• Proceedings of the KIEE Conference
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• 2001.11b
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• pp.176-178
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• 2001

This paper presents the application draft of ancillary services for Korean Wholesale Electricity Market. This application draft of ancillary services is based on technical rules for ancillary services agreements prepared by KEMA and the present conditions of KEPCO system operations and future directions.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.2
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• pp.256-263
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• 2009

For the power system to keep in a stable operating state, sufficient ancillary services must be available to respond to credible contingency events and return the power system to a satisfactory operating state in the case of contingencies as well as blackout events within specified predefined limits. The logical and reasonable bases of valuing and pricing the ancillary services are required to reach the common ground among market participants. The total amount of black start service transactions is quite small compared to the total ancillary service transactions as well as energy market transactions. Black start services must be provided as one of the ancillary services in the deregulated electricity market. In order to procure and remunerate black start services, it is necessary to quantify the value of the black start sources within the power system. In this paper, an approach to assess the value of the black start service is presented based on the cost-of-service solution. Financial simulation of the influence on market participants for the proposed approach on the service is carried out. The cost of the black start service is allocated in accordance with the principle of "causer pays", and the cost is shared by the producers and consumers equally that created the requirement for the service. Under the present electricity market, the mechanism to recover the cost is not implemented, a new approach to the ancillary services to provide incentive for the service providers has to be studied in the near future.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.41 no.3
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• pp.225-232
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• 2017

Several maintenance issues related to cavitation erosion and fatigue cracks in the water turbine subcomponents of pumped-storage plants, such as a runner and a draft tube, have been reported in the past. Generally, the pumped-storage plants provide ancillary services, such as black-start and system stabilization. The ancillary services are responsible for cyclic low opening operation of the guide vanes. It has been empirically established that this low opening operation further damages the water turbine subcomponents. In this study, the acceleration effect of the low opening operation on the cavitation erosion and fatigue of the water turbine is quantitatively assessed through finite element flow analysis, finite element stress analysis, and fatigue analysis. As a result of the assessment, it is identified that the cavitation potential increases and the turbine efficiency decreases with a decrease in the opening of the guide vane. Also, the low opening operation has an insignificant effect on the fatigue even though it increases the maximum stress values at the runner blade roots.

• Korea Journal of Hospital Management
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• v.10 no.2
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• pp.1-25
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• 2005

This study purports to investigate the determinants of patient satisfaction and intent to revisit at national university hospitals in Korea. A total of 8 independent variables for outpatients, 9 independent variables for inpatients, and an intervening variable of overall patient satisfaction were selected through literature review. The independent variables for outpatients contain the level of satisfaction with physicians, nurses, ancillary staff, administrative procedure, medical cost, physical environment, facility convenience. and health recovery. With regard to the independent variables for inpatients, the quality of ward services was added to those of outpatients. Each variable contains 3 to 8 items measuring the level of satisfaction with various aspects of the variable. The sample used in this study consisted of 879 outpatients and 821 inpatients. Data were collected with interview survey and analyzed using path analysis. The major findings of the study are as follows: 1) The following variables have significantly positive effect on the intent to revisit of outpatients: health recovery, overall satisfaction, satisfaction with physicians, and ancillary staff. 2) The following variables have significantly positive effect on the intent to revisit of inpatients: health recovery, satisfaction with nurses and physicians, overall satisfaction, and administrative procedure. 3) The following variables of admission procedure, satisfaction with ancillary staff, facility convenience, quality of ward services were found to have significantly positive effect only on the level of overall satisfaction, even though they do not have significant total effect on the intent to revisit. The results of the study indicate that national university hospitals in Korea should make an effort to improve the satisfactory level of patients with clinical outcome, services provided by physicians, nurses, and ancillary staff, and the quality of administrative procedure for enhancing the intent to revisit of patients.

• Proceedings of the KIEE Conference
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• 2001.05a
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• pp.187-189
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• 2001

전력산업 구조개편에 따라 개설된 우리나라의 발전경쟁 시장에서 전력계통안정 및 전기품질 확보를 위하여 적용되는 계통운영서비스의 종류와 확보기준 및 운영방법을 소개하고 향후 전력시장의 발전에 따라 적용예정인 계통운영서비스에 대한 운영방향을 검토하였다.

• Journal of Electrical Engineering and Technology
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• v.4 no.3
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• pp.337-345
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• 2009

Deregulation in power industry has made the reactive power ancillary service management a critical task to power system operators from both technical and economic perspectives. Reactive power management in power systems is a complex combinatorial optimization problem involving nonlinear functions with multiple local minima and nonlinear constraints. This paper proposes a practical market-based reactive power ancillary service management scheme to tackle the challenge. In this paper a new model for voltage security and reactive power management is presented. The proposed model minimizes reactive support cost as an economic aspect and insures the voltage security as a technical constraint. For modeling validation study, two optimization algorithm, a genetic algorithm (GA) and particle swarm optimization (PSO) method are used to solve the problem of optimum allocation of reactive power in power systems under open market environment and the results are compared. As a case study, the IEEE-30 bus power system is used. Results show that the algorithm is well competent for optimal allocation of reactive power under practical constraints and price based conditions.

• KIEE International Transactions on Power Engineering
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• v.5A no.4
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• pp.311-321
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• 2005

A competitive generating company (GENCO) could maximize its payoff by optimizing its generation assets. This paper considers the GENCO's arbitrage problem using price-based unit commitment (PBUC). The GENCO could consider arbitrage opportunities in purchases from qualifying facilities (QFs) as well as simultaneous trades with spots markets for energy, ancillary services, emission, and fuel. Given forecasted hourly market prices for each market, the GENCO's generating asset arbitrage problem is formulated as a mixed integer program (MIP) and solved by a branch-and-cut algorithm. A GENCO with 54 thermal and 12 combined-cycle units is considered for analyzing the proposed formulation. The proposed case studies illustrate the significance of simultaneous arbitrage by applying PBUC to multi-commodity markets.

• KDI Journal of Economic Policy
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• v.33 no.2
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• pp.81-110
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• 2011

Credit rating agencies(CRAs) are accused of failing to provide accurate and fair credit ratings and hence being responsible for the crisis. This paper tries to add on to the literature on credit rating reform through examining the CRAs in a model where rating quality is unobservable. We show that unobservability of rating effort results in the sub-optimal level of quality. Then the paper extends the model to incorporate ancillary services, competition and reputation. We show that ancillary services worsen the conflict of interests of the CRAs and that competition and reputation may not be strong enough to discipline the CRAs. Hence regulatory oversight and imposition of liability may be necessary in order to increase the accuracy of ratings.

• ETRI Journal
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• v.37 no.2
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• pp.273-282
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• 2015

Vehicle-to-grid presents a mechanism to meet the key requirements of an electric power system, using electric vehicles (EVs) when they are parked. The most economic ancillary service is that of frequency regulation, which imposes some constraints regarding the period and duration of time the vehicles have to be connected to the grid. The majority of research explores the profitability of the aggregator, while the perspective of the EV fleet owner, in terms of their need for usage of their fleet, remains neglected. In this paper, the optimal allocation of available vehicles on a day-ahead basis using queuing theory and fuzzy multi-criteria methodology has been determined. The proposed methodology is illustrated on the daily scheduling of EVs in an electricity distribution company.

• Journal of the Korea Society of Computer and Information
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• v.23 no.8
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• pp.95-99
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• 2018

This research is related to GPS(global positioning system) enabled device navigation service and consists of two parts. The first is the logic that records the route guidance video and records GPS information in time, and the second is the logic that outputs the created video data based on real time GPS. The recording logic first determines the origin and destination, records the video from the origin to the destination and it adjusts the speed of the image in a specific area so that the user can see it easily. And insert ancillary information and advertisements that can help guide the route. In the output logic, we provide navigation services using the video and GPS data tables we created, and it receives user's GPS information in real time and corrects it based on the recent user location to reduce errors. This provides local guidance services to people who lack language skills like foreigners.