• Journal of the Korean earth science society
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• v.35 no.7
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• pp.543-553
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• 2014

The environmental behavior of $SO_2$ was investigated in terms of the factors affecting the temporal variabilities by analyzing the data sets obtained from the Yongsan district in Seoul from 2004 till 2013. To this end, the relationship between $SO_2$ and relevant parameters including particulate matters (such as $PM_{2.5}$, $PM_{10}$, and TSP (total suspended particulates)) and gaseous components ($CH_4$, CO, THC (total hydrocarbon), NMHC (non-methane hydrocarbon), NO, $NO_2$, NOx, and $O_3$) was investigated in several aspects. Over a decade, the annual mean concentrations of $SO_2$ varied in the range of $4.36-5.86nmole\;mole^{-1}$ (min-max) which was about five times lower than the regulation guideline set for the air quality management in Korea. In fact, this pattern greatly contrasts with some other air pollutants of which concentrations exceeded their guideline values significantly. According to our analysis, $SO_2$ was strongly correlated to the temperature and other relevant parameters. The overall results of this study confirm that the administrative regulation of $SO_2$ levels has been made effectively relative to other airborne pollutants.

• Asian-Australasian Journal of Animal Sciences
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• v.29 no.8
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• pp.1111-1119
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• 2016

Mao seed is a by-product of the wine and juice industry, which could be used in animal nutrition. The current study was designed to determine the effect of supplementation of mao (Antidesma thwaitesianum Muell. Arg.) seed meal (MOSM) containing condensed tannins (CT) on rumen fermentation, nitrogen (N) utilization and microbial protein synthesis in goats. Four crossbred (Thai Native${\times}$Anglo Nubian) goats with initial body weight (BW) $20{\pm}2kg$ were randomly assigned to a $4{\times}4$ Latin square design. The four dietary treatments were MOSM supplementation at 0%, 0.8%, 1.6%, and 2.4% of total dry matter (DM) intake, respectively. During the experimental periods, all goats were fed a diet containing roughage to concentrate ratio of 60:40 at 3.0% BW/d and pangola grass hay was used as a roughage source. Results showed that supplementation with MOSM did not affect feed intake, nutrient intakes and apparent nutrient digestibility (p>0.05). In addition, ruminal pH and ammonia nitrogen ($NH_3$-N) were not influenced by MOSM supplementation, whilst blood urea nitrogen was decreased quadraticly (p<0.05) in goats supplemented with MOSM at 2.4% of total DM intake. Propionate was increased linearly with MOSM supplementation, whereas acetate and butyrate were remained the same. Moreover, estimated ruminal methane ($CH_4$) was decreased linearly (p<0.05) when goats were fed with MOSM at 1.6% and 2.4% of total DM intake. Numbers of bacteria and protozoa were similar among treatments (p>0.05). There were linear decreases in urinary N (p<0.01) and total N excretion (p<0.01) by MOSM supplementation. Furthermore, N retention was increased linearly (p<0.05) when goats were fed with MOSM supplementation at 1.6% and 2.4% of total DM intake. Microbial protein synthesis were not significantly different among treatments (p>0.05). From the current study, it can be concluded that supplementation of MOSM at 1.6% to 2.4% of total DM intake can be used to modify ruminal fermentation, especially propionate and N utilization in goats, without affecting the nutrient digestibility, microbial populations and microbial protein synthesis.

• Transactions of the Korean hydrogen and new energy society
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• v.17 no.4
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• pp.379-388
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• 2006

Two mesophilic trickling bed bioreactors filled with two different types of media, hydrophilic- and hydrophobic-cubes, were designed and conducted for hydrogen production under the anaerobic fermentation of sucrose. Each bioreactor consisted of the column packed with polymeric cubes and inoculated with heat-treated sludge obtained from anaerobic digestion tank. A defined medium containing sucrose was fed by the different hydraulic retention time(HRT), and recycle rate. Hydrogen concentrations in gas-phase were constant, averaging 40% of biogas throughout the operation. Hydrogen production rate was increased till $10.5\;L{\cdot}h^{-1}{\cdot}L^{-1}$ of bioreactor when influent sucrose concentrations and recycle rates were varied. At the same time, the hydrogen production rate with hydrophobic media application was higher than its hydrophilic media application. No methane was detected when the reactor was under a normal operation. The major fermentation by-products in the liquid effluent of the both trickling biofilters were acetate, butyrate and lactate. In order to run in the long term operation of both reactor filled with hydrophilic and hydrophobic media, biofilm accumulation on hydrophilic media and biogas produced should be controlled through some process such as periodical backwashing or gas-purging. Four sample were collected from each reactor on the opposite hydrogen production rate, and their bacterial communities were compared by terminal restriction fragment length polymorphism (T-RFLP) analysis of PCR products generated using bacterial 16s rRNA gene primers (8f and 926r). It was expressed a marked difference in bacterial communities of both reactors. The trickling bed bioreactor with hydrophobic media demonstrates the feasibility of the process to produce hydrogen gas. A likely application of this reactor technology can be hydrogen gas recovery from pre-treatment of high carbohydrate-containing wastewaters.

• Applied Chemistry for Engineering
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• v.19 no.1
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• pp.17-26
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• 2008

With the effectuation of Kyoto Protocol on the United Nations Framework Convention on the Climate Change, the emission reduction of greenhouse gases became an urgent issue and has been competitively secured among countries as the form of certificates through clean development mechanism (CDM) or joint implementation (JI). Nitrous oxide ($N_2O$) is one of the major greenhouse gases along with carbon dioxide ($CO_2$) and methane ($CH_4$) having warming potential 310 times that of carbon dioxide and chemically very stable in the atmosphere to give a life time of more than 120 years so that it reaches to the stratosphere to act as an ozone depleting substance. $N_2O$ hardly decomposes and thus, besides to the adoption of thermal decomposition at high temperature, selective catalytic reduction methods are usually used at temperatures over $400^{\circ}C$ in which the presence of NOx acts as a major impeding material in the decomposition process. In this article, the sources of various $N_2O$ generation, catalytic reduction processes and the status and trends of emission trade with CDM projects for greenhouse gas reduction are summarized and discussed on a condensed basis.

• Tunnel and Underground Space
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• v.26 no.2
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• pp.59-67
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• 2016

In this paper, we perform a numerical analysis to evaluate the potential of fault reactivation during gas production from hydrate bearing sediments and the moment magnitude of induced seismicity. For the numerical analysis, sequential coupling of TOUGH+Hydrate and FLAC3D was used and the change in effective stress and consequent geomechanical deformation including fault reactivation was simulated by assuming that Mohr-Coulomb shear resistance criterion is valid. From the test production simulation of 30 days, we showed that pore pressure reduction as well as effective stress change hardly induces the fault reactivation in the vicinity of a production well. We also investigated the influence of stress state conditions to a fault reactivation, and showed that normal fault stress regime, where vertical stress is relatively greater than horizontal, may have the largest potential for the reactivation. We tested one simulation that earthquake can be induced during gas production and calculated the moment magnitude of the seismicity. Our calculation presented that all the magnitudes from the calculation were negative values, which indicates that induced earthquakes can be grouped into micro-seismic and as small as hardly perceived by human beings. However, it should be noted that the current simulation was carried out using the highly simplified geometric model and assumptions such that the further simulations for a scheduled test production and commercial scale production considering complex geometric conditions may produce different results.

• Korean Journal of Soil Science and Fertilizer
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• v.47 no.5
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• pp.374-380
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• 2014

To estimate greenhouse gas (GHG) emission, the inventory of rice cultivation at the farming without agricultural chemicals was established from farmers in Gunsan, Jeonbuk province in 2011~2012. The objectives of this study were to calculate carbon footprint and analyse the major factor of GHGs. To do this, we carried out a sensitivity analysis using the analyzed main factors of GHGs and estimated the mitigation potential of GHGs. Also we suggested agricultural methods to reduce GHGs that can be appled by farmers at this region. At the farming system without agricultural chemicals, carbon footprint of rice production unit of 1 kg was 2.15 kg $CO_2.-eq.kg^{-1}$. Although the amount of carbon dioxide ($CO_2$) emission was the largest among GHGs, methane ($CH_4$) emission had the highest contribution to carbon footprint on rice production system when it was converted to carbon dioxide equivalent ($CO_2-eq.$) multiplied by the global warming potential (GWP). Main source of $CO_2$ emission in the rice farming system without agricultural chemicals was combustion of fossil fuels used by agricultural machinery. Most of the $CH_4$ was emitted during rice cultivation practice and its major emission factor was flooded paddy field in anaerobic condition. Also, most of the $N_2O$ was emitted from rice cultivation process. Major sources of the $N_2O$ emission was application of fertilizer such as compound fertilizer. As a result of sensitivity analysis in energy consumption, diesel had the highest sensitivity among the energy inputs. With the reduction of diesel consumption by 10%, it was estimated that $CO_2$ potential reduction was about 2.0%. With reducing application rate of compound fertilizer by 10%, the potential reduction was calculated that $CO_2$ and $N_2O$ could be reduced by 0.5% and 0.9%, respectively. At the condition of 10% reduction of silicate and compost, $CO_2$ and $CH_4$ could be reduced by 1.5% and 1.6%, respectively. With 8 days more drainage than the ordinary practice, $CH_4$ emission could be reduced by about 4.5%. Drainage and diesel consumption were the main sources having the largest effect on the GHG reduction at the farming system without agricultural chemicals. Based on the above results, we suggest that no-tillage and midsummer drainage could be a method to decrease GHG emissions from rice production system.

• Polymer(Korea)
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• v.29 no.2
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• pp.177-182
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• 2005

Montmorillonite (MMT) modified with siloxane diamine was reacted with a reactant obtained from 4,4'-diphenyl methane diisocyanate (MDI) and polyester type polyol, $Nippollan4010(\bar{M}_n2000)$. Finally, polyurethane (PU)/MMT composites were prepared by using 1,4-butane diol as a chain extender in $25\;wt\%$ solution of N,N-dimethyl acetamide (DMAc). It was expected that these nanocomposites had superior exfoliation property to that of MMT dispersed polyurethanes produced by simple mixing due to insertion of siloxane main chain to the silicate interlayer of MMT. Extent of reaction and formation of final products were analysed by using FT-IR spectroscopy. Dispersion into the PU and intercalation of MMT were identified by applying X-ray diffraction (XRD) and transmission electron microscopy (TEM). Tensile data were acquired by universal test machine (UTM). Thermal stability and variation of surface energy were characterized by thermal gravimetric analysis (TGA) method and measurement of contact angle on the synthesized composites, respectively. As the results the organo-MMT modified with siloxane diamine in the PU composites has an intercalated structure relatively well-expanded rather than a completely exfoliated structure. The tensile strengths and the moduli for the PU/organo-MMT composites were drastically enhanced in comparison to those of $PU/Na^+-MMT$ composites.

• Journal of Environmental Science International
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• v.23 no.8
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• pp.1429-1436
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• 2014

In this study, we investigated the effects of dietary supplementation (n = 40 pigs/treatment) with bamboo powder (0, 1, 2 and 3%) for 38 days. We evaluated growth performance, blood metabolites, and carcass characteristics of fattening pigs and gas emission and microbial populations in pig manure, to obtain data on pork producers for environmental management. We obtained the following results. First, supplementation with increasing amounts of bamboo powder had a significant (P < 0.05) effect on feed intake, feed efficiency, and glucose contents (except for initial and final body weight, weight gain, carcass characteristics, and blood urea nitrogen). In terms of blood metabolites, glucose and blood urea nitrogen tended to decrease with increasing amounts of bamboo powder. Second, the amounts of ammonia, methane, amine, hydrogen sulfide, and acetic acid were reduced by increasing amounts of bamboo powder when compared with the controls (P < 0.05). However, there were no significant differences in pH, propionic acid, iso-butyric acid, butyric acid, iso-valeric acid, and valeric acid among all treatments. The lowest gas emission was observed when 3% bamboo powder was used. Third, supplementation with increasing amounts of bamboo powder tended (P < 0.05) to increase the total number of bacteria, Lactobacillus spp., and yeast, but E. coli, Salmonella spp., and Shigella spp. were not detected in any treatment. In conclusion, the results of this study suggest that supplementation with bamboo powder was effective in reducing gas emission and inhibiting pathogen populations in pig manure by lowering the pH of the manure.

• Journal of the Korean Institute of Gas
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• v.5 no.2 s.14
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• pp.36-42
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• 2001

A leak of fuel gas in partially confined area creates a flammable atmosphere and give rise to an explosion, which is one of the most common accident in domestic. Observations from accident in domestic suggest that some explosions are caused by a quantify of fuel significantly less than lower explosion limit(LEL) amount required to fill the room, which is attributed to inhomogeneous mixing of leaked gas. The minimum amount of leaked gas for explosion is highly dependent on the mixing degree in the area. For lighter gas, such as methane, a high concentration tends to build up in the space from ceiling of room. But heavy gas, such as propane, a high concentration tends to build up in the space from bottom of room. This paper presents a method for analysing the explosion hazard in a room with very small amount of leaked gas. Based on explosion limit concentration, the gaussian distribution model is used to estimate the minimum amount of leak which yields a specified explosion pressure. The results demonstrate that catastrophic structural damage can be achieved with a volume of fuel gas which is less than 0.5 percent of the total enclosed volume in domestic. The method will help analyzing hazard to develop new safe device as well as investigating accident.

• Journal of the Korean Institute of Gas
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• v.14 no.3
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• pp.41-45
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• 2010

The physical properties of DME(Dimethyl Ether) are very similar to LPG and well-mixed. As cetane number of DME is similar to diesel fuel that can replace diesel fuel and alternative energy. DME is a clean energy source that can be manufactured from various raw materials such as natural gas, CBM(Coal Bed Methane) and biomass. DME has no carbon-carbon bond in its molecular structure and its combustion essentially generates no soot as well as no SOx. The development of DME process in KOGAS have 4 section. First, syngas section can be manufactured various syngas ratio. This completes the tri-reforming process for the synthesis gas ratio of approximately 4.0 to 1.0 range can be adjusted. Second, $CO_2$ is removed from the $CO_2$ removal section of about 92~99%, so the maximum concentration of $CO_2$ entering the DME synthesis reactor should not exceed 8%. Third, in the DME synthesis section, if the temperature of DME reactor increases, the activity of DME catalyst increased. but for the long-term activity is desirable to maintain the proper temperature. Finally, the purity of DME in the DME purification section is over 99.6%.