• Journal of the Korea Convergence Society
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• v.10 no.6
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• pp.203-218
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• 2019

Using the sample of 104 mutual savings banks inspected by the Financial Supervisory Service (FSS) on June 2011, this study examines if mutual savings banks manage BIS capital adequacy ratio using allowance for bad debts through comparison of BIS capital adequacy ratio before and after the 2011 when mutual savings banks experienced a large-scale restructuring by financial supervisory authorities. We find that mutual savings banks mainly use the allowance for bad debts to manage BIS capital adequacy ratio. It also shows that mutual savings banks with a business suspension order by FSS manage BIS capital adequacy ratio more than the others. Lastly, we find that Non Big4 auditors as well as Big 4 auditors don't effectively audit the use of the allowance for bad debts for mutual savings banks to manage their BIS capital adequacy ratio.

• Journal of the Korean Institute of Intelligent Systems
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• v.7 no.2
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• pp.52-65
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• 1997

This paper presents a design technique of self tuning fuzzy controller for load frequency control of power system. The proposed parameter self tuning algorithm of fuzzy controller is based on the gradient method using four direction vectors which make error between inference values of fuzzy controller and output values of the specially selected optimal controller reduce steepestly. Using input-output data pair obtained from optimal controller, the parameters in antecedent part and in consequent part of fuzzy inference rules are learned and tuned automatically using the proposed gradient method. The related simulation results show that the proposed fuzzy controller is more powerful than the conventional ones for reductions of undershoot and steady-state load frequency deviation and for minimization of settling time.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.23 no.2
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• pp.175-181
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• 2009

In this paper, it is suggested that the selection method of parameter of Power System Stabilizer(PSS) with robustness in low frequency oscillation for Static VAR Compensator(SVC) using a self tuning fuzzy controller for a synchronous generator excitation and SVC system. The proposed parameter self tuning algorithm of fuzzy controller is based on the steepest decent method using two direction vectors which make error between inference values of fuzzy controller and output values of the specially selected PSS reduce steepestly. Using input-output data pair obtained from PSS, the parameters in antecedent part and in consequent part of fuzzy inference rules are learned and tuned automatically using the proposed steepest decent method.

• Proceedings of the Korean Magnestics Society Conference
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• 1993.11a
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• pp.76-77
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• 1993

• 전기의세계
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• v.25 no.4
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• pp.12-16
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• 1976

Thyristor등의 반도체등의 전자장치를 사용하여 전력의 변환, 제어 및 개폐등을 행하는 기술분야를 1962년 Storm씨가 Solidstate Power Electronics라고 부르기 시작한 이래 급속한 발전을 이룩하여 왔음은 다 아는 사실이다. Storm씨는 1950년대에 전력제어를 위한 장치로써 가포화 리액터를 이용한 자기증폭기의 개발과 이론전개에 공헌한 분으로 전력용 반도체 소자의 개발의 필요성과 그 응용면의 가치를 가장 절실히 느끼고 있었다. 이는 자기증폭기가 무접점의 자기적 switch가 기계적인 switch에 비하여 응답속도가 빠른 것은 사실이나 400Hz 이상에서는 그 한계성을 가져왔기 때문에 새로운 소자 즉 전자적 전력 switch의 개발의 필요성을 당연하였던 것이다. 이상과 같은 소자들은 동작면에서 전압의 증폭을 대상으로 한것이 아니고 전류의 단속에 의한 전력변환을 목적으로 한 것이라고 볼 수 있다. 즉, 단위전하의 에너지로 표시되는 전압의 조정이 아니고 전하의 수를 조정하는 전류조정작용을 가지 소자라는 점에서 이들을 이용한 장치는 전류제어형이어야만 할 것이다.

• Proceedings of the Korean Magnestics Society Conference
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• 1991.05a
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• pp.65-66
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• 1991

• Proceedings of the Korean Magnestics Society Conference
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• 1991.11a
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• pp.30-31
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• 1991

• Proceedings of the Korean Magnestics Society Conference
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• 1992.10a
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• pp.54-55
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• 1992

• Environmental and Resource Economics Review
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• v.24 no.3
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• pp.523-549
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• 2015

This paper investigates an oil refiner's asymmetric behavior in the adjustments of gasoline and diesel prices to changes in his own price and his rivals' prices as well as input costs. An asymmetric error correction model which allows a firm's pricing behavior to the deviation of other firms' prices from their long-run equilibrium level is employed for estimation using weekly data for the period April 2009 to January 2015. Evidence is found that there is a significant degree of asymmetry in the adjustment of wholesale prices to changes in crude oil price. A similar result in regard to the exchange rate is also found by the data. The estimation results for firm's response to changes in other firms' prices indicates that implicit collusion could be more easily exploited in the wholesale petroleum market as results of firms' interaction with each other and anticipation of rivals' pricing behavior. A few refiners show competitive price adjustment in response to the upward deviation of the others' prices from their equilibrium level.

• The Bulletin of The Korean Astronomical Society
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• v.38 no.1
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• pp.41.1-41.1
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• 2013

우주 자기장의 기원은 잘 알려져 있지 않다. 크게 나누어서 우주론적인 기원과 천문학적인 기원을 고려할 수 있다. 자기장의 기원이 무엇이든지 간에, 난류는 씨앗자기장을 증폭시키는데 큰 역할을 한다. 본 발표에서는 천문학적인 기원을 가지는 씨앗자기장이 난류 내에서 어떻게 성장하는 지를 논의한다. 또한 과연 관측을 통해서 천문학적 기원과 우주론적 기원을 구분할 수 있는 지를 논의한다.