• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.2
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• pp.164-171
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• 2008

This paper proposes the planning method for placement of capacitors in a distribution system. The main objectives in the planning for capacitor allocation are the reduction of installation costs and electric power loss. In the proposed method, the life time of each device is considered in calculating installation costs, and the optimal operation status of devices is found by genetic algorithm. Then, the optimal numbers and locations are determined based on the optimal operation status. Simulation results in the 69-bus distribution system show that the proposed method performs better than conventional methods.

• Journal of Korea Society of Digital Industry and Information Management
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• v.7 no.2
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• pp.1-8
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• 2011

In this study, software products developed in the course of testing, software managers in the process of testing software test and test tools for effective learning effects perspective has been studied using the NHPP software. The finite failure non-homogeneous Poisson process models presented and the life distribution applied extreme distribution which used to find the minimum (or the maximum) of a number of samples of various distributions. Software error detection techniques known in advance, but influencing factors for considering the errors found automatically and learning factors, by prior experience, to find precisely the error factor setting up the testing manager are presented comparing the problem. As a result, the learning factor is greater than automatic error that is generally efficient model could be confirmed. This paper, a numerical example of applying using time between failures and parameter estimation using maximum likelihood estimation method, after the efficiency of the data through trend analysis model selection were efficient using the mean square error.

• Journal of Korean Society for Quality Management
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• v.25 no.1
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• pp.173-181
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• 1997

A modified periodic inspection policy is examined. It is troublesome to know the life distribution and burdensome to compute an optimum planned inspection time numerically as well. A nonparametric a, pp.oximation is used so that equations for the optimum inspection time are expressed as closed forms. To show that the a, pp.oximation can be used in practice, simulations are conducted in the case of Weibull failure times.

• Journal of the Korea Safety Management & Science
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• v.15 no.1
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• pp.109-120
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• 2013

As information-oriented industry has been developed and electronic devices has come to be smaller, lighter, multifunctional, and high speed, the components used to the devices need to be much high density and should have find pattern due to high integration. Also, diverse reliability problems happen as user environment is getting harsher. For this reasons, establishing and securing products and components reliability comes to key factor in company's competitiveness. It makes accelerated test important to check product reliability in fast way. Out of fine pattern failure modes, failure of Electrochemical Migration(ECM) is kind of degradation of insulation resistance by electro-chemical reaction, which it comes to be accelerated by biased voltage in high temperature and high humidity environment. In this thesis, the accelerated life test for failure caused by ECM on fine pattern substrate, $20/20{\mu}m$ pattern width/space applied by Semi Additive Process, was performed, and through this test, the investigation of failure mechanism and the life-time prediction evaluation under actual user environment was implemented. The result of accelerated test has been compared and estimated with life distribution and life stress relatively by using Minitab software and its acceleration rate was also tested. Through estimated weibull distribution, B10 life has been estimated under 95% confidence level of failure data happened in each test conditions. And the life in actual usage environment has been predicted by using generalized Eyring model considering temperature and humidity by developing Arrhenius reaction rate theory, and acceleration factors by test conditions have been calculated.

• Progress in Medical Physics
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• v.28 no.2
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• pp.39-44
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• 2017

This study aims to analyze dose distribution and treatment time of endobronchial brachytherapy (EBBT) by changing the position step size of the dwell position. A solid water phantom and an intraluminal catheter were used in the treatment plan. The treatment plans were generated for 3, 5, 7, and 10 cm treatment lengths, respectively. For each treatment length, the source position step sizes were set as 2.5, 5, and 10 mm. Three reference points were set 1 cm away from the central axis of the catheter, along the axis, for uniform dose distribution. Volumetric dose distribution was calculated to evaluate the dosimetric effect. The total radiation delivery time and total dwell time were estimated for treatment efficiency, which were increased with position step sizes. At half-life time, the differences between the position step sizes in the total radiation delivery time were 18.1, 15.4, 18.0, and 24.0 s for 3, 5, 7, and 10 cm treatment lengths, respectively. The dose distributions were more homogenous by increasing the position step sizes. The dose difference of the reference point was less than 10%. In brachytherapy, this difference can be negligible. For EBBT, the treatment time is the key factor while considering the patient status. To reduce the total treatment time, EBBT can be performed with 2.5 mm position step size.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.59 no.4
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• pp.467-472
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• 2010

In this study, an analysis of the used RCD's condition is conducted to assess the effect on environment of installation area, terms of use, corrosion, contamination etc. According to KS C 4613, the used RCDs were tested to get date which is the RCD's life time. And then, the date is analysed using Minitab which is a statistical program for reliability analysis. As a result, The RCD's MTTF for the all samples is $12.7{\pm}0.23$ years. and the MTTF of RCDs which are used indoor area is $12.9{\pm}0.34$ years, the MTTF of RCDs which are used outdoor area is $11.9{\pm}0.30$ years. Futhermore, the MTTF of RCDs which are used in dry area is a $13.1{\pm}0.26$ years, the MTTF of RCDs which are used in dust area is $13.0{\pm}0.57$ years, the MTTF of RCDs which are used in moisture area is $8.4{\pm}0.77$ years.

• Journal of Information Technology Applications and Management
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• v.27 no.3
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• pp.69-75
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• 2020

In this paper, we applied the shape parameters of the exponentialized exponential life distribution widely used in the field of software reliability, and compared the reliability properties of the software using the non-homogeneous Poisson process in finite failure. In addition, the average value function is also a non-decreasing form. In the case of the larger the shape parameter, the smaller the estimated error in predicting the predicted value in comparison with the true value, so it can be regarded as an efficient model in terms of relative accuracy. Also, in the larger the shape parameter, the larger the estimated value of the coefficient of determination, which can be regarded as an efficient model in terms of suitability. So. the larger the shape parameter model can be regarded as an efficient model in terms of goodness-of-fit. In the form of the reliability function, it gradually appears as a non-increasing pattern and the higher the shape parameter, the lower it is as the mission time elapses. Through this study, software operators can use the pattern of mean square error, mean value, and hazard function as a basic guideline for exploring software failures.

• Journal of Life Science
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• v.16 no.7 s.80
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• pp.1119-1122
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• 2006

Ten species of Lycoris was selected for establishment of phylogenetic relationships using random amplified polymorphic DNA (RAPD) analysis, the native distribution and flowering characterestics. On the basis of the dendrogram constructed with the similarity coefficients, 10 Lycoris species were divided into two clusters. L. sprengeri and L. incannta were showed very high similarity in the RAPD analysis, same flowering time and flower color as pink. The leaf of L. squamigera. L. sanguinea, L. koreana, L. sprengeri and L. incanata emergenced in spring. The L. squamigera and L. sanguinea were showed high similarity in same cluster. Also L. koreana, L. sprengeri and L. incanata were showed high similarity in same cluster. The flower of L. radiata, L. radiata var pumila, L. albiflora and L. traubii was spider. These species was showed very low similarity in another Lycoris species.

• Journal of Distribution Science
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• v.14 no.10
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• pp.165-178
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• 2016

Purpose - This study aims to empirically verify the impact of media richness, social presence, and prior life satisfaction on various continual usage or withdrawal behaviors of SNS users via both a positive path of satisfaction and a negative path of relative deprivation. By identifying these causal paths, we observe dynamic interactions of SNS user psychology in a balanced view, and provide some implications about design principles for SNS providers. Research design, data, and methodology - We developed 16 hypothesis based on media richness theory, social presence theory, social comparison theory, the literature about relative deprivation, and the literature about the various reactions of IS users. The rich SNS media, social presence recognition among peer SNS users, and prior life satisfaction could generate positive experience, attitude, and virtuous behavioral intentions among SNS users. At the same time, rich media, low social presence, and low prior life satisfaction could generate relative deprivation and could increase withdrawal behavioral intentions such as refusal to provide information, misrepresentation of information, and removal of uploaded information in SNS. Scenario surveys were conducted to collect data from potential SNS users. Data from 357 surveys were collected and analyzed through a PLS algorithm to test the hypotheses. Results - Media richness, social presence, and prior life satisfaction could significantly increase perceived enjoyment, satisfaction, and behavioral intention of continual usage and knowledge sharing. They also could significantly decrease refusal and misrepresentation intention. Relative deprivation is significantly decreased only by prior life satisfaction. Relative deprivation could not significantly decrease satisfaction, but it could significantly increase misrepresentation and removal intention, which could be regarded as information distortion intention. Conclusions - SNS providers should focus on developing rich media and social presence support because these two variables could impact the positive experiences of SNS users. Moreover, the positive experiences could heavily influence SNS user behavior. Some management is needed to prevent relative deprivation and its consequences of misrepresentation and removal intention. SNS providers should prevent SNS users from excessive image misrepresentation and removal as this information distortion could be the source of relative deprivation.

• Korean Journal of Ichthyology
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• v.24 no.1
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• pp.56-61
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• 2012

The distribution status and population size of the endangered species, $Cobitis$ $choii$, were investigated in the Guem River, Korea. From 1984~2004, this species occurred at 20 survey stations; however, their numbers have but rapidly decreased in recent years (2006~2011), during which time they were only observed at six stations. The area of their habitat is narrow and occurs in primarily downstream, sandy zones. Using the mark-recapture method, populations were estimated at 9,106 and 34,717 individuals for the main habitats of Baekgok and Ji Stream, respectively.