• 한국IT서비스학회지
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• 제14권2호
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• pp.275-287
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• 2015

Information technology (IT) convergence have been recognized one of the key drivers in the industry perspective. Especially, IT convergence have been one of the most important innovative way for defense sector. Korea government established IT convergence policy in 2008 and have been applying it to the core industry such as automotive, shipbuilding and defense industries. Recently, the creative vitamin project has been launched. Vitamin 'D' means the way to create the value of defense industry. This research analyzes and evaluates various IT convergence business models based on an operation of defense IT convergence center from 2011 to 2014, which is the industry IT convergence centers. Defense IT convergence business models can be classified into four types of mission area as follows : weapon acquisition and management, military intelligence, military power construction, and resources management. We define the concept of defense IT convergence and describe the framework and processes for applying IT to the defense sector. We analyzes and evaluates various business models designed through defense IT convergence framework and processes.

• Journal of Power Electronics
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• 제18권5호
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• pp.1369-1379
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• 2018

In this paper, a model predictive torque control (MPTC) without the use of a weighting factor for surface mounted permanent-magnet synchronous machine (SPMSM) drive systems is presented. Firstly, the desired voltage vector is predicted in real time according to the principles of deadbeat torque and flux control. Then the sector of this desired voltage vector is determined. The complete enumeration for testing all of the feasible voltage vectors is avoided by testing only the candidate vectors contained in the sector. This means that only two voltage vectors in the sector need to be tested for selecting the optimal voltage vector in each control period. Thus, the calculation time can be reduced when compared with the conventional enumeration method. On the other hand, a novel cost function that only includes the dq-axis voltage errors between the desired voltage and candidate voltage is designed to eliminate the weighting factor used in the conventional MPTC. Thus, the control complexity caused by the tuning of the weighting factor is effectively decreased when compared with the conventional MPTC. Simulation and experimental investigation have been carried out to verify the proposed method.

• 한국산학기술학회논문지
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• 제11권1호
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• pp.73-78
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• 2010

본 연구에서는 분산전원이 연계된 배전계통에서 발생하는 고조파를 평가하고자 PSCAD/EMTDC를 이용하여 분산전원 배전계통 연계 시의 시뮬레이션을 수행하였다. 실계통과 유사한 배전계통 및 태양광발전 시스템을 모델링하여 연계지점을 구간마다 시뮬레이션을 수행하였다. 고조파 연계기준(IEEE Std 1547과 IEEE Std 519)을 적용하여 알고리즘을 작성하고, 시뮬레이션 데이터는 FFT로 변환하여 THD와 TDD로 구분하여 평가하였다. 구간별로 구분하여 평가한 고조파 함유량은 분산전원을 연계하지 않은 상태와 각 구간과 Case 별로 구분하여 평가하여 연계하기 전과 비교하여 고조파를 파악한 결과 모든 배전계통의 구간에서 고조파 분포가 적합하다는 평가를 할 수 있었으며, 부하로 선정한 50kW 유도모터의 특성으로 인해 구간 2에서의 고조파 분포가 증가함으로서 연구 결과의 효용성을 입증할 수 있었다.

• Current Photovoltaic Research
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• 제11권4호
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• pp.134-143
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• 2023

Efforts are being made to respond to global warming. Interest in and demand for the private sector-led RE100 campaign is also increasing. Self-built solar power generation, one of the implementation tools for RE100, is not expanding. However, it can be an economical means of implementation in the long run. In this study, we intend to analyze the impact on the optimal ratio of self-solar power generation using HOMER simulation. OPR defines the optimal solar power generation ratio and looks into what changes there are in the optimal solar power ratio when self-power consumption increases and external power purchase price changes. As a result, the optimal rate of self-solar power generation has a low impact even if self-power consumption increases. As the external power unit price increases, the optimal ratio increases, and at a power unit price of 100 KRW/kWh, OPR is 24%; at 200 KRW/kWh OPR is 31%; and at 300 KRW/kWh OPR is 34%. This shows that the electricity price replaced during the life cycle has a high impact on the economic feasibility of solar power generation. However, when the external power unit price reached a certain level, the increase in OPR decreased. This shows that it is difficult for domestic companies to achieve RE100 based on the economic feasibility of solar energy alone. Therefore, efforts are needed to supply renewable energy in the public sector.

• Journal of Biosystems Engineering
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• 제33권1호
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• pp.14-20
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• 2008

An agricultural unmanned helicopter was suggested for an alternative to current pesticide application methods to solve such problems as high cost, low efficiency, shirking task and unsafe work. To pursuit this trend, researches on the development of unmanned helicopters have been accelerated in Korea as well. In this research, a guide type centrifugal clutch that plays an important role in the unmanned helicopter was studied. Theoretical analyses and experimental tests were conducted for designing an optimal clutches. Main design factors of the guide type centrifugal clutch were found to be spring constant, free length of spring, mass of friction sector, contact area, allowable pressure, number of friction sector, friction coefficient, radius of drum, and clutch arrangement. And these design factors could be the functions of engaging engine speed and desired power transfer capacity. The result of the single clutch test showed the power transfer capacity of 14.1 PS at 5,800 rpm and the result of the dual clutch test showed that the capacity of 17.7 PS at 5,600 rpm. These experimental results agreed well the theoretical simulations.

• 자원ㆍ환경경제연구
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• 제22권1호
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• pp.77-98
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• 2013

본 논문에서는 향후 포스트 교토협약에서 온실가스 감축의무국으로 분류될 가능성이 높은 세계 최대의 $CO_2$ 배출국 중국의 화력발전산업을 대상으로 Shephard 투입물거리함수를 추정하여 $CO_2$ 암묵가격과 기술효율성, 그리고 투입요소 간 간접 모리시마 대체탄력성을 측정한다. 1981-2009년 기간 동안 $CO_2$ 1톤을 감축하는 데 연간 평균 약 3.2달러의 비용이 드는 것으로 나타났다. 이는 한국, 일본의 발전 산업에 대한 $CO_2$ 암묵가격 추정치보다 낮은 수준으로서 향후 이들 나라와 배출권 거래가 이루어질 경우 배출권 판매를 통한 경제적 이득이 예상된다. 기술효율성의 향상으로 달성할 수 있는 최대 $CO_2$ 잠재 감축량은 연간 평균 약 2천 5백만톤에 이르는 것으로 산정되었다. 석탄과 석유 등의 연료와 자본은 상호 대체가능하며 자본이 연료를 더 용이하게 대체하는 것으로 나타났다.

• 한국태양광발전학회지
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• 제6권1호
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• pp.45-55
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• 2020

Although Sri Lanka's current carbon footprint is much less compared to other developing countries, the country's existing and planned economic developments have raised the demand for power, resulting an increased GHG (Greenhouse gas) emission. GHG in Sri Lanka is emitted mostly by the burning of fossil fuels for energy generation including transport. However, the most effective way of reducing GHG emissions from the energy sector is to use renewable energy sources. Solar is in the top list of renewable resources that has much potential to use to meet the demand for electricity generation in the country. The purpose of this study is to evaluate the current status of solar power generation and opportunities, barriers for implementing the programs of solar energy in Sri Lanka. Literature reviews mainly used as the primary tool for this study. Sri Lankan government had set the targets for adding 200 MW to the national grid by 2020, and to increase up to 1000 MW by 2025 of solar electricity. To achieve these targets the prevailing barriers have to be considered.

• Wind and Structures
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• 제27권2호
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• pp.111-121
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• 2018

Experiments were conducted in a large-scale Ward-type tornado simulator to study tornado-like vortices. Both flow velocities and the pressures at the surface beneath the vortices were measured. An interpretation of these measurements enabled an assessment of the mean flow field as well as the mean and fluctuating characteristics of the surface pressure deficit, which is a manifestation of the flow fluctuation aloft. An emphasis was placed on the effect of the aspect ratio of the tornado simulator on the characteristics of the simulated flow and the corresponding surface pressure deficit, especially the evolution of these characteristics due to the transition of the flow from a single-celled vortex to a two-celled vortex with increasing swirl ratio.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 추계학술대회 논문집 전력기술부문
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• pp.266-268
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• 2004

This paper presents the greenhouse gas emission trading scheme which is under progress as a pilot project at the power sector in preparation for UNFCCC. By referring UK's, Emission Trading is introduced incentive auction to maximize the reduction of greenhouse gas emission. At the 1st step, from year 2006 to 2008, only CO2 is regarded as an objective target to decrease but emission credit is excluded with an assumption and only 5 Generation company take part in as participants. The market operating procedure is composed of participants' registration, baseline verification, incentive auction, the registration of initial and yearly allocation, emission trading, yearly emission verification & approval, yearly obligation conformity, carry forward & incentive grant. It can be serve a guideline the whole aspects of emission trading which will start in 2006 including operation, verification and profit sharing.

• 국제학술발표논문집
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• The 1th International Conference on Construction Engineering and Project Management
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• pp.824-829
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• 2005

This paper focuses on construction cost volatility for the purpose of private sector investment by use of a financial model with key indices of IRR and DSCR (Debt Service Coverage Ratio). A case project, 1,000 MW pumped storage hydropower plant, has shown that its financial impacts by cost volatility of underground works are less measured than interest rates impacts by interest rate of loans. Probabilistic analysis of costs under geotechnical conditions has been made by Indicator Kriging method. And, in the modeling of interest rates, geometric Brownian motion has been applied. Both of these impacts are measured on the same financial model.