• Journal of the Korean Data and Information Science Society
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• v.7 no.2
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• pp.295-299
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• 1996

In this paper, optimal change times are determined for fully three-step stress accelerated life tests, which minimize the asymptotic variance for maximum likelihood estimator of logarithm of the failure rate at the usual condition and exponential distribution is given for life time data.

• Journal of the Korean Data and Information Science Society
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• v.6 no.2
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• pp.65-76
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• 1995

The importance of left truncated and right censoring cases has considered for better information in medical follow-up and engineering life testing studies. We propose some estimation procedure for the mean residual life function with consistency and asymptotic normality on the left truncated and right censoring model. And then, the comparision with Kaplan-Meier estimator ignoring the left truncated effect and the small sample properities are investigated by asymptotic biases and M.S.E.'s thresh Monte Carlo study.

• Journal of the Korean Data and Information Science Society
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• v.6 no.2
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• pp.77-83
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• 1995

The inferences on a series system under the usual condition using data from constant stress partially accelerated life tests and type I censoring is studied. Two optimal designs to determine the sample proportion allocated each stress level model are also presented, which minimize the sum of the generalized asymptotic variances of maximum likelihood estimators of the failure rate and the acceleration factors and the sum of the asymptotic variances of maximum likelihood estimators of the acceleration factors for each component. Each component of a system is assumed to follow an exponenial distribution.

• Journal of the Korean Data and Information Science Society
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• v.8 no.1
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• pp.99-109
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• 1997

The estimation procedure of mean residual life function has been placed an important role in the study of survival analysis. In this paper, the product limit estimator on left truncated and right censoring model is proposed with asymptotic properties. Also, the small sample properties are investigated through the Monte Carlo study and the proposed product limit type estimator is compared with ordinary Kaplan-Meier type estimator.

• Journal of the Korean Data and Information Science Society
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• v.15 no.4
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• pp.935-943
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• 2004

Most of the accelerated life tests deal with tests that use only one accelerating variable and no other explanatory variables. Frequently, however, there is a test to use more than one accelerating or other experimental variables, such as, for examples, a test of capacitors at higher than usual conditions of temperature and voltage, a test of circuit boards at higher than usual conditions of temperature, humidity and voltage. A accelerated life test is extended to M-level stress accelerated life test with k-stress variables. The optimal design for Weibull distribution is studied with k-stress variables.

• Proceedings of the Korean Society of Coastal and Ocean Engineers Conference
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• 1992.08a
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• pp.23-27
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• 1992

대형선박이 접안하여 하역작업을 수행하는 동해안의 산업항중 포항신항에서는 과거의 연구나 한국해양연구소의 현장관측(건설부, 1987; 강 등, 1989)을 통하여 다양한 주기의 부진동이 존재함이 밝혀졌으며, 검조소가 없는 동해항의 인근에 위치한 묵호항의 검조기록을 검토한 결과 10분대의 장주기 부진동이 존재하는 것으로 나타났다.(중략)

• The Pure and Applied Mathematics
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• v.8 no.1
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• pp.25-32
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• 2001

Let A be a nonnegative matrix of size $n \times n$. A is said to be nearly convertible if A(i│j) is convertible for all integers i, j$\in${1,2,…, n} where A(i│j) denote the submatrix obtained from A by deleting the i-th row and the j-th col-umn. We investigate some properties of nearly convertible matrices and existence of (maximal)nearly convertible matrices of size n is proved for any integers $n(\geq 3)$.

• Proceedings of the Korean Society of Environment and Ecology Conference
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• 2006.10a
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• pp.254-256
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• 2006

• Proceedings of the SAREK Conference
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• 2003.07a
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• pp.195-195
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• 2003

• Proceedings of the SAREK Conference
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• 2003.07a
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• pp.81-81
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• 2003