• 한국자동차공학회논문집
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• 제9권4호
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• pp.77-84
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• 2001

Measurements of local CO, $CO_2$, $O_2$, $N_2$, $C_3$H$_{8}$, NOx concentrations and flame temperature are made for partially premixed flame with and without acoustic excitation. The CO, $CO_2$, $O_2$, $N_2$, and $C$_3$H_8$ concentrations are determined by thermal conductivity detection (Gas-chromatograph) and NOx concentrations are determined by chemiluminescent detection (NOx analyser). To measure local sample concentration, sampling probe was made by quartz with inlet diameter of 0.25mm. In the case of excitation, the visual shape of the flame is changed from laminar flame to turbulent-like flame. The flame length is also reduced, and the flame width becomes broad. In the observation of emission concentration without acoustic excitation, meanwhile, the $CO_2$ and NOx concentrations peak at flame front where the mixture meets with surrounding air, and the CO concentration is increasing at maximum position of CO2 concentration and peaks at the centerline of the burner. In the case of acoustic excitation, the $CO_2$ concentration is widely occurred at nozzle of the burner and is higher relative to unexcitation. The CO concentration is much reduced, but NOx concentration is more increasing. And flame temperature is higher relative to unexcitation. These are caused by enhancing of mixing with surrounding air due to excitation. However, in the case of acoustic excitation, the total NOx concentration is reduced because of the shortened flame length which affects residence time.e.

• 한국대기환경학회지
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• 제18권6호
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• pp.539-546
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• 2002

The physicochemical properties of solid wastes generated from seven highway service areas, four branch offices, and one construction site were analyzed in concert with air pollutants including heavy metals emitted from near-by small-scale incinerators. The amount of solid wastes generated from highway areas has been increasing with recent increases in the number of highways and passengers. Twelve incinerators examined in this study generally had capacity smaller than 100 kg/hr, most of which were equipped with cyclone for dust removal. It was seen that the concentrations of the gas-phase air pollutants (e.g., SO$_2$, NO$_{x}$, HCl and H$_2$S) were above the acceptable emission standards except one or two sites. CO concentrations at all incinerators were also higher due to incomplete combustion. In addition, particulate matters showed concentration six times higher at their maximum. The results of heavy metal analysis showed that the concentrations of Cu, Cd, and Ni satisfied the emission standards. whereas Pb at one site and Zn at five sites exceeded the standards. Cr measurement results indicated that 9 of 12 incinerators had higher values than the standard; especially one branch office showed nine times higher than normal concentration. In order to satisfy more stringent emission standards in the near future, it is necessary to install air pollution control system and to develop an intensified management plan.n.

• 한국자동차공학회논문집
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• 제14권1호
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• pp.129-137
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• 2006

This paper studies the effects of the swirl for the variation of intake port configuration that is key parameters in the flow field of direct injection diesel engines. In-cylinder flow characteristics is known to have significant effects on air-fuel mixing, combustion, and emissions. To investigate the effects of the swirl flow, various rpm(250, 500, 750) and two different intake port were used. And to evaluate the swirl motion in the flow field visualization engine, steady state flow test was conducted. Helical port intake port and SCV(Swirl Control Valve) were selected as the design parameters to increase the swirl flow and parametric study was performed. In the case of non-SCV, intake flow rate and non-dimensional swirl ratio were higher than those of SCV for the swirl head type. So, we could strengthen the swirl in the flow field with the swirl head type and don't using SCV. From the results of steady state flow test, non-swirl head type has the most good advantage for intake flow rate, and also the flow rate could be increased by using the SCV slightly. The effects of the type of engine head on intake air flow capability are dominant with respect to the existence of the SCV. We could measure the qualitative grade of swirl by capturing the scattering signal of microballoon from ICCD camera in the visualization diesel engine.

• 한국화재소방학회논문지
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• 제19권3호
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• pp.58-63
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• 2005

등유 풀화재의 화염과 연소에 의해 생성되는 연기의 특성에 대해서 조사하였다. 다양한 발열량을 위해 직경을 변하게 할 수 있는 팬버너를 제작하였다. 풀화재를 조사하기 위해 화염 높이와 떨림 주파수를 분석하였다. 실험적으로 풀화염 높이는 이론적 상관관계 증가율과 잘 일치하지만, 정량적으로는 등유의 연소율에 기인하여 과대 평가된 값을 보인다. 연기의 특성을 조사하기 위해 세 가지의 실험방법을 사용하였다. 먼저 가스분석기를 이용하여 연소시 발생되는 주요 가스 농도를 측정하였는데 이산화탄소의 생성과 산소의 소모율은 풀화염의 열방출율에 비례하지만, 일산화탄소의 발생에 대한 경향성은 발견할 수 없었다. 연기의 매연입자를 광감쇄법과 TEM 이미지를 이용하여 특성을 조사하였다 연기밀도는 발열량의 증가에 따라 매우 급격히 증가하였고, 등유 풀화염에서 발생한 매연입자들은 자연적인 연소조건임에도 불구하고 역확산 제트화염에서 생성된 매연과 유사한 형태와 탄화정도를 보임이 관찰되었다.

• 한국전기전자재료학회논문지
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• 제28권1호
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• pp.51-56
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• 2015

The object of this study is to obtain the optimum mix proportion of halogen free compound with flame resistance and, for the purpose, thermal/electrical characteristics test are conducted using compatibilizing agents, flame resistance agents, hydroxide aluminum, sunscreen, antioxidant and silicon oil on the base resin of linear low density polyethylene (LLDPE), Ethylene vinyl acetate copolymer (EVA). Existing compound method accompanies many requirements to be satisfied including a lot of addition of flame resistance agents, prohibition of impact on mixing capability with base and property and etc. In this study, different from the existing method, the optimum mix proportion is determined and experimented by adding nano clay. Oxygen index test shows no difference between specimens while T-6, T-9 shows oxygen index of 29[%] and 26[%], respectively. This is concluded that hydroxide aluminum, which is a flame resistance agent, leads low oxygen index. From UL94-V vertical flame resistance test, the combustion behavior is determined as V-0, Fail based on UL94-V decision criteria. Viscometry shows low measurements in specimens with separate addition of compatibilizing agents or nano clay. Volume resistivity test shows low measurement mainly in specimens without compatibilizing agents. Therefore, with the flame resistance compound shows better performance for thermal/electrical property and the optimum mix proportion are achieved among many existing materials.

• 한국분무공학회지
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• 제25권1호
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• pp.8-14
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• 2020

Recently, 1-D model-based engine development using virtual engine system is getting more attention than experimental-based engine development due to the advantages in time and cost. Injection rate profile is the one of the main parameters that determine the start and end of combustion. Therefore, it is essential to set up a sophisticated model to accurately predict the injection rate as starting point of virtual engine system. In this research, procedure of 1-D model setup based on AMESim is introduced to predict the dynamic behavior and injection rate of diesel injector. As a first step, detailed 3D cross-sectional drawing of the injector was achieved, which can be done with help of precision measurement system. Then an approximate AMESim model was provided based on the 3D drawing, which is composed of three part such as solenoid part, control chamber part and needle and nozzle orifice part. However, validation results in terms of total injection quantity showed some errors over the acceptable level. Therefore, experimental work including needle movement visualization, solenoid part analysis and flow characteristics of injector part was performed together to provide more accuracy of 1-D model. Finally, 1-D model with the accuracy of less than 10% of error compared with experimental result in terms of injection quantity and injection rate shape under normal temperature and single injection condition was established. Further work considering fuel temperature and multiple injection will be performed.

• 한국철도학회논문집
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• 제11권3호
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• pp.294-299
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• 2008

본 연구는 구난역을 갖는 철도 터널 내에서 화재가 발생하였을 때 연기 전파 특성에 미치는 배연효과를 다루고 있다. 터널 화재 실험은 4cm의 정사각형 형태의 n-heptane$(C_7H_{16})$ 풀화재(pool fires)에 대해서 수행되었고 다양한 화재 발생위치에 따른 발열량을 측정하였다. 또한, 본 연구에서는 상용코드인 Fluent(Ver.6.3)를 사용하여 구난역을 갖는 철도 터널 내의 연층 전파 특성을 분석하였으며, MVHS(Modified Volumetric Heat Source) 모델을 사용하여 화재에 의한 연소생성물의 농도 및 거동을 예측하였다. 해석 조건은 다양한 화재 발생 위치에 따라서 측정 된 발열량을 이용하였다. 본 연구를 통해 교행로 내에 위치한 방화문에 의해 비사고터널로의 확산을 막을 수 있음을 보였고 특히, 배연시스템의 가동을 통해 유동방향을 변화시킴으로써 사고터널내의 연기 확산을 제어할 수 있음을 확인하였다.

• 한국해양공학회지
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• 제22권3호
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• pp.82-88
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• 2008

The diesel engine of the merchant ship has been aperated in severe environments more and more, because the temperature of the exhaust gas of a combustion chamber is getting higher and higher with increasing use of heavy oil of law quality, due to the significant increase in the price of oil in recent some years. As a result, the degree of wear and corrosion between exhaust valve and seat ring is more serious compared to other engine parts. Thus the repair welding of exhaust valve and seat ring is a unique method to prolong the life of the exhaust valve, from an economical point of view. In this study, the corrosion property of both weld metal and base metal was investigated using electrochemical methods such as measurement of corrosion potential, cathodic and anodic polarization curves, cyclic voltammogram, and polarization resistance in 5% H2SO4 solution. The test specimen was a part of an exhaust valve stem being welded as the base metal, using various welding methods. In all cases, the corrosion resistance as well as hardness of the weld metal zone was superior to the base metal. In particular, plasma welding showed relatively good properties for both corrosion resistance and hardness, compared to other welding methods. In the case of DC SMAW (Shielded metal arc welding), corrosion resistance of the weld metal zone was better than that of the base metal, although its hardness was almost same as the base metal.

• 한국화재소방학회논문지
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• 제34권3호
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• pp.1-7
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• 2020

건축물의 복잡화, 대형화로 인해 합성수지를 건축 재료로써 많이 활용되고 있다. 이에 따라 합성수지가 원인이 되는 화재의 발생이 증가하고 있다. 합성수지 화재의 특성으로는 연기 등 연소생성물로 인한 인명 및 재산피해가 크다는 점이고, 이는 연기생성과 발생과 관계된다. 이에 본 연구는 국내 건축 및 소방관계법령과 연기측정방법에 대해 검토하고, 연기관련 3가지 시험기준(ISO 5660-1, ISO 12136, ASTM E 662)을 바탕으로 실험을 실시하였다. 실험에 대한 결과로 연기생성 관련 데이터에서는 PP 43.27 ㎡, PVC 32.83 ㎡, PMMA 12.33 ㎡ 순으로 나타났고, 연기발생 관련 데이터에서는 PVC 27.855 g, PP 9.599 g, PMMA 6.975 g 순으로 나타났다.

• 한국광물학회지
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• 제23권2호
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• pp.99-106
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• 2010

금번 연구에서는 2009년 1월 1일부터 12월 31일 사이에 대전광역시 유성구 지역에서 확보한 강수 시료를 대상으로 강수에 의한 오염 희석 규명을 시도하였다. 강수여과물에 대해 등온잔류자화(Isothermal remanent magnetization) 측정과 현미경 분석 및 정성적인 화학 성분 분석을 실시하였다. 비강수일에 포집한 먼지 시료와 황사발생일에 채취한 먼지 시료도 비교를 위해 실험에 사용하였다. 자화특성 실험과 현미경 관찰 결과를 바탕으로 판단하면, 강수에서 여과된 고체 시료에 존재하는 자성 물질은 자철석이다. 관찰된 자성 물질의 특이한 형태(구형/타원체형)와 탄소 함유를 고려하면, 인위적인 연소에 의해 형성된 자철석이라 해석된다. 강수에서 여과된 고체 시료의 등온잔류자화는 일반 먼지보다도 낮고 황사에 비해서는 현저히 낮은데, 이는 강수에 의해 발생하는 상당한 양의 자성물질 희석 효과라 판단된다.