• Journal of the Korean Society for Railway
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• v.9 no.5 s.36
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• pp.524-531
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• 2006

Environmental problem is one of important global issues. Transportations are main pollutant emission sources. Although railroad is stilt an environmental-friendly transportation, its environmental impact has been increased continuously. Especially, because a large amount of environmental impact is released from vehicles and facilities, it is necessary to assess and to reduce their environmental impact. Life cycle assessment (LCA) is a representative method which can evaluate environment impact through the whole life cycle of a product or a process. In this study, the environmental impact of seat in the electric motor unit (EMU) was analyzed quantitatively with its material using lift cycle assessment (LCA). As a result, the characteristics of environmental impact were investigated differently with the material of seat. Among ten impact categories, the seat with aluminum and FRP showed the highest ozone depletion (OD). On the other hand, in the seat with stainless steel and plastic, fresh water aquatic ecotoxicity (FAET) and marine water aquatic ecotoxicity (MAET) were high relatively. Therefore, the parts of EMU must be selected considering the characteristics of environmental impact in future.

• Journal of the Korean Recycled Construction Resources Institute
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• v.3 no.2
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• pp.115-121
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• 2015

The objective of this study is to present the design approach of low $CO_2$ concrete structures for reduction of $CO_2$ emissions. The design approach was implemented considering the system boundary for each processing presented in the ISO 13315-2. As for life-cycle inventory(LCI) for $CO_2$ assessment of concrete structures, data provided from domestic LCI DB was used. Based on the process presented in this study, case studies on the life-cycle $CO_2$ assessment of shear wall concrete structure was conducted. As substitution level of GGBS is 25%, the amount of $CO_2$ emissions and $CO_2$ uptake by concrete carbonation was decreased in the material, demolition and crushing, and transport phase. The amount of $CO_2$ emissions of column and total member was decreased by 26% and 22% respectively, compared to that of OPC.

• Journal of Energy Engineering
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• v.12 no.4
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• pp.328-338
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• 2003

A study is perfomed on the difference between the volume of gas purchased from Korea Gas Corporation (KGC) and that of measured gas deliveries including total sales, pipeline inventory, and other usage by gas companies at Seoul and Kyunggi area. Actual data md information from 1996 to 2001 on gas purchase from KGC, sales, loss and own company use and pipeline status of each gas company are used to identify net inventory change in pipeline, unaccounted inventory estimates based on billing cycle and their net changes. A framework to be used for the analysis of such differences and an empirical test result are being provided. As a conclusion, the hypothesis that each gas company purchased more than the volume of gas accounted-for by all the possible factors is shown to be rejected.

• Journal of applied mathematics & informatics
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• v.26 no.3_4
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• pp.739-750
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• 2008

A phenomenon which is seen in some of the manufacturing systems and production planning is chaos and the butterfly effect. The butterfly effect points out that in case of the presence of nonlinear relations in system and incorrect estimation of initial values of variables, the error in the estimates of system state will be intensified, and after a while there will be a large distance between available state of system and reality. Using mathematical means and computer simulation, we have tried to demonstrate that in a production system the numerical combination of Cycle Time (CT), Adjustment Time between existing and desired Work In Progress (WIP), and Adjustment Time between current and desired inventory can lead to chaos and butterfly effect in the behavior of the inventory state variable. Our paper concludes with a discussion of a hypothesis that emerged from this research.

• Journal of Distribution Research
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• v.1 no.2
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• pp.141-172
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• 1996

This study is to investigate global logistics strategies of Korean electronics companies. in terms of service parts. According to the survey, Korean electronics companies were pursuing multi-level global logistics network such as global, continental, national, regional and service center echelon for improving the efficiency of service parts global logistics. Especially there was a tendency of developing new continental distribution centers. And the companies were exploiting efficiency through inventory control by multi-level echelon, demand forecasting by the product life cycle and supply and service lead time management. But there were some insufficient factors for the efficiency of global logistics operation at the construction of worldwide real time logistics information system and pursuit of the efficiency on the whole network including subcontractors. For the future competitive advantage of the Korean electronics companies, the following are suggested: 1) the establishment of arranged logistics channel adjusting each company's global strategy, 2) the construction of worldwide real time logistics information system, 3) the reengineering of all logistics procedures such as order processing, shipping, inventory control, etc., 4) the enhancement of the ratio of the supply from the external companies and the internal manufacturing subsidiaries at each continent, 5) and the pursuit of operational internalization of external subcontractors.

• Transactions of the Korean hydrogen and new energy society
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• v.23 no.1
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• pp.49-55
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• 2012

Hydrogen isotopes accountancy and storage are important functions in a nuclear fusion fuel cycle. The hydrogen isotopes are safely stored in metal hydride beds. The tritium inventory of the bed is determined from the decay heat of tritium. The decay heat is measured by circulating helium through the metal hydride bed and measuring the resultant temperature increase of the helium flow. We are reporting our preliminary experimental results on the hydrogen isotopes accountancy and storage performance in a metal hydride bed.

• Journal of the Korean Operations Research and Management Science Society
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• v.14 no.2
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• pp.67-74
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• 1989

This paper considers single-product production and inventory management problem where cumulative demands up to each time period are mutually independent random variables(known) having continuous probability distributions and the associated cost-minimizing production schedule (when to produce and how much to produce) need be determined in rolling horizon environment. For the problem, both the production cost and the inventory holding and backlogging costs are included in the whole system cost. The probability distributions of these costs are expressed in terms of random demands, and utilized to exploit a solution procedure for a production schedule which minimizes the expected unit time system cost and also reduces the probability of rist that, for the first-period of each production cycle (rolling horizon), the cost of the "production" option will exceed that of the "non-production" one. Numerical examples are presented for the solution procedure illustration.cedure illustration.

• Journal of the Korean Operations Research and Management Science Society
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• v.21 no.2
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• pp.95-109
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• 1996

In automobile industry, the depot (distribution center) system is utilized to adjust the inventory and to supply the demands to the firm timely. In case of the small lot demands of short delivery cycle and the long distance from the parts manufacturing to the firm, the depot system is very important. In this paper, a model to minimize the sum of costs of holding, inventory and transportation, is proposed to determine the optimal quantities of production and transportation in JTT system. Finally, computational results that verify the effectiveness of the proposed model are demonstrated.

• Korean Journal of Soil Science and Fertilizer
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• v.43 no.2
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• pp.237-241
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• 2010

Many policies have been implemented to mitigate the greenhouse gases in atmosphere overall of sectors. With considering the distinct characteristics of the food security, agricultural sector is no exception to this situation. To this regard, total amount of carbon which is emitted through all of the agricultural production process is calculated, and being based on this result, the demand for the introduction of agricultural production system with low carbon has been rising. Case studies on the application of life cycle assessment (LCA) technique to agricultural sector are found in many countries. For example, life cycle inventory (LCI) data bases of crop, farm infrastructure, fertilizer, farm machinery, and etc., have been constructed and provided by Ecoinvent (Swiss centre for life cycle inventories) of Swiss. In Japan, Top-down typed LCA methodology for agriculture is developed based on the inter-industry analysis, and is evaluated according to the productive method of crop. On the other hand, environmental impact assessment of agricultural system using LCA in Korea is just in the beginning stages. So it is required to assess environmental impact on agricultural fertilizer and pesticide, and to develop their flow modeling, and methodology of LCA of agricultural sector. Environmental impact assessment on agricultural materials, machinery, and infrastructure will also be carried out.

• Journal of the Korea Organic Resources Recycling Association
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• v.21 no.3
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• pp.64-73
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• 2013

The application of the Life Cycle Assessment (LCA) methodology to analyze the environmental impact to different swine waste treatment systems was investigated. The first part of LCA is to organize an inventory of parameters and emissions released due to the system under investigation. In the following step of the Life Cycle Impact Assessment, the inventory data were analyzed and aggregated in order to finally get one index representing the total environmental burden. For the Life Cycle Impact Assessment (LCIA) the Eco-indicator 95 method has been chosen because this is well documented and regularly applied impact method. Two different swine waste treatment systems such as aerobic and anaerobic digestion systems were chosen as an example for the life cycle impact analysis. For establishing the parameters to be assessed the agricultural environmental effects to above swine waste treatment systems, it has been observed that there was high at T-P emission in anaerobic digestion system and $CO_2$ emission in aerobic digestion system. For Eco-indicator values per environmental effect for swine waste treatment systems related to one tonne of swine waste, it was shown that there was a negative index for global warm potential and soil acidification in aerobic digestion system, but relatively high positive index for eutrophication in anaerobic digestion system.