• Korean Journal of Acupuncture
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• v.17 no.1
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• pp.11-17
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• 2000

Induction of phase II enzymes such as quinone reductase (QR) or glutathione S-transferase (GST) is considered a major mechanism of protection against initiation of carcingenesis. The induction of detoxification enzymes and glutathione were studied with Lonicerae Flos aqua-acupuncture solution (LFAS), Angelicae gigantis Radix aqua-acupuncture solution (AGRAS), and Gamdutang aqua-acupunture solution (GAS) in murine hepatoma cells grown in microtiter plate wells. LFAS, AGRAS and GAS were potent inducers of QR activity. LFAS was induced about 2.6-fold at concentration of $3{\times}$. AGRAS and GAS were also induced about 2.6-, 1.8-fold at concentration of $5{\times}$, respectively. In addition, GST activity was increased with LFAS, AGRAS, and GAS. GSH levels were increased about 2-fold with LFAS at concentration of $5{\times}$, 1.3-fold with AGRAS at concentration of $3{\times}$, and 1.2-fold with GAS at concentration of $5{\times}$. These results suggested that LFAS, AGRAS, and GAS may act as blocking agents against carcinogenesis by induction of phase II marker enzymes.

• Transactions of the Korean Society of Automotive Engineers
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• v.17 no.1
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• pp.43-49
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• 2009

A catalyzed diesel particulate filter (CDPF) causes the progressive increase in back pressure of an exhaust system due to the loading of soot particles. To minimize pressure drop which is generated by CDPF, the filter should be regenerated when it collects a certain quantity of soot. It is important to know characteristics of regeneration of CDPF with various of exhaust gas temperatures and compositions. The oxidation of HC in DOC leads to increase gas temperature of DOC downstream. The increased gas temperature by DOC has an positive effect on CDPF regeneration. This study presents characteristics of regeneration of CDPF with DOC according to various gas composition, such as HC and $O_2$ concentration. The test-rig is used to control each gas composition and temperature during regeneration of CDPF. Experimental results indicate that the increased concentration of $O_2$ regenerates DPF more actively. With increasing HC concentration, the gas temperature of CDPF upstream increased due to more oxidation of HC. But excessive supply of HC leads to decrease of $O_2$ concentration in the CDPF, which makes it hard to regenerate CDPF.

• Transactions of the Korean hydrogen and new energy society
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• v.24 no.1
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• pp.12-19
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• 2013

A gasification process with pre-combustion $CO_2$ capture process, which converts coal into environment-friendly synthetic gas, might be promising option for sustainable energy conversion. In the coal gasification for power generation, coal is converted into $H_2$, CO and $CO_2$. To reduce the cost of $CO_2$ capture and to maximize hydrogen production, the removal of CO and the additional production of hydrogen might be needed. In this study, a 2l/min water gas shift system for a coal gasifier has been studied. To control the concentration of major components such as $H_2$, CO, and $CO_2$, MFCs were used in experimental apparatus. The gas concentration in these experiments was equal with syngas concentration from dry coal gasifiers ($H_2$: 25-35, CO: 60-65, $CO_2$: 5-15 vol%). The operation conditions of the WGS system were $200-400^{\circ}C$, 1-10bar. Steam/Carbon ratios were between 2.0 and 5.0. The commercial catalysts were used in the high temperature shift reactor and the low temperature shift reactor. As steam/carbon ratio increased, the conversion (1-$CO_{out}/CO_{in}$) increased from 93% to 97% at the condition of CO: 65, $H_2$: 30, $CO_2$: 5%. However the conversion decreased with increasing of gas flow and temperature. The gas concentration from LTS was $H_2$: 54.7-60.0, $CO_2$: 38.8-44.9, CO: 0.3-1%.

• The Korean Journal of Ceramics
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• v.6 no.2
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• pp.150-154
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• 2000

Mobilities of electrons ($\mu_p$) and holes ($\mu_p$) in 2, 5, and 10 mol% $TiO_2$-doped yttria stabilized zirconia (TD-YSZ) have been estimated by a non-steady state gas permeation method using models proposed by Weppner and Maruyama. Values of $\mu_n$ and $\mu_p$ were found to be closed to those in non-doped YSZ reported earlier. The concentration of electrons and holes were calculated from $\mu_n$ and $\mu_p$ values and the partial conductivities of electrons and holes measured by a dc-polarization method. The concentration of electrons at unit oxygen partial pressure increased with increasing $TiO_2$concentration, while the hole concentration was almost independent of $TiO_2$concentration.

• Journal of Environmental Health Sciences
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• v.22 no.3
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• pp.72-80
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• 1996

This study was carried to investigate the biodegradability of phenol wastewater in the sluge blanket-packed bed reactor(SBPBR). The reactor consisted of two regions. The lower region was a sludge blanket of 0.5 m height and the upper region was a packed-bed. The phenol and COD concentration of the effluent, the gas production and the composition of gas were measured to determine the performance of the anaerobic wastewater treatment system as the phenol concentration of the influent was increased from 600 to 1800 mg/l. Stable biodegradation of phenol wastewater could be achieved with the anaerobic treatment system from 600 to 1200 mg/l of the influent phenol concentration. But the SBPBR system was getting more serious at 1800 mg/l of influent phenol concentration. At the steady state of the influent phenol concentration of 600-1200 mg/l, the treatment performance showed the phenol removal efficiency of 94.5~96.3%, the COD removal efficiency of 93.3~96% and the gas production of 4.94~9.64 l/day.

• Journal of Advanced Marine Engineering and Technology
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• v.24 no.3
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• pp.70-78
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• 2000

The effects of recirculated exhaust gas on the characteristics of ;$NO_x$ and soot emissions under a wide range of engine load have been experimentally investigated by a water-cooled, four-cylinder, indirect injection, four cycle and marine diesel engine operating at two kinds of engine speeds. The purpose of the present study is to develop the EGR control system for reducing $NO_x$ and soot emissions simultaneously in diesel engines. The EGR system is used to reduce NOx emissions, and a novel diesel soot removal apparatus with a cylinder-type scrubber for the experiment system which has 6 water injectors(A water injector is made up 144 nozzles with 1.0mm in diameter) is specially designed and manufactured to reduce the soot contents in the recirculated exhaust gas to intake system of the engines. The intake oxygen concentration obtained by the intake air flow and the oxygen concentration in the recirculated exhaust gas, and the exhaust oxygen concentration measured in exhaust manifold are used to analyse and discuss the influences of EGR on NOx and soot emissions. The experiments are performed at the fixed fuel injection timing of $15.3^{\circ}$ BTDC regardless of experimental conditions. It is found that $NO_x$ emissions decrease and soot emissions increase owing to the drop of intake oxygen concentration and exhaust oxygen concentration as EGR rate rises. Also, one can conclude that it is sufficient for the scrubber EGR system with a novel diesel soot removal apparatus to reduce $NO_x$ emissions, but not to reduce soot emissions.

• Journal of Mechanical Science and Technology
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• v.16 no.6
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• pp.861-869
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• 2002

Radiative transfer by nongray gas mixtures with nonuniform concentration and temperature profiles is studied by using the statistical narrow-band model and the ray-tracing method with the sufficiently accurate T$\_$60/ quadrature set. Transmittances through the nonhomogeneous gas mixtures are calculated by using the Curtis-Godson approximation. Three different cases with different temperature and concentration profiles are considered profiles are considered to obtain benchmark solutions for the radiative transfer by nongray gas mixtures. The solutions obtained from this study are verified and found to be very well matched with the previous solutions for uniform gas mixtures. The results presented in this paper can be used as benchmark solutions in developing various solution methods for radiative transfer by nongray gas mixtures.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.26 no.6
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• pp.833-841
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• 2002

The present study examined the possibility of NOx reduction in the high temperature industrial furnaces, duct burner of gas turbine cogeneration and two-stage gas turbine combustor. The experimental study was carried out for the non-premixed flame of second stage combustor with the variations of oxygen concentration in the hot exhaust gas of first stage combustor. It also examined the flammability range, temperature and NOx, $CO_2$, $O_2$formation in the combustor with respect to oxygen concentration in which the fuel(natural gas) is supplying into the hot exhaust gas. The results show that the inner temperature of flame reaches 1,20$0^{\circ}C$ at EGR $O_2$23% and that 15ppm of NOx at EGR $O_2$15.5% increases up to 60ppm at EGR $O_2$23%. It is believed that Fenimore＇s prompt NOx mechanism is more influential on the NOx formation than Zeldovich＇s thermal NOx mechanism does.

• Journal of Korean Society for Atmospheric Environment
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• v.21 no.3
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• pp.285-293
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• 2005

This study was aimed at estimation of gas-particle partitioning of polychlorinated biphenyls (PCBs) in ambient air. The samples were collected at urban site in Japan from March 2002 to January 2003. The concentration of total PCBs (from 4 CB to 10 CB) and TEQ (Toxic equivalent) ranged from 62 to $247\;pg/m^3$ and from 2 to $14\;fgTEQ/m^3 $, respectively. The average contribution $(\%)$ of gas phase to total PCBs concentration was above $80\%$, which suggests that in the atmosphere PCBs predominantly existed in the gas phase. The weak correlations between total PCBs concentration and temperature was found. However this result was due to a typhoon during summer and raining during sampling period. The gas-particle partition coefficient (Kp) was obtained as a function of temperature. The partition ratio of gaseous and particulate phase PCBs can be estimated for an arbitrary temperature. The plot of gas/particle partition coefficient (log Kp) vs. sub-cooled liquid vapor pressure $(log\;P_L)$ had reasonable correlations for individual samples but the slope varied among the samples (coefficients of determination for log Kp versus log $P_L$ plot were> 0.76 $(p<0.0001)$, except for 3 samples). As a result, the variations in the slope among the sampling period may be due to change of temperature, raining during sampling period and wind in this study.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.29 no.11
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• pp.41-46
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• 2015

This study was conducted to discover a substitute of $SF_6$ gas. $SF_6$ gas is widely used across the industries. Thanks to superior electrical properties, in particular, it has been commonly used in electrical industry. However, there have been a lot of studies on its serious effect on global warming. As a substitute of this synthetic gas, a mixture of dry air and $N_2/O_2$ was chosen in this study. In case of $N_2/O_2$, dielectric strength differs depending on the mixing ratio. This study examined dielectric breakdown and flashover after adjusting oxygen percentage in the dry air. This test was conducted in a quasi-uniform electric field depending on pressure, oxygen concentration and gas mixtures. The test results found that dielectric voltage and flashover voltage were the highest at a certain oxygen concentration. It is the results of this photoionization and electron attachment of oxygen.