• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1995년도 Proceedings of the Korea Automation Control Conference, 10th (KACC); Seoul, Korea; 23-25 Oct. 1995
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• pp.240-243
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• 1995

In excavating tunnels, shield tunneling machines having many cutters on their cutter planes are used. Not many observation data being available in the detection system, optimal observation policy is very important. From this viewpoint, we previously considered the optimal location of acoustic sensors on the cutter plane and also the optimal observation policy for the case where three receiving transducers were used, and showed that the optimal sensor location was given as arbitrary equally-spaced points on the cutter plane circle, and that the optimal rotating angles were also found to be arbitrary. In application, however, it is often difficult to locate sensors at arbitrary positions or to use three sensors from the viewpoints of machine structure and cost. This paper considers the optimal observation policy for detecting anomlous plane objects for the case where two receiving transducers are used and the case where three receiving transducers are located only on a diameter of the cutter plane.

• 소성∙가공
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• 제15권5호
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• pp.347-353
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• 2006

The delivery system such as sprue, runner and gate is a waste of resin in injection molding operation. In this study the reduction of runner size has been investigated using injection molding CAE softwares, Moldflow and Moldex3D, and commercial CFD Softwares, Fluent and Polyflow. To verify the computational results experiment was performed. There were three considerations in deciding optimal runner size in this study: minimum pressure at the gate that makes resin fully filled in the cavity, minimum runner size that compensates shrinkage of resin in the cavity, and frozen layer thickness formed in the runner during injection. Through the computer simulations the optimal runner size that satisfies those three considerations has been decided. Although the computational results among the softwares were slightly different, it was enough to predict the optimal runner size. The previous runner diameter was 8 mm and predicted optimal size was 5 mm. This was verified by injection molding experiment. Thus, the way of CAE application in deciding optimal runner size adapted in this study would be appropriated.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2006년도 춘계학술대회 논문집
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• pp.363-366
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• 2006

The delivery system such as sprue, runner and gate is a waste of resin in injection molding operation. In this study the reduction of runner size has been investigated using injection molding CAE softwares, Moldflow and Moldex, and commercial CFD Softwares, Fluent and Polyflow. To verify the computational results experiment was performed. There were three considerations in deciding optimal runner size in this study: minimum pressure at the gate that makes resin fully filled in the cavity, minimum runner size that compensates shrinkage of resin in the cavity, and frozen layer thickness formed in the runner during injection. Through the computer simulations the optimal runner size that satisfies those three considerations has been decided. Although the computational results among the softwares were slightly different, it was enough to predict, the optimal runner size. The previous runner diameter was 8 mm and predicted optimal size was 5 mm. This was verified by injection molding experiment. Thus, the way of CAE application in deciding optimal runner size adapted in this study would be appropriated.

• 한국수자원학회논문집
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• 제38권5호
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• pp.415-425
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• 2005

본 연구에서는 준분포형 장기유출 모형인 SWAT(Soil and Water Assessment Tool)을 적용하는 경우 유출 결과의 정도를 확보하기 위한 강우계 밀도 및 소유역의 규모를 파악하였다. 다차원 강우모형인 WGR모형(Waymire 등, 1984)에 의하여 모의 발생된 강우를 SWAT모형을 통하여 유출해석한 후 다양한 소유역 규모 및 강우계 밀도에 대해 유출 오차를 분석하는 방법을 사용하였으며, 연구결과 대상유역인 용담댐 유역의 경우 적정 소유역의 평균면적 및 강우계 1개가 대표하는 면적의 적정규모는 모두 $80km^2$로 파악되었다.

• 대한전자공학회논문지SD
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• 제46권12호
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• pp.96-104
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• 2009

일반적인 동적 전압 조절(dynamic voltage scaling)의 가정과는 다르게 실제 시스템에 있어서는 응용 프로그램의 성능이 프로세서의 동작 속도에 정비례하지 않는다. 본 연구에서는 응용 프로그램의 성능과 동작 속도의 관계를 실측을 통하여 수치화하여 응용 프로그램의 특성을 모델링하고 각기 다른 응용 프로그램 특성 계수를 갖는 태스크 집합에 적합한 스케줄링 기법을 제시하였다. 또한, 모든 태스크의 단위 수행시간 변화에 따른 에너지의 변화량이 동일해야 에너지 최적이 된다는 해석적인 정리를 제시하였다. 본 연구에서 제시하는 스케줄링 기법은 이러한 해석적 정리에 기반을 두기 때문에 항상 각 태스크에 시스템 에너지 최적이 되는 조절비를 제시한다. 합성 태스크 집합을 이용한 실험결과에서 기존 연구 대비 약 7%의 추가적인 에너지 절감 효과를 얻을 수 있었다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 추계학술대회
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• pp.1340-1345
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• 2003

In this paper, an integrated optimal design software system for structural components has been developed which interfaces existing commercial codes for CAD, CAE and Optimization. They include specialized optimal design software codes such as iSIGHT and VisualDOC, optimization module imbedded in CAD software developed by CAD developers, and optimal design software systems based on API of commercial CAD software. The advantages of the CAD imbedded optimal design approach and those of specialized optimal design software are taken to develop the system. The user defines optimal design formulation in the user interface for problem definition in the CAD control stage, where design variables are directly selectable from the CAD model and various properties and performance functions defined. The commercial CAD codes, Open I-DEAS are used for the development. The resulting software is minimally connected to CAD and CAE systems while keeping maximum independence from each other. This assures flexibility and freedom for problem definition. Fatigue life optimization is taken as a nontrivial application area. As a specific example, the shape design of a knuckle part of an automobile is performed, where the minimum fatigue life over the material domain in terms of the number of cycles of a curb strike are maximized under the constraint of not exceeding the current mass. The fatigue life has been improved by four times of the initial life. The developed software is illustrated to maintain the advantages of existing optimal design software systems while improving independency and flexibility.

• 품질경영학회지
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• 제17권1호
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• pp.69-81
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• 1989

This study is concerned with a job sequencing method using the concept of sampling technique in the case of Job Shop. This is the follow study of Kang and Ro (1988) which examined the possibility of application of sampling technique to determine the Job Sequence in the case of Flow Shop. Not only it is very difficult, but also it takes too much time to develop the appropriate job schedules that satisfy the complex work conditions. The most job sequencing algorithms have been developed to determine the best or good solution under the special conditions or assumptions. The application areas of these algorithms are also very narrow, so it is very hard to find the appropriate algorithm which satisfy the complex work conditions. In this case it is very desirable to develop a simple job sequencing method which can select the optimal job sequence or near optimal job sequence with a little effort. This study is to examine the effect of sampling job sequencing which can select the good job of 0.01%~5% upper good group. The result shows that there is the sets of 0.05%~23% job sequence group which has the same amount of performance measure with the optimal job sequence in the case of experiment of N/M/G/$F_{max}$. This indicates that the sampling job sequencing method is a useful job sequencing method to find the optimal or good job sequence with consuming a small amount of time. The results of ANOVA show that the only one factor, number of machines is the significant factor for determining the job sequence at ${\alpha}=0.01$. It takes about 10 minutes to compare the number of 10,000 samples of job sequence by personal computer and it is proved that the selection rate of the same job sequence with optimal job sequence is 23.0%, 3.9% and 0.065% in the case of 2 machines, 3 machines and 4 machines, respectively. The area of application can readily be extended to the other work condition.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2004년도 ICCAS
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• pp.1999-2004
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• 2004

Collision avoidance for the aircraft can be stated as a problem of maintaining a safe distance between aircrafts in conflict. Optimal collision avoidance problem seeks to minimize the given cost function while simultaneously satisfying the constraints. The cost function can be a function of time or input. This paper addresses the trajectory time-optimization problem for collision avoidance of the unmanned aerial vehicles. The problem is difficult to handle, because it is a two points boundary value problem with dynamic environment. Some simplifying algorithms are used for application in on-line operation. Although there are more complicated problems, by prediction of conflict time and some assumptions, we changed a dynamic environment problem into a static one.

• 한국전자통신학회논문지
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• 제2권3호
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• pp.174-179
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• 2007

본 논문에서는 유전자 알고리듬을 이용하여 전력, 면적, 속도를 고려한 저전력 모듈 선택을 제안한다. 제안한 알고리듬은 최적의 모듈 선택을 통해서 전력 소모를 최소화 할 수 있다. 비교 실험에서는 최적 모듈 선택을 고려한 알고리듬은 최대 전력 감소량은 26.9 %를 얻을 수 있었고, 반면에 최소 전력 감소량은 9.0% 얻었다. 모든 벤치마크 평균 전력 감소량은 15.525%가 되었다.

• 무역상무연구
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• 제49권
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• pp.111-137
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• 2011

UCP 600 Article 14(b), providing rules for the period of the examination of documents, is a radical reorganization of UCP Article 13(b). The provision changes the period of time to a maximum of five banking days instead of reasonable time. One of the critical problems giving rise to the difficulty in interpretation and application is the question of fact that there may be two possible conflicting options in determining the time of checking documents presented. The one doctrine is fixed time(safe harbor) standard, and the other is hidden reasonableness standard. This study analyzes which option should be adopted for the optimal application standard by welfare effect methodology using consumer surplus approach and suggests that safe harbor standard should be optimal solution to the determination of period of examination of documents presented in letter of credit regime.