• Journal of environmental and Sanitary engineering
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• v.4 no.2 s.7
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• pp.91-99
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• 1989

An anaerobic acidogenic fermentation experiment was carried out in order to investigate the distribution of volatile acid products and gas generations with varing temperatures and pH values. The experiment was carried out using $1\%$ glucose as substrate and a pair of 3.5 liter vessle as bench scale batch reactors. The reactors were operated for 7 days at 25, 30 and $35^{\circ}C$ and at pH values of 4.0, 4.5, 5.0, 5.5 and 6.0 at each temperature conditions. Major products at all experiment pH's at $35^{\circ}C$ were acetic acids and butyric acids which together composed around $90^{\circ}F$ of total product acids. At higher pH values at $35^{\circ}C$, propionic acid reached around $10\%$. At all experiment conditions, 52 to $55\%$ of generated gases comprised of hydrogen gas and 45 to $48\%$ of carbon dioxide. With temperature increase from 25 to $35^{\circ}C$, the production rate of acetic acid increased 2.9 fold, butyric acid 22 fold, hydrogen gas 2.0 fold and carbon dioxide gas 2.3 fold. Optimum reaction conditions for highest production of acetic acid and hydrogen gas was determined to be pH 5.5 at $35^{\circ}C$.

• Journal of Sensor Science and Technology
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• v.31 no.5
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• pp.337-342
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• 2022

Hydrogen (H₂) gas is widely preferred for use as a renewable energy source owing to its characteristics such as environmental friendliness and a high energy density. However, H₂ can easily reverse or explode due to minor external factors. Therefore, H₂ gas monitoring is crucial, especially when the H₂ concentration is close to the lower explosive limit. In this study, metal oxide materials and their p-n heterojunctions were synthesized by a hydrothermal-assisted dip-coating method. The synthesized thin films were used as sensing materials for H₂ gas. When the H₂ concentration was varied, all metal oxide materials exhibited different gas sensitivities. The performance of the metal oxide gas sensor was analyzed to identify parameters that could improve the performance, such as the choice of the metal oxide material, effect of the p-n heterojunctions, and operating temperature conditions of the gas sensor. The experimental results demonstrated that a CuO/ZnO gas sensor with a p-n heterojunction exhibited a high sensitivity and fast response time (134.9% and 8 s, respectively) to 5% H₂ gas at an operating temperature of 300℃.

• Transactions of the Korean hydrogen and new energy society
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• v.31 no.5
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• pp.405-410
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• 2020

In this literature, we are introduce a basic design of multi energy hub based on natural gas governor station. Multi energy hub consists of turbo expender generator, phosphoric acid fuel cell, pressure swing adsorption, H₂ charging station, utilities and etc. We design a hybrid energy hub system that provides energy using these complex energies, and calculates the amount of electricity that can be produced and the amount of hydrogen charged through the process analysis. TEG and phosphoric acid fuel cell produce 2,290 to 2,380 kW and can supply electricity to 500 houses. In addition, By-product H₂ gas is refined to H₂ vehicle fuel. This will help maximize the balance of energy demand and supply and improve national energy efficiency by integrating unused decompression energy power generation technology and various power generation/heat source technologies.

• Journal of the Korean Society for Heat Treatment
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• v.20 no.5
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• pp.237-242
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• 2007

Friction coefficient of SM45C steel was surprisingly reduced with $H_2S$ and $C_3H_8$ gas during plasma sulf-nitriding. During the plasma sulf-nitriding, 100-700 sccm of $H_2S$ gas and 100 sccm of $C_3H_8$ gas were added and working pressure and temperature were 2 torr, $500-550^{\circ}C$, respectively. As $H_2S$ gas amount increased over 500 sccm, flake-like structures were developed on top of the nitriding layer and grain size of the nitriding layer were about 100 nm. The friction coefficient for the sample treated plasma sulf-nitriding under $N_2-H_2S$ gas was 0.4 - 0.5. The structure became more finer and amorphous-like along with $N_2-H_2S-C_3H_8$ gas and the nano-sized surface microstructures resulted in high hardness and significantly low friction coefficient of 0.2.

• Journal of the Korean Society for Precision Engineering
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• v.15 no.7
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• pp.69-77
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• 1998

Development on the mechanical properties of steel sheet for the automobile body panel is very important in the BAF(Batch annealing furnace) annealing process. Because of the heat treatment method in the BAF, mechanical properties were decided on the heat treatment method of the coil. So, we tested on the development of mechanical properties according to heat treatment method at the annealing furnace using the In atmospheric gas($H_2$ : 75%, $N_2$ : 25%) and the HNx atmospheric gas($H_2$ : 5%, $N_2$ : 95%) We confirmed the following characteristics, mechanical properties were changed under the influence of the annealing cycle and the atmospheric gas. And, we have some result according to heat treatment method. Elongation of the mechanical properties in the HNx BAF is higher than the Ax BAF. But tensile strength and hardness is higher than the HNx BAF.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.11 no.4
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• pp.288-292
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• 1998

In this paper, we fabricated $SnO_2$ composite ceramics doped with 0~20mol% $SnO_2$ of bulk type to investigate the CO and $H_2$ gas sensitivity in various composition, temperature, and concentration of CO and $H_2$ gas. At the temperature range from $100^{\circ}C\sim425^{\circ}C$, the measured 1000ppm and 250ppm CO gas sensitivities of $SiO_2-SnO_2$composite ceramics were about 1.0~7.6 and 1.0~5.6, respectively. These values were about 1.0~1.5 times larger than pure $SnO_2$. The maximum 1000ppm CO gas sensitivity of $SiO_2-SnO_2$composites were measured around $325^{\circ}C$. At the temperature range from $270^{\circ}C\sim380^{\circ}C$, the 1000ppm and 500ppm $H_2$gas sensitivities of $SiO_2-SnO_2$ composites were about 2.9~21.2 and 2.1~11.3, respectively. Also the maximum 1000, 500 ppm $H_2$ gas sensitivities of samples were measured around.

• Journal of the Korean Vacuum Society
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• v.9 no.3
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• pp.197-206
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• 2000

The deposition characteristics of MOCVD Cu using the (hfac)Cu(1,1-COD)(1,1,1,5,5,5-hexafluoro-2,4-pentadionato Cu(I) 1,5-cyclooctadine) have been investigated in terms of the effects of carrier gas such as hydrogen and argon as well as the effects of H(hfac) ligand addition. MOCVD Cu using a hydrogen carrier gas led to a higher deposition rate and lower resistivity than an argon carrier gas system. The improvement in the surface roughness of the MOCVD Cu films and the (111) preferred orientation texture was obtained by using a hydrogen carrier gas. However, the adhesion characteristics of the films showed relatively weaker compared to the Ar carrier gas system, probably due to the larger amount of F content in the films, which was confirmed by the AES analyses. When an additional H(hfac) ligand was added, the deposition rate was significantly enhanced in the case of an argon + H(hfac) carrier gas system while significant change in the deposition rate of MOCVD Cu was not observed in the case of the hydrogen carrier gas system. However, the addition of H(hfac) in both carrier gases led to lowering the resistivity of the MOCVD Cu films. In conclusion, this paper suggests the deposition mechanism of MOCVD Cu and is expected to contribute to the enhancement of smooth Cu films with a low resistivity by manipulating the deposition conditions such as the carrier gas and addition of H(hfac) ligand.

• Journal of the Korean Ceramic Society
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• v.27 no.5
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• pp.638-644
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• 1990

The C3H8 gas sensitivities of SnO2, Pd-SnO2, Pt-SnO2 gas sensor are looked over with the impregnation method of PdCl2, H2PtCl6 solution on SnO2. The Cl- ion due to incomplete decomposition of PdCl2 at 80$0^{\circ}C$ for 30 min decrease the C3H8 gas sensitivity of SnO2, and the sensitivity is increased by the impreganation of H2PtCl6 solution on SnO2 because of its lower decomposition temperature compared with PdCl2. The C3H8 gas sensitivities of Pd-SnO2, Pt-SnO2 impregnated slightly after 1st sintering are larger than that of pure SnO2 sensor because very small amount of Cl- ion exist in sample due to smaller amount of impregnaiton.

• Journal of Sensor Science and Technology
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• v.23 no.6
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• pp.397-401
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• 2014

This paper describes the fabrication and characteristics of $C_2H_2$ gas sensor based on Ag-doped hierarchical ZnO nanostructures. In this work, a pure hierarchical ZnO structure was prepared using a simple hydrothermal method, and Ag nanoparticles doped the hierarchical ZnO structure were uniformly synthesized through photochemical route. The synthesized samples were characterized by SEM, TEM, EDS, XRD and PL spectra. Average size of prepared ZnO structures was around $2{\sim}3{\mu}m$ and showed highly uniform. The average size of Ag nanoparticles was 70 nm. The gas sensing properties of as-prepared products were investigated using resistivity-type gas sensors. 5 at% Ag-doped ZnO based sensors exhibited good performances for $C_2H_2$ gas in comparison with the un-doped one. The sensor based on Ag-doped hierarchical ZnO structures had linear response property from 5~1000 ppm of $C_2H_2$ concentration at working temperature of $200^{\circ}C$. The response values with 100 ppm $C_2H_2$ at $200^{\circ}C$ were 10% and 75% for pure and 5 at% Ag-doped hierarchical ZnO nanostructures, respectively. Moreover, the device showed excellent selectivity towards to $C_2H_2$ gas at optimal working temperature of $200^{\circ}C$.

• Journal of the Korean Ceramic Society
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• v.29 no.12
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• pp.990-996
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• 1992

Chemical vapor deposition of ATO from SnCl4-SbCl5-H2O gas mixture was investigated with thermodynamic and experimental analyses. Electrical conductivity of the ATO film was much improved under deposition conditions of low input-gas ratio, Psbcl5/Psbcl4. This increase of the conductivity was attributed to donor electrons produced mainly by the pentavalent Sb ions in SnO2 lattice. However high input-gas ratio conditions produced an ATO film consisting of a mixture of SnO2 and very fine Sb2O5 phase. It was found that the deterioration of electrical conductivity and optical transmission of the film was caused by the deposition of fine Sb2O5 phase in the SnO2 matrix.