• Animal Systematics, Evolution and Diversity
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• v.28 no.1
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• pp.12-19
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• 2012

A cyclopoid species from several salt marshes and estuaries on the west coast of South Korea were identified as Halicyclops continentalis Ueda and Nagai, 2009, recently described from Ariake Bay at northwestern Kyushu, Japan. Detailed examination on the Korean specimens justifies Ueda and Nagai's proposition that the H. sinensis sensu Tai and Chen, 1979 formerly known from the Chinese coast of the Yellow Sea should be identical to H. continentalis. Furthermore, this report reinforces their assumption on the geographical distribution of H. continentalis, that is, the Ariake Bay population is a continental relict of the East Asia continent. Herein, a redescription of the species is provided on the basis of the Korean specimens, with a comment on the morphological comparison among three populations around the Yellow Sea.

• Journal of the military operations research society of Korea
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• v.9 no.1
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• pp.63-68
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• 1983

The ideal way of eliminating errors in a large scale software system is to test the software with all possible inputs, providing sufficiently large amount of execution time. However, in practice, the test must be performed within given budget and time limits. Therefore, to perform the test under given constraints, we have to properly select inputs and determine the execution time for each selected inputs. This paper studies the distribution of number of errors at a given time as well as the distribution of time required to reduce the number of errors to a certain level. We assumed that error occurrence times are distributed exponentially (not necessarily identical) and the number of errors at the initial stage is known or estimable.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.22 no.2
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• pp.228-234
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• 2013

This study focuses on development of a finite element model for analysis of thermal characteristics of a direct-connection spindle of a machining center by joint simulation of heat transfer and thermal deformation. Two finite element analyses were carried out procedurally for heat transfer, first, to identify temperature distribution of components of the spindle and then for thermal deformation to identify their structural behavior based on the temperature distribution. It was assumed that the heat transfer between a component revolving and the surrounding air is identical to that between a flat plate and the running air on it and the heat transfer is based on a uniform surface heat flux for turbulent flow. The results from the analyses were compared with those from experiments to validate the finite element model.

• Journal of the Korean Society for Precision Engineering
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• v.15 no.4
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• pp.51-57
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• 1998

It is common to assume identical allowable safety factors in static strength defined by mean stress and in fatigue, defined by stress amplitude. Under the load with asymmetrical cycles the safety factor is not the same. In this paper, with the consideration of unequal allowable safety (actors a general method for estimating fatigue reliability of a machine element under a combined state of stress is derived based on the theory proposed by Prof. Kececioglu and a normal distribution. The calculation of fatigue reliability fur limited life is discussed with example.

• Journal of Welding and Joining
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• v.26 no.6
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• pp.92-96
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• 2008

An investigation was performed to predict residual stress redistribution for the crack propagation initially through tensile residual stress field. The analytical method, which is based on Dugdale model by finite element analysis using elastic analysis method considering the superposition principle, was proposed to estimate the redistribution of residual stress caused by crack propagation. The various aspect of distribution of residual stress caused by crack propagation was examined based on the configuration change of specimen. The analysis results show that the aspect of redistribution of residual stress caused by crack propagation depends on the width of the specimen provided that the initial distribution of residual stress is identical.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.18 no.34
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• pp.61-67
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• 1995

Through the model presented in this paper, we study on the depletion of stock taking place due to random loss of items as well as random demand, under the assumption that the distributions of demand are independent of those of loss, and both of them are identical, and that life time distribution of each item is negative exponential. The steady state probability distribution of the stock level assuming instantaneous delivery of order under (s, S) inventory policy. Also we have derived total expected cost expression with loss cost. The results of sensitive analysis show that the effect of loss rate is substantial on the total cost and optimal value of inventory level.

• Journal of Magnetics
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• v.4 no.3
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• pp.80-83
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• 1999

Relations between giant magnetoresistance (GMR) characteristic, magnetic properties and structure were investigated in Cu90Co10 alloy obtained by melt spinning in which GMR was enhanced by appropriate annealing. The structure of the annealed sample is not homogeneous (though the sizes distribution of the majority of Co-particles is not very wide but much larger particles are also present). On the other hand, the GMR characteristics differs from that expected theoretically for identical superparamagnetic particles. It is shown that ther main sources of the observed non-quadratic magnetoresistance dependence on magnetization are differentialted surface to volume ratio of superparamagnetic particles and the ferromagnetic phase contribution to the total magnetization which was calculated applying the new method.

• Journal of Korean Institute of Industrial Engineers
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• v.14 no.2
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• pp.91-97
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• 1988

In accelerated life testing, a relationship is usually assumed between the stress and a parameter of the lifetime distribution. However, the true relationship is not usually known, and therefore, the experimenter may wish to provide protections against the likely departures from the assumed relationship. This paper considers an accelerated life test in which two stress levels are involved, and the lifetime of each test item at a stress level is assumed to have an independent, identical, exponential distribution. For the case where a first order relationship is assumed while the true one is quadratic, a procedure is developed for allocating test items to stress levels such that the bias and/or the variance of the estimated(log-transformed) mean lifetime at the use condition is minimized.

• Communications for Statistical Applications and Methods
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• v.22 no.4
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• pp.377-387
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• 2015

The area under the ROC curve can be represented by both Mann-Whitney and Wilcoxon rank sum statistics. Consider an ROC surface and manifold equal to three dimensions or more. This paper finds that the volume under the ROC surface (VUS) and the hypervolume under the ROC manifold (HUM) could be derived as functions of both conditional Mann-Whitney statistics and conditional Wilcoxon rank sum statistics. The nullhypothesis equal to three distribution functions or more are identical can be tested using VUS and HUM statistics based on the asymptotic large sample theory of Wilcoxon rank sum statistics. Illustrative examples with three and four random samples show that two approaches give the same VUS and $HUM^4$. The equivalence of several distribution functions is also tested with VUS and $HUM^4$ in terms of conditional Wilcoxon rank sum statistics.

• International Journal of Reliability and Applications
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• v.14 no.2
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• pp.97-105
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• 2013

A stress-strength model is formulated for a multi-component system consisting of k identical components. The k components of the system with random strengths ($X_1$, $X_2$, ${\ldots}$, $X_k$) are subjected to one of the r random stresses ($X_{k+1}$, $X_{k+2}$, ${\ldots}$, $X_{k+r}$). The estimation of system reliability based on maximum likelihood estimates (MLEs) and Bayes estimators in k component system are obtained when the system is either parallel or series with the assumption that strengths and stresses follow exponential distribution. A simulation study is conducted to compare MLE and Bayes estimator through the mean squared errors of the estimators.