• 한국정보통신학회논문지
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• 제6권7호
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• pp.1095-1099
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• 2002

본 논문은 1064 m의 Q-스위칭 Nd:YAG로 펌핑된 단일통과 라만레이저에서 nano-초의 스토크스 펄스발생에 관한 연구이며, 라만 매질로는 GeO2로 도핑된 grad index형 다중모드 파이버 220 m를 사용하였다. 실험 결과에서 펌핑 에너지의 변화에 따라 1.5∼2.7 nano 초의 펄스폭을 갖는 스토크스 펄스 트래인 싱분이 효율적으로 발생함을 알 수 있었다.

• 한국약용작물학회지
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• 제17권1호
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• pp.68-74
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• 2009

Vitis amurensis (VA; Vitaceae) has long been used in oriental herbal medicine. It has been reported that roots and seeds of VA have anti-inflammatory and antioxidant effects. In the present study, the protective effect of ethanol extract from stems and leaves of VA on hydrogen peroxide (${H_2}{O_2}$) (100 ${\mu}M$)-induced neuronal cell damage was examined in primary cultured rat cortical neurons. VA (10-100 ${\mu}g$/ml) concentration-dependently inhibited ${H_2}{O_2}$-induced apoptotic neuronal cell death measured by 3-[4,5-Dimethylthiazol-2-yl]-2,5-diphenyl-tetrazolium bromide (MTT) assay and Hoechst 33342 staining. VA inhibited ${H_2}{O_2}$-induced elevation of intracellular $Ca^{2+}$ concentration (${[Ca^{2+}]}_i$) and generation of reactive oxygen species (ROS), which were measured by fluorescent dyes. Pretreatment of VA also prevented glutamate release into medium induced by 100 ${\mu}M$ ${H_2}{O_2}$, which was measured by HPLC. These results suggest that VA showed a neuroprotective effect on ${H_2}{O_2}$-induced neuronal cell death by interfering with ${H_2}{O_2}$-induced elevation of ${[Ca^{2+}]}_i$, glutamate release, and ROS generation. This has a significant meaning of finding a new pharmacological activity of stems and leaves of VA in the CNS.

• 마이크로전자및패키징학회지
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• 제15권1호
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• pp.1-6
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• 2008

칼슘 코발트 층상 산화물계에서 $Ca_3Co_2O_6$와 $Ca_3Co_4O_9$를 기본으로 하여 열전 특성 향상을 위해 Ca 위치를 Bi, Sr, La, K로 부분 치환하고, Co위치를 Mn, Fe, Ni, Cu, Zn로 치환한 다결정 산화물을 제조하여 $300{\sim}1000K$ 까지의 열전 특성을 분석하였다. Bi가 치환된 $Ca_3Co_4O_9$계의 $Ca_{2.7}Bi_{0.3}Co_4O_9$는 전기전도도 $85.4({\Omega}cm)^{-1}, Seebeck계수 $176.2{\mu}V/K$그리고 파워팩터 $265.2{\mu}W/K^m$로 가장 높은 열전 물성치가 관찰되었다. 열전 모듈 제조를 위해서 각각의 열전반도체의 성능지수Z($10^{-4}/K$)가 0.87, 0.41의 값인 p형 열전 소재로 $Ca_{2.7}Bi_{0.3}Co_4O_9$를, n형 열전 소재로($Zn_{0.98}Al_{0.02}$)O를 선택하여 열전쌍을 제조하였다. 제조된 2쌍의 기본 열전쌍은 120K의 온도차에서 약 30mV정도의 기전력이 나타났다.

• 대한환경공학회지
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• 제27권12호
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• pp.1263-1269
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• 2005

용액 상에서 페놀류에 대해 95%의 분해특성을 지니는 동식물세포유래의 효소(horseradish peroxidase, HRP, EC 1.11.1.7)를 다공성 탄소 전극에 고정화시키고 이를 전기화학 반응기에 도입하여 전극반응에 의해 연속적으로 발생되는 과산화수소를 이용하여 페놀의 분해를 수행하였다. FT-IR 분석을 통해 다공성탄소전극 표면에 HRP의 아민기와 펩티드 결합을 위한 카르복실기가 생성되었음을 확인하였고 가교제(coupling agent)로 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride(EDC)를 이용하여 공유결합으로 고정화시켰다. 또한 HRP를 활성화 시켜 페놀을 처리하기 위해 전해질로 사용된 인산염 완충용액의 농도($10{\sim}200$ mM)와 pH($5.0{\sim}8.0$), 외부 산소 주입량($10{\sim}50$ mL/min)및 potentiostat/galvanosta에 의한 외부 공급전압($-0.2{\sim}-0.8$ volt, vs. Ag/AgCl)의 조건을 달리하며 RVC 전극 표면에서 발생되는 과산화수소 농도 및 전류효율을 고려하여 최적 자체 발생조건을 결정하였다. HRP가 고정화된 RVC 전극은 초기 고정화된 HRP 활성에 대해 4주 동안 89%의 상대적 효소 활성도(relatively enzymatic activity)를 지니는 안정한 전극임을 확인하였으며 실험실 스케일의 연속식 전기화학 반응기에 도입되어 최적 과산화수소의 발생조건에서 86%의 분해 효율을 보였다.

• 대한한의학회지
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• 제30권1호
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• pp.51-63
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• 2009

Objectives: Peroxynitrite ($ONOO^-$), superoxide anion radical (${\cdot}{O_2}^-$ and nitric oxide (NO) are cytotoxic because they can oxidize several cellular components such as proteins, lipids and DNA. They have been implicated in the aging processes, and age-related diseases such as Alzheimer's disease, rheumatoid arthritis, cancer, diabetes, obesity and atherosclerosis. The aim of this study was to investigate the $ONOO^-$, NO, ${\cdot}{O_2}^-$ scavenging and NF-${\kappa}B$ related anti-inflammatory activities of Sotosaja-hwan in ob/ob mice. Methods: Mice were grouped and treated for 5 weeks as follows. Both the normal lean (C57/BL6J black mice) and control obese (ob/ob mice) groups have received standard chow. The experimental groups were fed with a diet of chow supplemented with 30 and 90 mg Sotosaja-hwan per 1 kg of body weight for 14 days. For this study, the fluorescent probes, namely 2',7'-dichlorodihydrofluorescein diacetate (DCFDA), 4,5-diaminofluorescein (DAF-2) and dihydrorhodamine 123 (DHR 123) were used. Western blotting was performed using anti-phospho-$I{\kappa}B$-${\alpha}$, anti-IKK-${\alpha}$, anti-NF-${\kappa}B$ (p50, p65), anti-COX-2, anti-iNOS, anti-YCAM-1 and anti-MMP-9 antibodies, respectively. Results: Sotosaja-hwan inhibited the generation of $ONOO^-$, NO and ${\cdot}{O_2}^-$ in the lipopolysaccharide (LPS)-treated mouse kidney postmitochondrial fraction in vitro. The generation of $ONOO^-$, NO, ${\cdot}{O_2}^-$ and PGE2 were inhibited in the Sotosaja-hwan-administered ob/ob mice groups. The GSH/GSSG ratio was decreased in the ob/ob mice, whereas the ratio was improved in the Sotosaja-hwan-administered groups. Sotosaja-hwan inhibited the protein expression levels of phospho-$I{\kappa}B$-${\alpha}$, IKK-${\alpha}$, NF-${\kappa}B$ (p50, p65), COX-2, iNOS, YCAM-1 and MMP-9 genes. Conclusions: These results suggest that Sotosaja-hwan is an effective $ONOO^-$, ${\cdot}{O_2}^-$ and NO scavenger and has NF-kB related anti-inflammatory activity in ob/ob mice. Therefore, Sotosaja-hwan might be a potential therapeutic drug against the inflammation process and inflammation-related diseases.

• 한국항공우주학회지
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• 제43권4호
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• pp.296-303
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• 2015

무인기 운용 환경을 고려하여 다양한 조성의 $NaBH_4$ 용액을 사용해 수소발생시스템의 성능 평가를 수행하였다. 먼저, 자발가수분해와 30분의 수소발생실험을 수행하였다. 수소의 손실, 안정한 수소 발생, $NaBO_2$의 석출, 전환 효율과 무인기의 운용을 고려하여 $NaBH_4$ 용액의 조성을 1 wt% NaOH + 25 wt% $NaBH_4$+74wt% $H_2O$로 결정하였다. 200 W급 연료전지 시스템을 위해 장시간 수소발생실험도 수행되었다. 비록 $NaBO_2$의 석출로 인해서 수소 발생률이 감소하였지만, 200 W 연료전지를 위한 수소를 3시간동안 발생(전환 효율: 87.4%)시켰다. 600 Wh의 에너지를 갖는 200 W급 연료전지 시스템의 에너지 밀도는 263 Wh/kg이었다. 기존 배터리 무인기에 비해 약 1.5배 이상의 체공 시간을 달성할 수 있다.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2008년도 하계종합학술대회
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• pp.487-488
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• 2008

SiOC films containing alkyl groups have a low dielectric constant because of the interaction between the C-H hydrogen bonds and the oxygen of high electro-negative atom. The Si-$CH_3$ in a void is broken by the $O_2$, therefore the strength of CH bond in Si-O-O-$CH_3$ bond increases. The Si-O-O-$CH_3$ bond is broken by nucleophilic attack due to Si atom, again. The elongation of C-H bond causes the red shift, and the compression of C-H bond causes the blue shift. Among these chemical shifts, the blue shift from $1000\;cm^{-1}$ to $1250\;cm^{-1}$ was related with the formation of pores. If the oxygen is deficient condition, the methylradicals of the electron-rich substitution group terminate easily the Si-O-Si cross-link, and the pore is originated from the cross-link breakdown due to much methyl radicals of Si-$CH_3$. The dielectric constant of the films decreases due to pore generation.

• 한국재료학회지
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• 제29권1호
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• pp.16-22
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• 2019

Indirect oxidation using chlorine species oxidizing agents is often effective in wastewater treatment using an electrochemical oxidation process. When chlorine ions are contained in the wastewater, oxidizing agents of various chlorine species are produced during electrolysis. In a ballast water management system, it is also used to treat ballast water by electrolyzing seawater to produce a chlorine species oxidizer. However, ballast water in the brackish zone and some wastewater has a low chlorine ion concentration. Therefore, it is necessary to study the chlorine generation current efficiency at various chlorine concentration conditions. In this study, the chlorine generating current efficiency of a boron-doped diamond(BDD) electrode and insoluble electrodes are compared with various chloride ion concentrations. The results of this study show that the current efficiency of the BDD electrode is better than that of the insoluble electrodes. The chlorine generation current efficiency is better in the order of BDD, MMO(mixed metal oxide), $Ti/RuO_2$, and $Ti/IrO_2$ electrodes. In particular, when the concentration of sodium chloride is 10 g/L or less, the current efficiency of the BDD electrode is excellent.

• 한국전기전자재료학회논문지
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• 제24권5호
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• pp.427-431
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• 2011

Hybrid $SiO_2-TiO_2$ photoelectrode with different type of layers was investigated in dye-sensitized solar cells (DSSC). Use of a thin layer of nanocrystalline $TiO_2$ would imply reduction in the amount of dye coverage, however, lower amount of dye in the thin films would imply fewer electron generation upon illumination. So, thus, it becomes necessary to include a $SiO_2-TiO_2$ layer for increase light harvesting effect such that the lower photon conversion due to thin layer could be compensated. In this paper reports the use of transparent high surface area $TiO_2$ layer and an additional $SiO_2-TiO_2$ layer, thus ensuring adequate light harvesting in these devices. The best solar conversion efficiency 6.6% under AM 1.5 was attained with a multi-layer structure using $TiO_2$ layer/$SiO_2-TiO_2$ layer/$TiO_2$ layer for the light harvesting and this had resulted to about 44% increase in photocurrent density of dye-sensitized solar cells.

• 방사성폐기물학회지
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• 제19권2호
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• pp.271-278
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• 2021

In this study, a chlorination technique for recycling Li₂ZrO₃, a reaction product of ZrO₂-assisted rinsing process, was investigated to minimize the generation of secondary radioactive pyroprocessing waste. It was found that the reaction temperature was a key parameter that determined the reaction rate and maximum conversion ratio. In the temperature range of 400-600℃, an increase in the reaction temperature resulted in a profound increase in the reaction rate. Hence, according to the experimental results, a reaction temperature of at least 450℃ was proposed to ensure a Li₂ZrO₃ conversion ratio that exceeded 80% within 8 h of the reaction time. The activation energy was found to be 102 ± 2 kJ·mol^-1·K^-1 between 450 and 500℃. The formation of LiCl and ZrO₂ as reaction products was confirmed by X-ray diffraction analysis. The experimental results obtained at various total flow rates revealed that the overall reaction rate depends on the Cl₂ mass transfer rate in the experimental condition. The results of this study prove that the chlorination technique provides a solution to minimize the amount of radioactive waste generated during the ZrO₂-assisted rinsing process.