• 대한전기학회논문지:전력기술부문A
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• 제50권4호
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• pp.166-171
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• 2001

Object-oriented programming is a solution for problems in the development, maintenance, and update of large software such as power system analysis software. However, many applications in the electrical industry critically depend on the computational efficiency of the implementation. In order to be flexible and reduce the computation time, this paper represents an efficient method for constructing a Jacobian matrix and for factorizing it, and designs the class hierarchy for power system. This method is applied to four different power systems for load flow calculation. The performance of the object-oriented program developed in C++ is assessed in computer simulation.

• Journal of Information Processing Systems
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• 제8권3호
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• pp.483-494
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• 2012

Many recent events, such as terrorist attacks, exposed defects in most sophisticated security systems. Therefore, it is necessary to improve security data systems based on the body or behavioral characteristics, often called biometrics. Together with the growing interest in the development of human and computer interface and biometric identification, human face recognition has become an active research area. Face recognition appears to offer several advantages over other biometric methods. Nowadays, Principal Component Analysis (PCA) has been widely adopted for the face recognition algorithm. Yet still, PCA has limitations such as poor discriminatory power and large computational load. This paper proposes a novel algorithm for face recognition using a mid band frequency component of partial information which is used for PCA representation. Because the human face has even symmetry, half of a face is sufficient for face recognition. This partial information saves storage and computation time. In comparison with the traditional use of PCA, the proposed method gives better recognition accuracy and discriminatory power. Furthermore, the proposed method reduces the computational load and storage significantly.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1993년도 하계학술대회 논문집 A
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• pp.248-250
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• 1993

In this paper, we assume that the dynamics of DC motor and nonlinear load are unknown. We train the inverse dynamic model of DC motor and nonlinear load using the neural network and construct speed control system based on the traind dynamic model and current control mode. Speed prediction scheme using neural network is also proposed the alleviate the time delay effect caused by the computation time of neural network. Simulation results show good performances of the control system. Finally, hardware configuration of the control system is outlined.

• Journal of Information Processing Systems
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• 제10권2호
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• pp.193-214
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• 2014

Load balancing is the major benefit of any distributed system. To facilitate this advantage, task duplication and migration methodologies are employed. As this paper deals with dependent tasks (DAG), we used duplication. Task duplication reduces the overall schedule length of DAG along-with load balancing. This paper proposes a new task duplication algorithm at the time of tasks assignment on various processors. With the intention of conducting proposed algorithm performance computation; simulation has been done on the Netbeans IDE. The mesh topology of a distributed system is simulated at this juncture. For task duplication, overall schedule length of DAG is the main parameter that decides the performance of a proposed duplication algorithm. After obtaining the results we compared our performance with arbitrary task assignment, CAWF and HEFT-TD algorithms. Additionally, we also compared the complexity of the proposed algorithm with the Duplication Based Bottom Up scheduling (DBUS) and Heterogeneous Earliest Finish Time with Task Duplication (HEFT-TD).

• 풍력에너지저널
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• 제4권1호
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• pp.68-74
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• 2013

Offshore wind farm is being increased since there are much trouble to develop onshore wind farm. But in the offshore, wind turbine wake does not dissipate less than onshore wind turbine because of low turbulence level. Thus this remained wake interacted to other wind turbine. This interaction reduces energy production in wind farm and have a bad influence on fatigue load of wind turbine. In this research, CFD model was constructed to analyze wake effect in offshore wind farm. A method that wind turbine rotor region was modelled in porous media was devised to reduce computation load and validated by comparison with Horns Rev measurement. Then wake interaction between two wind turbine was analyzed by devised porous model.

• Journal of international Conference on Electrical Machines and Systems
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• 제3권2호
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• pp.176-183
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• 2014

Three-phase four-wire distribution systems are used for both three-phase three-wire loads and single-phase two-wire consumer appliances in South Korea, Myanmar and other countries. Unbalanced load conditions frequently occur in these distribution systems. These unbalanced load conditions cause unbalanced voltages for three-phase and single-phase loads, and increase the loss in the distribution transformer. In this paper, we propose constant DC capacitor voltage control based strategy for the active load balancer (ALB) in the three-phase four-wire distribution systems. Constant DC capacitor voltage control is always used in active power line conditioners. The proposed control strategy does not require any computation blocks of the active and reactive currents on the distribution systems. Balanced source-side currents with a unity power factor are obtained without any calculation block of the unbalanced active and reactive components on the load side. The basic principle of the constant DC capacitor voltage control based strategy for the ALB is discussed in detail and then confirmed by both digital computer simulations using PSIM software and prototype experimental model. Simulation and experimental results demonstrate that the proposed control strategy for the ALB can balance the source currents with a unity power factor in the three-phase four-wire distribution systems.

• 한국수자원학회논문집
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• 제33권6호
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• pp.711-723
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• 2000

현재 사용되고 있는 소류사량 산정식들은 형식의 다양함과 관련변수들의 불일치로 각 공식의 특징을 파악하기 힘들며 사용된 관측자료가 다르기 때문에 상대적인 비교가 어렵다. 한편 산정식의 유도과정에서 사용되는 기본적인 가정들의 개선여지가 많은 것으로 판단된다. 이러한 문제점들을 해결하기 위하여 소류사량과 직접적으로 관련된 여러 무차원수들을 제시하고 그들간의 관계식을 도출하였으며 가장 적합하다고 판단되는 무차원수를 도입하여 형식의 통일을 기하였다. van Rijn이 제시한 관계식을 보다 간단한 형식으로 도출하여 새로운 소류사량 산정식을 개발하였다. Brownlie(1981)가 수집 정리한 관측자료와 개발식을 대비하여 경험 계수의 적합한 수치를 도출하였으며 광범위한 조건에서 유효하고 정밀도가 높은 조정식을 개발하였다.

• 한국멀티미디어학회논문지
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• 제7권2호
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• pp.264-271
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• 2004

인터넷기반의 클러스터 시스템 환경에서 부하공유 알고리즘은 네트워크의 특성 및 노드의 이질성에 따른 부하 불균형에 효과적으로 대처 할 수 있어야 한다. 본 논문에서 제안하는 효율적인 부하공유기법은 Weighted Factoring 알고리즘을 기반으로 스케줄러를 생성하고 여기에 적응할당정책과 개선된 고정 분할 단위 알고리즘을 적용하여 작업을 분배하는 것이다. 본 논문에서 적용한 적응할당정책은 상대적으로 작업속도가 느린 종노드의 작업을 빠른 종노드가 대신 수행하도록 하는 기법이며, 개선된 고정 분할 단위 알고리즘은 종노드의 계산시간과 데이터전송에 필요한 네트워크 통신시간을 겹치도록 하는 것이다. 제안된 알고리즘의 성능 평가를 위한 시스템 환경에서 멀티미디어 응용에 많이 사용되는 행렬의 곱셈 프로그램을 PVM을 통하여 실험한 결과, 본 논문에서 제안한 알고리즘이 NOW 환경에서 우수한 Send, GSS, Weighted Factoring 알고리즘보다 각각 75%, 79%, 그리고 17% 효율적임을 보였다.

• Structural Engineering and Mechanics
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• 제62권5호
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• pp.619-629
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• 2017

This paper focuses on the study of complete dynamic modeling and maximum dynamic load carrying capacity computation of N-flexible links and N-flexible joints mobile manipulator undergoing large deformation. Nonlinear dynamic analysis relies on the Timoshenko theory of beams. In order to model the system completely and precisely, structural and joint flexibility, nonlinear strain-displacement relationship, payload, and non-holonomic constraints will be considered to. A finite element solution method based on mixed method is applied to model the shear deformation. This procedure is considerably more involved than displacement based element and shear deformation can be readily included without inducing the shear locking in the element. Another goal of this paper is to present a computational procedure for determination of the maximum dynamic load of geometrically nonlinear manipulators with structural and joint flexibility. An effective measure named as Moment-Height Stability (MHS) measure is applied to consider the dynamic stability of a wheeled mobile manipulator. Simulations are performed for mobile base manipulator with two flexible links and joints. The results represent that dynamic stability constraint is sensitive when calculating the maximum carrying load. Furthermore, by changing the trajectory of end effector, allowable load also changes. The effect of torsional spring parameter on the joint deformation is investigated in a parametric sensitivity study. The findings show that, by the increase of torsional stiffness, the behavior of system approaches to a system with rigid joints and allowable load of robot is also enhanced. A comparison is also made between the results obtained from small and large deformation models. Fluctuation range in obtained figures for angular displacement of links and end effector path is bigger for large deformation model. Experimental results are also provided to validate the theoretical model and these have good agreement with the simulated results.

• 대한토목학회논문집
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• 제36권2호
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• pp.297-305
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• 2016

2015년부터 한국에서 시행된 "탄소배출권 거래제"로 인해 각 분야에서 환경문제에 대응하고자 하는 움직임이 커지고 있다. 특히 환경부하량의 정확한 산출이 어려운 건설 분야에서는 ISO 14040 Series의 LCA (Life Cycle Assessment)를 적용하여 환경부하량을 산출하고자 하는 움직임이 지속되고 있다. 본 연구에서는 PSC beam 교량의 시공중 발생하는 환경부하량을 전과정 평가(Life Cycle Assessment, LCA) 방법론을 기반으로 분석하였다. 총 34개의 교량을 대상으로 분석한 결과, 건설 자재별 환경부하량은 레미콘(53.3%), 선재(9.6%), 철근(7.8%), 시멘트(6.8%) 합판(5.5%), 에너지(5.2%) 순으로 도출되었으며, 환경 범주별 환경부하량은 지구온난화(45.5%), 자원고갈(30.4%), 인체독성(10.5%), 광화학산화물생성(8.9%) 순으로 도출되었다. 향후 LCA를 기획 및 설계 단계에서 도입한다면, 환경부하를 고려한 의사결정을 수행할 수 있을 것으로 기대된다.