• Bulletin of the Korean Chemical Society
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• v.32 no.12
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• pp.4392-4396
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• 2011

Porous silicon with a complex network of nanopores is utilized for photoelectrochemical energy conversion. A novel electroless Pt deposition onto porous silicon is investigated in the context of photoelectrochemical hydrogen generation. The electroless Pt deposition is shown to improve the characteristics of the PS photoelectrode toward photoelectrochemical $H^+$ reduction, though excessive Pt deposition leads to decrease of photocurrent. Furthermore, it is found that a thin layer (< 10 ${\mu}m$) of porous silicon can serve as anti-reflection layer for the underlying Si substrate, improving photocurrent by reducing photon reflection at the Si/liquid interface. However, as the thickness of the porous silicon increases, the surface recombination on the dramatically increased interface area of the porous silicon begins to dominate, diminishing the photocurrent.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.31 no.10
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• pp.855-859
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• 2007

Hydrogen as an energy carrier in fuel cell offers perhaps the largest potential benefits of reduced emissions of pollutants and greenhouse gases. The generation of high-purity hydrogen from hydrocarbon fuels is essential for efficient operation of fuel cell. Reduction of carbon monoxide to an acceptable level of 10ppm involves high temperature and low temperature water gas shift (WGS), followed by selective oxidation of residual carbon monoxide. The WGS reactor was designed and tested in this study to produce hydrogen-rich gas with CO to less than 5000 ppm. In the water gas shift operation, gas emerges from the reformer is taken through a high temperature shift (HTS) catalyst to reduce the CO concentration to about $2{\sim}4%$ followed to about 5000 ppm via a low temperature shift (LTS) catalyst.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.717-724
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• 2008

Very High Temperature Gas Cooled Reactor (VHTR) has been selected as a high energy heat source for nuclear hydrogen generation, which can produce hydrogen from water or natural gas. A primary hot gas duct (HGD) as a coaxial double-tube type cross vessel is a key component connecting the reactor pressure vessel and the intermediate heat exchanger for the VHTR. In this study, structural sizing methodology for the primary HGD with a coaxial double-tube of the VHTR that produces heat at temperatures in the order of $950^{\circ}C$ was suggested and a structural pre-sizing of it was carried out as an example.

• Toxicological Research
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• v.17 no.4
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• pp.249-253
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• 2001

Fumonisin B1, a mycotoxin, is thought to induce esophageal cancer in humans and apoptosis in animal cells by inhibiting ceramide synthase. Dumonisin Bl may also generate reactive oxygen species directly or indirectly, leading to DNA damage and lipid peroxidation. In this study, a DNA fragmentation assay, dichlorofluorescein (DCF) analysis, and single cell gel electrophoresis (SCGE) were used to investigate the involvement of cellular free radicals, specifically hydrogen peroxide, in the DNA damaging activity of fumonisin B1. From an in vitro DNA fragmentation assay, E. coli DNA, damage by fumonisin Bl was increased by the addition of superxide dismutase (SOD) and decreased by catalase. SCGE and DCF analysis in vivo showed that the nuclear DNA damage and intracellular free radicals in cultured rat hepatocytes treated with fumonisin B1 were increased with the concentration of fumonisin Bl . DNA damage and free radical generation were inhibited by the addition of catalase. Fumonisin Bl , in the presence of SOD, produces hydrogen peroxide causing oxidative DNA damage and protein malfunction, leading to genotoxicity and cytotoxicity of the toxin.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.24 no.9
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• pp.136-141
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• 2010

In this paper, after the third electrode type oxidant generator which could format non-uniform electric field in water had been manufactured and installed, by direct electrolysis, the effects of the hydrogen potential and oxidation reduction potential characteristics attendant upon electric field change on a higher concentration oxidant generation characteristics were investigated. Consequently, as the third electrode was installed in the middle of two slit electrodes and the polarity of applied power was changed, it was observed that the third electrode system with the positive electrode can generate a higher concentration oxidant, hydrogen potential and oxidation reduction potential as compared with that of the negative electrode. It is because the positive electrode was bombarded mostly energetic electrons and the negative electrode was bombarded mainly by less energetic positive ions.

• Journal of the Korean Society for Precision Engineering
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• v.24 no.6
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• pp.105-112
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• 2007

Tungsten wire micro electrochemical machining (W-wire micro ECM) with ultra-short pulses enables precise micro machining of metal. In wire micro ECM, platinum wire has been used because it is electrochemically stable. However, the micro metal wire with low strength is easily deformed by hydrogen bubbles which are generated during the machining. The wire deformation decreases the machining accuracy. To reduce the influence of hydrogen bubbles, in this paper, the use of tungsten wire was investigated. To improve machining accuracy, suitable pulse conditions which affect generation of bubbles were also investigated. The tungsten wire micro ECM can be applied to the fabrication of various shapes. Using this method, various micro-parts and shapes were fabricated.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.07a
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• pp.29-30
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• 2005

Experimental results are presented for the degradation of 3 nm-thick gate oxide ($SiO_2$) under both Negative-bias Temperature Instability(NBTI) and Hot-carrier-induced(HCI) stresses using P and NMOSFETs that are annealed with hydrogen or deuterium gas at high-pressure (1~5 atm.). Statistical parameter variations depend on the stress conditions. We suggest that deuterium bonds in $SiO_2$ film is effective in suppressing the generation of traps related to the energetic hot electrons.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.03a
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• pp.579-582
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• 2008

PEM Fuel cell system was designed and constructed to use as a power source of unmanned aerial vehicles(UAV) in the present study. Sodium borohydride was selected as a hydrogen source and was decomposed by catalytic hydrolysis reaction. Fuel cell system consists of a fuel cell stack, a hydrogen generation system(HGS), and power management system(PMS). HGS was composed of a catalytic reactor, micropump, fuel cartridge, and separator. Hybrid power system between lithium-polymer battery and fuel cell was developed. The fuel cell system was integrated and packaged into a blended wing-body UAV. Energy density of the total system was 1,000 $W{\cdot}hr/kg$ and high endurance more than 5 hours was accomplished in the ground tests.

• Journal of the Korean institute of surface engineering
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• v.56 no.6
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• pp.412-419
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• 2023

Anion exchange membrane electrolysis is considered a promising next-generation hydrogen production technology that can produce low-cost, clean hydrogen. However, anion exchange membrane electrolysis technology is in its early stages of development and requires intensive research on electrodes, which are a key component of the catalyst-system interface. In this study, we optimized the pressure conditions of the hot-pressing process to manufacture cobalt oxide electrodes for the development of a high uniformity and high adhesion electrode production process for the oxygen evolution reaction. As the pressure increased, the reduction of pores within the electrode and increased densification of catalytic particles led to the formation of a uniform electrode surface. The cobalt oxide electrode optimized for pressure conditions exhibited improved catalytic activity and durability. The optimized electrode was used as the anode in an AEMWE single cell, exhibiting a current density of 1.53 A cm^-2 at a cell voltage of 1.85 V. In a durability test conducted for 100 h at a constant current density of 500 mA cm^-2, it demonstrated excellent durability with a low degradation rate of 15.9 mV kh^-1, maintaining 99% of its initial performance.

• 유체기계공업학회:학술대회논문집
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• 2001.11a
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• pp.367-372
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• 2001

A fuel cell is an electrochemical energy conversion device tint converts hydrogen and oxygen into electricity and heat for hot water and heating room A fuel cell provides a DC voltage tint can be used to power motors, lights or any number if electrical appliances. There are several different types if fuel cells, each using a different chemistry. Some types if fuel cells show promise for use in DC (distributed generation) because fuel cell is very clean and efficient energy device. CETI (Clean Energy Technologies, Inc.) is developing PEMFC and DMFC for residential power generation, portable and battery. It is anticipated tint RPG is advantageous over current power generation by utility In terms if economics assuming the lifetime of major components is at least five years.