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머신 러닝 기반 엔지니어링 메트릭을 고려한 차량용 임베디드 소프트웨어 결함 예측에 관한 실험적 연구
김대성(Daesung Kim),이성훈(Sunghoon Lee),성기태(Gitae Seong),김대성(Daesung Kim),이진환(Jinhwan Lee),배홍용(Hongyong Bhae) 한국자동차공학회 2020 한국자동차공학회 학술대회 및 전시회 Vol.2020 No.11
The complexity of automotive software has rapidly been increased with vehicular intelligence. Software fault prediction (SFP) can be helpful for improving the software quality and efficiently managing limited testing resources with early identification of faulty module. Many papers have been proposed to predict the potential software fault. Most of them are only considering source code attributes, as a result, it has been remained a challenge for industrial area to adopt which method is fit, robust, and provide most accurate model. In this paper, the framework is presented for SFP model design of the automotive steering system software obtained by mining historical repositories. For best performance model, we have additionally chosen engineering features like difficult level of requirements, competence of engineer, complexity of ports, test coverage with code metrics. Our model is evaluated with AUROC which is a performance measurement for classification problem. The Random Forest Classifier shows the best performance with 92.31%.
리던던시 환경에서 전기신호식 지능형 조향 시스템의 중재 제어 방법에 관한 연구
김대성(Daesung Kim),김대성(Daesung Kim),이진환(Jinhwan Lee),남궁주(Joo Namgung) 한국자동차공학회 2021 한국자동차공학회 부문종합 학술대회 Vol.2021 No.6
The reliability is described as a probability that a system will operate properly for a defined period of time without any failures, and it is considered as one of the important design attributes. In many safety critical devices, such as the steer-bywire (SbW) in automotive industry, some parts of the control system are considering redundant control system architectures, which are configured two identical controllers in a system, to ensure the higher functionality, reliability and intelligence which can recover from failures. Basically, redundancy is the duplication of critical components or functions of a system with the intention of increasing reliability of the system. Two identically configured controllers (one active, one backup or failsafe) should swap a role in the redundancy scheme within the deadline when a system failure is detected in active controller. A challenge of dynamic redundant systems is to determine a precise role as the active controller to operate a system, error detection of the active controller and how to take over to a backup controller in the defined time. Moreover, a role of each controller has to be independently protected to ensure mutual exclusion under functional safety requirements. This paper studies dynamic redundant architectures and arbitration control methods that can provide full fault-tolerance without any deviation of functionality even in the presence of faults. The evaluation of the proposed redundancy system is performed experimentally by actual test scenarios to show the practical implication of the system architecture.
Na 첨가량에 따른 CIGS 광흡수층의 결정성 변화에 관한 연구
김대성(Kim, Daesung),김재웅(Kim, Chaewoong),김대경(Kim, Daekyong),이덕훈(Lee, Duckhoon),김태성(Kim, Taesung) 한국신재생에너지학회 2010 한국신재생에너지학회 학술대회논문집 Vol.2010 No.11
CIS(CuInSe2)계 화합물 태양전지는 높은 광흡수계수와 열적 안정성으로 고효율 태양전지 제조가 가능하여 태양전지용 광흡수층으로 매우 이상적이다. 미국 NREL에서는 이러한 CIGS 태양전지를 Co-evaporation 방법으로 제조 20%이상의 에너지 변환 효율을 달성하였다고 보고하였다. CIGS 태양전지의 경우 기존의 유리 기판 대신 유연한 철강 기판을 사용해 태양전지를 flexible하게 제조 할 수 있다는 장점이 있다. 이러한 flexible 태양전지의 경우 기존의 rigid 태양전지의 적용분야 뿐만 아니라 BIPV, 선박, 장난감, 군용, 자동차등 더욱더 많은 분야에 활용이 가능하다. 하지만 flexible 태양전지에 사용되는 철강기판의 경우 기존의 유리 기판인 SLG에 함유되어 있는 Na이 첨가되어 있지 않아 별도의 Na 첨가가 필요하다. Na은 CIGS 광흡수층의 결정을 증가 시키며 태양전지의 전기적 특성을 향상시킨다. 이러한 Na이 없는 경우 효율이 감소한다. 따라서 flexible 태양전지 개발을 위해서는 Na 첨가에 대한 연구가 필수적이다. 본 연구에서는 Na의 증착 순서를 변화시켜서 CIGS 증착 전, 동시증착, CIGS 증착 후로 나누어 CIGS 광흡수층 결정성의 변화를 알아보고자 한다. Na의 두께를 5nm에서 500nm 까지 단계 별로 나누어 실험을 실시하였다. 이때 CIGS 광흡수층은 미국의 NREL과 같은 3 stage 방식을 이용하였다. 1st stage의 시간은 15분으로 고정하였으며 기판온도는 약 300?C로 고정 하였다. 2nd stage는 실시간 온도 감지 장치를 이용하여 Cu와 In+Ga의 조성비가 1:1이 되는 시간을 기준으로 Cu의 조성을 30%더 높게 조절하였으며 기판 온도는 약 640?C로 고정 후 실험을 실시하였다. 3rd stage의 경우 Cu poor 조성으로 조절하기 위해 모든 조건을 10분으로 고정 후 실험을 실시하였다. 기판은 Na의 영향만을 비교하기위하여 Na이 첨가되어있지 않은 corning glass를 사용하였다. 후면 전극으로 약 1{mu}m 두께의 Mo을 DC Sputtering 방법을 이용하여 증착 하였다. 각각의 Na 두께에 따른 CIGS 광흡수층의 특성을 분석하기 위해 FE-SEM, XRD 분석을 실시하였다.
김대성 ( Daesung Kim ),주민석 ( Minseok Chu ),김기상 ( Ki Sang Kim ),김흥태 ( Hung Tae Kim ),한복기 ( B G Han ),정재두 ( Chung Jae Du ) 한국정보처리학회 2006 한국정보처리학회 학술대회논문집 Vol.13 No.2
최근 인간 유전체 연구에 대한 관심이 증대되어 유전자원 정보에 대한 효율적 활용을 위한 정보 수집 및 관리 활동이 지속적으로 이루어지고 있다. 그러나 현재까지 연구된 보건의료분야 표준 코드체계들은 유전자원 정보 식별을 위한 적합한 표현방법을 고려하지 않아 유전자원 정보관리에 적용하기 어려운 문제점을 갖고 있으며, 현재 사용되는 식별체계 또한 기관에 따라 자체적으로 운영되고 있는 것이 현실이다. 따라서 이 논문에서는 보건의료 정보 관리에 적용되는 국내·외 표준 코드체계를 분석하고 유전자원 표준 코드체계 설계를 위한 정보 요구사항 및 기본방향을 제시하였다.
모듈화 허브베이링 유니트 다축 내구 시험평가 모드 개발
김대성(Daesung Kim),김기훈(Gihoon Kim) 한국자동차공학회 2007 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
Recently car manufacturers modularize components in order to save cost and constructing time. Modularizing components also helps the quality high due to minizing of tolerance. In case of wheel bearing, it is evolving from 1st gen. to 6th gen with combining neighborhood components such as hub, disk, knuckle and so on. In order to guarantee the durability performance of modularized hub bearing unit, the criterion for design and evaluation based on service loading condition are necessary. The criterion should describe service loading condition because it has much diverse range due to different driving area and culture. In this study, it was established durability evaluation criterion for modularized hub bearing unit. The main parameters causing system failure were founded through the analysis of failure examples. The loading condition including the parameters was measured from the vehicle test on over 60,000㎞ from various area. The measured data was used to make the durability evaluation criterion by extrapolation method based on operating profiles of each area. The block program test signal was designed to evaluate the durability of modularized hub bearing unit.
에탄올 연료 SI 엔진에서 에탄올-가솔린 연료 혼합비율에 따른 희박연소 및 배기 특성
김대성(Daesung Kim),윤승현(Seung Hyun Yoon),이창식(Chang Sik Lee) 한국자동차공학회 2009 한국자동차공학회 학술대회 및 전시회 Vol.2009 No.11
Lean combustion and exhaust emission characteristics in a ethanol fueled spark-ignited engine according to ethanol-gasoline fuel blending ratio were investigated in this paper. The test engine was 1591cc and 10.5 of compression ratio SI engine with 4 cylinders. In addition, lambda sensor and lambda meter were connected with universal ECU to control the lambda value which is varied from 1.0 to 1.5. The engine performance and lean combustion characteristics such as brake torque, cylinder pressure and rate of heat release were compared according to ethanol-gasoline fuel blending ratio. Furthermore, the exhaust emissions such as carbon monoxide (CO), unburned hydrocarbon (HC), oxides of nitrogen (NOX) and carbon dioxide (CO₂) were measured by emission analyzers. The results showed that the brake torque, cylinder pressure and the stability of engine operation were increased as ethanol blending ratio is increased. Brake specific fuel consumption (BSFC) was increased in higher ethanol blending ratio while brake speific energy consumption (BSEC) was decreased in higher ethanol blending ratio. The exhaust emissions were decreased as ethanol blending ratio is increased under overall experimental conditions, however, some specific exhaust emission characteristics were mainly influenced by lambda value and ethanol-gasoline fuel blending ratio.
자동차용 조인트/씨일 부품 내환경 시험을 위한 오염분체 특성 평가
김대성(Daesung Kim),김기훈(Gihoon Kim),강종수(Jongsoo Kang),정순오(Soonoh Chung),이영제(Youngze Lee) 한국자동차공학회 2008 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
The most frequent trouble parts in automotive suspension system are seals and joints. Their fault is critical not in safe but in satisfaction of consumers. They are made of rubber or plastic material. The life of rubber and plastic parts is affected by not only loads but environmental conditions such as temperature, ozone, UV, contaminants and so on. In this study, the contaminants affecting wear of seal and joints was evaluated. From test in China, the contaminants absorbed in suspension system was collected. The chemical composition and particle size of them was analyzed and compared to test dust in KS standard in order to acquire the fundamental data for standardized environmental durability test of seals and joints.
Dot 패턴 기반 컬러 태양광 모듈의 심미성 향상 및 고효율화 연구
김대성(Kim Daesung),양연원(Yang Yeonwon),유보연(Ryu Boyeon),김민규(Kim Mingyu),주진(Ju Jin),조성배(Cho Sungbae) 한국태양에너지학회 2021 한국태양에너지학회 논문집 Vol.41 No.4
The solar energy market in South Korea has shown a high growth rate, with an expectation of reaching 4 GW in 2022. Plans to expand BIPV (Building Integrated Photo Voltaic) when new buildings are created have recently been increasing in preparation for a mandatory zero energy policy. Currently, zero-energy construction is mandatory for public buildings of over 1,000 ㎡. By gradually expanding the scope of the target, the mandatory designation of all buildings of over 500 ㎡ as zero-energy buildings is expected to occur by 2030. In this paper, we describe an efficiency optimization study based on the width ratio, coverage rate, and color of the patterns for an aesthetic improvement and high efficiency of the product. We aim to develop 50 W dot-pattern-based color solar modules that can improve the artistry and value of buildings when BIPVs are installed. A commercialization model is needed to expand the BIPV product line, which can add design and functional elements in the domestic solar power market, which is expected to grow at rates of tens of gigawatts in the future.