• Transactions of the Korean hydrogen and new energy society
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• v.5 no.1
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• pp.51-57
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• 1994

Compaction techniques of hydrogen storage alloy 'powders, to solve the problems due to disintegration during the cyclic hydriding and dehydriding, by using polytetrafluoroethylene (PTFE) and silicon sealant as a polymer binder were studied. Optimum conditions of compaction were as follows. Binder content, 10 % for PTFE and 5 % for silicon sealant ; particle size of alloy powders, $-25{\mu}m$ ; compacting pressure, $4ton/cm^2$. Compacts obtained were easily activated and had a good strength even after 30 cycles of hydriding and dehydriding. PTFE added compacts showed very good rate capability, however, in the silicon added compacts hydrogen absorption rate was somewhat slow because of higher elasticity and adhesiveness of the binder.

• Environmental Engineering Research
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• v.10 no.1
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• pp.7-14
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• 2005

The feasibility of hydrogen production with a raw seed sludge through direct acclimation of feedstock was investigated at acidogenic stage, and methane was harvested at followed methanogenic stage in an anaerobic two-stage process. Hydrogen content was higher than 57% at all tested organic loading rates (OLRs) and the yield of hydrogen ranged from 1.5 to 2.4 mol H2/mol hexose consumed and peaked at 6 gVSl-1day-1. Normal butyrate and acetate were main volatile fatty acids (VFAs), whereas the concentration of propionate was insignificant. The hydrogen-producing bacteria, Clostridium thermosaccharolyticum, was detected with strong intensity at all tested organic loading rates (OLRs) by denaturing gradient gel electrophoresis (DGGE) of the polymerase chain reaction (PCR) analysis. From COD balance in the process, the fraction of the feed-COD converted to the hydrogen-COD at acidogenic stage ranged from 7.9% to 9.3% and peaked at 6 gVSl-1day-1, whereas the fraction of feed-COD converted to the methane-COD at methanogenic stage ranged from 66.2% to 72.3% and peaked at 3 gVSl-1day-1.

• Journal of Microbiology
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• v.41 no.3
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• pp.248-251
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• 2003

Glutathione (GSH) is an important factor in determining tolerance against oxidative stress in living organisms. It is synthesized in two sequential reactions catalyzed by ${\gamma}$-glutamylcysteine synthetase (GCS) and glutathione synthetase (GS) in the presence of ATP. In this work, the effects of three different oxidative stresses were examined on GSH content and GSH-related enzyme activities in the fission yeast Schizosaccharomyces pombe. GSH content in S. pombe was significantly enhanced by treatment with hydrogen peroxide, ${\beta}$-naphthoflavone (BNF) and tert-butylhydroquinone (BHQ). Simultaneously, they greatly induced GCS and GS activity. However, they did not have any effects on glutathione reductase activity. These results suggest that GCS and GS activities in S. pombe are up-regulated by oxidative stress.

• Transactions of the Korean hydrogen and new energy society
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• v.32 no.6
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• pp.497-505
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• 2021

Water management is essential to improve the performance of proton exchange membrane fuel cells. This study targets to understand the characteristics of water concentration in proton exchange membrane fuel cells at a dynamic load variable environment. The fuel cell model was developed to simulate nonlinear water transport in membrane by the MATLAB/Simulink^® (MathWorks, Natick, MA, USA) platform, and it calculates water content in membrane, ionic conductivity, and predicts fuel cell performance through one-dimensional analysis.

• Transactions of the Korean hydrogen and new energy society
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• v.16 no.2
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• pp.122-129
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• 2005

The characteristics of hydrogen storage have been investigated in the Ti-Cr-Mo and Ti-Cr-V ternary alloys with bcc structure. The alloys were melted by arc furnace and remelted 4-5 times for homogeneity. The lattice parameters, microstructures and phases of the alloys were examined by SEM, EDX and XRD, and the Pressure-Composition isotherms of the alloys were measured. From these data the relationship of the maximum and effective hydrogen storage capacities vs. chemical composition, lattice parameter and the radius of tetrahedral site were analyzed and discussed. The results showed that all of these alloy, in the range of the this study, had mainly bcc solid solutions with small amount of Ti segregation due to a lower melting point of Ti compared with other elements. Lattice parameters of the alloys were very near to the atomic average values of lattice parameters of the constituent elements. It was also found that maximum hydrogen storage capacities of the Ti-Cr-Mo alloys increased with increasing Ti content and the radius of tetrahedral site but the effective hydrogen storage capacities decreased after showing the maximum. The hydrogen storage capacities of the Ti-Cr-V alloys were almost same even though the V contens were quite different from alloy to alloy and this could be attributed to the almost same Ti/Cr ratio of the alloys. The maximum effective hydrogen storage capacity of the Ti-Cr-Mo alloys was revealed at Ti content of about 40${\sim}$50 at% and radius of tetrahedral site of 0.43${\sim}$0.45 nm. The Ti-Cr-V alloys showed the hydrogen storage capacities of 3.0 wt% and effective hydrogen storage capacities of 1.5 wt%.

• Transactions of the Korean hydrogen and new energy society
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• v.22 no.4
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• pp.465-473
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• 2011

To find the optimum mixing ratio of WGS catalyst with $CO_2$ absorbent for SEWGS process, water gas shift reaction tests were carried out in a fluidized bed reactor using commercial WGS catalyst and sand (as a substitute for $CO_2$ absorbent). WGS catalyst content, gas velocity, and steam/CO ratio were considered as experimental variables. CO conversion increased as the catalyst content increased during water gas shift reaction. Variations of the CO conversion with the catalyst content were small at low gas velocity. However, those variations increased at higher gas velocity. Within experimental range of this study, the optimum operating condition(steam/CO ratio=3, gas velocity = 0.03 m/s, catalyst content=10 wt.%) to get high CO conversion and $CO_2$ capture efficiency was confirmed. Moreover, long time water gas shift reaction tests up to 20 hours were carried out for two cases (catalyst content = 10 and 20 wt.%) and we could conclude that the WGS reactivity at those conditions was maintained up to 20 hours.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2004.06a
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• pp.361-367
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• 2004

For assessment of tritium and radiocarbon ingestion dose to off site individuals, water, hydrogen, and carbon content of main farm produce of Korea were investigated to replace the existing data in K-DOSE60, the Offsite Dose Calculation Manual (ODCM) of Korea Hydro ＆ Nuclear Power Co. Ltd, (KHNP). Main items and weighting factors of farm produce were determined with the nationwide food intake data in 2001, 2002. Main farm produce were sampled around Kori, Wolsong, Ulchin, Younggwang nuclear power sites, Content of each produce was multiplied by weighting factor and summed up to make the weighted mean group value For grains, water, hydrogen, and carbon content was not much different from the existing data currently used in K-DOSE60, but root vegetables had 3.5 times more hydrogen, and leafy vegetables and fruits had 0.7∼1.3 times more or less water, hydrogen, and carbon contents than K-DOSE60.

• Applied Chemistry for Engineering
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• v.10 no.1
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• pp.98-104
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• 1999

In this work, we investigated hydrogen content, bond structure, and electrical properties of a-Si:H films prepared by ECR plasma CVD as a function of pressure. In general, the photo sensitivity of a-Si:H films prepared by CVD method decreases as the deposition rate increases, but the photo sensitivity of a-Si:H films prepared by ECR plasma deposition method increases as the deposition rate increases. In the same condition of microwave power, the ratio of $SiH_4/H_2$, and pressure, though film thickness increases linearly with deposition time and hydrogen content in the film is constant, photo conductivity can be decreased because $SiH_2$ bond is made more than SiH bond in the short reaction time. According to increase pressure in the chamber, SiH bond in the film increase and optical energy gap decrease. So, photo conductivity can be increased. But photo sensitivity decreased as dark conductivity increase. It must be grown in the condition of low pressure and hydrogen gas for taking the a-Si:H film of high quality.

• Journal of The Korean Society of Grassland and Forage Science
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• v.43 no.1
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• pp.56-61
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• 2023

The germination process is critical for plant growth and development and it is largely affected by environmental stress, especially salinity. Recently, hydrogen sulfide (H₂S) is well known to act as a signaling molecule in a defense mechanism against stress conditions but poorly understood regulating seed germination. In this study, the effects of NaHS (the H₂S donor) pretreatment on various biochemical (hydrogen peroxide (H₂O₂) content and amylase and protease activity) and physiological properties (germination rate) during seed germination of oilseed rape (Brassica napus L. cv. Mosa) were examined under salt stress. The seed germination and seedling growth of oilseed rape were inhibited by NaCl treatment but it was alleviated by NaHS pretreatment. The NaCl treatment increased H₂O₂ content leading to oxidative stress, but NaHS pre-treatments maintained much lower levels of H₂O₂ in germinating seeds under salt stress. Amylase activity, a starch degradation enzyme, significantly increased over 2-fold in control, NaHS pretreatment, and NaHS pretreatment under NaCl during seed germination compared to NaCl treatment. Protease activity was highly induced in NaHS-pretreated seeds compared to NaCl treatment, accompanied by a decrease in protein content. These results indicate that NaHS pretreatment could improve seed germination under salt stress conditions by decreasing H₂O₂ accumulation and activating the degradation of protein and starch to support seedling growth.

• Transactions of the Korean hydrogen and new energy society
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• v.34 no.5
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• pp.421-430
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• 2023

Fe-Ni-Pt nanocatalysts were loaded on carbon black powders which were synthesized by a spontaneous reduction reaction of iron (II) acetylacetonate, nickel (II) acetylacetonate and platinum (II) acetylacetonate. The morphology and the loading weight of Fe-Ni-Pt nanoparticles were characterized by transmission electron microscopy and thermogravimetric analyzer. The amount of Fe-Ni-Pt catalyst supported on the carbon black surface was about 6.42-9.28 wt%, and the higher the Fe content and the lower the Pt content, the higher the total amount of the metal catalyst supported. The Brunauer-Emmett-Teller Analysis (BET) specific surface area of carbon black itself without metal nanoparticles supported was 233.9 m²/g, and when metal nanoparticles were introduced, the specific surface area value was greatly reduced. This is because the metal nanocatalyst particles block the pore entrance of the carbon black, and thereby the catalytic activity of the metal catalysts generated inside the pores is reduced. From the I-V curves, as the content of the Pt nanocatalyst increased, the electrolytic properties of water increased, and the activity of the metal nanocatalyst was in the order of Pt > Ni > Fe.