• 한국연소학회지
• /
• 제21권1호
• /
• pp.38-45
• /
• 2016

Flame characteristics and NO emission behavior in $CH_4$/air-air premixed counterflow flames with applying FIR and FGR with $CO_2$ and $H_2O$ were investigated numerically by varying the ratios of FIR and FGR as well as global strain rate. Chemical effects of added $CO_2$ and $H_2O$ via FIR and FGR were analyzed through comparing flame characteristics and NO behaviors from real species($CO_2$ and $H_2O$) with those from their artificial species($XCO_2$ and $XH_2O$) which have the same thermochemical, radiative, and transport properties to those for the real species. The results showed that flame temperature and NO emission with FIR varied much more sensitively than that with FGR. Those varied little irrespective of adding $CO_2$, $H_2O$, and their artificial species to the fuel stream via FIR. However, Those were varied complicatedly by chemical effects of added $CO_2$ and $H_2O$ via FGR. Detailed analyses for them were made and discussed.

• 유체기계공업학회:학술대회논문집
• /
• 유체기계공업학회 2002년도 유체기계 연구개발 발표회 논문집
• /
• pp.482-485
• /
• 2002

Development projects in KAIST rotted to the micro thermal device is introduced. Multi disciplinary research team is composed by combustion group and semiconductor group in KAIST and catalyst research center in KRICT to develop micro thermal/fluidic device and various items are on development. Among the projects, various kind of componenst that is required by the micro thermal devicesystem is introduced. Technology related to development of micro combustor, Micro igniter, micro fabrication of 3D structure, micro reactor and micro catalyst preparation is introduced.

• 한국대기환경학회지
• /
• 제22권5호
• /
• pp.590-603
• /
• 2006

Size-and time-resolved aerosol samples were collected using an eight-stage Davis rotating unit for monitoring (DRUM) sampler from 23 March to 29 April 2001 at Gosan, Jeju Island, Korea, which is one of the super sites of Asia-Pacific Regional Aerosol Characterization Experiment(ACE-Asia). These samples were analyzed using synchrotron X-ray fluorescence for 3-hr average concentrations of 19 elements including Al, Si, S, Cl, K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, As, Se, Br, Rb, and Pb. The size-resolved data sets were then analyzed using the positive matrix factorization(PMF) technique to identify possible sources and estimate their contributions to particulate matter mass. PMF analysis uses the uncertainty of the measured data to provide an optimal weighting. Twelve sources were resolved in eight size ranges($0.09{\sim}12{\mu}m$) and included continental soil, local soil, sea salt, biomass/biofuel burning, coal combustion, oil combustion, municipal incineration, nonferrous metal source, ferrous metal source, gasoline vehicle, diesel vehicle, and volcanic emission. The PMF result of size-resolved source contributions showed that natural sources represented by local soil, sea salt, continental soil, and volcanic emission contributed about 79% to the predicted primary particulate matter(PM) mass in the coarse size range ($1.15{\sim}12{\mu}m$) while anthropogenic sources such as coal combustion and biomass/biofuel burning contributed about 58% in the fine size range($0.56{\sim}2.5{\mu}m$). The diesel vehicle source contributed mostly in ultra-fine size range($0.09{\sim}0.56{\mu}m$) and was responsible for about 56% of the primary PM mass.

• Elastomers and Composites
• /
• 제47권4호
• /
• pp.355-363
• /
• 2012

2,2-Bis(3-amino-4-hydroxyphenyl)hexafluoropropane 와 방향족 디이미드-디카르복실산을 thionyl chloride, triethyl amine 및 NMP 하에서 직접 중축합하여 trifluoromethyl group을 포함하는 일련의 poly(hydroxyamide)s(PHAs)를 제조 하였다. PHAs은 $35^{\circ}C$ DMAc 용액에서 0.54-0.96 dL/g의 고유점도를 보였다. 모든 PHAs은 여러 종류의 유기용매에 쉽게 용해되었으나, PBOs은 황산에 부분적으로 용해되는 것을 제외하고, 전혀 용해되지 않았다. PHAs은 열적고리화 반응에 의해서 흡열과 함께 PBOs로 전환되었다. PHAs의 최대 중량손실온도는 $559-567^{\circ}C$의 영역을 보였고, poly(benzoxazole imide)s(PBOs)은 47-59%의 비교적 높은 char 수득율을 보였다. PBOs의 Pyrolysis Combustion Flow Calorimeter(PCFC) 결과에서 12-19 W/g의 HRR 과 2.7-3.6 kJ/g의 total HR을 보였다. PBO 1의 HRR은 PBO 3 의 HRR (19 W/g)보다 37 % 낮은 12 W/g의 가장 낮은 값을 보였다.

• 한국가스학회지
• /
• 제26권3호
• /
• pp.27-37
• /
• 2022

최근 ESS(전기저장장치)의 보급이 늘어나면서 ESS에 의한 지속적인 화재발생으로 인명 및 재산의 피해 또한 급증하고 있다. ESS에 활용되는 우레탄 샌드위치 패널에 제조에 있어 난연 성능의 향상이 필요한 실정이다. 본 연구에서는 연질 폴리우레탄 폼의 난연 특성을 구현하고자 제품의 물성을 변화시키는 이소시아네이트 관능기 파라미터의 변화로 인한 제품의 조직 치밀도가 화재성능에 미치는 영향을 연구하였다. 우레탄 조직의 치밀도를 변화시켜가며 제품을 제작하여 연소성능 시험, 가스유해성 시험, 연기밀도 시험을 진행하였다. 그 결과 총 방출열량은 이소시아네이트 관능기 그룹이 높은 경우 성능이 우수하고, 최대 열 방출율과는 상관이 없는 것을 확인하였다. 이소시아네이트 관능기 그룹의 값이 2.7이상에서 형상의 붕괴를 방지할 수 있었다. 가스유해성 시험에서는 이소시아네이트 관능기 그룹이 상대적으로 높아 조직이 치밀하면서 탄화 막 형성이 용이한 Char시스템용 난연제가 추가적으로 투입되어야 성능이 상승하였고, 연기밀도 시험에서는 이소시아네이트 관능기 그룹의 값이 2.75이상에서 성능이 증가되는 것을 확인하였다. 따라서 본 연구의 결과로 기존에 사용되던 저렴한 우레탄 샌드위치 패널을 대체할 난연제 개발에 기반을 마련할 수 있을 것으로 생각된다.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2001년도 춘계학술대회논문집D
• /
• pp.878-883
• /
• 2001

The effects of external excitation with various frequencies and amplitudes on the flame behavior and pollution emission characteristics from a laminar jet flame are experimentally investigated. Measurements of $NO_{x}$ emission indices($EINO_{x}$), performed in unconformed and vertical lifted flame at resonance frequency by strong excitation, have been conducted experimentally. It was also conducted to investigate the effects of excited frequency on $NO_{x}$ emissions with a various frequency ranged 0Hz to 2kHz. From the vertical lifted flame like turbulent of the excited jet with resonance frequency was shown that the dependence of $NO_{x}$ emission could be categorized into three groups: Group 1 of intermediate flame length and relative narrow flame volume yielding low $NO_{x}$ emission, Group 2 of short flame length but large flame volume yielding high $NO_{x}$ emission and Group 3 of long flame length with low temperature contours yielding high $NO_{x}$ emission.

• 한국입자에어로졸학회지
• /
• 제17권4호
• /
• pp.125-132
• /
• 2021

Fresh PM_2.5 smokes emitted from combustion of four biomass materials (pellet, palm fruit fiber (PFF), PKS, and sawdust) in a laboratory-controlled environment were characterized using an attenuated total reflectance-fourier transform infrared (ATR-FTIR) technique. In smoke samples emitted from combustion of pellets, PFF and PKS, which is being used as boiler fuels for greenhouses in rural areas, the organic carbon/elemental carbon (OC/EC) ratios in PM_2.5 were very high (14.0-35.5), whereas in sawdust smoke samples they were significantly low (<4.0) due to the combustion method close to flaming combustion. ATR-FTIR analysis showed that OH(3400-3250 cm^-1), CH₃(2958-2840 cm^-1), CH₂(2910 cm^-1 and 2850 cm^-1), ketone(1726-1697 cm^-1), C=C(1607-1606 cm^-1 and 1515-1514 cm^-1), lignin (1463-1462 cm^-1 and 1430-1428 cm^-1) and -NO₂(1360-1370 cm^-1) peaks were identified in all biomass burning (BB) smoke samples. However, additional peaks appeared depending on the type of biomass. Among the four types of biomass materials, an additional peak of the methylene group CH₃(2872-2870 cm^-1) appeared only in PFF and PKS smoke samples, and a peak of C=O(1685 cm^-1) was also confirmed. And in the case of PKS smoke samples, a peak of aromatic C=C(1593 cm^-1 and 1476 cm^-1) that did not appear in other BB samples was also observed. This indicates that the molecular structure of organic compounds emitted during BB differs depending on the type of biomass materials. The results of this study are expected to provide valuable information to more specifically reveal the effect of BB on PM_2.5 collected in the atmospheric environment.

• Nuclear Engineering and Technology
• /
• 제56권1호
• /
• pp.132-140
• /
• 2024

In the event of a severe accident in Sodium Cooled Fast Reactors (SFR), the sodium combustion aerosols along with fission product aerosols would migrate to the environment through leak paths of the Reactor Containment Building (RCB) concrete wall under positive pressure. Understanding the characteristics of sodium aerosol transport through concrete leak paths is important as it governs the environmental source term. In this context, experiments are conducted to study the influence of various parameters like pressure, initial mass concentration, leak path diameter, humidity etc., on the transport and deposition of sodium aerosols in straight leak paths of concrete. The leak paths in concrete specimens are prepared by casting and the diameter of the leak path is measured using thermography technique. Aerosol transport experiments are conducted to measure the transported and plugged aerosol mass in the leak paths and corresponding plugging times. The values of differential pressure, aerosol concentration and relative humidity taken for the study are in the ranges 10-15 kPa, 0.65-3.04 g/m³ and 30-90% respectively. These observations are numerically simulated using 1-Dimensional transport equation. The simulated values are compared with the experimental results and reasonable agreement among them is observed. From the safety assessment view of reactor, the approach presented here is conservative as it is with straight leak paths.

• 한국연초학회지
• /
• 제13권2호
• /
• pp.5-20
• /
• 1991

For the quality enhancement of harvested-year leaf tobacco to the quality of 2-year naturally aged leaf tobacco, cellulose and nicotine degradative bacteria were isolated and identified. Effects of artificial fermentation treated cellulase and nicotine degradative bacteria on the quality of leaf tobacco were investigated from the chemical and sensory points of view. 1, Changes in chemical composition of leaf tobacco resulted from the addition of cellulase extracted from Cellulomonas sp. [3ml(${\mu}{\textrm}{m}$ D-glucose/ml. mil-1) of enzymes solution 11009 of leaf tobacco] and nicotine degradative bacteria, Pseudomonas sp. 2ml(IX109 cells$\div$ 100g of leaf tobacco), and subsequently fermented at 40${\mu}{\textrm}{m}$$^{\circ}C$, 65% R. H. for 40 days are as follows : 1) Content of crude fiber decreased 12% It took 9 min, 53 sec. to reach full combustion in control group but took only 7 min. 47 sec. in the treated group, taking almost equal time to 2-year naturally aged leaf tobacco(7 min. 35sec.). 2) Light intensity of control group was 60.96% with bright lemon color but that of treated leaf tobacco accounted for 47.69 with orange to dark brown color series, which was almost equal to the value, 45.69, of 2-year naturally aged leaf tobacco. 3) Linoleic acid, serving mild taste among organic acids, amounted to 1.llmg/g in control group but increased to 1.35m9/9 in the treated leaf tobacco, identical to the content(1.35mg/g) of 2-year naturally aged leaf tobacco. 4) Content of solanone, on of the typical leaf tobacco flavor compounds, accounted for 2.95% in control group but increased to 2.87% in treated group. 5) Methyl furan, useful flavor compound in smoke composition, accounted for 17.6$\mu\textrm{g}$/cig. in control group but increased to 25.9$\mu\textrm{g}$/cig. in treated group. However, acroleine decreased from 69.3$\mu\textrm{g}$/cig. in control group to 58.6$\mu\textrm{g}$/cig. in treated group 2. In sonsory test, mild taste evaluation of control group scored 5.47 and treated group 7.93 which was evaluted almost equal to the value(8.00) of 2-year naturally aged leaf tobacco. Aroma evaluation of control group scored 5.60, treated group 8.20, and 2-year naturally aged leaf tobacco 8.33. In addition, total harmony taste of control group showed 5.67, treated group 8.07 (p<0.01), and 2-year naturally aged leaf tobacco 8.00. From these results, it can be said that quality of treated leaf tobacco is not inferior to that 2-year naturally aged leaf tobacco.

• 대한기계학회논문집B
• /
• 제35권4호
• /
• pp.439-444
• /
• 2011

새 가스그룹의 가스기기 호환성 시험가스 결정을 위해 현 13A 가스그룹의 시험가스와 13A 가스기기의 가스호환성(효율 포함) 관계를 실험적으로 규명하였다. 이 시험결과로부터 새 가스그룹의 불완전 연소 및 화염 부상 한계 가스는 각각 새 가스그룹의 웨버지수 상한보다 2 % 크고, 하한 보다는 1 % 작은 값이 적정함을 알 수 있었다. 또한 효율 시험용 R 가스의 조성은 메탄 96 mol %와 프로판 4 mol %가 가장 적정하며, 일반 효율 시험시에는 공급 천연가스도 R가스로 사용될 수 있음을 확인하였다. 그리고 역화 한계 가스 내 수소 농도는 기존 30 vol %에서 EN437과 같이 23 vol %로 낮출 수 있는 것으로 분석되었다.