• The Transactions of the Korea Information Processing Society
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• v.4 no.10
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• pp.2605-2614
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• 1997

Recently, we are concerned with effective service according as the demand increase for high speed data service. We can use high speed transfer and multiple traffic service on the ATM networks, so we concentrate on preventive-control method rather than reactive-control one. But it is possible to have low QoS and traffic congestion due to unpredictable traffic and burst traffic. Specially, ATM Forum has discussed to standardization of traffic management of ABR(Available Bit Rate) service. Because ABR traffic controls the flow of traffic using the feedback information and the current status information of cell, it allocates bandwidth systematically and dynamically to the user. In this paper, we propose a new Rate-based flow control scheme which adapted double threshold buffer idea. The double threshold buffer controls the traffic control by establishing two threshold in buffer.

• Korean Journal of Construction Engineering and Management
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• v.20 no.5
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• pp.42-51
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• 2019

The train operation institution establishes a transportation plan based on the forecast of transport demand and the ability of train vehicles to transport, and establishes a train operation plan accordingly. The train operation plan adjusts the intervals between trains, creates a timetable (train diagram) for trains, and establishes a plan for the operation of train vehicles used for train operation. The train operation institution shall establish a crew schedule to determine and place the crew members of the trains arranged in the diagram in order to enhance the efficiency of the operation management of the trains. In this study, the authors apply the neighborhood search method that satisfies the constraints at the phase of generating the crew diagram. This suggests a methodology for efficient management of crew schedule plan. The crew diagram generated in this study compared with the existing crew diagram in accordance with the actual operating train timetable, and verified the effectiveness of the suggested method.

• Korean Journal of Construction Engineering and Management
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• v.3 no.3 s.11
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• pp.58-65
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• 2002

University graduates from construction-related departments are undergoing serious difficulties in getting a job as construction companies are reluctant to employ new personnel due to the depression in the construction industry which has been downscaled in both domestic and overseas markets. In the situation is like this, statistics show that the percentage of employment among the university graduates is less than $25\%$, the unemployment problem in the construction sector has started to demand urgent countermeasures. This report anticipated demand and supply for technical man power in the field of construction in between 2002-2008. For preparation of an effectiveness of supply and demand plan on over-supplied in construction technical man power, this suggested expansion of SOC investment, induced into IT field of unemployed construction manpower, enlargement of overseas construction manpower And this considered an elastic operation of curriculum related to construction, and arranged an excess supply and demand of construction technical manpower, which has been considered to education that will meet with demand of enterprise, etc. on both side of quantity and quality simultaneously.

• Journal of the Korea Society for Simulation
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• v.25 no.4
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• pp.65-75
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• 2016

Unused spare parts of military equipments which have been kept in the warehouse for a long term have been recognized as wasting of defense budget which also decreased people's confidence in the field of national defence. It is known that overstock is caused by information distortion and bullwhip effect from downstream to upstream in the logistic support as is like business cases. After upgrading the logistic information system, it is possible for Army Logistics Command(ALC) to know demand information of end-user which is the key factor to reduce bullwhip effect. However, inventory is still overstocked and stock-out at the same time. Previous studies have not accounted for these phenomenons and have mainly focused on forecasting inventory level instead of budgetary process(budget period, PROLT, ASL/N-ASL). Thus, this study focuses on the information distortion, overstock and stock-out which caused by budgetary process in the logistic support with system dynamics and simulation.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.18 no.6
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• pp.187-193
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• 2018

There has been a gradual increase in the demand for the electric power in Korea. In order to meet the demand, power station should have technical functions with increased effectiveness. When accident happens in electric machinery at power stations, huge amount of economic losses and mulfunction of equipments occur. One of the accidents is a deteriorated cables operating power stations. In order to prevent cable accident in advance, we should monitor the insulation status of the cable. Cable accidents are resulting from the junctions. We have developed and installed a device in order to identify the status of junction part of power cable at Korea Western Power Co., Ltd.. We performed an accurate diagnosis for the stable utilization of junctions where the accidents occurs most frequently, and to increase the reliability. In this paper, we present the concepts of our device and the method of monitoring diagnosis for the stable use of junctions at cables predicting the life time of cables by analyzing the data obtained by the device. We also present the hardware aspect of the device we have developed.

• Journal of Korean Society of Transportation
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• v.23 no.3 s.81
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• pp.7-19
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• 2005

Mode choice Analysis is essential analysis stage in transportation demand forecasting process. Therefore, methods for calibration and forecasting of mode choice model in aspect of practical view need to be discussed in depth. Since 1980s, choice models, especially Logit model, are spread widely and rapidly over academic area, research institutes and consulting firms in Korea like other developed countries in the world. However, the process of calibration and parameter estimation for practical application was not clearly explained in previous papers and reports. This study tried to explain clearly the calibration process of mode choice step by step and suggested a forecasting mode choice model that can be applicable in real policy analysis by using household survey data of Pusan metropolitan are. The study also suggested a way of estimating attributes which was not observed during the household survey commonly such as travel time and cost of unchosen alternative modes. The study summarized the statistical results of model specification for four different Logit models as a process to upgrade model capability of explanation for real traveler's choice behaviors. By using the analysis results, it also calculated the value of travel time and compared them with the values of other previous studies to test reliability of the estimated model.

• Proceedings of the KSR Conference
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• 2011.05a
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• pp.1572-1581
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• 2011

Since 'The Act on Private Investment of The Infrastructure' was established in 1994, private investment as well as government's investment has been active on transport infrastructure. But investment of transport infrastructure has more risks than others due to overforecast of transport demand for ensuring project validity, and cost uncertainty arising from financial crisis, commodity prices and so on. In the case of Incheon international airport express, after 2 years and 6 months, Incheon international airport express is opened, Korail take over equity stake in private investor due to the problems of MRG(Minimum Revenue Guarantee) be contracted with private investor. Not only that, in other case of Yong-in light rail, it is ongoing for legal disputes between Yong-in local government and private investor on account of opening delaying. On current Investment Assessment System of Transport Infrastructure, Risk Management system on investment of transport infrastructure is inadequate because Sensitivity Analysis in economic efficiency have been performed on the simple method which only changes benefits, expense and social discount rate. For this reason, this study analyze risks for investment of transport infrastructure demand forecast, and rise to the management practice for every particular item.

• Proceedings of the Korea Water Resources Association Conference
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• 2005.05b
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• pp.797-800
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• 2005

RRFS를 개발하기 위해 NWSRFS 모형, SSARR 모형 및 TANK 모형 등에 대한 유출모형 현황 조사 및 특성 분석을 실시하여 실용성, 합리성, 적절성 중심의 기반모형으로 "수문학적 수문유출성분과 저수지 운영기법이 결합된" SSARR 모형을 선정하였다. 수계내 기상청, 건설교통부, 수자원공사에서 관할하는 강우관측소를 대상으로 관측시점부터 현재까지의 일강우자료 수집하였다. 12개 소유역에 대한 주요지점별 수위자료와 수위-유량 곡선식을 수집, 검토하여 수계 상하류에 위치한 수위관측소의 유출량 비교를 통해 적정 수위-유량곡선식을 선정하였다. 수계내 양수장, 보, 댐, 저수지 등 주요 수리시설물 현황조사를 실시 하였으며, 유역유출분석을 위한 유출모식도는 수자원공사내 DB 구조 및 유역유출 모의 시스템의 입출력 관계 등을 분석하여 구성하였다. 유출모형의 실시간 유역관리의 적용성을 파악하기 위해 과거 생공용수 및 농업용수의 수요량을 조사하였으며, 이들을 고려한 농업용수 수요 예측 시스템을 구축하였다. 유역유출 모의를 위해 SSARR모형의 매개변수 초기치 설정과 모형 보정을 위한 GUI를 개발하였다.

• Environmental and Resource Economics Review
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• v.15 no.5
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• pp.799-826
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• 2006

Combining recent advances in causal flows with time series analysis, relationships among eight North American natural gas spot market prices are examined. Results indicate that price discovery tends to occur in excess demand regions and move to excess supply regions. Across North America, the U.S. Midwest region represented by Chicago spot market is the most important market for price discovery. The Ellisburg-Leidy Hub in Pennsylvania is important in price discovery, especially for markets in the eastern two-thirds of the U.S. Malin Hub in Oregon is important for the western markets including the AECO Hub in Alberta, Canada.

• Journal of Digital Contents Society
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• v.13 no.3
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• pp.451-457
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• 2012

Recently, as the use of real time traffic information of a car navigation system increases rapidly with the development of Intelligent Transportation Systems (ITS), path search is getting more important. Previous algorithms, however, are mostly for the shortest distance searching and provide route information using static distance and time information. Thus they could not provide the most optimal route at the moment which changes dynamically according to traffic. Accordingly, in this study, Semantic Shortest Path algorithm with Reduction ratio & Distance(SSP_RD) is proposed to solve this problem. Additionally, a routing model based on velocity reduction ratio and distance and a dynamic route link map are proposed.