• Elastomers and Composites
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• v.37 no.3
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• pp.151-158
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• 2002

An elastomeric bushing which has been considered in this research is a device used in automotive suspension systems to reduce the forte transmitted iron the wheel to the frame of the vehicle. A bushing is modeled at a hollow cylinder which is bonded to a solid metal shaft at its inner surface and a metal sleeve at its outer surface. Lianis constitutive equation for a nonlinear viscoelastic incompressible material is used to model the elastomeric material of the bushing. It is used to derive a force-displacement relation for axial response of the bushing. The displacement dependent force relaxation function for the bushing is obtained from the ramp displacement control tests with an extrapolation method. This is compared with the exact result obtained from the step displacement control test and the results are in very good agreement.

• Proceedings of the Korea Information Processing Society Conference
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• 2018.10a
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• pp.928-931
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• 2018

고립된 해상 작업 환경에서의 작업자의 건강상태 관리와 혹시 모를 추락탐지는 작업자의 안전을 위해 매우 중요하다. 본 논문에서는 이러한 고립공간 작업자의 안전을 모니터링하기 위한 헬멧에 부착할 수 있는 IoT 시스템을 위한 알고리즘을 제안한다. 이는 장치가 작업 중에 긴급 상황인지 신속하게 판단할 수 있다. 스마트폰은 누구나 들고 다니기 때문에 사용자 환경은 스마트폰을 이용하여 적용되었다. 작업자들이 착용할 용도이기 때문에 PPG 센서는 불편하지 않도록 귀에 부착한다. PPG 센서를 단독으로 사용하여 스트레스 정도를 파악한다. 3축 가속도 센서는 헬멧에 부착되고 추락을 감지하는데 사용된다. 우리는 여러 센서와 블루투스 통신을 이용하여 발전된 센서 시스템을 만든다. 또한, 우리는 3축 가속도 샘플을 분석하고 정규화하는 알고리즘을 JAVA에서 구현하였다. 스마트 폰을 사용하는 이점은 신호 처리를 위해 별도의 마이크로프로세서(mcu)가 필요하지 않으며 내부 통신 시스템을 통해 제어 센터에 정보를 전송할 수 있다는 것이다.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.44 no.10
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• pp.911-920
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• 2016

For the pitch and yaw axis attitude control of launch vehicle, thrust vector control which changes the direction of thrust during the engine combustion is commonly used. Hydraulic actuation system has been used generally as a drive system for the thrust vector control of launch vehicles with the advantage of power-to-weight ratio. Nowadays, due to the developments of highly efficient electric motor and motor control techniques, it has done a lot of research to adopt electro-mechanical actuator for thrust vector control of small-sized launch vehicles. This paper describes system design and test results of the prototype of direct drive electro-mechanical actuation system which is being developed for the thrust vector control of $3^{rd}$ stage engine of KSVL-II.

• Journal of the Institute of Convergence Signal Processing
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• v.12 no.3
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• pp.222-227
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• 2011

2-axis tracking solar PV system applying a fixed-type unit than in the same area as the panel's power output to more than 140% can be obtained that have been identified. However, this approach compared with fixed or 1-axis control system and control the complexity of trekking equipment power the cursor comes to a relatively small output PV unit is called. In this paper, a small PV power units as a way to improve the economics of the small output of multiple PV units in the central control unit in enclosed places an intermittent manner by a remote control for each unit of the trek at the same time to simplify the control mechanism to reduce power that will be introduced. also the construction of large-scale PV development plans in difficult environments can be utilized in a manner appropriate to introduce.

• Plant Journal
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• v.14 no.3
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• pp.29-34
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• 2018

In this study, the output and thermal efficiency of Taean Integrated Gasification Combined Cycle Plant were calculated by using the manufacturer's basic design data and the performance correction factor for each atmospheric temperature, and the actual performance was measured at summer and winter representative points. The results were compared with the calculated values to verify their validity. The thermal efficiency is the highest at around $15^{\circ}C$ and lower at lower temperature and higher temperature. This is similar to that of natural gas Combined Cycle Power Plant, but the thermal efficiency has drastically decreased due to the increase of power consumption of the air separation unit at relatively high temperature. The output is highest in the range of 5 to $15^{\circ}C$, and is kept almost constant at below $5^{\circ}C$ and declines above $15^{\circ}C$. The reason why the output does not increase at low temperatures is that the torque limit of the shaft is activated by the increase of the flow rate due to the nitrogen injection of the gas turbine combustor. In order to improve the performance in the future, efforts should be made to improve the power generation output and to reduce the power consumption of the air separation unit in summer.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.23 no.12
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• pp.191-200
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• 2009

This paper, which consists of two parts, dealt with the parameter tuning of the power system stabilizer for a 612[MVA] thermal power plant in KEPCO system and its validation in field test. In Part 1 of the paper, the selection of parameters such as lead-lag time constants for phase compensation, system gain was optimized by using linear & eigenvalue analyses and they were verified through the time-domain transient stability analysis. In part 2, the performance of PSS was finally verified by the generator's on-line field test. Through the comparisons of simulation results and measured data before and after tuning of the PSS, the models of generator and its controllers including AVR, Governor and PSS used in the simulation are validated and confirmed.

• Nuclear Engineering and Technology
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• v.27 no.4
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• pp.555-561
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• 1995

This paper examines the applicability of the modified Borresen's coarse-mesh method(MBSN) to the core power distribution monitoring program development for the Yonggwang nuclear power plant unit 3(YGN 3) which uses fixed incore detectors for monitoring core power distribution. In so doing the modified Borresen's coarse-mesh equations are solved with core internal boundary conditions provided by the fixed incore detectors and three-dimensional core power distributions are com puted for the first-cycle core of the YGN 3 PWR. The results are compared with predictions of the COLSS(Core Operating Limit Supervisory System) which is the axial power shape monitoring program of the YGN 3. It is shown that the modified Borresen's method can reproduce the core axial power shape more closely than the COLSS. Because of other advantages in computing speed and predictive capability, n conclude that the proposed MBSN has a promising practical application for core power distribution monitoring program development.

• Journal of the Korean Institute of Educational Facilities
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• v.20 no.2
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• pp.25-32
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• 2013

The purpose of this study is to analyze the state-of-the-art solar energy system design cases among LEED(Leadership in Energy and Environmental Design) certified school projects and to explore the feasibilities for their applications in domestic school design. Investigating the sold wattages in some kinds of buildings, the wattages per an educational facility is the second-largest after that per an industrial facility. That shows that our attention should be actively directed to the utilization of New and Renewable Energy in school facilities. Therefore photovoltaics systems, lighting systems and solarthermal facilities of solar energy systems were analyzed in the LEED cases. Findings demonstrate that applications of solar energy systems in K-12 educational facilities have been executed more than those in higher educational facilities. However, K-12 educational facilities and higher educational facilities by private funds are not categorized as Green Buildings by Support for Making Green Buildings Act. That fact is needed to be amended. Besides that, design developments are needed for building integrated photovoltaics systems and solarthermal facilities in domestic educational facilities.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.23 no.8
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• pp.543-548
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• 2011

New concept of wind energy conversion system is proposed to increase the energy density at a given working space. The quality of wind for wind power generation is depend on its direction and speed. However, the quality is not good on land because wind direction is changeable all the time and the speed as well. The most popularly operated wind turbine system is an axial-flow free turbine. But its conversion efficiency is less than 30% and even less than 20% considering the operating time. In this research, a cross-flow type wind turbine system is proposed with a convergent-divergent duct system to accelerate the low speed wind at the inlet of the wind turbine. Inlet guide vane is also introduced to the wind turbine system to have continuous power generation under the change of wind direction. In here, the availability of wind energy generation is evaluated with the change of the size of the inlet guide vane and the optimum geometry of the turbine impeller blade was found for the innovative wind power generation system.

• Journal of Energy Engineering
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• v.2 no.2
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• pp.200-207
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• 1993

A methanol reformer was designed and fabricated using a CuO-ZnO low temperature shift catalyst, and its operation characteristics have been studied for the phosphoric acid fuel cell (PAFC) power generation system. The type of reactor was annular Methanol was consumed both for heating and for reforming fuel. Contents of carbon monoxide produced from the reformer increased as the reaction temperatures increased, but decreased as the mole ratios of water to methanol(H$_2$O/CH$_3$OH) increased. At steady state operating conditional, temperature profile of the catalytic reactor of the reformer was well coincide with the model equation, and it took 50 minutes from start to the rated condition of the reformer. When the system was operated at 4/4 and 1/4 of load, thermal efficiencies of the system were 72.3% and 77%, respectively. When the PAFC system was operated with reformed gas in the range of 62 V-37.6 V and 0-147 A, the trend of I-V curve showed a typical fuel tell characteristic. At steady state condition, the flow rates of reforming and combustion methanol were 88.1 mol/h and 50.1 mol/h, respectively.