• Communications for Statistical Applications and Methods
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• v.11 no.1
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• pp.49-58
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• 2004

In this talk we proposed an asymptotic test for dimensionality in the latent variable model for probabilistic principal component analysis with missing values at random. Proposed algorithm is a sequential likelihood ratio test for an appropriate Normal latent variable model for the principal component analysis. Modified EM-algorithm is used to find MLE for the model parameters. Results from simulations and real data sets give us promising evidences that the proposed method is useful in finding necessary number of components in the principal component analysis with missing values at random.

• Journal of Preventive Medicine and Public Health
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• v.15 no.1
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• pp.219-228
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• 1982

This study aimed at assessing the industrial workers' mental health status and identifing the relationship between mental health status and socio-demographic variables. We administered psychiatric self report rating scale (SCL-90)to 622 manual workers and 191 office workers in a textile .industry. The study began on 1 November, 1981 and lasted for 30 days The results were as follow: 1. Scores of symptom dimension were higher in female rather than male, younger than older, lower income group than higher one, lower educated group than higher one, manual workers than office workers and unmarried group than married one respectively. 2. The result of dimension scores of total samples showed that the score of Obsessive-compulsive scale was highest. The rest symptom dimension showed the order as follows: Interpersonal sensitivity, Depression, Hostility, Anxiety, Paranoid ideation, Somatization, Psychoticism and Phobic anxiety. 3. In order to identify the partial contribution of each socio-demographic variables on the mental health, multiple regression method was applied, and the result was as follows. 1) Sex was the most important one to explain the Somatization, Phobic-anxiety and Psychoticism scales among the 7 variables in the multiple regression equation. 2) Economic status was the most important variable to explein the Obsessive-compulsive, Depression and Hostility scales. 3) Marital status was the most important variable to explain the Interpersonal-sensitivity and Paranoid ideation scales.

• The Korean Journal of Applied Statistics
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• v.23 no.5
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• pp.813-822
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• 2010

We investigate a possible achievement in dimension reduction of time series via partially quantified principal component. Partial quantification technique allows us in modeling to accommodate artificial variable(s) of practical importance which is defined subjectively by the data analyst. Suggested procedures are described and in turn illustrated in detail by analyzing monthly unemployment rates in Korea.

• Journal of Industrial Convergence
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• v.3 no.1
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• pp.79-100
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• 2005

Considering the above points, this study has been conducted to find out the effects brought by perceived organizational justice towards organizational citizenship behavior, with focus on multi-dimension and multi-class nature of trust. With this objective, I researched the following. First, which type gives larger effect to organizational citizenship behavior, the type of distributive justice (that is lower dimension of organizational justice) or that of procedural justice. Second, what effects are given to the 5 types of trust, by distributive justice and procedural justice. Also, what effects are given to organizational citizenship behavior by the 5 types of trust. Third, which type of justice gives larger effect to organizational citizenship behavior when trust is served as a medium. Fourth, which items should be dealt in priority to lead members of organization towards a desirable direction. The research for this purpose was conducted on the basis of comprehensive analysis of variable including. socio-population variable.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.26 no.1
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• pp.18-26
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• 2002

With the introduction of Fractal notation, various fields of engineering adopted fractal notation to express characteristics of geometry involved and one of the most frequently applied areas was turbulence. With research on turbulence regarding the surface as fractal geometry, attempts to analyze turbulent premised flame as fractal geometry also attracted attention as a tool for modeling, for the flame surface can be viewed as fractal geometry. Experiments focused on disclosure of flame characteristics by measuring fractal parameters were done by researchers. But robust principle or theory can't be extracted. Only reported modeling efforts using fractal dimension is flame speed model by Gouldin. This model gives good predictions of flame speed in unstrained case but not in highly strained flame condition. In this research, approaches regarding fractal dimension of flame as one representative value is pointed out as a reason for the absence of robust model. And as an extort to establish robust modeling, Presents methods treating fractal dimension as statistical variable. From this approach flame characteristics reported by experiments such as Da effect on flame structure can be seen quantitatively and shows possibility of flame modeling using fractal parameters with statistical method. From this result more quantitative model can be derived.

• The Journal of Asian Finance, Economics and Business
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• v.8 no.3
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• pp.595-604
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• 2021

This research aimed to explore the relationship between the challenge and enjoyment dimensions of intrinsic motivation and employee creativity at an individual level. Besides, the study focused on investigating the moderating role of empowering leadership in promoting employee creativity at work. In particular, in the context of Vietnam's electricity industry, the power generation stage faces significant challenges, forcing to innovate and restructure strongly to respond flexibly to the requirements of the electricity market development in Vietnam as well as gradually integrate with other countries in Southeast Asia. The authors used structural equations modeling (SEM) combined with Hayes' moderator variable analysis method (2017) based on primary data. The data included 550 questionnaires from technicians, engineers, and experts directly involved in the operation and production of 36 power generation businesses Vietnam. The results showed the relationship between the enjoyment dimension of intrinsic motivation and employee creativity is not statistically significant, which partly explains the instability of the link between intrinsic motivation and employee creativity. Meanwhile, the challenge dimension is positively associated with employee creativity, but this relationship is more robust in empowering leadership. The study also indicated the challenge dimension of intrinsic motivation is an important predictor of employee creativity.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• v.6 no.1
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• pp.91-107
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• 2002

This paper presents two new self-scaling variable-metric algorithms. The first is based on a known two-parameter family of rank-two updating formulae, the second employs an initial scaling of the estimated inverse Hessian which modifies the first self-scaling algorithm. The algorithms are compared with similar published algorithms, notably those due to Oren, Shanno and Phua, Biggs and with BFGS (the best known quasi-Newton method). The best of these new and published algorithms are also modified to employ inexact line searches with marginal effect. The new algorithms are superior, especially as the problem dimension increases.

• Communications for Statistical Applications and Methods
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• v.16 no.4
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• pp.707-711
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• 2009

We propose new cointegration tests using signs of the regressors as instrumental variable. Our tests have the asymptotic standard normal distribution and are free from the dimension of regressors under the null hypothesis of no cointegration. A Monte-Carlo simulation shows that the proposed tests have a stable size and an improved power. Particulary, the tests have better power for small numbers of observations.

• Proceedings of the Korea Concrete Institute Conference
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• 2003.05a
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• pp.555-560
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• 2003

Fatigue strength of concrete is ususlly presented by the Wohler Curve. But, new dimension T(time) from the view point of cyclic creep concept should be considerd. This paper presented four variable F-N-T-R relationship, this four variable relationship simultaneously accounts for the time effect and the effect of load rate. And analytical models are presented to predict fatigue strength of R/C beam strengthened with steel plate and carbon fiber sheet. Also, the correlation between the ratio of stress and the fatigue life was investigated.

• Journal of the Korean Data and Information Science Society
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• v.15 no.3
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• pp.605-616
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• 2004

In this paper we consider the proportional hazard models for survival analysis in the microarray data. For a given vector of response values and gene expressions (covariates), we address the issue of how to reduce the dimension by selecting the significant genes. In our approach, rather than fixing the number of selected genes, we will assign a prior distribution to this number. To implement our methodology, we use a Markov Chain Monte Carlo (MCMC) method.