• Journal of the Korean Data and Information Science Society
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• v.18 no.4
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• pp.1135-1143
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• 2007

The singular value decomposition and the spectral decomposition are the useful methods in the area of matrix computation for multivariate techniques such as principal component analysis and multidimensional scaling. These techniques aim to find a simpler geometric structure for the data points. The singular value decomposition and the spectral decomposition are the methods being used in these techniques for this purpose. In this paper, the singular value decomposition and the spectral decomposition are compared.

• Communications for Statistical Applications and Methods
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• v.11 no.3
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• pp.465-474
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• 2004

Data visualization is the automation process and the discovery process to data sets in an effort to discover underlying information from the data. It provides rich visual depictions of the data. It has distinct advantages over traditional data analysis techniques such as exploring the structure of large scale data set both in the sense of number of observations and the number of variables by allowing great interaction with the data and end-user. We discuss the principles of data visualization and evaluate the characteristics of various tools of visualization according to these principles.

• Journal of the Korean Association of Geographic Information Studies
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• v.6 no.4
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• pp.99-108
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• 2003

In early year 2003, the previous Urban Planning Law and National Land Use Management Law were abolished and integrated into the Law regarding National Land Planning and Land Use Management. Accordingly, previous Urban Planning Information System is reformed into National Land Use Information System. This paper intends to develop indexes supporting decision-making process and to construct theme map using digital map that can be utilized for the National Land Use Information System. As a base for the index development, necessary database(DB) was established by utilizing the socio-economic information of towns and villages in Busan and a layer of public facilities. Based on the DB, multivariate analyses were performed to examine and analyze the spatial structure of Busan. It was then expressed and constructed as a theme map. The facility theme map was also constructed based on a layer of public facilities and the shortest distance between towns and villages.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.6
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• pp.3166-3187
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• 2017

For "generic" multivariate public key cryptography (MPKC) systems, experts believe that the Unbalanced Oil-Vinegar (UOV) scheme is a feasible signature scheme with good efficiency and acceptable security. In this paper, we address two problems that are to find inversion solution of quadratic multivariate equations and find another structure with some random Oil-Oil terms for UOV, then propose a novel signature scheme based on hyper-sphere (HS-Sign for short) which directly answers these two problems. HS-Sign is characterized by its adding Oil-Oil terms and more advantages compared to UOV. On the one side, HS-Sign is based on a new inversion algorithm from hyper-sphere over finite field, and is shown to be a more secure UOV-like scheme. More precisely, according to the security analysis, HS-Sign achieves higher security level, so that it has larger security parameters choice ranges. On the other side, HS-Sign is beneficial from both the key side and computing complexity under the same security level compared to many baseline schemes. To further support our view, we have implemented 5 different attack experiments for the security analysis and we make comparison of our new scheme and the baseline schemes with simulation programs so as to show the efficiencies. The results show that HS-Sign has exponential attack complexity and HS-Sign is competitive with other signature schemes in terms of the length of the message, length of the signature, size of the public key, size of the secret key, signing time and verification time.

• Korean Journal of Health Education and Promotion
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• v.21 no.2
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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.

• Journal of the Korean Society of Safety
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• v.37 no.1
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• pp.20-29
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• 2022

To stem the ever-prevalent occurrence of industrial accidents in the construction industry, which is emerging as a social problem, efforts must be invested by various stakeholders. Specifically, among stakeholders, the orderer is at the top of a project's decision-making structure. Therefore, the orderer's awareness of safety and health directly affects the process of securing the safety of the overall construction site. In this light, the present study aims to identify differences in the perceptions of each stakeholder regarding the obligatory safety and health measures for clients that have recently been introduced. In addition, it suggests specific implementation plans in the Korean context. The data used for analysis were collected through a survey targeting stakeholders such as orderers, safety managers, and site managers, and the collected data were quantitatively reviewed by using multivariate analysis methods such as analysis of variance. As a result of the analysis, the introduction of safety and health obligations for the owner was found to be necessary, and the designation and operation of safety and health experts as an action plan was deemed reasonable. The authors expect that the results of this study can be used as basic data for revising the related regulations in Korea. Moreover, as a further study, a review of the effectiveness after improving regulations would contribute strongly to the domain.

• Korean Institute of Interior Design Journal
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• no.25
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• pp.245-252
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• 2000

Since the twentieth century, common exhibitions have experienced display replacements and apace alterations. As a result, not only the visual space background of the spectators but the structure systems and positions of the construction space have also been changed. With regards to common zones of the exhibition space, appropriate harmonization of spectators space, aisle space, and media space are closely related the effectiveness and propriety of display arrangement. A number of preceeding researches suggest exhibition first, construction next, regarding the order of the construction and exhibition of the museums and art galleries. However, a majority of the exhibition hall constructions in Korea have not been carried away based on these models. Thus, disharmony of constructions and exhibition space structures have caused numerous problems. The purpose of this research is to seek the countermeasures that can be used in the stage of planning for the museum constructions and exhibition space by suggesting, based on the above mentioned points, the development of the indicators and analyzing methods to understand the structural attributes of the common exhibition space through space syntax method and multivariate analysis.

• Korean Journal of Plant Taxonomy
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• v.41 no.3
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• pp.223-229
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• 2011

The taxonomy of the Isodon excisus complex has been ambiguous and problematic because the morphological characters, especially characters related to the leaf distinguishing subgroups of the complex in the original descriptions, are variable. To elucidate the taxonomic structure of the I. excisus complex in Korea, 34 characters were measured from 70 OTUs representing different locations and analyzed by principal component analysis (PCA). The analysis showed that principle component axis 1, 2, 3 (PC1, PC2, PC3) represents 52.0% of the total variance and characters showing high loading values for PC1 were leaf shape, density of non-glandular hairs on the lower surface of the leaf, and characters related to the teeth of the leaf. The length of apical tooth and the angle between two widest points of the leaf were highly correlated to PC2 and PC3, respectively. Three-dimensional scatter plotting of OTUs for PC1, PC2, and PC3 axis showed that the areas of previously recognized three subgroups of I. excisus completely overlapped. Our result supported that just one taxon, I. excisus var. excisus, should be recognized in the complex at the variety level.

• Communications for Statistical Applications and Methods
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• v.28 no.1
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• pp.59-79
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• 2021

Value at Risk (VaR) is one of the most common risk management tools in finance. Since a portfolio of several assets, rather than one asset portfolio, is advantageous in the risk diversification for investment, VaR for a portfolio of two or more assets is often used. In such cases, multivariate distributions of asset returns are considered to calculate VaR of the corresponding portfolio. Copulas are one way of generating a multivariate distribution by identifying the dependence structure of asset returns while allowing many different marginal distributions. However, they are used mainly for bivariate distributions and are not widely used in modeling joint distributions for many variables in finance. In this study, we would like to examine the performance of various copulas for high dimensional data and several different dependence structures. This paper compares copulas such as elliptical, vine, and hierarchical copulas in computing the VaR of portfolios to find appropriate copula functions in various dependence structures among asset return distributions. In the simulation studies under various dependence structures and real data analysis, the hierarchical Clayton copula shows the best performance in the VaR calculation using four assets. For marginal distributions of single asset returns, normal inverse Gaussian distribution was used to model asset return distributions, which are generally high-peaked and heavy-tailed.

• Wind and Structures
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• v.32 no.3
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• pp.193-204
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• 2021

The estimation of the extreme wind load (effect) under a mean recurrence interval (MRI) is an important task in the wind-resistant design for the structure. It can be predicted by either first-order method or full-order method, depending on the accuracy and complexity requirement. Although the first-order method with the consideration of wind directionality has been proposed, less work has been done on the full-order method, especially with the wind directionality. In this study, the full-order method considering the wind directionality is proposed based on multivariate joint probability distribution. Meanwhile, considering two wind directions, the difference of the corresponding results based on the first-order method and full-order method is analyzed. Finally, based on the measured wind speed data, the discrepancy between these two methods is investigated. Results show that the difference between two approaches is not obvious under larger MRIs while the underestimation caused by the first-order method can be larger than 15% under smaller MRIs. Overall, the first-order method is sufficient to estimate the extreme wind load (effect).