• Journal of the Korean Society of Manufacturing Process Engineers
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• v.20 no.11
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• pp.108-114
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• 2021

In this study, a multivariate function was applied to the genetic algorithm for D-type lugs currently used in shipyards to closely analyze the behavioral form of weight loss without double plates. An optimal lifting lug structure design without attachments is proposed. MATLAB R2016a was used to design features by applying multivariate functions to genetic algorithms. Furthermore, the design was achieved by deriving the optimal shapes of lugs using genetic algorithms. The shapes of the designed lugs were validated for structural bonding using the structural analysis program ANSYS 2020 R2, and a robust design of lugs with no appendages was developed.

• Journal of Korea Water Resources Association
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• v.51 no.1
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• pp.49-60
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• 2018

The multivariate regional frequency analysis has many advantages such as an adaption of regional parameters and consideration of a correlated structure of the data. The multivariate regional frequency analysis can provide the broader and more detailed information for the hydrological variables. The multivariate regional frequency analysis has not been attempted to model hydrological variables in South Korea yet. Therefore, it is required to investigate the applicability of the multivariate regional frequency analysis in the modeling of the hydrological variables. The current study investigated the applicability of the homogeneous region delineation and their characteristics in bivariate regional frequency analysis of annual maximum rainfall depth-duration data. The K-medoid method was employed as a clustering method. The discordancy and heterogeneous measures were used to assess the appropriateness of the delineation results. According to the results of the clustering analysis, the employed stations could be grouped into five regions. All stations at three of the five regions led to acceptable values of discordancy measures than the threshold. The stations where have short record length led to the large discordancy measures. All grouped regions were identified as a homogeneous region based on heterogeneous measure estimates. It was observed that there are strong cross-correlations among the stations in the same region.

• Journal of the Korean Operations Research and Management Science Society
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• v.33 no.2
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• pp.153-174
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• 2008

There have been two streams of the studies on development structure : conceptual model approach and statistical analysis approach. But In these days, the latter has been becoming the main approach owing to the development of multivariate statistical methods and statistical packages. In this study, we examine methodologies and results of the leading researches related to development structure based on statistical analysis and propose the future research directions. This analysis would be expected to contribute toward the construction of long-range development policies on each country.

• Journal of the Korean Operations Research and Management Science Society
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• v.17 no.2
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• pp.53-90
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• 1992

THis study examines a contingency relationship between task uncertainty and structure of project teams in conjunction with the leader-member communication patterns. Multivariate analyses are used to analyze the data from 63 R & D project teams of research laboratory in a large manufacturing corporation. Major findings for this study can be summarized as follows. First, project teams with an organic structure are found to yield high performance when task uncertainty is high, while project teams with a mechanistic structure achieve high performance when their tasks are relatively certain. Second, patterns of leader-member comunication are significantly associated with both task uncertainty and structural characteristics of project teams. This implies that leaders of project teams communicate with their members in more conslutative manner when their tasks are uncertain or when their team structure exhibits organic characteristics. Finally, task uncertainty playus a significant moderating role in the relationship between consultative communication patterns and performance of project teams. Based upon these findings, this study offers several theoretical, practical, and methodological implications.

• Korean journal of applied entomology
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• v.54 no.4
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• pp.335-343
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• 2015

One of the primary concerns about the environmental risks of genetically modified (GM) crops is that they may have adverse effects on the local arthropod communities. In this study, we investigated whether the arthropod diversity and community structure in fields of GM rice tolerant to protoporphyrinogen oxidase (PPO)-inhibiting herbicides differ from those in non-GM (control) rice fields. The aim of this study was to assess the potential adverse effects of GM rice on the local arthropod communities. During the growing seasons in the study period, we collected arthropods from both fields by using yellow sticky traps and compared the diversity and community structure of arthropods from the two sites. Overall, the GM rice had no significant effect on the diversity of the local arthropod communities. In addition, multivariate analyses (permutational multivariate analysis of variance and nonmetric multidimensional scaling) showed that the structures of arthropod communities were not affected by the rice genotype (GM vs. non-GM), although these comparisons were made using data obtained at different sampling dates.

• The Journal of Korean Society for School & Community Health Education
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• v.20 no.2
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• pp.13-24
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• 2019

Objective: Recently, Korean adolescent has the problems of nutrition unbalance due to bad eating habits. Also, single-parent and step-parent families have consistently increased because of the increase of divorce rates. Adolescent who lives with a single or step family tends to have unhealthy behaviors and habits. The purpose of this study was to analyze relationship between family structure and irregular breakfast among Korean adolescent. Method: We analyzed 60,040 participants from Korean Youth Risk Behavior Web-based Survey 2018. Study variables included family structure and irregular breakfast. Control variables were sex, school, economic status, parent education levels, drinking, smoking and nutrition education. In terms of this study, descriptive, Chi-square and multivariate logistic regression analysis were performed. Results: After adjusting for socio-demographic variables among boys, family structure was associated with irregular breakfast (living with both parents reference group vs living with single-parent : OR 1.250, 95% CI: 1.142, 1.368). Among girls, after adjusting for control variables, family structure was also associated with irregular breakfast (living with both parents reference group vs living with no both parents : OR 1.409, 95% CI: 1.065, 1.865). Conclusion: According to this study, family structure would be a risk factor of adolescent breakfast habit. Nutrition programs for adolescent should consider these factors.

• Smart Structures and Systems
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• v.10 no.2
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• pp.155-179
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• 2012

This paper aims at assessing the seismic performance of Tuned Mass Dampers (TMDs) based on sets of recorded ground motions. For the simplest configuration of a structure-TMD assembly, in a comprehensive study characteristic response quantities are derived and statistically evaluated. Optimal tuning of TMD parameters is discussed and evaluated. The response reduction by application of a TMD is quantified depending on the structural period, inherent damping of the stand-alone structure, and ratio of TMD mass to structural mass. The effect of detuning on the stroke of the TMD and on the structural response is assessed and quantified. It is verified that a TMD damping coefficient larger than the optimal one reduces the peak deflection of the TMD spring significantly, whereas the response reduction of the main structure remains almost unaffected. Analytical relations for quantifying the effect of a TMD are derived and subsequently evaluated. These relations allow the engineer in practice a fast and yet accurate assessment of the TMD performance.

• Communications for Statistical Applications and Methods
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• v.15 no.6
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• pp.969-976
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• 2008

Mixed linear models have been widely used in various correlated data including multivariate survival data. In this paper we extend hierarchical-likelihood(h-likelihood) approach for mixed linear models with right censored data to that for left censored data. We also allow a general random-effect structure and propose the estimation procedure. The proposed method is illustrated using a numerical data set and is also compared with marginal likelihood method.

• Journal of the Korean Statistical Society
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• v.34 no.2
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• pp.109-123
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• 2005

Variogram estimation is an important step of spatial statistics since it determines the kriging weights. Matheron's variogram estimator can be written as a quadratic form of the observed data. In this paper, we extend a skew t distribution to a generalized skew t distribution and moments of the variogram estimator for a generalized skew t distribution are derived in closed forms. After calculating the correlation structure of the variogram estimator, variogram fitting by generalized least squares is discussed.

• Communications for Statistical Applications and Methods
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• v.8 no.3
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• pp.797-803
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• 2001

This paper obtained Bayes prediction density for the spatial linear model with non-informative prior. It showed the results that predictive inferences is completely unaffected by departures from the normality assumption in the direction of the elliptical family and the structure of prediction density is unchanged by more than one additional future observations.