• Journal of Electrical Engineering and information Science
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• 제1권2호
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• pp.52-57
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• 1996

Detection of arcing high impedance faults has been a perplexing in the power distribution protection. Transient analysis of distribution disturbances for fault discrimination from other normal events is important for a secure protection of the power system. A simple parameter of wave form distortion quantification is used to analyze the behaviors of arcing faults and normal distribution disturbances. Theoretical perspectives of the transients were studied and actual disturbances were examined. From this investigation, a discrimination guideline based on the revised crest factor is developed. The discrimination method has a high potential to enhance the reliability and security for the distribution system protection.

• 자원환경지질
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• 제36권3호
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• pp.201-212
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• 2003

한반도 남동부의 경상분지에 한국지질자원연구원의 지진관측망을 비롯한 관측소들이 급격히 증가함에 따라, 지진관측의 능력이 최근에 들어 크게 향상되었다. 그러나, 빈번한 중소규모의 화약발파에 의한 진동이 다수 관측되고 있다. 따라서, 이 지역에서 자연지진과 발파에 의한 인공지진의 식별이 중요한 문제로 부상하였다. 이 지역에서의 인공지진과 자연지진의 적절한 식별법을 확립하기 위하여 소규모의 지역지진 43개와 이에 대응되는 인공지진 43개를 선정하였다. 이 연구에서는 주파수 영역에서 Pg파, Sg파 및 Lg파의 스펙트럼 진폭비를 이용하는 기법들이 폭 넓게 검토되었다. 그들 중 Pg/Lg 스펙트럼 진폭비를 이용하는 방법이 가장 좋은 식별법으로 나타났다. 또한, 식별능력을 향상시키기 위하여 Pg/Lg 스펙트럼비에 다변량 판별분석법을 적용하였다. 거리보정이 안된 수직성분에 비하여 거리에 대한 감쇠효과를 보정한 3성분의 Pg/Lg비에 판별분석법을 적용했을 때의 판별능력은 뚜렷한 증가를 보인다. 주파수 대역 4-l4Hz의 범위에서, 거리 보정한 3성분의 Pg/Lg비에 대한 판별분석의 결과 총 분류비율은 0.89%에 불과한 것으로 나타난다.

• Journal of the Korean Statistical Society
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• 제25권2호
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• pp.289-301
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• 1996

This paper suggests a new diagnostic measure for detecting influential observations in two group linear discriminant analysis(LDA). It is developed from an information theoretic point of view using the minimum discrimination information(MDI) methodology. MDI estimator of symmetric divergence by Kullback(l967) is taken as a measure of the power of discrimination in LDA. It is shown that the effect of an observation over the power of discrimination is fully explained by the diagnostic measure. Asymptotic distribution of the proposed measure is derived as a function of independent chi-squared and standard normal variables. By means of the distributions, a couple of methods are suggested for detecting the influential observations in LDA. Performance of the suggested methods are examined through a simulation study.

• 대한전기학회논문지:전력기술부문A
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• 제52권2호
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• pp.134-141
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• 2003

The power transformer is one of the very important electric facilities in power systems. Recently, current differential relay is widely used to protect such power transformer But if inrush occurs in transformer, relay can be tripped by judging like internal fault. Therefore the correct discrimination between internal winding fault, inrush and overexcitation should be performed. This paper presents a new protective relaying algorithm which discriminates inrush, internal faults and overexcitation of transformer modelled using BCTRAN and HYSDAT of EMTP. Discrimination between internal winding fault and inrush is revealed in simulation within 1/2 cycle after fault. Accordingly, it is evaluated that the proposed algorithm has better discrimination characteristics in various cases thin the current relaying for protection of transformer.

• 전기학회논문지
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• 제61권5호
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• pp.657-663
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• 2012

Recently, by increasing of devices which are sensitive to power quality, the deterioration of power quality has been accelerated. For this reason, the social and economic losses are increased. So not only correct measurement and evaluation, but also countermeasure for improvement of power quality is surely necessary for both electric power supplier and consumer. In this paper, the discrimination algorithm for events and variation occurred in distribution systems using S-transform is proposed. Firstly, we review for events and variations that occur in distribution system. Next, we simulate events and variations on various conditions using ElectroMagnetic Transient Program(EMTP). For the simulation, the IEEE 13 Node Test Feeder and KEPCO's distribution system is modeled. Finally, for the analysis, a modified wavelet transform known as S-transform is adopted to find out the characteristics of each events and variations.

• Communications for Statistical Applications and Methods
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• 제19권6호
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• pp.837-847
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• 2012

Inverse Gaussian distribution is widely used in applications to analyze and model right-skewed data. To assess the appropriateness of the distribution prior to data analysis, Mudholkar and Tian (2002) proposed an entropy-based test of fit. The test is based on the entropy power fraction(EPF) index suggested by Gokhale (1983). The simulation results report that the power of the entropy-based test is superior compared to other goodness-of-fit tests; however, this observation is based on the small-scale simulation results on the standard exponential, Weibull W(1; 2) and lognormal LN(0:5; 1) distributions. A large-scale simulation should be performed against various alternative distributions to evaluate the power of the entropy-based test; however, the use of a theoretical method is more effective to investigate the powers. In this paper, utilizing the information discrimination(ID) index defined by Ehsan et al. (1995) as a mathematical tool, we scrutinize the power of the entropy-based test. The selected alternative distributions are the gamma, Weibull and lognormal distributions, which are widely used in data analysis as an alternative to inverse Gaussian distribution. The study results are provided and an illustrative example is analyzed.

• Journal of Communications and Networks
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• 제8권3호
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• pp.275-285
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• 2006

Suitable for multi-input multi-output (MIMO) communications, the joint beamforming space-time block coding (JBSTBC) scheme is proposed for high-speed downlink transmission. The major functionality of the scheme entails space-time block encoder and joint transmit and receive eigen-beamformer (EBF) incorporating with block-ordered layered decoder (BOLD), and its operating principle is described in this paper. Within these functionalities, the joint EBFs will be utilized for decorrelating fading channels to cause an enhancement in the spatial diversity gain. Furthermore, to fortify the capability of layered successive interference cancellation (LSIC) in block-ordered layered decoding process, this paper will develop a simple ad-hoc transmit power discrimination scheme (TPDS) based on a particular power discrimination function (PDF). To confirm the superior behavior of the proposed JBSTBC scheme employing ad-hoc TPDS, computer simulations will be conducted under various channel conditions with the provision of detailed mathematical derivations for clarifying its functionality.

• 응용통계연구
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• 제20권1호
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• pp.79-89
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• 2007

Arizono와 Ohta(1989)에 의해 소개된 정규성 검정은 쿨백-라이블러 판별정보를 이용하고 있으며, 검정통계량의 유도에 기반이 되는 판별정보의 추정량을 얻기 위해 Vasicek(1976)의 표본엔트로피와 분산의 최대가능도 추정량을 사용했다. 그런데 두 추정량은 편향성을 가지게 되므로 보다 정확한 판별정보의 추정을 위해 비편향 추정량을 사용하는 것이 바람직하다. 본 논문에서는 편향을 수정한 엔트로피 추정량과 분산의 균일최소분산비편향 추정량을 사용하여 판별정보의 추정량을 구하고 이로부터 유도되는 검정통계량을 사용하는 개선된 정규성 검정을 제시한다. 제안한 검정의 특성을 규명하고 검정력 비교를 위해서 모의실험을 수행한다.

• 식품과학과 산업
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• 제52권1호
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• pp.20-31
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• 2019

Sensory perception of food/beverage products is one of the most important quality factors to determine consumer acceptability and thus sensory discrimination methodology has been a vital tool for quality management. Signal detection theory(SDT) and Thurstonian modeling provide the most advanced psychometric approach to modeling various discrimination methods. In these theories, perceptual and cognitive decisional factors are considered so that, a fundamental measure of sensory difference (d') can be computed, independent of test methods used. In this paper, sensory discrimination analysis based on SDT and Thurstonian modeling is introduced for more accurate and systematic applications of sensory and hedonic quality management in industry. Ways to realize the statistical power and relative sensitivity of sensory discrimination methods theorized in SDT and Thurstonian modeling in practice, are also discussed by using a case study of the Nongshim quality management program for drinking water in which SDT A-Not A test methodology was further optimized.

• Communications for Statistical Applications and Methods
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• 제4권1호
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• pp.229-241
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• 1997

We consider discrimination curve and minimum dwell time for Poisson distribution and Poisson-power function distribution. Let the random variable X has Poisson distribution with mean .lambda.. For the hypothesis testing H$\_$0/:.lambda. = t vs. H$\_$1/:.lambda. = d (d$\_$0/ if X.leq.c. Since a critical value c can not be determined to satisfy both types of errors .alpha. and .beta., we considered discrimination curve that gives the maximum d such that it can be discriminated from t for a given .alpha. and .beta.. We also considered an algorithm to compute the minimum dwell time which is needed to discriminate at the given .alpha. and .beta. for the Poisson counts and proved its convergence property. For the Poisson-power function distribution, we reject H$\_$0/ if X.leq..'{c}.. Since a critical value .'{c}. can not be determined to satisfy both .alpha. and .beta., similar to the Poisson case we considered discrimination curve and computation algorithm to find the minimum dwell time for the Poisson-power function distribution. We prosent this algorithm and an example of computation. It is found that the minimum dwell time algorithm fails for the Poisson-power function distribution if the aiming error variance .sigma.$\^$2/$\_$2/ is too large relative to the variance .sigma.$\^$2/$\_$1/ of the Gaussian distribution of intensity. In other words, if .ell. is too small, we can not find the minimum dwell time for a given .alpha. and .beta..