• 한국태양에너지학회:학술대회논문집
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• 한국태양에너지학회 2012년도 춘계학술발표대회 논문집
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• pp.260-266
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• 2012

Syngas and hydrogen from the $CeO_2/ZrO_2$ coated foam devices were investigated under simulated solar radiation. The $CeO_2/ZrO_2$ coated SiC, Ni and Cu foam device were prepared using drop-coating method. Syngas production step was performed at $900^{\circ}C$, and hydrogen production process was performed for ten repeated cycles to compare the CeO2 conversion in syngas production step, $H_2$ yield in hydrogen production step and cycle reproducibility. The produced syngas had the $H_2$/CO ratio of 2, which was suitable for methanol synthesis or Fischer-Tropsch synthesis process. In addition, syngas and hydrogen production process is one of the promising chemical pathway for storage and transportation of solar heat by converting solar energy to chemical energy. After ten cycles of redox reaction, the $CeO_2/ZrO_2$ was analyzed using XRD pattern and SEM image in order to characterize the physical and chemical change of metal oxide at the high temperature.

• 한국태양에너지학회 논문집
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• 제34권6호
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• pp.11-18
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• 2014

Two-step water splitting thermochemical cycle with $CeO_2$ foam device was investigated by using a solar simulator composed of 2.5 kW Xe-Arc lamp and mirror reflector. The hydrogen production of $CeO_2$ foam device depending on reaction temperature of Thermal-Reduction step and Water-Decomposition step was analyzed, and the hydrogen production of $CeO_2$ and $NiFe_2O_4/ZrO_2$ foam devices was compared. As a result, the amount of reduced $CeO_2$ considerably varies according to the reaction temperature of Thermal-Reduction step. and hydrogen production was not much when the amount of reduced $CeO_2$ decreased even if the reaction temperature of Water-Decomposition step was high. Therefore, it is very important to keep the reaction temperature of Thermal-Reduction step high in two-step thermochemical cycle with $CeO_2$.

• 한국해양학회지:바다
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• 제23권1호
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• pp.49-62
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• 2018

순일차생산량과 종속 영양 생물의 호흡량의 차이로 정의되는 순군집생산량(net community production; NCP)은 해양 생물펌프의 척도로 활용되고 있다. 이 논문에서 소개하는 $O_2/Ar$ 관측에 기반한 NCP 추정법($O_2/Ar-NCP$)은 연구선의 이동 중에도 1분 미만의 고빈도로 $O_2/Ar$를 연속적으로 측정할 수 있어, 신생산량 혹은 방출생산량 등 전통적인 생물펌프 척도가 갖는 시간 혹은 공간 해상도의 제한을 혁신적으로 개선한 것이다. 논문에서는 $O_2/Ar-NCP$ 방법의 이론적 배경과 실험 장치의 구성에 대해 설명하였다. 또한 기존 생물펌프 척도와 $O_2/Ar-NCP$의 비교, 대양의 해역별 NCP 분포, 현장 관측 결과와 기계학습을 결합한 전 대양 NCP의 추정, 식물 플랑크톤 군집 구조와 NCP 연관성 등에 관한 주요 연구 사례들을 소개하였다.

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2000년도 추계학술발표대회 및 bio-venture fair
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• pp.171-174
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• 2000

본 연구는 용존산소의 양에 따른 MnP의 생산양상을 체계적으로 연구하였으며, 과량의 산소 공급 시 MnP 생산이 저해될 수 있음을 산소공급에 따른 과량의 $H_2O_2$생산 측면에서 설명하고 있다. 또한 보다 높은 MnP 생산을 위한 산소공급방법을 제시하고자 하였다.

• 한국태양에너지학회 논문집
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• 제33권2호
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• pp.93-100
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• 2013

Two-step thermochemical cycle using ferrite-oxide($Fe_2O_4$) device was investigated. The $H_2O$(g) was converted into $H_2$ in the first experiment which was performed using a dish type solar thermal system. However the experiment was lasted only for 2 cycles because the metal oxide device was sintered and broken down. Another problem was that the reaction was taken place mainly on a side of the metal oxide device. The m-$ZrO_2$, which was widely known as a material preventing sintering, was applied on the metal oxide device. The ferrite loading rate and the thickness of the metal oxide device were increased from 10.67wt% to 20wt% and from 10mm to 15mm, respectively. The chemical reactor having two inlets was designed in order to supply the reactants uniformly to the metal oxide device. The second-experiment was lasted for 5 cycles, which was for 6 hours. The total amount of the $H_2$ production was 861.30ml. And cerium oxide($CeO_2$) device was used for increasing $H_2$ production rate. $CeO_2$ device had low thermal resistance, however, more $H_2$ production rate than $Fe_2O_4$ device.

• 한국수소및신에너지학회논문집
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• 제22권2호
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• pp.206-212
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• 2011

The effect of process parameters on $H_2$ production from water vapor excited by HF ICP has been qualitatively examined for the first time. With the increase of ICP power, characteristics of $H_2$ production from $H_2O$ dissociation in plasma was divided into 3 regions according to both reaction mechanism and energy efficiency. At the edge of region (II) in the range of middle ICP power, energy effective hydrogen production from $H_2O$ plasma can be achieved. Furthermore, within the region (II) power condition, heating of substrate up to $500^{\circ}C$ shows additional increase of 70~80% in $H_2$ production compared to $H_2O$ plasma without substrate heating. This study have shown that combination of optimal plasma power (region II) and wall heating (around $500^{\circ}C$) is one of effective ways for $H_2$ production from $H_2O$.

• Bulletin of the Korean Chemical Society
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• 제30권2호
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• pp.302-308
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• 2009

This study investigated the production of hydrogen over Ga (1.0, 2.0, and 5.0 mol%)-$TiO_2$ photocatalysts prepared by a solvothermal method. The absorption band was slightly blue-shifted upon the incorporation of the gallium ions, but the intensity of the photoluminescence (PL) curves of Ga-incorporated $TiO_2$s was distinguishably smaller, with the smallest case being the 2.0 mol% Ga-$TiO_2$, which was related to the recombination between the excited electrons and holes. $H_2$ evolution from photo splitting of water over Ga-incorporated $TiO_2$ in the liquid system was enhanced, compared to that over pure $TiO_2$; particularly, the production of 5.6 mL of $H_2$ gas after 8 h when 1.5 g of the 2.0 mol% Ga-incorporated $TiO_2$ was used.

• Journal of Microbiology and Biotechnology
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• 제28권12호
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• pp.1982-1991
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• 2018

Ethanol accumulation inhibited the growth of Saccharomyces cerevisiae during wine fermentation. Autophagy and the release of reactive oxygen species (ROS) were also induced under ethanol stress. However, the relation between autophagy and ethanol stress was still unclear. In this study, expression of the autophagy genes ATG1 and ATG8 and the production of ROS under ethanol treatment in yeast were measured. The results showed that ethanol stress very significantly induced expression of the ATG1 and ATG8 genes and the production of hydrogen peroxide ($H_2O_2$) and superoxide anion (${O_2}^{{\cdot}_-}$). Moreover, the atg1 and atg8 mutants aggregated more $H_2O_2$ and ${O_2}^{{\cdot}_-}$ than the wild-type yeast. In addition, inhibitors of the ROS scavenging enzyme induced expression of the ATG1 and ATG8 genes by increasing the levels of $H_2O_2$ and ${O_2}^{{\cdot}_-}$. In contrast, glutathione (GSH) and N-acetylcystine (NAC) decreased ATG1 and ATG8 expression by reducing $H_2O_2$ and ${O_2}^{{\cdot}_-}$ production. Rapamycin and 3-methyladenine also caused an obvious change in autophagy levels and simultaneously altered the release of $H_2O_2$ and ${O_2}^{{\cdot}_-}$. Finally, inhibitors of the mitochondrial electron transport chain (mtETC) increased the production of $H_2O_2$ and ${O_2}^{{\cdot}_-}$ and also promoted expression levels of the ATG1 and ATG8 genes. In conclusion, ethanol stress induced autophagy which was regulated by $H_2O_2$ and ${O_2}^{{\cdot}_-}$ derived from mtETC, and in turn, the autophagy contributed to the elimination $H_2O_2$ and ${O_2}^{{\cdot}_-}$.

• 한국태양에너지학회 논문집
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• 제37권2호
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• pp.13-22
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• 2017

Two-step water splitting thermochemical cycle with $CeO_2/ZrO_2$ foam device was investigated by using a solar simulator composed of 2.5 kW Xe-Arc lamp and mirror reflector. The hydrogen production of $CeO_2/ZrO_2$ foam device depending on heat recovery of Thermal-Reduction step and Water-Decomposition step was analyzed, and the hydrogen production of $CeO_2/ZrO_2$ and $NiFe_2O_4/ZrO_2$ foam devices was compared. Resultantly, the quantity of hydrogen generation increased by 52.02% when the carrier gas of Thermal-Reduction step is preheated to $200^{\circ}C$ and, when the $N_2/steam$ is preheated to $200^{\circ}C$ in the Water-Decomposition step, the quantity of hydrogen generation increased by 35.85%. Therefore, it is important to retrieve the heat from the highly heated gases discharged from each of the reaction spaces in order to increase the reaction temperature of each of the stages and thereby increasing the quantity of hydrogen generated through this.

• Bulletin of the Korean Chemical Society
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• 제33권7호
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• pp.2133-2139
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• 2012

A new system using $TiO_2$ (nano-sized, band-gap 3.14 eV)-impregnated spherical ZnS (micro-sized, band-gap 2.73 eV) nano/micro-composites (Ti 0.001, 0.005, 0.01, and 0.05 mol %/ZnS) was developed to enhance the production of hydrogen from methanol/water splitting. The ZnS particles in a spherical morphology with a diameter of about 2-4 mm which can absorb around 455 nm were prepared by hydrothermal method. This material was used as a photocatalyst with loading by nano-sized $TiO_2$ (20-30 nm) for hydrogen production. The evolution of $H_2$ from methanol/water (1:1) photo splitting over the $TiO_2$/ZnS composite in the liquid system was enhanced, compared with that over pure $TiO_2$ and ZnS. In particular, 1.2 mmol of $H_2$ gas was produced after 12 h when 0.005 mol % $TiO_2$/ZnS nano/micro-composite was used. On the basis of cyclic voltammeter (CV) and UV-visible spectrums results, the high photoactivity was attributed to the larger band gap and the lower LUMO in the $TiO_2$/ZnS composite, due to the decreased recombination between the excited electrons and holes.