• Proceedings of the KIEE Conference
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• 2006.07a
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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.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.54 no.11
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• pp.533-539
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• 2005

According to NERC definition, Available Transfer Capability (ATC) is a measure of the transfer capability remaining in the physical transmission network for the future commercial activity. To calculate Available Transfer Capability, accurate and defensible Total Transfer Capability, Capacity Benefit Margin and Transmission Reliability Margin should be calculated in advance. This paper proposes a method to quantify time varying Available Transfer Capability based on probabilistic approach. The uncertainties of power system and market are considered as complex random variables. Total Transfer Capability is determined by optimization technique such as SQP(Sequential Quadratic Programming). Transmission Reliability Margin with the desired probabilistic margin is calculated based on Probabilistic Load Flow analysis, and Capacity Benefit Margin is evaluated using LOLE of the system. Suggested Available Transfer Capability quantification method is verified using IEEE RTS with 72 bus. The proposed method shows efficiency and flexibility for the quantification of Available Transfer Capability.

• KIEE International Transactions on Power Engineering
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• v.5A no.2
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• pp.152-158
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• 2005

This paper describes a reactive optimal power flow incorporating margin enhancement constraints. Margin sensitivity at a steady-state voltage instability point is calculated using invariant space parametric sensitivity, and it can provide valuable information for selection of effective control parameters. However, the weakest buses in neighboring regions have high margin sensitivities within a certain range. Hence, the control determination using only the sensitivity information might cause violation of operational limits of the base operating point, at which the control is applied to enhance voltage stability margin in the direction of parameter increase. This paper applies an interior point method (IPM) to solve the optimal power flow formulation with the margin enhancement constraints, and shunt capacitances are mainly considered as control variables. In addition, nonlinearity of margin enhancement with respect to control of shunt capacitance is considered for speed-up control determination in the numerical example using the IEEE 118-bus test system.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.54.3-54
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• 2001

This paper presents a controller design technique for standard 2nd-order system satisfying user-specified phase margin. A simple method is presented to meet stability margin for the 2nd-order system, which is important since the 2nd-order plant models are frequently encountered in the practical plant models such as actuators of the optical drive systems. Through the comparison of the specified stability margin and achieved stability margin, it is shown in the simple example that the proposed technique is useful in the initial design of control systems with stability margin specifications.

• Journal of Mechanical Science and Technology
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• v.20 no.11
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• pp.1934-1941
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• 2006

As the operating time of heat exchangers progresses, fouling caused by water-borne deposits and the number of plugged tubes increase and thermal performance decreases. Both fouling and tube plugging are known to interfere with normal flow characteristics and to reduce thermal efficiencies of heat exchangers. The heat exchangers of Korean nuclear power plants have been analyzed in terms of heat transfer rate and overall heat transfer coefficient as a means of heat exchanger management. Except for fouling resulting from the operation of heat exchangers, all the tubes of heat exchangers have been replaced when the number of plugged tubes exceeded the plugging criteria based on design performance sheet. This paper describes a plugging margin evaluation method taking into account the fouling of shell-and-tube heat exchangers. The method can evaluate thermal performance, estimate future fouling variation, and consider current fouling level in the calculation of plugging margin. To identify the effectiveness of the developed method, fouling and plugging margin evaluations were performed at a component cooling heat exchanger in a Korean nuclear power plant.

• Proceedings of the KIEE Conference
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• 2007.04a
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• pp.113-118
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• 2007

In this paper, a new method is proposed for robust proportional- integral - derivative (PID) control that is to ensure specified phase margin and iso - damping property using reduction model. This method is based on the second order plus dead time(SOPDT) reduction model of the high order model. Reduction model used to ensure iso-damping property in the feature frequency. Simulation results gives proof of effectiveness of proposed method.

• International Journal of Internet, Broadcasting and Communication
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• v.13 no.2
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• pp.187-194
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• 2021

This paper presents a margin-based face liveness detection method with behavioral confirmation to prevent spoofing attacks using deep learning techniques. The proposed method provides a possibility to prevent biometric person authentication systems from replay and printed spoofing attacks. For this work, a set of real face images and fake face images was collected and a face liveness detection model is trained on the constructed dataset. Traditional face liveness detection methods exploit the face image covering only the face regions of the human head image. However, outside of this region of interest (ROI) might include useful features such as phone edges and fingers. The proposed face liveness detection method was experimentally tested on the author's own dataset. Collected databases are trained and experimental results show that the trained model distinguishes real face images and fake images correctly.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.48 no.4
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• pp.351-357
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• 1999

This paper proposes the coordinated control of SVC and UTLC at the distribution substation to get larger operating margin of SVC for the voltage stability control by reactive power compensation. In the conventional method, ULTC doesn't respond to the variation of source voltage, so SVC has the entire responsibility for it. It could cause the lack of operating margin of SVC in some condition. It, however, is important to secure an operating margin for the dynamic stability control in emergancy. This paper proposes the coordinated control method that SVC controls the supply voltage and ULTC respond to the SVC compensation valve based on the relation between SVC compensation and ULTC tap position. The numerical simulation verifies that the proposed system could increase the operating margin of SVC compared with the conventional system.

• Earthquakes and Structures
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• v.12 no.6
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• pp.653-663
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• 2017

A seismic margin assessment evaluates how much margin exists for the system under beyond design basis earthquake events. Specifically, the seismic margin for the entire system is evaluated by utilizing a systems analysis based on the sub-system and component seismic fragility data. Each seismic fragility curve is obtained by using empirical, experimental, and/or numerical simulation data. The systems analysis is generally performed by employing a fault tree analysis. However, the current practice has clear limitations in that it cannot deal with the uncertainties of basic components and accommodate the newly observed data. Therefore, in this paper, we present a Bayesian-based seismic margin assessment that is conducted using seismic fragility data and fault tree analysis including Bayesian inference. This proposed approach is first applied to the pooltype nuclear research reactor system for the quantitative evaluation of the seismic margin. The results show that the applied approach can allow updating by considering the newly available data/information at any level of the fault tree, and can identify critical scenarios modified due to new information. Also, given the seismic hazard information, this approach is further extended to the real-time risk evaluation. Thus, the proposed approach can finally be expected to solve the fundamental restrictions of the current method.

• THE INTERNATIONAL COMMERCE & LAW REVIEW
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• v.38
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• pp.265-302
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• 2008

This paper intends to analyse some legal issues on "Zeroing" which is based on the article 2.4.2 under the WTO Anti-dumping Agreement. "Zeroing" stands for a specific methodology in calculating a general dumping margin for a product in question under which negative individual dumping margins are treated as zero (thus "zeroed") before aggregating all individual dumping margins. The article 2.4.2 of the Anti-dumping Agreement regulates three types of calculating methodology on dumping margin as first symmetrical method(average-to-average: A-A), second symmetrical method(individual-to-individual: I-I) and asymmetrical method(average-to-individual: A-I). However, this article does not have any provisions about the "Zeroing" practice. In their anti-dumping practices, the EC and the United-States calculated dumping margin based on the "Zeroing", but this methodology has been disputed in the Dispute Settlement Body(DSB) of the WTO. This paper analysed their legal problems with some WTO cases in particular concerning EC-Bed Linen, U.S.-Softwood Lumber Zeroing, U.S.-Zeroing(EC) and U.S.-Sunset Review(Japan) cases. On the basis of theses analysis, we can therefore ask some questions as follows; To begin with, although the article 2.4.2 of the WTO Anti-dumping Agreement does not clearly refer to the "Zeroing", how do some developing countries, as the U.S.A and the E.U. calculate dumping margin as the "Zeroing"? Secondly, what is the relationship between the symmetrical method and asymmetrical method to the dumping margin? And if we adopt the zeroing method, what is the different rate to anti-dumping margin? Thirdly, although the Panel decided that the zeroing methodology of dumping margin used by th U.S.A in administrative review between the U.S.A and the E.U, why does the Appellate Body made the decision that the american methodology is incompatible with the WTO Anti-dumping Agreement? Lastly, what will be affected the upper decision taken by the Appellate Body to the DDA negotiation of anti-dumping matters? Even though the WTO Appellate made a decision that the zeroing method is incompatible with the principles of the WTO law, this methodology contains a lot of problems. Some members of the WTO as the U.S.A and the E.U did not officially declare this methodology to abandon, and the debate concerned is arguing. Therefore this paper tried to present the adequate solution in order to promote the zeroing methodology in the international anti-dumping system and practices.