• 한국산학기술학회논문지
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• 제1권2호
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• pp.9-14
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• 2000

건물의 에너지 효율과 절약을 위해 최근 주목을 많이 받고 있는 가변 풍량 유닛(VAV)에 대해 실제적인 적용을 위한 적분기를 가진 상태 궤환 제어기를 연구한다. 디지털 제어기에 적합하도록 제어기를 개발하게 되며, 디지털 제어기는 결과적으로 대상으로 하는 실내 공간의 온도와 급기 유량으로부터 VAV 유닛 댐퍼의 개도를 조절한다. 설정 온도의 변화와 외부 온도의 변화등의 조건에 대해 모의 실험이 수행되었으며, 단순화된 대상 실내 공간과 댐퍼 구동기의 모델링이 고려되어 제어기의 이득 파라미터와 시스템의 동특성과의 관계를 고찰한다.

• Nuclear Engineering and Technology
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• 제21권4호
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• pp.321-331
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• 1989

방사성 폐기물 소각기술 개발 자립의 일환으로 한국에너지연구소에서는 실험용 방사성폐기물 소각공정을 설치하여 운전중에 있다. 이 공정은 소각경험의 습득 및 소각 특성 시험, 여과기의 성능시험 등을 위하여 설치되었다. 종이와 폴리에틸렌 모의폐기물을 소각하여 공정의 경제성과 운전성을 나타내는 감용비과 제염계수를 결정하였다. 제염계수로부터 소각설비의 허용 비방사능치를 얻어내고 설비의 감용비를 산출하는 방법을 기술하였다. 실험용 소각공정에서의 가연성 폐기물에 함유된 핵종에 대한 인수기준치를 상기방법을 이용하여 제시하여 보았다.

• 정보처리학회논문지A
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• 제10A권5호
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• pp.425-432
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• 2003

이 논문에서는 모바일을 기반으로 하는 사진 트리 영상 랜더링을 통하여 효율적인 PDA 용 전자의 무기록(EMR ; Electronic Medical Record) 챠트를 제안하였다. 볼륨 렌더링을 위하여 최종 영상 공간 대신에 중간 영상 공간 공간 알고리즘을 사용하였고, 점 대 점 매핑으로 발생하는 Hole의 문제점을 해결하였다. 델타 트리 기반의 quad 트리를 사용함으로 볼륨 표현에 효과적이었고, 압축 효과가 높았다. 볼륨 렌더링을 사용하여 렌더링의 시간을 줄일 수 있었고, 영상기반 렌더링(image-based rendering) 을 이용한 PDA 를 사용하여 질적 향상과 효율화를 얻게 되었다.

• 대한기계학회논문집B
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• 제29권2호
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• pp.180-188
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• 2005

It is well known that a lean burn engine caused by stratified mixture formation has many kinds of advantages to combustion characteristics, such as higher thermal efficiency and lower CO, NOx levels than conventional homogeneous mixture combustion. Although this combustion can achieve low fuel consumption technology, it produces much unburned hydrocarbon and soot because of heterogeneous equivalence ratio in the combustion chamber. Therefore, the stratified mixture formation technology is very important to obtain the stable lean combustion. In this paper, fundamental studies for stratified combustion were carried out using a constant volume combustion chamber. The local effect of mixture formation according to control air-fuel distribution in the chamber was examined experimentally. In addition, the effect of turbulence on stratified charge combustion process was observed by schlieren photography. From this study, we found that the flame propagation speed increase with swirl flow and the swirl promotes the formation of fuel and air mixture.

• 전자공학회논문지D
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• 제34D권4호
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• pp.1-7
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• 1997

십자형 및 변형 십자형의 2차원 터널 내에서 전파 전파 문제를 FVTD(finite volume time domain)법을 적용하여 시간영역에서 해석하였다. FVTD법은 임의의 미소 다면체 셀(cell)에 대하여 맥스웰 방정식(Maxwell's equation)을 체적 적분한 것에 이산화하여 나타낸 차분 방정식이다. 이 방식의 장점은 불균질 매질을 포함하는 임의 형태의 경계치 문제를 쉽게 계산할 수 있는데 있다. 본 논문에서는 FVTD법을 이용하여 십자형 터널에 대해 전자파의 전파 현상을 수치 계산을 하고, 유효성을 검증하기 위해 실험치와 비교하였다. 수치 계산의 종단에 있는 흡수 경계 조건은 손실 매질에 있느 PML(Perfect Matched Layer)흡수 경계 조건을 적용했다.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2008년도 춘계학술대회논문집
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• pp.61-64
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• 2008

The present study of these experiments are close examination of spray characteristics that are continuous liquid jet and modulated pressure pulse liquid jet. The experiments were conducted using water, over a range of cross-flow velocities from 42${\sim}$136 m/s, with injection frequencies of 35.7${\sim}$166.2 Hz. Between continuous cross-flow jet and pressure pulsed cross-flow jet for characteristics of penetration, breakup point, spray angle and macro spray shape are investigated experimentally. In cross-flow field, main parameter of liquid jet for breakup was cross-flow stream rather than pressure pulse frequency. As oscillation of the periodic pressure that could make liquid jet moved up and down, the mixing efficiency was increased. Also, a bulk of liquid jet puff was detected at upper field of liquid surface. So, this phenomenon has a good advantage of mixing spray from concentration of center area to outer area. Because of pressure pulsation frequency, an inclination of SMD for the structured layer was evanescent. Cross-sectional characteristics of SMD at downstream area were non-structured distributions. Then cross-sectional characteristics of SMD size were about same tendency over a range that is effect of spray mixing. The tendency of volume flux value for various frequency of pressure pulse was same distribution. And volume flux was decreased when the frequency of pressure pulse increase.

• 대한기계학회논문집B
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• 제24권12호
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• pp.1652-1661
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• 2000

A visualization study using the schlieren method is adopted in an optically-accessible, cylindrical constant volume combustion chamber to identify the mechanism of ignition energy and ignition system interaction in spark ignited, lean gasoline-air mixture. In order to research the effects of ignition system on flame propagation, two kinds of ignition system are designed, and several kinds of spark plugs are tested and evaluated. To control the discharge energy, the dwell time is varied. The initial flame development is quantified in terms of 2-D images which provides information about the projected flame area and development velocity as a function of ignition system and discharge energy. The results show that high ignition energy and extended spark plug gap can shorten the combustion duration in lean mixtures. The material, diameter and configuration of electrodes the flame development by changing the transfer efficiency from electrical energy to chemical energy and discharge energy. However these factors do not affect of flame development as much a ignition energy or extended gap does.

• 한국분무공학회지
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• 제14권2호
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• pp.59-64
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• 2009

These experiments are close examination of spray characteristics that are continuous liquid jet and modulated liquid jet. The experiments were conducted using water, over a range of crossflow velocities from $42{\sim}l36\;m/s$, with modulation frequencies of $35.7{\sim}166.2\;Hz$. Between continuous crossflow jet and modulated cross-flow jet of penetration, breakup point, spray angle and macro spray shape are experimentally investigated with image analysis. In cross-flow field, main parameter of liquid jet for breakup was cross-flow stream rather than modulation effect. As oscillation of the periodic pressure that could make liquid jet moved up and down, the mixing efficiency was increased. Also, a bulk of liquid jet puff was detected at upper field of liquid surface. So, this phenomenon has a good advantage of mixing spray from concentration of center area to outer area. Because of modulation frequency, SMD inclination of the structured layer was evanescent. Cross-sectional characteristics of SMD at downstream area were non-structured distributions. Then cross-sectional characteristics of SMD size were about same tendency over a range that is effect of spray mixing. The tendency of volume flux value for various modulation frequency was same distribution. And volume flux was decreased when the modulation frequency increase.

• 대한교통학회지
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• 제24권4호
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• pp.103-113
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• 2006

화물운송시장의 분할은 운송시장의 효율화를 기하고 운송인이 물동량을 유치하기 위한 전략을 알기 위해 사용된다 화주 개개인의 성향을 파악하기 어려우므로 화주를 동질성을 갖는 몇 개의 군집으로 묶어 집단의 성향을 파악한다. 우리나라의 경우 표준산업분류의 배열순서에 따라 시장분할을 하여 왔다. 본 연구는 제조업체를 대상으로 새로운 운송시장 분할 가능성을 평가하였다. 연구의 결과 시장분할을 위한 적정 기준은 연간 입 출하량으로 우수한 분할능력을 보였다 또한 표준산업분류표의 배열순서에 따른 시장분할과 다른 결과를 도출하였다 본 연구는 물동량 발생 주체인 제조업체의 규모와 출하특성을 나타내는 자료를 이용하여 운송시장을 분할한 시도로서 의의가 있다.

• 한국자동차공학회논문집
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• 제23권4호
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• pp.428-435
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• 2015

This paper presents the experimental study of cabin thermal comfort using a cold storage heat exchanger in a vehicle air-conditioning system. Recent vehicle-applied ISG functions for fuel economy and emission, but when vehicles stop, compressors in the air-conditioning system stop, and the cabin temperature sharply increases, making passengers feel thermal discomfort. This study conducts thermal comfort evaluation in the vehicle, which is applied to a cold storage system for the climate control wind tunnel test and the vehicle fleet road test with various airflow volume rates and ambient temperatures blowing to the cold storage heat exchanger. The experimental results, in the cold storage system, air discharge temperature is $3.1-4.2^{\circ}C$ lower than current air-conditioning system when the compressor stops and provides cold air for at least 38 extra seconds. In addition, the blowing airflow volume to the cold storage heat exchanger with various ambient temperature was examined for the control logic of the cold storage system, and in the results, the airflow volume rate is dominant over the outside temperature. For this study, a cold storage system is economically useful to keep the cabin at a thermally comfortable level during the short period when the engine stops in ISG vehicles.