• Journal of the Korean Data and Information Science Society
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• 제15권1호
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• pp.211-218
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• 2004

The subject of assessing whether a data set is from a specific distribution has received a good deal of attention. This topic is critically important for uniform distributions. Several parametric tests are compared. These tests also can be used in testing randomness of a sample. Anderson-Darling $A^2$ statistic is found to be most powerful.

• Communications for Statistical Applications and Methods
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• 제12권2호
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• pp.463-472
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• 2005

In this paper, the problem of estimating a p-variate (p $\ge$4) normal mean vector is considered in decision-theoretic set up. Using a simple property of the noncentral chi-square distribution, a sequence of estimators dominating the Lindley type estimator with the cases of unknown covariance matrices has been produced and each improved estimator is better than previous one.

• 응용통계연구
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• 제23권6호
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• pp.1057-1065
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• 2010

In this paper we discuss some cautionary notes in using the Pearson chi-squared test statistic for the goodness-of-fit of the ordinal response model. If a model includes continuous type explanatory variables, the resulting table from the t of a model is not a regular one in the sense that the cell boundaries are not fixed but randomly determined by some other criteria. The chi-squared statistic from this kind of table does not have a limiting chi-square distribution in general and we need to be very cautious of the use of a chi-squared type goodness-of-t test. We also study the limiting distribution of the chi-squared type statistic for testing the goodness-of-t of cumulative logit models with ordinal responses. The regularity conditions necessary to the limiting distribution will be reformulated in the framework of the cumulative logit model by modifying those of Moore and Spruill (1975). Due to the complex limiting distribution, a parametric bootstrap testing procedure is a good alternative and we explained the suggested method through a practical example of an ordinal response dataset.

• 조명전기설비학회논문지
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• 제17권3호
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• pp.103-109
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• 2003

전력계통의 자동화에 있어 측정되는 데이터의 정확성은 기본적으로 확립되어야 할 요건이다. 측정된 데이터는 통신 장애나 기기 자체의 오동작으로 인해 오차를 포함할 수 있으며, 이러한 오차는 상태추정에 의해 줄어들 수 있으나, 잘못 측정된 일부 값에 의해 상태추정의 전반적인 신뢰도가 저하될 수 있다. 본 논문에서는 가중최소 상태추정과 카이스퀘어 이론에 근거한 잘못 측정된 데이터의 검출 알고리즘이 제안되었으며, 이를 국내 154kV 변전소에 적용하였다. C 언어와 비쥬얼 베이직을 사용하여 GUI 환경의 시뮬레이터를 개발하였으며, 다른 운용 시스템과의 연계를 고려하여 TCP/IP 프로토콜을 탑재하였다.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2000년도 하계종합학술대회 논문집(1)
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• pp.197-200
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• 2000

This paper presents a mathematical model of the output of Rake receiver of W-CDMA signals for various outdoor channel environment and different bandwidths. This mathematical model is represented as Rayleigh and noncentral chi distribution with 3 degrees of freedom. Those are obtained from the statistics of numerically generated signals. We employ Chi-square test to show how the mathematical model fits signal statistics, and confirmed that this model is appropriate for representing W-CDMA signals.

• Journal of the Korean Statistical Society
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• 제30권1호
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• pp.63-76
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• 2001

An adaptive estimation and testing method is proposed for comparing dispersions among several ordered groups. Based upon the large sampling theory for nonparametric quartile estimators, we derive the order restricted estimators and construct a simple test statistic. This test statistic has a mixture of several chi-square distributions as its asymptotic null distribution. The proposed test is illustratively applied to survival time data for the patients with carcinoma of the oropharynx.

• 한국항공우주학회지
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• 제38권8호
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• pp.781-789
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• 2010

GPS/INS 통합시스템의 고장검출에는 카이제곱 분포 기반의 알고리즘이 일반적으로 사용된다. 본 논문에서는 기존의 RAIM (Receiver Autonomous Integrity Monitor)과 카이제곱 분포 기반의 알고리즘을 결합하여 무인기용 저급 프로세서에 적용하기 위해 단순화시킨 GPS/INS 고장검출 알고리즘을 제안한다. 제안한 알고리즘의 검증을 위해 고장모델을 사용하여 그 결과를 나타내었다.

• 한국산업정보학회논문지
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• 제14권3호
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• pp.37-43
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• 2009

스테가노그래피는 인터넷에서 은닉메시지가 보내어지는 사실 자체를 숨기는 것이다. 일반적인 스테간 분석은 스테고 신호의 통계량에서 갑작스런 변화인 이상치를 감지하는 것이다. 혼합된 스테고 이미지에 비해 은닉자료가 매우 작은 경우 은닉된 자료의 감지와 위치를 찾아내는 일반적이고 효과적인 감지기법 즉, 이웃한 4개의 픽셀값을 이용한 삽입용량값과 카이스퀘어 검사기법 등을 함께 고려하는 개선된 방법을 제시한다.

• 대한치과보철학회지
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• 제30권2호
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• pp.273-285
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• 1992

The purpose of this study was to evaluate facial form, arch form and tooth form in young adults to determine if a correlation exists. 115 subjects who had healthy natural maxillary incisors and good occlusion consisted of 71 males and 44 females ranging from 20-30 years of age. Facial photographs and, intraoral photographs of upper anterior teeth and dental casts of upper jaws were taken to demonstrate facial form, dental arch form and tooth form. Form analysis is determined by comparing the ratio of the widths of the faces, dental archs and the teeth. The Chi-square test of independence between facial form, arch form and tooth form, was executed and the significance level determined. The results were as follows : 1. The distribution of facial forms was 66.1% square-tapering, 27.0% square, 5.2% ovoid, 2% tapering-square. 2. The distribution of tooth forms was 65.2% ovoid, 20.0% square-tapering, 11.3 % tapering-square, 3.5 % square. 3. The distribution of arch forms was 50.4 % square-tapering, 48.7 % tapering, 0.9 % reverse tapering-square. 4. There was no large differences in the distribution of facial forms, dental arch forms and tooth-forms between male and female. 5. No relationship existed between the tooth form and the facial form. 6. No relationship existed between the facial form and the dental arch form. 7. No relationship existed between the tooth form and the dental arch form. 8. This gave the impression that dental arch form and facial form could not be used as a true index in tooth selection.

• 비교문화연구
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• 제43권
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• pp.459-483
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• 2016

The main objective of this paper is to test the major prediction of the Aspect Hypothesis on interlanguage narratives collected from 171 Ibibio ESL learners in a classroom setting using sets of picture stories. Aspect Hypothesis predicts that lexical aspectual classes of verbs would determine the pattern of acquisition and distribution of tense-aspect morphology at the very early stages of L2 acquisition of tense-aspect verbal morphology. That is, telic verbs would be marked with the past tense-aspect verbal morphology before atelic verbs in the interlanguage of ESL learners irrespective of their L1 background. The results of our data analyses show a significant effect from the lexical aspect on the acquisition and distribution of tense-aspect morphology with chi-square statistics of ($x^2=196.92$,df = 6, n = 1664, p = <.0001). However, the effect of the lexical aspect is shown to be more prominent among Ibibio ESL learners at higher levels of proficiency. This is contrary to the prediction regarding Aspect Hypothesis. The paper concludes that the influence of the lexical aspect on the pattern of acquisition and distribution of tense-aspect morphology may be universal but the actual point along the developmental pathway when such influence is obtainable is yet to be determined. This calls for more research into the pattern of the L2 acquisition of tense-aspect verbal morphology.