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고속회전 하는 정밀부품을 위한 연질/경질 코팅의 트라이볼로지적 특성에 관한 연구
오진규,정구현,김대은,유제환,김형재 한국공작기계학회 2003 한국공작기계학회 춘계학술대회논문집 Vol.2003 No.-
Recently, rotating elements which use mechanical and electrical systems have been utilized for high speed and accuracy to increase the performance. The most important thing to get a more reliable system is to understand the friction, wear and characteristics which has an effect on various coated surfaces. In this study, the tribological characteristics of various soft/hard materials were investigated by using a custom-built pin-on-reciprocator tester. From the experimental results, it was found that the friction coefficients of the soft material coated surfaces were lower under various normal loads due to thier self-lubricating ability and material transfer to the counter surface.
金發鎬,鄭求亨 弘益大學校 科學技術硏究所 2001 科學技術硏究論文集 Vol.12 No.-
The efficient and rational transmission tariff structure is one of the crucial factors in creation of fair and competitive electricity markets. Transmission charge can be largely categorized into the line usage charge, system reliability charge, access charge and others. Any transmission tariff should be able to reflect these cost components reasonably. This paper suggests an approach to allocating the transmission reliability costs. The proposed method is based on the line usage of market participants under normal state. For the allocation of reliability costs, transmission reliability contributions are calculated and these contributions reflect line sensitivity under contingency condition(n-1 line outage state) and line outage rate simultaneously.
Economic Feasibility on the Interconnected Electric Power Systems in North-East Asia
Chung, Koo-Hyung,Kim, Bal-Ho H. The Korean Institute of Electrical Engineers 2007 Journal of Electrical Engineering & Technology Vol.2 No.4
The interstate electric power system, as an alternative for energy cooperation under regional economic block, was fervently debated prior to the restructuring of electric power industries and rapidly expanded in many regions since the 1990s. Especially, electric power system interconnection in the Northeast Asia region may bring considerable economic benefits since this region has strong supplementation in resource holdings, load shape, fuel mix, and etc. In this paper, we implement the ORIRES model, proposed by ESI of Russia, in order to analyze the economic feasibility on the Northeast Asia Region Electrical System Ties (NEAREST) project.
An Analysis on Price Limits of Imported Power via Northeast Asian Power System Ties
Chung, Koo-Hyung,Kim, Balho H. The Korean Institute of Electrical Engineers 2007 Journal of Electrical Engineering & Technology Vol.2 No.3
This paper presents an engineering approach to derive the optimum price levels of transacted power. In this paper, with the assumption that power import is possible through the system connection in Northeast Asia regions, the upper price limit of imported power deserving economic efficiency was derived with respect to the time and amount of power import. The proposed approach was demonstrated based on the data from the National Power Development Planning in 2004 with the WASP model.
An Approach to Optimal Dispatch Scheduling Incorporating Transmission Security Constraints
Koo-Hyung Chung,Dong-Joo Kang,Balho H. Kim,Tai-Hoon Kim,Tae-Kyoo Oh 대한전기학회 2008 Journal of Electrical Engineering & Technology Vol.3 No.2
The introduction of competition in electricity markets emphasizes the importance of sufficient transmission capacities to guarantee effective power transactions. Therefore, for the economic and stable electric power system operation, transmission security constrains should be incorporated into the dispatch scheduling problem. With the intent to solve this problem, we decompose a dispatch scheduling problem into a master problem (MP) and several subproblems (SPs) using Benders decomposition. The MP solves a general optimal power flow (OPF) problem while the SPs inspect the feasibility of OPF solution under respective transmission line contingencies. If a dispatch scheduling solution given by the MP violates transmission security constraints, then additional constraints corresponding to the violations are imposed to the MP. Through this iterative process between the MP and SPs, we derive an optimal dispatch schedule incorporating the post-contingency corrective rescheduling. In addition, we consider interruptible loads as active control variables since the interruptible loads can participate as generators in competitive electricity markets. Numerical examples demonstrate the efficiency of the proposed algorithm.
Chung, Koo-Hyung,Lee, Chan-Joo,Kim, Jin-Ho,Hur, Don,Kim, Balho-H.,Park, Jong-Bae The Korean Institute of Electrical Engineers 2007 Journal of Electrical Engineering & Technology Vol.2 No.1
For electricity markets to function in a truly competitive and efficient manner, it is not enough to focus solely on improving the efficiencies of power supply. To recognize price-responsive load as a reliability resource, the customer must be provided with price signals and an instrument to respond to these signals, preferably automatically. This paper attempts to develop the Windows-based load management system in competitive electricity markets, allowing the user to monitor the current energy consumption or billing information, to analyze the historical data, and to implement the consumption strategy for cost savings with nine possible scenarios adopted. Finally, this modeling framework will serve as a template containing the basic concepts that any load management system should address.
Koo-Hyung Chung,Chan-Joo Lee,Jin-Ho Kim,Don Hur,Blho H. Kim,Jong-Bae Park 대한전기학회 2007 Journal of Electrical Engineering & Technology Vol.2 No.1
For electricity markets to function in a truly competitive and efficient manner, it is not enough to focus solely on improving the efficiencies of power supply. To recognize price-responsive load as a reliability resource, the customer must be provided with price signals and an instrument to respond to these signals, preferably automatically. This paper attempts to develop the Windows-based load management system in competitive electricity markets, allowing the user to monitor the current energy consumption or billing information, to analyze the historical data, and to implement the consumption strategy for cost savings with nine possible scenarios adopted. Finally, this modeling framework will serve as a template containing the basic concepts that any load management system should address.
An Approach to Optimal Dispatch Scheduling Incorporating Transmission Security Constraints
Chung, Koo-Hyung,Kang, Dong-Joo,Kim, Balho H.,Kim, Tai-Hoon,Oh, Tae-Kyoo The Korean Institute of Electrical Engineers 2008 Journal of Electrical Engineering & Technology Vol.3 No.2
The introduction of competition in electricity markets emphasizes the importance of sufficient transmission capacities to guarantee effective power transactions. Therefore, for the economic and stable electric power system operation, transmission security constrains should be incorporated into the dispatch scheduling problem. With the intent to solve this problem, we decompose a dispatch scheduling problem into a master problem(MP) and several subproblems(SPs) using Benders decomposition. The MP solves a general optimal power flow(OPF) problem while the SPs inspect the feasibility of OPF solution under respective transmission line contingencies. If a dispatch scheduling solution given by the MP violates transmission security constraints, then additional constraints corresponding to the violations are imposed to the MP. Through this iterative process between the MP and SPs, we derive an optimal dispatch schedule incorporating the post-contingency corrective rescheduling. In addition, we consider interruptible loads as active control variables since the interruptible loads can participate as generators in competitive electricity markets. Numerical examples demonstrate the efficiency of the proposed algorithm.
An Analysis on Price Limits of Imported Power via Northeast Asian Power System Ties
Koo-Hyung Chung,Balbo H. Kim 대한전기학회 2007 Journal of Electrical Engineering & Technology Vol.2 No.3
This paper presents an engineering approach to derive the optimum price levels of transacted power. In this paper, with the assumption that power import is possible through the system connection in Northeast Asia regions, the upper price limit of imported power deserving economic efficiency was derived with respect to the time and amount of power import. The proposed approach was demonstrated based on the data from the National Power Development Planning in 2004 with the WASP model.