• KIEAE Journal
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• 제4권4호
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• pp.19-26
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• 2004

The purpose of this study was to evaluate the thermal environment of present state and energy consumption and to verify the improvement of energy performance applying free cooling in 5ESS-2000 telecommunication equipment room. Analysis program is used the DOE-2.1E and commercial CFD code, Star-CD. The results of the simulation show that free cooling could reduce 42.1% of cooling energy, increase 48.5% of heating energy because introduced outdoor air must heating and humidification. Therefore free cooling could reduce yearly 34,609.9 kWh of heating and cooling energy and this is reaching to 21.6% of total energy.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• 제13권10호
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• pp.923-929
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• 2001

The objectives of this paper are to develop an advanced GAX cycle named HGAX (Hybrid Generator Absorber heat eXchange) cycle, and to study the effect of key pa-rameters on the cycle performance and the evaporating temperature. Two different HGAX cycles are developed-Type A (Performance improvement) and Type B (Low temperature applications). A compressor is placed between the evaporator and the absorber, and the evaporator pressure and the absorber pressure are controlled according to its application purpose. It was found that the COP could be improved by 24% compared with the conventional GAX cycle and the evaporating temperature as low as -8$0^{\circ}C$ could be obtained from the HGAX cycle.

• Proceedings of the SAREK Conference
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• 대한설비공학회 2008년도 하계학술발표대회 논문집
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• pp.328-333
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• 2008

In order to control indoor air quality and save energy, it is needed to install a suitable heat exchanger for heat recovery. A plastic heat exchanger have many advantages and can recover $50{\sim}80%$ of the temperature difference between supply and exhaust air. The purpose of this research is to evaluate the performance of plastic heat exchanger with different shapes. Pressure drop and heat transfer characteristics of plastic heat exchangers are investigated for various velocities.

• Proceedings of the KIEE Conference
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• 대한전기학회 1997년도 하계학술대회 논문집 A
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• pp.211-214
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• 1997

This paper describes the position accuracy performance improvement of hybrid type LPM. The harmonics are included in the thrust force component of LPM, those are generated from the the nonlinearity of intrinsic magnetic saturation characteristic and mechanical construction, and so on. In this paper, the performance improvable methode is proposed for the better thrust force by the corrected exciting current injection, and precise position control is achieved.

• Journal of Drive and Control
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• 제10권2호
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• pp.1-6
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• 2013

This study describes a method which can attenuate reaction force effectively for an air spring system composed of an air spring and auxiliary chamber. For the analysis, the nonlinear governing equation of the air spring system is derived. For a performance improvement of the system, change of the heat transfer effect and the mass flow rates is included in the analysis of the air spring system. The simulation study is presented to show the reaction force is changed by variations in heat transfer characteristics and the air spring system of isothermal process has the best performance. As a result, to improve attenuation characteristics of reaction force, a process in the air spring system should be maintained near isothermal process.

• Journal of the Korea Society for Simulation
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• 제12권2호
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• pp.45-53
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• 2003

This paper presents a retargetable compiled assembly simulation technique for fast ASIP(application specific instruction processor) simulation. Development of ASIP which satisfies design requirements in various fields of applications such as telecommunication, wireless network, etc. needs formal design methodology and high-performance relevant software environments such as compiler and simulator In this paper, we employ the architecture description language(ADL) named ${HiXR}^2$ to automatically synthesize an instruction-level compiled assembly simulator. A compiled simulation has benefit of time efficiency to interpretive one because it performs instruction fetching and decoding at compile time. Especially, in case of assembly simulation, instruction decoding is usually a time-consuming job(string operation), so the compiled simulation of assembly simulation is more efficient than that of binary simulation. Performance improvement of the compiled assembly simulation based on ${HiXR}^2$ is exemplified with an ARM9 architecture and a CalmRISC32 architecture. As a result, the compiled simulation is about 150 times faster than interpretive one.

• Journal of National Security and Military Science
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• 통권2호
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• pp.91-119
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• 2004

Development of science technology, computer network and software technology has not only changed various areas of the society, but also brought rapid change in the condition and the way of performing war. Historical lessons learned from the war in Iraq tells that military capabilities corresponding to the new paradigms of war needs to be assured in order to preserve national interest and take victory in future warfare. Thus, the performance in the latest war in Iraq, the estimated performance in future war and the performance of war in the Korean Peninsula has been put together and analyzed to indicate the direction our force should be built and the structure to be improved. Under all circumstances and threats the military must defend our nation and territory. When war breaks out the military must perform it's basic duty to end war by decisive operations. As the saying is "To preserve peace, prepare for war," continuous increase of military strength and improvement of military structure corresponding to the change of national security environment and weapon system is necessary.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• 제28권12호
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• pp.55-64
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• 2014

This paper presents a case study to investigate the monthly calculation method of ISO 13790 applied for a office building. The energy performance analysis according to improvement of insulation and air permeability of windows in K office buildings is investigated by means of building energy efficiency rating tool ($ECO_2-OD$). The K building energy system is tested experimently by the measurement of PMV(predicted mean vote) for the control of indoor thermal environment and heat transmission coefficient of windows and interior walls respectively, before and after the example K office building is remodeled passively. Therefore, Internet based energy assessment program of energy efficiency rating of office building can be applied as a program for the annual energy requirement and for evaluation of energy savings from the experimental and simulation results.

• Proceedings of the KIEE Conference
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• 대한전기학회 1999년도 하계학술대회 논문집 A
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• pp.179-181
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• 1999

Sensorless PMSM is much studied for the industrial applications and home appliances because a mechanical sensor reduce reliability and increases cost. Most of sensorless algorithm have poor performances in a low speed range. This paper investigates Performance improvement in a low speed range of PMSM. The proposed control scheme is based on the optimization of ratio between the command and dc-link voltages. The experiment is performed in this study. and the result shows the improved Performance in a low speed range.

• Proceedings of the KIEE Conference
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• 대한전기학회 2005년도 학술대회 논문집 전문대학교육위원
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• pp.176-179
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• 2005

In this paper, we propose the new method that separate the existing common VQ code book into two parts, one is the common VQ code book which is the half of existing common VQ code book, another is the personal speaker VQ code book which accommodate the personal speaker characteristic, variation to improve the performance of the text-dependent speaker verification system using discrete HMM. We apply the propose method m this paper to the text-dependent speaker verification system using discrete HMM and have the improvement performance of about 0.24% compared to existing method