• 대한설비공학회:학술대회논문집
• /
• 대한설비공학회 2009년도 하계학술발표대회 논문집
• /
• pp.623-628
• /
• 2009

Desiccant based air conditioning system offers a promising alternative to conventional one using vapour compression refrigeration for energy saving and greenhouse gas reduction. It is a heat driven cycle which has high potential for the use of low grade heat source such as the waste heat from the cogeneration plant or the solar thermal energy. In this study, the cooling performance of a desiccant cooling system incorporating a regenerative evaporative cooler was characterized in various operation conditions through numerical simulation. The cooling capacity and COP were evaluated at various outdoor conditions, regeneration temperatures, and supply flow rates. Based on the performance characteristics, the optimal control scheme was discussed to minimize the cooling cost at part load condition.

• 유체기계공업학회:학술대회논문집
• /
• 유체기계공업학회 2004년도 유체기계 연구개발 발표회 논문집
• /
• pp.680-686
• /
• 2004

Recently, the application of variable geometry turbocharger (VGT) to the high speed direct injection (HSDI) diesel engine has gained more and more interest in automotive industry. A steady state experimental investigation has been undertaken on a 1.5L HSDI diesel engine to verify the benefits of VGT comparing to the standard engine having a waste gate turbocharger (WGT). Specifically, part load performances (e.g., fuel economy and emission) have been investigated under various vane angles of the VGT. The results show that the real exhaust gas recirculation (EGR) rate as well as the pumping loss is very important to improve break specific fuel consumption (BSFC). It was previously known that the pumping loss only is a main parameter. In addition, the trade-off relationship between BSFC and NOx according to boost pressure, and the decreasing tendency of NOx with increasing real EGR rate have been verified. 1-D numerical analysis also has been performed, and the numerical results are in good agreement with experimental results.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2005년도 제36회 하계학술대회 논문집 B
• /
• pp.1368-1370
• /
• 2005

Satellite is operated only with internal battery when separated from rocket. Internal battery is charged only from SAR(solar Array Regulator), solar cell. So battery will be exhausted and purpose of satellite will be failed if load module is out of order or short. This paper proposed real time current limiter which operated by telemetry of outer processor. This current limiter operates by control signal simultaneously cuts off over current by self over current sensing circuit. So it can reduce waste of battery energy and over load of outer processor.

• 자원리싸이클링
• /
• 제18권3호
• /
• pp.11-19
• /
• 2009

최근 지구환경의 문제가 사회적 이슈로 부각됨에 따라 자원절약 및 자원의 유효이용이라는 측면에서 일상생활에서부터 각종 산업분야에 이르기까지 재활용과 자원절약에 관한 관심이 날로 심화되고 있는 가운데 지구 온난화 방지, 자연환경파괴의 방지, 폐기물에 의한 환경오염 방지 등 지구환경보전 측면에서 콘크리트용 골재 자원의 고갈, 시멘트 소성에너지, $CO_2$ 저감 등은 해결이 불가피한 문제로서의 당면한 과제이다. 이에 따라 건설 산업의 분야에 있어서도 건축물의 내부에 축적되어 있는 막대한 양의 자원을 유효하게 활용하고 내구수명이 길게 설계된 장수명화 건축물을 안전하고 쾌적하게 유지 관리함으로써 불필요한 건설행위를 억제하여 지구자원 및 에너지를 절감하는 창조적인 사고가 필요하다고 할 수 있다. 본고에서는 건설폐기물 발생 억제 및 유한한 지구자원의 유효이용과 재활용을 활성화시킴으로서 지구환경부하 저감을 위한 건축생산 및 건축물의 성능설계 측면에서 건축적 요구와 지구환경을 고려한 건축물의 장수명화를 위한 방법 및 건설폐기물의 유효이용기술에 대해 소개하였다.

• 공업화학
• /
• 제17권1호
• /
• pp.58-61
• /
• 2006

본 연구는 폐플라스틱용기 미디어 산화공법을 이용하여 유체 및 산소전달 효율 향상을 위한 개조 방법과 미생물 부착특성을 향상시키는 방법을 통하여 오수고도처리 함을 목적으로 하고 있다. 또한 실험실 규모의 실험에서 최적의 담체 층진율과 충진 방법을 도출함으로써, 실 규모 설비를 위한 최적 설계 인자와 운전인자를 확보하고, 오수의 고도처리를 위한 다양한 운전조건을 제공하여 폐플라스틱 용기를 미생물 담체로 사용할 경우 생물학적 반응에 의해서 분해 될 때 소비되는 산소량과 오수중에 현탁되어 있는 유, 무기성 부유물과 질소 제거가 이루어지는 메카니즘을 규명하고 오수 처리 효율 향상을 위한 운전인자 도출을 목표로 한다.

• 한국전산구조공학회논문집
• /
• 제25권1호
• /
• pp.57-64
• /
• 2012

방사성폐기물의 처리과정에서 발생한 설계하중 이상의 지진은 방사성 물질을 외부로 노출시킬 수 있으므로 방사성폐기물 처분장은 설계시 지진에 대하여 충분한 여유도를 가지도록 설계되어야 한다. 본 연구에서는 방폐장의 지상구조물에 대한 지진성능을 평가하기 위하여 지진 취약도 분석을 수행하였다. 지진 취약도 평가에 의하면, 해석모델로 선정된 인수저장 시설과 방사성폐기물 건물은 장방형의 구조물로써 구조물의 축에 따라 지진 성능이 약 23%~43% 다르게 나타났다. 최소 손상수준을 기준으로 할 경우 인수저장시설과 방사성폐기물 건물의 HCLPF성능은 각각 0.52g와 0.93g로 나타났으며, 방사성폐기물 건물은 원전의 격납건물과 유사한 지진성능을 보였다.

• 한국지반환경공학회 논문집
• /
• 제6권4호
• /
• pp.37-46
• /
• 2005

폐타이어는 높은 인장저항력으로 인하여 지반보강에 사용될 수 있을 뿐 아니라 재활용시 대량처리에도 효과적이다. 폐타이어를 지반보강재로 사용하기 위하여 타이어 트레드만을 이용한 트레드매트를 제작하였다. 현장에서 화강풍화토지반을 조성하여 트레드매트의 보강효과를 알아보기 위하여 트레드매트와 상업용 지오그리드 각각에 대한 평판재하시험을 수행하였다. 그리고 지반보강재 인접 지반에서의 응력과 변형을 알아보기 위해 수치해석을 수행하였다. 트레드매트는 상업용지오그리드 못지 않은 지반보강효과를 나타내었다. 유한요소해석결과 지반보강재 바로 밑에서 응력의 현저한 감소를 나타내었으며 보강재로 인한 응력분포를 확인할 수 있었다. 최종적으로 폐타이어의 대량처리를 위한 수단으로 지반보강을 위한 트레드매트의 사용이 제안되었다.

• 환경위생공학
• /
• 제5권1호
• /
• pp.83-92
• /
• 1990

Adapting two step aeration system to a waste water treatment of W-paper manufactory as Full-Scale Plants, we drew a following conclusion from its practical working. 1. Because BOD removal efficiency was 20% in A-Stage, 90% in B-Stage and total removal efficiency was 97%. It worked treatment plant well and was suitable for effluent water standard as well. Because COD removal efficiency was 42% in A-stage, 71% in B-stage and the total removal efficiency was 94% COD control was possible in effluent water quality. 2. Treatment efficiency according to a load capacity was average 20% in 1.401 BOD kg/m3/d load of A-Stage and average 90% in 0.273 BOD kg/$\textrm {m}^3$ / d load of B-Stage. 3. Treatment efficiency according to a ratio of F/M was 2.657--5.024 kg BOD/kg MLSS/d in A-Stage and BOD removal efficiency was 16-261 in the same stage. The ratio of F/M was 0.068-0.094 kg BOD /kg MLSS/d and BOD removal efficiency ratio was 85-94%. Therefore treatment efficiency could be kept stably and volume of aeration tank could be reduced wholly. 4. Treatment efficiency according to MLSS appeared BOD 20%. COD 42%, in A-Stage and removal efficiency appeared BOD 90%, COD 71% in B-Stage. They were suitable for plan condition. 5. Because of working of complemented treatment plant by AB-Process. 20,000,000 Won a month was saved than the ordinary working cost. Therefore, it was assumed that invested cost could be recollected in 19 months or so consequently.

• Geomechanics and Engineering
• /
• 제3권3호
• /
• pp.219-231
• /
• 2011

Waste fills resulting from coal mining should consist of large, free-draining sedimentary rocks fragments. The successful performance of these fills is related to the strength and durability of the individual rock fragments. When fills are made of shale fragments, some fragments will be durable and some will degrade into soil particles resulting from slaking and inter-particle point loads. The degraded material fills the voids between the intact fragments, and results in settlement. A laboratory program with point load and slake durability tests as well as thin section examination of sixty-eight shale samples from the Appalachian region of the United States revealed that pore micro-geometry has a major influence on degradation. Under saturated and unsaturated conditions, the shales absorb water, and the air in their pores is compressed, breaking the shales. This breakage was more pronounced in shales with smooth pore boundaries and having a diameter equal to or smaller than 0.060 mm. If the pore walls were rough, the air-pressure breaking mechanism was not effective. However, pore roughness (measured by the fractal dimension) had a detrimental effect on point load resistance. This study indicated that the optimum shales to resist both slaking as well as point loads are those that have pores with a fractal dimension equal to 1.425 and a diameter equal to or smaller than 0.06 mm.

• 설비공학논문집
• /
• 제27권5호
• /
• pp.233-240
• /
• 2015

This paper discusses compressors operating number control strategy using cooperative logic to cope with variable partial load for high efficiency of a centrifugal water chiller. The cooperative logic is composed of a speed-up and speed-down controller, enabling smooth operation of compressors and equivalent distribution of thermal load in each compressor. This centrifugal water chiller design can be operated with high efficiency without incurring excessive energy waste and large transient phenomena at partial load states. Simulations in MATLAB and experiments in a real chiller system were conducted and verified the high efficiency control of a centrifugal water chiller achieved by the suggested strategy.