저진공 내 시료가열판과 시료의 열전달

박현재,오수기,신용현,정광화,Park, Hyon-Jae,Oh, Soo-Ghee,Shin, Yong-Hyeon,Chung, Kwang-Hwa 한국진공학회 2008 Applied Science and Convergence Technology Vol.17 No.4

진공 챔버 내부에서 열접촉된 시료가열장치와 시료 사이의 열전달 현상을 고찰하였다. 열전달은 가스 유량과 기체 압력에 따른 대류현상, 시료와 접촉하는 기판가열장치의 표면 거칠기 및 접촉압력에 따른 전도현상, 기판가열장치의 표면 방사율에 따른 복사현상으로 나누어 푸리에 식과 슈테판-볼츠만 식을 이용하여 열흐름 값을 분석하였다. 실험은 시료가열장치의 온도를 $100\;-\;500^{\circ}C$ 사이에서 일정하게 유지하면서 300 mTorr - 1 Torr 사이의 압력에 따른 시료의 온도를 측정하고, 푸리에 식과 슈테판-볼츠만 식을 이용하여 열흐름 값을 계산하였다. 열흐름 값의 산출에 사용된 푸리에 계수의 정확성을 확인하기 위해, 역으로 열흐름 값으로부터 온도차를 구하는 방법을 사용하였으며 0.33 % 오차 내에서 재현됨을 확인하였다. Heat transfer between substrate and substrate-heater in low vacuum was investigated. The convection related with gas flow and pressure, the heat conduction considering surface roughness and contact pressure, and the heat loss by radiation depending on the surface emissivity were considered. The coefficient of heat conduction $h_c$ in the Fourier's law were determined experimentally from the temperature difference between the substrate and the substrate-heater in the range of substrate-heater temperature $100\;-\;500^{\circ}C$, in the pressures of 300 mTorr - 1 Torr. The temperature difference was then calculated in the reverse way for the purpose of verification, using the heat flow and the experimentally determined coefficients. The verified temperature differences were thus obtained within 0.33 % error.

유전알고리즘을 이용한 이동로봇의 시간 및 에너지 최적제어

박현재,박진현,최영규,Park, Hyeon-jae,Park, Jin-hyun,Choi, Young-kiu 한국정보통신학회 2017 한국정보통신학회논문지 Vol.21 No.4

비선형 시스템의 이동 로봇을 원하는 목표점으로 속도, 가속도 그리고 각속도 관련 에너지를 최소한으로 사용하여 최단시간 안에 이동시키는 최적의 제어 문제를 수학적으로 푸는 것이 매우 어렵다. 본 논문에서는 유전알고리즘을 이용하여 이동 로봇의 속도, 각속도 관련 에너지를 최소화하면서 최단시간 안에 이동할 수 있는 최적제어이득을 구한다. 이동 로봇은 비선형시스템이므로 초기위치에 따라 최적제어이득이 다르게 결정된다. 따라서 초기위치 분할 점들을 설정하고 각 분할 점에서 유전알고리즘을 이용하여 최적제어이득을 구한다. 각 분할 점에서 구한 최적제어 이득으로 신경회로망을 학습시켜서 임의의 초기위치에 대한 제어이득을 구할 수 있다. 마지막으로 본 연구의 유용성을 컴퓨터 시뮬레이션 연구로 확인한다. It is very difficult to solve mathematically the optimal control problem for non - linear mobile robots to move to target points with minimum energy related to velocity, acceleration and angular velocity in minimum time. This paper proposes a method to obtain optimal control gains with which mobile robots move with minimum energy related to velocity, acceleration and angular velocity in minimum time using genetic algorithms. Mobile robots are non - linear systems so that their optimal control gains depend on initial positions. Hence initial positions are divided into some partition points and optimal control gains are obtained at each partition point with genetical algorithms. These optimal control gains are used to train neural networks that generate proper control gains at arbitrary initial position. Finally computer simulation studies have been conducted to verify the effectiveness of the method proposed in this paper.

모서리가 둥근 직육면체 중공볼을 가지는 2방향 중공슬래브의 효율적인 진동해석

박현재,김민균,이동근,박용구,김현수,Park, Hyun-Jae,Kim, Min-Gyun,Lee, Dong-Guen,Park, Yong-Koo,Kim, Hyun-Su 한국전산구조공학회 2009 한국전산구조공학회논문집 Vol.22 No.5

본 연구에서는 2방향 중공슬래브의 효율적인 진동해석을 위하여 등가의 플레이트 모델을 개발하였다. 이를 위하여 3차원 입체요소 중공슬래브 모델에 대응하는 플레이트 슬래브 모델의 등가 질량과 강성을 산출하였다. 개발된 등가 플레이트 모델의 정확성과 효율성을 검증하기 위하여 예제해석을 수행하였다. 해석결과 등가 플레이트모델의 고유진동수는 3차원 입체요소모델과 비교하여 매우 정확한 것을 확인하였다. 또한 보행하중이 가해지는 2방향 중공슬래브에 대해 등가플레이트 모델과 3차원 입체요소 모델을 사용하여 시간이력해석을 수행한 후 그 결과를 비교하였다. 해석결과 등가의 플레이트 모델이 해석시간을 상당히 줄이면서도 3차원 입체요소 모델과 거의 일치하는 결과를 나타내는 것을 확인하였다. In this study, an equivalent plate element model has been developed for an efficient vibration analysis of a biaxial hollow slab. To this end, equivalent mass and stiffness of equivalent plate element models corresponding to solid element models of example biaxial hollow slabs were calculated. To verify the efficiency and accuracy of the equivalent plate element models, structural analyses of example structures were performed. Analytical results showed that the natural frequencies of the equivalent plate element models were very close to those of the solid element models. Time history analyses of example biaxial hollow slabs subjected to walking load were conducted using the equivalent plate element models and the solid element models, and the results were compared. It could be seen based on the analytical results that the equivalent plate element model could provide very accurate results compared to the solid element model with significantly reduced analysis time.

의미 정보를 이용한 이단계 단문분할

박현재,우요섭,Park, Hyun-Jae,Woo, Yo-Seop 한국정보처리학회 2000 정보처리논문지 Vol.7 No.9

단문분할은 한 문장에 용언이 복수개 있을 때 용언을 중심으로 문장을 나누는 방법이다. 기존의 방법은 정형화된 문장의 경우 비교적 효율적인 결과를 얻을 수 있으나, 구문적으로 복잡한 문장인 경우는 한계를 보였다. 본 논문에서는 이러한 한계를 극복하기 위해서 구문 정보만이 아니라, 의미 정보를 활용하여 단문을 분할하는 방법을 제안한다. 정형화된 문장의 경우와 달리 일상적인 문장은 무장 구조의 모호성이나 조사의 생략 등이 빈번하므로 의미 수준에서의 단문분할이 필요하다. 의미 영역에서 단문분할을 하면 기존의 구문 의존적인 방법들에서 발생하는 모호성을 상당수 해소할 수 있게 된다. 논문에서는 먼저 하위범주와 사전과 시소러스의 의미 정보를 이용하여 용언과 보어성분 간의 의존구조를 우선적으로 파악하고, 구문적인 정보와 기타 문법적인 지식을 사용하여 기타 성분을 의존구조에 점진적으로 포함시켜가는 이단계 단문분할 알고리즘을 제안한다. 제안된 이단계 단문분할 방법의 유용성을 보이기 위해 ETRI-KONAN의 말뭉치 중 25,000문장을 수작업으로 술어와 보어성분 간의 의존구조를 태깅한 후 본 논문에서 제안한 방법과 비교하는 실험을 수행하였으며, 이때 단문분할의 결과는 91.8%의 정확성을 보였다. Clausal segmentation is the method that parses Korean sentences by segmenting one long sentence into several phrases according to the predicates. So far most of researches could be useful for literary sentences, but long sentences increase complexities of the syntax analysis. Thus this paper proposed Two-Level Clausal Segmentation using sense information which was designed and implemented to solve this problem. Analysis of clausal segmentation and understanding of word senses can reduce syntactic and semantic ambiguity. Clausal segmentation using Sense Information is necessary because there are structural ambiguity of sentences and a frequent abbreviation of auxiliary word in common sentences. Two-Level Clausal Segmentation System(TLCSS) consists of Complement Selection Process(CSP) and Noncomplement Expansion Process(NEP). CSP matches sentence elements to subcategorization dictionary and noun thesaurus. As a result of this step, we can find the complement and subcategorization pattern. Secondly, NEP is the method that uses syntactic property and the others methods for noncomplement increase of growth. As a result of this step, we acquire segmented sentences. We present a technique to estimate the precision of Two-Level Clausal Segmentation System, and shows a result of Clausal Segmentation with 25,000 manually sense tagged corpus constructed by ETRl-KONAN group. An Two-Level Clausal Segmentation System shows clausal segmentation precision of 91.8%.

의미 정보를 이용한 이단계 단문분할

박현재(Hyun Jae Park),우요섭(Yo Seop Woo) 한국정보처리학회 2000 정보처리학회논문지 Vol.7 No.9

Clausal segmentation is the method that parses Korean sentences by segmenting one long sentence into several phrases according to the predicates. So far most of researches could be useful for literary sentences, but long sentences increase complexities of the syntax analysis. Thus this paper proposed Two-Level Clausal Segmentation using sense information which was designed and implemented to solve this problem. Analysis of clausal segmentation and understanding of word senses can reduce syntactic and semantic ambiguity. Clausal segmentation using Sense Information is necessary because there are structural ambiguity of sentences and a frequent abbreviation of auxiliary word in common sentences. Two-Level Clausal Segmentation System(TLCSS) consists of Complement Selection Process(CSP) and Noncomplement Expansion Process(NEP). CSP matches sentence elements to subcategorization dictionary and noun thesaurus. As a result of this step, we can find the complement and subcategorization pattern. Secondly, NEP is the method that uses syntactic property and the others methods for noncomplement increase of growth. As a result of this step, we acquire segmented sentences. We present a technique to estimate the precision of Two-Level Clausal Segmentation System, and shows a result of Clausal Segmentation with 25,000 manually sense tagged corpus constructed by ETRI-KONAN group. An Two-Level Clausal Segmentation System shows clausal segmentation precision of 91.8%.

의미 정보를 이용한 이단계 단문 분할 알고리즘

박현재(Hyun-Jae Park),이수선(Su-Seon Lee),우요섭(Yo-Seop Woo) 한국정보과학회 언어공학연구회 1999 한국정보과학회 언어공학연구회 학술발표 논문집 Vol.1999 No.10

THOR 더미 흉부 압입시험 결과에 기반한 최적의 안전벨트 경로 제안

박현재(Hyunjae Park),조아현(Ahyun Cho),김태웅(Taewung Kim),조민기(Mingi Cho),이태희(Taehee Lee),이수열(Sooyul Lee),진욱(Wook Jin) 한국자동차공학회 2019 한국자동차공학회 학술대회 및 전시회 Vol.2019 No.11

This paper investigated an optimal belt path for minimizing maximum chest deflection of THOR-M50 dummy. To understand structural characteristics of the thorax region, a series of thorax compression tests were performed. Based on the test results, an optimal belt path, which path through the mid-point of the upper IR-TRACC was suggested. The optimal belt path, then, was verified through belt pull tests. Since the belt pull experiment was performed under a simplified static condition, the validity of the optimum belt path need to be verified under dynamic loading conditions such as sled or vehicle crash tests.

모션 및 셧 정보의 통계적 분석에 의한 감정 관련 비디오 셧 검출

박현재(Hyun-Jae Park),강행봉(Hang-Bong Kang) 한국통신학회 2003 한국통신학회 학술대회논문집 Vol.2003 No.7

의미소를 이용한 한국어 오류 문자 교정 시스템

박현재(Hyun-Jae Park),박해선(Hae-Sun Park),강원일(One-Il Kang),손영선(Young-Sun Sohn) 한국지능시스템학회 2003 한국지능시스템학회 학술발표 논문집 Vol.13 No.2

기업의 조세부정예측모형에 관한 연구

박현재 ( Hyun Jae Park ),김갑순(교신저자) ( Kap Soon Kim ) 한국회계학회 2016 회계저널 Vol.25 No.3

본 연구는 국내 기업의 회계자료 및 기업특성을 이용하여 조세부정 정도를 추정하는 모형을 제시하고, 예측모형의 구체적인 활용방안을 설명하였다. 구체적으로, 2000년부터 2013년까지 세무조사로 적발되어 전자공시시스템(DART)에 공시한 12월 결산 상장법인과 대응표본을 대상으로 100회 무작위추출에 의한 단계적 로짓분석(stepwise logisticregression)을 실시하여 조세부정 예측모형을 추정하였다. 최종 예측모형에는 유효세율, 부채비율, 수출비율, 매출액, 회계이익과 과세소득의 차이, 재벌여부, 감사인 규모의 7개 변수가 포함되었다. 분석결과, 국내 상장기업들은 유효세율, 부채비율, 매출액이 높을수록 조세부정 가능성이 높았으며, 반면 수출비율, 회계이익과 과 세소득의 차이가 낮을수록 조세부정 가능성이 높은 것으로 나타났다. 또한 재벌에 소속되어 있으며 외부감사인이 Non-Big4인 경우에 조세부정 가능성이 높았다. 본 연구의 예측모형은 모든 기업을 비부정기업으로 가정하는 단순전략과 비교하여 총기대오류비용을 크게 감소시킬 수 있는 것으로 나타나 비용효율적임을 제시하였다. 재무제표와 기업특성 자료만을 필요로 하는 본 연구의 예측모형은 과세당국, 학계, 외부감사인, 투자자들이 특정 기업의 조세부정 가능성을 일차적으로 평가하는데 유용할 것으로 기대된다. Tax fraud affects the national budget to reduce the tax revenues of the country. Lisowsky(2010) is, U.S. Treasury(1999) with reference to the report, it reported that tax revenues that the federal government will be lost in the tax evasion has reached 10 billion dollars a year. In Korea, there is a trend that is collected additionally the number of tax audits and the amounts collected additionally associated with increased offshore tax evasion annually. Domestic and foreign tax authorities are making various efforts to prevent such these tax fraud. U.S. Internal Revenue Service(IRS) in 2000 to tax fraud transactions(tax shelter) dedicated to agencies(the Office of Tax Shelter Analysis, OTSA) established by the tax fraud monitoring and there. Even concluded in the domestic Foreign Account Tax Compliance Act(FATCA) from September 2015 agreed to strengthen offshore tax evasion blocked by the U.S. Internal Revenue Service(IRS) through the financial information exchange. Many studies theoretically explain and empirically analyze relevance of between of corporate tax burden level, financial characteristics, corporate governance, book to tax income differences and tax avoidance. In addition, previous studies related to tax evasion has focused to analyze the differences between the various properties compared to the corporate tax fraud caught by the companies. However, can be utilized in practice, decisions regarding models and tax evasion about to estimate the extent of tax evasion of specific companies, remains a substantial portion unsolved problem. In this study, while presenting a predictive model that can determine whether to tax fraud, the specific manner of utilization of the model is trying to explore. In particular, an attempt to estimate a more sophisticated predictive models, comprehensive consideration tax avoidance and financial characteristics that it has been confirmed that affect the tax evasion, ownership and governance structure characteristics, the external auditor of the properties are in the previous research did. Specifically, the effective tax rate, company size, profitability, ratio of assets investment, debt ratio, export ratio, sales, financial constraints, discretionary accruals, research and development expenses, of the difference between profit and taxable income on eleven numbers of financial characteristic variables, ownership interest rate, foreign interest rates, jaebul, whether three of ownership and characteristic variables of the governance structure, the auditor scale of one of the external auditor of the characteristic variables to the consideration stepwise logistic regression was utilized to derive the final predictive model. In order to eliminate the estimated arbitrariness of the estimation model, 50 percent of the entire sample to predict the estimation sample in the random sampling method, and the remaining 50 percent and holdout samples. Further, in order to solve one of the reliability issues due to random sampling, 100 times and randomly, and extracted the available variables in predictive model. By using the validation sample in order to verify the suitability of the estimated prediction model, to derive the tax fraud probability of tax fraud corporate and non-fraud corporate, tax fraud probability of tax fraud company has verified whether significantly higher. Further, we is trying to verification of the economic efficiency of tax fraud estimation model by comparing the total expected cost when using the predictive model or not by the methodology of Beneish(1997), Ko and Yoon(2006). This study develops a model to detect tax fraud using a sample of firms identified as tax fraud by the Financial Supervisory Service of Korea and characteristics of corporate for the period from 2000 to 2013. We find seven useful variables: tax expense/pretax book income(ETR); debt/total asset(LEV); export proceeds/total sales(EXPORT); log(total sales)(SALES); book-tax difference/total asset(BTD); jaebul(GROUP); auditor size(BIG4). Results suggest that Korean firms are more likely to manipulate taxable income when ETR, LEV, SALES are more larger and EXPORT, BTD are more smaller and these firms are GROUP and audited by Non-Big4. Compared with a naive strategy of classifying all firms as non-manipulators, our estimation model is expected to significantly reduce costs of misclassification. Tax regulator, academic, external auditors, investor, and other users of financial statements might use our model to screen potential tax fraud, to which they can allocate additional resources for more in-depth analysis.