• Environmental Sciences Bulletin of The Korean Environmental Sciences Society
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• v.10 no.S_1
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• pp.35-40
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• 2001

Effect of the addition of an enzyme/microbial additive(EMA) to enhance anaerobic digestion of the primary sludge was investigated. Two laboratory scale anaerobic digester were operated with primary sludge taken from a municipal wastewater treatment plant. The digester receiving EMA with the sludge feed performed better than the control digester, when both were operated at 10-days and 15-days Solid Retention Time(SRT). Addition of EMA to the experimental digester provided 7%(10-days SRT) and 16%(15-days SRT) higher gas production compared to the control digester when both were fed with the same amount of volatile solids. The reduction in volatile solids was 24% better in the experimental digester compared to the control ar 10-days SRT, and the improvement 10% at 15-day SRT. Improvement in COD reduction, and fecal coliform density reduction were also seen in the experimental digester due to EMA addition compared to the control both ar 10-days SRT and 15-day SRT operation. Preliminary cost benefit analysis for a wastewater treatment plant showed that approximately $115/day in gas production improvements can be realized upon addition of EMA to primary sludge anaerobic digesters operating at 10-day SRT. The value of increased gas production was $172/day if the same digesters are operated with EMA addition at 15-day SRT.

• Korean Chemical Engineering Research
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• v.46 no.3
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• pp.598-603
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• 2008

In petrochemical complex, Hydrogen Network optimization is surveying the extra Hydrogen and needed Hydrogen of each company and calculating the optimized distribution. This paper compares the case of using the existing pipeline and the case of not using the existing pipeline to show the effect quantitatively and clearly by modeling the both cases and using mathematical programming. As a result, using the existing pipeline can save the pipe cost over 20% and increase the whole network benefit by thirteen billion won.

• Journal of the Ergonomics Society of Korea
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• v.17 no.1
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• pp.47-54
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• 1998

Product design and development is very important process in enterprise activities. Reducing development time and reflecting consumer's needs is required to product design and development for increasing benefit and decreasing cost. Human sensibility ergonomics is one of the important technology of R&D in product development. However, the subjective method of human sensibility ergonomics has several problems to analyze and to Quantify experimental data and objective method of human sensibility ergonomics is still in process on study. In this research, new analyzing method is proposed for the subjective human sensibility ergonomics applied with fuzzy set theory. What is the useful theory for controlling uncertain type of information like human mind? This approach is more effective method for analyzing consumer's needs for product design and development process. At collecting needs, certainty scale is added for adapting hedge of fuzzy function. Using a kind of union operator, synthesize each item to analyze identification of each item with fuzzy hamming distance. Identification of analysis is classified with the relational weight using Relationship Chart Method, and is drawn the relationship diagram for clustering each item. A case study with sample test is conducted and demonstrated with this suggested method for more effective way.

• Proceedings of the Korean Society of Medical Physics Conference
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• 2002.09a
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• pp.305-308
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• 2002

More complex radiotherapy techniques using multi leaf collimation(MLC) such as intensity-modulated radiation therapy(IMRT) has been increasing the significance of verification of leaf position and motion. Due to the reliability and robustness, quality assurance(QA) of MLC is usually performed with portal films. However, the advantage of ease of use and capability of providing digital data of electronic portal imaging devices(EPIDs) have attracted many attentions as alternatives of films for routine quality assurance in spite of the concerns about their clinical feasibility, efficacy, and the cost to benefit ratio. In our work, the method of routine QA of MLC using electronic portal imaging(EPI) was developed. The verification of availability of EPI images for routine QA was performed by comparison with those of the portal films which were simultaneously obtained when radiation was delivered and known prescription input to MLC controller. Specially designed test patterns of dynamic MLC were applied to image acquisition. Quantitative off-line analysis using edge detection algorithm enhanced the verification procedure in addition to on-line qualitative visual assessment. In conclusion, the EPI is available enough for routine QA with the accuracy of portal films.

• Journal of Forest and Environmental Science
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• v.25 no.1
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• pp.35-41
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• 2009

Agroforestry combines agriculture and forestry technologies to create more integrated, diverse, productive, profitable, healthy and sustainable land-use systems. This study was performed in three union of Chhagalnaiya Upazila (Sub-district; administrative entity) under Feni district, Southern Bangladesh with a view to identify the tree resources, utilization pattern and economic return of major fruit and timber tree species. Information collected from a total of 45 households ranging from marginal, small, medium and large categories. Number of plant species increased with the increase of homestead area. A total of 39 plant species were recorded from the homegarden, of which 23 were fruit and 16 were timber tree species. Considerable number of vegetables was also planted under the shade of the homestead trees. The investment analysis showed that average benefit-cost ratios were greater than one, net present values were positive and internal rate of returns were more than 10%. Long term investment on horticulture and timber tree species is highly profitable if species like Swietenia mahagoni and Tectona grandis, Spondias pinnata, Syzygium cumini and Areca catechu were planted.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.6
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• pp.797-803
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• 2012

In this paper, for minimizing the real-time operating load losses of the power transformer, a SCADA optimum operating system was developed, and the economic analyses on the test operation were performed. Transformer loss DB which reflects the economic integration operation criteria was constructed by referring the transformer manufacturer's loss data(iron loss, copper loss). Based on the loss DB, each substation transformer real-time loss was calculated according to the size of the transformer loads, and if integration or separation transformer operating conditions minimizing the loss are met, then a window pops-up and the dispatcher performs the substation equipments operation according to the procedure provided by this system. With the existing SCADA main program, the relation database of the substation facilities and integration/separation operation algorithm were developed and applied to Auto MTR Processor and pconn Processor Task module. Seven stations test data for seven months were analyzed for the economic analyses, and the results showed that Cost-Benefit ratio was 2.64, and IRR(Internal Rate of Return), 36%, which asserted the economic justification of the proposed system.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2003.10a
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• pp.565-568
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• 2003

Optical fiber is a kind of local loop types. Most of countries do not still require the incumbent to open his optical fiber network except just a few countries such as US, Japan and Italy. Recently the FCC, the regulator in US, decided to reduce the obligation of its unbundling in order to facilitate the incentive of broadband network investment. And Japan also is reviewing the policy of the fiber' unbundling. So, We needs to take into consideration about the benefit and cost of the opening of optical fiber network in advance. The purpose of this paper is to review the opening policy of optical fiber network in Japan, and to discuss the implication of case study.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.51 no.6
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• pp.290-295
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• 2002

The present assignment in installing the number of switches for distribution line was made on the basis of a normal feeder capacity 7,000kVA in KEPCO(Korea Electric Power Corporation), Korea. But the normal capacity is revised to 10000kVA in 1998. Even increasing limit of the operating capacity of the distribution lines enables us to give some benefit for the operation flexibility and investment cost of the distribution system. It is disadvantageous in the viewpoint of supply reliability. In distribution systems, switches are equipped to improve the reliability of distribution systems by minimizing the outage section due to fault and maintenance. Utility generally improves the reliability by minimizing the length of outage section, which is caused by fault and maintenance, through switch equipment on distribution system. In order to cope with the changes such as operation capacity, it is necessary to study whether the present criteria is reasonable or not, also to confirm whether the present criteria of installing switches in line is improved or not. In this study, we proposes the number of switch per feeder on the basis of present operation capacity in distribution system.

• The Korean Journal of Health Service Management
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• v.7 no.4
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• pp.273-288
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• 2013

This paper is a general review contextualizing the state of the domestic health technology assessment. The aim of the paper is to present an overview of health technology assessment in Korea based on examining clinical efficacy as well as cost-benefit analysis, and to suggest the issue of appraisal based on social value. We have included a discussion of a major case study of the technology appraisal process of NICE (the National Institute for Clinical Excellence) in the UK. The review of the existing process of NICE shows that the appraisal both gives interest in health technology a sense of value perspective and raises methodological issues in terms of reliability. Details of the appraisal process and several guidelines for best practice have emerged. Suggestions are listed and their role in assessing is explained as a conclusion.

• Transactions of the Korean Society of Automotive Engineers
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• v.24 no.6
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• pp.709-715
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• 2016

This paper presents a comparison of an experimental study on spot and plug welding of an automotive body panel. Spot welding is a common joining technology used in automotive body panel assembly. In automotive body repair, however, plug welding is widely used due to its technical simplicity and cost benefit. Some researchers have focused on the use of spot welding in the manufacturing process, but there has been very little research done with respect to the engineering analysis of the plug welding process. In this study, two kinds of specimens are considered to compare the difference of failure strength between spot weld and plug weld: normal tension and shear tension. The experimental results show, in both normal tension and shear tension, that spot welding has higher failure strength than plug welding. In addition, plug welding is more vulnerable to shear tension than normal tension. This study can be applied to further studies on practical optimization for maintenance and repair of automotive body panels.