• Journal of the Korean GEO-environmental Society
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• v.15 no.9
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• pp.5-12
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• 2014

Anaerobic digestion was investigated for the stabilization of sludge, decrease of volatile solids, production of biogas for wastewater sludge. In this study, total solids and volatile solids, elemental analysis were conducted to determine characteristics of various types of sludges and investigate the feasibility of biogas production of Municipal Wastewater Sludge (MWS), Industrial Wastewater Sludge (IWS), mixed sludge (Mix), and Municipal Wastewater Sludg Cake (MWSC). Total solids, volatile solids, and C/N ratio were determined in the range of 11.2~20.6 %, 62.1~83.1 % of TS and 4.96~8.33 %. Using the biochemical methane potential (BMP test), mixed sludge and wastewater sludge finished the methane production within approximately 20 day and 16~17 day. Sludge cake finished within 10 day. Mixed sludge produced 395.5 mL $CH_4$ per g of Volatile Solid (VS) and resulted in the highest methane production. For carbon dioxide production, five sludges had similar value of accumulated carbon dioxide production except for sludge cake.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.61 no.4
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• pp.251-256
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• 2016

The increase in carbon stock and sustainability of crop production are the main challenges in agricultural fields relevant to climate change. Methane is the most important greenhouse gas emitted from paddy fields. This study was conducted to investigate the effects of tillage and cultivation methods on methane emissions in rice production in 2014 and 2015. Different combinations of tillage and cultivation were implemented, including conventional tillage-transplanting (T-T), tillage-wet hill seeding (T-W), minimum tillage-dry seeding (MT-D), and no-tillage-dry seeding (NT-D). The amount of methane emitted was the highest in T-T treatment. In MT-D and NT-D treatments, methane emissions were significantly decreased by 77%, compared with that in T-T treatment. Conversely, the soil total carbon (STC) content was higher in MT-D and NT-D plots than in tillage plots. In both years, methane emissions were highly correlated with the dry weight of rice ($R^2=0.62{\sim}0.96$), although the cumulative emissions during the rice growing period was higher in 2014 than in 2015. T-T treatment showed the highest $R^2$ (0.93) among the four treatments. Rice grain yields did not significantly differ with the tillage and cultivation methods used. These results suggest that NT-D practice in rice production could reduce the methane emissions and increase the STC content without loss in grain yield.

• Journal of the Korean Society of Food Science and Nutrition
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• v.36 no.10
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• pp.1241-1247
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• 2007

Contents of polyphenol compounds and the physiological activity of extracts from Grifola frondosa by water and methanol extraction were investigated to determine their functional effects. A functional beverage was developed using the extracts. The yield and phenolic compounds content of the water extracts were highest (49.2% and 327 mg/100 g, respectively), while for the methanol extraction method they were 28.7% and 130 mg/100 g, respectively. DPPH (1,1-diphenyl-2-picrylhydrazyl) radical scavenging activity was 76.3% for the water extract and 65.4% for methanol extract, whereas the superoxide dismutase (SOD)-like activity was low ($26.3{\sim}36.8%\;at\;1,000{\mu}g/mL$ concentration) Angiotensin converting enzyme (ACE) inhibitory effect of water extract (75.1%) was higher compared to the methanol extracts (41.2%). Tyrosinase inhibition activity was 42.5% for the water extracts and 31.8% for the methanol extracts at $1,000{\mu}g/mL$ concentration. The most acceptable formulation for G. frondosa beverage developed was 0.5% G. frondosa water extract, 8.0% oligosaccharide, 2.0% green tea extract, 2.0% jujube extract, 1.0% Solomon's seal extract, 0.01% vitamin C, and 2.0% apple extract. The final product had 9.8 Brix and color values of L, 35.2+1.1; a, 3.2+0.2; b, 13.6+0.3.

• Korean Journal of Organic Agriculture
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• v.29 no.2
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• pp.241-256
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• 2021

The current study was to evaluate the antioxidant activity of Phyllostachys bambusoides (PHB) as a feed additives and investigate whether its antioxidant activity could be helpful for increasing rumen fermentation characteristics and methane reduction. The antioxidant activity results showed that total polyphenols and flavonoids contents were 43.54 ± 8.68 mg CE/g and 17.13 ± 0.45 mg QE/g, respectively, and the IC₅₀ values for 1,1-diphenyl-2-prcrylhydrazyl (DPPH) and 2,2'-azino-bis (3- ethylbenzthiazoline-6- sulphonic acid) (ABTS) radical scavenging activity were 163.13 ± 19.25 ㎍/mL and 97.07 ± 4.46 ㎍/mL, respectively. Two heads of cannulated Hanwoo (450 ± 30 kg), consuming timothy hay and a commercial concentrate (60:40, w/w) twice daily (at 09:00 and 17:30) at 2% of body weight, with free access to water and a mineral block, were used as rumen fluid donors. An in vitro incubation experiment was performed after 6, 12, 24, 48, and 72 hr with PHB added at concentration of 2, 4, and 6% of timothy hay basis. Total gas emission decreased as the amount of PHB addition increased at 6 and 24 hr of incubation. However, PHB addition did not affect total volatile fatty acid production, and methane and carbon dioxide emission also decreased as the amount of addition increased at 48 hr of incubation. Therefore, PHB was expected to be used as methane reducing additives in the ruminants.

• The Korean Journal of Quaternary Research
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• v.25 no.2
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• pp.17-24
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• 2011

We investigated the variation of $CaCO_3$ contents in cores PC1 and PC2 recovered from the continental slope area of the Ulleung Basin in the East Sea. $CaCO_3$ contents of cores PC1 and PC2 varied between 0.6 and 17.2% and between 0.3 and 43.0%, respectively. $CaCO_3$ contents in the upper part of core PC1 corresponding to MIS 1 are less than 5%, whereas those in the lower part of MIS 2 are more than 10%. Such variation of $CaCO_3$ contents in core PC1 confirms the previous results of $CaCO_3$ studies in the East Sea. In core PC2, $CaCO_3$ contents of the upper part are similar to those of core PC1. However, $CaCO_3$ contents in the lower part of core PC2 are more than 40%. According to XRD operation and SEM examination, the high $CaCO_3$ contents in the lower part of core PC2 are more attributable to the authigenic carbonate minerals rather than the biogenic carbonate composition. Such abundant authigenic carbonate minerals are closely related to the dissociation of methan hydrates which were observed in the Ulleung Basin.

• 한국신재생에너지학회:학술대회논문집
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• 2010.06a
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• pp.116.2-116.2
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• 2010

석유의 고갈과 고유가 시대에 직면한 현재 전 세계적으로 매장량이 풍부하고 안정적으로 공급이 가능한 석탄 활용에 대한 관심이 급격히 증가하고 있다. 석탄의 활용 분야 중 석탄 가스화(Coal gasifier)에서 유도된 합성가스를 이용하여 합성천연가스(SNG) 생산을 할 수 있는 메탄화(Methanation) 공정에서는 대부분 Ni계열 촉매를 사용하고 있는데, 촉매를 설계하는 관점에서 담체(Support), 조촉매(Promoter), Ni의 함량 등과 같은 설계 변수에 따라 촉매의 활성과 함께 메탄 수율이 결정된다. 본 연구에서는 다양한 담체상에 Ni를 담지 하여 20bar 압력에서 SNG 반응에 높은 활성을 보일 수 있는 촉매를 확보하고자 실험을 수행하였으며, 그 결과 $NiO/SiO_2-Al_2O_3$ 촉매가 가장 우수한 활성을 보이는 것을 알 수 있었다. 또한 $NiO/SiO_2-Al_2O_3$ 상에 Cerium, Ferric oxide 조촉매를 첨가하여 SNG 반응 활성 평가를 수행하였다.

• The Korean Journal of Petroleum Geology
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• v.7 no.1_2 s.8
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• pp.35-40
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• 1999

Chemical and isotopic compositions of hydrocarbon gases were analyBed to characterize the properties of the shallow gases distributed in the southeastern part of the Ulleung Basin, offshore Korea. Sediments from the core were also analyzed to determine the characteristics and relationship to shallow gases. Hydrocarbon gases in the sediments consisted of methane (697.9-6054.4 ppm), ethane, propane, butane and hexane. The total carbon content of the sediments ranges from 1.84fe to $5.11{\%}$ and the total organic carbon content ranges from $0.29{\%} \;to\; 2.65{\%}$. High C/N ratio (>10) indicates that input of terrestrial organic matter was prevalent at the time of deposition. The methane content and stable isotopic data indicate that hydrocarbon gases from the sediments are identified to be thermogenic gas and mixture of both biogenic and thermal gases. Based on the Rock-Eval and carbon isotopic data, the level of thermal maturity of organic matter in the sediments $(Tmax<425^{\circ}C)$ is lower than that of gas. It suggests that thermal gases in the sediments migrated from the deeper sediments than the penetrated depth.

• Economic and Environmental Geology
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• v.55 no.3
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• pp.261-271
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• 2022

Six gas samples were collected from coal and coaly shale from core AA-1, which was acquired from the Asem-Asem Basin, southeast Kalimantan, Indonesia. These coalbed gas samples were analyzed for the molecular composition, carbon isotope (δ¹³C_CH4, δ¹³C_C2, and δ¹³C_CO2), hydrogen isotope (δD_CH4), hydrocarbon index (C_HC), and carbon dioxide-methane index (CDMI) to document their origin and methanogenic pathways. Core AA-1 successively consists of lower clastic sedimentary rocks (Sedimentary Unit-1, SU-1) containing coal and coaly shale, and upper limestone (Sedimentary Unit-2, SU-2), unconformably underlain by serpentinized basement interpreted as part of the Cretaceous Meratus subduction complex (MSC). The coal and coaly shale (SU-1) were deposited in a marshes nearby a small-scale river. Compositions of coalbed gases show that methane ranges from 87.35 to 95.29% and ethane ranges from 3.65 to 9.97%. Carbon isotope of coalbed methane (δ¹³C_CH4) ranges from -60.3 to -58.8‰, while hydrogen isotope (δD_CH4) ranges from -252.9 to -252.1‰. Carbon isotope of coalbed ethane (δ¹³C_C2) ranges from -32.8 to -31.2‰, carbon isotope of coalbed carbon dioxide (δ¹³C_CO2) ranges from -8.6 to -6.2‰. The coalbed CO₂ is interpreted to be an abiogenic origin based on a combination of δ¹³C_CO2 and CDMI and could have been transported from underlying CO₂ bearing MSC through faults. The methanogenic pathways of coalbed gases are interpreted to have originated from primary methyl-type fermentation and mixed with CO₂ reduction, affecting thermogenic non-marine coal-type gases based on analyses of isotopic ratios and various indexes.

• Journal of the Korean Ceramic Society
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• v.38 no.1
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• pp.34-38
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• 2001

Hot filament CVD 방법에서 가스압을 증가시키는 방법을 사용하여 nanocrystalline 다이아몬드 막을 합성하였다. 메탄-수소 혼합가스를 사용하고 메탄함량, 유량, 기판온도합성시간은 각각 4%, 100sccm, 110$0^{\circ}C$, 10시간으로 일정하게 유 였다. 합성 변수로서 가스압을 40 Torr에서 300 Torr 구간에서 변화시켰다. High-resolution SEM으로 막 표면의 형상을 관찰하고, TEM, XRD, micro-Raman spectroscopy를 사용하여 합성된 막의 구조 및 특성을 분석하였다. 합성된 다이아몬드 막은 압력이 높아짐에 따라 mocrocrystalline 다이아몬드 막에서 점진적으로 nanocrystalline 다이아몬드 막으로 변화해갔으며, 가스압에 다라 비다이아몬드 상의 량이 증가하였다. 증착속도는 microcrystalline 다이아몬드 막이 형성되는 구간에서는 압력에 따라 1.1~1.3 $\mu\textrm{m}$/h까지 증가하다가 nanocrystalline 다이아모느 막이 형성되는 구간에서는 압력에 따라 감소하였다. 감소하였다.

• Journal of the Korea Organic Resources Recycling Association
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• v.24 no.3
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• pp.75-82
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• 2016

Objective of this experiment was to predict the potential methane production with crop residues at different loading rates. Anaerobic digestion of barley and rapeseed straw substrates for biogas production was performed in Duran bottles at various biomass loading rates with crop residues. Through kinetic model of surface methodology, the methane production was fitted to a Gompertz equation. For the biogas production at mesophilic digestion with crop residues, it was observed that maximum yield was 37.2 and 28.0 mL/g at 6.8 and 7.5 days after digestion with 1% biomass loading rates of barley and rapeseed straws, respectively. For the methane content of mesophilic digestion, there were highest at 61.7% after 5.5 days and 75.0% after 3.4 days of digestion with barley and rapeseed straw on both 5% biomass loading rates, respectively. The maximum methane production potentials were 159.59 mL/g for 1% barley straw and 156.62 mL/g for 3% rapeseed straw at mesophilic digestion. Overall, it would be strongly recommended that biomass loading rate was an optimum rate at mesophilic digestion for using 1% barley and 3% rapeseed straws for feed stocks.