• Bulletin of the Korean Chemical Society
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• v.34 no.1
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• pp.139-142
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• 2013

A study was carried out to evaluate the solid phase micro-extraction (SPME) for formaldehyde emission analysis of uncoated plywood. In SPME, formaldehyde was on-fiber derivatized through headspace extraction and analyzed by gas chromatography coupled with mass spectrometry (GC/MS). The SPME was compared with desiccators (DC-JAS 233), small-scale chamber (SSC-ASTM D6007) and liquid-liquid extraction (LLE-EPA 556) methods which were performed in accordance with their respective standards. Compared to SSC (RSD 4.3%) and LLE (RSD 5.0%), the SPME method showed better repeatability (RSD 1.8%) and not much difference from DC (RSD 1.4%). The SPME has proven to be highly precise (at 95% confidence level) with better recovery (REC 102%). Validation of the SPME method for formaldehyde quantitative analysis was evidenced. In addition, the SPME by air sampling directly from plywood specimens (SPME-W) correlated best with DC ($r^2$ = 0.983), followed by LLE ($r^2$ = 0.950) and SSC ($r^2$ = 0.935).

• Food Science and Biotechnology
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• v.18 no.3
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• pp.700-705
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• 2009

In this study, the volatile compounds in 9 commercial fermented soybean pastes were extracted and analyzed by headspace-solid phase microextraction (HS-SPME) and gas chromatography-mass spectrometry (GC-MS), respectively. A total of 63 volatile components, including 21 esters, 7 alcohols, 7 acids, 8 pyrazines, 5 volatile phenols, 3 ketones, 6 aldehydes, and 6 miscellaneous compounds, were identified. Esters, acids, and pyrazines were the largest groups among the quantified volatiles. About 50% of the total quantified volatile material was contributed by 5 compounds in 9 soybean paste samples; ethyl hexadecanoate, acetic acid, butanoic acid, 2/3-methyl butanoic acid, and tetramethyl-pyrazine. Three samples (CJW, SIN, and HAE) made by Aspergillus oryzae inoculation showed similar volatile patterns as shown in principal component analyses to GC-MS data sets, which showed higher levels in ethyl esters and 2-methoxy-4-vinylphenol. Traditional fermented soybean pastes showed overall higher levels in pyrazines and acids contents.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.1
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• pp.89-93
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• 2012

c-BN films were deposited on SKH-51 steels by electron assisted hot filament CVD method and microstructure development was studied processing parameters such as bias voltage, temperature, etching and phase transformation at boundary layer between BN compound and steel to develop a high performance wear resistance tools. A negative bias voltage higher than 200V at substrate temperature of $800^{\circ}C$ and gas pressure of 20 torr in B2H6-NH3-H2 gas system was one of optimum conditions to produce c-BN films on the SKH-51 steels. Thin layer of hexagonal boron nitride phase was observed at the interface between c-BN layer and substrate.

• Journal of Advanced Marine Engineering and Technology
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• v.23 no.2
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• pp.252-258
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• 1999

As an effective means to convey crushed materials from seabed to on board ship and to raise hazardous or abrasive liquids air-lift pump provides a reliable mechanism due to its simple config-uration and easy-to-operate principle. The present study is focused on fundamental investigation of related performance by the analysis program based on the gas-liquid two-phase flow in circular pipes. The program covers pump operating in isothermal and vertical two-phase flow with Newto-nian liquids. it is summarized as important result that an optimum air mass flow rate exists for the maximum lifted liquid mass flow rate in terms of a given submergence rates and furthermore attachment of downcomer gives little effects on riser performance the conveyed liquid flow rate increases with larger submergence rate.

• Bulletin of the Korean Chemical Society
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• v.18 no.9
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• pp.985-994
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• 1997

The reaction of gas-phase atomic hydrogen with hydrogen atoms chemisorbed on Fe(110) surface is studied by use of classical trajectory procedures. Flow of energy between the reaction zone and bulk solid phase has been treated in the generalized Langevin equation approach. A London-Eyring-Polanyi-Sato energy surface is used for the reaction zone interaction. Most reactive events are found to occur in strong single-impact collisions on a subpicosecond scale via the Eley-Rideal mechanism. The extent of reaction is large and a major fraction of the available energy goes into the vibrational excitation of H2, exhibiting a vibrational population inversion. Dissipation of reaction energy to the heat bath can be adequately described using a seven-atom chain with the chain end bound to the rest of solid. The extent of reaction is not sensitive to the variation of surface temperature in the range of Ts=0-300 K in the fixed gas temperature, but it shows a minimum near 1000 K over the Tg=300-2500 K.

• Bulletin of the Korean Chemical Society
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• v.12 no.6
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• pp.678-681
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• 1991

The Wittig-oxy-Cope rearrangements of deprotonated diallyl ether, I, $CH_2={\bar{C}}H-CH-O-CH_2-CH=CH_2$, have been investigated theoretically by the AM1 method. A two step mechanism forming a Wittig product ion, II, $(CH_2=CH)$ $(CH_2=CH-CH_2)$ $CHO^-$, through a radical-pair intermediate was found to provide the most favored reaction pathway in the Wittig rearrangement. The subsequent oxy-Cope rearrangement from species II also involves a two step mechanism through a biradicaloid intermediate. The intramolecular proton transfer in I (to form $CH_2=CH-CH_2-O-{\bar{C}}H-CH=CH_2$) is a higher activation energy barrier process compared to the Wittig and oxy-Cope rearrangements and is considered to be insignificant. These results are in good agreement with the condensed-phase as well as gas-phase experimental results.

• Journal of the Korean Institute of Gas
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• v.7 no.3 s.20
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• pp.32-43
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• 2003

As this paper is observed the phase equilibrium diagram of mono- (methane) and multi-component(natural gas) hydrates, and the hydrate growth behavior is analysed and compared by the experiments during the reaction. The difference of mono and multi-component hydrates is an induction delay time and a plateau region. And the concentration of component of gases is changed during the reaction in multi-component hydrates and the concentration of components is changed during the decomposition of hydrate according to each decomposing rates of gases. At 6 MPa, 276.65 K and 600 rpm, the induction delay time of multi-component hydrate formation is observed shorter than that of mono-component hydrate formation because the hydrate nuclei of gases except methane form faster than those of methane. And the plateau region of mono-component hydrate is observed distinctly at 0.055 mole of $CH_4$/mole of water and that of multi-component hydrate is observed at 0.04 mole of $CH_4$/mole of water.

• 한국신재생에너지학회:학술대회논문집
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• 2007.06a
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• pp.519-523
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• 2007

Gas(or methane) hydrates are solid solutions when water molecules are linked through hydrogen bonding and create host lattice cavities that can enclose a large variety of guest gas molecules. The natural gas hydrate crystal may exist at low temperature above the normal freezing point of water and high pressure greater than about 30 bars. A lot of quantities of natural gas hydrates exists in the earth and many production schemes are being studied. In the present investigation, depressurization method was considered to predict the production of gas and the simulation of the two phase flow - gas and water - in porous media is being carried out. The simulation show about the fluid flow in porous media have a variety of applications in industry. Results provide the appearance of gas and water production, the pressure profile, the saturation of gas/ water/ hydrates profiles and the location of the pressure front.

• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.10 no.6
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• pp.62-72
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• 1996

In this paper, ozonizer using U-type lamp(Olamp) has been designed and manufactured, which can perform a role of lighting source and ozonizer by using photo and chemical methods. The discharge, spectrum, illuminance, ozone concentration, ozone generation, ozone yield and sterilization characteristics of Olamp have been studied. The important conclusions obtained from this paper can be summa'||'&'||'not;rized as follows. As a result of spectrum characteristics for Olamp, ultraviolet ray of a short wave'||'&'||'not;lengths and a visible ray are radiated. The illuminance of Olamp was found to be useful for "color distinctive and intermittent works in the dark working spaces" in accordance with KS A 3011. The ozone concentration of gaseous phase is inversely proportional to quality of supplied gas. Also, ozone conce tration and generation of gaseous phase are rised more commercial oxygen gas than those trial air gas for constant quality of supplied gas. Ozone generation and ozone yield of gaseous phase are proportion'||'&'||'not;al to ozone concentration of gaseous phase. The characteristics of liquid ozone concentration at distilled water are proportional to circulating velocity of fermentation chamber and ozone concentration of gas'||'&'||'not;eous phase. As a result, the sterilization characteristics of Escherichia coli have been obtained more than 97[ % J.

• The Journal of Engineering Research
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• v.6 no.1
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• pp.97-109
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• 2004

The synthesis and crystal structure of amorphous calcium carbonate obtained from gas-liquid reaction of CaO-$C_2 H_5 OH$-$CO_2$ system according to change of added amount of calcium oxide by blowing $CO_2$ gas and reaction time using ethanol and ethylene glycol were investigated by electric conductivity, X-ray diffraction, and scanning electron microscope. The powdery or gelatinous phases were prepared by passing $CO_2$ gas at a flow rate of 1$\ell$/min into the suspensions containing 10~40g of CaO in mixing solutions 900ml of $C_2 H_5 OH$- and 100ml of ethylene glycol. By rapid filtration and drying the both phases at $60^{\circ}C$ under reduced pressure, the phases converted to the spherical vaterite and amorphous phase. The stable phase of amorphous calcium carbonate(ACC) was formed in the region pH 7-9 but the formation regions of amorphous phase were remarkably affected by pH in the mother liquor. It seems that a part of ACC changed into chain calcite as an intermediate products. The initial reactants prior to the formation of precipitated calcium carbonate is ACC. And ACC is unstable in the aqueous solution and crystallizes finally to calcite by the through-solution reaction. Especially ACC was produced or gelatinous phase which precipitated from the reaction of CaO-$C_2 H_5 OH$-$CO_2$ system.