Review of Soil Structure Quantification from Soil Images

전현정,Daniel Gimenez,윤성원,박찬원,문용희,손연규,현병근 한국토양비료학회 2011 한국토양비료학회지 Vol.44 No.3

Soil structure plays an important role in ecological system, since it controls transport and storage of air, gas,nutrients and solutions. The study of soil structure requires an understanding of the interrelations and interactions between the diverse soil components at various levels of organization. Investigations of the spatial distribution of pore/particle arrangements and the geometry of soil pore space can provide important information regarding ecological or crop system. Because of conveniences in image analyses and accuracy,these investigations have been thrived for a long time. Image analyses from soil sections through impregnated blocks of undisturbed soil (2 dimensional image analyses) or from 3 dimensional scanned soils by computer tomography allow quantitative assessment of the pore space. Image analysis techniques can be used to classify pore types and quantify pore structure without inaccurate or hard labor in laboratory. In this paper, the last 50years of the soil image analyses have been presented and measurements on various soil scales were introduced,as well. In addition to history of image analyses, a couple of examples for soil image analyses were displayed. The discussion was made on the applications of image analyses and techniques to quantify pore/soil structure.

전통목구조해석의 문제점 분석과 개선방안

정성진(Jung, Sung-Jin) 대한건축학회 2017 大韓建築學會論文集 : 構造系 Vol.33 No.10

In structure design practical fields, computer programs like MIDAS and SAP2000 etc. are widely used for the evaluation of the structural performance of the Korean traditional wood structures. It is necessary to use a reasonable analysis model and method for the evaluation of the structural performance. Considering the structural characteristics of the Korean traditional wood structures, it is appropriate to analyze lower frame composed of beam-columns and upper frame which is a roof structure separately. Especially, in the analysis including lateral loads like seismic or wind load etc., it seems to be reasonable to analyze lower frame with an assumption of roof frame as a rigid diaphragm. Because connections between columns and beams have very small rotational stiffness, lower frame may be unstable. So, in the structure design practical fields, connections are modelled by using various assumptions and linear analysis is performed mainly. However, irrationality may be included in these assumptions and analysis method unfortunately. Therefore, in this study, problems in the analysis models and methods for the Korean traditional wood structures, used in structure design practical fields, are investigated first, then some improvement plans are proposed on the basis of investigation results. Because the Korean traditional wood structures may have no high lever stabilities, it is necessary to perform geometric nonlinear analysis. So, geometric nonlinear analysis method including P-δ effect is studied.

Numerical analysis for the structural strength comparison of St. Jude Medical and Edwards MIRA bileaflet mechanical heart valve prostheses

권영주 대한기계학회 2010 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.24 No.2

This paper presents a numerical analysis for the structural strength comparison of the St. Jude Medical bileaflet mechanical heart valve prosthesis with flat leaflet and the Edwards MIRA bileaflet mechanical heart valve prosthesis with curved leaflet. Computer aided engineering systems are used in the analysis. The blood fluid pressure is applied to both flat and curved leaflets of the bileaflet mechanical heart valve prostheses for the rigid body dynamic analysis to confirm the almost same dynamic characteristics of both flat and curved leaflet motions. Thereafter, using the same blood fluid pressure and dynamic characteristics of leaflet motions, structural mechanic analyses for both flat and curved leaflets of the mechanical heart valve prostheses are carried out to show quite different stress and deformation results, respectively. Conclusively, from the viewpoint of stress, it is revealed that the St. Jude Medical bileaflet mechanical heart valve prosthesis is structurally stronger and better than the Edwards MIRA bileaflet mechanical heart valve prosthesis. Computer aided engineering systems used in this comparative structural analysis are ADAMS for the rigid body dynamic analysis, and NISA for the structural mechanic analysis.

A Study on Error Types Represented in Computer-Based Speaking and Computer-Based Writing: Centered around Korean Learners

( Gereltuya Munkh Ochir ),( Chang In Lee ) 한국멀티미디어언어교육학회 2015 멀티미디어 언어교육 Vol.18 No.3

This study aims to identify the most frequently erroneous linguistic and surface structure forms committed in computer-based speaking (CBS) and computer-based writing (CBW) performances by Korean university students. To examine the errors, a total number of thirty students were involved in two different tasks (CBS and CBW) based on the same question “Do you prefer living off campus or on campus? Use specific reasons and details to support your answer” on a certain given time. Their CBS and CBW samples were collected and analyzed based on the two main error analysis taxonomies: linguistic and surface structure. The linguistic taxonomy included the syntactic complexity (number of sentences, embedded sentences, tokens, and types) and word level errors(-ed/-ing, singular, plural forms, and subject-verb agreement), whereas the surface structure taxonomy focused on deletion, addition, repetition, substitution, ordering, and run-on sentences. The participants’ CBS and CBW samples have been implemented as research instruments while manipulating the descriptive statistics and t-test analysis purposes. According to the overall analysis, the students committed the following errors. First, the results of the linguistic error analysis focusing on the syntactic complexity revealed that they produced more tokens and types in CBW than in CBS and also yielded more sentences and embedded sentences in CBW than in CBS. Likewise, the analysis under the word level errors was carried out and identified that the most prominent errors in terms of the morphemes (-ing/-ed) and subject-verb agreement committed in CBS than in CBW. However, fewer errors in singular and plural forms in CBS were found than in CBW. Second, the results under the category (Surface Structure Error Taxonomy) were carefully examined and identified the following findings. More addition errors were identified in CBS than in CBW. However, the errors on deletion, repetition, and substitution in CBS and CBW showed no significant differences statistically.

가스소화약제 압력누기감시장치의 안전성 분석을 위한 수치적 연구

고아라,임동오,손봉세 한국화재소방학회 2016 한국화재소방학회논문지 Vol.30 No.4

While the demand for the gas system fire extinguishers increases every year, there are insufficient safety measures forassessing the extinguishing performance, such as system safety and reliability in the preparation of increasing demand,which has emerged as a social problem. One of the most critical causes of accidents occurring with the gas extinguishingsystem is pressure leakage from the extinguishing agent storage container. This is considered to be one of the critical factorson which the success of fire suppression depends. In this study, its safety measure was studied, Because it wasdeemed urgently necessary. The newly developed pressure leakage monitoring system is a system monitoring storage condition,pressure, leakage and discharge of the storage container related to agent concentration, which is one of the criticalfactors for fire suppression. This was developed to be applicable to the CO2 and HFC-23 systems. Therefore, for structuralsafety analysis, the safety performance was verified by the fluid structure coupling analysis of the safety problemsthat may occur when the pressure leakage monitoring system is applied to the gas fire extinguisher. For analysis programs,the FloEFD program from Mentor Graphics was used for computational fluid dynamics analysis and ABAQUSfrom Dassault Systems was used for structural analysis. From the result of numerical analysis, the structure of CO2 did notdevelop plastic deformation and its safety was verified. However, plastic deformation and deviation issue occurred withthe HFC-23 monitoring system and therefore verified the structural safety of pressure leakage monitoring system by dataobtained from redesigning and adjusting the condition of numerical interpretation three times. 가스계소화설비의 수요는 매해 증가하고 있으나, 늘어나는 수요에 대비한 시스템의 안전성 및 신뢰성등 소화성능에 필요한 안전대책이 미흡하여 사회적인 문제가 되고 있는 실정이다. 본 연구에서는 이러한 문제점을 해결하기 위하여 가스소화시스템의 사고발생 원인 중에서 가장 심각한 문제인 소화약제 저장용기에서 발생하는 압력누기는 화재진압의 성패를 좌우하는 중요한 요소로 시급한 대책이 요구되는 문제점로 판단하여 연구를 하였다. 새로 개발한 압력누기감시장치는화재진압에 중요한 요소인 소화농도와 관련이 있는 저장용기의 약제확보상태와 압력 및 누기, 방출상태 등을 감시하는장치로 CO2와 HFC-23 시스템에 적용할 수 있도록 개발하였다. 즉, 압력누기감시장치를 가스소화설비에 적용하였을 때발생할 수 있는 구조적 안전성 분석을 위하여 유체-구조연계해석을 통하여 안전성능을 검증하였다. 해석에 사용한 프로그램으로 전산유체해석은 Mentor Graphics사의 FloEFD 프로그램을 사용하였고, 구조해석 프로그램은 Dassault systems사의 ABAQUS를 사용하였다. 수치해석결과 CO2용의 구조에서는 소성변형이 발생하지 않아 안전성을 확인하였으나HFC-23용 감시장치에는 소성변형 및 이탈문제가 발생하여 설계수정과 3차례의 수치해석 조건을 수정하여 얻은 데이터를 기본으로 압력누기감시장치의 구조적인 안전성을 확인하였다.

Fluid-structure interaction analysis of deformation of sail of 30-foot yacht

박세라,유재훈,송창용 대한조선학회 2013 International Journal of Naval Architecture and Oc Vol.5 No.2

Most yacht sails are made of thin fabric, and they have a cambered shape to generate lift force; however,their shape can be easily deformed by wind pressure. Deformation of the sail shape changes the flow characteristics over the sail, which in turn further deforms the sail shape. Therefore, fluid-structure interaction (FSI) analysis is applied for the precise evaluation or optimization of the sail design. In this study, fluid flow analyses are performed for the main sail of a 30-foot yacht, and the results are applied to loading conditions for structural analyses. By applying the supporting forces from the rig, such as the mast and boom-end outhaul, as boundary conditions for structural analysis,the deformed sail shape is identified. Both the flow analyses and the structural analyses are iteratively carried out for the deformed sail shape. A comparison of the flow characteristics and surface pressures over the deformed sail shape with those over the initial shape shows that a considerable difference exists between the two and that FSI analysis is suitable for application to sail design.

Fluid-structure interaction analysis of deformation of sail of 30-foot yacht

Bak, Sera,Yoo, Jaehoon,Song, Chang Yong The Society of Naval Architects of Korea 2013 International Journal of Naval Architecture and Oc Vol.5 No.2

Most yacht sails are made of thin fabric, and they have a cambered shape to generate lift force; however, their shape can be easily deformed by wind pressure. Deformation of the sail shape changes the flow characteristics over the sail, which in turn further deforms the sail shape. Therefore, fluid-structure interaction (FSI) analysis is applied for the precise evaluation or optimization of the sail design. In this study, fluid flow analyses are performed for the main sail of a 30-foot yacht, and the results are applied to loading conditions for structural analyses. By applying the supporting forces from the rig, such as the mast and boom-end outhaul, as boundary conditions for structural analysis, the deformed sail shape is identified. Both the flow analyses and the structural analyses are iteratively carried out for the deformed sail shape. A comparison of the flow characteristics and surface pressures over the deformed sail shape with those over the initial shape shows that a considerable difference exists between the two and that FSI analysis is suitable for application to sail design.

Affective Computing 분야의 지식생산, 지식구조와 네트워킹에 관한 분석 연구

오지선 ( Jee-sun Oh ),백단비 ( Dan-bee Back ),이덕희 ( Duk-hee Lee ) 한국감성과학회 2020 감성과학 Vol.23 No.4

Social problems, such as economic instability, aging population, heightened competition, and changes in personal values, might become more serious in the near future. Affective computing has received much attention in the scholarly community as a possible solution to potential social problems. Accordingly, we examined domestic and global knowledge structure, major keywords, current research status, international research collaboration, and network for each major keyword, focusing on keywords related to affective computing. We searched for articles on a specialized academic database (Scopus) using major keywords and carried out bibliometric and network analyses. We found that China and the United States (U.S.) have been active in producing knowledge on affective computing, whereas South Korea lags well behind at around 10%. Major keywords surrounding affective computing include computing, processing, affective analysis, research, user modeling categorizing recognitions, and psychological analysis. In terms of international research collaboration structure, China and the U.S. form the largest cluster, whereas other countries like the United Kingdom, Germany, Switzerland, Spain, and Canada have been strong collaborators as well. Contrastingly, South Korea's research has not been diverse and has not been very successful in producing research outcomes. For the advancement of affective computing research in South Korea, the present study suggests strengthening international collaboration with major countries, including the U.S. and China and diversifying its research partners.

Review of Soil Structure Quantification from Soil Images

Chun, Hyen-Chung,Gimenez, Daniel,Yoon, Sung-Won,Park, Chan-Won,Moon, Yong-Hee,Sonn, Yeon-Kyu,Hyun, Byung-Keun Korean Society of Soil Science and Fertilizer 2011 한국토양비료학회지 Vol.44 No.3

Soil structure plays an important role in ecological system, since it controls transport and storage of air, gas, nutrients and solutions. The study of soil structure requires an understanding of the interrelations and interactions between the diverse soil components at various levels of organization. Investigations of the spatial distribution of pore/particle arrangements and the geometry of soil pore space can provide important information regarding ecological or crop system. Because of conveniences in image analyses and accuracy, these investigations have been thrived for a long time. Image analyses from soil sections through impregnated blocks of undisturbed soil (2 dimensional image analyses) or from 3 dimensional scanned soils by computer tomography allow quantitative assessment of the pore space. Image analysis techniques can be used to classify pore types and quantify pore structure without inaccurate or hard labor in laboratory. In this paper, the last 50 years of the soil image analyses have been presented and measurements on various soil scales were introduced, as well. In addition to history of image analyses, a couple of examples for soil image analyses were displayed. The discussion was made on the applications of image analyses and techniques to quantify pore/soil structure.

지점침하 하중을 구현하기 위한 컴퓨터프로그램의 알고리즘

정성진(Jung Sung-Jin),이재승(Lee Jae-Sung) 대한건축학회 2010 大韓建築學會論文集 : 構造系 Vol.26 No.1

It is necessary to consider the support settlements as loads in the structure analysis of building structures or bridge structures. Especially, in the case of a close safety investigation considering deformations or a structure analysis considering support settlements, support settlements should be considered as load conditions. Most of commercial computer programs like sap2000, midas-Gen, and so on, provide this function fortunately. However, since these computer programs only present the concept and the way of using the commands according to each programs, we can not understand the basic theories and programming methods. Also, since consideration of support settlement as load is a kind of programming technique, literatures on FEA do not deal with this subject. So, it is necessary to establish the basic theories and the programming techniques to consider support settlement in structure analysis. This study presents the concept and the programming method considering support settlement as load. Basic theories for the consideration of support settlement are studied first, where some of possible methods are investigated and presented. On the basis of these theoretical backgrounds, theoretically the most reasonable method and an available algorithm is derived, and then a computer program(sNs) is developed based on the theory and algorithm studied. Lastly, a sample analysis is performed to verify the possibility of application of sNs.