• 한국산업융합학회 논문집
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• 제25권3호
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• pp.333-340
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• 2022

Recently, the use of large-capacity secondary batteries for electric vehicles is rapidly increasing, and accordingly, the demand for technologies and equipment for battery reliability evaluation is increasing significantly. The existing short circuit test equipment for evaluating the stability of the existing secondary battery consists of relays, MCs, and switches, so when a large current is energized during a short circuit, contact fusion failures occur frequently, resulting in high equipment maintenance and repair costs. There was a disadvantage that repeated testing was impossible. In this paper, we developed an electronic short circuit test device that realizes stable switching operation when a large-capacity power semiconductor switch is energized with a large current, and applied smart ICT technology to this electronic short circuit stability test system to achieve high speed and high precision through communication with the master. It is expected that the inspection history management system based on data measurement, database format and user interface will be utilized as essential inspection process equipment.

• 국제학술발표논문집
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• The 2th International Conference on Construction Engineering and Project Management
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• pp.509-519
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• 2007

Private financing is playing an increasing role in public infrastructure construction projects worldwide. However, private investors/operators are exposed to the financial risk of low profitability due to the inaccurate estimation of facility demand, operation income, maintenance costs, etc. From the operator's perspective, a sound and thorough financial feasibility study is required to establish the appropriate capital structure of a project. Operators tend to reduce the equity amount to minimize the level of risk exposure, while creditors persist to raise it, in an attempt to secure a sufficient level of financial involvement from the operators. Therefore, it is important for creditors and operators to reach an agreement for a balanced capital structure that synthetically considers both profitability and repayment capacity. This paper presents an optimal capital structure model for successful private infrastructure investment. This model finds the optimized point where the profitability is balanced with the repayment capacity, with the use of the concept of utility function and multi-objective GA (Generic Algorithm)-based optimization. A case study is presented to show the validity of the model and its verification. The research conclusions provide a proper capital structure for privately-financed infrastructure projects through a proposed multi-objective model.

• 산업공학
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• 제10권1호
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• pp.237-248
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• 1997

The purpose of this study is to make an economic analysis of power plant utilities by examining electricity generating costs with environmental consideration. Economic growth has caused pollutant emission, and subsequent environmental pollution has been identified as a very real limit to sustainable development. Considering the enormous role of electricity in the national economy, it is thus very important to study the effect of environmental regulations on the electricity sector. Because power utilities need large investments during construction, operation and maintenance, and also require much construction lead time. Economic analysis is the very important process in the electric system expansion planning. In this study, the levelized generation cost method is used in comparing economic analysis of power plant utilities. Among the pollutants discharged of the electricity sector, this study principally deals with the control activities related only to $CO_2$, and $NO_2$, since the control cost of $SO_2$, and TSP (Total Suspended Particulates) is already included in the construction cost of utilities. The cost of electricity generation in a coal-fired power plant is compared with one in an LNG combined cycle power plant. Moreover this study surveys the sensitivity of fuel price, interest rate and carbon tax. In each case, this sensitivity can help to decide which utility is economically justified in the circumstance of environmental regulations.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2022년도 추계학술대회
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• pp.204-206
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• 2022

스마트 팩토리(Smart Factory) 고도화의 핵심으로 평가되는 디지털 트윈(Digital Twin)은 현실 세계의 자산과 동일한 속성 및 기능을 가지는 디지털 복제본을 가상의 세계에 구현하는 기술이다. 디지털 트윈 기술이 적용된 스마트팩토리는 생산공정의 실시간 모니터링, 생산공정 시뮬레이션, 생산설비 예지보전 등의 서비스를 지원할 수 있어 생산비용 절감 및 생산성 향상에 기여할 것으로 기대된다. AAS(Asset Administration Shell)는 디지털 트윈을 구현하기 위한 필수 기술로, 현실의 물리적 자산을 디지털로 표현하는 방법을 제공한다. 본 논문에서는 스마트팩토리 내 생산설비를 자산으로 간주하여, 운용 중인 실시간 CNC(Computer Numerical Control) 모니터링 시스템에서 활용할 제조 데이터 수집을 위한 AAS를 설계하였다.

• 풍력에너지저널
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• 제13권3호
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• pp.43-52
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• 2022

Although wind turbines have obtained type certification according to international standards and are released to the market, they cannot be regarded as design evaluations that consider site characteristics. Therefore, it is necessary to study the site-specific load analysis method based on the meteorological data measured at the candidate site. In this study, site-specific load calculation was performed based on the meteorological data from the Jeju Haengwon mast. Analysis results were compared and analyzed with the results calculated by IEC design Class (IIA). For the fatigue loads at the blade root and tower base, the site-specific condition was lower than the IEC IIA, but in the case of the ultimate load, the site-specific condition showed higher results in some design load cases (DLCs). Selecting a wind turbine suitable for a site through load evaluation considering site conditions can prevent the reduction of operation and maintenance (O&M) costs and the power loss caused by downtime. Finally, it is expected to contribute to the project's levelized cost of energy (LCOE) reduction.

• 농업과학연구
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• 제29권2호
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• pp.135-148
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• 2002

In recent years, domestic market environment of rice production is confronted with the problems of excessive production and decrease in per capita consumption, resulting in steady decline of domestic rice price. Moreover, as new trade negotiations of WTO or FTA are being forwarded, cheap price of imported rice will also make the rice production environment being worse off. One of the possible production strategies to relieve this situation could be expanding farm size, which increases market competitiveness in terms of cost-saving. Since 1990's, one of the main agricultural policies for rice production in Korea has been expanding farm size. This study aims at 1)exploring brief history of Korean government's agricultural policy for expanding farm size, 2)examining economic effect of farming size expansion, and 3)discussing major role of government to promote appropriate programs for rice-farming and producers. Main conclusion suggests that appropriate farming size should be expanded upto at least five hectares per farm, with producers' effort to reduce farming costs and continuous investments on agricultural infrastructures including irrigation systems, etc. Continuous government's investment on operation and maintenance on water facility is also one of the important factors in expanding farm size.

• 한국안전학회지
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• 제32권6호
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• pp.40-45
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• 2017

Chemical accidents generated during maintenance, repair, and normal operation, such as dispersion, fire, and explosions, can cause massive losses like a 2012 hydro fluorine leak in Gumi, South Korea. Since this accident, many researches have studied physical mitigation systems. However, due to many difficulties including potential costs and lack time, it is really hard for many companies to install mitigation systems without prior knowledge. Thus, the efficacy of mitigation system should be evaluated. This study assesses a dike design considering the fluid velocity at an open hole when a leakage accident occurs. It is assumed that leakage materials follow a free fall motion. Throughout case studies, a current KOSHA guide for a dike design was evaluated and new guidelines handling various conditions were proposed.

• 한국건설관리학회:학술대회논문집
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• 한국건설관리학회 2004년도 제5회 정기학술발표대회 논문집
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• pp.13-19
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• 2004

민자사업의 사업관리주체는 몇몇 사업을 제외하고는 해당 사업의 시행을 위해서 별도로 설립된 사업시행법인인 경우가 대부분이다. 본 연구에서는 민자사업의 사업관리사례로서 사업시행법인 자체의 조직과 인력을 활용한 발주자CM의 형태로 사업관리를 수행한 서울외곽순환(일산$\~$퇴계원)고속도로 민자사업의 사례를 분석, 제시하고자 하였다. 시간관리의 측면에서 사업시행법인은 시공단계의 단순한 공정관리 틀에서 벗어나 사업의 계획. 설계, 인허가, 시공, 그리고 운영 및 유지관리까지 사업 전단계에 걸친 사업관리주체라는 관전으로 접근하였으며, 비용관리의 측면에서 시공단계의 사업비 증파에 대한 risk의 부담주체는 민간이라는 기본 전제하에 설계VE 등을 통한 사업비 절감요인 도출 등 보다 적극적인 사업비 관리가 요구되었다.

• 조명전기설비학회논문지
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• 제25권5호
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• pp.7-14
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• 2011

Currently high power Light Emitting Diode (LED) is in the limelight due to its characteristics of long durability, low maintenance costs, and high efficiency. Furthermore, it does not emit pollutants or poisonous gases and is a light source not using mercury, so it holds a high status in eco-friendly terms as well. In this paper, we studied a two-stage LED power drive circuit that can compensate only voltage regulation through LED output current, in order to improve efficiency of LED drive with constant current control in accordance with changes in temperature. The proposed LED drive has an advantage of reducing LED drive's voltage losses by controlling only voltage change of input power, compared with an existing circuit which controls input voltage. The suggested non-insulation compensating circuit for voltage change was verified to have improved efficiency relative to a LED drive using existing DC/DC converter.

• 한국조경학회지
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• 제36권6호
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• pp.34-42
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• 2009

본 연구는 공동주택 단지에 온실 형태의 EVERGREEN PARK를 도입하기 위하여 진행하였으며, 단순한 관상을 위한 온실이 아닌, 주민의 적극적인 참여와 활용을 목표로, 사계절 내내 이용 가능한 외부 공간의 구심점으로서 주민의 편의와 유익한 서비스를 제공하고자 하였다. 계획의 주안점은 다음과 같다. 첫째, 아열대 식물들은 상록활엽성 식물들로 사계절 녹음을 유지하고, 잎의 육질이 두껍고 윤택이 많다. 이런 상록활엽수들이 주 수종인 아열대 식물용 온실을 온대지방에 도입하여 독특하고 고급스런 상록수림을 온대지방 사람들이 이용할 수 있도록 계획하였으며, 최고급의 상록식물상을 매우 저렴한 유지관리 비용으로 이용자들에게 제공할 수 있도록 계획하였다. 둘째, 공동주택단지 내에 도입한 아열대 식물용 온실은 지하연계구조형과 독립 구조형으로서 가온설비 없이 조성하여 지열을 이용하며, 차광 등의 방법을 이용하도록 제시하였다. 셋째, 활용방안으로서 (1) 건강과 휴식(Evergreens, 허브가든, 수 공간), (2) Community와 교육(식물벼룩시장 및 식물병원, 식물관련강좌(전시회), 체험학습프로그램), (3) Vine Garden 등의 운영프로그램을 제시하였으며, 나비축제, Aroma festival, Smile Oak Nuts, 촛불축제, Christmas! Photo Site 등의 4계절 이용방안을 제시하였다. 넷째, 온실의 운영 유지관리는 주민이 중심이 되는 주민차치회 중심 운영관리와 외부전문업체 중심 운영관리의 방안을 제시하였다.