• 한국정보디스플레이학회:학술대회논문집
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• 2006.08a
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• pp.375-378
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• 2006

Characteristics of doped MgO layer deposited under hydrogen atmosphere were investigated. Hydrogen gas was introduced during e-beam evaporation of doped MgO and its effects on microstructure, cathodoluminescence, discharge voltages and effective yield of secondary electron emission were examined. The results indicated that the hydrogen influences and doped impurities the concentration and energy levels of defects in MgO layer and that affects the luminance efficiency and discharge delays of the panels significantly.

• Journal of the Korean Society for Precision Engineering
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• v.18 no.1
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• pp.129-138
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• 2001

This study examined the effects of the annealing heat treatments on the mechanical properties of the Invar(Fe-36%Ni Alloy) materials. Invar materials were annealed at various temperatures range 900~120$0^{\circ}C$ in vacuum(10-4Torr) and hydrogen atmospheres. And annealing conditions were changed by cooling rate and holding time at 110$0^{\circ}C$. The grain size of rolled Invar materials was very fine but those of annealed Invar materials at 900~120$0^{\circ}C$ in vacuum and hydrogen atmosphere increased with increasing annealing temperature. The micro-vickers hardness values of annealed Invar materials were decreased about 15% that of the rolled Invar materials, regardless of the various of annealing temperatures, atmosphere(vacuum, hydrogen) and annealing conditions. The tensile strength and yield strength of annealed Invar materials at 900~120$0^{\circ}C$ in vacuum and hydrogen atmosphere were decreased 10.0~14.4% and 34.6~39.1% those of the rolled Invar materials, respectively. The strength ratio(tensile strength/ yield strength) of annealed Invar materials was improved to 1.7~1.8 from the value of 1.2~1.3 of rolled Invar materials. The degree of spring back of annealed Invar materials was about 50% of the rolled Invar materials, regardless of the various of annealing temperatures, atmosphere(vacuum, hydrogen) and annealing conditions.

• Applied Chemistry for Engineering
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• v.35 no.2
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• pp.107-114
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• 2024

In order to produce high-yield pitch-based activated carbon, pitch was synthesized by blending pyrolysis fuel oil (PFO) and coal-tar. Pitch was synthesized by varying the amount of coal-tar from 0~20% compared to PFO and reacting at 380~420 ℃ for 3 h. The synthesized pitch had a softening point between 80 and 260 ℃, and yields ranged from 10 to 40%. At all synthesis temperatures, as the coal-tar blending ratio increased, the yield increased and the softening point decreased. After considering the selected pitches (softening points: 230~260 ℃), pitches containing coal-tar were more volatile at a low boiling point and had a higher residual carbon content. This is a difference in the composition of coal-tar and PFO, and it was con- firmed that coal-tar has a lot of aromatics and PFO has a lot of aliphatics. The selected pitch was heated to 950 ℃ in a tubular reactor and physically activated with steam for 1 hour. Activated carbon containing coal-tar showed higher yield and microporosity compared to only PFO. In this study, the effect of increasing activated carbon yield by blending pitch raw materials was confirmed, and the physical activation characteristics according to the coal-tar mixing ratio were examined.

• Microbiology and Biotechnology Letters
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• v.37 no.2
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• pp.176-182
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• 2009

Hydrogen producing bacterium, strain MeL 6-2 was isolated from the sludge of the factory areas in Anyang through the acclimation in basal salt medium (BSM) supplemented with 10 g/L of sucrose. Isolated strain MeL 6-2 was a facultative anaerobe which could grow in both aerobic and anaerobic environments. An aerobically grown pure culture isolated from enriched culture was analyzed by 16S rDNA sequencing and identified as Rhodopseudomonas sp. MeL 6-2. Effects of the concentrations of glucose and sucrose on the hydrogen production rate and the hydrogen production yield were investigated. When glucose in the range of 1~12 g/L was supplemented to the BSM, strain MeL 6-2 could grow without lag phase. An increased glucose concentration increased the specific hydrogen production rate linearly to $4.2\;mmol-H_2{\cdot}L^{-1}{\cdot}h^{-1}$ at 10 g/L, and $60\;mmol-H_2{\cdot}mg-DCW^{-1}{\cdot}h^{-1}$, but decreased slightly as the concentration increased to 12 g/L. The hydrogen production yield was maintained over a range from 2.6 to $3.1\;mol-H_2{\cdot}mol-glucose^{-1}$. When sucrose in the range of 1~12 g/L was supplemented to the BSM, strain MeL 6-2 could grow after ten hours. An increased sucrose concentration increased the specific hydrogen production rate and the hydrogen production yield to $163\;mmol-H_2{\cdot}mg-DCW^{-1}{\cdot}h^{-1}$ and to $4.5\;mol-H_2{\cdot}mol-sucrose^{-1}$, respectively.

• Journal of Korean Society of Environmental Engineers
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• v.28 no.9
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• pp.911-916
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• 2006

The influence of substrate concentration and hydraulic retention time(HRT) on the hydrogen production by anaerobic microflora was investigated by conducting three series of continuous experiments the individual influences of substrate concentration and HRT. In series I, substrate concentration was increased from 3 to 27 g-glucose/L keeping HRT at 8 hr. Series II and III carried out same condition with series I at HRT of 16 hr and 24 hr, respectively. The effects of HRT and substrate concentration on the hydrogen production yield were analyzed by quadratic model. The maximum hydrogen production yield of 2.05 mol $H_2/mol$ glucose was found at the HRT of 9.6 hr and the substrate concentration of 15.4 g/L. The relationship between HRT and substrate concentration on hydrogen production yield as displayed a saddle shape in the response surface plot. Optimum HRT and substrate concentration are observed at in the range of 5 and 14 hr, at between 13 and 17 g/L, respectively, for the hydrogen production yield being 2 mol $H_2/mol$ glucose. The concentrations of organic acids increased with the increase of the amount of glucose consumption. Acetic acid and butyric acid were the main by-products from the glucose degradation.

• Journal of the Korean Institute of Gas
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• v.24 no.6
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• pp.61-69
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• 2020

This paper is a study of the behavior characteristics that occur in the hydrogen storage vessel TYPE 1 according to pressure and temperature conditions by FEM(Finite element method). Von Mises stress (VMS) generated at the highest pressure was compared with Yield strength (YS) of the material for structural safety assessment of the container, and the results of plastic strain energy density (PSED) were analyzed as basic data for life expectancy. According to the analysis results, the safety of the hydrogen gas storage vessel is not ensured due to the occurrence of VMS higher than the yield strength on the bottom of the storage container at a gas pressure of 40 Mpa or higher. In addition, the results of VMS caused by temperature conditions are very low and the behavior by temperature can be ignored. The maximum pressure of VMS/YS below 1 is calculated to be about 30 Mpa, indicating that the hydrogen storage container subject to this paper should be managed with a gas charging pressure of less than 30 Mpa.

• Transactions of the Korean hydrogen and new energy society
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• v.25 no.5
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• pp.468-474
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• 2014

This study was conducted to evaluate the characteristics of mesophilic fermentative $H_2$ production from food waste which was treated by food waste disposer. It was found that $H_2$ yield and lag phase were affected by particle size of food waste. The $H_2$ yield decreased with increasing particle size while lag phase increased. The maximum $H_2$ yield was found $0.584{\pm}0.03$ mol $H_2$/mol hexose at particle size smaller than 0.30 mm. The $H_2$ production rate was also affected by chemical composition of food waste. The $H_2$ production rate linearly decreased with increasing proteins to carbohydrates ratio(P/C ratio) where the maximum value was $0.031{\pm}0.006$ mol $H_2$/mol hexose h at 0.17.

• Asian-Australasian Journal of Animal Sciences
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• v.25 no.12
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• pp.1691-1700
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• 2012

The experiment studied the effect of harvesting frequencies and varieties on yield, chemical composition and hydrogen cyanide content in cassava foliage. Foliage from three cassava varieties, K94 (very bitter), K98-7 (medium bitter) and a local (sweet), were harvested in three different cutting cycles, at 3, 6 and 9 months; 6 and 9 months and 9 months after planting, in a 2-yr experiment carried out in Hanoi, Vietnam. Increasing the harvesting frequency increased dry matter (DM) and crude protein (CP) production in cassava foliage. The K94 variety produced higher foliage yields than the other two varieties. Dry matter, neutral detergent fibre (NDF), acid detergent fibre (ADF) and total tannin content increased with months to the first harvest, whereas CP content decreased. Hydrogen cyanide (HCN) content was lower at the first harvest than at later harvests for all cutting cycles. At subsequent harvests the content of total tannins tended to decline, while HCN content increased (p<0.05). Chemical composition differed somewhat across varieties except for total tannins and ash. Dry matter, NDF, ADF and total tannins were higher in fully matured leaves, while CP and HCN were lower in developing leaves.

• Transactions of the Korean hydrogen and new energy society
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• v.25 no.4
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• pp.337-343
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• 2014

This study was conducted to evaluate the characteristics of dark fermentative $H_2$ production from microalgae (Chlorella vulgaris) using batch reactors under mesophilic (25, $35^{\circ}C$) and thermophilic (45, $55^{\circ}C$) conditions. The $H_2$ yield and $H_2$ production rate increased with increasing temperature. The maximum $H_2$ yield and $H_2$ production rate were 56.77 mL $H_2/g$ dcw, 3.33 mL $H_2/g\;dcw{\cdot}h$ at $55^{\circ}C$, respectively. The activation energy calculated using Arrhenius equation was 36.24 kcal/mol, which was higher than that of dark $H_2$ fermentation of glucose by anaerobic mixed culture. Although the concentration of butyrate was maintained, the concentrations of lactate and acetate increased with increasing temperature. The $H_2$ yield was linearly proportional to acetate/ butyrate ratio.

• Journal of the Korea Organic Resources Recycling Association
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• v.19 no.1
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• pp.102-108
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• 2011

Characteristics of hydrogen production from various food wastes in anaerobic batch reactors were evaluated to assess the energy potential of organic wastes. Organic wastes which were used in this study were scallion as vegetable, apple as fruit, rice as grain and pork as meat. Ultimate hydrogen yield of scallion, apple, rice and pork were 0.46, 0.47, 0.62 and $0.05mol\;H_2/mol\;hexose$, respectively. On the other hand, hydrogen production rates of scallion, apple, rice and pork were 0.013, 0.021, 0.014 and $0.005mol\;H_2/mol\;hexose/h$, respectively. These results indicated that anaerobic hydrogen fermentation from food waste except for meat was effective in removing organic material as well as producing renewable energy. Volatile fatty acids increased as hydraulic retention time was increased. In the hydrogen fermentation, acidification degree of rice was measured as the highest rate of 75.8% whereas pork was found as the lowest rate of 35.2%.