• Journal of the Korean Data and Information Science Society
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• 제14권3호
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• pp.687-696
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• 2003

This article presents a new family of the estimating functions related with minimum distance estimations, and discusses its relationship to the family of the minimum density power divergence estimating equations. Two representative minimum distance estimations; the minimum $L_2$ distance estimation and the minimum Hellinger distance estimation are studied in the light of the theory of estimating equations. Despite of the desirable properties of minimum distance estimations, they are not widely used by general researchers, because theories related with them are complex and are hard to be computationally implemented in real problems. Hopefully, this article would be a help for understanding the minimum distance estimations better.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 하계학술대회 논문집 A
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• pp.12-15
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• 2002

Korea Power System Protection Setting Rule was used from the rectify 1990's. Thereafter transmission voltage is raised the voltage into 765kV, and introduction to new technology of Power System, and was many of variation but, it is using. The present is using Digital type distance relay for 765kV transmission line protection. If impedance value of transmission line were to value lower than setting, this would be operating and relay setting rule is for 85% into Zone 1 self section, and Zone 2 is a 125%, Zone 3 is a 225%. Which's $15{\sim}25%$ include current transformer error 5%, potential transformer 5%, relay calculation error 5% and margin factor from the field experience. This paper is discussed transmission protective relay and relay setting rule of high voltage power system and we verify the correctness relay setting rule with distance relay using Matlab simulation.

• 조명전기설비학회논문지
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• 제29권7호
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• pp.80-86
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• 2015

As wind farm outputs depend on natural wind resources that vary over space and time, spatial correlation analysis is needed to estimate power outputs of wind generation resources. As a result, geographic information such as latitude and longitude plays a key role to estimate power outputs of spatially distributed wind farms. In this paper, we introduce spatial correlation analysis to estimate the power outputs produced by wind farms that are geographically distributed. We present spatial correlation analysis of empirical power output data for the JEJU Island and ERCOT ISO (Texas) wind farms and propose the Correlation Decay Distance (CoDecDist) model based on geographic correlation analysis to enhance the estimation of wind power outputs.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 하계학술대회 논문집 A
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• pp.154-155
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• 2002

The demand of the power and gas energy have been rapidly increasing with the industralization, therefore, the area where buried pipelines run parallel with the adjacent power lines and cross them increases in Seoul as well as other cities. These situation cause AC interference from the power lines. However, there aren't any standards to preserve the pipelines from AC interference in Korea. This study introduces the separation distance to protection of buried pipeline from arc strikes caused by power line ground fault current. And this study examines and compares the arc distance through case study.

• Journal of Magnetics
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• 제21권1호
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• pp.102-109
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• 2016

In this paper, the theoretical and experimental characteristics of magnetic and electric fields in the vicinity of high voltage lines are investigated. To realize these measurements and calculations, we have developed some equations for two overhead power line configurations of 150 kV (single circuit, double circuit), based on Biot-savart law, image and Maxwell theories, in order to calculate the magnetic and electric fields. The measurements were done to a maximum distance from the tower of 50 m, at a height of 1m from the ground. These experiments take into consideration the real situations of the power lines and associated equipment. The experimental results obtained are near to that of the Biot-Savart theoretical results for a far distance from the tower; and for a distance close to the power line, the results from the image theory are in good agreement with the experimental results.

• 대한전기학회논문지:전력기술부문A
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• 제52권8호
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• pp.437-443
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• 2003

In this paper an expert system is developed to decide the resetting area of protective devices in power transmission systems. A configuration change in power transmission networks from a substation extension such as new line or bus addition need resetting of protective devices around the point of configuration changes. To find the resetting area in complex power system is very difficult, especially when the distance protective relays are considered to be reset. The proposed expert system, in this paper to find the resetting area has many rules based on the changes of fault currents and apparent factors from the power system alteration. It solves the problem to find relay resetting area using the network information in the database and the rule-base. The case study shows a result of the problem to find relay resetting area in KEPCO system when there is any configuration change.

• Current Optics and Photonics
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• 제7권1호
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• pp.1-14
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• 2023

Wavefront-coding imaging can achieve high-quality imaging along with a wide range of defocus. In this paper, the anti-laser detection and damage performance of wavefront-coding imaging systems using different asymmetric phase masks are studied, through modeling and simulation. Based on FresnelKirchhoff diffraction theory, the laser-propagation model of the wavefront-coding imaging system is established. The model uses defocus distance rather than wave aberration to characterize the degree of defocus of an imaging system. Then, based on a given defocus range, an optimization method based on Fisher information is used to determine the optimal phase-mask parameters. Finally, the anti-laser detection and damage performance of asymmetric phase masks at different defocus distances and propagation distances are simulated and analyzed. When studying the influence of defocus distance, compared to conventional imaging, the maximum single-pixel receiving power and echo-detection receiving power of asymmetric phase masks are reduced by about one and two orders of magnitude respectively. When exploring the influence of propagation distance, the maximum single-pixel receiving power of asymmetric phase masks decreases by about one order of magnitude and remains stable, and the echodetection receiving power gradually decreases with increasing propagation distance, until it approaches zero.

• 한국정보통신설비학회:학술대회논문집
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• 한국정보통신설비학회 2007년도 학술대회
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• pp.215-218
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• 2007

In this paper, we have analyzed the effects from the change of separation distance between grounding equipment at end of telecommunication line and the inducting facilities in power inducting situation. In the result of measurement, we can see that as the separation distance between grounding equipment ant end of telecommunication line and the inducting facility become longer, the induced noise level and PIF level is decreased. From the another experiment results about the effect of changing the impedance size in both ends of telecommunication line, however, we already knew that as the ground impedance at either end of the telecommunication line become grower, the noise level is increased, and as the ground impedance at either end of the telecommunication line become smaller, the noise level is decreased. Hence we can not define the relationship exactly between separation distance from inducting facility to inducted facility and the induced noise level because when the grounding equipment is moved, its impedance size is changed too. In conclusion, changing the separation distance between grounding equipment at end of telecommunication line and the inducting facilities have not influence on the induced noise level.

• 한국멀티미디어학회논문지
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• 제10권4호
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• pp.516-526
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• 2007

무선 메쉬 네트워크는 WLAN 기술뿐만 아니라, 센서 네트워크와의 연동을 통해 다양한 분야에 응용할 수 있으며, 유비쿼터스 네트워크 구현을 위한 핵심기술이라 할 수 있다. 그러나 WLAN은 ISM 대역을 전송 주파수 대역으로 사용하기 때문에, 최대 전력이 100mW로 제한된다. 최대 전력이 제한된 상황에서 WLAN기반의 메쉬 네트워크가 비용 효율적인 백본망의 역할을 수행하기 위해서는 장거리 전송을 위한 연구가 필수적이다. 따라서 본 논문에서는 실험 결과를 통해 무선 메쉬 네트워크 단점인 도달거리의 한계를 극복할 수 있는 방안을 제시하였으며 그 효과성을 보였다. 제안한 방법은 다양한 안테나의 적용 및 디바이스 드라이버의 함수 정의와 구현으로 장거리 전송과 전력효율을 높일 수 있었다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2010년도 춘계학술대회 논문집
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• pp.23-23
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• 2010

Because of power consumption increase, global warming, and limitation of installation, not only high reliability and interruption capability but also compact and light power apparatuses are needed. In this paper, various models that short and long gap distance were used to analyze E field of each model. Calculation value was estimated of flashover position. As a result, short and long gap distance that vacuum interrupter inner between move electrode and fix electrode not coincided flashover position of each model. short gap distance estimated flashover position at electrode edge. but long gap distance model confirmed $E_{max}$ value at center shield. in this paper was compared electric field value. and estimated of flashover position from electric field calculation.