• Journal of the Korea Society for Simulation
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• v.11 no.3
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• pp.67-77
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• 2002

In this paper, a production process system simulation of the automobile relay switch manufacturing factory is studied. The status of the present production system is inspected first, and the modified model is simulated next. To inspect the effect of the process parameter change, a simulation program is developed using PROMODEL simulation software plus the EXCEL VBA and Active X Automation function. Using the developed simulation program, user can find the best production condition and alternatives on the production capacity, number of workers, and inspection status considering the defective ratio of the product. The feasibility of the new alternatives is compared with the present system using statistical method.

• Journal of Korean Institute of Industrial Engineers
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• v.25 no.2
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• pp.240-253
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• 1999

In this paper we propose new approximate methods for the performance analysis of closed-loop production systems with unreliable machines and random processing times. Each approximate method decomposes the production system consisting of K machines into a set of K subsystems, each subsystem consisting of two machines separated by a finite buffer. Then, each subsystem is analyzed by three different analyzing methods in isolation. The population constraint of the closed-loop production system is taken into account by prescribing that the sum of average buffer levels in the subsystems is equal to the number of customers in the closed-loop production system. We establish a set of equations that characterize unknown parameters of the servers in the subsystems. An iterative procedure is then used to determine the unknown parameters. Experimental results show that these methods provide a good estimation of the throughput.

• International conference on construction engineering and project management
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• 2009.05a
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• pp.51-59
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• 2009

Lean construction researchers and practitioners have established a new paradigm for managing construction projects. This paradigm stems from insights gained by viewing project delivery as one kind of production and, inspired by the success of the Toyota Production System, leveraging Toyota's 'lean thinking' in the context of such one-of production. Premises of lean construction are that (1) production systems are riddled with variation, (2) variation can be good or bad, but most of it is bad, (3) most of this variation-good or bad-is self-inflicted; consequently 'lean' passionately promotes good- and relentlessly eradicates bad variation. This paper surveys a few of many lean construction means to manage variation. Lean thinking encompasses a lot more than thinking about variation, but that is the lens used here through which construction project management is viewed. Pairing these premises with lean variation-management tools may help readers broaden the insights they can gain from reading the lean construction literature.

• New & Renewable Energy
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• v.3 no.4
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• pp.90-97
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• 2007

Gasification has been regarded as a very important technology to decrease environmental pollution and to obtain higher efficiency. The coal gasification process converts carbon containing coal into a syngas, composed primarily of CO and $H_2$. And the coal syngas can be used as a source for power generation or chemical material production. This paper illustrates the opeartion characteristics and results of pilot-scale coal syngas production facilities. The entrained-bed pilot scale coal gasifier was operated normally in the temperature range of $1,300{\sim}1,400^{\circ}C,\;2{\sim}3kg/cm^2$ pressure. And Indonesian KPC coal produced syngas that has a composition of $46{\sim}54%\;CO,\;20{\sim}26%\;H_2,\;and\;5{\sim}8%\;CO_2$.

• Korean System Dynamics Review
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• v.10 no.3
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• pp.105-124
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• 2009

The situation of the global food markets has been being rapidly restructured and entering on a new phase by new dynamic and driving forces. The factors such as economic growth and income increase, high energy price, globalization, urbanization, and global climate change are transforming patterns of food consumption, production, and markets. The prices and markets of world food and energy are getting increasingly linked each other. Food and fuel are the global dilemma issues associated with the risk of diverting farmland or of consuming cereals for biofuel production in detriment of the cereals supply to the global food markets. An estimated 100 million tons of grain per year are being redirected from food to fuel. Therefore, the objectives of this study are as follows: Firstly, the study examines situations of the world food and energy resources, analyzes the trends of prices of the crude oil and biofuel, and formulates the food-energy links mechanism. Secondly, the study builds a simulation model, based on system dynamics approach, for not only analyzing the global cereals market and energy market but also forecasting the global production, consumption, and stock of those markets by 2030 in the future. The model of this study consists of four sectors, i.e., world population dynamics sector, global food market dynamics sector, global energy market dynamics sector, scenario sector of world economic growth and oil price.

• KSBB Journal
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• v.13 no.5
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• pp.547-553
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• 1998

For the efficient production of a new exo-polysaccharide from Ganoderma lucidum ASI 7004, the optimum conditions and methods in submerged cultivation were investigated with an airlift fermenter system. The optimum aeration rate was 2.5 Wm at the initial pH 5.0 and 28$^{\circ}C$. The increase of dissolved oxygen concentration by pure oxygen supply during cultivation did not improved the exo-polysaccaride production and the mycelial growth. The maximum exo-polysaccharide production and the mycelial growth under the optimum culture condition were obtained in media of glucose 60g/L, yeast extract 6g/L, (NH4)2HPO4 1g/L and KH2PO4 0.5g/L. Under these optimum medium and culture conditions, about 7.15g/L of exo-polysaccharide and 13.9g/L of mycelial growth were producted, respectively.

• IE interfaces
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• v.20 no.3
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• pp.245-256
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• 2007

Toyota Production System (TPS) has been known a new production paradigm applicable to every type of manufacturing industry, not restricted to automobile assembly system. The basic framework of TPS has been studied and presented actively; many enterprises from all over the world including some of large domestic companies, have adopted and applied. This study analyzed the cases for TPS introduction and application process of LG Electronics and SAMSUNG Electronics, Semiconductor Division. On a different areas of business items, different strategic approaches are developed and implemented on a two comparable domestic companies. Key success factors for two companies are analysed, and some issues are also discussed.

• Journal of the Korea Safety Management & Science
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• v.4 no.4
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• pp.73-85
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• 2002

The supply chain not only includes the manufacturer and suppliers, but also transporters, warehouses, retailers, and customers themselves. Within each organization, such as manufacturer, the supply chain includes all functions involved in filling a customer request. these functions include, but are not limited to, new product development, marketing, operation, distribution, finance, and customer service. Lean Supply chain coordination improves if all supplier of chain take actions that together increase total supply chain profits. To design of Modularity by the grouping supplier, the proposed method is to develop the most appropriate production system models in the Supply Chain Management which is necessity of the times and its importance. The objects of this study is development of model and cost analysis to the modular production system in Lean SCM. Introduction of modular production system in Lean SCM is effective in reducing the cost in processing, manufacturing, inventory holding, ordering, etc.

• New & Renewable Energy
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• v.20 no.1
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• pp.110-115
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• 2024

Global sustainable energy needs and carbon neutrality goals make hydrogen a key future energy source. South Korea and Japan lead with proactive hydrogen policies, including South Korea's Hydrogen Law and Japan's strategy updates aiming for a hydrogen-centric society by 2050. A notable advance is the solar thermal chemical water-splitting cycle for green hydrogen production, spotlighted by Korea Institute of Energy Research (KIER) and Niigata University's joint initiative. This method uses solar energy to split water into hydrogen and oxygen, offering a carbon-neutral hydrogen production route. The study focuses on international collaboration in solar energy for thermochemical water-splitting and E-fuel production, highlighting breakthroughs in catalyst and reactor design to enhance solar thermal technology's commercial viability for sustainable fuel production. Collaborations, like ARENA in Australia, target global carbon emission reduction and energy system sustainability, contributing to a cleaner, sustainable energy future.

• 연구논문집
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• s.25
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• pp.77-90
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• 1995

For improving performance of heat pump system, researcher has adapted 2-stage economizer cycle and developed a high-efficiency screw compressor, new working medium(non-azeotropic mixed refrigerant) and counterflow heat exchangers operating with a small temperature difference. Target of this study is development of high performance heat pump system with the 2-stage economizer system using the non-azeotropic mixed refrigerant. For the purpose of excuting target, we constucted computer simulation programs, compared and examed various types of cycle and non-azeotropic mixture. Based on the results from computer simulation we selected optimum mixtures and reflected design and production process of performance test equipment with the 1-stage econmizer system. In order to accomplish the final target, design and production of the 2-stage economizer system, we performed pilot test using the 1-stage economizer performance test system and finally design and production of the 2-stage economizer system.