• 한국재료학회지
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• 제9권12호
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• pp.1216-1221
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• 1999

TMGa와 유전체 장벽방전에 기초한 질소함유 활성종을 이용하여 (0001) 사파이어 기판위에 GaN 박막을 저온에서 성장시켰다. III-V 질소화합물 반도체의 에피막 성장에 있어서 암모니아는 유기금속 화학증착법에서 지금까지 알려진 가장 보편적인 질소 공급원이며 충분한 질소공급을 위해 $1000^{\circ}C$ 이상의 고온 성장이 필수적이다. GaN 박막을 비교적 저온에서 성장시키기 위하여 질소 공급원으로 암모니아 대신 유전체 장벽방전을 이용하였다. 유전체 장벽방전은 전극사이에 유전체 장벽을 설치하여 arc를 조절하는 방전이며 수 기압의 높은 공정압력보다 훨씬 높으므로 기판표면까지 전달하는데도 이점이 있다. GaN 박막의 결정성과 표면형상은 성장온도, 완충층에 따라 변화하였으며, $700^{\circ}C$의 저온에서도 우수한 (0001) 배향성을 갖는 GaN 박막을 성장할 수 있었다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회B
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• pp.1948-1952
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• 2007

Heat transfer augmentation based on the process intensification concept in heat exchangers and thermal reactors has received much attention in recent years, mainly due to energy efficiency and environmental considerations. The concept consists of the development of novel apparatuses and techniques that, compared to those commonly used today, are expected to bring dramatic improvements in manufacturing and processing, substantially decreasing equipment size, energy consumption, and ultimately resulting in cheaper, sustainable technologies. The objective of this paper was to investigate the heat transfer characteristics of tubular thermal reactor using static mixing technology. Glycerin and water were used as the test fluids and water was used as the heating source. The results for heat transfer rate were strongly influenced by tube geometry and flow conditions.

• 제어로봇시스템학회논문지
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• 제7권1호
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• pp.1211-1217
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• 2001

This paper presnts a controller for the heat capacity of thermal storage systems using off-peak electricity which is composed of an identifier using neural networks and a storage time adjuster in order to store exactly the required thermal energy without loss. Since thermal storage systems have nonlinear characteristics and large time constant, even if we predict the heating load accurately, it is very difficult to store exactly the required thermal energy. Thus, in the neural network for the identifier, the adaptive learning rate for high learning speed and bit inputs based on state changes of thermal storage power source are used. Also a hardware for the controller using a microprocessor is developed. The performance of the proposed controller is shown by experiment.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2003년도 ICCAS
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• pp.1371-1376
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• 2003

In the thermal power plant, the main steam temperature is typically regulated by the fuel flow rate and the spray flow rate, and the reheater steam temperature is regulated by the gas recirculation flow rate. However, Strictly maintaining the steam temperature can be difficult due to heating value variation to the fuel source, time delay changes in the main steam temperature, the change of the dynamic characteristics in the reheater. Up to the present time, PID Controller has been used to operate this system. However, it is very difficult to achieve an optimal PID gain with no experience, since the gain of the PID controller has to be manually tuned by trial and error. This paper focuses on tuning of the 2-DOF PID Controller on the DCS for steam temperature control using immune based multiobjective approach. The stable range of a 2-DOF parameter for only this system could be found for the start-up procedure and this parameter could be used for the tuning problem. Therefore tuning technique of multiobjective based on immune network algorithms in this paper can be used effectively in tuning 2-DOF PID controllers.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2004년도 ICCAS
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• pp.885-890
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• 2004

Strictly maintaining the steam temperature can be difficult due to heating value variation to the fuel source, time delay changes in the main steam temperature, the change of the dynamic characteristics in the reheater. Up to the present time, PID Controller has been used to operate this system. However, it is very difficult to achieve an optimal PID gain with no experience, since the gain of the PID controller has to be manually tuned by trial and error. This paper focuses on tuning of the Controller with disturbance rejection for thermal power plant using immune based multiobjective approach. An ITSE(Integral of time weighted squared error) is used to decide performance of tuning results.

• 혜화의학회지
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• 제16권1호
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• pp.31-40
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• 2007

Hominis placenta have been studied as herbal acupuncture because of it's limitation of use. The properties of Hominis placenta are warm and supplement of Jeong-Hyeol, Jin-Ki and I thought that Hominis placenta have various effectiveness. So I considered Hominis placenta in Dong-Eui-Bo-Gam which is famous comprehensive korean traditional medical book. Hominis placenta was mentioned parts of Sin, Chung, Hwa, Heo-Ro, Bu-In and most of them are mentioned in Heo-Ro part. As a source book, Eui-Hak-Ib-Mun was used the most. Prescription used in various parts as mental disease, forgetfulness, tuberculosis, fever, various malnutrition disease, sterility, but it's basic principle action is all supplement of Heo-Ro. In management of Hominis placenta, most useing method is heating with steam and most of additional medicinal stuffs had action of supplying Eum, Yang, Ki, Hyeol in composition of prescription.

• 동력기계공학회지
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• 제9권2호
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• pp.99-105
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• 2005

LNG Vaporizers must be smaller, more efficient, and easier to operate and maintain. Recently, the vaporizers with greatly enhanced performance as compared to conventional type, have been developed to fulfill these requirements. The vaporizing characteristic of LNG vaporizer with air as heat source has fixed ice. These characteristic has efficient down and total plant cost and installing space can be increase. On that reasons must be optimize through tube and pipes analysis and experiments with enhanced type in this study. In this study performance to the workong characteristics for air heating type vaporizer for super low temperature liquefied gas.

• 전기학회논문지P
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• 제54권3호
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• pp.134-140
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• 2005

Most of the loads in industrial power distribution systems are usually balanced and connected to three power systems. However, in the user power distribution systems, partial loads are single & three phase and unbalanced, generating voltage unbalance by the impedance mismatching. Voltage unbalance has detrimental effects on three-phase induction motors, including over heating, line-current unbalance, derating, torque pulsation, low efficiency, etc. This paper presents a scheme on operation states of a three-phase induction motor under the unbalanced voltages with harmonics components. Three-phase voltages applied to the stator winding of the studied induction motor are controlled by respectively adjusting not only fundamental but also harmonics components. Harmonic components at the voltage unbalanced factor(VUF) of the three-phase source voltages can then be examined the different values of VUF on machine's operation characteristics.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1996년도 하계학술대회 논문집 A
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• pp.495-497
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• 1996

This paper proposes LCC type high frequency resonant inverter to be used as a source of induction heating device or ultrasonic device and considers of operating characteristic for it. The inverter is operated safely over wide range load, because it has both panel loaded capacitor and series loaded capacitor. Then, switching frequency of the inverter is controlled by feedback voltage and current in order to have constant output power even when load is varied.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2000년도 추계 학술대회논문집
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• pp.72-77
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• 2000

This paper presents the results of the application of a computational fluid dynamics algorithm for the simulation of plasma flows of arc-heated jet. The underlying physical model is based on the axisymmetric form of the conservation equations that are coupled with an arc model including Ohm heating, electromagnetic forces. The arc model given as a source term in fluid dynamic equations is determined by a solution of electric potential field governed by an elliptic partial differential equation. The governing equation of electric field is loosely coupled with fluid dynamic equations by an electric conductivity that is a function of state variables. However, the electric fields and flow fields cannot be solved In fully coupled manner, but should be solved iteratively due to the different characteristics of governing equations. With this solution approach, several applications of arc flow analysis will be presented including Arc Thruster and Circuit Breaker.