• Title/Summary/Keyword: Y Factor Method

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Power Factor Compensation System based on Voltage-controlled Method for 3-phase 4-wire Power System (3상 4선식 전력계통에서 전압제어 방식의 역률보상시스템)

  • Park, Chul-woo;Lee, Hyun-woo;Park, Young-kyun;Joung, Sanghyun
    • Journal of the Institute of Electronics and Information Engineers
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    • v.54 no.8
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    • pp.107-114
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    • 2017
  • In this paper, a novel power factor compensation system based on voltage-controlled method is proposed for 3-phase 4-wire power system. The proposed voltage-controlled power factor compensation system generates a reactive power required for compensation by applying a variable output voltage by a slidac to a capacitor. In conventional power factor compensation system using the capacitor bank method, the power factor compensation error occurs depending on the load condition due to the limited capacity of the capacitors. However, the proposed system compensates the power factor up to 100% without error. In this paper, we have developed a voltage-controlled power factor compensation system and a control algorithm for 3-phase 4-wire power system, and verify its performance through simulation and experiments. If the proposed power factor compensation system is applied to an industrial field, a power factor compensation performance can be maximized. As a result, it is possible to reduce of electricity prices, reduce of line loss, increase of load capacity, ensure the transmission margin capacity, and reduce the amount of power generation.

Reduction factor of multigrid iterations for elliptic problems

  • Kwak, Do-Y.
    • Journal of the Korean Mathematical Society
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    • v.32 no.1
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    • pp.7-15
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    • 1995
  • Multigrid method has been used widely to solve elliptic problems because of its applicability to many class of problems and fast convergence ([1], [3], [9], [10], [11], [12]). The estimate of convergence rate of multigrid is one of the main objectives of the multigrid analysis ([1], [2], [5], [6], [7], [8]). In many problems, the convergence rate depends on the regularity of the solutions([5], [6], [8]). In this paper, we present an improved estimate of reduction factor of multigrid iteration based on the proof in [6].

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A Compensation of Color Eerror Caused by Dynamic Range Transformation of Images (생동도 변환으로 인한 화상의 색오차 보정)

  • 장종국;권기룡;안상호;송규익;이건일
    • Journal of the Korean Institute of Telematics and Electronics B
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    • v.33B no.4
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    • pp.124-130
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    • 1996
  • A compensation method of color error resulting from dynamic range transformation of color image is propsoed. The color error is measured using the CIE L a b uniform color space, and the color image is compensated to minimize it. The color error is significant in the dark region of image, which is caused by the lunimance scaling factor is relatively large in that case. In the proposed method, we weight the luminance scaling factor corresponding to luminnce to minimize the error. Because the weighting factor depends on luminace distribution of image, a decisio method of weighting factor using histogram is also proposed.

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A Bayesian Diagnostic Measure and Stopping Rule for Detecting Influential Observations in Discriminant Analysis

  • Kim, Myung-Cheol;Kim, Hea-Jung
    • Journal of the Korean Statistical Society
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    • v.29 no.3
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    • pp.337-350
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    • 2000
  • This paper suggests a new diagnostic measure and a stopping rule for detecting influential observations in multiple discriminant analysis (MDA). It is developed from a Bayesian point of view using a default Bayes factor obtained from the fractional Bayes factor methodology. The Bayes factor is taken as a discriminatory information in MDA. It is shown that the effect of an observation over the discriminatory information is fully explained by the diagnostic measure. Based on the measure, we suggest a stopping rule for detecting influential observations in a given training sample. As a tool for interpreting the measure a graphical method is sued. Performance of the method is used. Performance of the method is examined through two illustrative examples.

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Study on Analysis of Single Phase Induction Motor Considering Saturation Factor (포화계수를 고려한 단상 유도전동기의 해석에 관한 연구)

  • Cho, Su-Yeon;Kim, Kwang-Soo;Im, Jong-Bin;Ryu, Gwang-Hyeon;Oh, Se-Young;Ahn, Han-Woong;Lee, Ju
    • Proceedings of the KIEE Conference
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    • 2011.07a
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    • pp.846-847
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    • 2011
  • This paper presents the study on analysis of single phase induction motor characteristics by equivalent circuit. For high efficiency of single phase induction motor, the motor parameters used for equivalent circuit analysis is important. The accuracy of equivalent circuit analysis of motor depends on the circuit parameters like saturation factor. Therefore this paper proposed the analysis method considering saturation factor. The saturation factor was calculated by iteration routine and numerical method. this proposed method was verified by FEM analysis results and dynamo test results of the prototype model.

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A Study on the Effect of Micro Defect on Stress Intensity Factor of Through-Crack by Boundary Element Method (경계요소법을 이용한 관통균열의 응력확대계수에 미치는 미소결함의 영향에 관한 연구)

  • Seong, Gi-Deuk;Yang, Won-Ho;Jo, Myeong-Rae
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.24 no.3 s.174
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    • pp.560-566
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    • 2000
  • Many researchers have dealt with the problems of fracture mechanics. Generally, these researches are concerned with crack in isotropic material without other micro defects. Actual structure, however, may contain micro defects as well as crack in manufacture processing or operation. If it contains mi defects near a crack, some different characteristics will be appear in fracture behaviors of the crack. This study examines the effect of the micro defect on stress intensity factor of center slant crack rectangular plate subjected to uniform uniaxial tensile stress. In this study, boundary element method(BEM) is used for analysis in stress intensity factor(SIF).

Imputation Using Factor Score Regression

  • Lee, Sang-Eun;Hwang, Hee-Jin;Shin, Key-Il
    • Communications for Statistical Applications and Methods
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    • v.16 no.2
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    • pp.317-323
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    • 2009
  • Recently not even government polices but small town decisions are based on the survey data/information, so the most of government agencies/organizations demand various sample surveys in each fields for more detail information. However in conducting the sample survey, nonresponse problem rises very often and it becomes a major issue on judging the accuracy of survey. For that matters, one solution ran be using the administration data. However unfortunately most of administration data are restricted to the common users. The other solution can be the imputation. Therefore several method, of imputation are studied in various fields. In this study, in stead of the simple regression imputation method which is commonly used, factor score regression method is applied specially to the incomplete data which have the unit and item misting values in survey data. Here for simulation study, Consumer Expenditure Surveys in Korea are used.

Mathematical representation to assess the wind resource by three parameter Weibull distribution

  • Sukkiramathi, K.;Rajkumar, R.;Seshaiah, C.V.
    • Wind and Structures
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    • v.31 no.5
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    • pp.419-430
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    • 2020
  • Weibull distribution is a conspicuous distribution known for its accuracy and its usage for wind energy analysis. The two and three parameter Weibull distributions are adopted in this study to fit wind speed data. The daily mean wind speed data of Ennore, Tamil Nadu, India has been used to validate the procedure. The parameters are estimated using maximum likelihood method, least square method and moment method. Four statistical tests namely Root mean square error, R2 test, Kolmogorov-Smirnov test and Anderson-Darling test are employed to inspect the fitness of Weibull probability density functions. The value of shape factor, scale factor, wind speed and wind power are determined at a height of 100m using extrapolation of numerical equations. Also, the value of capacity factor is calculated mathematically. This study provides a way to evaluate feasible locations for wind energy assessment, which can be used at any windy site throughout the world.

Adaptive Leaky Factor Determination for Robust Video Transmission over Error-Prone Networks

  • Kim, Jun-Hyung;Hwang, Min-Cheol;Wang, Tae-Shick;Nam, Ju-Hun;Ko, Sung-Jea
    • Proceedings of the Korean Society of Broadcast Engineers Conference
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    • 2009.01a
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    • pp.263-266
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    • 2009
  • When video packets are transmitted over error-prone networks, the leaky prediction can be used to mitigate the effect of error propagation. The leaky factor provides trade-off between coding efficiency and error resilience in the leaky prediction. In this paper, we propose an improved leaky prediction method where the leaky factor is adaptively determined for each frame by minimizing the estimated end-to-end distortion at the encoder. Experimental results show that the proposed method with the adaptive leaky factor shows the better performance of the error robustness as compared with the conventional method.

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Database Construction to compute Representative Model of Load Power Factor in Large Scale Power System (대규모 전력계통의 부하역률 대표모델 산정을 위한 데이터베이스 구축)

  • Lee, Jung-Hee;Kim, Kwang-Wook;Cho, Jong-Man;Kim, Jin-O
    • Proceedings of the KIEE Conference
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    • 2002.11b
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    • pp.209-211
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    • 2002
  • This paper computes the regional, seasonal and hourly representative model of load power factor considering load characteristics of all 154/22.9 kV substations. An accurately computed representative model of load power factor is studied to present a precision improvement of power system analysis and the security of the system. The method to compute representative model of load utilizes the method of applicable moving average based on the method of flow average. The EMS data are used as the source to assess the load power factor.

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