• 한국미생물·생명공학회지
• /
• 제25권3호
• /
• pp.235-239
• /
• 1997

Chlorococcum littorale has been grown in high $CO_2$ concentrations to utilize $CO_2$ gas in the polluted air. The effect of incident light intensity on the specific growth rate is expressed by a photoinhibition model, showing half- saturation constant, $K_0\;as\;8\;(W/m^2)$ and inhibition constant, Ki as 35 $(W/m^2)$. The maximum specific growth rate was also estimated as 0.095 (1/day) under this condition. This strain maintained the optimum growth rate in 20% of $CO_2$ gas but 50% of input $CO_2$ gas is the maximum concentration considering the economical efficiency. The maximum Specific $CO_2$ consumption rate, $qCO_2$ was measured as 17.48 (mg $CO_2/g$ dry wt./day) in batch cultivation, 11.2 (mg $CO_2/g$ dry wt./day) in fed-batch cultivation and 10.87 (mg $CO_2/g$ dry wt./day) at 0.065 (1/day) of dilution rate in continuous cultivation. The chemical composition of the biomass obtained from this process showed 32.5% of protein, 27.5% of lipid, 16.5% of carbohydrate and ash 11.7%.

• Nuclear Engineering and Technology
• /
• 제52권8호
• /
• pp.1650-1660
• /
• 2020

Comparing with the large containment, the gas can not flow freely within the local compartment due to the small volume of the compartment in case of serious accident, which affects the hydrogen flow distribution, and it will determines the location where high concentration occurs in compartment. In this paper, hydrogen distribution and possible hydrogen risk in the vessel under the different conditions are investigated. The results show that when the initial gas momentum is increased, the ability of gas enters into the upper region of the vessel will be strengthened, and the hydrogen volume fraction in the upper region of the vessel is higher. Comparing with horizontal source direction, when source direction is vertically towards upper space, hydrogen is more likely to accumulate in the upper region of the vessel. With the increasing of steam mass flow, the dilution effect of steam on the hydrogen volume fraction will be strengthened, while the pressure in the vessel is also increased. When steam flow is decreased, the hydrogen explosion risk is higher in the vessel. The experiment data can provide technical support for the validation of the CFD software and the mitigation of hydrogen risk in the containment compartment.

• Journal of Korean Vacuum Science & Technology
• /
• 제4권2호
• /
• pp.55-60
• /
• 2000

Vertically aligned carbon nanotubes on nickel coated glass substrates were obtained at low temperatures below 600$\^{C}$ by plasma enhanced hot filament chemical vapor deposition where acetylene gas was used as the carbon source and ammonia gas was used as the dilution gas and catalyst. The diameters of the nanotubes decreased from 96 m to 41 m as NH$_3$/C$_2$H$_2$ ratio increased from 2:1 to 5:1. Total flow rate of input gases with constant NH$_3$/C$_2$H$_2$ ratio did not change the diameter of carbon nanotubes. No growth of the carbon nanotubes was observed with only C$_2$H$_2$ nor N$_2$ instead of NH$_2$. G line and D line in Raman spectra were observed, which implies that there were many structural defects in carbon nanotubes.

• 한국연소학회지
• /
• 제20권4호
• /
• pp.19-25
• /
• 2015

An experimental study was conducted to find the effect of a pilot flame on the flammability of inert-gas-diluted methane and propane. The diffusion pilot flame was formed with propane at the innermost nozzle of a concentric triple co-flow burner. The main diffusion flame was formed with nitrogen-diluted methane or propane at the outermost nozzle of the burner. An air flow was located in-between. The results showed that the existence of the pilot flame helped stabilizing the main flame even at the flammability limit concentration of nitrogen-diluted fuel. The co-flow burner generated re-circulation zones and local variation of equivalence ratio depending on the flow rates of the reactants, which are known to help flame stabilization. Hot-wire experiments confirmed that both heating of the reactants and supplying of active chemical species by the pilot flame contributed to stabilization of the main flame. The results of this study would suggest a design concept for an efficient SVRU system that minimizes the emission of unburned hydrocarbon fuel from ship fuel tanks.

• 한국세라믹학회지
• /
• 제50권6호
• /
• pp.446-450
• /
• 2013

TRISO coated particles with a ZrC barrier layer were fabricated by a fluidized-bed chemical vapor deposition (FBCVD) method for a use in a very high temperature gas-cooled reactor (VHTR). The ZrC layer was deposited by the reaction between $ZrCl_4$ and $CH_4$ gases at $1500^{\circ}C$ in an $Ar+H_2$ mixture gas. The amount of free carbon codeposited with in ZrC was changed by controlling the dilution gas ratio. Near-stoichiometric ZrC phase was also deposited when an impeller was employed to a $ZrCl_4$ vaporizer which effectively inhibited the agglomeration of $ZrCl_4$ powders during the deposition process. A near-stoichiometric ZrC coating layer had smooth surface while ZrC containing the free carbon had rough surface with tumulose structure. Surface roughness of ZrC increased further as the amount of free carbon increased.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2008년도 추계학술대회B
• /
• pp.1979-1983
• /
• 2008

The effects of carbon dioxide addition to oxygen have been investigated with swirl-stabilized premixed methane flame in a laboratory-scale pre-mixed combustor. The methane fuel and oxydant mixture gas ($CO_2$ and $O_2$) were mixed in a pre-mixer and introduced to the combustor through different degrees of swirl vanes. The flame characteristics were examined for different amount of carbon dioxide addition to the methane fuel and different swirl strengths. The effects of carbon dioxide addition and swirl intensity on the combustion characteristics of pre-mixed methane flames were examined using chemiluminescence techniques to provide information about flow field. The results show that the flame area increases at upstream of reaction zone because of increase in recirculation flow for increase in swirl intensity. The flame area is also increased at the downstream zone by recirculation flow because of increase in swirl intensity which results in higher centrifugal force. The OH and CH radical intensity of reaction zone decrease with carbon dioxide addition because the carbon dioxide plays a role of dilution gas in the reaction zone.

• Food Science and Biotechnology
• /
• 제15권4호
• /
• pp.572-577
• /
• 2006

The physiochemical interactions of 1-methylcyclopropene (1-MCP) and adsorbing agents can be described using a very powerful tool, inverse gas chromatography (IGC). Sorption behavior of 1-MCP on various adsorbing agents was assessed using the profile peaks of 1-MCP at an infinite dilution concentration using the IGC technique. Chromatogram peaks of 1-MCP adsorption were not observed for the adsorbing agent activated carbon. The forms of sorption isotherms followed Henry's law, and behaved according to the binding site theory. Specific retention volume and distribution coefficients for 1-MCP on the adsorbing agents were determined at 50, 60, 70, and $80^{\circ}C$, respectively. Silica gel had a much higher number of binding sites for 1-MCP compared to Tenax-TA and activated clay agents. Meanwhile, activated carbon proved to be a very strong binding agent for 1-MCP based on 1-MCP efficiency experiments on the selected adsorbing agents. However, as a proper means of delivering 1-MCP molecules to fresh food products, activated carbon is not fit for the binding and release of 1-MCP gas under dry or high humidity conditions because activated carbon has a strong affinity for 1-MCP, even when treated with distilled water.

• 한국항공우주학회지
• /
• 제41권8호
• /
• pp.632-638
• /
• 2013

본 논문에서는 네덜란드 부게넘 및 국내 태안 IGCC플랜트의 석탄으로부터 생성된 합성가스의 화염안정성 및 연소불안정성에 대해 기술하였다. GE7EA 모사 가스터빈 연소기를 대상으로 상압 고온 연소시험을 수행하여 입열량 및 질소희석에 따른 연소특성을 관찰하였다. 시험결과를 통해 화염안정화 선도는 화염의 구조에 따라 Regime I부터 VI까지 6개의 영역으로 구분하였고, 2개의 영역(Regime I, II)에서 화염이 안정적으로 연소되는 것을 확인하였다. 태안 및 부게넘 합성가스 모두 안정하게 연소되고, 화염이 외부 재순환 유동과 결합되는 Regime II에 해당하는 것을 확인하였다. 또한 $H_2$/CO비만을 고려하면 수소의 함량이 높은 부게넘 가스가 안정적 연소구간이 넓지만, 질소희석을 고려할 때 부게넘 가스 내의 더 많은 질소가 화염안정성에 부정적 영향을 미치기 때문에 태안 합성가스가 부게넘 합성가스보다 더 안정적으로 연소하였다.

• 한국식품과학회지
• /
• 제39권4호
• /
• pp.366-371
• /
• 2007

어육장의 휘발성 향기 성분들을 용매추출을 이용하여 분리, 농축하였으며, GC-MS로 분석하였다. 총 36가지의 휘발성 성분들이 검출되었으며, 11개의 aliphatic hydrocarbons, 4개의 acids, 2개의 ketones, 5개의 phenols, 7개의 alcohols, 1개의 pyrazine, 4개의 pyrones와 furanones, 2개의 miscellaneous components 등으로 구성되어 있었다. 특히, acids인 butanoic acid가 높은 함량을 나타내었다. 어육장의 향기활성 성분을 규명하기 위해 용매추출을 이용하여 휘발성 성분들을 분리 후 향추출물 희석분석법으로 flavor dilution(FD) $factor(Log_3$ FD)를 구하였다. 이 결과 어육장에서 총 20종의 향기활성 성분들이 확인되었다. 이 중 군덕내의 특성을 지닌 butanoic acid와 구운 감자향을 지닌 methional이 높은 FD factor를 보였으며, 이들 성분 외에 높은$(Log_3$ FD>7)를 나타내는 성분들로는 2-methyl-2-butanol(soysauce-like), 3-hydroxy-2-butanone(buttery), 2-furanmethanol(burnt sugar-like) 등이 있었다. 본 실험에서는 어육장을 시료로 하여 휘발성 향기성분 및 향기활성 성분들을 GC-MS 및 AEDA법에 의해 분석함으로 어육장 특유의 향미특성을 규명하였다. 이는 앞으로 고급화된 장류 제품으로서는 물론, 다양한 식품에서 조미소재로의 어육장의 활용도를 높이는데 기여할 것이다.

• 한국식품과학회지
• /
• 제40권5호
• /
• pp.497-502
• /
• 2008

감동젓무 김치의 발효기간에 따른 휘발성 향기 성분들을 SAFE를 이용하여 분리한 후, GC-MS로 분석하였다. 총 57가지의 휘발성 성분들이 검출되었으며, 14개의 S-containing compounds, 22개의 terpene hydrocarbons, 13개의 aliphatic hydrocarbons, 4개의 alcohols, 4개의 miscellaneous components 등으로 구성되어 있었다. 동정된 휘발성 성분들 중 S-containing compound류와 terpene hydrocarbon류가 정량적으로 주요 성분들로 나타났으며, 이들 중 dimethyldisulfide, methyl-2-propenyldisulfide, dimethyltridulfide, di-2-propenyltrisulfide, 2-vinyl-[4H]-1,3-dithiin 등의 함량이 전체적으로 높게 나타났으며, 저장 기간에 따라서는 시료간에 정성적으로 뚜렷한 차이를 나타내지 않았다. 감동젓무 김치의 향기활성 성분을 규명하기 위해 용매추출을 이용하여 휘발성 성분들을 분리 후 향추출물 희석분석법으로 flavor dilution(FD) factor($Log_3$ FD)를 구하였다. 이 결과 감동젓무 김치에서 총 15종의 휘발성 향기활성 성분들이 확인되었다. 이 중 군덕내의 특성을 지닌 4-isothiocyanato-1-butene과 썩은 양파향을 주는 dimethyldisulfide가 높은 FD factor를 보였으며, 이들 성분 외에 높은 FD factor($Log_3$ FD>5)를 나타내는 성분들로는 2-vinyl-[4H]-1,3-dithiin($Log_3$ FD factor 5, spicy/garlic-like)이 있었다.