• 전기학회논문지
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• 제65권12호
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• pp.2046-2052
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• 2016

Ramp metering is one of the most efficient and widely used control methods for an intelligent transportation management system on a freeway. Its objective is to control and upgrade freeway traffic by regulating the number of vehicles entering the freeway entrance ramp, in such a way that not only the alleviation of the congestion but also the smoothing of the traffic flow around the desired density level can be achieved for the maintenance of the maximum mainline throughput. When the cycle of the signal detection is larger than that of the system process, the density tracking problem needs to be considered in the form of the discrete-time system. Therefore, a discrete-time sliding mode control method is proposed for the ramp metering problem in the presence of both input constraint in the on-ramp and exogenous disturbance in the off-ramp considering the random behavior of the driver. Simulations were performed using a validated second-order macroscopic traffic flow model in Matlab environment and the simulation results indicate that proposed control method can achieve better performance than previously well-known ALINEA strategy in the sense that mainstream flow throughput is maximized and congestion is alleviated even in the presence of input constraint and exogenous disturbance.

• Industrial Engineering and Management Systems
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• 제15권1호
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• pp.19-31
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• 2016

A design method of the network for automated transporters mounted on rails is addressed for automated container terminals. In the network design, the flow directions of some path segments as well as routes of transporters for each flow requirement must be determined, while the total transportation and waiting times are minimized. This study considers, for the design of the network, the waiting times of the transporters during the travel on path segments, intersections, transfer points below the quay crane (QC), and transfer points at the storage yard. An algorithm, which is the combination of a modified Dijkstra's algorithm for finding the shortest time path and a queuing theory for calculating the waiting times during the travel, is proposed. The proposed algorithm can solve the problem in a short time, which can be used in practice. Numerical experiments showed that the proposed algorithm gives solutions better than several simple rules. It was also shown that the proposed algorithm provides satisfactory solutions in a reasonable time with only average 7.22% gap in its travel time from those by a genetic algorithm which needs too long computational time. The performance of the algorithm is tested and analyzed for various parameters.

• 전기학회논문지
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• 제57권4호
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• pp.576-581
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• 2008

Electricity Market in Korea can't provide locational price signal through energy price because energy market is CBP(Cost Based Pool) using uniform price. Generators don't want to locate in a densely populated load area(like the metropolitan area). Because they are paid more fixed cost in metropolitan area. This situation has loss and congestion occurred in power system. However energy market without price signal can't lead generator to the metropolitan. So, market participants should be provided price signal through the transmission price instead of energy price. This paper proposes transmission pricing method considering reliability cost in order to offer price signal. Also, it proposes the method to allocate the transmission cost to each transmission line user through a fair and a reasonable manner. The transmission price is decided by the reliability value of each line. If a transmission line of high reliability value is broke, users using that line will get a loss and a discomfort. So, it is fair that users using a transmission line of high reliability value pay more than the other users. Also, it is reasonable that a transmission line owner get paid more form users using that line.

• 한국항만학회지
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• 제11권1호
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• pp.13-28
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• 1997

Today the congestion problem is a problem for the most of the cities to solve. Especially, traffic congestion in the big cities is occurring regardless of the rush-hours. Because the transportation facilities secured in the big cities are very low, and the financial resources and sites for the expansion of new transportation facilities are also limited. Therefore the appropriate Transportation system Management(TSM) techniques which could improve the transportation system are absolutely required to solve the transportation problems instead of the expansion of the transportation facilities in the big cities. The purpose in this study was to review the travel characteristics on the Pretimed Signalized - Intersections under the study in Pusan area, construct the travel systems during the different time-periods based upon the travel characteristics reviewed, and finally suggest the optimal travel systems which could reduce the traffic delay and fuel consumption of the Pretimed Signalized - Intersections based upon the travel system constructed. Based upon the results, it could be concluded that the pretimed signal system based upon the on-peak periods should not be applied to all the different time-periods on the Pretimed Signalized - Intersections(PSI) to reduce traffic delay and fuel consumption, and increase the travel capacity on the intersections in Pusan area.

• 정보처리학회논문지C
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• 제14C권1호
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• pp.81-86
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• 2007

다양한 형태의 멀티미디어 서비스들은 서로 다른 QoS를 요구한다. 따라서, 서로 다른 멀티미디어 서비스를 효율적으로 지원하면서 동시에 우선순위가 높은 서비스의 QoS를 보장할 수 있는 효율적인 셀룰러/무선랜 오버레이 네트워크 관리기법에 대한 관심이 증가하고 있다. 본 논문에서는 효율적인 대역폭의 예약과 할당, 그리고 혼잡제어를 위한 통신 프로토콜을 통한 적응적 네트워크 관리기법을 제안하였다. 컴퓨터 시뮬레이션을 통하여 대역폭 관리를 위해 제안된 기존의 타 기법들과의 비곤 분석을 수행하여 제안된 방법이 다양한 네트워크 트래픽 상황에서 우수한 성능을 가지는 것을 확인할 수 있었다.

• 한국시뮬레이션학회논문지
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• 제11권4호
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• pp.43-55
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• 2002

Vessel traffic safety management means the managerial technical measures for improving the marine traffic safety in general terms. The main flow of vessel traffic safety management is that: 1) Traffic Survey, 2) Replay by Marine Traffic Flow Simulation, 3) Quantitative Assessment, 4) Policy Alternatives, 5) Prediction·Verification. In the management of vessel traffic safety, it is most important to establish assessment models that can numerically estimate the current safety level and quantitatively predict the correlation between the measures to be taken and the improvement of safety and the reduction of ship handling difficulties imposed on mariners. In this paper, the replay model for traffic flow simulation was made using marine traffic survey data, and the present traffic situation became replay in the computer. An attempt was made to rate the current safety of ports and waterways by applying the Environmental Stress model. And, as a countermeasure for traffic management, by taking of, the promotion of total traffic congestion in early morning rush hour, the correlation between traffic control rate and the reduction in ship handling difficulties imposed on mariners was predicted quantitatively.

• 전자공학회논문지
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• 제52권5호
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• pp.106-114
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• 2015

Wireless Body Area Network(WBAN)은 인체를 중심으로 다양한 의료 센서나 기기들을 연결하는 네트워크 표준으로써, 데이터의 전송률, 우선순위, 지연 시간등의 요구사항을 만족해야 한다. 본 논문에서는 네트워크의 상황에 따라 WBAN 데이터의 우선순위와 전송 지연 시간을 고려하여 WBAN 서비스의 성능을 향상할 수 있는 알고리즘을 제안한다. 이 알고리즘은 허브의 버퍼가 이전보다 혼잡해지면 데이터의 우선순위에 따라 데이터 제거 확률을 적용하여 데이터를 처리하고, 버퍼가 이전보다 원활해지면 데이터의 지연 시간을 고려하여 서비스한다. 기존 알고리즘과의 비교를 통해 제안한 알고리즘이 의료 데이터의 손실률을 낮추고 데이터의 지연 시간을 줄여 WBAN 서비스의 품질이 향상된 것을 확인할 수 있었다.

• 대한교통학회지
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• 제27권3호
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• pp.141-148
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• 2009

용량의 산정이 적합하지 못하다면 고속도로의 분석 및 예측에 잘못된 결론을 도출하게 된다. 도로의 용량을 일시적으로 크게 감소시키는 교통사고는 예측 불가능한 비반복정체를 발생시켜 혼잡관리가 어렵다. 따라서 본 연구는 사고발생시 속도에 따른 도로용량 파악을 목적으로 한다. 본 연구에서는 사고발생구간의 차량의 행태를 파악하여 교통류 속도에 따른 임계차두간격 산출모형과 최대통과교통량 산출모형을 구축하였다. 구축된 모형을 토대로 사고발생시의 고속도로용량감소율을 산정하였다. 그 결과 교통류의 속도가 40km/h일 때, 도로용량이 37%감소할 것으로 예측되었고, 다른 결과값은 본문에 수록하였다. 구축된 모형에 대한 검증은 제대로 수행할 수 없었지만 속도에 따른 도로용량감소율을 파악하고자 했다는데 본 연구의 의의를 두고 싶다.

• 한국정보과학회논문지:정보통신
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• 제30권2호
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• pp.260-269
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• 2003

기존의 분산 객체 미들웨어가 제공하는 RPC(Remote Procedure Call) 기반의 메시지전송 방식은 내부 오버헤드로 인해 실시간성을 요구하는 스트림 데이타의 전송에는 부적합하다. 그래서 OMG (Object Management Group)에서는 분산 환경에서도 실시간 스트리밍을 지원 할 수 있는 새로운 AV (Audio and Video) 스트림 서비스 참조 모델을 제안하였다. 그러나 이 모델은 오직 참조 모델이기 때문에 실제 구현 방법에 따라 재 정의해야 할 부분이 많이 남아 있다. 특히 실제 네트워크 환경을 고려한 혼잡 제어와 같은 기능이 없기 때문에 스트림 전송의 QoS를 제어할 수가 없다. 이러한 고려는 최근 연구되어 지고 있는 다양한 스트림 전송 플랫폼들이 가져야 할 고급 기능으로 전체 네트워크의 효율 증가를 위해서도 반드시 필요하다. 본 논문에서는 분산 환경의 장점을 최대한 부각시킬 수 있는 OMG의 스트림 서비스 참조 모델을 재 정의한 스트림 전송 플랫폼을 설계하고 구현하였다. 제안한 플랫폼은 스트림 전송을 위한 새로운 TCP-Friendly 프로토콜인 SRTP(Smart RTP)를 하부 구성 요소로 제공하며 이를 이용하여 본 플랫폼을 통한 스트리밍 응용들의 효율을 향상시켰다.

• 한국경영과학회지
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• 제3권1호
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• pp.31-46
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• 1978

Consider a time interval during which the demand for trips is fixed (e.g. the rush hour period). The traveller has a choice between various public modes, whose travel times and fares are fixed, and the automobile mode, for which travel time and cost depend on the volume of traffic flow on those roads, which are subject to congestion. We consider the equilibrium in terms of a representative travellerm, who choses for any trip the mode and route with the least combined money and time cost. When several (parallel) model or routes are chosen, then the combined cost of money and time must be equal among these. Our problem is first, to find the optimal flows of cars and of public mode carriers on the various links of their networks and second the optimal fares for trips by the variousmodes. The object is to minimize the total operating costs of the carriers and car plus the total time costs to travellers. The optimal fares are related to, but not identical with the dual variables of the underlying Nonlinear Program. They are equal to these dual variables only in the case, when congestion tolls on trips or on the use of specific roads are collected from automobile users. When such tolls are not collected, they must be passed on as subsidies to travellers using competing modes. The optimal fares of public modes are then reduced by the amounts of these subsidies. Note that subsidies are not a flat payment to public carriers, but are calculated on the basis of tickets sold. Fares and subsidies depend in general on tile period considered. They will be higher during periods of higher demand. When the assumption of fixed trip demand is relaxed, this tare system is no longer best, but only second best since too much traffic will, in general, be generated. The Free Rider Theorem states the following : Suppose road tolls can be charged, so that a best pricing system for public modes is posssible. Then there may exist free rides on some routes and modes, but never on a complete round trip.