• 공업화학
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• 제30권6호
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• pp.719-725
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• 2019

본 실험에서는 활성탄소섬유에 산소플라즈마 처리를 실시하여 산소작용기 도입 함량에 따른 유독성 화학작용제의 모사 가스인 dimethyl methylphosphonate (DMMP) 감응특성에 대하여 고찰하였다. 산소플라즈마 처리 유량이 증가할수록 활성탄소섬유 표면에 산소가 6.90%에서 최대 36.6%까지 도입되어 DMMP 가스 감응특성에 영향을 미치는 -OH가 증가하였다. 그러나 유량이 증가할수록 산소플라즈마 처리 시 발생한 산소 활성종으로 인하여 활성탄소섬유 표면에 식각이 발생하여 비표면적은 감소하는 경향을 보였다. DMMP 가스센서의 저항변화율은 산소플라즈마 처리 유량이 증가함에 따라 4.2%에서 최대 25.1%까지 증가하였다. 이는 산소플라즈마 처리로 인하여 활성탄소섬유에 발달된 -OH와 DMMP 가스의 수소결합으로 인한 것이라 여겨진다. 따라서 산소플라즈마 처리는 상온에서 유독성화학작용제 가스를 감지하기 위한 중요한 표면처리 방법 중 하나라고 판단된다.

• Journal of Ginseng Research
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• 제41권2호
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• pp.169-179
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• 2017

Background: Ginsenosides are the main pharmacological components of Panax ginseng root, which are thought to be primarily responsible for the suppressing effect on oxidative stress. Methods: 2,2-diphenyl-1-picrylhydrazyl radical scavenging activity and oxygen radical absorption capacity were applied to evaluate the antioxidant activities of the ginsenosides. Human embryonic kidney 293 (HEK-293) cells were incubated with ginsenosides extracted by pulsed electric field (PEF) and solvent cold soak extraction (SCSE) for 24 h and then the injury was induced by $40{\mu}M$ $H_2O_2$. The cell viability and surface morphology of HEK-293 cells were studied using MTS assay and scanning electron microscopy, respectively. Dichloro-dihydro-fluorescein diacetate fluorescent probe assay was used to measure the level of intracellular reactive oxygen species. The intracellular antioxidant activities of ginsenosides were evaluated by cellular antioxidant activity assay in HepG2 cells. Results: The PEF extracts displayed the higher 2,2-diphenyl-1-picrylhydrazyl radical scavenging activity and stronger oxygen radical absorption capacity (with an oxygen radical absorption capacity value of $14.48{\pm}4.04{\mu}M\;TE\;per\;{\mu}g/mL$). The HEK-293 cell model also suggested that the protective effect of PEF extracts was dose-dependently greater than SCSE extracts. Dichloro-dihydro-fluorescein diacetate assay further proved that PEF extracts are more active (8% higher than SCSE extracts) in reducing intracellular reactive oxygen species accumulation. In addition, scanning electron microscopy images showed that the HEK-293 cells, which were treated with PEF extracts, maintained more intact surface morphology. Cellular antioxidant activity values indicated that ginsenosides extracted by PEF had stronger cellular antioxidant activity than SCSE ginsenosides extracts. Conclusion: The present study demonstrated the antioxidative effect of ginsenosides extracted by PEF in vitro. Furthermore, rather than SCSE, PEF may be more useful as an alternative extraction technique for the extraction of ginsenosides with enhanced antioxidant activity.

• Journal of Mechanical Science and Technology
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• 제17권9호
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• pp.1358-1370
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• 2003

The effects of anode, cathode, and cooling channels for a Proton Exchange Membrane Fuel Cell (PEMFC) on flow fields have been investigated numerically. Continuous open-faced fluid flow channels formed in the surface of the bipolar plates traverse the central area of the plate surface in a plurality of passes such as a serpentine manner. The pressure distributions and velocity profiles of the hydrogen, air and water channels on bipolar plates of the PEMFC are analyzed using a two-dimensional simulation. The conservation equations of mass, momentum, and energy in the three-dimensional flow solver are modified to include electro-chemical characteristics of the fuel cell. In our three-dimensional numerical simulations, the operation of electro-chemical in Membrane Electrolyte Assembly (MEA) is assumed to be steady-state, involving multi-species. Supplied gases are consumed by chemical reaction. The distributions of oxygen and hydrogen concentration with constant humidity are calculated. The concentration of hydrogen is the highest at the center region of the active area, while the concentration of oxygen is the highest at the inlet region. The flow and thermal profiles are evaluated to determine the flow patterns of gas supplied and cooling plates for an optimal fuel cell stack design.

• The Plant Pathology Journal
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• 제21권3호
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• pp.283-287
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• 2005

Since the discovery of generation of $O_2^-$ in plant, many evidence for the oxidative burst (OXB) has been accumulated in various combinations of plant and pathogen or elicitor systems. $O_2^-$ generating system responsible for the OXB was coupled with oxidation of reduced nicotinamide adenine dinucleotide phosphate (NADPH) in microsomal fraction isolated from sliced aged potato tuber slices which were treated by hyphal wall components elicitor from Phytophthora infestans (HWC). We developed new assay method for quantitative measurement of oxygen radical $O_2^-$ by using electron spin resonance (ESR) analysis during elicitor­induced OXB on the surface of plant tissues. The ESR analysis using an $O_2^-$ trapper, Tiron (1,2-dihydroxy-3,5­benzenedisulfonic acid), provided a convenient assay for detecting only $O_2^-$ during elicitor-induced OXB producing various active oxygen species (AOS) on plant tissue surface. Tiron was oxidized to Tiron semiquinon radical by $O_2^-$. Quantity of the radical signal was measured by specific spectra on ESR spectroscopy. The level of $O_2^-$ was high in from surface of potato tuber tissue treated with hyphal cell wall elicitor (HWC) from Phytophthora infestans. There was no secondary OXB induction by $H_2O_2$ treatment in plant.

• 한국응용약물학회:학술대회논문집
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• 한국응용약물학회 2000년도 춘계학술대회
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• pp.6-7
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• 2000

Recently, free radicals such as active oxygen species, nitric oxide, etc are believed to be one of the key substances in physiological and pathological, toxicological phenomena, and oxidative damages, and all organism have defencing system against such as free radicals. Formation and extinction of free radicals may be regulated through bio-redox system, in which various enzymes and compounds should be involved in very complicated manner. Thus, direct and non-invasive measurement of in vivo free radical reactions with living animals must be essential to understand the role of free radicals in pathophysiological phenomena. Electron spin resonance spectroscopy (ESR) is very selective and sensitive technique to detect free radicals, but a conventional ESR spectrometer has large detect in application to living animals, since high frequent microwave is absorbed with water, resulting in generation of high fever in living body. In order to estimate in vivo free radical reactions in living whole animals, we develop in vivo ESR-CT technique using nitroxide radicals as spin probes. Nitroxide radicals and their reduced forms, hydroxylamines, are known to interact with various redox systems. We found that! ! the signal decay due to reduction of nitroxyl radicals is influenced by aging, inspired oxygen concentration, ischemia-referfusion injury, radiation, etc. In the present paper, I will introduce in vivo ESR technique and my laboratory recent results concerning non-invasive evaluation of free radical reactions in living mice.

• 약학회지
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• 제40권5호
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• pp.563-573
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• 1996

The system most likely responsible for the accelerated metabolism of alcohol with chronic ingestion or at high blood ethanol levels, is the microsomal ethanol-oxidizing system(M EOS). While the increase in the MEOS with chronic ethanol ingestion is thought to be adaptive, it may also have serious adverse effects on the liver. The rates of the NADPH-dependent oxygen consumption by the liver microsomes from the prolonged ethanol fed rats were 2 times higher than the rates from the non-treated rats. With the alcohol ingestion, the total SH and nonprotein SH contents showed the significant decrease and at the same time, MDA in liver and GOT and GPT levels in blood showed the significant increase, which suggests the occurrence of liver damage due to the oxidative stress caused by chronic alcohol consumption. The mitochondrial aldehyde dehydrogenase(ALDH) activity was decreased by chronic ethanol ingestion, whereas the alcohol dehydrogenase activity and the cytosolic ALDH activity were not altered. These results suggest that the induction of cytochrome P450 by the chronic alcohol ingestion increases the oxidative stress which seems to result in the altered the physiological states of the liver including the ALDH activity, which may in turn to lead to the liver disease.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 추계학술대회 논문집 Vol.16
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• pp.152-155
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• 2003

Ashing of photoresist was investigated in dielectric barrier discharges in atmospheric pressure by changing applied voltage, frequency, flow rate. we analyzed the plasma by Optical Emission Spectroscopy(OES) to monitor the variation of active oxygen species. Another new peaks of oxygen radical is observed by addition of argon gas. This may explain the increase in ashing rate with argon addition. With the results of Optical Emission Spectroscopy(OES), we can find the optimized ashing conditions. MIS capacitor for monitoring charging damage by the plasma was also studied. The results suggest the dielectric barrier discharges(DBD) can be an efficient, alternative Plasma source for general surface processing.

• 공업화학
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• 제30권2호
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• pp.160-166
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• 2019

본 연구에서는 새집증후군 유발 가스인 초산 가스에 대한 활성탄소섬유의 흡착 성능을 향상시키기 위하여, 산소플라즈마 처리를 통해 활성탄소섬유에 산소작용기를 도입하였다. 산소플라즈마 처리 시 주입되는 산소 가스의 유량이 증가할수록 산소플라즈마 활성종이 더 많이 생성되었다. 이로 인해 물리적 및 화학적인 식각이 더 많이 발생하여 활성탄소섬유의 비표면적이 감소하였다. 특히, 60 sccm의 산소 가스 유량이 주입된 시료(A-O60)의 비표면적의 경우 미처리 시료와 비교하여 약 6.95% 감소된 $1.198m^2/g$까지 감소하였다. 반면, 산소플라즈마 처리 시 주입되는 산소 가스의 유량이 증가할수록 활성탄소섬유 표면에 도입되는 산소 함량이 증가하였으며, 최대 35.87%까지 도입되었음을 확인하였다. 또한, 산소플라즈마 처리된 활성탄소섬유의 초산 가스 흡착 성능은 미처리 활성탄소섬유 대비 최대 43% 향상되었다. 이것은 산소플라즈마 처리에 의해 도입되는 O=C-O와 같은 산소작용기와 초산 분자 사이의 쌍극자 모멘트에 의한 수소결합 형성에 기인한다.

• 청정기술
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• 제29권4호
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• pp.321-326
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• 2023

최근 탄소중립과 관련하여 연소 시 이산화탄소 배출이 없어 청정한 수소에너지에 대한 관심이 증가하고 있다. 이에 따라 수소 생산에 관련된 연구가 계속되고 있으며 본 연구에서는 폐기물을 처리함과 동시에 고순도 수소를 생산하기 위해 폐기물 유래 합성가스를 수성가스전이반응에 적용하였다. 마그네슘을 세륨과 함께 지지체로 사용하여 고온수성가스전이(HT-WGS)반응에서 촉매의 활성을 향상시키고자 하였다. HT-WGS 반응의 활성물질로 구리를 사용해 Cu-CeO₂-MgO 촉매를 제조하였으며, 제조방법에 따른 촉매활성 연구를 진행하였다. HT-WGS 반응 결과 함침법으로 제조된 Cu-CeO₂-MgO 촉매가 가장 높은 활성을 보였으며, 이는 가장 높은 산소 저장능과 많은 활성 Cu 종을 가지는 특성에 기인한 결과이다.

• 한국해양학회지
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• 제30권4호
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• pp.250-261
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• 1995

본 연구는 남해안 가막만의 저서다모류군집의 분포 특성을 조사하기 위하여 1993 년 여름에 수행되었다. 다모류는 전체 저서동물중 개체수에 있어서 74.5%를 점하는 가 장 우점하는 동물군으로서 총 84종이 채집되었으며, 평균 서식밀도는 253 indiv.m/SUP -2/ 이었다. 대체로 가막만의 내해역과 의해역을 연결하는 북동쪽 수로와 남쪽 입구역 부근에서 출현 종수가 많았고 서식밀도가 높았다. 우점하는 다모류는 Tharyxsp sp.(31.9%), Lumbrineris longifolia (27.5%), Chone sp.(4.5%), Glycera chirori(4.2%) 등이었다. 조화분석 결과 가막만은 저서다모류의 종수와 서식밀도에 따 라 4개의 구역으로 나뉘어졌다. 만의 양쪽 입구에 해당되는 북동수로와 암쪽입구역은 Tharyx-Chone 군집이 형성되어 있으며, 가막만에서 저서다모류상이 가장 풍부한 해역 이었다. 반면 북서내만역과 백야도 인근해역은 저서동물의 서식이 거의 불가능할 정도 로 다모류가 빈약한 해역이다. 그리고 만의 중앙에 위치하는 해역은 Praxillella-Terebellides 군집이, 중앙의 구릉역에는 Glycera군집이 형성되어 있으 며, 종수 및 서식밀도에 있어서 만의 입구역과 북서내만역의 점이역에 해당되는 해역 이라 할 수 있다. 즉 가막만은 양 입구역만 해수교안이 불량하고, 과다한 퇴적물내 유 기물 함량, 저층수의 낮은 용존산소 농도로 인하여 빈약한 다모류 군집이 형성되어 있 다.