• Korean Journal of Optics and Photonics
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• v.6 no.2
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• pp.115-121
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• 1995

본 논문에서는 일체형, Nd:YAG 고리 레이저에서 서로 반대방향으로 진행하는 두 모드의 비선형적인 상호작용에 의한 출력 불안정 현상을 조사하였다. 실험을 통하여 두 모드가 각각 단일 종모드로 발진함을 확인하였고, 레이저가 발진하는 임계치 부근의 낮은 펌핑수준을 유지하여 다중모드간의 경쟁이나 단방향 발진에 의한 출력 불안정이 아님을 확인하였다. 또한 잘 알려진 시스템 고유의 감쇄진동과 구별되는 현상임을 보였다. 두 모드간의 손실차가 클수록 이 출력의 변조주파수는 증가하고 변조폭이 줄어 들어 안정화 되며 단방향 발진이 일어난다.

• Proceedings of the KSME Conference
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• 2000.11b
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• pp.234-240
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• 2000

The Energy is the basis for almost all industrial activities and domestic needs. But recently there are increasing concerns internationally over environmental problems and consequent climate changes caused by the excessive use of fossil fuels. Furthermore the price of crude oil is increasing steadily with unstable supplies. In order to solve these national energy problems, the utilization of Ocean Energy is introduced as one of the best alternative technologies for the future. OTEC Power Plant has been installed at the West Inchon Power Plant Site. Temperature differences of $20{\sim}25^{\circ}C$ have been utilized for plant operations, where R22 is used as a working fluid. The system is composed of low pressure turbine, plate type heat exchanger, and pumps. In the present investigation the experimental results, such as gross power, net power and objective function, are analysed when temperature differences change from the reference design point.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.13 no.10
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• pp.1002-1008
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• 2001

The energy is the basis for almost all industrial activities and domestic needs. But recently there are increasing concerns internationally over environmental problems and consequent climate changes caused by the excessive use of fossil fuels. Furthermore the price of crude oil is increasing steadily with unstable supplies. In order to solve these national energy problems, the utilization of Ocean Energy is introduced as one of the best alterative technologies for the future. OTEC Power Plant has been installed at the West Inchon Power Plant Site. Temperature differences of$20~25^{\circ}C$ been utilized for plant operations, where R22 is used as a working fluid. The system is composed of low pressure turbine, plate type heat exchanger, and pumps. In the present investigation the experimental results, such as gross power, net power and objective function, are analysed when temperature differences change from the reference design point.

• Proceedings of the Korean Information Science Society Conference
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• 1998.10c
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• pp.506-508
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• 1998

본 논문에서는 경치 영상들에 대해 영상의 내용(색상, texture)에 기반하여 검색하는새로운 방법을 제안한다. 경치 영상들은 색상이 주 특징이며 결합되는 texture 특징들에 의해 영상 정보간의 유사성의 파악이 더 용이하다. 색상 특징은 HSV 색상 히스토그램에 의해 특징을 나타내며 영상의 전역적 색상 특징과 지역적 색상 특징으로 세분화되고 texture 특징은 2차원 Garbor filter에 의해 영상별 특징을 나타낸다. 시스템의 검색은 예제 영상에 의한 질의 방식으로 예제 영상을 주면 이와 유사한 영상들이 유사도가 높은 순위대로 출력하게 된다.

• Korean Journal of Optics and Photonics
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• v.8 no.3
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• pp.204-208
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• 1997

We analyze the intensity characteristics of the output beams of the ring laser, in which only one mode is generated in each direction, within the neoclassical model by using the Maxwell-Bloch equation. Considering the Nd:YAG crystal as a gain medium, we investigate the stability and the modulation of the output beam intensity as the pumping rate, the relaxation or the decay rate, and the frequency detuning vary, upon taking into account the effect of the beam in one beam in one direction onto the beam in the other direction. In particular, we examine the variation of the output beam intensity and the stability condition through a computer simulation.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.39 no.6
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• pp.513-518
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• 2015

Salinity gradient power (SGP) has attracted significant attention because of its high potential. In this study, we evaluate reverse electrodialysis (RED) with various compositions of available resources. The polarization curve (I-V characteristics) shows linear behavior, and therefore the power density curve has a parabolic shape. We measure the power density with varying compartment thicknesses and inlet flow rates. The gross power density increases with decreasing compartment thickness and increasing flow rate. The net power density, which is the gross power density minus the pumping power, has a maximum value at a compartment thickness of 0.2 mm and an inlet flow rate of 22.5 mL/min. The power density in RED is also evaluated with compositions of desalination brines, seawater, river water, wastewater, and brackish water. A maximum power density of $1.75W/m^2$ is obtained when brine discharged from forward osmosis (FO) and river water are used as the concentrated and the diluted solutions, respectively.

• Proceedings of the Optical Society of Korea Conference
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• 1996.09a
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• pp.13-13
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• 1996

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.35 no.6
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• pp.489-495
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• 2007

An experimental study was carried out in order to measure the pitch dynamic stability derivatives of a standard dynamics model in a low-speed wind tunnel. When a trigger signal is generated, the aircraft model starts oscillation with constant amplitudes and frequencies provided by DC electrical servomotor. The measured data are simultaneously recorded on a data recorder for 25 cycles of the model oscillation. The Phase shift needed to compute the dynamic stability derivatives is determined by calculating differences between the peak values of the input and output signals from the dynamic stability balance. Stabilator effects on the stability derivatives were also investigated with deflection angles. Although the driving apparatus and experimental equipments manufactured creatively for this study are different from other experiments, the variational trend of dynamic stability derivatives with the angle of attack is in a good accordance with the results of TPI, NAE, and FFA.

• Journal of Advanced Marine Engineering and Technology
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• v.38 no.1
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• pp.8-14
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• 2014

This research designed Waste Heat Recovery System(WHRS) generation system of 250kW whose working fluid is R-245fa and studied on cycle characteristics by superheater organization. It simulated two conditions; series connection and parallel connection between superheater and evaporator. In simulation of series connection of superheater and evaporator, output of 4.7% could be improved because of the increase of enthalpy by overheating of working fluid. When setting 250kW for target output, cycle flux could be reduced by 4.1%. When setting 250kW as a target output of cycle In parallel connection simulation of superheater and evaporator, cycle flux was reduced as flux of heat source fluid for superheater was increased. So, the maximum 7.9% of working fluid pump's electric power was reduced and there was no big change in cycle efficiency and net efficiency by flux ratio.

• Journal of KIISE:Computer Systems and Theory
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• v.27 no.9
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• pp.759-767
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• 2000

OPKFDD(Ordered Pseudo-Kronecker Functional Decision Diagram)는 각 노드에서 다양한 decomposition을 취할 수 있는 Ordered-DD(Decision Diagram)의 한 종류이다. OBDD(Ordered Binary Decision Diagram)에서 각 노드는 Shannon decomposition 만을 이용하는 반면, OPKFDD는 각 노드마다 Shannon, positive Davio, negative Davio decomposition 중의 하나를 사용하도록 하며 많은 경우 매우 적은 수의 노드로 함수를 표현할 수 있다. 그러나 각 노드마다 각기 다른 확장 방법을 선택할 수 있는 특징 때문에 입력 노드에 대한 확장 방밥과 입력 변수 순서의 결정에 의해서 OPKFDD의 크기가 좌우되며 이에 대한 최적의 해를 구하는 것은 매우 어려운 문제로 알려져 있다. 본 논문에서는 DD 크기를 기준을 노드 수로 하여 기존의 BDD(Binary Decision Diagram) 자료구조에서 OPKFDD를 효율적으로 유도해내는 방법을 제시하고 complex term을 이용하여 이를 최소화하는 알고리즘을 제시한다. 그리고 입력변수 순서 결정을 위하여 다출력함수의 경우 함수간의 포함관계를 고려한 그룹-sifting과 각 노드의 확장 방법을 제안하고 실험 결과를 제시한다.