• 한국표면공학회지
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• 제42권3호
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• pp.139-144
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• 2009

A microwave plasma torch at the atmospheric pressure by making use of magnetrons operated at the 2.45 GHz and used in a home microwave oven has been developed. This electrodeless torch can be used to various areas, including industrial, environmental and military applications. Although the microwave plasma torch has many applications, we in the present work focused on the microwave plasma torch operated in pure steam and several applications, which may be used in future and right now. For example, a high-temperature steam microwave plasma torch may have a potential application of the hydrocarbon fuel reforming at one atmospheric pressure. Moreover, the radicals including hydrogen, oxygen and hydroxide molecules are abundantly available in the steam torch, dramatically enhancing the reaction speed. Also, the microwave plasma torch can be used as a high-temperature, large-volume plasma burner by injecting hydrocarbon fuels in gas, liquid, and solid into the plasma flame. Finally, we briefly report treatment of soils contaminated with oils, volatile organic compounds, heavy metals, etc., which is an underway research in our group.

• 한국분무공학회지
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• 제9권4호
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• pp.31-37
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• 2004

This paper presents spray and combustion characteristics of hydrocarbon fuel injected from pressure-swirl nozzles. Three commercial nozzles with orifice diameters of 0.256, 0.308 and 0.333mm and injection pressures ranging from 0.7 to 1.3 MPa were selected f9r the experiments. Spray characteristics such as breakup length. spray angle and drop size (SMD) were analyzed using photo image analyses and Malvern Panicle Size Analyzer. The drop size was measured with and without a blower at the same measuring locations. The flame length and width were measured using photo image analyses. The temperature distribution along the axial distance and the gas emission such as CO, $CO_2\;and\;NO_x$ were studied. The breakup length decreased with an increase in injection pressure for each nozzle but increased with an increase in nozzle orifice diameter. The spray angle increased and SMD decreased with an increase in injection pressure. The flame with an increased linearly with an increase in injection pressure and in nozzle orifice diameter. The flame temperature increased with an increase in injection pressure but decreased along the axial distance. The maximum temperatures occurred closer to the burner exit and flame at axial distance of 242mm from the diffuser tip. The experimental results showed that the level of CO decreased while that of $CO_2\;and\;NO_x$ increased with an increase in injection pressure and nozzle orifice diameter.

• 한국환경과학회지
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• 제11권4호
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• pp.375-382
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• 2002

The total hydrocarbon distribution of oil products obtained from the pyrolysis of four kinds of mixtures of polyethylene-polystyrene waste has been studied by multidimensional chromatography(high performance liquid chromatography followed by capillary gas chromatography)/mass spectrometry. Saturated, unsaturated and aromatic hydrocarbons in oil products were selectively pre-separated according to structural groups by HPLC and the weight fraction of each group was estimated by analysis of each component using GC-FID response factors. The hydrocarbon distribution of aliphatic fraction consists of $C_{5}$ to $C_{25}$ saturated and unsaturated hydrocarbons. And that of aromatics fraction consists of benzene, toluene, xylene, styrene, propenyl benzene, naphthalene, and some of derivatives. Pyrolysis temperature did not affect the ratio of total weight fraction of aliphatic over aromatic hydrocarbon distribution in case of PS only and PE-PS mixtures (1:1 and 1:4 wt. ratio) as a feed while affected the ratio of total wt. fraction in case of PE only. The optimal temperature for the maximum oil production was $600^{\circ}C$ for pyrolysis of PS and 1:1 and 1:4 mixtures of PE and PS. The optimal condition for aromatic recovery was $600^{\circ}C$ with 1:1 mixture of PE and PS. In this condition, aromatic was produced up to 90% of total oil product. The maximum yield of toluene, xylene, styrene, and propenyl benzene were 8.6, 8.9, 51.0 and 7.4% of feed for pyrolysis PS at $700^{\circ}C$, respectively. However, only 1.3% naphthalene was recovered at $700^{\circ}C$ with 1:1 PE:PS(by wt.).

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 추계학술대회
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• pp.127-132
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• 2003

A study of high-pressure n-heptane droplet vaporization is conducted with emphasis placed on equilibrium at vapor-liquid interface. General frame of previous rigorous model[1] is retained but tailored for flash equilibrium calculation of vapor-liquid interfacial thermodynamics. The model is based on complete time-dependent conservation equations with a full account of variable properties and vapor-liquid interfacial thermodynamics. The influences of high-pressure phenomena, including ambient gas solubility, thermodynamic non-ideality, and property variation on the droplet evaporation are investigated. The governing equations and associated moving interfacial boundary conditions are solved numerically using a implicit scheme with the preconditioning method and the dual time integration technique. And a parametric study of entire droplet vaporization history as a function of ambient pressure, temperature has been conducted. Some computational results are compared with Sato's experimental data for the validation of calculations. For low ambient temperatures, the droplet lifetime first increases with pressures, then decreases for high pressures. For higher ambient temperatures, the droplet lifetime increase with less amplitude than that of low ambient temperatures, which then decreases with more amplitude than that of low temperatures. The solubility of nitrogen can not be neglected in the high pressure and it becomes higher as the pressure goes up.

• 한국해양환경ㆍ에너지학회지
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• 제3권3호
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• pp.34-40
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• 2000

지용성 용존 유기물을 해수로부터 효율적으로 추출할 수 있는 고체상 추출 (solid phase extraction)장치를 새로이 고안하였다. 본 장치는 octadecyl silane (ODS) cartridge와 압력 평형 마개, 96 multifolder, 아스피레타 형 진공 펌프로 구성하였다. 본 장치는 기존의 액체-액체 추출법보다 회수 효율은 1.4 배 이상 증대시켰으며, 최소 시료량을 8 배 이상 감소 시켰다. 따라서 용매의 사용을 5 배 이상 감소시킬 수가 있으므로 나중에 사용된 용매를 제거하는 노력도 크게 감소시켰다. 뿐만 아니라 96 개의 시료(각 1ℓ)를 동시에 처리할 수 있으므로 지용성 용존 유기물의 추출 과정을 반자동화시킨 획기적인 장치이다. 본 장치를 통하여 황해 해수 시료에서 추출된 용존 탄화수소의 정성 및 정량 분석 결과 본 장치가 효율성과 신뢰성에서 기존의 액체-액체 추출법을 대체할 수 있을 것으로 사료된다.

• 한국식품저장유통학회지
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• 제31권2호
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• pp.210-217
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• 2024

This study aimed to compare the quality of smoked fish products processed with liquid smoke with and without pre-cooking when stored at room temperature (25℃) for 0, 2, 4, and 6 days. The observations included moisture content, water holding capacity, color, and total plate and mold counts. The treated samples were also analyzed for polyhydroxyaromatic hydrocarbons (PAHs) at day 0. The study found that the pre-cooked products had a lower moisture content (55.1%) than the control (59.9%) during storage. Additionally, the pre-cooked product had a higher water holding capacity than the control. The TPC value indicates that the pre-cooked product meets the Indonesian standard for smoked fish up to the 2nd day of storage, whereas the control product only meets the standard on day 0. However, the total mold of the control products meets the Indonesian standard until the 2nd day of storage, while the pre-cooked products only meet the standard on day 0. The pre-cooked product had a higher lightness value (L^*) than the control. The analysis of polyhydroxy aromatic hydrocarbon (PAH) showed that the pre-cooking process did not affect the concentration of PAH.

• 한국항공우주학회지
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• 제32권3호
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• pp.66-73
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• 2004

탄화수소 계열의 액체로켓엔진용 연료로서의 액화천연가스의 특성을 성분 및 함량 분석, 냉각제로서의 특성과 엔진 성능 인자로서 특성속도와 비추력 관점에서 평가하였다. 액화천연가스내의 메탄의 함량이 연료로서의 특성을 결정짓는 주요한 인자이었으며, 재생냉각형 액체로켓엔진의 연료로 사용되기 위해서는 최소 90% 이상의 메탄 함량이 요구되는 것으로 판단된다. 한편, 예비 냉각에 의한 액화천연가스의 일부 성분의 응결이 예상되어 정상적인 엔진 작동을 방해하는 요소가 될 수 있다. 약 90%의 메탄 체적 함량을 가지는 액화천연가스의 액체로켓엔진의 작동 조건은 화학 당량비적 혼합비로 표준화한 추진제 혼합비로 0.75가 최적이었다.

• Biotechnology and Bioprocess Engineering:BBE
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• 제11권3호
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• pp.245-250
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• 2006

The effects of aliphatic hydrocarbons (n-hexadecane and n-dodecane) on the volumetric oxygen mass transfer coefficient $(k_L\;a)$ were studied in flat alveolar airlift reactor and continuous stirred tank reactors (CSTRs). In the flat alveolar airlift reactor, high aeration rates (>2vvm) were required in order to obtain efficient organic-aqueous phase dispersion and reliable $k_La$ measurements. Addition of 1% (v/v) n-hexadecane or n-dodecane increased the $k_La$ 1.55- and 1.33-fold, respectively, compared to the control (superficial velocity: $25.8{\times}10^{-3}m/s$, sparger orifice diameter: 0.5 mm). Analysis of the gas-liquid interfacial area a and the liquid film mass transfer coefficient $k_L$ suggests that the observed $k_La$ increase was a function of the media's liquid film mass transfer. Addition of 1% (v/v) n-hexadecane or n-dodecane to analogous setups using CSTRs led to a $k_La$ increase by a factor of 1.68 and 1.36, respectively (superficial velocity: $2.1{\times}10^{-3}m/s$, stirring rate: 250 rpm). These results propose that low-concentration addition of oxygen-vectors to aerobic microbial cultures has additional benefit relative to incubation in purely aqueous media.

• 한국화재소방학회논문지
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• 제32권5호
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• pp.15-21
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• 2018

본 연구에서는 인화성 액체가 비닐바닥에 뿌려져 화재가 발생되었을 때의 성장 특성 및 탄화 패턴 등을 해석하는데 있다. 아세톤은 화염이 착화되고 약 0.2 s 경과되었을 때 화염이 최성기에 도달하였다. 화염은 난류 패턴이며, 연기의 색상은 흰색이었다. 연소가 진행되는 하단은 층류 패턴이 확인되었고, 상단 부분은 난류 패턴이다. 연소 완료된 바닥은 희미한 포어 패턴을 나타냈다. 벤젠은 착화 후 약 0.6 s 경과하였을 때 강렬한 화염이 생성되었고, 길이는 약 50 mm로 측정되었다. 화염이 쇠퇴기로 접어들었을 때 불완전 연소에 의한 다량의 검은색 연기가 발생하였다. 연소가 완료된 바닥면의 탄화 패턴은 포어 패턴 및 스플래시 패턴 등이 확인되었다. 알코올은 착화되어 약 1.1 s 경과하였을 때 강렬한 화염이 형성되었다. 또한 인화성 액체가 고인 곳은 탄화 심도가 크게 형성되었고, 인화성 액체가 흘러간 곳의 경계면에서 탄화의 흔적이 확인되었다.

• International Journal of Automotive Technology
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• 제7권4호
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• pp.407-413
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• 2006

The liquefied petroleum gas(LPG), mixture of propane and butane, has the potential to reduce toxic hydrocarbon emissions and inhibit ozone formation due to its chemical composition. Conventional mixer systems, however, have problems in meeting the future lower emission standards because of the difficulty in controlling air-fuel ratio precisely according to mileage tar accumulation. Liquid Phase LPG injection(LPLi) system has several advantages in more precise fuel metering and higher engine performance than those of the conventional mixer type. On the other hands, leakage problem of LPLi system at the injector tip is a main obstacle for meeting more stringent future emission regulations because these phenomena might cause excessive amount of THC emission during cold and hot restart phase. The main focus of this paper is the development of a leaked fuel recirculation system, which can eliminate the leaked fuel at the intake system with the activated carbon canister. Leaked fuel level was evaluated by using a fast response THC analyzer and gas chromatography. The result shows that THC concentration during cold and hot restart stage decreases by over 60%, and recirculation system is an effective method to meet the SULEV standard of the LPLi engine.