• Resources Recycling
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• v.31 no.6
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• pp.18-24
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• 2022

Dry reduction using natural gas was proposed to recover tin from waste tin oxide generated in a tin bath that was used for controlling the smoothness of architectural glass during production, and the reduction behavior was investigated. The utilized vertical natural gas dry reduction system is capable to process 4 L or 20 kg depending on input raw materials. The system was established by applying the upper intake and lower discharge method. The recovery rate was 97.2% at 800 ℃ and 4 sccm flow rate and increased with the amount of input gas. Hydrogen accounted for 23% of the discharge gas, showing a 16.6% hydrogen conversion rate. The reaction behavior of tin recovered via natural gas reduction provides basic data on the new waste resource reduction/recovery technology.

• Proceedings of the KSME Conference
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• 2000.04b
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• pp.949-955
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• 2000

Numerical study with detailed chemistry has been conducted to investigate the NOx formation and structure in $CH_4/Air-CO_2$ counterflow diffusion flames. The importance of radiation effect is identified and the role of $CO_2$ addition is addressed to thermal and chemical reaction effects, which can be precisely specified through the introduction of an imaginary species. Also NO separation technique is utilized to distinguish the contribution of thermal and prompt NO formation mechanisms. The results are as follows : The radiation effect is dominant at low strain rates and it is intensified by $CO_2$ addition. Thermal effect mainly contributes to the changes in flame structure and the amount of NO formation but the chemical reaction effect also cannot be neglected. It is noted that flame structure is changed considerably due to the addition of $CO_2$ in such a manner that the path of methane oxidation prefers to take $CH_4 {\rightarrow}CH_3{\rightarrow}C_2H_6{\rightarrow}C_2H_5$ instead of $CH_4 {\rightarrow}CH_3{\rightarrow}CH_2{\rightarrow}CH$. At low strain rate(a=10) the reduction of thermal NO is dominant with respect to reduction rate, but that of prompt NO is dominant with respect to total amount.

• Journal of the Korean Society of Safety
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• v.35 no.6
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• pp.1-8
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• 2020

In recent years, hydrogen has received much attention as an alternative energy source to fossil fuels. In order to ensure safety from the increasing number of hydrogen refueling stations, prevention methods have been required. In this regard, this study suggested an approach to reduce the risk of hydrogen refueling station by increasing Safety Integrity Level (SIL) for a Steam Methane Reformer (SMR) in On-Site Hydrogen Refueling Station. The worst scenario in the SMR was selected by HAZOP and the required SIL for the worst scenario was identified by LOPA. To verify the required SIL, the PFDavg.(1/RRF) of Safety Instrumented System (SIS) in SMR was calculated by using realistic failure rate data of SIS. Next, several conditions were tested by varying the sensor redundancy and proof test interval reduction and their effects on risk reduction factor were investigated. Consequently, an improved condition, which were the redundancy of two-out-of-three and the proof test interval of twelve months, achieved the tolerable risk resulting in the magnitude of risk reduction factor ten times greater than that of the baseline condition.

• Journal of the Korean Institute of Gas
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• v.19 no.3
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• pp.9-17
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• 2015

Almost all of the natural gas consumed in South Korea is compressed into very high pressure for the transportation through the underground pipelines, then reduced in pressure regulation stations before delivery to the consumer. For pressure reduction, expansion valves have been used due to the simple and effective installation, but recover none of the energy in the gas during compression. Hence, turbo-expanders are proposed instead of the valves to accomplish the same pressure letdown function and recover some of the compression energy in the form of shaft work converting into electric powers. Here we have theoretically calculated the electric powers at the pressure reduction from 68.7 bar to 23 bar (which are the average values taken at the inlet and outlet points of the expansion valve in medium-pressure regulation stations) according to the inlet conditions of temperature and flow rate. The natural gas is considered as two cases of a pure methane and the mixture of hydrocarbons with a very small amount of nitrogen, and the Peng-Robinson equation of state is employed for the calculation of required thermodynamic properties. The electric energy is recovered as much as 1596 MW(methane) and 1567 MW(mixture) based on the total supply of natural gas in 2013.

• Korean Journal of Soil Science and Fertilizer
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• v.37 no.1
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• pp.46-53
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• 2004

In this study, we compared the levels of methylotrophic bacterial community diversity in the leaf, stem, grain, root and rhizosphere soil sainples of four rice cultivars collected from three regions of Korea. Thirty five pigmented and five non-pigmented isolates showing characteristic growth on methanul were obtained. When phylotypes were defined by performing numerical analysis of 42 characteristics, four distinct clusters were formed. While two clusters, I and IV diverged on the basis of nitrate and nitrite reduction, other two clusters, comprising only pink pigmented colonies, diverged on the basis of cellulase activity. Out of the two reference strains used in the analysis, Methyhbacterium extorquens AM1 diverged from all the clusters and M. fujisawaense KACC 10744 grouped under cluster III. All the isolates were positive for urease, oxidase, catalase and pectinase activity and negative for indole production, MR and VP test, $H_2S$ production, starch, and casein hydrolysis. No clusters were found to possess thermotolerant isolates, as no growth of the isolates was observed at $45^{\circ}C$. Two strains in cluster I were found to possess gelatin hydrolysis and methane utilizing properties respectively. Most of the isolates in all the four clusters utilized monosaccliarides, disaccharide and polyols as carbon source. Six isolates showed considerable nitrogenase activity ranging from 86.2 to $809.9nmol\;C_2H_4\;h^{-1}\;mg^{-1}$ protein.

• Journal of Korean Society of Environmental Engineers
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• v.28 no.10
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• pp.1074-1081
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• 2006

As common pollutants in surface and groundwater, nitrate nitrogen($NO_3-N$) and trichloroethylene(TCE) can be chemically and biologically reduced by zero valent iron(ZVI) and peat soil. In batch microcosm experiments, chemical reduction of TCE and nitrate was supported by hydrogen from ZVI. For biological degradation of TCE and denitrification peat soil was introduced. ZVI reduced TCE, while peat provided TCE sorption site and microbes performing biological degradation. Nitrate reduction was also achieved by hydrogen from ZVI. In addition, indirect evidence of denitrification was observed. More reduction of TCE and nitrate was achieved by ZVI+peat treatment however nitrated reduction was hindered in the presence of TCE in the system due to the competition for hydrogen. TCE reduction mechanism was more dependent on ZVI, while nitrate was peat-dependent. Hydrogen and methane concentration showed that peat had various anaerobic denitryfing and halorespiring bacteria.

• 한국신재생에너지학회:학술대회논문집
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• 2011.05a
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• pp.172-172
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• 2011

Anaerobic digestion(AD) has successfully been used for many applications that have conclusively demonstrated its ability to recycle biogenic wastes. AD has been successfully applied in industrial waste water treatment, stabilsation of sewage sludge, landfill management and recycling of biowaste and agricultural wastes as manure, energy crops. During AD, i.e. organic materials are decomposed by anaerobic forming bacteria and fina1ly converted to excellent fertilizer and biogas which is primarily composed of methane(CH4) and carbon dioxide(CO2) with smaller amounts of hydrogen sulfide(H2S) and ammonia(NH3), trace gases such as hydrogen(H2), nitrogen(N2), carbon monoxide(CO), oxygen(O2) and contain dust particles and siloxanes. The production and utilisation of biogas has several environmental advantages such as i)a renewable energy source, ii)reduction the release of methane to the atomsphere, iii)use as a substitute for fossil fuels. In utilisation of biogas, most of biogas produced from small scale plant e.g. farm-scale AD plant are used to provide as energy source for cooking and lighting, in most of the industrialised countries for energy recovery, environmental and safety reasons are used in combined heat and power(CHP) engines or as a supplement to natural. In particular, biogas to use as vehicle fuel or for grid injection there different biogas treatment steps are necessary, it is important to have a high energy content in biogas with biogas purification and upgrading. The energy content of biogas is in direct proportion to the methane content and by removing trace gases and carbon dioxide in the purification and upgrading process the energy content of biogas in increased. The process of purification and upgrading biogas generates new possibilities for its use since it can then replace natural gas, which is used extensively in many countries, However, those technologies add to the costs of biogas production. It is important to have an optimized purification and upgrading process in terms of low energy consumption and high efficiency giving high methane content in the upgraded gas. A number of technologies for purification and upgrading of biogas have been developed to use as a vehicle fuel or grid injection during the passed twenty years, and several technologies exist today and they are continually being improved. The biomethane which is produced from the purification and the upgrading process of biogas has gained increased attention due to rising oil and natural gas prices and increasing targets for renewable fuel quotes in many countries. New plants are continually being built and the number of biomethane plants was around 100 in 2009.

• Asian-Australasian Journal of Animal Sciences
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• v.10 no.1
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• pp.35-46
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• 1997

An experiment with growing bulls were conducted to determine the effect of supplementation of a straw (S) with 15% molasses and 3% urea as an intimate mix (UMS) on its dry matter (DM) intake and digestibility (DMD) and reduction of methane ($CH_4$) production from fermentation in vitro of the straw. In the next experiment, the feeding of the UMS was compared with that of the feeding of molasses and urea in meals (DS) or in lick blocks (DSUMB) as supplements to straw. The UMS feeding increased daily intake of straw DM ($89.5 g{\cdot}kgW^{-0.75}$, p < 0.01) and digestible crude protein (DCP 333 g, p < 0.001) and nitrogen (N) balances ($508mg{\cdot}kgW^{-0.75}{\cdot}d^{-1}$, p < 0.01) of the bulls than the feeding of 'S' ($65g{\cdot}kgW^{-0.75}$, 55 g and $8.0mg{\cdot}kgW^{-0.75}{\cdot}d^{-1}$, respectively). It also increased the digestibility of DM ($594g{\cdot}kg^{-1}$, p < 0.05), organic matter (OM, $641g{\cdot}kg^{-1}$, p < 0.05), CP ($619g{\cdot}kg^{-1}$, p < 0.001) and acid detergent fibre (ADF, 773, p < 0.05). The $CH_4$ emitted per g of DOM apparently fermented in the rumen (DOMR) was 91.0 ml in the 'S' and reduced (p < 0.05) to 61.6 ml in the UMS. The feeding of the UMS when compared with that of the DS or DSUMB also gave a higher straw intake (1.77% of live weight, LW, p <0.01) and ADF digestibility ($516g{\cdot}kg^{-1}$, p < 0.05) than the other diets (1.52% or 1.55% LW and 472 or $490g{\cdot}kg^{-1}$, respectively) in association with the increased microbial N yield in the rumen (14.1, 5.62 or $17.0g{\cdot}kg^{-1}$ DOMR, respectively, p < 0.05), daily LW gains (233, 125 or 93 g, respectively, p < 0.05) and feed conversion ratios of the diets (26.0, 56.1, or 57.6 g feed/g LW gain, p > 0.05, respectively). It can be concluded that molasses and urea feeding as an intimate mix with straw (UMS) increased its digestion and intake in association with a reduced methane emissions in the rumen. When compared with that of their feeding in meals or in lick blocks as supplements to straw the UMS gave the highest straw in take and digestion and live weight gains of growing bulls concurring the finding that the UMS system may be the best way of molasses and urea feeding to ruminants fed straws.

• Asian-Australasian Journal of Animal Sciences
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• v.19 no.3
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• pp.376-380
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• 2006

An experiment was conducted to study the effect of temperature and pH on in vitro nutrient degradability, volatile fatty acid profile and methane production. The fermenter used was the semi-continuous system, known as the rumen simulation technique (RUSITEC). Sixteen cylinders were used at one time with a volume of 800 ml, the dilution rate was set at 3.5%/hour, the infused buffer being McDougall's artificial saliva. Basal diet (9.6 g DM) used in RUSITEC consisted of (DM) 6.40 g Timothy hay, 1.86 g crushed corn and 1.34 g soybean meal. The food for the fermentation vessel was provided in nylon bags, which were gently agitated in the liquid phase. The experiment lasted for 17 d with all the samples taken during the last 5 d. Treatments were allocated at random to four vessels each and were (1) two temperature levels of $39^{\circ}C$ and $41^{\circ}C$ (2) two pH levels of 6.0 and 7.0. The total diet contained ($g\;kg^{-1}$ DM) 957 OM, 115 CP and $167MJ\;kg^{-1}$ (DM) GE. Although increase in temperature from $39^{\circ}C$ to $41^{\circ}C$ reduced degradation of major nutrients in vitro, it was non-significant. Interaction effect of temperature with pH also reflected a similar trend. However, pH showed a significant (p<0.05) negative effect on the degradability of all the nutrients in vitro. Altering the in vitro pH from 7 to 6 caused marked reduction in DMD from 60.2 to 41.8, CPD from 76.3 to 55.3 and GED from 55.3 to 35.1, respectively. Low pH (6) depressed total VFA production (61.9 vs. 34.9 mM) as well as acetate to propionate ratio in vitro (from 2.0 to 1.5) when compared to pH 7. Compared to pH 7, total gas production decreased from 1,841 ml to 1,148 ml at pH 6, $CO_2$ and $CH_4$ production also reduced from 639 to 260 ml and 138 to 45 ml, respectively. This study supported the premise that pH is one of the principal factors affecting the microbial production of volatile fatty acids and gas. Regulating the ruminal pH to increase bacterial activity may be one of the methods to optimize VFA production, reduce methane and, possibly, improve animal performance.

• Journal of the Korea Organic Resources Recycling Association
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• v.29 no.2
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• pp.5-14
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• 2021

As the implementation of carbon reduction measures would be monitored starting from 2023 in line with the Paris Agreement, it is crucial and urgent to control GHGs emitted from wastes contributing to 11% of methane emissions. Despite such importance and urgency, 93% of wastes are deposited in unsanitary landfills in developing countries, presenting challenges to methane management. Against the backdrop, landfill gas-to-energy projects have once again drawn attention for their economic substantiality secured through CDM projects while there has been much research actively carried out to estimate methane emissions and GHG reductions in landfills located in developing countries. Although a signifiant difference was found between estimations calculated based on research methodologies and actual results monitored through registered CDM projects, there has not been a study conducted on what is causing such a difference. Accordingly, the research team conducted an analysis of 18 LFG projects out of 46 that were registered as LFG CDM projects under the UNFCCC and has identified precipitation(28%), malfunction(22%), organic content(11%), amount of landfilled waste(11%) and temperature(11%) as key parameters causing the difference between the amount of methane captured and the amount of GHG reduced.