• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.45 no.5
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• pp.386-392
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• 2017

This paper considers the analysis of the flight performance reserve, which is required propellant to compensate various launch vehicle performance deviations, to inject the payload of a 3-staged launch vehicle to a circular sun synchronous orbit at a height of 700 km. The various error sources, which affect the orbit injection accuracy, and their uncertainty are defined first. Then the sensitivity analysis, which has the advantage that each error source effect can be investigated independently, is performed for the extreme ${\pm}3{\sigma}$ conditions of the launch vehicle performance errors. Monte carlo simulations are also conducted to compute the propellant reserve, which can consider the combined effects of each error source. Finally the obtained flight performance reserves by the two approaches are compared and it is confirmed that they show similar results.

• Proceedings of the KIEE Conference
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• 2005.07a
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• pp.298-300
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• 2005

전력계통의 주파수조정예비력(Frequency Regulation Control)은 부하 변동에 대응하여 규정된 주파수를 유지하고 안정된 전력계통 운영이 가능하도록 단시간 내에 응동할 수 있는 예비력이다. 본 논문은 우리나라 전력계통에 적합한 위와 같은 주파수조정예비력을 제시하고 전력산업 구조개편에 따라 분리된 발전사업자들이 전력시장에서 대부분의 주파수조정예비력을 담당하는 화력발전소 예비력 확보 방안을 연구 검토한 것이다.

• Proceedings of the KIEE Conference
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• 1999.11b
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• pp.203-205
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• 1999

The unit commitment is an important problem of production scheduling which determines the generating unit to in service(on/off) during scheduling period, to meet system demand and reserve requirement at minimum cost. This paper presents an box type crossover to improve searching ability of GA, to solve unit commitment problem. Satisfactory results are obtained by GA with the proposed crossover operator.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.103-104
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• 2008

This paper proposes an alternative methodology for deciding an optimum deterministic reliability level (IRR; Installed Reserve Rate) by using probabilistic reliability criterion (LOLE; Loss of Load Expectation). Additionally, case studies using the proposed method induce the characteristics of relationship between the probabilistic reliability index (LOLE) and deterministic reliability index (IRR) for 2008 year in Korea power system. The case study presents a possibility that an optimum IRR level in Korea can be assessed using the proposed method. Korea power system has been using the LOLE criterion to determine the adequacy of installed capacity (ICAP) requirement. The criterion in Korea is that the loss of load expectation shall not exceed the available capacity more than five day in ten years (=0.5[days/year]). The probabilistic reliability evaluation and production cost simulation program which is called PRASim is used in order to evaluate the relationship and optimum IRR in this paper.

• Journal of the Korea institute for structural maintenance and inspection
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• v.12 no.1
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• pp.183-192
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• 2008

Generally, application of steel pipe pile as deep foundation member needs special requirement for the connection method between steel pipe pile and concrete footing. Even though two types of connection method are suggested in the korea highway bridge code, type-B method is prevalent. In this study, vertical, lateral, and tension loading test are done for two types of type B connection to review stress concentration, formation and behavior of imaginary RC column in the footing. Welding type and hook type as the connection method are considered in this study. Test results show that welding type have the more reserve capacity than hook type and the specimens connected by the welding type behave as the imaginary RC column in the footing. However, the specimens connected by the hook type did not behave as the imaginary RC column in the footing but behave as the hinge.

• Korean Management Science Review
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• v.30 no.1
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• pp.125-137
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• 2013

The U.S. Army is capable and ready to deploy full-spectrum armed forces anywhere in the world as we have seen in Iraq and Afghanistan. This commitment is within the realm of logistics support that the readiness to support MRE(Meal Ready to Eat), according to the environment where the operation is on going. ROKA(Republic Of Korea Army) proceeds with the program to develop and reserve various MRE under the assumption of distinctive warfare operating environment. This study investigates to determine the amount of MRE consumption within various operating environment and details are as follows. First we ponder the concept of MRE and identified problems of the existing program. Second we also establish feeding rations by the types of MRE that is the base for calculation. Third we introduce MRE consumption algorithm and formula. Fourth and last we have applied our model to the program and analyzed the results. The present state of the estimation didn't reflect various warfare operating environment. Therefore we simulates theater wargame model to determine the consumption under various warfare operating environment. The result of this study is anticipated to contribute largely to the force enhancement as it mirrors of every circumstances of operating environment.

• Proceedings of the KIEE Conference
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• 2008.11a
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• pp.309-311
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• 2008

This paper introduces the characteristics of relationship between probabilistic reliability (LOLE; Loss of Load Expectation) and deterministic reliability (SRR; supply reserve rate) for 2008 year in Korea power system. Korea power system has been using the LOLE criterion to determine the adequacy of installed capacity (ICAP) requirement. The criterion is that load shall not exceed the avaliable capacity, on the average, more than five day in ten years. The probabilistic reliability evaluation and production cost simulation program which is called PPHFHT was used in order to obtain the relationship in this paper.

• Proceedings of the KIEE Conference
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• summer
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• pp.740-742
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• 2004

In TWBP markets, ISO determines the maintenance schedule based on Gencos' and Transcos' offers under reasonable criterion. This paper presents ISO's alternative procedure to coordinate maintenance schedules submitted by Gencos and Transcos. ISO's coordination procedure is formulated as an optimization problem that minimizes expected losses in Gencos' revenue subject to system reserve requirement.

• KDI Journal of Economic Policy
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• v.36 no.3
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• pp.61-93
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• 2014

This paper analyzes Onbid car auction data by employing various methods, including structural estimation, to identify main factors which decides auction prices and figure out what effects those factors are making on the auction price. I then discuss on how to maximize sellers' revenue in OnBid car auctions. The government and public institutes sell their assets through the OnBid auction, hence the optimal design of the OnBid auction is important. The paper's main findings are as follows: (ⅰ) The independent private value model explains OnBid car auction data better than the correlated private value model or the interdependent value model; (ⅱ) Both the number of bidders and the ratios of the auction price to the evaluation value were lower in the auctions posted by the Kamco than auctions by institutes other than the Kamco; (ⅲ) Some auctions require that at least two bidders should submit a bid no less than the reserve price for sale. In those auctions, both the number of bidders and each bidder's valuation on the auctioned object were lower than in auctions without that requirement; (ⅳ) The sum of sellers' revenue would be decreased in the simulation with the reserve price higher by 5%, 10%, and 20% across auctions by institutes other than Kamco.

• THE INTERNATIONAL COMMERCE & LAW REVIEW
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• v.17
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• pp.93-125
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• 2002

This paper aims to find a reasonable solvency margin system in non-life insurance industry and also to evaluate the appropriateness of the current solvency margin regulation system in Korea. The current solvency margin system in Korea, based on EU's solvency margin model, was introduced during the 1997 financial crisis. The solvency requirement is not based on non-life insurer's risk, but simply on written premiums. The current solvency margin for general insurance, such as fire, marine, and automobile insurance, is determined by the greater between a premium-based amount and a claim-based amount, where the premium-based solvency margin is calculated by multiplying the net written premium for the preceding year by the premium based solvency margin ratio. Also, the amount of solvency margin for long term insurance is set at 4% of the policy reserve of the long term insurance. Still, there exist many differences between the current solvency margin regulation system in Korea and EU's model. This paper focuses on the rationality of the solvency margin regulation system, and compares the current system in Korea with EU's model and the RBC(Risk Based Capital) system in U.S. and Japan. Finally, this paper suggests a more specific and reasonable solvency margin system to be developed in Korea.