• 한국전산유체공학회지
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• 제6권1호
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• pp.14-20
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• 2001

The CFD analysis of the three-dimensional turbulent flow in the impeller and diffuser of an axial flow pump was performed. Not only the design point but also the off-design points were computed. The results were compared with available experimental data in terms of head generated. At the design point, the analysis accurately predicted the experimental head value. In the range of the higher flow rates, the results were also in very good agreement with the experimental data, not only in absolute value but also in term of slope. Although experimental data to be compared were not available in the range of the lower flow rates, the results well described the S-shape performance curve of the axial pump characteristic.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 제36회 하계학술대회 논문집 B
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• pp.1144-1146
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• 2005

This paper presents the optimal design reducing the rotor inertia in order to improve the driving characteristic of BLDCM for robots. The parallel Genetic Algorithm is performed to rotor inertia minimization in optimal design. Also, velocity profile with finite jerk method is introduced to reduce vibration of BLDCM. As a result, a torque characteristic is same although rotor inertia is reduced 2/3 compared with prototype model. And, maximum vibration value is reduced by 63.4[%1 according to apply finite jerk.

• Tribology and Lubricants
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• 제23권3호
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• pp.109-116
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• 2007

A scroll compressor is on the increase in the use for the cooling and ambition machinery because of the advantages about high efficiency, low vibration and low noise. The design of thrust bearing for scroll compressor has depended on the experience. The lubrication considering the squeeze flow was applied for high side shell and low side shell of scroll thrust bearing. This work was based on governing fluid lubrication equation at the general coordinate. It shows the behavior for an orbiting scroll with direct numerical analysis using FDM. This study obtained the theoretical design value by finding load capacity and tilting angle of an orbiting scroll for thrust bearing in a scroll compressor. Especially this work performed the analysis about the design parameter. The program was written using Visual C++ to enhance user to change the design parameter easily. In particular the result value and the pressure profile were displayed as windows in every step for user to understand without difficulty.

• International Journal of Air-Conditioning and Refrigeration
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• 제12권4호
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• pp.184-191
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• 2004

In order to improve the performance of a 2 room heat pump with a constant speed compressor, the optimum refrigeration circuit of the heat pump with different cooling and heating capacities is developed by applying capillary tubes. The refrigeration circuit is composed of four parts; a heating circuit, a cooling circuit, a by-pass circuit and a balance circuit. The performance of the 2 room heat pump are investigated from a rating experiment and a reliability experiment, using the calorimeter. Results of the rating experiment show that the capacity of heat pump is about $93\%$ of the design value. In particular, the capacity of the cooling single operation is about $13\%$ higher than the design value, and the capacity of the heating multi operation is about $5\%$ higher than the design value. From the reliability experi-ment, it is found that the lowest driving voltage of the compressor is about $75\%$ of the rating voltage. Also the compressor is reoperated normally under the flood back and the over load.

• 한국암반공학회:학술대회논문집
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• 한국암반공학회 2000년도 암반공학문제의 수치해석(Numerical Analysis in Rock Engineering Problems)
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• pp.223-228
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• 2000

본 연구에서는 발파 설계를 쉽게 하기 위하여 RBD(Rock Blasting Design)프로그램을 개발하였다 이 프로그램은 시험 발파 설계, 벤치 발파 설계, 그리고 발파 진동 해석의 기능을 가지며, 지질 특성 값과 발파 상수를 데이터베이스로 제공하고, 여러 상수 값을 재 입력함으로써 보다 빠르고 간편하게 설계할 수 있고 한번 입력한 상수 값을 사용자가 재사용 할 수 있도록 하였다.

• 정보저장시스템학회논문집
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• 제8권2호
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• pp.39-43
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• 2012

In spite of many advantages, the practical application of the thin film solar cell is restricted due to its low efficiency compared with the bulk type solar cells. This study intends to adopt the surface plasmon effect using nano particles to solve the low efficiency problem in thin film solar cells. By inserting Ag nano-particles in the absorbing layer of a thin film solar cell, the poynting vector value of the absorbing layer is increased due to the strong energy field. Increasing the value may give thin film solar cells chance to absorb more energy from the incident beam so that the efficiency of the thin film solar cell can be improved. In this work, we have designed the optimal shape of Ag nano-particle in the absorbing laser of a basic type thin film solar cell using the finite element analysis commercial package COMSOL. Design parameters are set to the particle diameter and the distance between each Ag nano-particle and by changing those parameters using the full factorial design variable set-up, we can determine optimal design of Ag nano-particles for maximizing the poynting vector value in the absorbing layer.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 1997년도 추계학술대회논문집; 한국과학기술회관; 6 Nov. 1997
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• pp.132-137
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• 1997

In this study, the effect of load torque on the synchronous whirling of a rotor system has been studied analytically. Results show that the critical value of load torque to damping exists above which synchronous response decreases with increasing load torque. It has been also shown that the synchronous whirling amplitudes are more sensitive to the value of eccentricity and the ratio of disk radius to shaft length of the rotor system than other design parameters for a fixed value of load torque.

• Journal of Electrical Engineering and Technology
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• 제10권1호
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• pp.30-40
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• 2015

For a shunt power quality controller (SPQC) the DC side voltage value which is closely related to the compensation performance is a significant parameter. Buy so far, very little discussion has been conducted on this in a quantitative manner by previous publications. In this paper, a method to design the DC side voltage of SPQC is presented according to the compensation performance in the single-phase system and the three-phase system respectively. First, for the reactive current and the harmonic current compensation, a required minimal value of the DC side voltage with a zero total harmonic distortion (THD) of the source current and a unit power factor is obtained for a typical load, through the equivalent circuit analysis and the Fourier Transform analytical expressions. Second, when the DC side voltage of SPQC is lower than the above-obtained minimal value, the quantitative relationship between the DC side voltage and the THD after compensation is also elaborated using the curve diagram. Hardware experimental results verify the design method.

• 한국건설관리학회논문집
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• 제10권1호
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• pp.114-125
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• 2009

본 연구에서는 확률적 LCC 및 확률적 성능평가를 고려한 설계 VA분석 방법을 제안하였으며, 신뢰성 해석의 개념을 도입하여 신뢰도를 확보한 의사결정을 지원하고자 하였다. 상기와 같은 목적과 방법에 따라 진행된 본 연구의 결과를 요약하면 다음과 같다: 1) 기능정의가 완료된 이후 도출된 대안들의 대안평가시 신뢰성 있는 분석을 위하여 개선된 설계VA 절차 와 가치상태함수를 정식화하였으며, 가치평가절차에서의 일관성 및 효율성을 확보하기 위하여 평가지표방안을 제시하였다. 2) 교량의 LCC분석을 위한 DB를 수집 및 분석하였다. 자료의 수집범위는 기존에 수행된 교량의 LCC분석 연구 문헌을 기초로 하여 분석하였으며, 분석결과에 대한 신뢰도 확보 및 수집된 자료의 불확실성 처리를 위해 MCS 기법을 적용하였다. 3) 대안별 성능평가를 위한 가중치 및 평가등급과 LCC 분석을 위한 LCC 분석모델, 분석기간, 할인율, 사용자비용, 안전점검 및 안전진단비용에 대한 조건을 제시하였다. 끝으로, 사례대상인 "OO대교 및 연결도로 건설공사 실시설계" 프로젝트에 대한 VA수행 사례를 중심으로 타당성을 검토하고 결론을 도출하였다.

• Architectural research
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• 제15권4호
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• pp.201-206
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• 2013

Special attention is required for the design of windows due to their high thermal vulnerability. This paper examines the problems that might arise in the application of the u-value, by reflecting the changes in the u-value of the window, depending on the window-to-wall ratio obtained in an energy demand analysis. Research indicates that the u-value of a window increases with an increase in the difference between the u-values of the frames and the glass. Relative to the changes in the u-value of the windows, the energy demand varied from 1.3% to 9.3%. Windows with a g-value of 0.3 or 0.5 displayed a higher energy demand than windows with a g-value of 0.7. Therefore, when the difference between the performance of the glass and the frame is significant, especially when the g-value is small, a modified heat transmission coefficient should be applied to the window size during the evaluation of the building energy demand.