• 산업경영시스템학회지
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• 제25권5호
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• pp.9-14
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• 2002

A capital investment problem is essentially one of determining whether the anticipated cash inflows from a proposed project are sufficiently attractive to invest funds in the project. The net present value(NPV) criterion and internal rate of return(IRR) criterion are widely used as means of making investment decisions. A positive NPV means the equivalent worth of the inflows is greater than the equivalent worth of outflows, so, the project makes profit. Business people are familiar with rates of return because they all borrow money to finance ventures, even if the money they borrow is their own. Thus they are apt to use the IRR in preference to the NPV. The IRR can be defined as the discount rate that causes the net present value of a cash flow to equal zero. Why the project are accepted if the project's IRR is greater than the investor's minimum attractive rate of return\ulcorner Against the NPV, the definition cannot distinctly explain the concept of the IRR as decision criterion. We present a new definition of the IRR as the ratio of profit on the invested capital.

• 전기학회논문지
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• 제66권5호
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• pp.877-884
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• 2017

A method of common earth, which is proposed by French Railway(SNCF) and is applied to high speed railway, minimizes the effect of the traction return current from tracks so that trackside electric devices can be protected and operation and maintenance staffs are kept out from injury in an electric railway environment. According to it, all the new domestic electric railway lines are replaced from existing individual earth method to the common earth method. In this paper, we analyze the correlation between common earth method and traction return current to prove whether the common earth has surely contributed to minimize the effect of the traction return current. The analysis was done based on the measurement of the traction return current at the domestic high speed railway line.

• 해양환경안전학회지
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• 제28권4호
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• pp.477-487
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• 2022

본 연구는 해양레저 분야로 귀어·귀촌한 청장년층들이 겪는 현실적인 문제점을 분석하여 해양레저산업을 통한 귀어·귀촌 활성화 방안을 제시하고자 수행되었다. 해양레저 귀촌인이 겪는 문제점과 해양레저 귀어·귀촌을 활성화 할 수 있는 방안은 무엇인가?라는 연구 문제를 해결하기 위해 질적연구방법 중의 하나인 사례연구를 통해 연구가 수행되었다. 면담 대상자는 해양레저 귀촌인과 관련 분야 전문가를 선정하였다. 그 결과 도출된 문제점은 다음과 같다. 첫째, 어촌의 배타적 문화로 발생하는 어려움. 둘째, 초기 투자비용 마련의 어려움. 셋째, 해양레저 귀어·귀촌 교육프로그램의 부족으로 나타났다. 이러한 문제를 해결하고, 해양레저산업을 통한 귀어·귀촌 활성화를 위해 제시된 방안은 다음과 같다. 첫째, 인센티브제도 도입을 통한 어촌 진입장벽 완화. 둘째, 귀어·귀촌 종합센터의 매칭 시스템 구축. 셋째, 어촌의 유휴부지를 활용한 귀어·귀촌 촉진. 넷째, 어촌계의 선 투자 후 위탁운영 시스템 도입. 다섯째, 수산 분야 교육이 포함된 해양레저 귀어·귀촌 교육프로그램 구축. 여섯째, 해양레저 귀어·귀촌 인프라 구축으로 나타났다.

• 한국환경복원기술학회지
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• 제13권3호
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• pp.63-72
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• 2010

This study was conducted to investigate the current status and the improvement plans of the ecosystem conservation fund return projects. In 2007, there was a reformation of the ecosystem conservation fund system but the fund return projects were not vitalized up until now. In this study, 35 of ongoing and finished fund return projects were investigated on their types, sites, costs, local governments, and time required to return the fund. Through the on-site survey of 9 finished projects (4 biotope, 2 corridor and 3 natural conservation facility projects), construction and management conditions were investigated. The main findings are as follows: Among the five fund return types, 17 cases were biotope restoration projects, 4 cases were ecological corridor projects, and 1 case was a nature replacement project. In the case of project sites, there were 14 cases near schools and public facilities, 8 cases near rivers or streams, and 2 cases near ponds or wetlands. For the construction costs, there were 19 cases (65% of all the projects) that cost less than 300 million won. In terms of the involvement of the local government, most of the fund return projects were concentrated in Gyeonggi province and Ulsan city, and there were some local governments outside of these regions that did not carry out any return projects at all. Lastly, in the case of fund return time required, 35% of the fund returns were completed within 5 months, but the overall average fund return time was 9.8 months. In respond to the above study results, the improvement plans to encourage fund return projects are as follows: To diversify return types and sites, piloting and modeling projects for the representative types and sites should be preceded. To emerge from customary small-scaled projects, incentives to encourage large-scale and ecological networking projects should be considered. In addition, in order to write up business plans for the fund return projects, long-term investigations of at least 2 seasons from spring to fall are necessary. Finally, for the continuous management and maintenance of the ecological fund return sites, easier way for the citizens to actively participate in the projects should be incorporated.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2006년도 하계학술발표대회 논문집
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• pp.245-251
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• 2006

The main idea of this study is to turn attention on the question of good cooling ability of customer substations in large district heating networks. The main reason for that is based on our experience that the optimization of district heating very often is directed toward production, whereas questions of optimal distribution are neglected if only the necessary load can be supplied and the customer's request for comfort is met. Our view is that low return temperature(operational temperature differences, ${\Delta}T$) in district heating systems is an Important feature for efficient net operation and gives both economic and operational benefits to the district heating supplier Furthermore, it is as well a prerequisite for meeting the customers demand for reliable supply of the heat load. However, in many practical cases we have seen that district heating return temperatures are higher than necessary. Hence, the aim of the study is to propose and verify a method for detection of the most critical consumers of the net and to identify the reasons for resulting high return temperature. From the results, temperature control system is presented as one of the most important reason of high return temperature in DH networks.

• 디지털융복합연구
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• 제20권2호
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• pp.21-35
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• 2022

본 논문은 정부 R&D 지원 중소기업의 사회 환원 실행에 영향을 미칠 수 있는 잠재적 다차원 결정요인을 규명하고자 하였다. 이를 위해 중소기업 310개 사업체를 대상으로 사회 환원에 관한 설문조사를 실시하고, 구조방정식모형을 적용하여 이와 관련한 주요 요인 간의 관계를 검토하였다. 주요 결과에 따르면 정부 R&D 지원 중소기업의 사회 환원에 대한 대중적 인식 수준이나 중소기업의 의지는 어느 정도 갖추어졌지만 사회 환원의 실행을 위한 중소기업 내부의 문화나 시스템은 상대적으로 미흡한 상황임을 보여주고 있으며, 이는 중소기업의 사회 환원 내부시스템 구축에 정책적 조준이 우선되어야 함을 의미한다. 또한, 정부의 사회 환원 정책은 중소기업의 사회 환원 의사에 영향을 미칠 수 있도록 정책 전달 장치를 보완하여야 하고, 중소기업의 사회 환원 활성화를 위해서는 중소기업의 성장이 선행되어야 한다는 점에 주목해야 함을 시사한다.

• 대한의용생체공학회:의공학회지
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• 제34권4호
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• pp.170-176
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• 2013

Lymphedema is a phenomenon in which fluid is accumulated inside tissues due to the damaged lymphatic systems. Lymphedema can cause complications such as lymphangitis, infection, changes in skin texture, fibrosis, and lymphangiosarcoma. In this study, a lymphedema screening system based on the elasticity of the skin is proposed to easily quantify lymphedema. The developed probe consists of touch sensors, a load cell and hall-effect sensors to measure the indentation force on the skin and the return time of the skin. The developed system can be used to estimate the change in the elasticity of the skin to quantify lymphedema. The system was tested with a thyroid phantom and gelatin phantoms of different concentrations and the resulting force and the time were recorded. It was found that the increase in the elasticity leads to a higher indentation force and shorter return time. This shows that the developed system can monitor the change in the skin elasticity by measuring the return time and the indentation force. The feasibility of the system in clinical applications will be evaluated in the future study.

• 한국기계가공학회지
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• 제5권2호
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• pp.49-55
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• 2006

In the consideration of the problem occurred by certain return bender brazing welding works that depend only on handworks, the automatization of the whole production line is impossible due to the high dependency of skillful workers. In addition, it is difficult to establish a standardization due to the various heat exchanger model and irregular amount of orders, and the fault reduction is also impossible due to the severe difference in brazing conditions. It is necessary to develop a method, which quantitively analyzes the problem existed in this manual brazing welding of return benders and technically solves that problem, and to lead the improvement of the productivity and cost reduction in order to increase the business competitive power. Then, this will contribute the technical development of automatic welding for Korea's heat exchanger businesses. Thus, this study develops an automatic technology, which automatically controls the flame strength using digital control methods, for various models and produces a sample model. It is possible to increase the productivity and produce uniformed and qualified products by solving the problem existed in manual processes using the developed automatic return bender brazing system. In addition, the brazing condition can be automatically controlled according to the model and line speed, and such an economical operation can reduce the production cost. The developed system is expected to future applications not only heat exchangers in the field of refrigeration and air conditioning, but also other various industrial fields that apply heat exchangers, such as car and boiler industries.

• 한국물환경학회지
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• 제22권5호
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• pp.905-912
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• 2006

In this paper, simulation methods of the system dynamics model developed by Das et al. (1997) for activated-sludge wastewater treatment plants are illustrated in an attempt to determine the operating rules and the policies related to capacity expansion of an activated-sludge wastewater treatment plant. For existing conditions, the analyses were performed by varying activated-sludge return rate to observe changes in effluent water quality and treatment efficiency. The effluent water quality is also analyzed for various average daily inflow conditions and activated-sludge return rates. As a result, without expanding the aeration tank, maximum average daily inflow that can satisfy the effluent water quality standard of BOD $0.02kg/m^3$ was determined as $2,840m^3/hr$, subject to 100% of activated-sludge return rate while other factors remain constant. When the activated-sludge return rate is less than 100%, expansion of the aeration tank is necessary and minimum sizes of the aeration tank to satisfy the effluent water quality standard were determined for various activated-sludge return rates. In addition, the total operating and maintenance as well as unit treatment cost regression equations for activated-sludge wastewater treatment plants are suggested by using the cost data that are obtained from Water and Wastewater Division, Ministry of Environment. The regression analyses showed that the economies of scale phenomena exist in the operating and maintenance costs of activated-sludge wastewater treatment plants.

• 한국콘텐츠학회논문지
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• 제19권8호
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• pp.172-183
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• 2019

현대 사회는 적은 자녀만 낳아 키우는 추세이다. 그러다보니 학부모들은 자녀의 창의적 사고방식에 대해 관심이 많아지고 새로운 교육 방식을 찾기 시작하였다. 육아종합지원센터는 다양한 장난감 및 도서 대여를 통해 아동에게는 신체 및 정서적, 사회성을 향상시켜주고 부모에게는 가계 부담을 경감시켜주는 긍정적 효과를 제공하고 있다. 본 논문에서는 육아종합지원센터에서 운영하는 장난감 도서관을 효과적으로 활용할 수 있는 대여 반납 시스템을 설계하고 구축한다. 제안하는 시스템은 사용자 누구나 육아종합지원센터에서 운영하는 모든 지점의 품목을 쉽게 검색하고 대여 및 반납 내역을 관리할 수 있도록 한다. 관리자는 대여 및 반납 처리 시스템을 통해 발생하는 대여, 반납, 연체 등의 데이터를 관리하고, 이때 만들어지는 데이터들의 통계를 통해 육아종합지원센터를 효과적으로 운영할 수 있다. 또한, 아동에게는 다양한 놀이문화를 제공하고 가정에 문화적 혜택을 제공해 부모의 양육 부담을 경감시킬 것을 기대한다.