• Journal of the Korean Data and Information Science Society
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• v.24 no.3
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• pp.437-444
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• 2013

The object of study is to verify the distributions of response packets of 3 portal sites such as Naver, Daum, Nate. The period of experiments is from May 19th 2010 to November 7th 2012 and the number of experiments is 4,642. The distributions of Naver, Nate are biomodals. The distribution of Daum has long right tails. 3 distributions are different under 1% significance level using chi-square test and two sample Kolmogorov-Smirnov test. From proportions and percentiles, Naver has a distribution with the largest values. Nate is the second place, and Daum has a distribution with the smallest values. We must make portal pages light to increase response speed including other technologies. We expect our results to activate competition among portal sites.

• Communications for Statistical Applications and Methods
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• v.3 no.2
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• pp.227-237
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• 1996

비중심 ${\chi}^2$분포의 누적분포함수의 계산은 ${\chi}^2$검정에서 요구되고 있는 새로운 접근방법으로 신경망 이론을 적용하기 위하여 입력층의 입력노드가 세개, 출력증의 축력노드가 한개 그리고 한개의 은닉층으로 구성된 다층 퍼셉트론 네트워크부터 역전파 알고리즘을 개발하여 비중심${\chi}^2$분포의 확률계산을 시도하였다. 정확성과 계산속도를 고려하여 기존의 방법과 비교한 결과 효율적임을 알 수 있다.

• Journal of the Korean Institute of Telematics and Electronics
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• v.21 no.3
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• pp.1-5
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• 1984

It is investigated that Mahalanobis distances are invariant under a proper transformation and interest MDs are distributed as non-central chi-square while it is well known that intraset MDs are distributed as central chi-square. And their moments have been expressed as simple polynomials whose coefficients satisfy straightforward recursive relations.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.8C
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• pp.681-688
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• 2007

Applying an appropriate received signal processing algorithm based on the channel characteristics is important to improve the receiver performance. Wireless channels in general exhibit various time-delay characteristics depending on their power delay profile. When the estimated channel power summation is used to determine the amount of time delay, a channel adaptive receiver structure can be implemented. In this paper, we derive a closed-form expression for the error probability of the channel classification when the estimated channel power summation is used to classify channel groups having different time delay characteristics, and present the performance gain utilizing multiple estimation results.

• Asia Marketing Journal
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• v.9 no.2
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• pp.23-47
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• 2007

A new chi-square test is proposed to assess significance of attributes for nonparametric conjoint models. The key idea is to form subsets of rankings and test the dependence between the attribute levels and the sets of rankings. The null hypothesis states that the rankings for profiles with the focal attribute are distributed randomly among the sets of rankings. The approach is simple, easy to use, and can be applied at the individual level as well as at the aggregate level. It can be used for the trade-off approach as well as for the full profile approach.

• The KIPS Transactions:PartA
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• v.9A no.2
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• pp.267-270
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• 2002

The evaluation of the cumulative distribution function of the noncentral $\chi^2$ distribution is required in approximate determination of the power of the $\chi^2$ test. This article provides an algorithm for evaluating the noncentral $\chi^2$ distribution function in terms of a single "central" $\chi^2$ distribution function and compared various approximations.ximations.

• The Transactions of the Korea Information Processing Society
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• v.4 no.2
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• pp.483-490
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• 1997

The evalution of the cumulative distridution function of the noncentral $X^2$ distribution required in approxi-mate determination of the $X^2$ test. Many approximations to the cumulative distribution function of the noncentral $X^2$ distribution have been suggested. However, in selecting an approximations both simplicity and accuracy should be considered. In this note we compared various approximations in terms of accuracy and efficiency.

• Journal of the Korean Data and Information Science Society
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• v.23 no.2
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• pp.227-234
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• 2012

Hamming distances in medical science are used for the diagnosis of diseases. The differences of the distances, however, are often very small, and is not in the general statistical form such as normal or chi-square distribution. In this study, we explore the characteristics and significance of the differences of Hamming distances generated in medical diagnosis.

• Journal of the Korean Data and Information Science Society
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• v.25 no.6
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• pp.1231-1239
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• 2014

In this paper we analyse the distributions of the number of goals scored by home teams and away teams in K-league soccer outcomes between 1983 and 2012. Real soccer data is explained in K-league using statistical distributions such that Poisson, negative binomial, extreme value and zero inflated Poisson. How close the goals of home and away fits the different distributions are tested by performing chi-square goodness of fit tests. According to these tests, the Poisson distribution gives the best fit to the home goals data. But it is best to model the away goals data on zero inflated Poisson distribution. Also, there is some weak evidence of the dependence for home and away goals.

• The Korean Journal of Applied Statistics
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• v.20 no.1
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• pp.1-9
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• 2007

This investigation on the change of the daily maxima temperature in Seoul, Daegu, Chunchen, Youngchen was triggered by news items such as the earth is getting warmer and a recent news item that said that Korea is getting warmer due to this climatic change. A statistical analysis on the daily maxima for June over this period in Seoul revealed a positive trend of 1.1190 centigrade over the 45 years, a change of 0.0249 degrees annually. Due to the large variation on these maximum temperatures, one can raise the question on the significance of this increase. To check the goodness of fit of the proposed extreme value model, we shown a Q-Q plot of the observed quantiles against the simulated quantiles and a probability plot. And we calculated statistics each month and a tolerance limit. This is tested through simulating a large number of similar datasets from an Extreme Value distribution which described the observed data very well. Only 0.02% of the simulated datasets showed an increase of this degrees or larger, meaning that the probability is very low for such an event to occur.