• 한국화재소방학회:학술대회논문집
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• 한국화재소방학회 2008년도 춘계학술논문발표회 논문집
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• pp.131-134
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• 2008

본 연구에서는 가연성혼합물의 구성하는 각 순수성분의 연소열과 기상 조성을 이용하여 폭발한계를 예측하였다. 제시된 방법론에 의한 계산값은 적은 오차범위에서 문헌값과 일치하였다. 따라서 제시된 결과로부터 제시된 방법론이 다른 가연성혼합물의 폭굉한계 예측에 폭넓게 적용되기를 기대한다.

• 한국화재소방학회논문지
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• 제29권6호
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• pp.76-83
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• 2015

EPS 샌드위치 패널은 난연제의 첨가로 화재 시 발화를 늦춰주며 발열을 적게 발생시켜 연소의 확대를 막는다. 하지만 난연성능 기준에 미달하는 샌드위치 패널을 사용할 경우, 재산 및 인명 피해가 확대되는 사례가 발생할 수 있다. 마감재료의 난연성능은 육안으로는 확인이 어려워 간편하면서도 빠른 평가방법의 개발이 요구된다. 본 연구에서는 X-선 분석법(XRF, XRD)을 이용하여 EPS 샌드위치 패널의 화재안전평가 방법에 대해 분석하였다. X-선 분석법을 적용한 결과 화재시험을 통한 난연 성능에 따라 특정 성분이 검출되는 것을 확인하였다. X-선 형광분석(XRF)을 통해 알루미늄성분이 부적합제품에 비해 적합제품에 훨씬 많이 함유되어있는 것을 알 수 있었다. X-선 회절분석(XRD)을 통해 난연 EPS의 주된 결정성 물질로 확인된 깁사이트(gibbsite)는 적합제품과 부적합제품에 공통으로 함유되어 있었지만 결정성에 있어 차이가 나는 것을 확인하였다. 이러한 X-선 분석을 통한 원소분석과 결정분석으로 난연성능 평가 가능성을 확인하였다.

• 한국화재소방학회논문지
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• 제26권3호
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• pp.40-48
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• 2012

심하게 소손된 화재현장은 남아 있는 잔존물만으로 초기 화재의 유형을 판단하기 곤란할 때가 많다. 화재로 인해 사람이 사망하였을 경우 혈중 헤모글로빈(Hb)-일산화탄소(CO) 농도는 생존 당시의 화재의 유형을 가늠할 수 있으며 촉진제를 사용한 급격한 화재의 경우 열기와 유독가스로 인해 재실자의 생존은 화재진행속도와 비례되어 체내 Hb-CO 농도는 낮았으며, 훈소와 같이 서서히 진행되는 연소의 경우 오랜 시간 호흡하면서 체내에 축적되는 CO 농도는 증가하였다. 이러한 인체의 Hb-CO 농도를 분석하면 생존 시 어떠한 형태의 화재에 노출되었는지 알 수 있다. 휘발유로 분신한 자살의 경우를 포함해 훈소성 화재사에 이르기까지 Hb-CO 농도는 3 %에서 최고 93 %로 다양한 농도를 보였다.

• 한국물환경학회지
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• 제36권1호
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• pp.55-68
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• 2020

Because of the intensified environmental problems such as climate change and resource depletion, sewage treatment technology focused on energy management has recently attracted attention. The conversion of primary sludge from the primary sedimentation tank and excessive sludge from the secondary sedimentation tank into biogas is the key to energy-positive sewage treatment. In particular, the primary sedimentation tanks recover enriched biodegradable organic matter and anaerobic digestion process produces methane from the organic wastes for energy production. Such technologies for minimizing oxygen demand are leading the innovation regarding sewage treatment plants. However, sewage treatment facilities in Korea lack core technology and operational know-how. Actually, the energy potential of sewage is higher than sewage treatment energy consumption in the sewage treatment, but current processes are not adequately efficient in energy recovery. To improve this, it is possible to apply chemically enhanced primary treatment (CEPT), high-rate activated sludge (HRAS), and anaerobic membrane bioreactor (AnMBR) to the primary sedimentation tank. To maximize the methane production of sewage treatment plants, organic wastes such as food waste and livestock manure can be digested. Additionally, mechanical pretreatment, thermal hydrolysis, and chemical pretreatment would enhance the methane conversion of organic waste. Power generation systems based on internal combustion engines are susceptible to heat source losses, requiring breakthrough energy conversion systems such as fuel cells. To realize the energy positive sewage treatment plant, primary organic matter recovery from sewage, biogas pretreatment, and co-digestion should be optimized in the energy management system based on the knowledge-based operation.

• 한국자동차공학회논문집
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• 제19권5호
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• pp.134-142
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• 2011

Although combustion is essential in most energy generation processes, it is one of the major causes of air pollution. Exhaust pipes with circular fin were designed to study the effect of cooling the recirculated exhaust gases (EGR) of Diesel engines on the chemical composition of the exhaust gases and the reduction in the percentages of pollutant emissions. The gases examined in this study were oxides of nitrogen (NOx), carbon dioxide ($CO_2$) and carbon monoxide (CO). In addition, $O_2$ concentration in the exhaust was measured. The designs adopted in this study were about exhaust pipes with solid and hollow fins around them direct surface force measurement in water using a nano size colloidal probe technique. The direct force measurement between colloidal surfaces has been an essential topic in both theories and applications of surface chemistry. As particle size is decreased from micron size down to true Carbon nano Colloid size (<10 nm), surface forces are increasingly important. Nano particles at close proximity or high solids loading are expected to show a different behavior than what can be estimated from continuum and mean field theories. The current tools for directly measuring interaction forces such as a surface force apparatus or atomic force microscopy (AFM) are limited to particles much larger than nano size. This paper use Water and CNC fluid at normal cooling system of EGR. Experimental result showed all good agreement at Re=$2.54{\times}10^4$ by free convection and Re=$3.36{\times}10^4$ by forced air furnace.

• 한국화재소방학회논문지
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• 제24권2호
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• pp.89-96
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• 2010

본 연구에서는 건축외장재로 많이 사용되고 있는 알루미늄복합패널의 화재위험성을 평가하기 위하여 외장재 실물 연소실험을 실시하였다. 그 결과 알루미늄복합패널의 빠른 화재확산을 보였으며, 이는 알루미늄 복합패널에 내장된 폴리에틸렌이 연소되면서 화염의 수직확산이 급격히 일어난 것이다. 본 실험에서 알루미늄복합패널의 최고 열방출률은 1,144kW로 나타났으며, 열전대에 의해 측정된 표면온도는 알루미늄의 용융점인 $660^{\circ}C$를 넘는 최고 $903.3^{\circ}C$ 이상 상승하였다. 그러므로 알루미늄복합패널의 화재는 상층으로의 급격한 연소확대나 개구부를 통한 내부로의 화재확산에 의한 큰 피해를 줄 수 있을 것으로 판단된다. 이러한 실물실험에서 얻어낸 결과는 향후 알루미늄복합패널의 모델링 구현과 비교함으로써 알루미늄복합패널의 화재 확산 예측에 적용 될 수 있을 것이다.

• 한국세라믹학회지
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• 제41권1호
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• pp.62-68
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• 2004

본 연구에서는 SHS 공정에 의하여 기공의 크기를 조절함으로서 전기저항 발열 특성을 가지는 다공성 $MoSi_2$를 제조하는 공정에 관하여 연구하였다. 결함이 억제된 다공질 재료를 제조하기 위하여 Si 함량 변화 및 예열 공정을 실시하였으며, 성형체 제조에 사용되는 Mo 분말의 크기 변화에 따른 가공 형성 거동에 대하여 연구하였다. 실험 결과 합성된 $MoSi_2$ 입자의 크기는 Mo 입자의 크기와는 관계없이 연소 합성시 발열되는 발열양에 의해 좌우되었으며, 기공의 크기는 Mo 입자의 크기에 따라 결정되었다. 또한 가공 경사 $MoSi_2$ 다공질 재료를 만들기 위하여 150-300${\mu}m$ Mo 분말과 4-5${\mu}m$ Mo 분말을 단계별로 5층으로 혼합하여 합성한 결과 거시적으로 순차적인 기공 크기 분포를 나타내었으며, 이를 통하여 포집 효율등이 우수한 다공성 발열체 재료의 제조가 가능하였다.

• 한국분무공학회지
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• 제25권1호
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• pp.21-26
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• 2020

The objective of this work is to numerically reveal the effect of equivalence ratio change on the simultaneous reduction of NO_X and soot emissions from the simulated-EGR compression ignition engine containing CO₂. An experiment was conducted by using a single-cylinder common-rail injection system engine, an intake control system, and exhaust emissions analyzers. The numerical analysis results were validated under the same experimental conditions. To investigate the effect of equivalence ratio by simulated-EGR containing CO₂, the O₂, N₂, and CO₂ mole fraction were changed in the initial air conditions to the cylinder. The results were analyzed in terms of peak cylinder pressure, indicated mean effective pressure, indicated specific nitrogen oxide, and indicated specific soot. It was revealed that ignition delay characteristics and heat release rate (ROHR) characteristics were not significantly different according to the equivalence ratio. However, as the equivalence ratio increased from 0.68 to 0.83, the maximum combustion pressure and IMEP decreased by about 6.5% and 9.4%, respectively. In the case of ISFC, as is well known, the trend is opposite of IMEP. In the case of ISNO, as the equivalence ratio increased, less NO was generated, and as the equivalence ratio increased by 0.05, the ISSoot value of about 10% increased.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part2
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• pp.1203-1204
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• 2006

Cu-$TiB_2$ nanocomposite powders were synthesized by combining high-energy ball-milling of Cu-Ti-B mixtures and subsequent self-propagating high temperature synthesis (SHS). Cu-40wt.%$TiB_2$ powders were produced by SHS reaction and ball-milled. The milled SHS powder was mixed with Cu powders by ball milling to produce Cu-2.5wt.%$TiB_2$ composites. $TiB_2$ particles less than 250nm were formed in the copper matrix after SHS-reaction. The releative density, electrical conductivity and hardness of specimens sintered at $650-750^{\circ}C$ were nearly 98%, 83%IACS and 71HRB, respectively. After heat treatment at 850 to $950^{\circ}C$ for 2 hours under Ar atmosphere, hardness was descedned by 15%. Our Cu-$TiB_2$ composite showed good thermal stability at eleveated temperature.

• 한국수소및신에너지학회논문집
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• 제14권3호
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• pp.229-235
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• 2003

A 50W class MCFC stack was operated in order to test a new design of the circular shaped separator. in the new design, the anode gas was supplied into the stack and was exhausted out of the stack after the anode reaction. The exhausted gas was reacted with the cathode gas supplied with excess oxygen in the vessel in which the stack was placed. Then the reacted gas flowed into the cathode side of the stack and was exhausted through the outlet located in the center of the stack. The average voltage of the single cells in the stack was 0.835V under the current density of $150mA/cm^2$, initially, and the degradation rate of the stack voltage was 1.7%/1,000h. High stack voltage with good stability of the present stack was due to the small temperature gradient in the stack. The small temperature gradient as well as the easiness of temperature control was the result of the new configuration of the separator which utilized the heat of the combustion reaction between anode outlet gas and the cathode inlet gas for heating the stack.