• 한국경영과학회지
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• 제32권1호
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• pp.93-104
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• 2007

We consider a supply chain where products are shipped to warehouse from manufacturing system to customers. Products are supplied from either in-house regular manufacturing or the secondary source such as subcontractor. The inventory in warehouse is controlled by base-stock policy, that is, whenever a demand arrives from customer, an order is released to the manufacturing system. Unsatisfied demand is backlogged. The manufacturing system is modeled as M/M/s+1/c queueing system, and the orders exceeding the given limit care blocked and lost. The steady state distribution of the outstanding orders and the throughput of the manufacturing system are functions of the level of engagement In the secondary source. There is a profit obtained from throughput and cost not only due to the engagement of the secondary source in the manufacturing system but also inventory positions. We want to maximize the total production profit minus the total cost of the production system by simultaneously determining the optimal level of engagement of the secondary source and the optimal base-stock level of the inventory. We develop two algorithms : one without guarantee of the optimal solution but with the small number of computations, the other optimal but with more computations.

• 농업과학연구
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• 제23권1호
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• pp.150-158
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• 1996

The potato has been used as a part of key staple foods in Korea. Recently, the demand for the potato tends to increase due to its nutritional Quality, and the Quantity of imports has rapidly been increasing. Contamination of seed potato by pathogens especially could cause a severe reduction of total production. In order to solve the problem, Korea Research Insistute of Bioscience and Biotechnology(KBIBB) developed the new commodity called a "potato microtuber". Before its production and distribution, researches on new commodity should be undertaken in many aspects, especially in terms of economic aspects. The main objectives of this study are to measure the economic value of the potato microtubers and to forecast its spreading effects and to examine the Contingent Valuation Method(CVM) could be accepted in the economic analysis for a new agricultural product, here in potato microtubers. Through the regression results, the consumer behavior analysis had performed for potential users of potato microtubers, and through the demand function derived by the consequence of functional relationship, consumer's surplus was estimated.

• 한국해양공학회지
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• 제8권1호
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• pp.33-40
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• 1994

Welding of structure produces welding residual stresses which influence buckling strength, brittle fracture strength and cold crack on the weld parts. Therefore, it is very important to accurately analyze the residual stress before welding in order to guarantee the safety of weldment. If the weld length is long enough compared to the thickness and the breadth of plate, thermal and mechanical behaviors in the middle portion of the plate are assumed to be uniform along the thickness direction(z-axis). Thus, the following conditions(so-called plane deformation) can be assumed for the plate except near its end;1) distributions of stress and strain are independent on the z-axis;2) plane normal to z-axis before deformation remains plane during and after deformation. In this paper, plane-deformation thermal elasto-plastic problem is formulated by being based on the finite element method. Moreover special regards and paid to the fact that material properties in elastic and plastic region are temperature-dependence. And the method to solve the plane-deformation thermal elasto-plastic problem is shown by using the incremental technique. From the results of analysis, the characterisics of distribution of welding residual stress and plastic strain with the production mechanism are clarified.

• 산업경영시스템학회지
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• 제10권16호
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• pp.143-147
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• 1987

Safety stocks constitute one of the major means of dealing with the uncertainties associated with variation in demand and lead time. Adeguate safety facilitate production activities and help to assure customers if good service on the other hand, carrying safety storks ties up working capital on goods that sit idle. The major problem of safety stocks management thus of consists of trying to achieve an optimal balance between the other carrying cost and the costs of stock shortage. Therefore, this study aims to find safety stock level of the fixed reorder quantity system and the fixed reorder cycle system of minimizing total cost when both demand and lead time are variable. (The distribution of demand and lead time is a mere assumption that follows the normal distribution) The results can be summarized as follows. i) Safety factor on the safety stock is determined by carrying cost and the costs of stock shortage: An optimal safety stick=the costs of stork shortage($C_s$) (the carrying cost($C_h$)+the costs of stock storage($C_s$). ii) The safety stock level of the fixed reorder quantity system is ($a{\;}_p\sqrt{L}{\sigma}$) under uncertainties. iii) The safety stock level of the fixed reorder cycle system is ($a{\;}_p\sqrt{R+L{\sigma}}$) under uncertain demand and constant lead time. ($a{\;}_p\sqrt{L{\sigma}_d{\;^2+{\mu}^2L{\sigma}^2}$) under demand and lead time uncertainties.

• Fisheries and Aquatic Sciences
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• 제22권7호
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• pp.14.1-14.8
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• 2019

Olive flounder (Paralichthys olivaceus) is the major species developed for aquaculture in South Korea. Over the long history of olive flounder aquaculture, complex and diverse diseases have been a major problem, negatively impacting industrial production. Vibriosis is a prolific disease which continuously damages olive flounder aquaculture. A bacterial disease survey was performed from January to June 2017 on 20 olive flounder farms on Jeju Island. A total of 1710 fish were sampled, and bacteria from the external and internal organs of 560 fish were collected. Bacterial strains were identified using 16 s rRNA sequencing. Twenty-seven species and 184 strains of Vibrio were isolated during this survey, and phylogenetic analysis was performed. Bacterial isolates were investigated for the distribution of pathogenic and non-pathogenic species, as well as bacterial presence in tested organs was characterized. V. gigantis and V. scophthalmi were the dominant non-pathogenic and pathogenic strains isolated during this survey, respectively. This study provides data on specific Vibrio spp. isolated from cultured olive flounder in an effort to provide direction for future research and inform aquaculture management practices.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2007년도 춘계학술대회
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• pp.621-625
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• 2007

Oscillating wave amplitude in a bottom-mounted owe chamber designed for wave energy converter is investigated by applying characteristic wave conditions in Korean coastal water. The effects of shape parameters of OWC chamber in a view of wave energy absorbing capability are analyzed. Both experimental and numerical approaches are adopted and their results are compared to optimize the shape parameters which can result in a maximum power production under given wave distribution. The experiment was carried out in a wave flume under 2-D assumption of OWC chamber. In numerical scheme, the potential problem inside the chamber is solved by use of the Green integral equation associated with the Rankine Green function, while outer problem with the Kelvin Green function taking account of fluctuating air pressure in the chamber. Air duct diameter, chamber width, and submerged depths of front skirt and back wall of chamber changes the magnitude and peak frequency of wave absorption significantly.

• Industrial Engineering and Management Systems
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• 제4권2호
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• pp.145-157
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• 2005

There are a lot of raw materials, work-in-processes and finished goods in manufacturing industry. Here, the less stock of materials and work-in-processes manufacturing industry has, the worse the rate of the production is. Inversely, the more manufacturing industry has, the more expensive the cost to support them is. Thus, it is important for us to balance them efficiently. In general, inventory problems are to decide appropriate times to produce goods and to determine appropriate quantities of goods. Therefore, inventory problems require as more useful information as possible. For example, there are demand, lead time, ordering point and so on. In this paper, we deal with an optimal ordering policy on both way substitutable two-commodity inventory control system. That is, there is a problem of how to allocate the produced two kinds of goods in a factory to m areas so as to minimize the total expected inventory cost. The demand of each area is probabilistic, and we adopt the exponential distribution as a probability density function of demand. Moreover, we provide numerical examples of the problem.

• 한국정밀공학회지
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• 제16권11호
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• pp.22-35
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• 1999

The block assembly process takes more than half of the total shipbuilding processes. Therefore, it is very important to have a practically useful block assembly process planning system which can build plans of maximum efficiency with minimum man-hours required. However, the process plans are often not readily executable in the assembly shops due to severe imbalance of workloads. This problem arises because the process planning is done on block by block basis in current practice without paying any attention to the load distribution among the assembly shops. this paper presents the development of an automated hull block assembly process planning system which results in the most effective use of production resources and also produces plans that enable efficient time management. If the load balance of assembly shops is to be considered at the time of process planning, the task becomes complicated because of the increased computational complexity. To solve this problem, a new approach is adopted in this research in which the load balancing function and process planning function are iterated alternately providing to each other contexts for subsequent improvement. The result of case study with the data supplied from the shipyard shows that the system developed in this research is very effective and useful.

• 대한치과기공학회지
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• 제34권2호
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• pp.179-199
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• 2012

Purpose: This study was conducted to prepare the fundamental data on oral hygiene of the elderly and to assess the behavior of oral hygiene, subjective oral health, oral health problem among the elderly, and to contribute to successful enhancement of life in their declining years. Methods: The author surveyed the behavior of oral hygiene, subjective oral health, oral health problem to 192 elderly at a health center of Busan using structured self- administered questionnaire from Nov. 2nd 2009 to Feb. 10th 2010. Collected data were analysed by SPSS WIN 18.0 statistical program for frequency, percentage production, ${\chi}^2$ (Chi-square) verification, t-test, One-way ANOVA, Logistic Regression. Results: The distribution of total subjects by oral health behaviors were 56.8% for "have ever trained how to tooth brushing", 76.6% for "correctly performed tooth brushing by himself ", 71.8% for "tooth brushing a day is two times and less", 87.5% for "it doesn't tooth brushing in meals and after" and 53.6% for "it doesn't use the facility for oral health", respectively. The distribution of total subjects by the state of perceived oral health were 51.0% for "feel the oral discomfort", 51.6% for "feel the comfortable chewing on starchy food", respectively. The mean point of perceived oral health by general characteristics of total subjects were statistically significant difference in sex, type of medical insurance, smoke, exercise, and chronic disease. The mean point of perceived oral health by oral health behaviors of total subjects were statistically significant difference in educational experience on tooth brushing, recognition for tooth brushing by himself, tooth brushing a day, and tongue cleaning. The risk factors of perceived oral health were type of medical insurance and chronic disease in general characteristics, tooth brushing in meals and after and tooth brushing a day, and tongue cleaning in oral health behaviors. Conclusion: The author recommend to the prevention of chronic disease, carry out the tooth brushing in meals and after, three times and over tooth brushing a day and tongue cleaning for oral health. and the author consider that it need to prepare the active countermeasure to oral health such as reeducation for oral health and supply to the tongue cleaner.

• 한국산업정보학회논문지
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• 제14권1호
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• pp.43-55
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• 2009

본 연구는 뉴미디어 플랫폼이 콘텐츠산업의 창작과 유통에 미치는 영향을 시장상황 분석 및 전문가 진단을 통해 실제적으로 규명 해내는데 목표를 두었다. 콘텐츠산업의 현실진단을 위해서 시장분석과 업계 종사자 및 관련 전문가를 대상으로 한 심층면접 방법을 활용하였다. 진단결과, 다양한 뉴미디어 플랫폼의 상용화가 국내 콘텐츠산업의 창작 활성화 및 유통구조 합리화를 충분히 견인하지 못하고 있는 것으로 나타났다. 국내의 콘텐츠창작 분야는 유통채널의 증가에도 불구하고 새로운 포맷의 다양한 콘텐츠 생산이 활성화되지 못하고 있다. 또한 기존의 인기콘텐츠를 생산하는 소수의 거대 창작업체에 플랫폼 다양화의 혜택이 집중되고 있고, 창작업체의 영세성이 극복되지 못한 가운데 양극화가 심화되고 있는 것으로 분석된다. 콘텐츠유통 분야의 경우 유통되는 콘텐츠는 기존의 인기콘텐츠가 대부분이며, 불공정한 콘텐츠거래관행이 지속되고 있는 것으로 나타났다 이러한 현실적 문제들을 개선하기 위한 혁신적 정책이 요구되는데, 문화콘텐츠산업 생태계가 선순환구소를 형성하도록 조정 역할을 수행해야 한다는 것이다.