• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1993년도 한국자동제어학술회의논문집(국내학술편); Seoul National University, Seoul; 20-22 Oct. 1993
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• pp.1018-1023
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• 1993

In mechanical structure design area, many FEM (Finite Element Method) packages are used. But the design using FEM packages depends on an iterative trial and error manner and general CAD systems cannot cope with the change of parameters. This paper presents a methodology for building a designing system of a mechanical structure. This system can generate the drawing for a designed structure automatically. It consists of three steps: generation of a structure by selection of the parameters, stress analysis, and generation of a drawing using CAD system. FEM module and parametric CAD module are developed for this system. Inference engine module generates the parameters with a rule base and a model base, and also evaluates the current structure. The parametric design module generates geometric shapes automatically with given dimension. Parametric design is implemented with the artificial intelligent technique. In older to the demonstrate the effectiveness of the developed system, a frame set of bicycle was designed. The system was implemented on an SUN workstation using C language under OpenWindows environment.

• 한국지능시스템학회논문지
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• 제5권4호
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• pp.12-17
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• 1995

지금까지 전문가들에 의해 만들어진 퍼지규칙들은 종종 모순되었고 불완전하였다. 본 논문에서 우리는 모순되지 않고 거의 완전한 퍼지규칙을 자동생성 하는 새로운 기법을 제안한다. 이러한 퍼지규칙의 자동생성은 제어경험으로 부터 퍼지규칙을 얻어내는 사람의 지식 축적과정을 모사한 방법이다. 이 방식은 기존의 방식들보다 보다간단하면서도 보다 효율적인 방법이다. 잘 조절된 파라메터상에서 우리의 방식이 전문가들보다 더욱 좋은 퍼지규칙을 생성함을 시뮬레이션을 통하여 보인다.

• Management Science and Financial Engineering
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• 제9권1호
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• pp.11-27
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• 2003

In this study, we propose a mathematical model based on the graph theory for the wavelength assignment problem arising in the design of SDH (Synchronous Digital Hierarchy) over WDM (Wavelength Division Multiplexing) ring networks. We propose a branch- and -price algorithm to solve the suggested models effectively within reasonable time in realistic SDH over WDM ring networks. By exploiting the structure of ring networks, we developed a polynomial time algorithm for efficient column generation and a branching rule that conserves the structure of column generation. In a computer simulation study, the suggested approach can find the optimal solutions within reasonable time and show better performance than the existing heuristics.

• 전기학회논문지
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• 제60권7호
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• pp.1372-1377
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• 2011

This paper proposes the control method of MPPT(maximum power point tracking) for the wind energy generation system using the duty ratio control of boost type DC-DC converter. For a lower cost and a higher reliability, the wind and the generator velocity sensors are removed. MPPT control is implemented by changing the duty ratio of the boost converter. Chain rule is applied by using each function. The grid side inverter is controlled to regulate unity power factor. The proposed control method was analyzed mathematically and verified by the computer simulation using PSIM.

• 전기학회논문지
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• 제58권10호
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• pp.1968-1975
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• 2009

The paper proposes a novel control algorithm for tracking maximum power of PV generation system.. The maximum power of PV array is determinated by a insolation and temperature. Prior considered the term in PV generation system is how maximum power point(MPP) is accurately tracked.. The paper proposes a fuzzy neural network(FNN) control algorithm so as to accurately track those maximum power points. The proposed control algorithm comprises the antecedence part of fuzzy rule and clustering method, multi-layer neural network in the consequent part. FNN has the advantages which are depicted both high performance and robustness in fuzzy control and high adaptive control in neural network.. Specially, it can show the outstanding control performance for parameter variations appling to non-linear character of PV array. In this paper, the tracking speed and the accuracy prove the validity through comparing a proposed algorithm with a conventional one.

• Journal of Power Electronics
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• 제19권6호
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• pp.1544-1553
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• 2019

The efficiency of photovoltaic generation systems depends on the maximum power point tracking (MPPT) technique. Among the various schemes presented in the literature, the incremental conductance (INC) method is one of the most frequently used due to its superb tracking ability under changes in insolation and temperature. Generally, conventional INC algorithms implement a simple duty-cycle updating rule that is mainly found on the polarity of the peak-power evaluation function. However, this fails to maximize the performance in both steady-state and transient conditions. In order to overcome this limitation, a novel regulated INC (r-INC) method is proposed in this paper. Like the compensators in automatic control systems, this method applies a digital compensator to evaluate the INC function and improve the capability of power tracking. Precise modeling of a new MPPT system is also presented in the optimized design process. A 120W boost peak power tracker is utilized to obtain comparative test results and to confirm the superiority of the proposed method over existing techniques.

• Journal of Welding and Joining
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• 제26권1호
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• pp.50-55
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• 2008

A low alloy-steel(2.25Cr-1.0Mo) has been widely used for boiler piping, header and tubes in high temperature and pressure conditions of the thermal power plant. It is common knowledge that the repair welding is permitted two or three times by customary practice rule, but there is no regulation to limit the number of repair welding base on the study heat-affected zone(HAZ), which is the weakest zone when repair welding is under taken, by experiments about the metallographic degradation and mechanical properties. Therefore, this study aims to verify the reliability of 5 times repair welding through conducting the experimental observation in the mechanical and the metallographic change on HAZ varying repair welding times. In results of the experiments, it is concluded that the reliability was kept in HAZ even up to the fifth repairs.

• 한국정보통신학회논문지
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• 제10권1호
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• pp.212-219
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• 2006

퍼지 논리 제어기(FLC : Fuzzy Logic Controller)를 사용할 때, 가장 중요한 것은 소속 함수의 범위를 정하는 것과 규칙의 형태를 결정하는 것이다. 소속 함수의 범위나 규칙의 형태는 자금까지 전문가가 임의로 정하는 방법을 사용하였다. 그러나 기존의 방법을 사용하면, 전문가의 주관적인 규칙과 소속 함수가 생성될 수 있고, 소속함수의 경우 최적의 범위를 정확히 예측하기 어려운 단점이 있다. 본 논문에서는 이런 단점을 보완하기 위해, 유전자 알고리즘을 사용함으로써 최적의 소속 함수와 규칙의 형태를 구하려 하였다. 제시하는 방법의 타당성을 검증하기 위해 자동차 주행 제어 문제에 적용시켜 보았다.

• 정보처리학회논문지D
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• 제17D권4호
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• pp.297-310
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• 2010

최근에 콘콜릭 테스트이라 불리는 새로운 테스팅 방법이 많은 관심을 받고 있다. 콘콜릭 테스팅은 높은 테스트 커버리지를 달성하기 위해 실제 프로그램 수행과 심볼릭 수행을 결합하여 테스트 데이터를 생성한다. CREST는 콘콜릭 테스팅을 구현한 대표적인 open-source 테스트 도구이다. 그러나 현재 CREST는 입력으로 정수형만 다룬다. 이 논문은 포인터형인 입력이 존재하는 경우에 자동 테스트 데이터 생성을 위한 새로운 규칙을 제안한다. 이 규칙들은 C 프로그램에서 주로 사용되는 다단계 스택 지향 포인터를 효과적으로 처리한다. 또한, 이 논문에서는 제안 된 규칙을 구현한 vCREST라 불리는 도구에 대해 기술하고 C 프로그램에 적용한 결과도 함께 기술한다.

• Journal of Information Technology Applications and Management
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• 제12권4호
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• pp.133-155
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• 2005

This Paper makes an attempt to suggest a process of automatically generating application software based on the Entity-Relationship model 1. The designer develops an E-R model of an real-world system. 2. The designer inputs the entity and relationship types, and attributes shown in the E-R model, and also the basic operations of the application system to the software generator. 3. The application generator produces database schema and link information between application programs, and then automatically generates a stereo-type application system. In order for the automated application generator to build the application system in a systematic way, four basic program generation rules have been suggested. A set of computer programs have been developed in order to show the applicability of the automated software generation process suggested in this paper. By following each rule with the generator, the designer can build an application in an efficient manner compared with traditional (manual programming) approaches. It has been demonstrated from the case study that the idea of applying an automated generator in systems development based upon the E-R model is feasible.