• Proceedings of the Korean Statistical Society Conference
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• 2002.11a
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• pp.103-108
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• 2002

We consider an estimation of discontinuous variance function in nonparametric heteroscedastic random design regression model. We first propose estimators of a change point and jump size in variance function and then construct an estimator of entire variance function. We examine the rates of convergence of these estimators and give results on their asymptotics. Numerical work reveals that the effectiveness of change point analysis in variance function estimation is quite significant.

• Journal of the Korean Society of Marine Environment & Safety
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• v.2 no.S1
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• pp.53-73
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• 1996

Almost of all the impediments to enchancing ship safety and preventing vessel-source marine pollution arise from the interaction between direct and indirect factors. The direct factors come from human errores and failure in complince with the international convention standards for the operation of vessels. The indirect factors derive from the will and attitudes of the countries taking little responsibilities with appropriate seriousness for policing their fleets. By focusing in these aspects, this paper intends to propose a new international regime to improve the implementation capability of national maritime administration of each member government of IMO(International Maritime Organization).

• Journal of the Korean Statistical Society
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• v.35 no.1
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• pp.1-23
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• 2006

In this paper we consider an estimation of the discontinuous variance function in nonparametric heteroscedastic random design regression model. We first propose estimators of the change point in the variance function and then construct an estimator of the entire variance function. We examine the rates of convergence of these estimators and give results for their asymptotics. Numerical work reveals that using the proposed change point analysis in the variance function estimation is quite effective.

• Journal of Korean Neurosurgical Society
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• v.46 no.4
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• pp.403-408
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• 2009

A case of spinal intraosseous schwannoma (SIS) in the lumbar vertebra is reported. Clinical and radiologic characteristics of 16 reported cases of SIS were reviewed. SIS can be a rare differential diagnosis for intraosseous tumors.

• Journal of the Korean Statistical Society
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• v.33 no.3
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• pp.255-269
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• 2004

This paper develops log-density estimation for directional data. The methodology is to use expansions with respect to spherical harmonics followed by estimating the unknown parameters by maximum likelihood. Minimax rates of convergence in terms of the Kullback-Leibler information divergence are obtained.

• Communications for Statistical Applications and Methods
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• v.10 no.1
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• pp.31-38
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• 2003

A simple method is proposed to detect the number of change points and test the location and size of multiple change points with jump discontinuities in an otherwise smooth regression model. The proposed estimators are based on a local linear regression fit by the comparison of left and right one-side kernel smoother. Our proposed methodology is explained and applied to real data and simulated data.

• Bulletin of the Korean Chemical Society
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• v.29 no.11
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• pp.2303-2304
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• 2008

• Bulletin of the Korean Chemical Society
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• v.23 no.6
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• pp.879-884
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• 2002

A series of novel 1,3-alternate calix[4]-mono-thiacrown and -bis-thiacrowns were synhesized within good yields. The three dimensional 1,3-alternate conformation was confimed by X-ray crystal structure. From the results of two phase extraction and NMR studies on the ligand-metal complex, one can conclude that the calix[4]thiacrown ethers showed the very high selectivity for silver ion over other metal ions by an electrostatic interaction between sulfur atom and silver ion and by a $\pi-metal$ complexation.

• Bulletin of the Korean Chemical Society
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• v.29 no.7
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• pp.1407-1408
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• 2008

• Journal of the Korean Statistical Society
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• v.33 no.1
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• pp.59-78
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• 2004

A regression function in generalized linear model may have a discontinuity/change point at unknown location. In order to estimate the location of the discontinuity point and its jump size, the strategy is to use a nonparametric approach based on one-sided kernel weighted local-likelihood functions. Weak convergences of the proposed estimators are established. The finite-sample performances of the proposed estimators with practical aspects are illustrated by simulated examples.