• The Korean Journal of Applied Statistics
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• v.17 no.3
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• pp.499-505
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• 2004

The Pareto diagram analysis of the experimental data by the two level orthogonal arrays has been used widely in practice since it is a graphical, quick and easy method to analyze experimental results, which does not use the analysis of variance to screen significant effects. For the analysis of the experimental data by $L_{18}(2 \times 3^7)$ orthogonal array, Park(1996) proposed Pareto ANOVA in which the size of effects is defined by the mean squares of effects and the Pareto principle is used. In this paper, a new approach of the Pareto diagram analysis of the experimental data by $L_{18}(2 \times 3^7)$ orthogonal array is proposed. The main idea is to partition the size of three level effects by that of linear and quadratic orthogonal contrasts of those effects.

• Proceedings of the Korean Statistical Society Conference
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• 2005.05a
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• pp.291-298
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• 2005

지속성 외래 복막투석은 말기 신부전 환자들에게 널리 시행하는 신 대체 요법으로, 복막투석 환자에게서 주된 합병증으로 일어나는 단백질-열량 영양실조를 치료하기 위하여 아미노산을 복강 내로 주입하는 치료방법이다. 이현석 등(2004)의 연구에서는 아미노산 복막 투석액(IPAA)이 영양실조 환자들에게 실제로 영양상태에 미치는 영향을 평가하기 위하여 지속성 외래 복막투석 환자 43명을 12개월 동안 3개월 주기로 관측하여 얻어낸 반복측정자료를 바탕으로 IPAA의 효과 여부에 따라 반응군과 비반응군을 분류하였다. 본 논문에서는 이러한 두 그룹을 효과적으로 분류할 수 있는 분류기준변수들을 찾아내고 이 분류기준변수의 값을 바탕으로 새로운 환자에게 IPAA의 투여 여부를 진단할 수 있는 여러 분류방법들을 고찰하여 비교 연구하였다. 모수적인 방법으로 선형판별분석, 이차판별분석 및 로지스틱 판별분석을 소개하고 비모수적인 방법으로 support vector machine(SVM)을 소개하여 분류분석의 결과를 비교하여 두 그룹을 최소한의 오류로 분류하는 방법을 제안하였다.

• The Korean Journal of Applied Statistics
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• v.24 no.1
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• pp.61-69
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• 2011

In GARCH context, the conditional variance (or volatility) is of a quadratic function of the observation process. Examine standard ARCH/GARCH and their variant models in terms of quadratic formulations and it is interesting to note that most models in GARCH context have contained neither the first order term nor the interaction term. In this paper, we consider three models possessing the first order and/or interaction terms in the formulation of conditional variances, viz., quadratic GARCH, absolute value GARCH and bilinear GARCH processes. These models are investigated with a view to model comparisons and applications to financial time series in Korea

• Journal of the Korean Electrochemical Society
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• v.10 no.1
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• pp.20-24
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• 2007

Lithium ion secondary battery has been applied widely to portable devices, and has been studied for application to high power electric cell system such as power tool or hybrid electronic vehicle. The structure change of the electrodes materials occur when lithium ions move between electrodes. Neutron or X-rays can analyze the structure of electrode. The advantage of X-rays is convenient in test. However X-rays is scattered by electron cloud in atoms. Therefore, The elucidation for correct position of lithium is difficult with X-rays because lithium has small atomic weight. Neutron analysis techniques could solve this problem. In this review, We wish to discuss about structure analysis and the principle of structural characterization method using neutron beam source.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 1994.05a
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• pp.28-38
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• 1994

분류층 가스화기 설계를 위한 일차연구로서 가스화기 이차공기 주입방법에 따른 비반응 난류장에 대한 수치해석을 검사체적에 기초한 유한차분방법을 이용하여 수행하였다. 압력과 속도의 연계문제는 SIMPLEC 알고리즘을, 레이놀즈 전단력은 k-$\varepsilon$ 난류모델을 사용하였다. 입자궤적 계산은 공기역학적 항력만을 고려하였으며 비선형적인 공기저항력에 의한 난류변동상관모델은 고려치 않았다. 이차공기 주입방법(parallel injection과 nonparallel 3$0^{\circ}C$ injection)에 따른 수치해석을 수행하여 Ar tracer의 질량분율에 대한 실험자료와 비교하여 만족할 만한 결과를 얻었으며 이차공기의 주입각 및 기타 제반변수에 따른 유동장 변화를 분석하였다.

• The Korean Journal of Applied Statistics
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• v.5 no.1
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• pp.103-111
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• 1992

The projection pursuit method has been gussested as a technique for the analysis of the multivariate data. This method seeks out interesting linear projections of the multivariate data onto a line of a plane to solve the curse or dimensionality. In this paper we developed the discriminant analysis by using the projection method and simulations were used for comparison between this and other existing discriminant analysis methods.

• Communications for Statistical Applications and Methods
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• v.17 no.1
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• pp.67-77
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• 2010

In multinomial scheme with step-wise sampling, maximum likelihood estimates of multinomial probabilities are improved when some frequencies are merged. In this study, for cell probabilities in a I by J independent contingency tables, exact MLE and step-wise estimation methods are applied and the results are compared using MSE and Bias.

• Journal of Convergence for Information Technology
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• v.10 no.11
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• pp.98-106
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• 2020

This study was conducted to identify the factors influencing the severity of pressure injuries of patients with pressure injuries admitted to acute university hospital. This study was a secondary analysis on the data of the study conducted to identify the factors influencing the deterioration of pressure injuries during hospitalization. The data were collected by retrospectively examining the medical records of patients with pressure injuries who were 18 years of age or older and who were admitted to acute university hospital from May 2017 to November 2018. We used data from 472 patients with pressure injuries at admission for this secondary analysis. In order to identify the factor influencing of severe pressure injuries compare to superficial pressure injuries, we analyzed the data using logistic regression analysis. As a result of the study, gender, body temperature, and patient's movement were identified as factors affecting severe pressure injuries. Therefore, special care is necessary to increased the number of position change for inpatients with pressure injuries, especially for patients with decreased mobility.

• The Korean Journal of Applied Statistics
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• v.33 no.5
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• pp.569-578
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• 2020

By estimating conditional quantile functions of the response, quantile regression (QR) can provide comprehensive information of the relationship between the response and the predictors. In addition, kernel quantile regression (KQR) estimates a nonlinear conditional quantile function in reproducing kernel Hilbert spaces generated by a positive definite kernel function. However, it is infeasible to use the KQR in analysing a massive data due to the limitations of computer primary memory. We propose a divide and conquer based KQR (DC-KQR) method to overcome such a limitation. The proposed DC-KQR divides the entire data into a few subsets, then applies the KQR onto each subsets and derives a final estimator by aggregating all results from subsets. Simulation studies are presented to demonstrate the satisfactory performance of the proposed method.

• The Korean Journal of Applied Statistics
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• v.14 no.2
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• pp.401-413
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• 2001

이차원 분할자료에 대해서 행과 열의 관계를 저차원상에 시각적으로 표현하는 탐색적대응분석에 대하여 붓스트랩방법의 사용가능성을 살펴보았다. 기존의 탐색적 면만이 강조되어 왔던 대응분석에서 좌표점의 변이와 좌표점간의 거리에 대한 통계적 추론을 붓스트랩방법으로 해결할 수 있음을 보이고 또한 좌표축의 설명력에 대하여 붓스트랩신뢰구간의 포함확률의 일치성을 모의실험을 통해 제시하였다.