• 대한교통학회지
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• 제8권1호
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• pp.17-24
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• 1990

The first-best pricing rule which achieves economic efficiency is to equate price with marginal cost. Since public transport demand is derived from some other demand, the user cost as well as the producer cost are considered in its pricing. The optimal price is derived from a derivative of the total social cost with respect to demand. In case of the bus, if there is enough capacity for demand increase, the optimal price is determined by the marginal producer cost resulting from bus sped decrease and by the marginal user cost resulting from journey time increase. Both are caused by boarding and fare collecting time of an additional passenger. Because of the budget constraints, the marginal cost pricing cannot be applied in practice. Then price discrimination as the second-best pricing is introduced. The Ramsey pricing, to charge different prices for different demand elasticities, and nonuniform prices such as travelcards can be applied. However, there is practical difficulty in implementing these prices because of great informational requirements, the costs of administration and the ease to users.

• Structural Engineering and Mechanics
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• 제71권2호
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• pp.139-151
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• 2019

In a project schedule, it is possible to reduce the time required to complete a project by allocating extra resources for critical activities. However, accelerating a project causes additional expense. This issue is addressed by finding optimal set of time-cost alternatives and is known as the time-cost trade-off problem in the literature. The aim of this study is to identify the optimal set of time-cost alternatives using a multiobjective teaching-learning-based optimization (TLBO) algorithm integrated with the non-dominated sorting concept and is applied to successfully optimize the projects ranging from a small to medium large projects. Numerical simulations indicate that the utilized model searches and identifies optimal / near optimal trade-offs between project time and cost in construction engineering and management. Therefore, it is concluded that the developed TLBO-based multiobjective approach offers satisfactorily solutions for time-cost trade-off optimization problems.

• KIEE International Transactions on Power Engineering
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• 제11A권4호
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• pp.21-26
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• 2001

As competition is introduced in the electricity supply industry, congestion becomes a more important issue. Congestion in a transmission network occurs due to an operating condition that causes limit violations on the transmission capacities. Congestion leads to inefficient use of the system, or causes additional costs (Congestion cost). One way to reduce this inefficiency or congestion cost is to control the transmission flow through the installation of UPFC (Unified Power Flow Controller). This paper also deals with an optimal siting of the UPFC for reducing congestion cost by using shadow prices. A performance index for an optimal siting is defined as a combination of line flow sensitivities and shadow prices. The proposed algorithm is applied to the sample system with a condition, which is concerning the quadratic cost functions. Test results show that the siting of the UPFC is optimal to minimize the congestion cost by the proposed algorithm.

• 대한치과의사협회지
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• 제52권7호
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• pp.416-424
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• 2014

The purpose of this study is to analyze the cost of dental implant by top-down method and, on that basis, to provide salient information for the suitable standard of dental insurance fee. A survey data and accounting documents from 36 samples of dental clinics secured with the organisation authority are used and analysed for extracting the representative sample of dental clinic. A researcher visited the dental clinics in person and conducted additional interviews in the omitted case of accounting documents. A dental implant cost by top-down method was estimated to 1,430,000 won. Labor cost accounted for 43% of the total cost structure, ranking it 1st and, management cost, material cost and interest cost on investment cost in order are investigated. Labor cost counts of the total cost that shows the similar aspect to the existing result. Cost in cost accounting of medical care would be used for the judge that cost pursed value for dental service, not price or fee.

• 한국태양에너지학회:학술대회논문집
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• 한국태양에너지학회 2011년도 추계학술발표대회 논문집
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• pp.40-44
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• 2011

Recent studies in crystalline silicon solar cell fabrication have been focused on high efficiency and low cost. However, the rising of the cost results in additional processes to approach high efficiency. The fabrication process also becomes complicated with additional technologies. In this paper, we studied the selective emitter formation with phosphorous paste to improve the conversion efficiency. Selective emitter formations like two-step diffusion or etch-back method require at least one more step compared in the conventional line since heavily and lightly doped area was needed to form separately.However,one-step diffusion process is the method diffusing heavily and lightly doped area at the same time only with additional screen-printing step. This study lays the foundation for the simple way to form the selective emitter.

• 한국건설관리학회논문집
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• 제20권5호
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• pp.21-30
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• 2019

최근 전 세계적으로 지구온난화에 따른 이상기온과 화석연료 고갈 등 환경과 에너지문제는 인류의 생존을 위협하는 중대 과제로 대두되고 있다. 이에 따라 건축물 에너지 절감 및 온실가스 감축에 획기적으로 기여할 수 있는 혁신적인 건축물로서 제로에너지빌딩에 대한 관심이 높아지고 있다. 그러나 시장에서는 추가되는 건설비용은 제로에너지 인증 활성화에 큰 걸림돌이 되고 있다. 본 연구에서는 일반적인 민간 분양아파트를 연구의 대상으로 선정하고 초기 설계단계부터 제로에너지 인증을 위한 세부 요소들을 친환경주택 건설기준에 근거하여 제시하였으며, 인증 세부요소들의 비용효율분석을 통해 적정 가산비용을 제시하였다. 아직까지 기술수준과 물리적인 한계로 인하여 공동주택에서는 3등급까지만 인증이 구현 가능 한 것으로 분석되었다. 또한 생애주기동안 비용추이를 검토해본 결과 아직까지 제로에너지빌딩 5등급의 경우에서만 준공 후 13년 이내 모든 비용의 회수가 가능한 것으로 검토되었다. 앞으로 발주예정인 공동주택 사업 검토 시 본 연구에서 제시된 추가사업비가 적절히 반영되어 제로에너지빌딩 인증 활성화에 기여하고자 한다.

• Journal of Electrical Engineering and Technology
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• 제2권4호
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• pp.500-504
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• 2007

In this paper, the induction motor rotor fault diagnosis system using current signals, which are measured using axis-transformation method, and speed, which is estimated using current information, are presented. In inverter-fed motor drives unlike line-driven motor drives the stator currents have numerous harmonics components and therefore fault diagnosis using stator currents is very difficult. The current and speed signal for rotor fault diagnosis needs to be precise. Also, high resolution information, which means the diagnosis system, demands additional hardware such as low pass filter, high resolution ADC, encoder and etc. Therefore, the proposed axis-transformation and speed estimation method are expected to contribute to low cost fault diagnosis systems in inverter-fed motor drives without the need for an encoder and any additional hardware. In order to confirm validity of the developed algorithms, various experiments for rotor faults are tested and the line current spectrum of each faulty situation using Park transformation and speed estimation method are compared with the results obtained from fast Fourier transforms.

• 한국CDE학회논문집
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• 제8권4호
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• pp.212-221
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• 2003

In order to reduce the lead-time and cost, the technology of rapid prototyping (RP) has been widely used. A new rapid prototyping process, transfer-type variable lamination manufacturing process by using expandable polystyrene foam (VLM-ST), has been developed to reduce building time, apparatus cost and additional post-processing. At the same time, VLM Slicer, the CAD/CAM software for VLM-ST has been developed. In this study, algorithms for accuracy improvement of VLM-ST, which include offset and overrun of a cutting path and generation of a reference shape are developed. Offset algorithm improves cutting accuracy, overrun algorithm enables the VLM-ST process to make a shape of sharp edge and reference shape generation algorithm adds additional shape which makes off-line lamination easier. In addition, proposed algorithms are applied to practical CAD models for verification.

• 한국멀티미디어학회논문지
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• 제19권4호
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• pp.765-773
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• 2016

As multimedia content technology developed, there are many cases that service contents are being provided in many different ways in the cloud-based media service system. A DRM is a technology that can enhance the copyright of the digital content by providing right information. It is available on a single platform and has a problem that the additional cost when the platform is changing. In this paper, we propose a media service system based on cloud computing. It can be used on multiple platforms at the same time by applying a number of DRM for digital contents, and allows use of a new authentication for another platform without any additional cost.

• 한국정보처리학회논문지
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• 제7권4호
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• pp.1073-1081
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• 2000

This paper proposes a new fault-tolerant technique for bitonic sorting networks which can be used for designing ATM switches based on Batcher-Banyan network. The main goal in this paper is to design a cost-effective fault-tolerant bitonic sorting network. In order to recover a fault, additional comparison elements and additional links are used. A Dynamic Redundant Bitonic Sorting (DRBS) network is based on the Dynamic Redundant network and can be constructed with several different variations. The proposed fault-tolerant sorting network offers high fault-tolerance; low time delays; maintenance of cell sequence; simple routing; and regularity and modularity.