• Journal of Advanced Marine Engineering and Technology
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• v.39 no.8
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• pp.828-832
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• 2015

This study is conducted for the evaluation of corrosion and lifetime prediction of fire extinguishing pipelines in residential buildings. The fire extinguishing pipeline is made of carbon steel. Twenty-four samples were selected among all the fire extinguishing pipelines in a building; the selection was based on specimenspositions, pipeline diameters, and pipeline thickness. Analysis was conducted by using the results of visual inspection, electrochemical potentiodynamic anodic polarization test, pitting depth measurements, and extreme value statistics with the Gumbel distribution. The maximum pitting depth and remaining life were statistically predicted using extreme value statistics. During visual inspection, pitting corrosion was observed in several samples. In addition, extreme value statistics demonstrated that there were several pipelines that were very sensitive to pitting corrosion. However, the pitting corrosion was not critical in all the pipelines; thus, it was necessary to change only those pipelines that were severely corroded.

• The Korean Journal of Applied Statistics
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• v.22 no.2
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• pp.237-248
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• 2009

The probability of default on the credit evaluation study is represented as a linear combination of two distributions of default and non-default, and the distribution of the probability of default are generally known in most cases. Except the well-known Kolmogorov-Smirnov statistic for testing the identity of two distribution, Kuiper, Cramer-Von Mises, Anderson-Darling, and Watson test statistics are introduced in this work. Under the assumption that the population distribution is known, modified Cramer-Von Mises, Anderson-Darling, and Watson statistics are proposed. Based on score data generated from various probability density functions of the probability of default, the modified test statistics are discussed and compared.

• Journal of the Korean Society for information Management
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• v.26 no.3
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• pp.417-434
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• 2009

Statistics items required by National Library Statistics System are based on data for library evaluation and policy making of library management from a theoretical standpoint. However, It is realized there are differences between Statistics items required by National Library Statistics System and those can be collected at the field of public libraries. In accordance with this point, this paper contained an analysis of a working diary log of public libraries as a basic material able to collect data at the field of public libraries and also surveyed the present usage situation of Library Management Program able to automatically collect data to recognize that National Library Statistics is reliably or validly objective data. An analysis data of this research will be a basic material to plan the standard guide of a working diary log of public libraries from now on.

• Journal of the Korean Statistical Society
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• v.34 no.3
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• pp.173-183
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• 2005

The Box-Cox power transformation is generally used for variance stabilization. Recently, Shin and Kang (2001) showed, under the Box-Cox transformation, invariant properties to the original model under the large mean and relatively small variance assumptions in time series analysis. In this paper we obtain some invariant properties in spatial statistics. Spatial statistics, Invariant Property, Variogram, Box-Cox power Transformation.

• Communications for Statistical Applications and Methods
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• v.15 no.4
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• pp.615-631
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• 2008

Current credit evaluation models based on only financial data except non-financial data are used continuous data and produce credit scores for the ranking. In this work, some problems of the credit evaluation models based on transformed continuous financial data are discussed and we propose improved credit evaluation models based on categorized financial data. After analyzing and comparing goodness-of-fit tests of two models, the availability of the credit evaluation models for categorized financial data is explained.

• The Korean Journal of Applied Statistics
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• v.25 no.6
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• pp.917-923
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• 2012

We perform a comparison of time series models that include seasonal ARIMA, Fractional ARIMA, and Holt-Winters models; in addition, we also consider hourly and daily air passenger data. The results of the performance evaluation of the models show that the Holt-Winters methods outperforms other models in terms of MAPE.

• Journal of the Korean Data and Information Science Society
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• v.23 no.1
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• pp.143-150
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• 2012

Based on the student evaluation of teaching from 'A' university where students are graded by relative performance, we conducted a research on the effect of course characteristics in student evaluation of teaching. The results show that the score of student evaluation of teaching seems to be higher for those classes with more proportion of male students, higher grades, and smaller class sizes. From these results, we suggest an evaluation model which can control the effect of grade and sex. Also we illustrate the performance of the evaluation model by using a case study.

• Journal of Applied Reliability
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• v.11 no.2
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• pp.177-186
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• 2011

Traditionally, one uses a method of straight-line recognition to evaluate quality of product or service. One can satisfy with the product or service if their physical requirement of are met some criterions and can not satisfy them if their physical requirement are not met. Kano, et al(1984) introduce two dimensional Quality model to evaluate quality of product or service. They classify Quality Characteristic of product and service to three categories; satisfying quality, attractive quality, expected quality. In this paper, 17 evaluation features in 6 categories of smart-card are obtained from Focus-interview and Brainstorming and classified into 3 categories of quality model by Kano's two dimensional method. This classification is expected to provide a guideline for evaluation of smart-card.

• Journal of the Korean Data and Information Science Society
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• v.19 no.3
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• pp.789-800
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• 2008

Current credit evaluation models based on financial data make use of smoothing estimated default ratios which are transformed from each financial variable. In this work, some problems of the credit evaluation models developed by financial experts are discussed and we propose improved credit evaluation models based on the stepwise variable selection method and Box-Cox transformed data whose distribution is much skewed to the right. After comparing goodness-of-fit tests of these models, the validation of the credit evaluation models using statistical methods such as the stepwise variable selection method and Box-Cox transformation function is explained.

• Journal of the Korean Society of Safety
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• v.24 no.6
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• pp.7-12
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• 2009

This study focuses on the classification of fire equipments for certification based on the risk evaluation. In general, known statistics on fire equipment-related accidents needs to be used for risk evaluation. When statistics is not available, however, expected frequency and severity of accident for individual equipment can be taken into account in evaluating the related risks. Based on the level of inherent risks, each equipment is then classified into three categories for certification. For equipments that risk evaluation is not possible, characteristics of those products such as reliability are considered for classification. Once classified, each equipment is assigned an appropriate certification module.