• Communications for Statistical Applications and Methods
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• v.19 no.3
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• pp.405-414
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• 2012

In a stratified sample, the sampling frame is divided into non-overlapping groups or strata (e.g. geographical areas, age-groups, and genders). A sample is taken from each stratum, if this sample is a simple random sample it is referred to as stratified random sampling. In this paper, we study the bootstrap inference (including confidence interval) and test for a stratified population mean. We also introduce the bootstrap consistency based on limiting distribution related to the plug-in estimator of the population mean. We suggest three bootstrap confidence intervals such as standard bootstrap method, percentile bootstrap method and studentized bootstrap method. We also suggest a bootstrap test method computing the $ASL_{boot}$(Achieved Significance Level). The results of estimation are verified using simulation.

• Journal of Oral Medicine and Pain
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• v.33 no.3
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• pp.241-246
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• 2008

Lichen planus is a common, chronic inflammatory disease of the skin and mucous membrane for which no precise causes have been confirmed. But it is often connected with infections. Helicobacter pylori(H. pylori) among various bacteria has been associated with the cause of gastritis, peptic ulcer and gastric cancer. Considering the similarities of histological features between gastric ulcer and oral ulcers, it is resonable to assume that H. pylori might also be involved in the development oral mucosal ulceration. So we employed this study to investigate the possible involvement of H. pylori in the aetiology of erosive oral lichen planus. We analyzed detection rate of H. pylori in saliva of patients with erosive oral lichen planus by nested PCR. As a result, it revealed a significant difference statistically by showing positivity in 16 to 21(76.2%) saliva samples of patients group and in 11 of 44(25%) saliva samples of control group(P>0.001). We were able to suppose that H. pylori in saliva can be related to cause of erosive oral lichen planus.

• Journal of the Society of Naval Architects of Korea
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• v.29 no.1
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• pp.1-13
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• 1992

The objective of this study is to develop knowledge-based system for the preliminary design and midship section design of bulk carrier and to enhance the applicability of knowledge engineering in the field of Naval Architecture. First, expert system shell called E.1 is developed in C language. E.1 supports backward-chaining, automatic iteration procedure and reiterative inference mechanism for efficient application of knowledge-based system in structural design. Knowledge representation in E.1 includes IF-THEN rules, 'facts'and 'tables'. Second, knowledge bases for the principal particulars and midship section design are developed by experimental formula, design standard and experiential knowlege. Third, hybrid system combined this knowledge-based system with the optimization program of midship section is developed. Finally, the simplified design method utilizing the regression analysis of the optimum results of stiffened plate is developed for facilitating the design process. Using this knowledge-based system, the design process and results for Bulk carrier and stiffened plates are discussed. It is concluded that knowledge-based system is efficient for preliminary design and midship section design of the ship. It is expected that the performance of the CAD system would be enhanced if the better knowledge-base is accumulated in the E.1 tool.

• The Journal of the Acoustical Society of Korea
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• v.31 no.6
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• pp.391-398
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• 2012

In this paper, prediction of centrifugal fan was conducted through combination the hybrid CAA method which was used to predict the fan noise with the FRPM technique which was used to generate the broadband noise source. Firstly, flow field surround the centrifugal fan was computed using the RANS equations and noise source region was deducted from the computed flow field. Then the FRPM technique was applied to the source region for generation of turbulence which satisfies the stochastic features. The noise source of the centrifugal fan was modeled by applying the acoustic analogy to the synthesized flow field from the computed and generated flow fields. Finally, the broadband noise of the centrifugal fan was predicted through combination the modeled noise source with the linear propagation which was realized using the boundary element method. It was confirmed that the proposed technique is efficient to predict the tonal and broadband noises of centrifugal fan through comparison with the measured data.

• Journal of Korea Technology Innovation Society
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• v.20 no.3
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• pp.519-545
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• 2017

This study analyzed the factors influencing the technology transfer of Government-Funded Research Institutes from the perspective of resource-based view. In particular, we analyzed the effects of research resources, research capacity, and research results diffusion variables on technology transfer performance. The research resource variables affect the primary output of R&D (patents, research papers) but direct effect on the technology transfer performance was very weak. Among the research competency variables, patent-related variables such as patent registration, patent holdings have a significant effect on the technology transfer performance. However, the research papers have a negative effect on the technology transfer performance. The research results diffusion variables such as TLO organization and TLO budget may partly have a positive impact on technology transfer, but the statistical significance is not clear.

• Journal of the Korean Institute of Intelligent Systems
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• v.14 no.2
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• pp.142-149
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• 2004

It is important to retrieve exact information coinciding with user's need from lots of Usenet news and filter desired information quickly. Differently from email system, we must previously register our interesting news group if we want to get the news information. However, it is not easy for a novice to decide which news group is relevant to his or her interests. In this work, we present a service classifying user preferred news groups among various news groups by the use of Kohonen network. We first extract candidate terms from example documents and then choose a number of representative keywords to be used in Kohonen network from them through fuzzy inference. From the observation of training patterns, we could find the sparsity problem that lots of keywords in training patterns are empty. Thus, a new method to train neural network through reduction of unnecessary dimensions by the statistical coefficient of determination is proposed in this paper. Experimental results show that the proposed method is superior to the method using every dimension in terms of cluster overlap defined by using within cluster distance and between cluster distance.

• Journal of the Korea Society of Computer and Information
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• v.15 no.9
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• pp.19-24
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• 2010

The number of automobiles are continuously increasing in Korea since 1990's and it causes frustrating commuting traffic and holyday traffic. Meanwhile, the obsolete traffic signal control system is still under static control based on the aggregated traffic statistics thus it is not sufficiently adaptive in real world traffic situation that changes in real time. Thus, in this paper, we propose an adaptive signal control system using fuzzy control technology that can react to real time traffic situations. The method computes the priority of signal phases based on the number of waiting automobiles and occupying time on intersection using fuzzy membership functions. The phase with highest priority obtains "proceed" signal. Also, the duration of this "proceed" signal is determined based on the ratio of number of waiting automobiles of given phase and total number of waiting automobiles on intersection. In experiment, we show that the proposed fuzzy control system is better than the static control system for all sorts of traffic congestion situations by simulation.

• The Korean Journal of Applied Statistics
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• v.33 no.5
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• pp.527-540
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• 2020

While analyzing data, researching outliers, which are out of the main tendency, is as important as researching data that follow the general tendency. In this study we discuss the influence function for outlier discrimination. We derive sample influence functions of sample mean, sample variance, and sample standard deviation, which were not directly derived in previous research. The results enable us to mathematically examine the relationship between the empirical influence function and sample influence function. We can also consider a method to approximate the sample influence function by the empirical influence function. Also, the validity of the relationship between the approximated sample influence function and the empirical influence function is also verified by the simulation of random sampled data in normal distribution. As the result of a simulation, both the relationship between the two influence functions, sample and empirical, and the method of approximating the sample influence function through the emperical influence function were verified. This research has significance in proposing a method that reduces errors in the approximation of the empirical influence function and in proposing an effective and practical method that proceeds from previous research that approximates the sample influence function directly through empirical influence function by constant revision.

• Journal of the Korean Data and Information Science Society
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• v.20 no.2
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• pp.301-309
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• 2009

Multidimensional scaling(MDS) is a statistical multivariate analysis technique that is often used in information visualization for exploring similarities or dissimilarities in data. In order to analyse and visualize data, MDS measures the dissimilarities between objects and uses them or their mean if they are repeatedly measured. When there exist outliers or when the variation of data is too large, we can hardly get reliable results on the research using MDS. In this paper, we consider the MDS based on bootstrap method when the variation of data is large. Standardized residual sum of squares is considered as measuring goodness-of-fit of the model. A real data analysis is include to examine our approach.

• The Journal of Internal Korean Medicine
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• v.26 no.4
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• pp.753-760
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• 2005

목적 : 본 연구는 100명의 암환자를 대상으로 항암단의 항혈관형성 효과를 측정하기 위하여 고안되었다. 방법 : 100명의 암환자 전체의 치료전후의 VEGF, bFGF 및 혈소판 수치의 변화량을 측정하였고, 병기, 삶의 질 및 암종별로 환자를 나누어 각각의 치료전후의 VEGF, bFGF 및 혈소판 수치의 변화량을 측정하여 통계적 유의성을 살펴보았다. 결과 : 항암단으로 치료한 암환자의 bFGF 수치는 치료전 후 통계적으로 유의성 있게 감소하였다. 특히 유방암 환자에서 bFGF 수치의 감소가 눈에 띄었다. 비록 통계적으로 유의하지는 않았지만 VEGF수치도 항암단으로 치료 후 다소 감소하는 경향을 보였다. 결론 : 따라서 항암단이 암환자 치료에 있어 항혈관형성 약물로써 작용한다고 추론할 수 있다.