• Journal of Korean Society of Transportation
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• v.23 no.7 s.85
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• pp.99-110
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• 2005

Total travel cost of route which connects origin with destination (O-D) is consist of the total sum of link travel cost and route perception cost. If the link perception cost is different according to the origin and destination, optimal route search has limitation to reflect the actual condition by route enumeration problem. The purpose of this study is to propose optimal route searching formulation and algorithm which is enable to reflect different link perception cost by each route, not only avoid the enumeration problem between origin and destination. This method defines minimum unit of route as a link and finally compares routes using link unit costs. The proposed method considers the perception travel cost at both origin and destination in optimal route searching process, while conventional models refect the perception cost only at origin. However this two-way searching algorithm is still not able to guarantee optimum solution. To overcome this problem, this study proposed an orign based optimal route searching method which was developed based on destination based optimal perception route tree. This study investigates whether proposed numerical formulas and algorithms are able to reflect route perception behavior reflected the feature of origin and destination in a real traffic network by the example research including the diversity of route information for the surrounding area and the perception cost for the road hierarchy.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.9 no.5
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• pp.31-37
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• 2009

In the two-way relay channel, the relay employ Amplify-and-Forward (AF) or Decode-and-Forward (DF) protocol, and broadcast the network-coded signal to both user. In the system, DF protocol provides maximum throughput at low signal to noise ratio(SNR). On the other hand, at high SNR, AF protocol provides maximum throughput. The paper propose active transmission scheme which employ Amplify-and-Forward or Decode-and-Forward protocol based on received SNR at the relay over Two-way relay channel. The optimal threshold is investigated numerically for switching the protocol. Through numerical results, we confirm that the proposed scheme outperforms conventional schemes over two-way relay channel.

• Journal of Broadcast Engineering
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• v.11 no.4 s.33
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• pp.396-406
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• 2006

This paper proposes an omni-directional image generation algorithm with parametric image compensation. The algorithm generates an omni-directional image by transforming each planar image to the spherical image on spherical coordinate. Parametric image compensation method is presented in order to compensate vignetting and illumination distortions caused by properties of a camera system and lighting condition. The proposed algorithm can generates realistic and seamless omni-directional video and synthesize any point of view from the stitched omni-directional image on the spherical image. Experimental results show that the proposed omni-directional system with vignetting and illumination compensation is approximately $1{\sim}4dB$ better than that which does not consider the said effects.

• Journal of the Korea Society for Simulation
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• v.17 no.4
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• pp.133-142
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• 2008

AGV systems are widely used to increase the flexibility and the efficiency of the material handling systems. AGV systems are one of critical factors which determine the overall performance of the manufacturing systems. To this end, the optimal design for AGV systems is essential. Commercial simulation software is often used as an analysis tool during the design of AGV systems, however a series of procedures are desirable to simplify the analysis processes. In this paper, we present and develop the architecture for unidirectional AGV systems simulator which is able to consider approximate optimal unidirectional flow path and various operational parameters. The designed AGV systems simulator is based on JAVA, and it is developed to support designing approximate optimal unidirectional network by using Tabu search method. In addition, it enables users to design and evaluate AGV systems and to analyze alternative solutions easily. Simulation engine is consists of layout designer, AGV operation plan designer, and integrated AGVS layout designer. Users enter their system design/operation information into input window, then the entered information is automatically utilized for modeling and simulating AGV systems in simulation engine. By this series of procedures, users can get the feed back quickly.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.31 no.2
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• pp.79-85
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• 2018

A two-way pump can reduce costs by draining and circulating water out and into the drum of the washing machine using a single motor whereas a conventional one-way pump uses two motors for doing the same function. However, when the water is drained through the drainage outlet in the two-way pump casing, a backward or inhalation flow occurs and the water flows to the circulation outlet. Likewise, when the water is circulated, the backward flow or inhalation makes the water flow to the drainage outlet. In this study, design optimization of the two-way pump casing is performed to maximize its performance while improving backward flow and inhalation occurring inside of the pump casing. For this, design variables of the pump casing that mainly affect the performance of the pump such as flow rate and torque of the motor were selected through the analysis of mean. Using response surface models for the performances, the ratio of the flow rate to the torque was maximized with satisfying the constraints for the back flow and inhalation through design optimization.

• Proceedings of the KIPE Conference
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• 2016.07a
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• pp.389-390
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• 2016

본 논문에서는 마일드하이브리드 차량용 양방향 LDC의 동작 신뢰성 향상을 위해 2병렬 구성된 1.8kW급 LDC의 설계 및 제어에 대해 기술한다. 양방향 LDC 구현을 위한 최적 회로방법 및 병렬 구동을 위한 제어 방법에 대해 고찰하고 Working Sample 수준의 실험세트 제작내용 및 실험 결과를 제시한다.

• Proceedings of the KIPE Conference
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• 2016.07a
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• pp.44-45
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• 2016

본 논문에서는 DC Nano-grid를 위한 25kW급 고효율 양방향 컨버터를 개발하였다. 제안하는 양방향 컨버터는 넓은 입력전압 범위를 만족하기 위하여 Cascade 부스트-벅 컨버터의 구조로 하였으며 상용화된 SiC MosFET기반 3레그 IPM을 최적으로 사용하기 위해 2상 인터리빙 부스트 컨버터와 단상 벅 컨버터로 하였다. 또한 승 강압 모드에 따라 스위칭하는 스위치 개수를 감소시켜 스위칭 손실을 최소화 하였다. 25kW 시작품을 통해 14kW에서 효율 98.9%를 달성하였다.

• Proceedings of the KIPE Conference
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• 2013.11a
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• pp.155-156
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• 2013

최근 화석에너지 고갈과 환경문제, 전력대란을 격음으로써 신재생 에너지에 관한 관심이 많아지고 있다. 특히 연료전지를 이용하여 높은 신뢰성의 양방향 DC-DC컨버터가 요구되어 많은 연구개발이 진행되고 있다. 그중 컨버터를 병렬로 구동하여 전류리플을 줄이는 인터리브드 방식을 많이 사용하지만 인덕터의 부피, 비용이 증가하는 단점이 있다. 본 논문에서는 결합 인덕터를 이용한 Four-Phase 형태의 인터리브드 양방향 DC-DC 컨버터를 제안하고, 최적의 결합계수와 인덕터에 흐르는 전류 리플 저감을 PSIM 시뮬레이션을 통해 검증한다.

• Proceedings of the KIPE Conference
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• 2013.07a
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• pp.102-103
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• 2013

화석 연료의 고갈과 유가 급등으로 인해 자동차 업체에서는 친환경 차량 개발에 힘쓰고 있다. FCEV는 차량 구동용 전동기에 필요한 에너지를 연료전지를 통해 공급받게 된다. 하지만 연료전지의 특성상 연료전지와 배터리를 같이 사용하게 된다. 본 논문에서는 일반적인 Half-bridge 타입의 양방향 컨버터에 스위치를 추가하여 양방향 buck, boost가 가능한 컨버터를 설계하였다. 전동기 구동용 인버터는 전압형 인버터가 사용되는데 전압형 인버터에서 발생하는 출력은 데드타임과 스위칭 소자의 전압 강하에 의해 왜곡된 전압과 전류를 출력하게 되고 이러한 출력은 토크와 속도에 나쁜 영향을 끼치게 된다. 이러한 문제를 해결하기 위해 전동기의 속도에 따라 DC-link 전압을 가변하여 공급한다.

• Proceedings of the KAIS Fall Conference
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• 2010.05a
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• pp.381-384
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• 2010

최근 국가차원의 녹색성장정책에 의하여 대규모의 태양광발전 단지 뿐만 아니라 소규모의 태양광 전원이 수용가설비(배전계통)에 연계되어 운용되고 있는 실정이다. 그러나 현재의 수용가내 보호시스템의 기본적 조류는 상위계통에서 하위의 수용가로 한 방향으로 전력조류가 흐르고 있다는 것을 상정하고 있다. 이런 상황에서 수용가 측에 설치되어 있는 분산전원이 연계되면 역방향의 전력조류도 발생하므로 기존의 제어 보호 시스템으로 해결할 수 없는 상황이 발생하여 새로운 보호협조에 관한 연구가 요구된다. 특히 새로운 보호시스템 구축에 중요한 요소인 양방향 구간개폐기의 개발이 필수적 이다. 따라서 본 논문에서는 먼저 태양광전원이 배전계통에 연계되어 운용되는 경우, 기존의 구간개폐기의 문제점을 분석하고, 이를 해결할 수 있는 양방향 구간개폐기의 알고리즘을 제시한다.