• Magazine of the Korean Society of Agricultural Engineers
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• 제37권5호
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• pp.53-61
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• 1995

Analyses of subsurface drainage effects of farmland with respect to pipe and envelop material are made by the laboratory experiments using soil box to give basic information for the subsurface drainage system planning and design. Three different diameter PVC perforated pipes and a mesh pipe are used with envelop materials such as sand, rice bran, and crushed stone. Steady state subsurface drainage flow rate increased as envelop material changed from sand to rice bran and crushed stone. This indicates that as the hydraulic conductivity of the envelop material increases, the drainage flow rate increases. On the other hand, for a given envelop material, the mesh pipe which has the largest openning area shows the largest flow rate while small diameter PVC pipes show small flow rates. This tells that as the openning area and pipe diameter increase, the flow rate increases, too. Therefore, selection of pipe and envelop material should be made in accordance with the design drainage flow rate. Unsteady state subsurface drainage flow rate with respect to time differs for different envelop material. In case the sand was used as an envelop material, the small diameter PVC pipes show larger flow rates than the large diameter PVC pipe and mesh pipe. When the rice bran was used, the mesh pipe shows the largest flow rate, while small diameter pipes show smaller flow rates. In case the crushed stone was used as an envelop material, the large diameter PVC pipe and mesh pipe show larger flow rates, while small diameter pipes show a little bit smaller flow rates. However, the variation of flow rates among different pipes is the smallest when the crushed stone is used. The flow rate curve with respect to the pipe changes little for the crushed stone envelop which has a large hydraulic conductivity, while that changes much for the sand and rice bran envelops. However, it is difficult to draw a consistent relationship between the drainage flow rate and pipe for all the envelop materials. Since the subsurface drainage experiments are made only under the restricted laboratory condition in this study, further study including field experiment is required.

• IE interfaces
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• 제10권3호
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• pp.179-187
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• 1997

The efficiency of material flow systems in terms of optimal network flow and minimum cost flow has always been an important design and operational goal in material handling and distribution system. In this research, an attempt was made to develop a new algorithm and the model to solve a stochastic material flow network with bidirectional and uncertain flows. A stochastic material flow network with bidirectional flows can be considered from a finite set with unknown demand probabilities of each node. This problem can be formulated as a special case of a two-stage linear programming problem which can be converted into an equivalent linear program. To find the optimal solution of proposed stochastic material flow network, some terminologies and algorithms together with theories are developed based on the partitioning and subgradient techniques. A computer program applying the proposed method was developed and was applied to various problems.

• Special Issue of the Society of Naval Architects of Korea
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• 대한조선학회 2005년도 특별논문집
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• pp.151-158
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• 2005

It is important to control material flow in shipbuilding as it decides the productivity of production, cost and period of production. The weight of material in a big shipyard is even more one million tons. The results contained in this paper can provide the valuable information on the effect of reduction of cost and competitive power. The intention of this paper is to let ship builders pay attention to material flow. This paper refers to other manufacture's methods to improve their material flow and also give one example to show how to pursue to improve material flow in a shop. We have still lots of room to improve material flow.

• Transactions of Materials Processing
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• 제11권5호
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• pp.430-438
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• 2002

This paper suggests the new technology to control metal flow in orther to change of the cold forging from conventional deep drawing forming. This technology can be summarized the complex forming, which consists of bulk forming and sheet forming, and multi-action forging, which be performed double action press. The proposed technology is applied to hub clutch model which is part of auto-transmission for automobile. The purpose of this study is to investigate the material flow behavior of hub clutch through control the relative velocity ratio and the stroke of mandrel and punch using the flow forming technique. First of all, the finite element simulations are applied to analyse optimal process conditions to prevent flow defect(necking defect etc.) from non-uniform metal flow, then the results are compared with the plasticine model material experiments. The punch load for real material is predict from similarity law. Finally, the model material experiment results are in good agreement with the FE simulation ones.

• The Journal of Asian Finance, Economics and Business
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• 제9권5호
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• pp.475-486
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• 2022

The purpose of this paper is to examine the use of material flow cost accounting (MFCA) in Vietnam's coal-fired thermal power plants. This study is based on the contingency and system theories to explain the application of management tools and analyze steps of input, output, and process in manufacturing. Costs in producing process-based MFCA include material cost, energy cost, system cost, and waste management cost. The exploratory case study methodology is used to describe and answer two questions, namely "How coal flow cost is recognized?" and "Why waste in material consumption can be harmful to the environment?". By analyzing the Quang Ninh and Pha Lai coal-fired thermal power plants that are the typical plants, this paper identifies the flow of primary material in these plants as a basis for determining losses for the business. The material flow of coal-fired thermal power plants provides the basis for the use of the MFCA. The manufacturing of electrical items in these plants is divided into four stages, each with its own set of losses. As a result, some phases in the application of MFCA are suggested, as well as some other elements required for MFCA application in coal-fired thermal power plants.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 한국소성가공학회 2001년도 제4회 압출 및 인발가공 심포지엄
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• pp.1-12
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• 2001

In cold forging of piston-pin for automobile parts, the flow defect appears by the dead metal zone. This appearance evidently happens in products with a thin piercing thickness for the dimension accuracy and the decrease of material loss. The best method that can prevent flow defect is removing dead metal zone. The purpose of this study is to investigate the material flow behavior of forward-backward extruded piston-pin through the relative velocity ratio and the stroke control of upper moving punch & container using the flow control forming technique. The finite element simulations are applied to analyse the flow defect, then the results are compared with the plasticine model material experiments. Finally, the model experiment results are in good agreement with the FE simulation ones.

• Transactions of the Korean Society of Mechanical Engineers A
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• 제26권7호
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• pp.1366-1375
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• 2002

In cold forging of piston-pin for automobile parts, the flow defect appears by the dead metal zone. This appearance evidently happens in products with a thin piercing thickness for the dimension accuracy and the decrease of material loss. The best method that can prevent flow defect is removing dead metal zone. The purpose of this study is to investigate the material flow behavior of forward-backward extruded piston-pin through the relative velocity ratio and the stroke control of upper moving punch & container using the flow control forming technique. The finite element simulations are applied to analyse the flow defect, then the results are compared with the plasticine model material experiments. The model experiment results are in good agreement with the FE simulation ones.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 한국소성가공학회 2004년도 추계학술대회논문집
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• pp.152-155
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• 2004

In the semi-solid die casting process, the important thing is the flow behaviors of semi-solid material. The flow patterns of semi-solid material can make the defects during die filling. To control of the flow patterns, is very important and difficult. In this paper, the flow behaviors of the semi-solid A356 alloy material during die filling at various die gate shapes has been observed with the grain size controlled material. The effects of the gate shape on the die filling characteristics were investigated. The filling tests in each plunger strokes were experimented, also simulated on the semi-solid material die casting process by MAGMAsofi. According to the filling tests and computer simulation, the effect of the gate shape on liquid segregation had been investigated.

• Economic and Environmental Geology
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• 제39권5호
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• pp.615-626
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• 2006

The natural resources and material life-cycle include all human activities related to resources and material extraction, transportation, processing, use, recovery and disposal. Sustainable material management (SMM) is an integrated set of policy approaches targeted on economic agents throughout the material life-cycles and designed to result in economically efficient and environmentally effective material use. The material flows of industrial mineral, ores and fossil fuels have also long been a focal area for environmental policies because of the high environmental pressures associated with extraction, processing, consumption, and final disposal of these materials. OECD work on material flow is to improve the quantitative and analytical knowledge bases about natural resource and material flows within and among countries, so as to better understand the importance of material resources in member countries' economies. In several EU Member States, material flow accounts are part of official statistics. Material flow analysis (MFA) is a valuation method which assesses the efficiency of use of materials using information from material flow accounting. Material flow analysis helps to identify waste of natural resources and other materials in the economy which would otherwise go unnoticed in conventional economic monitoring systems. Resource use and resource efficiency has emerged as a major issue for long-term sustainability and environmental policy.

• Transactions of Materials Processing
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• 제4권3호
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• pp.245-256
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• 1995

SMC(Sheet Molding Compound), a thermoset composite material which consists of unsaturated polyester resin, fiberglass strands, fillers, and various chemical additives for curing agent, has been widely used in fabrication of structural components. The mechanical properties of molded SMS parts are strongly dependent on material flow results during compression molding process, while such flow in molds is affected by material characteristics. For numerical simulation of SMC molding process, estimation of material property of SMC must be accomplished. In this study, flow resistance of SMC was estimated through a simple compression test using a lubricant with grease oil under the constant strain rate condition at various temperatures and the result was compared with other material data available in the literature. The accuracy of the experimentally determined flow resistance was tested by finite element analyses of compression molding of SMC. Simulation results were compared with experimental results under the plane strain condition.