• Journal of the Korean Solar Energy Society
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• v.31 no.5
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• pp.33-40
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• 2011

In this study, it is quantitatively analyzed for thermal Characteristics of isolation-heat paint which has been supplied to a domestic market through experiments and simulations. In the case of experiment using the container box, it shows 8% decrease on cooling energy consumption in a summer season, but shows increase on heating energy consumption. As a result, the analysis has found increase of energy consumption. As a result of holding simulations with meteorological data of domestic major cities, it shows an increase of energy consumption in domestic condition, and it is hard to expect an energy saving from the isolation-heat paint unless greater air-conditioning load.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2002.05a
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• pp.923-929
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• 2002

We discuss scheduling analysis for a discrete event system with time windows of which firing or holding time delays are subject to random variation within some finite range. To do this, we propose a modified p-lime Petri net, named p+-time Petri net. We develop a condition for which a synchronized transition does not have a dead token, that is, the firing epochs do not violate the time window constraints. We propose a method of computing the feasible range of the token sojourn time at each place based on a time difference graph. We also discuss an application for analyzing wafer residency times within the process chambers for a dual-armed cluster tool for chemical vapor deposition.

• Journal of the Korea Safety Management & Science
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• v.8 no.5
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• pp.139-150
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• 2006

The aim of this study is to establish an efficient distribution planning for a capacitated multi-stage supply chain. We assume that the demand information during planning horizon is given a deterministic form using a certain forecasting method. Under such a condition, we present a cost effective heuristic method for minimizing chain-wide supply chain inventory cost that is the sum of holding and backorder costs by using look-ahead technique. We cope with the capacity restriction constraints through look-ahead technique that considers not only the current demand information but also future demand information. To evaluate performance of the proposed heuristic method, we compared it with the extant research that utilizes echelon stock concept, under various supply chain settings.

• Proceedings of the KIPE Conference
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• 2018.07a
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• pp.210-212
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• 2018

A new switching mode has been proposed to obtain high power factor and low THD in single stage AC-DC converter. The conventional voltage mode control in critical conduction mode distorts input current shape with poor THD in flyback topology. Once TRIAC dimmer is connected, visible flicker in the LED lamp is easily detected due to a lack of TRAIC holding current near the input voltage zero cross. The newly proposed method can shape the input current by providing a desired reference voltage so that low THD is obtained by ideal sinusoidal input current in case of no dimmer connection and flat input current performs good TRIAC dimmer compatibility in phase-cut dimming condition. To confirm the validity of the proposed method, theoretical analysis and experimental result from 8W dimmable LED lighting system are presented.

• The Journal of Fisheries Business Administration
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• v.30 no.2
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• pp.25-37
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• 1999

Some multi echelon inventory systems carry perishable products. The value of these product reduces as the period of time they spend in the system. In this paper We derive the necessary condition to determine optimal quantity, service level for a perishable product. The systems considered consist of two echelons and carry single item. To determine the optimal order quantity, the demand is assumed to be constant, the holding costs may be different in the echelons, and it allows no shortages. I assumed the price of product decreases by negative exponential function. To determine service level, following assumptions used in the model ㆍlead time is constant. ㆍdemand is normal distribution. ㆍthe product starts to perish at the second echelon. Service level is computed for different levels of lead times and for different variance of demands and for different price functions. The experimental results indicate that the service level in cost is a function of service level in demand and perishability of product. Results of the models exhibit that perishability and the age of the product are critical to determine the lot sizing and service level.

• Journal of the Korean Ceramic Society
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• v.27 no.5
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• pp.597-604
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• 1990

In Cubic ZrO2 crystal growth by Skull method, it was examined on effect of homonization on melt as keeping ZrO2(90mol%)-Y2O3(10mol%) melt with 1hr, 2hr, 4hrs, 8hrs, 16hrs, respectively. The optimum homonizing condition in this system was obtained by the examination between quality of grown crystals and soaking time of melt. It was obtained that the lower quality crystal could be produced in the longer holding melt than the optimum soaking time of melt in spite of the supposedly well homonized state, because the melt stability is sensibly dependent on the convective state of melt in skull method (cold crucible process).

• Radiation Oncology Journal
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• v.9 no.2
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• pp.361-367
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• 1991

This paper on the status of radiotherapy machine and related facilities, clinical activities and radiation safety management is based on the statistical data which collected through the questionaire sent to a total number of 37 hospitals holding the Department of Therapeutic Radiology in Korea. It is true that the quality of instruments installed in the hospitals equal to that of the instrument in the industrialized conuntries' hospitals. But the clinical specialists and physicists who can utilize such instruments fall short of the required number, which might be a main factor in hindering the development of therapeutic radiology of Korea. According to the nation-wide cancer statistics, we can estimate the number of annual cancer patients as 45,000 to 50,000. As a result, probably around 25,000 should receive radiation therapy. It is expected that in the future the number of cancer patients to whom radiation therapy should be applied will become twice as much as that of the cancer patients in 1990. Given such a condition, the problem facing the Korean Society of Therapeutic Radiology now is to increase the number of medical doctors and physicists.

• Journal of Welding and Joining
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• v.5 no.3
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• pp.28-37
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• 1987

To clarify the debonding phenomena of clad steel, the effect of thermal treatment (temperature, holding time) on the interfacial strength of clad steel was preliminarily investigated. From this study, it was confirmed that the interfacial strength of clad steel was deteriorated by thermal treatment and the amount of strength deteriorated, depending on the condition of thermal treatment, could be evaluated by the following equation. ${\sigma}_{ HT}/{\sigma}_{i}/=A_{0}-A\;exp(-Q/RT)log(t/t_{0})$ This equation implies that temperature has a far strong effect on strength deterioration than tiem. The deterioration of interfacial strength of clad steel after thermal treatment may be derived from the thermal stress caused by the difference in thermal expansion coefficient between component materials and microstructural change along the interface.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.26 no.6_spc
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• pp.744-754
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• 2016

A large satellite communication terminal on the truck shall be designed ruggedly against a disturbance for holding a position which satisfies communication performance. Especially. A design considering a wind is essential for getting into a communication with a satellite in a strong-wind condition. This paper suggests a experimental method to analyze performance of a radio wave and the aiming accuracy by wind vibration. And it analyzes the improvement and vibrational effect on a random-excitation of a structure caused by nonlinear strong wind.

• Journal of applied mathematics & informatics
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• v.42 no.2
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• pp.379-390
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• 2024

This study proposes a fuzzy inventory model for managing large-scale production, incorporating cost considerations. The model accounts for two types of expenditure scenarios-parametric and exponential. Uncertainty surrounds holding costs, setup costs, and demand rates. The approach considers a supply chain system with a complex manufacturing process, factoring in transportation costs based on the quantity of goods and distance between the supplier and retailer. The initial crisp model is then transformed into a fuzzy simulation, incorporating specific fuzzy variables affecting inventory costs. The proposed method significantly reduces overall inventory costs for the entire supply chain. Retailer demand is linked to inventory levels, and vendor/distributor storage deteriorates over time. The fuzzy condition assumes hexagonal variables for all associated factors. The study employs the signed distance method for defuzzification to determine the optimal order quantity with hexagonal fuzzy numbers. Mathematical examples are provided to illustrate the practicality of the proposed approach.