• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 추계학술대회 논문집 전력기술부문
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• pp.67-70
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• 2003

In recent, the importance and necessity of some studies on reliability evaluation of grid come from the recent black-out accidents occurred in the world. The quantity evaluation of transmission system reliability is very important under competitive electricity environment. The reason is that the successful operation of electric power under the deregulated electricity market depends on transmission system reliability management. The various results of many case studies for the IEEE 25buses system using the Transmission Reliability Evaluation for Large-Scale Systems(TRELSS) Version 5_1, a program made in EPRI are introduced in this paper. Some sensitivity analysis has been included. This paper suggests that the some important input parameters of the TRELSS can be determined optimally from this sensitivity analysis for high reliability level operation of a system.

• 전기전자학회논문지
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• 제22권4호
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• pp.1050-1055
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• 2018

In this paper, we analyzed the sensitivity of matching elements for the dual-band operation of a power amplifier with composite right/left-handed (CRLH) transmission lines. Metamaterial theory enables CRLH transmission to support arbitrary impedance matching at dual frequencies. In general, at sub-GHz range, the CRLH matching networks are commonly implemented with lumped elements, which are prone to manufacturing distribution. In order to reduce the effect from the distribution of element values in design, we suggest a method to analyze the sensitivity of matching elements from the performance aspect of power amplifiers. Based on the analysis, a 40dBm dual-band power amplifier operating at 0.7GHz and 1.5GHz is designed.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2002년도 ITC-CSCC -1
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• pp.552-555
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• 2002

Wideband CDMA is one of the radio access technologies for the third generation in which voice is the basic service. There has been lot of research work in order to find out the suitable transmission scheme to meet the requirement of accommodating variable type of services in Wideband-CDMA. This paper studies the behavior of different services using different transmission schemes in Wideband CDU and compares their performance in terms of BER. Different transmission schemes are found to be suitable for different services. Transmission schemes used are- fixed processing gain scheme also called as variable bandwidth scheme, single code transmission and multicode transmission. It is found that fixed processing gain scheme is suitable fur high data rates. Single code transmission is suitable fer low data rates where as multicode transmission is suitable for low and medium data rates.

• 전기학회논문지
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• 제67권3호
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• pp.485-489
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• 2018

Studies have been actively conducted on the magnetic-resonance wireless power transmission (WPT) for commercialization. Such studies are essential for improving the transmission efficiency. In the magnetic-resonance WPT, the inductance (L) and capacitance (C) vary significantly depending on the design of the coils, and the efficiency sharply changes accordingly. To address this problem, studies on the coil design are required. In this study, the S-parameter characteristics according to the number of turns of the coil were analyzed to improve the efficiency of the superconducting WPT. Superconducting coils were designed, and the reflection coefficient ($S_{11}$) according to the turns was analyzed. It was confirmed that the power transmission characteristics were improved as the reactance approached $0{\Omega}$

• 한국전자파학회:학술대회논문집
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• 한국전자파학회 1999년도 제3회 전자장의 생체영향에 관한 워크숍
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• pp.156-164
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• 1999

This paper shows that the configuration of power transmission lines currently in place is suitable on the basis of calculated magnetic field strengths. The magnetic fields were computed for typical current distributions on power transmission lines for electric railways, which are characterized by severe load fluctuations and phase distortions. The result of the numerical analysis are compared with th ELF guidelines of magnetic fields from several case studies. The final conclusion reached in that effects of the magnetic fields near power transmission lines for electric railways are not significant enough to cause a biological safety concern.

• 소음진동
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• 제7권6호
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• pp.945-952
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• 1997

This paper shows the feasibility of the suggestion that the angle distribution of incident sound to panels might be gaussian, instead of the conventional uniform distribution in the analysis of transmission loss of panels. To prove the suggestion, the problems with the diffuse sound field in a reverberation room are examined by case studies and the comparision of the prediction with the measurement of sound transmission loss of walls are performed. The results of the comparision show good agreement between the two values.

• 대한전기학회논문지:전력기술부문A
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• 제54권7호
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• pp.358-365
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• 2005

Transmission networks play an important role which transfer generated electric power to a consumer in power system operation. In a competitive environment of electric power industry, developing the technological criterions and methodologies on transmission planning is becoming new challenge to transmission system planner. The use of a locational signal and the provision of a indicative plan to control the transmission investment reasonably is very important in the viewpoint of a regulator. The main target of this study is to develop a systematic criterion of transmission expansion planning. And system congestion cost is considered. The proposed methodology was demonstrated with several case studies.

• 한국자동차공학회논문집
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• 제5권5호
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• pp.73-85
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• 1997

An automatic transmission is an important element of automotive power systems that allows a driving convenience. Compared to a manual transmission, however, it has a few problems in efficiency, shift feel, and maintenance. To improve these, it is imperative to understand the dynamics of automatic transmissions. This paper develops a dynamically-correct model of an automatic transmission, using the bond graph method. The bond graph method is ideally suited for modeling power systems, because the method is based on generalized power variables. The bond graph method is capable of providing correct dynamic constraints and kinematic constraints, as well as the governing differential equations of motion. The bond graph method is applied to 1-4 in-gear ranges, as well as various upshifts and downshifts of an automatic transmission, which allows an accurate simulation of an automatic transmission. Conventional automatic transmission models have no dynamic constraint, which do not allow correct simulation studies.

• Journal of Electrical Engineering and Technology
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• 제2권2호
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• pp.194-200
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• 2007

The deregulation problem has recently attracted attentions in a competitive electric power market, where the cost must be earmarked fairly and precisely for the customers and the Independent Power Producers (IPPs) as well. Transmission loss is an one of several important factors that determines power transmission cost. Because the cost caused by transmission losses is about $3{\sim}5%$, it is important to allocate transmission losses into each bus in a power system. This paper presents the new algorithm to allocate transmission losses based on an integration method using the loss sensitivity. It provides the buswise incremental transmission losses through the calculation of load ratios considering the transaction strategy of an overall system. The performance of the proposed algorithm is evaluated by the case studies carried out on the WSCC 9-bus and IEEE 14-bus systems.

• 대한기계학회논문집A
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• 제26권10호
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• pp.2194-2200
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• 2002

Transmission error is highly related to gear noise. In order to predict the helical gear noise, transmission error analysis is needed. Up to now, the studies for the transmission error were conducted by the modeling of helical gears only. However, since helical gears are supported by the shaft and bearing, transmission error has the effects of the elements. In this study, the procedure to consider the shaft deformation with bearing stiffness for the transmission error analysis is proposed. To do so, the relationship between gear error and shaft deformation is analytically derived. Shaft deformation with bearing stiffness is analyzed by FEM. It is measured in the experimental test rig by the non-contact displacement sensors. Using the tooth error from tooth modification and the shaft deformation, the effects of shaft on the loaded transmission error are investigated.