• Journal of the Korean Institute of Gas
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• v.4 no.4 s.12
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• pp.13-19
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• 2000

Researches on unused energy are being continued because of the limited fossil fuel and the destruction of environment. Therefore this study was performed as follows The collectable amount of exhausted heat for an air-conditioning was calculated by the subway thermal environment prediction program. And the electric power needed by conventional heat source equipments was compared with one by unused heat source equipments when the exhausted heat was used by heat pump in heating and hot water supplying.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.8B
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• pp.826-833
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• 2002

Generally, it is announced that RZ pattern gives a better transmission performance than NRZ pattern in ultra-high speed transmission above 10Gbps. In this paper, we propose a wavelength converter for RZ data which can controls XPM in SOA by locating polarization controllers within optical fiber loop mirror and demonstrate its performance through simulation and 10Gbps data experiment. The proposed structure needs only one polarization dependent SOA for implementation compared to previous XPM ones to make the cost down. And it provides non-inverted pattern outputs at two output ports respectively.

• Fire Science and Engineering
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• v.29 no.6
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• pp.119-128
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• 2015

A fire broke out in a working wood-burning stove and destroyed an idyllic house about two years after it was built. This study analyzed data provided through the court by the fire station, police station, fire insurance investigation agency, house construction company, and wood-burning stove maker Based on the fire pattern of low-temperature long-term ignition that remained in the studs, the fire was found to be caused by the conduction of heat in the fire box to the studs of the wall next to the wood-burning stove. A fire simulation showed that the low-temperature long-term ignition of the studs next to the wood-burning stove occurred because a hole was not made for ventilation in the chimney.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.7 no.1
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• pp.161-170
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• 1995

This study is concerned with the numerical analysis of performance on fin-tube heat exchanger under frosting condition. In this work, tube-by-tube method using LMED is employed. The present results are compared with O'Neal's experimental and numerical results. A standard evaporator model with 2rows-2columns is selected to investigate the effects of the various parameters such as fin pitch, air flow velocity, and humidity. The results show that frost thickness and the amount of frost per unit area decrease as fin-pitch becomes narrower. In the meantime, frost thickness and accumulation rate increase with higher inlet air humidity. It is shown that heat transfer rate increases during 30minutes and then it decreases. Heat transfer rate and the amount of frost increase with air velocity, however frost thickness does not increase over a certain velocity.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.21 no.5
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• pp.282-290
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• 2009

A ceramic monolith heat exchanger is studied to find the performance of heat transfer and pressure drop by numerical computation and $\xi$-NTU method. The numerical computation was performed throughout the domain including fluid region in exhaust gas-side rectangular ducts, ceramic core and fluid region in air-side rectangular duct with the air and exhaust in cross flow direction. In addition, the heat exchanger was also analyzed to estimate the performance by conventional $\xi$-NTU method with several Nusselt number correlations for flow in rectangular duct from literature. By comparisons of both performances by the numerical computation and the $\xi$-NTU method, the effectiveness by $\xi$-NTU method was closest to the result by numerical computation within a relative error of 2.14% when Stephan's Nusselt number correlation was adopted to the $\xi$-NTU method among the several correlations.

• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.5 no.1
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• pp.46-56
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• 1991

In this paper, the variable speed control of permanent magnet synchronous motor driven by a sinus¬oidal PWM inverter based on maximum torque sensitivity is presented. The developed torque or speed control is achieved by the field orientation technique. For the field orientation, the resolver is used as the rotor positioning sensor mounted on the motor shaft without pull-out of the synchonism at any speed. To show the validity of proposed control method, the simulation and experimental results are provided. The advantages of the proposed control method are to achieve the fast current and speed responses.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2001.10a
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• pp.359-362
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• 2001

Phase shifter has been used as a means of power-flow control and for transient stability improvement in AC transmission system. Until now, phase shifters have been based on an injection transformer. Conventional phase shifters with tap changers require regular maintenance and allow only step-like control of the phase an81e. This paper propose a three-phase phase shifter using PWM AC/AC converter, which can improve system response and control stability in the applications. This paper deals with the circuit topology, operating principle so that the features of the phase shifter will be shown through computer simulation, especially using PSIM software.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.23 no.2
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• pp.153-163
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• 2011

Energy efficiency and indoor air quality have become main issue to develop healthy and sustainable building in these days. As an effort to reduce the energy consumption in multi-residential building, many attempts as like passive design strategies and renewable energy as well as active control method are tried. However, underground parking lot in multi-residential building seldom adopt the sustainable strategies and only mechanical system is installed as usual. Moreover, the mechanical system installed in underground parking lot is rarely operated due to the electric demand for operation after completion. In this study, as an energy efficient measure, natural ventilation system using stack effect as a driving force for underground parking lot will be proposed and the performance of the suggested system will be analyzed by simulation method.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.6
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• pp.4253-4259
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• 2015

In this study, the effects of various control methods of outdoor air cooling control system on control characteristics and energy consumption in building are researched by simulation. The system analysis modelling is done by using TRNSYS program package, and the control performances with existing outdoor air cooling methods are compared with the control ones without outdoor air cooling. As a result, appropriate operating temperature conditions of outdoor air cooling system according to outdoor temperature changes are required, and the outdoor air/return air dry bulb temperature comparison control method among the control methods shows best responses in energy savings.

• Journal of the Korea Safety Management & Science
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• v.19 no.4
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• pp.115-123
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• 2017

Recently there is a growing interest in the airborne spread of virus. In particular, there is growing interest in secondary infection through the air in the hospital. The distribution of air-born virus depends on ventilation system installed in a hospital. In this study, simulations were carried out to predict the move of air-born virus by ventilation system at hospital. Simulation results showed that pressure distribution was -372.05Pa ~ -3.45 Pa at 1st floor incase of only used mechanical exhaust at bathroom, shower stall, storage, kitchen etc.. if ventilation switch from used mechanical exhaust to mechanical exhaust & mechanical supply. Simulation results showed that pressure distribution was -336.44Pa at stair hall < -0.2Pa at bathroom < mean 1.19Pa at other room. So simulation results showed that using all of the mechanical supply and mechanical exhaust was more effective then the mechanical exhaust for maintain the pressure distribution in hospital. It was also showed that when using the mechanical supply and mechanical exhaust more effectively prevention of air born virus diffusion.