• Tunnel and Underground Space
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• v.22 no.3
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• pp.163-172
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• 2012

As more diesel engines have been employed in underground limestone mines with large cross section, underground space environment is worsened by diesel exhausts and heat flow. This paper aims for the ultimate goal to optimize the work place environment through assuring the optimal required ventilation rate based on the analysis of the airflow, diesel exhaust gas concentrations and the effects of mechanization and deepening working face on temperature and humidity. Due to the insufficient capacity of the main exhaust fan and poor airway management, stagnant airflows were observed at various locations, while the flow direction was reversed instantly with passing diesel equipment and the flow reversal was also made by the seasonal variation of the outside surface weather. During the loading operation, CO concentration measurements were found to be frequently higher than the threshold limit of 50 ppm, and most of the $NO_2$ measurements during drilling and loading operations shows even more serious levels surpassing the permissible limit of 3 ppm. The actual ventilation quantity was considerably less than the required quantity estimated by the mine health and safety law, and this shortage problem was less serious in colder winter showing more effectiveness of the natural ventilation.

• Korean Journal of Soil Science and Fertilizer
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• v.43 no.5
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• pp.716-721
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• 2010

LCA (Life Cycle Assessment) carried out to estimate carbon footprint and to establish of LCI (Life Cycle Inventory) database of rice production system. The results of collecting data for establishing LCI D/B showed that organic fertilizer and chemical fertilizer input to 4.29E-01 kg $kg^{-1}$ rice and 2.30E-01 kg $kg^{-1}$ rice for rice cultivation. It was the highest value among input for rice cultivation. And direct field emission was 3.23E-02 kg $kg^{-1}$ during rice cropping. The results of LCI analysis focussed on greenhouse gas (GHG) was showed that carbon footprint was 8.70E-01 kg $CO_2$-eq. $kg^{-1}$ rice. Especially for 80% of $CO_2$ in the GHG and 7.02E-01 kg of its $CO_2$-eq. $kg^{-1}$ rice. Of the GHG emission $CH_4$, and $N_2O$ were estimated to be 13% and 5%, respectively. With LCIA (Life Cycle Impact Assessment) for rice cultivation system, it was observed that fertilizer process might be contributed to approximately 80% of GWP (global warming potential).

• Journal of the Korean Wood Science and Technology
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• v.34 no.6
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• pp.36-43
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• 2006

Using fluidized bed type fast pyrolysis system (capacity 400 g/h) bio-oils were produced from beech (Fagus sylvatica) and softwood mixture (spruce and larch, 50:50). The pyrolysis was performed for 1~2 s at the temperature of $470{\pm}5^{\circ}C$. Pyrolysis products consisted of liquid form of bio-oil, char and gases. In beech wood bio-oil was formed to ca. 60% based on dry biomass weight and the yield of bio-oil was 49% in soft wood mixture. The moisture contents in both bio-oils were ranged between 17% and 22% and the bio-oil's density was measured to $1.2kg/{\ell}$. Bio-oils were composed of 45% carbon, 47% oxygen, 7% hydrogen and lower than 1% nitrogen,which was very similar to those of original biomass. In comparison with oils from fossil resources, oxygen content was very high in bio-oils, while no sulfur was found. More than 90 low molecular weight components, classified to aromatic and non aromatic compounds, were identified in bio-oils by gas chromatographic analysis, which amounted to 31~33% based on the dry weight of bio-oils.

• Journal of the Korean Wood Science and Technology
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• v.45 no.3
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• pp.278-287
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• 2017

In this study, lignin was efficiently degraded via two-step catalytic cracking process and lignin-oil, char, and gas was produced as lignin degraded products. Three kinds of catalysts (MgO, CaO, and Pt/C) were used in first catalytic cracking step and the highest lignin-oil yield (76.2 wt%) was obtained in Pt/C catalyst with the smallest char formation (4.1 wt%). GC-MS/FID analysis revealed that 18 kinds of monomeric phenols existed in lignin-oil and sum of them was the highest in Pt/C condition (97.8 mg/g lignin). Meanwhile, relatively lower yield of monomeric phenols was produced in MgO and CaO condition because of their absorption on catalysts. Lignin-oil produced over Pt/C was introduced to second catalytic cracking process with porous Pd/activated carbon aerogel catalyst. From this process, four kinds of monomeric phenols such as 4-ethylguaiacol, 4-propylguaiacol, 4-ethylsyringol, 4-propylsyringol were selectively produced at 0.89 - 1.82 wt% level.

• Journal of Korea Foresty Energy
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• v.19 no.2
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• pp.86-92
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• 2000

The liquefactions of $\alpha$-cellulose(Sigma Chemical, C-8002, 47H0383) was prepared in the presence of phenol using sulfuric acid as a catalyst under $N_2$ gas protection at $180^{\circ}C$ for 60minutes to examine its components. The ratio of $\alpha$-cellulose to phenol was 1: 6.2(w/w), and that to sulfuric acid was 1: 0.05(g/$m\ell$). The yields of liquefaction were calculated after the liquefied mixtures were passed through 1G4 glass filter. The luquefied product of $\alpha$-cellulose was analyzed using GC-MS Spectormeter. The 12 compounds identified by GC-MS Spectrometer, of which peak area covers 54% as 2,4-dimethyl phenol, p-isopropyl phenol, 1-ethyl-3,5-dimethyl benzene, o-isopropyl phenol, (E)-2,4\` dihydroxy-stilbene, 2,2\`-methylene-bisphenol, 4,4\`-methylenebisphenol, 3-methyl-2-hydroxyphenyl-(E)-2-hydroxyl-4\`-methoxy-stilbene, 1-phyenyl-1-(4\`hydroxyphenyl)methanol phenol derivatives. From this results, the reaction pathways of the liquefaction of cellulose were proposed through electrophilic substitution reaction. Phenol as a solvent might react with the reaction intermediates as well in the cellulose liquefaction.

• The Korean Journal of Pesticide Science
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• v.14 no.4
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• pp.361-370
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• 2010

Considering the efficiencies of the preparation process at each stage obtained in previous studies, the analytical determination method was established for multi-pesticide residues in soils. It consist of the acetone-extraction, the dichloromethane-partition, the Florisil or silica-gel chromatography and the gas chromatography analysis equipped with the electron capture detector and the nitrogen-phosphorus detector. In the soil recovery test by Florisil clean-up system, the number of pesticides recovered in the range of 70~120% and showed less than 20% of RSD were 165 pesticides for paddy soil, 169 pesticides for upland soil and 159 pesticides in both soils through the tested 183 pesticides. And in the soil recovery test by silica-gel system, the number of pesticides recovered in the range of 70~120% and showed less than 20% of RSD were 154 pesticides for paddy soil, 145 pesticides for upland soil, and 134 pesticides in both soils.

• Polymer(Korea)
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• v.34 no.6
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• pp.540-546
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• 2010

In this manuscript, in order to reduce methanol permeability and, at the same time, to increase proton conductivity THS-PSA containing silica compound, responsible for methanol permeability reduction, and sulfonic acid, responsible for proton conductivity enhancement, was applied onto PVA/PSSA-MA membranes. And in order to improve durability, the resulting membranes, PVA/PSSAMA/THS-PSA, were exposed to 500ppm F2 gas at varying reaction times. The surface-fluorinated membranes were characterized through the measurement of contact angles, thermo-gravimetric analysis, and X-ray photoelectron spectroscopy to observe the physico-chemical changes. For the evaluation of the electro-chemical changes in the resulting membranes, its water contents, ion exchange capacity, proton conductivity, and methanol permeability were measured and then compared with the commercial membrane, Nafion 115. Finally, the membran electrode assembly(MEA) was prepared and the cell voltage against the current density was measured. As fluorination time increased, the contents of F2 increased up to maximum 4.3% and to depth of 50 nm. At 60 min of fluorination, the proton conductivity was 0.036 S/cm, larger than Nafion 115 at 0.024 S/cm, and the methanol permeability was $9.26E-08cm^2/s$, less than Nafion 115 at $1.17E-06cm^2/s$.

• Korean Journal of Environment and Ecology
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• v.25 no.1
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• pp.91-101
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• 2011

The purpose of this study is to demonstrate the positive effects of artificial ground greening on the reduction of carbon dioxide ($CO_2$) which can help improve ecological functions in cities and mitigation of climate change, through quantifying $CO_2$ uptake and evapotranspiration by the process of photosynthesis of some plants. Experiment of $CO_2$ uptake and evapotranspiration was conducted by measurement of $CO_2$ exchange rate using the infrared gas analyzer, for 7 month, growing season from May to November 2009, 2 times a month. The result was as follows; The $CO_2$ uptake quantity per $cm^2$ of Chrysanthemum zawadskii was the highest rate at $21.47{\times}10^{-6}g/cm^2/s$ and Poa pratensis was $16.20g{\times}10^{-6}g/cm^2/s$. The stronger was light of intensity, the higher were $CO_2$ uptake rate of most plants. In quantity of evapotranspiration, Poa pratensis was the highest rate at $8.75{\times}10^{-5}g/cm^2/s$ and Aquilegia buergariana was $8.66{\times}10^{-5}g/cm^2/s$. From this study, it is confirmed that artificial ground greening has capacity of absorption $CO_2$ and effects on improving urban microclimate.

• The Korean Journal of Mycology
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• v.27 no.6 s.93
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• pp.424-429
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• 1999

This study was conducted to investigate the characteristics of polysaccharides isolated from the fruit body and cultured mycelia of Phellinus linteus IY001. All fractions were extracted by hot water, followed by ethanol precipitation (F-THE and M-HE) or ultrafiltration (M-HU) (F-TH, F-THE; fruit body, M-HE, M-HU; cultured mycelia). Among these fractions, F-TH fraction was obtained at the highest yields of 6.83% and yield of F-THE was at the level 2.79%. The carbohydrates of these fractions was found to be a heteroglucan composed of glucose, galactose, mannose, fructose, ribose and xylose by analysis of gas chromatography. The total carbohydrate contents of M-HE and M-HU fractions were 99.2%, and 86.0% respectively. The glucose content of M-HE, M-HU and F-THE ranged from 54 to 84.8% of the total monosaccharide. Amino acid pattern showed that all fractions contained a large amount of aspartic acid, glycine, glutamic acid, alanine. Serine and threonine were found to be involved in the linkage, O-linked type. These fractions, except F. TH, contained polysaccharides with the molecular weights of 12 kD and showed the characteristics of IR absorption for ${\beta}-glucosides$ at $890\;cm^{-1}$.

• Journal of the Mineralogical Society of Korea
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• v.18 no.4 s.46
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• pp.313-323
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• 2005

XRD, XRF, EPMA, FT-IR, and SEM-CL studies were carried out in order to characterize gemological features of corundum from Tanzania. Fluorescence reaction of the Tanzanian corundum to short and long wave ultraviolet rays was weakly detected. Inclusions in Tanzanian corundum are divided into five types, Type I is fluid-rich inclusion, Type II is gas-rich inclusion, Type III is liquid $CO_{2}$ inclusion, Type IV is solid-rich inclusion, and Type V is a mixture of fluid and solid inclusion and daughter minerals. SEM-CL images show twin structure with growth texture, microphenocryst of spinel solid inclusions, massive and growth texture. Ruby and sapphire from Tanzania are distinctly distinguished by concentrations of Fe and Cr, and plotted in the particular field at $Al_{2}O_{3}/100-Cr_{2}O_{3}-Fe_{2}O_{3}$ diagram. According to FT-IR analysis, all corundum specimens from Tanzania showed the similar patterns, and absorption peaks of $455.09\~459.23\;cm^{-1},\;603.15\~611.71\;cm^{-1},\;1509.00\~1655.05\;cm^{-1}\;and\;3436.41\~3468.87\;cm^{-1}$. These distinctive characteristics mentioned above can be used to identify the locality and source of corundum stones from Tanzania.