 지방자치단체의 운영효율성에 긍정적으로 작용하지 못한다. 지방자치의 기반이 되는 정치제도와 선거제도를 개선해야 한다. 이 연구가 갖는 의의는 이론적 측면에서는 지방공공서비스에 대한 새로운 유형화에 대한 시도이며 방법론적인 측면에서는 빅데이타 분석이다. 기존 연구에서 공공서비스 유형에 대한 새로운 시도와 8개의 공공서비스에 대해 10년간의 빅데이타를 분석한 예는 찾아보기 힘들다. 또한 이러한 빅데이타 분석의 결과 공공서비스의 특성에 따른 공급방식의 효율성에 차이에 관한 기존의 이론이나 주장을 입증하였다. 공공성이 높은 서비스인 상수도 운영, 하수처리, 생활폐기물 처리는 직영의 효율성이 높아 공공성이 높은 서비스는 직접 공급하여 서비스 실패에 따른 책임과 비난을 최소화하려고 한다는 Levin & Tadelis(2010)의 연구와 일치한다. 또한 성과측정이 어려운 공공서비스인 문예회관 운영, 청소년수련관 서비스는 모두 직영으로 운영하는 것이 효율적이어서 성과측정이 어려운 서비스는 민간위탁의 효율성이 떨어진다는 Brown & Potoski(2003)의 연구와 일치한다. 또한 민간위탁을 하는 경우 위탁업체의 선정과정에서 실질적 경쟁이 이루어지지 않아 효율성이 떨어진다는 결과는 민간위탁이 성공하기 위해서는 시장에서의 경쟁력 확보가 필요하다는 Hefetz & Warner(2004) 등의 주장을 입증한다.

An experimental study on the development and verification of three-dimensional tractive force measuring device using loT-based arduino

이재경 인제대학교 일반대학원 2019 국내석사

When the flow in a stream goes any further, it starts to sweep small sand particles of the material form the river bed or the bank, and tractive force is defined as the ability to make sand particles to move, i.e. the shear stress acting on the bottom boundary. Evaluation of tractive force is essential for prevention of damage or erosion on river bed and embankment during a flood and efficient maintenance of rivers. Because it is difficult to directly and accurately measure for the tractive force, in the U.S. and Japan, the tractive force is estimated and used through the hydraulic experiment on revetment technique. In Korea, research has been conducted to directly measure tractive force recently, including the development of a device to measure one-dimensional tractive force using shear plates. Because information and communication technologies such as Internet of Things (IoT) and Big Data due to 4th Industrial Revolution have become more accessible to individuals due to convergence with daily life, it is possible to improve measurement convenience at the low price of tractive force measurement devices using a data logger developed with this technology. The purpose of this study is to develop a device to integrate IoT technology into the developed tractive force system using arduino, which is capable of monitoring data using the internet and smart phone. The limitation of the measuring device using the arduino is that the transmission delay is caused by the WiFi module during the data transmission for monitoring. In order to compensate for these limitations while maintaining the usefulness of the measuring device, a method has been developed in this study to transmit a 3 minute mean value using a data averaging technique. For the verification of the developed arduino measuring device, 3-dimensional tractive force measurement device using arduino and 3-dimensional tractive force measurement device using a data logger were compared. In addition, by analyzing the hydraulic characteristic of the high speed channel, the tractive force calculated using the theoretical equation (Reach-Averaged method, TKE method, Reynolds stress method), and the measurement value of tractive force using the arduino and the measurement value of tractive force using a data logger were compared. The results of the experiment showed that the measured data using the arduino has more data deviation than the measured data using the data logger and it was confirmed that the measured data using the arduino is somewhat lower in terms of precision. The tractive force measured by the tractive force system was similar to the tractive force of the Reach-Averaged method calculated using 0.012 of the roughness coefficient of acrylic. The numerical value of tractive force TKE and Reynolds stress method was very different. In order to use TKE and Reynolds stress method that analyzes the tractive force due to turbulence characteristic, the turbulent velocity field must be measured, but it is judged that the main reason is that sufficient velocity data cannot be obtained under the high velocity conditions. Considering the limitation of measurement of various hydraulic characteristic value such as the turbulent velocity in the high velocity, it is considered that the device for measuring the direct tractive force using arduino is very useful.

비접촉식 3차원 측정기의 곡면 추적장치에 관한 연구

김병기 한양대학교 산업대학원 1992 국내석사

A positioning system with long-range high-precision displacement sensor integrated for measuring molecular bonding forces

김성주 포항공과대학교 일반대학원 2012 국내박사

The working area of ultra-precision position-control devices has been expanding to meet the demands of a wide range of scientific and industrial applications. To achieve the requirement for a high-dynamic-range position-control system with reduced size and complexity, a contact-type linear encoder-like capacitive displacement sensor (CLECDiS) was developed to measure displacements over the millimeter range with nanometer resolution. However, small changes in the contact conditions due to the surface profile or friction, which are inherent characteristics of contact sensors, lead to significant distortion of the output signal. Thus, reliable contact conditions during CLECDiS measurement must be achieved to enable practical application of the device. In this thesis, in order to design an instrument with reliable contact conditions, the contact conditions were analyzed by characterizing the signal distortion, observing the pressure distribution between the contacting surfaces, and measuring the motional errors of the sensor using a laser Doppler vibrometer (LDV). A mechanism based on the analyses is proposed and a manufactured prototype instrument enabled the CLECDiS to measure displacement with improved reliability. The prototype was integrated into a dual-actuated stage to develop an ultra-precision long-travel-range position-control system. A null motion control strategy was used for this redundant system, and a fringe subdivision technique using quadrature phase signals from the CLECDiS was applied to convert the capacitance variable signal to a displacement. As a result, the developed positioning system based on the CLECDiS achieved an accuracy and repeatability of hundreds of nanometers over several millimeters of working area; it also showed the ability to provide nanometer-scale position control if the read-out or pattern design of the CLECDiS is enhanced. In addition, a new method that requires an ultra-precision long-range position-control system is proposed to increase the reliability of bio-molecular bonding force measurements using scanning probe microscopy (SPM) and a micro-machined nanodot. When using the probing method to measure the unbinding molecular interaction forces, unlike conventional techniques, the substrate is treated so that a single molecule is likely to attach to the nanodot. Then, the unbinding forces can be measured by drawing force–distance (F–D) curves while probing around the nanodot. The unbinding force between a single protein (vibrio cholera toxin B subunit) and a carbohydrate (GM1 pentasaccharide) was successfully measured around a nanodot, demonstrating the potential of the developed technique and instrument to increase the reliability of molecular bonding force measurements. However, in this application, a dual-stage made of commercially available coarse and fine stages was applied to a laboratory-made SPM because the developed position-control system using CLECDiS has not yet achieved the required nanometer-scale accuracy and repeatability.

표면적 변화에 따른 직물 호흡 센서의 디자인 방향

이승표 연세대학교 대학원 2017 국내석사

In this study, a textile respiration sensor (TRS) that can be applied to clothing is proposed. I investigated (part I) the possibility of measuring TRS as a dummy object. Additional research (part II) was conducted to investigate the characteristics of TRS in seven adult men. Research studies I and II set the variables of the study as the three types of TRS, speed of respiration, and measurement position of TRS (applied only in part II). In order to observe the TRS respiration accuracy, reproducibility, and reliability, BIOPAC, a typical wearable respiration sensor in the field of medical devices, was used at a position adjacent to the TRS, and the respiration rate was simultaneously measured through the two sensors. The measured results obtained were compared and analyzed. The values of respiration rate and continuous voltage changes in the respiration rate were measured. The respiration rate was calculated by determining the percentage of arithmetic mean standard deviation, and the continuous voltage variation resulted in the calculation of the Pearson correlation coefficients and validation. In part I of the research study, we investigated the possibility of using the TRS as a respiration rate sensor in terms of accuracy, reproducibility, and reliability using a dummy. An analysis of the agreement between TRS and BIOPAC showed that the Type-3 sensor has a relatively high accuracy. In addition, an analysis of the TRS sensing results and actual respiration rate showed that the Type-1 sensor has relatively high accuracy. By comparing the reproducibility of TRS with BIOPAC, it was observed that BIOPAC had an overall higher reproducibility than TRS. By comparing the reproducibility according to type of TRS, the Type-2 sensor for slow respiration and the Type-1 sensor for normal respiration and fast respiration were observed to maintain relatively high reproducibility. Results of the TRS reliability analysis indicated that all TRS types showed high reliability over 0.900 ** (**. P <.01) at slow respiration, and that the Type-2 sensor showed a reliability higher than 0.900 ** (**. P <.01) at all speeds of respiration. In part II of the research study, we investigated the possibility of using a TRS as a respiration rate sensor in terms of accuracy, reproducibility, and reliability for humans. An analysis of TRS and BIOPAC showed that Type-1 sensor has a relatively high accuracy. In addition, an analysis of TRS sensing results and actual respiration rates showed that Type-2 sensor has relatively high accuracy. A comparison of reproducibility between TRS and BIOPAC indicated that for high reproducibility, all three types of sensors were located at the center of the chest. By comparing the reproducibility according to the type of TRS, it was observed that Type-1 sensor was located at the side of the upper abdomen, Type-2 sensor was located at the center of the upper abdomen, and Type-3 sensor maintained relatively high reproducibility at the center of the chest. Through TRS reliability analysis, it was observed that Type-1 sensor and the side position of the upper abdomen maintained their reliability at all speeds of respiration. In addition, the reliability of normal respiration and fast respiration was maintained using Type-2 sensor and the center of the chest, Type-2 sensor and the middle position of the upper abdomen, Type-2 sensor and the upper side position, Type-3 sensor and the middle position of the upper abdomen, and Type-3 sensor and the upper side of the upper abdomen. Based on the results of this study, the combination of speed of respiration, TRS type, and measurement position suitable for clothing was derived, and the design direction of the clothing was determined accordingly. 본 연구는 의복에 적용 가능한 입체적 구조의 직물 호흡 센서(이하 TRS로 약칭, Textile Respiration Sensor)를 제안하고, 더미 대상으로 TRS의 측정 가능성을 탐색하기 위한 연구Ⅰ과 7명의 20대 남성을 대상으로 TRS의 특성을 고찰하기 위한 연구Ⅱ를 수행하였으며, 그 결과를 토대로 TRS의 의복 적용 디자인 방향을 제시하였다. 연구Ⅰ, Ⅱ를 수행하기 위해 설정한 연구의 변인은 TRS의 세 가지 유형, 호흡 속도, TRS의 측정 위치(연구Ⅱ에서만 적용) 등이었다. TRS의 호흡수 센싱 정확도, 재현성, 신뢰도를 관찰하기 위해 의료기기 분야의 대표적 착용형 호흡수 센서인 BIOPAC을 TRS의 인접 위치에 함께 착용시켜 두 센서를 통해 호흡수를 동시에 측정한 후, 두 센서로부터 획득되는 측정 결과를 비교분석 하였다. 측정된 값은 호흡수와 호흡수 센싱 시의 연속적인 전압변화량이었다. 이 중 호흡수 측정 결과에 대해서는 산술평균 표준편차 백분율 등을 산출하여 분석하였으며, 연속된 전압변화량에 대해서는 Pearson 상관계수 산출 및 유의성 검증을 실시하였다. 연구Ⅰ에서는 더미를 대상으로 하여 TRS의 호흡수 센서로서의 가능성을 정확도, 재현성, 신뢰도 측면에서 탐색하였다. TRS와 BIOPAC과의 일치도를 분석한 결과 Type 3 센서가 높은 정확도를 지니는 것으로 관찰되었다. 또한 TRS의 센싱 결과와 실제 호흡수와의 일치도를 분석한 결과 Type 1 센서가 높은 정확도를 지니는 것으로 관찰되었다. TRS와 BIOPAC의 재현성을 비교한 결과 BIOPAC이 TRS보다 전반적으로 높은 재현성을 지니는 것으로 관찰되었다. TRS의 유형에 따른 재현성을 비교한 결과 느린 호흡 시에는 Type 2 센서, 보통 호흡과 빠른 호흡 시에는 Type 1 센서가 높은 재현성을 유지하는 것으로 관찰되었다. TRS의 신뢰도를 분석한 결과 느린 호흡 시에는 모든 TRS 유형이 0.900** (**. p < .01) 이상의 높은 신뢰도를 나타내었으며, Type 2 센서가 모든 호흡 속도에서 0.900** (**. p < .01) 이상의 높은 신뢰도를 나타내었다. 연구Ⅱ에서는 인간을 대상으로 하여 TRS의 요건에 따른 호흡수 센싱의 정확도, 재현성, 신뢰도를 고찰하였다. TRS와 BIOPAC과의 호흡수 센싱 일치도를 분석한 결과 Type 1 센서가 높은 정확도를 지니는 것으로 관찰되었다. 또한 TRS의 센싱 결과와 실제 호흡수와의 일치도를 분석한 결과 Type 2 센서가 높은 정확도를 지니는 것으로 관찰되었다. TRS와 BIOPAC의 재현성을 비교한 결과 모든 TRS 유형은 가슴 중앙 위치에서 높은 재현성을 지니는 것으로 관찰되었다. TRS의 유형에 따른 재현성을 비교한 결과 Type 1 센서는 상복부 측면 위치, Type 2 센서는 상복부 중앙 위치, Type 3 센서는 가슴 중앙 위치에서 높은 재현성을 유지하는 것으로 관찰되었다. TRS의 신뢰도를 분석한 결과 모든 호흡 속도에서 신뢰도가 유지하는 경우는 Type 1 센서와 상복부 측면 위치인 것으로 관찰되었다. 또한 보통 호흡과 빠른 호흡에서 신뢰도가 유지되는 경우는 Type 2 센서와 가슴 중앙 위치, Type 2 센서와 상복부 중앙 위치, Type 2 센서와 상복부 측면 위치, Type 3 센서와 상복부 중앙 위치, Type 3 센서와 상복부 측면 위치가 조합된 경우들인 것으로 관찰되었다. 이상의 연구 결과를 토대로 의복에 적용하기에 적합한 호흡속도, TRS 유형, 측정 위치간의 조합을 도출하고, 이에 따른 의복 적용 디자인 방향을 제시하였다.