• Title/Summary/Keyword: bus demand

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Economies of Scale and Scope In Seoul's Urban Bus Industry (서울 시내버스운송업의 규모 및 범위의 경제성 분석)

  • 김성수;김민정
    • Journal of Korean Society of Transportation
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    • v.19 no.6
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    • pp.89-102
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    • 2001
  • Using a multiproduct translog cost function model, this paper examines the existence or absence of scale and scope economies in Seoul's urban bus industry. The Paper then conceptualizes that the bus firm produces three outputs (city, seat and local bus-kilometers) using low input factors(labor, capital, fuel and maintenance). Using 1996 annual observations for 81 Seoul's bus firms, the equation system consisting of a cost function and three input share equations is estimated with the nonlinear iterative Zellner method. The findings show that the cost function corresponding to a non-homothetic production technology with separability between local bus outputs and inputs adequately represents the structure of cost for Seoul's bus firms, and that the demand lot all input factors is quite inelastic with respect to their own price. On the other hand, nearly all firms experience mild overall economies or scale, but rather marked product-specific economies of scale with respect to all the three outputs. In addition, there appear to be substantial economies or scope associated with the joint production of city and seat bus services, while considerable diseconomies of scope associated with that of city and local bus services. These results indicate that the merger of smaller firms into larger firms with a fleet of approximately 200 buses would result in more cost-efficient bus services.

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Reasons for Violation of the Self Carfree Day Policy (승용차요일제 준수와 위반에 미치는 영향 분석)

  • Bin, Mi-Yeong;Jeong, Ui-Seok
    • Journal of Korean Society of Transportation
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    • v.28 no.4
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    • pp.61-73
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    • 2010
  • This research is to analyze reasons for violation of the Self Carfree day policy. It also analyzes satisfaction of the policy participation incentives. The results are that the violation rate is increasing if the drivers live in a zone which is highly energy consuming, which has low potential demand per bus stop and low trip generation per number of houses, which therefore requires more bus routes and bus services, and in which the drivers pay more car operating fees and show less tendancy towards participation even with the 5-10% oil price increase. The results are significant at the 0.05 level.

Carbody basic design for rubber tired AGT (고무차륜 경량전철의 차체 기본설계)

  • 이호용;홍재성;정종덕;이관섭
    • Journal of the Korean Society for Railway
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    • v.3 no.3
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    • pp.161-169
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    • 2000
  • AGT(Automated Guide-way Transit System) was introduced to satisfy the every increasing need for improved urban transportation. The AGT system is classified as medium distance and demand capacity mass transit being introduced for such area with inadequate passenger demand for railway construction but excessive demand for bus service. To decrease initial investment cost it is important that we have to secure the technology system of Light Rail Transit for Korea environment. By utilizing the finite element analysis, the result in this paper is enough to satisfy the strength whish is required. Also for the purpose of safety, it is decided the thickness and frame structure of the undeframe section through the analysis. It is known that carbody is no problem for required design conditions.

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Optimal Power Flow Considering Price Elasticity of Customer (소비자의 가격탄력성을 고려한 최적조류계산)

  • Joung, Sang-Houn;Shin, Young-Gyun;Kim, Bal-Ho H.
    • Proceedings of the KIEE Conference
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    • 2002.11b
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    • pp.372-374
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    • 2002
  • The Optimal Power Flow(OPF) is the optimization model that has different constraints and the specified objective function, which is very useful tool for efficient system and market operation in the competitive electricity market. The existed OPF models focus on the minimization of generation fuel cost under informed demand values at each bus Recently, the studies of OPF model with demand function considering the response behavior of customers in the deregulated electricity market have been executed. This paper implements the OPF model using demand function with specified price elasticity, and provides the analysis of related results.

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A Study on The Comparative Characteristics of Track-Guided Bus System (궤도버스시스템 특성비교연구)

  • 임성빈;지길룡
    • Journal of the Korean Professional Engineers Association
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    • v.30 no.4
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    • pp.88-98
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    • 1997
  • For Improving gradually inferior environment of public transportation system, it is necessary to introduce new transit System(NTS). NTS is defined as automated economicm system for it's operation . The Track Guided Bus System (TGBS) is one of the NTS, which is possible operating on the track or road surface and the system has actually many advantages. This study was concentrated on investigating the characteristics of TGBS, comparing to the other public transportation system and appraising the advantages of it on the benefit of the passenger side as well as investor, and then suggested applicable routes. As the result of the study, it is concluded that the advantage of this system is less transfering and initial low investment. Applicable route is the demand of passengers in the range of PPHPD 5,000~39,600, which is more than bus but not more than subway.

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Comparison of Fault Current Limiting Characteristics According to Facility in Power System (전력계통의 사고전류 저감 설비별 특성 비교)

  • Park, Hyoung-Min;Choi, Hyo-Sang;Cho, Yong-Sun;Lim, Sung-Hun;Hwang, Jong-Sun
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2005.05b
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    • pp.127-129
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    • 2005
  • We investigated the fault current limiting characteristics according to the various facilities in power system. Power systems are becoming larger and larger for meeting electric power demand. Therefore, the over-currents resulting from contingencies such as short circuits are increasing higher, which causes the ratings of circuit breakers(CBs) to increase. Upgrading or replacement of CBs is not difficult from the technical and economical point of view. Bus split is being adopted into a part of 154 kV power systems, but it has adverse effects such as overload to neighboring power systems, increased voltage fluctuation, and decreased power system stability. For 345 kV power systems, the bus split measure is not feasible and dc reactors are being suggested. The superconducting fault current limiter is a protection gear of new concept that limits fault current automatically in a few milliseconds. It can also provide the effect of CB capacity increase, relaxation of power machine criteria, enhancement in power system reliability, and flexible power system operation.

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Importance-Performance Analysis for Improving Demand Response Transport(DRT) System (수요응답형교통(DRT)의 활성화를 위한 중요도-실행도 분석)

  • Jang, Tae Youn;Kim, Jun Sung
    • The Journal of The Korea Institute of Intelligent Transport Systems
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    • v.17 no.3
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    • pp.46-58
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    • 2018
  • DRT should have higher positive benefits to become the public transit than the current backcountry buses having demand deficiency and operation problems. The study examines the factors for activating DRT through importance and performance analysis(IPA) and applies the IPA gap theory to find relationship between the current buses and DRT in the mixed operation area. As a result, the operation area is the urgent improving factor and the next ones are transfer related factors, on-time arrival, safe driving, operation time and vehicles. According to the gap theory to activate DRT and reduce the current bus system, in the case that performance is smaller than importance, the performance of transfer, operating time and area, and vehicles should be up. In the case that performance is higher than importance, the performance of luggage space, vehicle clean, safe driving, operator kindness, transfer, operating elements, and fare should keep going.

Short-Term Generation Scheduling Considering Transmission Line Capacity Limits (선로용량한계를 고려한 단기 발전계획)

  • 김준현;송현선;유인근
    • The Transactions of the Korean Institute of Electrical Engineers
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    • v.35 no.12
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    • pp.594-602
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    • 1986
  • This paper proposes an effective algorithm for short-term generation scheduling for the purpose of economic and secure operation of thermal power systems. Especially, in the procedure of solution by Dynamic Programming, Linear Programming is introduced to promote the possibility of optimal solution and the security of power systems, and evaluation of security function is improved by the application of seven step approximation of normal distribution. Several necessary considerations, that is, time dependent start-up and constant down cost of generating units, demand and spinning reserve constraints, minimum up and sown time constraints, the number of possible start-up of a generating unit in a d and the number of generating units which can be started up at the same time at the same bus, are also incoporated to elevate the usability and flexibility of the algorithm. Finally, the effectiveness of the proposed algorithm has been demonstrated by applying to the 6-gen. 21-bus model power system.

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A Seamless Control Method for Supercapacitor to Compensate Pulsed Load in DC Microgrid (직류 마이크로그리드에서 펄스형 부하 보상용 슈퍼커패시터 무순단 제어법)

  • Dam, Hung D.;Lee, Hong-Hee
    • The Transactions of the Korean Institute of Power Electronics
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    • v.23 no.4
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    • pp.265-272
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    • 2018
  • This paper proposes a new control method for the supercapacitor (SC) to compensate the pulsed load and to enhance the power quality of the DC microgrid. By coordinating the operating frequency, the SC is controlled to handle the surge current, while the low-frequency current component is dealt with by the remaining sources in the system. The operation mode of the SC unit is automatically changed based on the state of charge and DC bus voltage level. Meanwhile, the mismatch in the power demand is covered by the SC unit by regulating the DC bus voltage level. The effectiveness of the proposed method is verified experimentally by the prototype with two distributed generators and one SC unit.

A Study on Load Modeling with respect to the Change of Price in Competitive Electricity Market (전력산업 경쟁도입에 따른 요금변화에 대한 부하모델수립)

  • Han, Man-Hyung;Kim, Jung-Hoon;Choi, Joon-Young
    • Proceedings of the KIEE Conference
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    • 2000.07a
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    • pp.376-378
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    • 2000
  • The current worldwide electricity market introduced competition, which is breaking up the monopoly structure and also enforcing phased structural reform in South Korea. The change of the electricity charge from cost base to price base due to the introduction of the electricity market competition causes consumer to choose a variety of charge schemes and a portion of loads to be affected by this change. Therefore, in order to find a mathematical model of the sensitively-responding-to-price loads and reflect this to the DSM demand management, the price-sensitive load model is needed. Thus, this paper first proposes the composite price-sensitive load model that is expressed as a function of price, presents the methodology to estimate price-sensitive load model at each bus by bus load compositions.

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