• Journal of the Korea Organic Resources Recycling Association
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• v.14 no.1
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• pp.131-138
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• 2006

In this study, the optimum condition of pH was investigated on the hydrogen gas production under anaerobic fermentation process. The results of the experiment showed that the optimum condition was observed at pH 6, resulting in 1175.87 mL/L of hydrogen gas production rate and 22.51% theoretical hydrogen conversion ratio. Hydrogen gas production rate and theoretical hydrogen conversion ratio were 901.77 mL/L and 17.48 % respectively at pH 5. At pH 7 and 8, the production rate of hydrogen gas was little low as 82.15 mL/L. Among the organic acids from the sucrose fermentation, propionate was observed as the dominant acid at pH 7 and 8 but butyrate was the dominant at pH 5 and 6.

• 한국지구물리탐사학회:학술대회논문집
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• 2003.11a
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• pp.501-503
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• 2003

Soil-gas radon level and other atmospheric factors have been measured at residual soil profiles that overlie granite bedrock which consists of major geology in Korea for 6 months from November, 2000 to April, 2001. Seasonal variations of soil-gas radon concentration are generally of greater magnitude than day-to-day fluctuations. The highest radon concentrations of 5,131 pCi/L measured during winter season and the lowest radon concentrations of 107 pCi/L during spring season. Two study areas, Bongcheon-dong(granite bedrock) and Seongnam-Yongin(gneiss bedrock) were investigated to assess the radon potential according to their field survey and emanation tests. The mean values of radon decrease in sequentially from Suji-A(813 pCi/L)>Suji-B(757 pCi/L)>Bundang-B(691 pCi/L)>Bundang-A(643 pCi/L)>Bongcheon-dong(513 pCi/L). Estimated soil-gas radon potential using maximum radon emanation ratios of each study area decreases in the order of Bongcheondong(950 pCi/L)>Suji-B(524 pCi/L)>Bundang-A(437 pCi/)>Bundang-B(259 pCi/L)>Suji-A(230 pCi/L) areas. The values of indoor radon and its daughter product concentrations in Bongcheon-dong area show that indoor basement rooms in poor ventilation condition could be classified as extremely high radon risk location of more than 4 pCi/L Rn and 0.02 WL.

• Journal of the Korean Society of Marine Environment & Safety
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• v.27 no.2
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• pp.355-362
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• 2021

To facilitate low-pressure selective catalyst reduction (L.P SCR), a high exhaust-gas temperature of a four-stroke diesel engine for a ship's generator is required. This study aimed at reducing the exhaust-gas temperature by adjusting the valve open-close timing and fuel injection timing to satisfy the operating conditions of L.P SCR and prevent accidents associated with the generator engine due to high temperature. To lower exhaust-gas temperature, the angle of the camshaft was adjusted and the shim of the fuel injection pump was added. As a result, the maximum explosion pressure increased and the average of the turbocharger outlet temperature dropped. Considering the heat loss from the turbocharger outlet to the SCR inlet, the operation condition for L.P SCR was satisfied with 290 ℃. The study demonstrates that safe operation of a diesel generator can be achieved by lowering the exhaust-gas temperature.

• Asian-Australasian Journal of Animal Sciences
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• v.9 no.3
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• pp.247-254
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• 1996

Three stages of growth of Italian ryegrass (pre-blooming, P-B; early-blooming, E-B; and late-blooming, L-B) were used to evaluate the effect of maturity on in vitro digestion of dry matter, fiber components and gas production. The rumen digestibility and gas production values were obtained by incubation of each sample in the rumen fluid of sheep for 12, 24, 36, 48 and 72 hr, respectively. The results showed that digestibility of dry matter (DM) significantly reduced (p < 0.05) as advancing maturity of the grass. Similarly, the digestibility of neutral detergent fiber (NDF) and acid detergent fiber (ADF) also significantly decreased (p < 0.05) with advancing maturity at all incubation times. However, the effect of maturity on digestibility of cellulose and hemicellulose was only detected when the samples were incubated more than 36 hr, where L-B was lower than P-B and E-B. Potential digestibility of nutrients, the maximum digestibility attainable in the rumen theoretically, was also higher at P-B than those of E-B and L-B. The amount of gas produced by microbial fermentation was closely related to the extent of DM digestion, and it was negatively correlated with advancing maturity of the grass.

• Journal of the Korea Organic Resources Recycling Association
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• v.8 no.3
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• pp.89-96
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• 2000

Waste oyster shell was used to study the applicability on anaerobic composting of garbage. Experiment was conducted with five anaerobic reactors. After garbage and compost for inoculation were mixed, waste oyster shell was added into mixed waste in mesophillic temperature for 60 days with 30%, 60% respectively. The amount of produced methane gas, gas composition, organic removal efficiency and pH were measured. Result showed that the amounts of produced gas were 0.62 l /g-VS in R-1, 0.63 l /g-VS in R-2, 0.16 l /g-VS in R-3, 0.75 l /g-VS in R-4, 0.21 l /g-VS in R-5 and the amounts of produced methane gas were 0.32 l /g-VS in R-1, 0.37 l /g-VS in R-2, 0.04 l /g-VS in R-3, 0.42 l /g-VS in R-4, 0.05 l /g-VS in R-5. Proportion of mathane gas which determines the efficiency of anaerobic composting was over 55%. pH were 6.0~8.0 in R-2 and R-4 which contained 30% of waste oyster shell and pH were increased over 8.5 in R-3 and R-5 which contained 60% of waste oyster shell. Since pH were so high and it had a negative effect on microbial growth, anaerobic reaction were not well operated in R-3 and R-5.

• Journal of Korean Society of Environmental Engineers
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• v.29 no.1
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• pp.54-61
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• 2007

The influences of pH were investigated for anaerobic hydrogen gas production under the constant pH condition ranged from pH 3 to 10. Carbon dioxide and hydrogen gas were main components of the gas but methane was not detected in the produced gas when sucrose was added in enrichment medium. When the modified Gompartz equation was applied for the statistical analysis of experimental data, a hydrogen production potential and maximum gas production rate at pH 5 were 1,182 mL and 112.46 mL/g dry wt biomass/hr. The hydrogen conversion ratio was 22.56%. The butyrate/acetate ratios at pH 5 and pH 6 are 1.63 and 0.38. Higher butyrate/acetate ratio produced more hydrogen gas generation. The Haldane equation model was used to find the optimum pH and fitted well with the experimental data$(r^2=0.98)$. The optimum pH and specific hydrogen production were 5.5 and 119.61 mL/g VSS/h.

• Journal of the Korean Society of Combustion
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• v.18 no.2
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• pp.17-22
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• 2013

In this study, we tested the absorption of $CO_2$ in combustion gas into an alkaline wastewater to simultaneously control $CO_2$ and wastewater. During the experiment, we investigated the effects of operating parameters on neutralization characteristics of the wastewater by using $CO_2$ in a bench-scale semi-batch jet loop reactor (0.1 m diameter and 1.0 m in height). The operating parameters investigated in the study are gas flow rate of 1.0-2.0 L/min, liquid recirculation flow rate of 4-32 L/min, and liquid temperature of $20-25^{\circ}C$. It was shown that the initial pH of wastewater rapidly decreased with increased gas flow rate for a given liquid recirculation flow rate. This was due to the increase in the gas holdup and the interfacial area at higher gas flow rate in the reactor. At constant gas flow rate, the time required to neutralize the wastewater initial pH of 10.1 decreased with liquid recirculation flow rate ($Q_L$), reached a minimum value in the range of $Q_L$ = 16-24 L/min, and then increased with further increase in $Q_L$. Further, the time required to neutralize the wastewater was shortened at higher temperatures.

• Journal of the Korean Society of Combustion
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• v.18 no.3
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• pp.38-43
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• 2013

In this study, we tested the absorption of $CO_2$ in combustion gas into an alkaline wastewater to simultaneously control $CO_2$ and wastewater. During the experiment, we investigated the effects of operating parameters on neutralization characteristics of the wastewater by using $CO_2$ in a bench-scale semi-batch jet loop reactor (0.1 m diameter and 1.0 m in height). The operating parameters investigated in the study are gas flow rate of 1.0-2.0 L/min, liquid recirculation flow rate of 4-32 L/min, and liquid temperature of $20-25^{\circ}C$. It was shown that the initial pH of wastewater rapidly decreased with increased gas flow rate for a given liquid recirculation flow rate. This was due to the increase in the gas holdup and the interfacial area at higher gas flow rate in the reactor. At constant gas flow rate, the time required to neutralize the wastewater initial pH of 10.1 decreased with liquid recirculation flow rate ($Q_L$), reached a minimum value in the range of $Q_L$ = 16-24 L/min, and then increased with further increase in $Q_L$. Further, the time required to neutralize the wastewater was shortened at higher temperatures.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.4 no.2
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• pp.116-122
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• 1992

The purpose of this paper is to determine the cut off flowrate regions of the overflow valve in using L.P gas vassels. The experimental methods were employed to measure the cut off flowrate in the state of constant pressure by using the $N_2$ gas. 1) To determine the optimum cut off flowrate regions, Hose length are required 0.5 meters. 2) Cut off fowrate regions about the each pressure can be suggested as follows. A) Cut off flowrate rigions are $2.0-4.0m^3/hr$ at the pressure of the $1Kg_f/cm^2$. B) Cut off flowrate rigions are$7.0-10.0m^3/hr$ at the pressure of the $10Kg_f/cm^2$.

• Asian-Australasian Journal of Animal Sciences
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• v.18 no.2
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• pp.203-208
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• 2005

The aim of this experiment was to determine the chemical composition of six commonly utilized fodder trees and shrub species in Turkey, namely Glycrrhiza glabra L, Arbutus andrachne, Carpinus betilus, Juniperus communis, Quercus libari L and Pistica lentiscus and its relationship with gas production and estimated parameters when incubated with rumen fluid in vitro. There were significant (p<0.001) differences between leaves in terms of crude protein (CP), acid detergent fiber (ADF), total condensed tannin (TCT), bound condensed tannin (BCT) and soluble condensed tannin (SCT). Crude protein contents ranged from 5.74% (Juniperus communis) to 12.59% (Glycrrhiza glabra L). Acid detergent fiber contents ranged from 25.14% (Glycrrhiza glabra L) to 39.23% (Juniperus communis). Total condensed tannin (TCT) contents of leaves ranged from 4.34% (Quercus libari L) to 20.34% (Juniperus communis). Acid detergent fiber (ADF) and total condensed tannin contents of leaves were negatively correlated with gas productions and some estimated parameters. Potential gas productions (A) of Glycrrhiza glabra L, Arbutus andrachne, Quercus libari L and Pistica lentiscus were significantly (p<0.001) higher than those of Carpinus betilus and Juniperus communis whereas gas production rate (${\mu}_{24}$) of Pistica lentiscus was significantly (p<0.001) higher than the others. Time (h) to produce 50% of total gas pool size ($T_{50}$) of Juniperus communis was significantly (p<0.001) lower than that of Carpinus betilus whereas time (h) to produce 90% of total gas pool size ($T_{90}$) of Juniperus communis was significantly lower than the others except for Pistica lentiscus. The metabolizable energy (ME) contents of leaves ranged from 8.86 to 10.39 MJ $kg^{-1}$ DM. The results obtained in this study suggested that browse species had a significant effect on chemical composition, gas production and estimated parameters of leaves. Leaves from Glycrrhiza glabra L with a considerable amount of CP had a high rank value in terms of ME. Therefore leaves from Glycrrhiza glabra L may have a high potential value for small ruminant animals in terms of rumen and whole digestibility. Leaves from other species studied require protein supplementation when they are the only feed consumed by ruminant animals.