• Communications for Statistical Applications and Methods
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• 제27권1호
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• pp.149-161
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• 2020

In this paper we extend the functional principal component analysis for real-valued random functions to the case of Hilbert-space-valued functional random objects. For this, we introduce an autocovariance operator acting on the space of real-valued functions. We establish an eigendecomposition of the autocovariance operator and a Karuhnen-Loève expansion. We propose the estimators of the eigenfunctions and the functional principal component scores, and investigate the rates of convergence of the estimators to their targets. We detail the implementation of the methodology for the cases of compositional vectors and density functions, and illustrate the method by analyzing time-varying population composition data. We also discuss an extension of the methodology to multivariate cases and develop the corresponding theory.

• Journal of Korean Neurosurgical Society
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• 제67권2호
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• pp.177-185
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• 2024

Objective : Delayed cerebral ischemia (DCI) is a major cause of disability in patients who survive aneurysmal subarachnoid hemorrhage (aSAH). Systemic inflammatory markers, such as peripheral leukocyte count and systemic immune-inflammatory index (SII) score, have been considered predictors of DCI in previous studies. This study aims to investigate which systemic biomarkers are significant predictors of DCI. Methods : We conducted a retrospective, observational, single-center study of 170 patients with SAH admitted between May 2018 and March 2022. We analyzed the patients' clinical and laboratory parameters within 1 hour and 3-4 and 5-7 days after admission. The DCI and non-DCI groups were compared. Variables showing statistical significance in the univariate logistic analysis (p<0.05) were entered into a multivariate regression model. Results : Hunt-Hess grade "4-5" at admission, modified Fisher scale grade "3-4" at admission, hydrocephalus, intraventricular hemorrhage, and infection showed statistical significance (p<0.05) on a univariate logistic regression. Lymphocyte and monocyte count at admission, SII scores and C-reactive protein levels on days 3-4, and leukocyte and neutrophil counts on days 5-7 exhibited statistical significance on the univariate logistic regression. Multivariate logistic regression analysis revealed that monocyte count at admission (odds ratio [OR], 1.64; 95% confidence interval [CI], 1.04-2.65; p=0.036) and SII score at days 3-4 (OR, 1.55; 95% CI, 1.02-2.47; p=0.049) were independent predictors of DCI. Conclusion : Monocyte count at admission and SII score 3-4 days after rupture are independent predictors of clinical deterioration caused by DCI after aSAH. Peripheral monocytosis may be the primer for the innate immune reaction, and the SII score at days 3-4 can promptly represent the propagated systemic immune reaction toward DCI.

• 응용통계연구
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• 제30권4호
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• pp.567-578
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• 2017

일반적으로 그룹화된 다변량자료는 다변량 분산분석(multivariate analysis of variance; MANOVA)을 사용하여 그룹 간 차이를 검정할 수 있다. 그러나 만약 다변량 분산분석의 기본적인 가정이 위배되면 이 방법은 적절하지 못하다. 이 경우 다양한 거리로부터 그룹화된 비유사성을 계산한 후 다차원척도법(multidimensional scaling; MDS), 거리분석(analysis of distance; AOD) 그리고 비모수적 기법인 순열검정(permutation test)을 적용하여 문제를 해결할 수 있다. 다차원척도법은 비유사성으로부터 개체들의 좌표를 계산해주며 거리분석은 이 좌표를 활용하여 그룹구조를 파악하는데 유용하다. 특히 비유사성의 측도로 유클리드 거리를 사용하면 거리분석은 다변량 분산분석과 수리적으로 매우 밀접한 연관관계를 맺는다. 따라서 본 연구에서는 그룹화된 비유사성에 다차원척도법과 거리분석을 적용하여 그룹 내와 그룹 간의 구조를 파악하고 순열검정을 위한 새로운 검정통계량을 제안하려 한다. 덧붙여 유클리드 거리를 활용한 비유사성을 통해 거리분석과 다변량 분산분석과의 수리적 연관성을 고찰하고자 한다.

• Journal of Nutrition and Health
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• 제45권6호
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• pp.600-612
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• 2012

Nutritional researchers world-wide are using large-scale sample survey methods to study nutritional health epidemiology and services utilization in general, non-clinical populations. This article provides a review of important statistical methods and software that apply to descriptive and multivariate analysis of data collected in sample surveys, such as national health and nutrition examination survey. A comparative data analysis of the Korea National Health and Nutrition Examination Survey (KNHANES) was used to illustrate analytical procedures and design effects for survey estimates of population statistics, model parameters, and test statistics. This article focused on the following points, method of approach to analyze of the sample survey data, right software tools available to perform these analyses, and correct survey analysis methods important to interpretation of survey data. It addresses the question of approaches to analysis of complex sample survey data. The latest developments in software tools for analysis of complex sample survey data are covered, and empirical examples are presented that illustrate the impact of survey sample design effects on the parameter estimates, test statistics, and significance probabilities (p values) for univariate and multivariate analyses.

• 한국산림과학회지
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• 제90권5호
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• pp.593-599
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• 2001

다변량분석법(주성분분석법, PCA)을 이용하여 무척추동물 군집에 백강균 처리가 미치는 영향을 검정하였다. 좌표공간내의 군집들간의 거리를 이용하여, 군집구조에 미치는 요인들의 영향을 통계 검정하였다. 백강균 처리는 낙엽과 토양의 무척추동물 군집에 유의한 영향을 주지 않았다.

• BMB Reports
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• 제37권4호
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• pp.487-492
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• 2004

The extent of codon usage in the protein coding genes of the mycobacteriophage, Bxz1, and its plating bacteria, M. smegmatis, were determined, and it was observed that the codons ending with either G and / or C were predominant in both the organisms. Multivariate statistical analysis showed that in both organisms, the genes were separated along the first major explanatory axis according to their expression levels and their genomic GC content at the synonymous third positions of the codons. The second major explanatory axis differentiates the genes according to their genome type. A comparison of the relative synonymous codon usage between 20 highly- and 20 lowly expressed genes from Bxz1 identified 21 codons, which are statistically over represented in the former group of genes. Further analysis found that the Bxz1- specific tRNA species could recognize 13 out of the 21 over represented synonymous codons, which incorporated 13 amino acid residues preferentially into the highly expressed proteins of Bxz1. In contrast, seven amino acid residues were preferentially incorporated into the lowly expressed proteins by 10 other tRNA species of Bxz1. This analysis predicts for the first time that the Bxz1-specific tRNA species modulates the optimal expression of its proteins during development.

• Natural Product Sciences
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• 제17권2호
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• pp.147-159
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• 2011

A high-performance liquid chromatography-electrospray ionization-tandem mass spectrometric method was developed to determine simultaneously eight marker constituents of Forsythiae fructus, and subsequently applied it to classify its two botanical origins. The marker compounds of Forsythia suspensa were phillyrin, pinoresinol, phillygenin, lariciresinol and forsythiaside; those of F.viridissima were arctiin, arctigenin and matairesinol. Separation of the eight analytes was achieved on a phenyl-hexyl column (150${\times}$2.0 mm i.d., 3 ${\mu}M$) using gradient elution with the mobile phase: (A) 10% acetonitrile in 0.5% acetic acid, (B) 40% aqueous acetonitrile. A few fragment ions specific to the types of lignans, among the product ions generated by collisonally induced dissociation (CID) of molecular ion clusters, such as [M-H]$^-$ or [M+OAc]$^-$ were used not only for fingerprinting analysis but for the quantification of each epimer by using multiple-reaction monitoring mode. It was shown good linearity ($r^2{\geq}$ 0.9998) over the wide range of all analytes; intra- and inter-day precisions (RSD, %) were within 9.14% and the accuracy ranged from 84.3 to 115.1%. The analytical results of 40 drug samples, combined with multivariate statistical analyses - principal component analysis (PCA) and hierarchical cluster analysis (HCA) - clearly demonstrated the classification of the test samples according to their botanical origins. This method would provide a practical strategy for assessing the authenticity or quality of the herbal drug.

• 보건교육건강증진학회지
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• 제21권2호
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• pp.147-165
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• 2004

Injury is a leading cause of death in the children and adolescent populations. In particular, more than 80％ of unintentional injury was related to risk-taking behaviors involved in diverse accidents around school and home. Therefore, educational approaches should be provided for children and adolescent populations, and schools are the essential and appropriate sites to conduct safety education. This study was conducted to identify injury prevalence and safety education at schools among middle and high school students in Korea. About 1,034 middle and high students in 28 schools participated in a self-administered survey. The target schools were selected from the stratified random sampling method throughout schools of seven metropolitan cities in Korea. The questionnaires were delivered to the vice-principals by ground mailing service and the vice-principals administered survey data collection. The questionnaire asked about safety education provided in schools, injury experience in the last year, needs for injury prevention class in school, and demographics. All survey responses were entered into SPSS worksheet. Multivariate analysis of variance (MANOVA) and descriptive discriminant analysis (DDA) were used in statistical analysis with SPSS software 11.1. Multivariate analysis of variance was conducted as a preliminary analysis of DDA. According to the result of multivariate analysis of variance, gender (man), grade (poor), living with both parents, and displaying injury prevention messages on school news board were significantly different between the injured student group and the uninjured student group (p＝ .00). These four factors also had significant effects on students' injury experience in DDA, although correlation of the four factors with injury experience was weak overall based on their canonical function coefficients. All structure coefficients of the four factors were greater than .30, which means the four factors have discriminant effects on injury prevalence. The sizes of the discriminant effects, in order, were largly from gender, grade, living with both parents, and safety message display on school news boards.

• 한국물환경학회지
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• 제35권1호
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• pp.19-27
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• 2019

The purpose of this study is to evaluate the water quality and phytoplankton community in Bukhan River which account for 44.4 % of the total inflow into Lake Paldang, using multivariate statistical techniques (i.e., correlation analysis, principal component analysis (PCA)/factor analysis (FA)). Water samples were collected from March to November 2015 and the following parameters measured; water temperature, pH, DO, EC, SS, BOD, Chl-a, COD, TN, $NO_3-N$, $NH_3-N$, TP, DTP, $PO_4-P$, and phytoplankton community. The water quality of the main stream and the tributaries were not significantly different apart from the relatively high concentration of BOD, COD and nutrients recorded in MH. The highest cell density of Stephanodiscus hantzschii and Merismopedia glauca dominated phytoplankton was observed in PD. Based on the correlation analysis, total phytoplankton and cyanophyceae were highly correlated with BOD, COD and nutrients. PCA/FA resulted in four main factors accounting for 82.240 % of the total variance in the water quality dataset. The group of component 1 (TN, DTN, DO, $NO_3-N$, water temperature) and component 2 ($PO_4-P$, T-P, DTP, SS) were classified as nutrient element factor whereas component 3 (Chl-a, COD, BOD, $NH_3-N$, pH) was related to organic substances. Hence, the identification of the main potential environmental pollution factors in Bukhan River will help policy makers make better and more informed decisions on how to improve the water quality.

• 생약학회지
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• 제3권4호
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• pp.187-197
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• 1972

In spite of the fact that the system of oriental medicine still remains in the realm of 'unproven-method of treatment', no one can deny that the oriental medicine is a rich source of idea and motivation for the discovery of new drug from natural sources. However, non-scientific, mystic hypothetical system of oriental medicine refuses to be revealed scientifically. For the purpose of drawing useful parameters for inductive reasoning of the system, a new approach which comprises statistical analyses of prescription was attempted in this study. One hundred and thirty two ginseng-compounds prescription in 'Bang-Yak-Hap-Pyon', one of the most popular formularies of oriental medicine in Korea, were analysed by multivariate analysis technique. The results revealed ginseng from many points of view, e.g., therapeutic indications, dose, and compatibility, etc. Among these, the most striking coincidence with scientific achievements of modern pharmacology, is the fact that the oriental medicine has characterized ginseng already from remote ancient times as neither a specific curative nor an aphrodisiac, but a non-specific adaptogenic drug for general infirmity.