• 한국전자거래학회지
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• 제7권2호
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• pp.55-68
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• 2002

Internet group buying systems have been widely used recently. In those systems, because the reserve price is provided by the buyer, the success rate can be decreased if the reserve price is set too low compared with the normal price. Otherwise, an unsuitable successful bid can be made if the reserve price is set too high based on inaccurate information. Likewise, the seller's providing too high a bid price can deteriorate his/her own successful bid rate, whereas a successful bid with too low a price may make no profit in the sale. Therefore, pricing agents that recommend adequate prices based on the past buying and selling history data can be helpful. In this paper, we propose two kinds of agents. One suggests reserve prices to buyers based on the past buying history database of the system. The other recommends bid prices to a seller based on the past bidding history data of the company using the cost accounting theory. Through performance experiments, we show that the successful bid rate can increase by preventing buyers from making unreasonable reserve prices. Also, we show that, for the seller, the rate of successful bids with appropriate profits can increase. Using the pricing agents, we design and implement an XML-based group buying system.

• 대한전기학회논문지:전력기술부문A
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• 제55권5호
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• pp.202-213
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• 2006

This paper presents a new approach for optimal dispatch of energy and frequency regulation reserve considering contingency in a competitive electricity market. It is necessary to introduce the reserve market with the spot energy market for operating efficiently and obtaining the security of the electricity market. However, the reserve market is closely connected with the energy market since the energy and reserve are produced from the same resources. Thus, it is inevitable to co-optimize the energy and ancillary service for efficient operation of energy and ancillary service market. Therefore, this paper proposes a new method for optimal dispatch of energy and frequency regulation reserve considering n-1 contingency of generator and transmission line using constraints and sensitivity based on AC power flow To verify the effectiveness of the proposed method, the numerical studies have been performed for 5-bus sample system and modified IEEE 14-bus system.

• 대한핵의학회지
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• 제32권4호
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• pp.314-324
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• 1998

목적: 이 연구의 목적은 어린이 모야모야병 환자에서 휴식기/아세타졸아미드 부하 Tc-99m-HMPAO SPECT가 Encephalo-duro-arterio-synangiosis (EDAS) 수술 후의 호전여부를 평가할 수 있는지를 알아보고자 함이었다. 대상 및 방법: 어린이 모야모야병 18명에서 21개의 대뇌반구에 EDAS 수술을 하였다. 수술 전과 수술 후 3개월에 휴식기/아세타졸아미드 부하 Tc-99in-HMPAO SPECT를 시행하여 휴식기관류와 관류예비능을 평가하여 비교하였다. 결과: 대뇌반구 모두에서 휴식기관류 또는 관류예비능 감소가 관찰되었다. 84개 뇌엽과 294개 영역 중52%의 뇌엽과 50%의 영역에 관류이상이 나타났다. 수술 후 휴식기 관류 또는 관류예비능이 감소한 영역의 60%가 호전되었고 반구는 71%가 호전되었다. 수술 전 휴식기 관류 감소가 심하지 않았을 때 수술후 호전가능성이 높았다. 수술 전 휴식 부하기 관류의 차이가 있는 경우 즉 관류예비능이 감소하였을 때 수술 후 관류 호전 가능성이 높았다. 결론: 어린이 모야모야병에서 수술 전 휴식기/아세타졸아미드 Tc-99m-HMPAO SPECT로 수술 후 호전여부를 예측할 수 있다.

• Journal of Forest and Environmental Science
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• 제27권2호
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• pp.93-99
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• 2011

In this study, a total of 350 households contained 700 individuals in Iganzo village were surveyed to study their literate and poverty levels and their impacts to conservation of the Mbeya Range Forest Reserve. The study included 350 women and 350 men. The majority of respondents were between the ages of 31-40 years old (53%), while the rest were between 41-50 years old (25%) and 21-30 years old (22%). The total income per day per household was calculated and averaged to 4,570 Tanzanian shillings that is equal to about 3 U.S. dollars. The average number of members per household was seven. It was reported that, there is a tremendous decrease in biodiversity composition of the reserve mainly due to poverty (80%) and ignorance (76%) of the people on the importance of the reserve. Other causes for this decrease were reported to be grazing of livestock in the reserve (23%), poor farming systems (68%), which resulted in soil erosion, encroachment (64%) through expansion of farms towards the reserve boundary and charcoal burning (34%). Respondents from Mbeya Urban Water Supply Authority and District Forest Office mentioned lack of funds (49%) and lack of experts (56%) as challenges that face the conservation of the reserve. It was revealed that 25% of respondents had never gone to school, 53% had primary level of education as their highest level of education, 20% had secondary education and 2% had first degree. The null hypothesis that poverty and illiteracy have a positive correlation to forest degradation was accepted based on these findings at a probability of p>0.85. Thus, it was concluded that poverty and illiteracy among Iganzo village residents are the main causes for the degradation of biodiversity in Mbeya Range Forest Reserve.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 제36회 하계학술대회 논문집 A
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• pp.751-753
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• 2005

In this raper, Economic value of reserve margin i.i presented by opportunity cost for Korean power system, and the level of compensation for spinning reserve that is necessary to operate power system stably is proposed. The generator that is giving up for opportunity to participate in energy market must take opportunity cost. it is relative to not only whole demand level but also marginal cost of each resource. In this paper, assume that all resource in Korea is equivalent to six generator for simulation. and we evaluate value of reserve in the time of high demand and low demand. Also we propose the way to improve a evaluation method by examine relationship between capacity payment and value of reserve.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 제37회 하계학술대회 논문집 A
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• pp.418-419
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• 2006

After electricity power industry restructuring, "Long term power development plan", setting up by government, is replaced by "Basic plan of electricity supply and demand". In this basic plan, one of the most important factors is assessment of appropriate capacity margin. The benefit of GENCO is decided by the market price, and the price is largely affected by the level of reserve margin. As a consequence, appropriate reserve margin is determined by market power. However, Cost Based Pool(CBP) is a limited competitive market, and government policy for supply and demand is very important factor or reserve margin determination. This paper points out issues about existing reserve margin assessment method which is used in basic plan and suggests improved assessment method. In the case study, capacity margin is calculated by proposed assessment method and result shows the advantages of suggested method.

• 전기의세계
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• 제24권5호
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• pp.97-102
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• 1975

This paper describes the result of a Study for the Optimum Operating method with Spinning reserve in case of outage of large generator unit to improve the system stability and prevent the system frequency drop. This is usually done by governor free operation, so we focused our attention to the operating Char acteristics of spinning reserve. Nexy, a study was made to mesure the upper limit of Spinning reserve and when this upper limit cannot match the required power, a relationship between the amount of spinning reserve and that of the load shedding requirement was searched with regard to several system operating conditions to use it in our future system operation. By this study, the optimum system operating method was recommended for reliable operation of power system.

• 전기학회논문지
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• 제56권11호
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• pp.1892-1902
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• 2007

This paper presents a new generating unit maintenance scheduling algorithm considering regional reserve margin and transfer capability. Existing researches focused on reliability of the overall power systems have some problems that adequate reliability criteria cannot be guaranteed in supply shortage regions. Therefore specific constraints which can treat regional reserve ratio have to be added to conventional approaches. The objective function considered in this paper is the variance (second-order momentum) of operating reserve margin to levelize reliability during a planning horizon. This paper focuses on significances of considering regional reliability criteria and an advanced hybrid optimization method based on PSO algorithm. The proposed method has been applied to IEEE reliability test system(1996) with 32-generators and a real-world large scale power system with 291 generators. The results are compared with those of the classical central maintenance scheduling approaches and conventional PSO algorithm to verify the effectiveness of the algorithm proposed in this paper.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1995년도 하계학술대회 논문집 B
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• pp.581-583
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• 1995

This paper presents a theory on the pricing and allocation of spinning reserve. It is shown in this paper, that it is possible to maintain system security with many participants each attempting to optimize their own benefit, through pricing incentive. Participant offers power consumption/generation and reserve contribution according to its price. And Price setter only distribute pricing signal to acquire system security. Participants induce disturbance on power system and they pay the penalty according to the size of disturbance. And they also offers some reserve capacity to earn reserve cost. In this scheme, the amount of data communication is very small.

• 전기학회논문지
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• 제66권1호
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• pp.1-6
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• 2017

Total capacity of pumped hydro storage(PHS) in Korean power system reaches 4,700MW, though the share of it is about 4.56% of total capacity The Unit Commitment program, E-terracommit which is used for the operational purpose by KPX, includes the PHS model. But the model has a defect that it does not include the information of water level of upper reservoir. Therefore two types of improved the PHS models are represented in this paper. The first model is a optimized model by connecting the upper reservoir water level to the non-spinning reserve. The other model is to have priority allocate both the PHS and combined cycle generator for non-spinning reserve. The proposed two models and the E-terracommit model is compared and resulting to have improvement in estimating non-spinning reserve when using the proposed models.