• 대한기계학회논문집A
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• 제28권4호
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• pp.370-377
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• 2004

The density approach and the homogenization design method are representative methods in topology optimization problems. In the topology optimization in magnetic fields, those methods are applied based on the results of the applications In elastic fields. In this study, the density method is modified considering the concept of the homogenization design method. Also, the results of the topology optimization in magnetic fields by the modified density method as well as the homogenization method are compared especially focusing the change of the penalization parameter in the density approach. The effect of the definition of the design domain such as global/local design domain is also discussed.

• 한국컴퓨터정보학회논문지
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• 제11권4호
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• pp.189-196
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• 2006

상 디자인을 모델링 하는 ABS 방법은 물체의 기하학적 특성 속성 정보(점, 곡선, 기울기 등)를 기반으로 하는 모델링 방법으로서, 디자이너들에게 직관적으로 디자인할 수 있게 지원해 준다. ABS 모델링은 다각 패치에 대해 직각삼각형, 정사각형과 같은 항상 균일한 도메인을 가지고 모델링 한다. 이와 같은 방법은 모델링의 속도는 단축시킬 수 있으나 물체 모델링의 특성들과의 보간 과정에서 디자이너의 의도와 다른 오차가 발생 할 수 있다. 따라서 본 논문은 이러한 오차를 최소화하기 위하여 코드랭스 도메인 기법을 이용한 ABS 모델링 방법을 제안한다. 비 균일 도메인을 생성하는 방법 중 하나인 코드랭스 기법은 형상을 구성하는 각 속성들의 길이와 형태에 따라 도메인을 변화시키는 방법이다. 코드랭스 도메인 기법은 MEL을 이용하여 구현하였다.

• Journal of Power Electronics
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• 제8권3호
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• pp.201-209
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• 2008

This paper presents the modeling and design of a digital controller for a phase-shifted full-bridge converter (PSFBC) in a discrete-time domain. The discretized PSFBC model is first derived and then analyzed considering the sampling effect and the system parameters. Based on this model, the digital controller is directly designed in a discrete-time domain. The simulation and experimental results are provided to show the validity of the proposed modeling and controller design.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 합동 추계학술대회 논문집 정보 및 제어부문
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• pp.3-6
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• 2001

This paper presents optimal robust PID controller design method for second order systems to satisfy the design specifications in time domain. The parameters of PID controller are determinated by the weighting factors Q and R of cost function. It is suggested that the selection of Q and R matrix can be determinated by its relationship with the natural frequency of ITAE criterion.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 하계학술대회 논문집 B
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• pp.705-707
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• 2003

The design of multi-domain that considers all components of the electromagnetic systems such as air, iron, magnet, and coil is investigated using the topology optimization, interpolation method, and FEM. The design sensitivity equation for the topology optimization is derived using the adjoint variable method and the continuum approach. The proposed method is applied to the topology optimization of C-core actuator.

• 한국정보통신학회논문지
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• 제5권7호
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• pp.1346-1353
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• 2001

본 논문에서는 2차원 분모분리형 디지털 필터의 선계에 대한 알고리즘을 제안한다. 제안된 알고리즘은 진폭 특성과 위상특성으로 주어진 2차원 디지털 필터의 주파수 영역 설계명세조건을 특이치 분해를 이용하여 1차원 디지털 필터의 설계명세조건으로 분해한다. 따라서, 2차원 디지털 필터 설계문제는 1차원 디지털 필터의 설계 문제로 귀착되며 이는 계산적으로 유효하며 수치적으로 안정한 설계법으로 고려되며 설계 예로부터 유효성을 확인한다.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2005년도 추계학술발표대회 논문집
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• pp.173-178
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• 2005

In this paper, an efficient and robust analysis system for the flutter optimization of laminated composite wings has been developed using the coupled computational method based on the genetic algorithm. General three-dimensional doublet-lattice method is efficiently used to compute generalized aerodynamic forces of T-tail configuration in the frequency domain. Structural dynamic analyses of laminated composite T-tail models are conducted using finite clement method. The classical P-k flutter analysis technique is applied to effectively solve the aeroelastic governing equations in the frequency domain. Optimum design studies using genetic algorithm have been conducted in order to obtain maximum flutter stability of a composite T-tail configuration. The results show that flutter stability can be significantly increased using composite materials with proper optimum design concepts even for the same weight and shape condition. In the view point of engineering design, it is also importantly shown that the optimization of the vertical wing part is highly effective comparing to the optimization of horizontal wing part.

• 한국정밀공학회지
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• 제22권11호
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• pp.59-63
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• 2005

Since human listening is very sensitive when the sound hit him, the subjective index of sound quality is required. Therefore, at each situation of sound evaluation its composed with the sound quality factor. But, when substituting the level of one frequency band we could not see the tendency of substitution at whole frequency band during the sound quality evaluation. In this study a design of experiment is used. The frequency domain is divided into an equally 12 parts and each level of domain whether is given increase or decrease due to the change of frequency band based on 'sharp' and 'annoy' of the sound quality is analyzed. By using the design of experiment the number of test is reduce very effectively by the number of experiment and each band the main effect will be as a solution. The case of sound quality for 'sharp' and 'annoy' at each band, the change of band (increase or decrease of sound pressure or keep maintain) which will be the most effects on the characteristics of sound quality can be identify and this will be able to us to select the objective frequency band. Through these obtained results the physical changes of level at arbitrary frequency domain sensitivity can be adapted.

• 소성∙가공
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• 제9권4호
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• pp.362-371
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• 2000

In order to reduce weight of a high-speed railroad vehicle, the main body has been manufactured by hollow section extrusion using aluminum alloys. A porthole die has utilized for the hollow section extrusion process, which causes complicated die geometry and flow characteristics. Design of porthole die is very difficult due to such a complexity. The three-dimensional finite element analysis for hollow section is also an arduous job from the viewpoint of appropriate mesh construction and tremendous computation time. In the present work, mismatching refinement, an efficient domain decomposition method with different mesh density for each subdomain, is implemented for the analysis of the hollow section extrusion process. In addition, a modified grid-based approach with the surface element layer is utilized lot three-dimensional mesh generation of a complicated shape with hexahedral elements. The effects of porthole design are discussed through the simulation for extrusion of an underframe part of a railroad vehicle. An experiment has also been carried out for the comparison. Comparing the velocity distribution at the outlet with the thickness variation of the extruded part, it is concluded that the analysis results can provide reliable measures whether the die design is acceptable to obtain uniform part thickness. The analysis results are then successfully reflected on the industrial porthole die design.

• 대한인간공학회지
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• 제30권1호
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• pp.169-177
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• 2011

The aim of this study is to review previous studies on human errors in the service delivery processes. Service industry is sharply growing in the advanced countries. Many people are looking for something to contribute to the service industry. Although there are many research topics related to service domain that human factors and ergonomics specialists can do contribute, a few researchers are studying such topics. This paper indicated how previous researches on human factors and human errors have addressed the service domain, in order to prompt human factor study on the service domain. A variety of sources were inspected for literature reviews, including books and journals of managements, medicine, psychology, consumer behavior as well as human factor and ergonomics. The characteristics of human errors in the service domain were investigated. Human error studies in several service sectors were summarized such as medical service, automotive service operation, travel agent service and call center service. Until now, human factors community was not much interested in human errors in service domain. However, there is much space to contribute to service domain; human error identification, human error analysis and control of human error. The research of human error in service domain can provide clues to improve service quality. This paper helps to guide to identify human error of service domain and to design service systems.