• Journal of Korean Society of Environmental Engineers
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• v.35 no.8
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• pp.586-591
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• 2013

This experiment was performed to enhance $CH_4$ purity of landfill gas by applying gas separator membrane for purified nitrogen gas production. 1:6 area ratios of $1^{st}$ to $2^{nd}$ membrane module was suitable for $CH_4$ recovery. After separation membrane system was installed, 249 tries were performed. Average permeability for $CH_4$ was 28.4% and for $CO_2$ was 94.3%. This can explain nitrogen gas separator membrane can be applied to collect $CH_4$ from LFG. However, nitrogen permeability only reached up to 16.5%. Therefore, the final purified landfill gas concentration was rounded up to 69.7% for $CH_4$, 4.3% for $CO_2$ and 26.0% for $N_2$. For the high degree of $CH_4$ purity, $N_2$ should be kept at least under 2.0% by controlling air inflow to landfill.

• Polymer(Korea)
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• v.32 no.3
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• pp.239-245
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• 2008

Block copolymers of the general formula $[(-CO-R'-CO-HN-Ar-NH-CO-R'-CO)_xNH(CH_2)_3-(Me_2SiO)_y(CH_2)_3NH_2]_n$, [n=18.00 to 1175.0] where $R'=CH_2CH(CH_2GeCl_3)$;$CH_2CHGeCl_3CH_2$; and $Ar=-C_6H_4$;$-(o.CH_3C_6H_4)_2$;$-o.CH_3OC_6H_4)_2$;$-(o.CH_3C_6H_4)$ were prepared by a polycondensation reaction of polyamide containing a pendant trichlorogermyl group and terminal acid chloride $Cl(-CO-R'-CO-NH-Ar-NH-CO-R'-CO-)_xCl$ with aminopropyl-terminated polydimethylsiloxane $H_2N(CH_2)_3(Me_2SiO)_y-(CH_2)_3NH_2]$, (PDMS). These polymers were characterized by elemental analysis, $T_g$, FT-IR, $^1H$-NMR, solid state $^{13}C$-NMR, and molecular weight determination. The thermal stability of these copolymers was examined using thermal analysis techniques, such as TGA and DSC. Their molecular weights as determined by laser light scattering technique ranged $5.13{\times}10^5$ to $331{\times}10^5\;g/mol$. These polymers display their $T_g$ in the range of 337 to $393^{\circ}C$ with an average decomposition temperature at $582^{\circ}C$.

• Korean Chemical Engineering Research
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• v.50 no.5
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• pp.802-807
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• 2012

The autothermal reforming of methane to syngas has been carried out in a reactor charged with both a Ni (15 wt%)-Ru (1 wt%)/$Al_2O_3$-MgO metallic monolith catalyst and an electrically-heated convertor (EHC). The standalone type reactor has a start-up time of less than 2 min with the reactant gas of $700^{\circ}C$ fed to the autothermal reactor. The $O_2/CH_4$ and $H_2O/CH_4$ ratio governed the methane conversion and temperature profile of reactor. The reactor temperature increased as the reaction shifted from endothermic to exothermic reaction with decreasing $H_2O/CH_4$ ratio. Also the amount of $CO_2$ in the products increases with increasing $H_2O/CH_4$ ratio due to water gas shift reaction. The 97% of $CH_4$ conversion was obtained and the reactor temperature was maintained $600^{\circ}C$ at the condition of $GHSV=10,000\;h^{-1}$ and feed ratio ($H_2O/CH_4=0.6$ and $O_2/CH_4=0.5$). In this condition, the maximum flow rate of the syngas generated from the reactor charged with 170 cc of the metallic monolith catalyst is $0.94\;Nm^3/h$.

• Asian-Australasian Journal of Animal Sciences
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• v.25 no.10
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• pp.1364-1373
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• 2012

Four crossbred (75% Holstein Friesian) lactating dairy cows, with an average live weight of $418{\pm}5$ kg and $36{\pm}10$ d in milk were randomly assigned according to a $2{\times}2$ factorial arrangement in a $4{\times}4$ Latin square design to evaluate the effects of cassava hay (CH) and rice bran oil (RBO) on feed intake, nutrient digestibility, ruminal fermentation, milk yield, and milk composition. Factor A was non-supplementation or supplementation with CH in the concentrate. Factor B was supplementation with RBO at 0% or 4% in the concentrate mixture. The four dietary treatments were (T1) control (Concentrate with non-CH plus 0% RBO; C), (T2) Concentrate with CH plus 0% RBO (CH), (T3) Concentrate with non-CH plus 4% RBO (RBO), and (T4) Concentrate with CH plus 4% RBO (CHRBO). The cows were offered concentrate, at a ratio of concentrate to milk production of 1:2, and urea-lime treated rice straw was fed ad libitum. Urea-lime treated rice straw involved 2.5 g urea and 2.5 g $Ca(OH)_2$ (purchased as hydrated lime) in 100 ml water, the relevant volume of solution was sprayed onto a 100 g air-dry (91% DM) straw, and then covering the stack with a plastic sheet for a minimum of 10 d before feeding directly to animals. The CH based concentrate resulted in significantly higher roughage intake and total DM intake expressed as a percentage of BW (p<0.05). Ruminal pH, $NH_3$-N, BUN and total VFA did not differ among treatments, while RBO supplementation increased propionate, but decreased acetate concentration (p<0.05). Furthermore, the population of total ruminal bacteria was significantly lower on the RBO diet (p<0.05). In contrast, the total ruminal bacteria and cellulolytic bacteria on the CH diet were higher than on the other treatments. Supplementation with CH increased (p<0.05) F. succinogens and R. flavefaciens populations, whereas the populations of B. fibrisolvens and M. elsdenii were increased on the RBO diet. In addition, supplementation with CH and RBO had no effect on milk production and composition in dairy cows, while fatty acid composition of milk was influenced by RBO supplementation, and resulted in significantly lower (p<0.05) concentrations of both short-chain and medium-chain FA, and increased (p<0.05) the proportion of long-chain FA in milk fat, as well as significantly increased cis-9, trans-11 CLA and total CLA. In conclusion, RBO or CH exhibited specific effects on DMI, rumen fermentation, microbial population, milk yield and composition in lactating dairy cows, which were not interactions between CH and RBO in the diets. Feeding lactating dairy cows with RBO could improve fatty acid in milk fat by increasing cis-9, trans-11 CLA.

• Journal of Korean Society for Atmospheric Environment
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• v.29 no.6
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• pp.789-800
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• 2013

$N_2O$ and $CH_4$, Greenhouse gas emission, Forest soil, Closed chamber technique, Soil uptake $N_2O$ and $CH_4$ are important greenhouse gases (GHG) along with $CO_2$ influencing greatly on climate change. Their soil emission rates are highly affected by bio-geo-chemical processes in C and N through the land-atmosphere interface. The forest ecosystems are generally considered to be net emission for $N_2O$; however, net sinks for $CH_4$ by soil uptake. Soil $N_2O$ and $CH_4$ emissions were measured at Mt. Taewha in Gwangju, Kyeonggi, Korea. Closed chamber technique was used for surface gas emissions from forest soil during period from May to October 2012. Gas emission measurement was conducted mostly on daytime (from 09:00 to 18:00 LST) during field experiment period (total 25 days). The gas samples collected from chamber for $N_2O$ and $CH_4$ were analyzed by gas chromatography. Soil parameters were also measured at the sampling plot. GHG averages emissions during the experimental period were $3.11{\pm}16.26{\mu}g m^{-2}hr^{-1}$ for $N_2O$, $-1.36{\pm}11.3{\mu}gm^{-2}hr^{-1}$ for $CH_4$, respectively. The results indicated that forest soil acted as a source of $N_2O$, while it acted like a sink of $CH_4$ on average. On monthly base, means of $N_2O$ and $CH_4$ flux during May (spring) were $8.38{\pm}48.7{\mu}gm^{-2}hr^{-1}$, and $-3.21{\pm}31.39{\mu}gm^{-2}hr^{-1}$, respectively. During August (summer) both GHG emissions were found to be positive (averages of $2.45{\pm}20.11{\mu}gm^{-2}hr^{-1}$ for $N_2O$ and $1.36{\pm}9.09{\mu}gm^{-2}hr^{-1}$ for $CH_4$); which they were generally released from soil. During September (fall) $N_2O$ and $CH_4$ soil uptakes were observed and their means were $-1.35{\pm}12.78{\mu}gm^{-2}hr^{-1}$ and $-2.56{\pm}11.73{\mu}gm^{-2}hr^{-1}$, respectively. $N_2O$ emission was relatively higher in spring rather than other seasons. This could be due to dry soil condition during spring experimental period. It seems that soil moisture and temperature mostly influence gas production and consumption, and then emission rate in subsoil environment. Other soil parameters like soil pH and chemical composition were also discussed with respect to GHG emissions.

• International Journal of Oral Biology
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• v.35 no.4
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• pp.169-175
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• 2010

Cholinesterase (ChE) is one of the most ubiquitous enzymes and in addition to its well characterized catalytic function, the morphogenetic involvement of ChE has also been demonstrated in neuronal tissues and in non-neuronal tissues such as bone and cartilage. We have previously reported that during mouse tooth development, acetylcholinesterase (AChE) activity is dynamically localized in the dental epithelium and its derivatives whereas butyrylcholinesterase (BuChE) activity is localized in the dental follicles. To test the functional conservation of ChE in tooth morphogenesis among different species, we performed cholinesterase histochemistry following the use of specific inhibitors of developing molar and incisors in the hamster from embryonic day 11 (E11) to postnatal day 1 (P1). In the developing molar in hamster, the localization of ChE activity was found to be very similar to that of the mouse. At the bud stage, no ChE activity was found in the tooth buds, but was first detectable in the dental epithelium and dental follicles at the cap and bell stages. AChE activity was found to be principally localized in the dental epithelium whereas BuChE activity was observed in the dental follicle. In contrast to the ChE activity in the molars, BuChE activity was specifically observed in the secretory ameloblasts of the incisors, whilst no AChE activity was found in the dental epithelium of incisors. The subtype and localization of ChE activity in the dental epithelium of the incisor thus differed from those of the molar in hamster. In addition, these patterns also differed from the ChE activity in the mouse incisor. These results strongly suggest that ChE may play roles in the differentiation of the dental epithelium and dental follicle in hamster, and that morphogenetic subtypes of ChE may be variable among species and tooth types.

• Journal of information and communication convergence engineering
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• v.6 no.1
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• pp.38-42
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• 2008

Highly sensitive and mechanically stable gas sensors have been fabricated using the microfabrication and micromachining techniques. The sensing materials used to detect the offensive $CH_3SH$ and $(CH_3)_3N$ gases are 1 wt% Pd-doped $SnO_2$ and 6 wt% $Al_2O_3$-doped ZnO, respectively. The optimum operating temperatures of the devices are $250^{\circ}C$ and $350^{\circ}C$ for $CH_3SH$ and $(CH_3)_3N$, respectively and the corresponding heater power is, respectively, about 55mW and 85mW. Excellent thermal insulation is achieved by the use of a double-layer membrane: i.e. $0.2{\mu}m$-thick silicon nitride and $1.4{\mu}m$-thick phosphosilicate glass. The sensors are mechanically stable enough to endure the heat cycles between room temperature and $350^{\circ}C$, at least for 30 days.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.8
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• pp.1376-1382
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• 2016

The discharge characteristics of inductively coupled $Ar/CH_4$ plasma were investigated by fluid simulation. The inductively coupled plasma source driven by 13.56 Mhz was prepared. Properties of $Ar/CH_4$ plasma source are investigated by fluid simulation including Navier-Stokes equations. The schematics diagram of inductively coupled plasma was designed as the two dimensional axial symmetry structure. Sixty six kinds of chemical reactions were used in plasma simulation. And the Lennard Jones parameter and the ion mobility for each ion were used in the calculations. Velocity magnitude, dynamic viscosity and kinetic viscosity were investigated by using the fluid equations. $Ar/CH_4$ plasma simulation results showed that the number of hydrocarbon radical is lowest at the vicinity of gas feeding line due to high flow velocity. When the input power density was supplied as $0.07W/cm^3$, CH radical density qualitatively follows the electron density distribution. On the other hand, central region of the chamber become deficient in CH3 radical due to high dissociation rate accompanied with high electron density.

• Korean Journal of Soil Science and Fertilizer
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• v.45 no.5
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• pp.853-860
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• 2012

To estimate potential use of fly ash in reducing $CH_4$ and $CO_2$ emission from soil, $CH_4$ and $CO_2$ fluxes from a paddy soil mixed with fly ash at different rate (w/w; 0, 5, and 10%) in the presence and absence of fertilizer N ($(NH_4)_2SO_4$) addition were investigated in a laboratory incubation for 60 days under changing water regime from wetting to drying via transition. The mean $CH_4$ flux during the entire incubation period ranged from 0.59 to $1.68mg\;CH_4\;m^{-2}day^{-1}$ with a lower rate in the soil treated with N fertilizer due to suppression of $CH_4$ production by $SO_4^{2-}$ that acts as an electron acceptor, leading to decreases in electron availability for methanogen. Fly ash application reduced $CH_4$ flux by 37.5 and 33.0% in soils without and with N addition, respectively, probably due to retardation of $CH_4$ diffusion through soil pores by addition of fine-textured fly ash. In addition, as fly ash has a potential for $CO_2$ removal via carbonation (formation of carbonate precipitates) that decreases $CO_2$ availability that is a substrate for $CO_2$ reduction reaction (one of $CH_4$ generation pathways) is likely to be another mechanisms of $CH_4$ flux reduction by fly ash. Meanwhile, the mean $CO_2$ flux during the entire incubation period was between 0.64 and $0.90g\;CO_2\;m^{-2}day^{-1}$, and that of N treated soil was lower than that without N addition. Because N addition is likely to increase soil respiration, it is not straightforward to explain the results. However, it may be possible that our experiment did not account for the substantial amount of $CO_2$ produced by heterotrophs that were activated by N addition in earlier period than the measurement was initiated. Fly ash application also lowered $CO_2$ flux by up to 20% in the soil mixed with fly ash at 10% through $CO_2$ removal by the carbonation. At the whole picture, fly ash application at 10% decreased global warming potential of emitted $CH_4$ and $CO_2$ by about 20%. Therefore, our results suggest that fly ash application can be a soil management practice to reduce green house gas emission from paddy soils. Further studies under field conditions with rice cultivation are necessary to verify our findings.

• Journal of The Korean Astronomical Society
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• v.38 no.2
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• pp.215-218
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• 2005

An atlas of high resolution (${\lambda}/{\Delta}{\lambda}$=45,000) profiles of interstellar atomic lines of K I (7665, 7699 ${\AA}$), Na I (D 1, D2), Ca II (H, K), Ca I (4227 ${\AA}$), molecular structures of CH, CH+, CN and the major diffuse interstellar bands at 5780 and 5797 ${\AA}$ based on ${\~}$300 echelle spectra of ${\~}$200 OB stars is presented. Relationships between the reddenings, distances and equivalent widths of NaI, CaII, KI, CH, CH+, CN and diffuse bands are discussed. The equivalent width of K I (7699 ${\AA}$) as well as of CH4300 ${\AA}$ / correlate very tightly with E(B- V) in contrast to the features of neutral sodium, ionized calcium and the molecular ion CH+. The equivalent widths of the Hand K lines of Call grow with distance at a rate ${\~}$250m${\AA}$ per 1 kpc. A similar relation for NaI is much less tight. The strengths of neutral potassium lines, molecular features and diffuse interstellar bands do not correlate practically with distance. These facts suggest that ionized calcium fills the interstellar space quite homogeneously while the other carriers mentioned above, especially K I, CH and these of diffuse bands occupy more and more compact volumes, also filled with dust grains. Apparently the carriers of narrow diffuse bands are spatially correlated with simple molecules and dust grains - all abundant in the so-called 'zeta' type clouds. The same environment seems to be hostile to the carriers of broad diffuse interstellar bands (DIEs) (like 5780 or 6284) and -to a certain extent - also to CaII, NaI and CH+.