• 소음진동
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• 제11권2호
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• pp.257-264
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• 2001

In this research, piezoelectric smart structures are applied for SEA(Statistical Energy Analysis), which is well known approach for high frequency analysis. A new input power measurement based on piezoelectric electrical power measurement is proposed and compared with the conventional method in SEA. As an example, a simple aluminum beam on which piezoelectric actuator is attached is considered. By measuring the electrical impedance and electrical current of the piezoelectric actuator, the electrical power given on the actuator is found and this is In turn converted into the mechanical energy. From the measured value of the stored energy of the beam, the Internal loss factor is calculated and this value shows a good agreement with that given by the conventional method as well as the theoretical value. To compare the coupling loss factor, L-shape beam system which consists of a aluminum beam subsystem and a steel beam subsystem coupled by three pin is taken as second example. The input power and stored energy of each subsystem are found by the proposed approach. The coupling loss factor found by the electrical input power obtained from the piezoelectric actuator exhibits similar trend to the value found by the conventional method as well as the theoretical value. In conclusion, the use of SEA for high frequency application of piezoelectric smart structures is Possible. Especially, the input power that is essential for SEA can be found accurately by measuring the electrical input power of the piezoelectric actuator.

• 전기학회논문지
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• 제57권11호
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• pp.2117-2123
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• 2008

This paper describes the portal system architecture of large consumers for ESP(Energy Service Provider) to provide customers with various value added services such as monitoring and controlling a wide variety of electric devices in consumer's premises for optimal energy management from both consumer side and ESP side, and the prototype implementation of 2 kinds of value added services. The architecture is composed of the device portal which gathers the information from electric devices and controls them and the consumer portal which can make ESP operate the optimal energy management with two-way communications. The demand side management and energy management functions was chosen and implemented for the prototype system as value added services. The prototype was designed to create, manage, and trace the events about services between ESP and customers.

• 대한산업공학회지
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• 제38권2호
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• pp.144-156
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• 2012

In recent years, advanced countries in energy sector are emphasizing the importance of the development and deployment of renewable energy to cope with the global environmental crisis such as depletion of fossil energy, climate convention to control emissions of greenhouse gases. In this paper, we evaluate the economic value of the investment in new and renewable energy R&D in Korea and optimal deployment timing of new and renewable energy by using the real option approach. The real option model adopted in this paper assumes that a decision maker has a compound option to abandon, deployment, or continue the R&D. As a result by using empirical data of Korea, it is found that there exists a considerable amount of positive real option value (ROV) in the investment of new and renewable energy R&D while its net present value (NPV) calculated by traditional discounted cash flow (DCF) model shows negative value.

• Asian-Australasian Journal of Animal Sciences
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• 제2권3호
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• pp.425-426
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• 1989

• 한국자동차공학회논문집
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• 제22권7호
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• pp.70-75
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• 2014

The experiment was done on traveling at the speed of 20km/h, 60km/h and 100km/h using the performance testing mode for chassis dynamometer. The experimental method were employed to measure the waveform of secondary ignition coil and exhaust emission. In this experiment, the correlation between the secondary waveform coming from ignition coil and exhaust emission were measured in decrepit vehicle. The secondary waveform characterized by the value of effective discharge energy. The following results are obtained by analyzing the data relativity between the effective discharge energy and exhaust emission. The variation rate of effective discharge energy was largest 60km/h, 20km/h, 100km/h velocity in the ordered named. As the vehicle velocity increases, the average variation rate of CO and $NO_X$ decreases and that of HC and $CO_2$ decrease. The value of effective discharge energy, CO, $NO_X$ and fuel consumption is measured badly in case of car with failures in MAP, spark plug and good in case of car with before and after maintenance regardless of vehicle velocities. The value of effective discharge energy is to be nearly parabolic shape as vehicle velocity increases. As the value of effective discharge energy increases, the value of $NO_X$, HC and $CO_2$ decrease, the value of CO increase. The most sensible factors of exhaust emission were CO, $NO_X$, and the small variation factors were HC, $CO_2$.

• 한국태양에너지학회 논문집
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• 제25권1호
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• pp.79-86
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• 2005

The external conditions for estimating dynamic wind loads of wind turbines, such as the turbulence, the extreme wind, the mean velocity gradients and the flow angles, are simulated over GangWon Wind Energy Test Field placed in one of the most complex terrain in Korea. Reference meteorological data has been gathered at a height of 30m from 2003 to 2004 with a ultrasonic anemometer. The absolute value of the spectral energy are simulated and the verification of this prediction has been carried out with comparing to the experimental data. The most desirable place for constructing new wind turbine are resulted as Point 2 and Point 3 due to the lower value of Turbulence Intensity and the higher value of wind resource relatively.

• 한국태양에너지학회 논문집
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• 제30권4호
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• pp.49-54
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• 2010

Most energy using in building part is mainly consumed for heating and cooling to meet occupancy's comfort temperature. Generally, heating energy consumption show high value than cooling energy in Korea because of high temperature difference in winter season as compared with summer in apartment building. The efforts to develope mechanical performance have been studied to reduce energy consumption in building energy field until now. However, the energy consumption in building is impacted by not only system performance but also PMV particularly at temperature and Clo value. This means that energy consumption can be changed by occupancy's comfort setting temperature in apartment building. This study investigated the passibility of overheating in apartment building by occupant' slow Clo and its setting temperature from preceding research and then the heating energy consumption by setting temperature was calculated with ESP-r. The effects of heating energy and $CO_2$ reduction are also evaluated quantitatively with Clo value. The results showed that keeping ISO-7730 standards can reduce heating energy up to 21% in compared with option 2; also, wearing underclothes with ISO-7730 standard can considerably reduce heating energy consumption up to 50%. As compared with option 2, the reduction of $CO_2$ emission for option 3 showed 0.63TCO2 of kerosene, 0.49TCO2 of LNG and 1.09TCO2 of electricity. The option 4 can be reduced by 1.48TCO2 of kerosene, 1.16TCO2 of LNG and 2.57TCO2 of electricity respectively.

• 한국태양에너지학회 논문집
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• 제29권5호
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• pp.59-64
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• 2009

According to the building regulation U-value limitation of window is $3.3W/m^2{\cdot}K$ in southern regions, while U-value limitation of wall is $0.35{\sim}0.58W/m^2{\cdot}K$. It means that the energy loss through windows is five times more than it through wall. Therefore, this study analyze how much it has affected building energy rating when the insulation performance of windows and walls is changed by building regulation. In conclusion, in order to obtain 2 rating thermal performance of windows is improved more than 10 percent of U-value limitation and it of wall is improved more than 20 percent. The thermal performance of windows is improved more than 20 percent of U-value limitation and it of wall is improved more than 30 percent to receive 1 rating.

• 에너지공학
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• 제18권3호
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• pp.175-190
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• 2009

본 연구는 국내 태양에너지 기업의 가치사슬별 경제적 성과와 그 결정요인인 규모의 경제, 기술수준, 자금조달능력, 국내시장 경쟁정도 등간의 상관관계를 분석하고 있다. 249개 기업에 대한 설문조사를 바탕으로 다중로짓분석을 실시하였다. 분석의 결과 기업의 경제적 성과는 자금조달능력이 높을수록, 시장경쟁이 낮을수록 높았으며, 기술수준과 규모의 경제는 유의미하지 않는 것으로 분석되었다. 가치사슬별 분석에서 부품조달공정은 기술수준이 낮을수록, 자금조달능력이 높을수록, 제조공정은 기술수준 및 자금조달능력이 높을수록, 그리고 마케팅공정은 자금조달능력이 높을수록, 시장경쟁이 낮을수록 경제적 성과가 높은 것으로 나타났다. 이로써 국내 태양에너지산업은 특유의 기술혁신체제 구축, 선진화된 금융시스템 구축, 그리고 가치사슬 공정별로 핵심능력을 가진 기업 간 네트워크를 구성하여 운영하는 프랙털 시스템을 추진해야 할 것으로 전망된다.

• Journal of Advanced Marine Engineering and Technology
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• 제12권3호
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• pp.57-67
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• 1988

Although handicapped by the inability to bridge the size gap between small laboratory sample and large engineering component, the V charpy test sample method does possess certain advantages, such as each of preparation, simplicity of test method, speed, low cost in test machinery, and low cost per test. On the other hand, the COD test method does posses advantages, which reduce the size gap between the laboratory sample and actual engineering component. Consequently, the correlation between V charpy absorbed energy and the critical COD value is required for estimating critical COD value from the simple V charpy test results. In this paper, the high tensile strength steel AH36 plate specimens having a single edge cracked notch were investigated to find out the correlation between V charpy absorbed energy and critical COD value in the welded parts under such various welding methods as shielded metal arc welding, the submerged arc welding and the electro gas welding by means of V charpy impact test and static 3-point bending test. Main results obtained are as follow ; 1. The relationships between V charpy absorbed energy Wc' and critical COD value ($\delta_c$)show; $\delta_c$=0.0065 Wc'+0.1906. 2. Ductile- brittle transition behaviours can be estimated by means of fracture appearance and general yielding behaviours. 3. The V charpy absorbed energy of SMAW is higher than that of SAW, EGW and similar relationships are obtained in the COD tests.