• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.27 no.1
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• pp.68-75
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• 2013

This paper presents a scheme to improve transient stability using Newton's Approach for generation rescheduling. For a given contingency, the energy margin and sensitivities are computed. The bigger energy margin sensitivity of generator is, the more the generation of the generator effects to the transient stability. According to energy margin sensitivity, the control variables of generation rescheduling are selected. The fuel cost function is used as objective function to reallocate power generation. The results are compared to the results of time simulation to show its the effectiveness.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.51 no.11
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• pp.541-545
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• 2002

This paper proposes the new narrow erase method to erase wall charges formed in an AC plasma display panel (PDP) cell. In the proposed method, pulse timing of switch at the sustain period is adjusted for inducing, a weak discharge. Then, after the narrow erase, the voltage of the X electrode is set to differ from that of the Y electrode. For the proposed method, the measured maximum address voltage margin was 38.3V at Y_Rest voltage of 100V and sustain voltage of 180${\sim}$185V. However, for the conventional method, in which the X and Y electrodes are set to be of equal voltage after the narrow erase, the measured maximum address voltage margin was 31.3V at Y_Rest voltage of 150V and sustain voltage of 180V. This result shows that the measured maximum voltage margin for the proposed method is about 7V(22%) higher than that for the conventional method.

• Journal of the Korean Society of Industry Convergence
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• v.8 no.2
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• pp.85-95
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• 2005

The margin level in the futures market platys an important role in balancing the default probability with the investor's opportunity cost. In this paper, we investigate whether the movement of KOSPI200 futures daily prices can be modeled with the extreme value theory. Based on this investigation, we examine the validity of the margin level set by the extreme value theory. Moreover, we propose an expected profit-maximization model for securities companies. In this model, the extreme value theory is used for cost estimation, and a regression analysis is used for revenue calculation. Computational results are presented to compare the extreme value distribution with the empirical distribution of margin violation in KOSPI200 and to examine the suitability of the expected profit-maximization model.

• 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.

• Journal of Korean Dental Science
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• v.1 no.1
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• pp.22-27
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• 2008

Purpose : This study sought to evaluate the dimensional stability of the SITT (Silicone Index Tooth Tray) impression system and to determine whether providing space for wash impression material in SITT is a necessary step in obtaining accurate prostheses. Materials and methods : After mounting metal dies with shoulder and chamfer margins arbitrarily, SITT was fabricated using Blu-mousse$^{(R)}$. To test the dimensional stability of the SITT system for margin design, the shoulder margin and chamfer margin were evaluated. Furthermore, to test the effect of space for wash impression material, 0.5mm space in SITT and zero space in SITT were statistically compared. Results : 1. There was no significant difference between the group with shoulder margin and that with chamfer margin. 2. There was no significant difference between the group with 0.5mm space and that with zero space for wash impression material. Conclusions : Considering the limitations of this study, the dimensional stability of the SITT system did not interfere with the margin design. Space for the wash impression material was also unnecessary.

• The Journal of the Korean dental association
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• v.19 no.6 s.145
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• pp.489-490
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• 1981

• Journal of Technologic Dentistry
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• v.13 no.1
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• pp.5-8
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• 1991

There are many factors influence on the margin fitness of Casting body. Among them, I intend to examine the influence of the gap of temperature of investment's special liguid. As the result of investing and experiment of the whole of eighty copings under the classification the temperature of liquid into four groups 0$^{\circ}C$, 10$^{\circ}C$, 20$^{\circ}C$, 30$^{\circ}C$ I came to the conclusion as following. 1. The margin fitness of these four groups, as the result of examination with microscope, was the most accurate at 20$^{\circ}C$ was less aceurate in order of 30$^{\circ}C$, 10$^{\circ}C$, 0$^{\circ}C$. 2. directions is the way to preserve the most exact margin fitness.

• Restorative Dentistry and Endodontics
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• v.15 no.2
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• pp.122-126
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• 1990

To examine the microleakage of posterior esthetic restorative materials, using 2% methylene blue dye solution, dye penetration was determined with 80 permanent posterior teeth after thermocycling. The following results were obtained. 1. Amalgam group showed the most severe dye penetration of all test groups through the enamel and dentin / cementum margins. 2. Clearfil group showed much more dye penetration than P-50 at the enamel margin and than resin inlay system at the dentin / cementum margin. 3. Through the etched enamel margin, P-50 and resin inlay system groups showed no dye penetration, if any, but through the dentin / cementum margin, all test groups showed dye penetration. 4. Resin inlay system showed the least dye penetration of all test groups through the dentin / cementum margin.

• KIEE International Transactions on Power Engineering
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• v.4A no.3
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• pp.141-145
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• 2004

FACTS devices, such as the Thyristor Controlled Series Compensator (TCSC) and Static Var Compensators (SVC), can help increase system load margin to improve static voltage stability. In power systems, because of the high cost and the effect value, the optimal placement for FACTS devices must be determined. This paper investigates the use of the series device (SVC) and the parallel device (TCSC) from the point of load margin to increase voltage stability. It considers the sensitivity of load margin to the line reactance and eigenvector of the collapse. The study has been carried out on the IEEE 14 Bus Test System to verify the validity and efficiency of the method. It reveals that incorporation of FACTS devices significantly enhance load margin as well as system stability.

• 한국연소학회:학술대회논문집
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• 2013.06a
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• pp.117-119
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• 2013

Combustion stability margin of a model gas turbine has been assessed by utilizing damping ratios of measured dynamic pressure data. It is known that acoustic oscillations in combustion chambers can be described as a superposition of nonlinearly interacting oscillators. Based on this theoretical background, CSMA (Combustion Stability Margin Assessment) code has been developed. The code has been employed into a model gas turbine combustion experiment, focused on the combustion instability, to show its capability to determine the damping ratio of measured dynamic pressure and further to assess combustion stability margin of the experiment, and turned out that the code works well.