• 한국대기환경학회지
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• 제24권3호
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• pp.275-283
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• 2008

Since mobile source is a major source of VOCs, quantifying emissions from motor vehicles is an important factor to control VOCs in atmosphere. In this study, in order to evaluate tailpipe VOCs emissions from motor vehicles, mass emissions of non-methane volatile organic compounds from 45 vehicles were determined. Measurements were made on a chassis dynamometer using CVS-75 mode and speed specific drive modes. Target VOCs are 53 compounds determined as the volatile ozone precursors. The individual VOCs composition of vehicle emission and emission rates were also determined. In case of gasoline vehicles, VOCs emission from over 80,000 km vehicles were about 46% larger than less 80,000 km vehicles. The difference in benzene and toluene according to driving mileage was 44% and 26% respectively. The composition of VOCs were different by fuel type. The order of VOCs composition was paraffins>aromatics>olefins in gasoline vehicle emissions, paraffins>olefins>aromatics in light duty diesel vehicle emissions. The VOCs emissions were decreased as vehicle speed increasing. These results will be used to calculate total VOCs emissions from automobiles in the future.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2006년도 제27회 추계학술대회논문집
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• pp.295-298
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• 2006

메탄/질소-공기 저 신장율 대향류 확산화염에서 화염소화 거동과 에지화염의 진동불안정성에 대한 실험적 연구를 수행하였다. 특히, 저 신장율 화염에서 복사열손실 뿐만 아니라 측면전도 열손실이 현저해 진다. 각 전체 신장율에서 화염진동의 시작조건과 진동모드를 제안하였다. 화염길이는 측면 전도열손실과 밀접한 관계를 가지고 있으며 화염소화와 화염진동에 중대한 영향을 미친다. 저 신장율 에지화염의 진동모드는 성장모드, 감쇠모드 그리고 조화모드로 요약된다. 또한, 각 진동모드의 조건을 전체신장율과 희석제의 몰분율에 대한 안전화선도를 작성하였다.

• Korean Chemical Engineering Research
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• 제44권5호
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• pp.528-534
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• 2006

고온 플라즈마가 적용된 플라즈마트론을 이용하여 바이오가스 개질을 통해 수소를 생산하는데 있어서 최적 운전 조건에 대해 연구하였다. 음식물 쓰레기의 혐기성 발효조에서 생성된 바이오가스 구성비($CH_4/CO_2$)가 1.03, 1.28, 2.12인 바이오가스로 개질실험을 수행하고, 수소 생산과 메탄 전환율을 향상시키기 위해 바이오가스 유량비, 수증기 유량비, 입력전력 변화와 같은 변수별 연구를 수행하였다. 바이오가스 유량비(biogas/TFR : total flow rate), 수증기 유량비($H_2O/TFR$: total flow rate), 입력전력이 각각 0.32~0.37, 0.36~0.42, 8 kW일 때 메탄의 전환율이 81.3~89.6％인 최적운전조건을 보였다. 이때 합성가스 중의 수소와 일산화탄소의 농도는 27.11~40.23％, 14.31~18.61％이며, 수소 수율은 40.6~61％, 에너지 전환율은 30.5~54.4％, $H_2/CO$ 비는 1.89~2.16이다.

• 대한기계학회논문집B
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• 제30권10호
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• pp.996-1002
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• 2006

Experiments in methane-air low strain rate counterflow diffusion flames diluted with nitrogen have been conducted to study the behavior of flame extinction and edge flame oscillation in which flame length is less than the burner diameter and thus lateral conduction heat loss in addition to radiative heat loss could be remarkable at low global strain rates. Critical mole fraction at flame extinction is examined with velocity ratio and global strain rate. Onset conditions of edge flame oscillation and flame oscillation modes are also provided with global strain rate and added nitrogen mole fraction to fuel stream (fuel Lewis number). It is seen that flame length is closely relevant to lateral heat loss, and this affects flame extinction and edge flame oscillation considerably. Edge flame oscillations in low strain rate flames are experimentally described well and are categorized into three: a growing oscillation mode, a decaying oscillation mode, and a harmonic oscillation mode. The regime of flame oscillation is also provided at low strain rate flames. Important contribution of lateral heat loss even to edge flame oscillation is clarified

• 한국수소및신에너지학회논문집
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• 제18권1호
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• pp.12-25
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• 2007

Numerical simulation of the natural gas steam reforming process for on-site hydrogen production in a $H_2$ fueling station was conducted on the basis of process material and heat balances. The effects of reforming parameters on the process efficiency of hydrogen production were investigated, and set-point values of each of the parameters to minimize the sizes of unit process equipments and to secure a stable operability of the reforming process were suggested. S/C ratio of the reforming reactants was found to be a crucial parameter in the reforming process mostly governing both the hydrogen production efficiency and the stable operability of the process. The operation of the process was regarded to be stable if the feed water(WR) as a reforming reactant could evaporate completely to dry steam through HRSG. The optimum S/C ratio was 3.0 where the process efficiency of hydrogen production was maximized and the stable operability of the process was secured. The optimum feed rates of natural gas(NGR) and WR as reforming reactants and natural gas(NGB) as a burner fuel were also determined for the hydrogen production rate of $27\;Nm^3/h$.

• 한국화재소방학회논문지
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• 제34권4호
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• pp.59-68
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• 2020

본 연구에서는 축소모형을 이용한 철도터널의 화재안전성 평가 실험시 필요한 축소모형 철도차량의 화재에 대한 설계를 수행하였다. 기존의 철도터널 축소모형 실험시 활용된 방법의 단점을 극복하기 위하여 화재부력을 위하여서는 메탄올 화원을 이용하였으며, 연기 가시화를 위하여서는 스모크카트리지를 활용하여 철도차량 화재를 모사하였다. 지하철 철도차량의 열방출률의 모사를 위하여 다양한 메탄올 연료 팬에 대하여 콘칼로리미터(ISO 5660) 및 저울을 이용하여 열방출률을 측정하였다. 설계된 축소모형 철도차량 화원을 이용하여 축소모형 철도터널에서의 임계속도를 측정하였다. 화재 임계속도는 축소모형 터널 상부에서의 온도 및 레이져를 이용한 가시화 측정결과 등을 종합적으로 검토하여 선정하였다.

• 대한화학회지
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• 제35권1호
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• pp.3-15
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• 1991

10 torr의 기체 iso-프로필알코올과 0∼1990 torr의 이산화탄소의 혼합기체에 0∼50 kGy의 Co-60감마선을 조사한 후 생성물을 기체크로마토그래프로 분석하여 일산화탄소, 아세톤, 메탄, 에탄, C$_3$H$_a$, C$_4$H$_b$ 및 tert-부틸알코올 등이 생성됨을 알았다. 490 torr 이상의 이산화탄소가 혼합된 시료에서는 G(CO)값 약 4를 얻었다. 아세톤 등 각 유기생성물의 생성속도와 iso-프로필알코올의 분해속도는 이산화탄소의 압력에 비례하여 증가되었는데, 이산화탄소 압력 10 torr 증가당 G-(-iso-Propanol)값은 4, G(Acetone)값은 2씩 증가되었다. 본 실험의 결과를 토대로 iso-프로필알코올과 이산화탄소 혼합기체에서의 방서선에 의한 일산화탄소와 각종 유기물의 생성반응 및 iso-프로필알코올의 분해반응 메카니즘을 고찰하였다.

• 한국표면공학회지
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• 제53권5호
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• pp.241-248
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• 2020

The change of the deposition behavior of diamond through a pretreatment process of the base metal prior to diamond deposition using HFCVD was investigated. To improve the specific surface area of the base material, sanding was performed using sandblasting first, and chemical etching treatment was performed to further improve the uniform specific surface area. Chemical etching was performed by immersing the base material in HCl solutions with various etching time. Thereafter, seeding was performed by immersing the sanded and etched base material in a diamond seeding solution. Diamond deposition according to all pretreatment conditions was performed under the same conditions. Methane was used as the carbon source and hydrogen was used as the reaction gas. The most optimal conditions were found by analyzing the improvement of the specific surface area and uniformity, and the optimal diamond seeding solution concentration and immersion time were also obtained for the diamond particle seeding method. As a result, the sandblasted base material was immersed in 20% HCl for 60 minutes at 100 ℃ and chemically etched, and then immersed in a diamond seeding solution of 5 g/L and seeded using ultrasonic waves for 30 minutes. It was possible to obtain optimized economical diamond film growth rates.

• 유기물자원화
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• 제19권3호
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• pp.63-72
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• 2011

본 연구에서는 benzalkonium chloride 처리에 따라 바이오가스 생산이 억제되는 정도를 평가하였다. 바이오가스 생산 억제 수준은 10 ppm, 40 ppm, 80ppm의 benzalkonium chloride가 처리되었을 때 각각 10%, 30-40%, 70% 이상이었다. Benzalkonium chloride의 처리에 따라 저해되는 효소를 알아내기 위하여 효소 활성을 분석하였으며 산성/알칼리 포스파타아제, 프로테아제는 메탄 생산량과 음의 상관관계를 나타내었다. ${\alpha}$-글루코시다아제는 실험기간 동안 메탄 생성량과 상대적으로 낮은 음의 상관성을 보였으며(p<0.01, r=-426), 다른 효소와의 상관성도 상대적으로 낮았다. 메탄생성률(ml/day)은 benzalkonium chloride및 산성 포스파타아제와 유의한 상관성을 나타내었다. Benzalkonium chloride가 대장균에 미치는 영향을 원판확산법을 통하여 분석하였다. Benzalkonium chloride의 농도가 높을수록 세균증식 억제대가 확장되었으며, 이를 통하여 benzalkonium chloride가 초산생성균의 증식을 억제함으로써 혐기소화조에 영향을 미칠 수 있다는 것을 확인하였다.

• 한국물환경학회지
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• 제35권4호
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• pp.299-307
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• 2019

The purpose of this study was to investigate the effect of low temperature thermal pre-treatment on biodegradation of waste activated sludge for anaerobic digestion as a countermeasure for increasing sludge generation. The experimental condition was accomplished in 2 %, 4 %, and 6 % TS concentration, and $70^{\circ}C$, $80^{\circ}C$, $90^{\circ}C$ of temperature for a maximum of 120 minutes retention time. Then, it was followed by analysis of physical/chemical properties, BMP test and composition of biogas. The biogas characteristic was evaluated by applying the modified Gomperz model. As a result, solubility of dissolved substrate, such as $SCOD_{Cr}$, soluble carbohydrate, and soluble protein, and biogas production increased as temperature increased. Solubilization efficiency at $90^{\circ}C$ was 18.4 %, 17.03 % and 16.88% in 2 %, 4 %, and 6 % TS concentration respectively. Also, solubilization rates of carbohydrate and protein similarly increased. BMP test results also showed that methane production in excess sludge increased to 0.194, 0.187 and $0.182m^3/kg$ VS. respectively, and lag phase decreased to 0.145, 0.220, 0.351 day due to acceleration of the hydrolysis step. Consequently, low-temperature thermal pre-treatment could increase biodegradability of sludge, positively affecting biogas production and sludge reduction.