• Proceedings of the Korean Society for Quality Management Conference
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• 1998.11a
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• pp.544-555
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• 1998

Although the bimodal mixed weibull distribution is used to developing burn-in model widely, the failure times for a component or a system is often truncated at some time, T, due to the obsolescence in the electronics industry. In this paper, we will determine minimum total cost and burn-in time by using the bimodal mixed weibull distribution and the truncated bimodal mixed weibull distribution under the free warranty policy. The results of this study are summarized as follows. First, when products or system is not repairable, the width of the change of burn-in time can be larger by ${\beta}_1,\;{\beta}_2$ Second, if burn-in time become longer, it will be impossible to consider the bum-in in a long time, and in this case, the burn-in time should be shorten by the acceleration burn-in. Third, in case that opportunity loss cost or repair cost is exceed the warranty cost, or the total cost of considering burn-in is larger than that of not considering burn-in, it is not existed burn-in time which makes total cost to minimize. Forth, the shorter life-cycle of product, the more burn-in times will be decreased and the cost in considering burn-in will be increased

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.40 no.3
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• pp.99-108
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• 2003

This paper is concerned with the problem of designing a guaranteed cost state feedback controller for singular systems with time-varying delays. The sufficient condition for the existence of guaranteed cost controller, the controller design method, and the optimization problem to get the upper bound of guaranteed cost function are proposed by LMI(linear matrix inequality), singular value decomposition, Schur complements, and change of variables. Since the obtained sufficient conditions can be changed to LMI form, all solutions including controller gain and the upper bound of guaranteed cost function can be obtained simultaneously. Moreover, the proposed controller design method can be extended to the problem of robust guaranteed cost controller design method for singular systems with parameter uncertainties and time-varying delays. The validity of the proposed design algorithm is investigated through a numerical example.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.9 no.6
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• pp.566-572
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• 2016

Software Reliability implemented in software development is one of the most important issues. In finite failure NHPP software reliability models for software failure analysis, the hazard function that means a failure rate may have constant independently for failure time, non-increasing or non-decreasing pattern. In this study, software development cost analysis considering the variable shape parameter of Erlang distribution as the failure life distribution in the software product testing process was studied. The software failure model was applied finite failure Non-Homogeneous Poisson Procedure and the parameters approximation using maximum likelihood estimation was accompanied. Thus, this paper was presented comparative analysis by applying a software failure time data to the software, considering the shape parameter of Erlang distribution for development cost model analysis. When compared to the cost curve in accordance with the shape parameter, the model of smaller shape can be seen that the optimal software release time delay and more cost. Through this study, it is thought that it can serve as a preliminary information which can basically help the software developers to search for development cost according to software shape parameters.

• Journal of The Korean Society of Integrative Medicine
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• v.4 no.3
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• pp.39-47
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• 2016

PURPOSE : This study attempts to find the effects of water perturbation exercise performed on stroke patients in their physiological cost index and gait ability tests. METHOD : The subjects were 30 stroke patients, water perturbation exercise group was performed 3 day per week, for 40 minutes a day, for a period of eight weeks. The physiological cost index and gait of all subjects were assessed by using the polar, 6 Minute Walk Test (6MWT), and 10 meter Walk Test(10mWT) at pre training and post training. Paired t-test was used to analyze change before and after intervention in group. Pearson's correlation was used to analyze correlation of all variables. RESULT : Water perturbation exercise group showed increased physiological cost index. Water perturbation exercise increased gait ability, showing a significant difference. Showing the correlation between the relatively high amount between physiological cost index and 6 minutes walking test. CONCLUSION : From the result of the study, we found that water perturbation exercise was effective in improving physiological cost index and gait ability. The patient is considered to be used by itself to involve the treatment and the risk of falling from the lowered state into the treatment method for the intensive treatment of stroke patients to be useful in improving the cardiovascular system and ability to walk. Through underwater training for stroke patients in the future on the basis of this study it is considered to require additional clinical studies on the impact on daily living and quality of life of stroke patients.

• Journal of the Society of Disaster Information
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• v.8 no.4
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• pp.328-335
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• 2012

The resource-based estimating based on standard unit price of construction work was estimated by multiplying the price per standard unit of work on the amount of labor, material, equipment use time. However, limitation of the resource-based estimating way does not adequately reflect the actual transactions prices. On the subject of water tunnel excavation as a new attempt to overcome these limitations, this study analyzed productivity by work type into cutter inspection/ exchange, TBM maintenance, TBM inspection/refueling, subsequent installations, tramcar, operating change, a cave-underground reinforcement / rock reinforcement, safety / meetings and analyzed actual cost estimating and the net advance rate based on this analysis result. Actual cost estimating calculation approach presented in this study can be utilized as a useful tool to predict the actual cost estimating in the TBM water tunnels field.

• Journal of the Korean Home Economics Association
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• v.29 no.3
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• pp.209-226
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• 1991

This study aimed at providing the basic data for the measurement of the attitude for socialization of household work by analysis of the attitude for socialization of houselhold work according to demographic variables, the degree of acceptance for living change. This study was composed of the attitude for the socialization of household work was based on time, quality, cost factor. The results of this study were as follows: 1. The attitude for socialization of household work was influenced by sex, age, marriage, sex $\times$ marriage and the degree of acceptance for living change. 2. The variables which affected the attitude for socialization of household work independently had influence on it in the following order : the degree of acceptance for living change, sex, house type. 3. The result of path analysis had confirmed that sex, age, income marriage, house type variable indirectly influenced the attitude for socialization of household work through the degree of acceptance for living change. Sex, and marriage variable directly influenced on the attitude for socialization of household work. Through the this study. The attitude for socialization of houselhold work was influnced by the degree of acceptance for living change. Change of household work is socialization of household work and right attitude to the socialization fof household work is necessary for satisfaction of variouse needs. for saving of time and money through the socialization of household work.

• Journal of Animal Environmental Science
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• v.21 no.2
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• pp.47-54
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• 2015

Climate change has directly impacted environmentally dependent first industry. The changes of amount and frequency of precipitation have caused unstable drinking water supply for grassland and feed crop, and have changed the variety of grassland and feed crop. Rising temperature has caused heat stress on livestock, which has impacted feed intake and livestock products, and also has threatened to the health of livestock by widening the range of sources of diseases. In order for livestock industry to confront climate change, new technology development for climate change adaptation and measures of greenhouse gas mitigation are essential. Agroforestry is the one of alternative measures to mitigate greenhouse gases and to adapt to climate change. Agroforestry is the way rearing livestock and cultivating plants in forest, which is suitable to Korea where mountain area is over 68%. Feedstock such as maize, soybean, rice, and grass grown by agroforestry would decrease feed cost. Agroforestry will decrease heat stress of livestock during hot weather and will be possible to pasture, which increases livestock welfare.

• Korean Chemical Engineering Research
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• v.59 no.2
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• pp.232-238
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• 2021

The development of a low cost catalyst with high performance and small amount of carbon deposition on catalyst from toluene steam reforming were investigated by using coal ash as a support material. Ni-loaded coal ash catalyst showed similar catalytic activity for toluene steam reforming compared with the Ni/Al2O3. At 800 ℃, the toluene conversion was 77% for Ni/TAL, 68% for Ni/KPU and 78% for Ni/Al2O3. Ni/TAL showed similar toluene conversion to Ni/Al2O3. However, Ni/KPU produced higher hydrogen yield at relatively lower toluene conversion. Ni/KPU catalyst showed a remarkable ability of suppressing the carbon deposition. The difference in coke deposition and hydrogen yield is due to the composition of KPU ash (Ca and Fe) which increase coke resistance and water gas shift reaction. This study suggests that coal ash catalysts have great potential for the application in the steam reforming of biomass tar.

• Journal of the Korean Solar Energy Society
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• v.32 no.6
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• pp.60-67
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• 2012

Government Geothermal Cooling-Heating Projects has made efforts to reduce GHG(Greenhouse Gas) emissions and to manage cost of greenhouse farm households. This study evaluated the economic benefits of heating load rate of change by comparing Geothermal Cooling-Heating System with the existing system(greenhouse diesel heating) in the Government Geothermal Cooling-Heating Projects. Economic analysis results shows that, 1) When installing the Cooling-Heating system according to the ratio of 70% heating load in policy standards, the geothermal cooling-heating system has economic efficiency with greenhouse type or scale independent because the investment cost is recovered within 7 years. And It was more economic efficiency the ratio of 50% heating load than70% heating load. 2) When installing the Cooling-Heating system according to the glass greenhouse of the ratio of 90% heating load, pay period of investment cost is recovered within 5 years. Therefore it is necessary to apply flexible heating sharing according to greenhouse type or scale.

• Journal of Information Technology Applications and Management
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• v.19 no.2
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• pp.217-231
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• 2012

In the past, companies should make enormous facility investment and acquire a right to do business in order to join communication markets, but now they can do business without important facilities, such as communication networks. Such a movement to ease regulations about companies which want to newly join the communication industry is expected not only to change a competition frame of the mobile communication market but also to greatly affect the entire communication industry. Through this study aiming to look into a way to calculate a reasonable wholesale price related to the government's introduction of the Mobile Virtual Network Operator (MVNO) system, I came up with a following result. I applied the operating profit percentage and the ratio of operating gain to cost to the cost plus model and retail minus model, respectively, to calculate the wholesale price and found that when I calculated with the cost plus model applying the operating profit percentage, I could get the highest wholesale price. On the other hand, I got the lowest wholesale price with the retail minus model by applying the operating profit percentage. Division of expenses and calculation of profit percentage are important factors in calculating the wholesale price and such results are expected to help accurate calculation of the MVNO wholesale price.