• 대한기계학회논문집B
• /
• 제38권10호
• /
• pp.807-815
• /
• 2014

본 연구는 최근 대형고로에 도입된 PCI 시스템에서 석탄의 탄종에 따른 연소 특성을 파악하기 위해, 고로내 석탄의 연소환경을 잘 모사할 수 있는 층류반응기(LFR)을 이용하여 화염형상을 분석하고, 체류시간별 입자의 온도와 배기가스인 CO와 $CO_2$를 측정하였다. 화염형상의 가시적인 분석뿐만 아니라, 입자온도와 배기가스의 배출특성을 근거로 하여 휘발분 연소와 촤 연소 구간을 구분하였다. 특히 CO는 고로내 발생하는 산화철의 환원반응에 영향을 주는 인자로써, 본 연구에서는 탄종별 CO의 배출시점과 특성에 대한 분석이 이루어졌다. 휘발분 함량이 많은 탄종의 연소 초기 입자온도는 높게 측정되었지만, 휘발분 연소구간이 길어지면서 이후에 연속적으로 시작되는 촤 연소가 지연되었다. 촤 연소구간에서는 연료비가 높을수록 CO발생량이 상대적으로 많고, 적정온도가 유지되었다.

• 대한환경공학회지
• /
• 제33권3호
• /
• pp.196-201
• /
• 2011

본 연구는 최근 들어 대도시 대기오염물질의 주요 배출원 중 하나로 대두되고 있는 음식점 고기구이로부터 배출되는 미세먼지의 배출 특성에 대하여 연구한 것이다. 본 연구에서는 돼지고기와 소고기의 구이 시 발생되는 미세 입자상물질의 배출특성을 파악하기 위해 고기구이 시 발생되는 미세먼지를 효과적으로 채취할 수 있는 고기구이 챔버를 제작하였으며, 다단충돌식 입경분립기와 광산란식의 미세먼지 측정기를 사용하였다. 연구 결과 다단충돌식 입경분립기를 사용하여 측정한 미세먼지 농도 결과에서는 전반적으로 돼지고기의 경우가 소고기보다 높게 나타났다. 미세먼지의 입경분포 특성을 살펴본 결과 돼지고기와 소고기 모두 $1.95{\sim}3.2{\mu}m$의 입경에서 가장 높은 농도를 나타냈다. 고기 1 kg당 배출되는 미세먼지의 배출계수는 돼지생고기, 돼지양념고기, 소생고기, 소양념고기에서 각각 1.36 g/kg, 1.03 g/kg, 1.23 g/kg과 0.92 g/kg으로 나타났다. 광산란식 측정기를 사용하여 측정한 결과에서는 돼지고기와 소고기 모두 $1.6{\sim}2.5{\mu}m$와 $2.5{\sim}3.5{\mu}m$ 입경에서 가장 높은 농도로 나타나 $2.5{\mu}m$를 중심으로 높은 농도로 나타난 다단충돌식 결과와 유사한 특성을 보였다. 광산란식에 의해 측정된 배출계수는 돼지생고기, 돼지양념고기, 소생고기, 소양념고기에서 각각 3.37 g/kg, 2.76 g/kg, 2.93 g/kg과 2.77 g/kg으로 나타나 다단충돌식 결과보다 2배에서 3배 이상 높게 측정되었다. 또한 $PM_{2.5}/PM_{10}$의 비는 돼지생고기, 돼지양념, 소생고기, 소양념고기에서 각각 0.56, 0.58, 0.56 그리고 0.58로 나타나 중량농도에서도 $PM_{2.5}$가 많음을 알 수 있었다. 중량농도를 입자의 비중을 1로 가정하여 산출한 개수농도로 환산한 결과를 보면 다단충돌식 입경분립기로 측정한 결과는 $10^{19}$개로 나타났고, 광산란식으로 측정한 결과에서는 $10^{16}$개 수준으로 나타나 다단충돌식 입경분립기의 경우에서 보다 높은 것으로 나타났다.

• 한국자동차공학회논문집
• /
• 제19권5호
• /
• pp.76-81
• /
• 2011

Exhaust gas recirculation is the well-known and widely used NOx reduction technology for diesel engines. More effective EGR cooler has been developed and applied to diesel engines to meet the reinforced emission regulation. However, the contaminated EGR cooler by diesel exhaust gas reduces the performance of the engine and NOx reduction rate. The buildup of deposits in EGR coolers cause significant degradation in heat transfer performance, often on the order of 20~30%. Deposits also increase pressure drop across coolers and thus may degrade engine efficiency under some operation conditions. In this study, as a solution for this problem, DOC assisted EGR cooler is designed and then investigated to reduce fouling and its impact on cooler performance. A single channel EGR cooler fouling test apparatus and soot particle generator were developed to represent the real EGR cooler and exhaust gas of diesel engine. EGR cooler effectiveness of the case with catalyst of pt 30g/ft3 decreased just up to 5%. This value was 45% less compared to the case without catalyst which decreased up to 9% after 10hours experiments.

• 천문학회보
• /
• 제44권2호
• /
• pp.54.3-54.3
• /
• 2019

During the formation of large-scale structures in the universe, shocks with the sonic Mach number Ms <~ 5 are naturally induced by supersonic flow motions of baryonic matter in the intracluster medium (ICM). Cosmic rays (CRs) are expected to be accelerated via diffusive shock acceleration (DSA) at these ICM shocks, although the existence of CR protons in the ICM remains to be confirmed through gamma-ray observations. Based on the results obtained from kinetic plasma simulations, we build an analytic DSA model for weak, quasi-parallel shocks in the test-particle regime. With our DSA model, the CR acceleration efficiency ranges ~ 0.001 - 0.02 in supercritical quasi-parallel shocks with sonic Mach number Ms ~ 2.25 - 5, and the acceleration would be negligible in subcritical shocks wth Ms <~ 2.25. Adopting our DSA model, we estimate gamma-ray and neutrino emissions from clusters of galaxies by performing cosmological hydrodynamic simulations. The estimated gamma-ray flux is below the Fermi-LAT upper limit. In addition, the possible neutrino emission due to the decay of charged pions in galaxy clusters would be about <~ 1% of the atmospheric neutrino intensity in the energy range of <~ 100 GeV. In this talk, we will discuss the implication of our results.

• Journal of Advanced Marine Engineering and Technology
• /
• 제36권4호
• /
• pp.484-489
• /
• 2012

본 논문은 선박의 주 추진기관으로 사용가능한 육상 운송수단에 탑재되어있는 대형 디젤엔진에서 배출되는 입자상 물질과 질소산화물의 배출특성을 ESC mode에 적용시켜 분석하는데 초점을 두었다. 입자상 물질은 엔진의 고부하 영역에서 다량으로 배출되는 특성을 확인 할 수 있었으며 질소산화물의 경우 배기가스 온도 측정형태와 동일한 경향으로 배출되었다. 매연여과장치를 부착하여 입자상 물질의 배출특성을 분석한 결과 mode별 1/100~1/1,000배까지 저감되었다. 그러나 급격한 엔진 부하 변동 시 저감효과는 떨어졌으며 고속-고부하 영역에서는 매연여과장치내부의 온도상승으로 일부 재생현상이 발생하여 입자상 물질의 배출 증가 결과를 초래하는 현상이 발생하였다. 시험엔진에서 배출되는 입자상 물질의 입경분포를 분석한 결과 대부분 100nm 이하의 크기를 가지는 나노 입자가 배출되었으며 매연여과장치를 부착 및 탈착하여 측정한 결과 배출수준에는 차이가 있지만 입자상 물질의 입경분포는 비슷한 경향으로 분석되었다.

• 분석과학
• /
• 제15권5호
• /
• pp.433-438
• /
• 2002

국제원자력기구로부터 제공받은 2종 (V-50, P-50)의 인공적으로 준비된 여과지상의 도시분진시료중의 미량원소를 중성자방사화분석법을 사용하여 비파괴 분석하였다. 중성자방사화분석의 품질관리를 위해 미국표준기술원의 인증표준물질 (Urban Particulate Matter, NIST SRM1648)이 사용되었으며 여과지상의 분진시료에서는 약 20종의 원소를 분석하였다. 측정결과는 실험실간 비교 및 숙련도 평가를 위하여 중성자방사화분석법, 하전입자유도 X-선 방출분광법, 유도결합플라즈마 질량분석법 등을 이용한 세계 40개국, 49개 실험실의 분석값들과 함께 통계처리 되었다. 통계 처리한 결과, 본 실험실의 분석값들의 Z-score가 ${\pm}2$ 이내에 들어오는 결과를 얻었으며, 숙련도 시험도 분석된 모든 원소의 정확도와 정밀도가 기준에 통과되는 신뢰성 있는 결과를 얻어 현재 수행하고 있는 대기분진시료들의 분석품질관리가 적합함을 입증하였다.

• 한국대기환경학회지
• /
• 제22권3호
• /
• pp.353-360
• /
• 2006

This study identified a particle size distribution (PSD) of fine particulate matter and emission characteristics of V and Ni by the comparison between anthropogenic sources of oil combustion (industrial boiler, oil power plant, etc.) and lab-scale combustion using a drop-tube furnace. In oil combustion source, the mass fraction of fine particles (less than 2.5 micrometers in diameter) was higher than that of coarse particles (larger than 2.5 micrometers in diameter) in $PM_{10}$ (less than 10 micrometers in diameter) as like in lab-scale oil combustion. In addition to this, it was identified that ultra-fine particles (less than 0.1 micrometers in diameter) had a large distribution in fine particles. Toxic metals like V and Ni had large mass fractions in fine particles, and most of all was distributed in ultra-fine particles. Most of ultra-fine particles containing toxic metals have been emitted into ambient by combustion source because it is hard to control by the existing air pollution control device. Hence, we must be careful on these pollutants because it is obvious that these are associated with adverse health and environmental effect.

• 한국환경과학회지
• /
• 제20권1호
• /
• pp.147-153
• /
• 2011

The objectives of this study were to investigate the seasonal characteristics of metallic and ion elements of $PM_{10}$(Particulate matter with aerodynamic diameter ${\leq}10\;{\mu}m$) and the effects of vessels exhaust emission from ships harboring in Busan City. The $PM_{10}$ samples were collected from January 2010 to October 2010 at Dongsam-dong(coastal area), in Busan City. The particulate matters were analyzed for major water soluble ionic components and metals. The ranges of the $PM_{10}$ mass concentrations were from 29.8 ${\mu}g/m^3$ to 47.0 ${\mu}g/m^3$ in Dongsam-dong. The $PM_{10}$ mass concentrations in Dongsam-dong are very similar to Gwangbok-dong during same sampling periods. These results were understood by the effects of the shipping source emitted from ships anchoraging and running. The concentrations of water-soluble ions and metals in the $PM_{10}$ had a level of as high as the order of $SO_4^{2-}$>$NO_3^-$>$Cl^-$ and $NH_4^+$>$Na^+$>$Ca^{2+}$>$K^+$>$Mg^{2+}$, respectively. The correlation coefficients($R^2$) for $SO_4^{2-}/PM_{10}$ and $NH_4^+/PM_{10}$ of were 0.7446 and 0.7784, respectively, and it showed the high correlation with each other.

• 한국분말재료학회지
• /
• 제12권3호
• /
• pp.167-173
• /
• 2005

Production of weakly agglomerated nanopowders with the characteristic size of about 10 nm and a narrow particle size distribution is still a topical problem especially if the matter is an acceptable output (>50 g/hour), a high purity of the final product, and a low (energy consumption. The available experience and literature data show that the most promising approach to production of such powders is the evaporation-condensation method, which has a set of means for heating of the target. From this viewpoint the use of pulsed electron accelerators for production of nanopowders is preferable since they allow a relatively simple adjustment of the energy, the pulse length, and the pulse repetition rate. The use of a pulsed electron accelerator provides the following opportunities: a high-purity product; only the target and the working gas will interact and their purity can be controlled; evaporation products will be removed from the irradiation zone between pulses; as a result, the electron energy will be used more efficiently; adjustment of the particle size distribution and the characteristic size of particles by changing the pulse energy and the irradiated area. Considering the obtained results, we developed a design and made an installation for production of nanopowders, which is based on a hollow-cathode pulsed gas-filled diode. The use of a hollow-cathode gas-filled diode allows producing and utilizing an electron beam in a single chamber. The emission modulation in the hollow cathode will allow forming an electron beam 5 to 100 ms long. This will ensure an exact selection of the beam energy. By now we have completed the design work, manufactured units, equipped the installation, and began putting the installation into operation. A small amount of nanopowders has been produced.

• 농촌계획
• /
• 제19권4호
• /
• pp.137-147
• /
• 2013

Most of livestock houses are concentrated in certain area with mass rearing system resulting in rapid spread of infectious diseases such as HPAI (highly pathogenic avian influenza). The livestock-related vehicles which frequently travel between farms could be a major factor for disease spread by means of transmission of airborne aerosol including pathogens. This study was focused on the quantitative measurement of aerosol concentration by field experiment while vehicles were passing through the road. The TSP (total suspended particle) and PM10 (particle matter) were measured using air sampler with teflon filter installed downward the road with consideration of weather forecast and the direction of road. And aerosol spectrometer and video recorders were also used to measure the real-time distribution of aerosol concentration by its size. The results showed that PM2.5 was not considerable for transmission of airborne aerosol from the livestock-related vehicle. The mass generated from the road during the vehicle movement was measured and calculated to 241.4 ${\mu}g/m^3$ by means of the difference between TSP and PM2.5. The dispersion distance was predicted by 79.6 m from the trend curve.