• 대한산업공학회지
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• 제28권1호
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• pp.1-13
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• 2002

We study a multi-component production/inventory system in which individual components are made to meet various demand types. We assume that the demands arrive according to a Poisson process, but there is a fixed probability that a demand requests a particular kit of different components. Each component is produced by a flow line with several stations. The production of each component is operated by the CONWIP control mechanism. To analyse this system, we propose an approximation method based on aggregation method. In application of the aggregation method, a product-form approximation technique as well as a matrix-geometric method is used. Comparisons with simulation show that the approximation method provides fairly good results.

• 한국경영과학회:학술대회논문집
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• 대한산업공학회/한국경영과학회 2000년도 춘계공동학술대회 논문집
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• pp.135-138
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• 2000

This paper is intended to propose what manufacturing configuration (manufacturing planning and shop floor control) is suitable for the tire industry. Basically tire-manufacturing process is mixed-products, parallel-disconnected-flow-shop. Both throughput time and cycle tine are very short, the variety of tires is very high, the setup time is long, shop floor data reporting requirements is high, and there are many equipments and people working. And with no exception, tire industry also now confronts increasing requirements of delivery conformance with the above peculiar characteristics of tire manufacturing and changing market environments, this paper suggests, weekly master scheduling with no MRP is desirable and traditional kanban is right selection for shop floor control/scheduling. This paper describes why this configuration should be, using the manufacturing engineering principles and some new insights like four primitives of parallel flow shop. Generally known that shop with high parallel-product-mix and long setup time isn't good candidate for kanban. The four primitives of parallel flow shop explain why kanban is also useful scheduling technique in that environment.

• 한국시뮬레이션학회논문지
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• 제8권1호
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• pp.63-76
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• 1999

Recently in manufacturing environment, manufacturing order is characterized by unstable market demand, shorter product life cycle, a variety of product and shorter production lead time. In order to adapt this manufacturing order, flexible manufacturing systems(FMS) in manufacturing technology advances into the direction that machines become further versatile functionally and that tools are controlled by fast tool delivery device. Unlike conventional FMS to mainly focus on part flow, it is important to control tool flow in single-stage multimachine systems(SSMS), consisting of versatile machines and fast tool delivery device. This research is motivated by the thought that exact estimation of tool competition at part release in SSMS enhances the system performance. In this paper, in SSMS under dynamic tool allocation strategy to share tools among machines, we propose real-time part release and tool allocation algorithms which can apply real factory and which can improve system performance.

• 한국시뮬레이션학회:학술대회논문집
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• 한국시뮬레이션학회 1999년도 춘계학술대회 논문집
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• pp.60-64
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• 1999

Recently in manufacturing environment, manufacturing order is characterized by unstable market demand, shorter product life cycle, a variety of product and shorter production lead time. In order to adapt this manufacturing order, flexible manufacturing system(FMS) in manufacturing technology advances into the direction that machines become further versatile functionally and that tools are controlled by fast tool delivery device. Unlike conventional FMS to mainly focus on part flow, it is important to control tool flow in single-stage multimachine systems(SSMS), consisting of versatile machines and fast tool delivery device. In this paper, in SSMS under dynamic tool allocation strategy to share tools among machines, we propose real-time part release and tool allocation algorithms which can apply real factory and which can improve system performance.

• 한국산학기술학회논문지
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• 제11권1호
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• pp.278-286
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• 2010

본 연구는 새로운 유통환경인 인터넷환경에서 디지털 콘텐츠의 충동구매에서의 마케팅 자극, 플로우, 자기행동통제 및 감각추구성향간의 영향을 살펴보고자 하였다. 이를 위해 충동구매 동기요인을 기존의 연구들에서 제시된 마케팅자극을 이용하였다. 구매자의 마케팅자극으로 디지털 콘텐츠 구매자들이 받게 되는 제품자극, 가격자극, 촉진자극으로 구분하여 구매자의 충동구매행동에 미치는 영향을 검증하였다. 이때 구매행위 전에 자신이 받은 자극에 대해 플로우를 경험하는 과정이 나타날 것이다. 플로우(FLOW)는 구매행위자가 받은 자극을 보다 강화시키는 충동구매행위의 중요한 요소가 될 것이다. 이처럼 인터넷 환경에서는 기존의 충동구매 과정과는 달리 충동구매자극 이후에 더 많은 정보를 획득할 수 있고 쉽고 빠르게 구매할 수 있기 때문에 마케팅자극이외에 구매자의 심리적인 측면이나 성향등이 충동구매행동에 있어 보다 중요한 역할을 하게 될 것이다. 행위에 대한 자신의 능력 및 통제 가능성인 자기행동 통제에 따라서 충동구매행동이 다르게 나타나게 될 것이다. 또한 구매자들이 가지고 있는 구매자들의 성향 중에 감각 추구성향은 충동구매를 하는데 조절역할을 하는지에 대한 검증을 하였다. 이를 통해 디지털 콘텐츠 충동구매와 관련된 학문적인 시사점과 더불어 디지털 콘텐츠 마케터들의 효과적인 마케팅 전략수립에 도움을 주고자 한다.

• Asian-Australasian Journal of Animal Sciences
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• 제9권6호
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• pp.655-665
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• 1996

The effects of feeding rice bran and beet pulp mixtures on the site and extent of digestion and microbial synthesis in fattening steers were studied. Three Holstein steers fitted with ruminal, duodenal and ileal cannulas were fed four diets in a $4{\times}3$ Youden square design. The four diets consisted of 15% Italian ryegrass hay and 85% concentrate as a control diet which included 72% rolled barley, 20% rice bran plus 40% beet pulp, 30% rice bran plus 30% beet pulp or 40% rice bran plus 20% beet pulp. All diets provided 1.8 times digestible energy required for maintenance. The digestibility of fat in the small intestine (% of flow) showed an increase with rice bran content among the by-product diets. Digestibility of structural carbohydrate both in the rumen and the whole digestive tract decreased linearly with rice bran content. The digestibility of nonstructural carbohydrate was not affected by rice bran content, but that of nonstructural, nonstarch polysaccharides was higher in the rumen and lower in the large intestine for the by-product diets than for the control diet. A rice bran content of more than 30% in the by-product diets severely inhibits ruminal microbial synthesis and digestible energy intake in fattening steers.

• 제어로봇시스템학회논문지
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• 제12권9호
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• pp.945-953
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• 2006

Though a fully thermally coupled distillation column consumes less energy than an original column, it is not widely implemented in practice due to its operational difficulty. A new fully thermally coupled distillation column is proposed for the operability improvement, and its performance is investigated. The main improvement is the separation of a main column to give an upper and lower columns and the installation of an intermediate heat exchanger between them to regulate the fluctuation of product compositions. A proper manipulation of column pressure in the separated main columns made easy vapor flow without a compressor. The operability improvement is examined in a hexane process from the dynamic simulation using a commercial design software HYSYS. The simulation results indicate that the coupling among inputs and outputs is loosened to make easy manipulation of product compositions in the proposed distillation system.

• 한국공작기계학회논문집
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• 제10권2호
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• pp.103-114
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• 2001

During a compression molding process of Unidirectional Fiber Reinforced Plastic Composites, control of filling patterns in mold and distribution of fiber is needed to predict the effects of molding parameters on the flow characteristics. To obtain an excellent product and decide optimum molding conditions, it is important to know the relationship between molding conditions and viscosity. In this study, the anisotropic viscosity of the Unidirectional Fiber Reinforced Plastic Composites is measured by using the parallel plastometer. The model for flow state has been simulated by using the viscosity. The composites is treated as an incompressible New-tonian fluid. The effects of longitudinal/transverse viscosity ration A and slip parameter $\alpha$ on buldging phenomenon and mold filling patterns, are also discussed.

• 수산해양기술연구
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• 제51권2호
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• pp.155-162
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• 2015

Abalone (Haliotis discus hannai) is a shellfish that feeds on kelp and, as a product, it can often achieve a high market value. However, the dissolved oxygen (DO) levels in coastal waters in Korea have been negatively impacted by pollution from many anthropogenic sources. Herein, a computational fluid dynamics (CFD) software package was used to analyze the distribution of the DO concentration within an abalone containment structure. A finite volume approach was used to solve the Reynolds-averaged Navier-Stokes equations combined with a $k-{\varepsilon}$ turbulence model to describe the flow. The distribution of DO was determined within the control volume domain, and the transport equations of the pollutants were interpreted using a CFD model. The CFD analysis revealed that more than 60% and 30% of the relative oxygen concentration in one and two containers, respectively, was maintained when the flow acts along the six sheets of polyethylene plates. Therefore, it is clear that the abalone plate shelters should be placed parallel to the flow.

• International Journal of Aerospace System Engineering
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• 제5권2호
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• pp.16-22
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• 2018

An analysis has been made on the performance variation due to pressure drop change at propellant supply pipes of liquid rocket engine. The objective is to compare the effectiveness of control variables to tune the liquid rocket engine performance. The mode analysis program has been used to estimate the engine performance for different modes which is realized by controlling the flow rate of propellant. The oxidizer of combustion chamber, the fuel of combustion chamber, the oxidizer of gas generator and the fuel of gas generator are the independent variables to control engine thrust, engine mixture ratio and temperature of gas generator product gas. The analysis program is validated by comparing with the powerpack test results. The error range of compared variables is order of 4%. After comparison of tuning effectiveness it is turned out that the pressure drop at oxidizer pipe of gas generator and pressure drop at combustion chamber fuel pipe and the pressure drop at the fuel pipe of gas generator can effectively tune the thrust of engine, mixture ratio of engine and temperature of product gas from gas generator respectively.