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양천석,김갑식 대구산업정보대학 1995 논문집 Vol.9 No.2
The evolution of computer has seen the biggest turning point in the history of modern management. With the development of computer and other information technology, firms have been able to manage uncertainty to a certain extent, since decision makers have been able to consider many more contingent variables and obtain more effective and accurate information in more efficient ways. This isespecially true for network technology including VAN, LAN, WAN, MAN in today's more globalized and complicated business environment. Many firms put their efforts to figure out the possibility of increaing effectiveness of decision making and efficiency of daily operations by introducing network technologies. Some firms report successful experiences while the others are not. The level of success mostly determined by if they establish effective ways to utilize various network technoligies or not. This study has been done to propose ways for the effective usage of VAN. (1) The reliability of information from VAN must be fully guaranteed. (2) A VAN should be compatible and integrated with different VANs. (3) A VAN should be able to access and process various information media such as audio information, video information and text information. (4) A satisfactory after-service system is required. (5) Relevant regulations, guidelines and policies should be prepared and implemented effectively. (6) Set up a long-range plans for the training and eduction of VAN experts.
양천석(Chun-Suk Yang),윤인식(In-Sik Yoon),김경서(Kyung-Seo Kim) 전력전자학회 2005 전력전자학술대회 논문집 Vol.- No.-
This paper describes the design, construction and implementation of matrix converter based on space vector modulation technique. The matrix converter provides sinusoidal input and output wave forms, bidirectional power flow, controllable input power factor and a compact design, compared to the VSI with diode rectification stage at the input. The implemented prototype of matrix converter is built using the exclusive IGBT module and has an input filter, overvoltage protection circuit and commutation means for overcoming practical issues. The good results tested using an induction motor are also presented.
양천석(Yang, Chun Suk),정기호(Jung, Gi ho),정봉길(Jung, Bong Gil) 한국산업경영학회 2002 한국산업경영학회 발표논문집 Vol.2002 No.4
본 연구는 컨테이너 운송 분야에 대한 연구 수행의 기초적 연구로서, 컨테이너 운송에 대한 업무 흐름 소개와 이를 토대로 컨테이너 공로운송 분야의 문제를 체계적으로 접근하기 위한 수리적 모형을 제시한다. 제시되는 모형은 기존의 TSP (travelling salesman problem)와 VRP (vehicle routing problem)에서 활용되는 수리적 모형을 기반으로 컨테이너 운송의 제반 특성들을 반영하여 여러 가지 다양한 형태의 수학적 모형들을 분류한다. 아울러, 컨테이너 운송 문제와 대응할 수 있는 기존의 TSP와 VRP에서의 여러 알고리듬을 이용하여 본 연구에서 제시하고 있는 각각의 모형들에 대한 해법을 제시하고자한다. 본 연구에서는 실제 컨테이너운송업체에서 하루의 셔틀운송 수주물량을 처리하기 위해 운반차량대수를 추정할 수 있는 방법을 제안하고 셔틀운송 배차계획이 수립된 경우와 수립되지 않는 경우에서 실제 차량대수에 어떤 영향을 미치는지 시뮬레이션을 통해 비교해 보고자 한다. 끝으로 동적수송요구를 고려한 경우에서의 컨테이너 운송업체의 연중 운송차량대수의 결정방법에 대해서도 모형화를 통해 그 방법을 제시하고 수치 예를 통해 그 효과를 검증해 보고자 한다. At the present time, container transportation plays a key role in the international logistics. The efforts to increase the productivity of container logistics become essential for Korean trucking companies to survive in the domestic as well as global competition. We examine the workflow in container transportation and then develop mathematical models integrating the various operating and design characteristics of the containers. Several types of formulations are developed utilizing the standard formulations of well-known TSP(Traveling Salesman Problem) and VRP(Vehicle Routing Problem). We develop heuristic algorithms for the models and test them with real data. This paper presents an approach to determine the vehicle fleet size for container shuttle service in a stochastic work environment. The shuttle service can be defined as repetitive travel between the designated places during working period. Assuming that transportation time between any two service places and loading and unloading times are constant, a mathematical formulation is constructed and a solution algorithm is developed based on the well-known insertion heuristic. Simulations are carried out to investigate the applicability and validity of the algorithm compared with the real-word dispatching procedure considering the stochastic characteristics if container transportation service. This study suggests an approach for determining fleet size for container road transportation with dynamic demand in Korean. With the forecasted monthly container transportation data a year, a heuristic algorithm is developed to determine the number of company-owned trucks, mandated trucks, and rented trucks in order to minimize the expected annual operating cost, which is based on the solution technologies used in the aggregate production planning and the pickup-and-delivery problem. Finally the algorithm is tested for the problem how the trucking company determines the fleet size for transporting containers.
IEEE 802.11 무선랜에서의 동적 컨텐션 윈도우 관리기법
김정삼,양천석,Kim, Jeong-sahm,Yang, Chun-suk 한국정보과학회 2005 정보과학회논문지 : 기술교육 Vol.2 No.1
DCF에서는 binary slotted exponential backoff 기반의 CSMA/CA기법을 사용한다. 이 기법에는 컨텐션 윈도우의 크기가 매 충돌발생시 지수함수적으로 증가하기 때문에 충돌확률을 줄이는 데는 아주 효과적이다. 하지만 이로 인하여 데이터의 전송지연이 발생하는 원인이 되기도 한다. 본 논문에서는 채널의 활용도를 고려하여 컨텐션 윈도우의 크기를 동적으로 변화시키는 새로운 백오프기법을 제안한다. 이 기법은 프로토콜의 처리성능을 향상시키고 패킷의 평균 전송지연시간을 감소시킬 것이다. The Distributed Coordination Function (DCF)uses a Carrier Sense Multiple Access with Collision Avoidance (CSMA/Ch) scheme with a binary slotted exponential backoff. This exponential increasing CW is very effective to decrease the probability of collision. But, it sometimes acts as the cause of delay of data transmission. In this paper, we propose an adaptive backoff mechanism which tunes the value of CW parameter depending on the status of channel activity. Our mechanism increases the protocol throughput and reduces the average packet delay without any overhead.
김영문(Young Moon Kim),오익근(Ick Keun Oh),양천석(Chun Suk Yang) 한국호텔외식관광경영학회 2000 호텔경영학연구 Vol.9 No.2
The main purpose of this paper was to develop Internet-based electronic commerce(EC) system at the tourism industry in Korea. To accomplish the purpose of this paper effectively, first of all, theoretical background of Internet-based electronic commerce system was reviewed briefly. Second, research methodology was discussed with the following topics: (1) range of data collection, (2) data collection methods and period. (3) tools for the development of electronic commerce system. Third, development and implementation of electronic commerce system were discussed with following topics: (1) configurations of electronic commerce system, (2) implementation of electronic commerce system, (3) manor characteristics of electronic commerce system. (4) future developmental directions of electronic commerce system Finally, this paper was summarized and future research areas were suggested briefly.