• Clean Technology
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• v.7 no.1
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• pp.13-25
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• 2001

With fast advancement of fine machineries and semiconductor industries in recent decades, the ultra-cleaning of organic chemicals, submicron particles from contaminated unit equipments and products such as silicon wafers becomes one of the most important steps for further advancement of such industries. To date, two kinds of ultra cleaning techniques are used; one is the wet-cleaning and the other is the dry cleaning. In case of wet cleaning, removal of organic contaminants and submicron particles is made by DIW with additives such as $H_2O_2$, $H_2SO_4$, HCl, $NH_4OH$ and HF, etc. While the wet cleaning method is most widely adopted for various occasions, it is inevitable to discharge significant amount of toxic waste waters in environment. Dry cleaning is an alternative method to mitigate environmental pollution of the wet cleaning with maintaining comparable degree of cleaning to the wet cleaning. Although there are various concept of dry cleaning have been devised, the dry cleaning with environmentally-benign solvent such as carbon dioxide proven to show high degree of cleaning from the contaminated porous surface as well as from the bare surface. Thus, special global attention has been placing on this technique since it has important advantages of simple process schemes and no environmentally concern, etc. Thus, this article critically reviews the state-of-the-art of the supercritical fluid drying with emphasis on the thermo-physical characteristics of the supercritical solvent, environmental gains compared to other dry cleaning methods, and the generic aspects of the basic design and processing engineering.

• Culinary science and hospitality research
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• v.13 no.1 s.32
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• pp.119-128
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• 2007

Volatile flavor compounds of sauces made from shrimps, crabs or lobsters were analyzed by the combination of canister system, gas chromatography(GC) and mass selective detector(MSD). Of 72 total volatile compounds from 4 kinds of sauces, 45 compounds were identified from shrimp sauce(SS). Ten alkanes, 5 ketones, 3 aldehydes were obtained from SS. Especially, 3-methyl-2-butanone, 2-pentanamine, isobutane, 3-methyl-2-butanol, carbon disulfide and dimethyl sulfide were predominant compounds in SS. In crab sauce(CS), there were 18 compounds identified, including 4 alcohols, 4 alkanes, 3 aldehydes, 2 ketones, acid and amine. 2-Methoxy ethanol, trimethyloxirane and 3-buten-1-ol were special volatile compounds in CC. Volatile compounds from lobster head sauce(LHS) or lobster shell sauce(LSS) were 16 or 18 kinds respectively. The major volatile compounds of LHS were formic acid, 1-propanethiol, $\beta$-pinene and allyl sulfide, and those of LSS were acids, pentane, 3-methyl-1-butanol and 2,4-dimethyl-3-pentanone. It was thought that the volatile compounds identified from sauces as well as shrimps, crabs or lobsters might come from wine, onions, bay leaves or celery used as minor ingredients.

• Journal of the Korean Society for Marine Environment & Energy
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• v.17 no.4
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• pp.268-273
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• 2014

Experiments on carbonization were conducted using fish offal generated from fish market for the purpose of resource recycling. Elemental composition of fish offal and effect of carbonation temperature on the overall yield were investigated. Carbon and hydrogen contents of fish offal were 51.1% and 7.6%, respectively in view of elemental composition. Particularly, nitrogen and sulfur contents were as high as 9.8% and 1.0%, respectively. These values suggests that odor problem of fish offal can be serious. Comparing elemental composition of fish offal with other waste materials, it is thought that carbon and hydrogen contents are considerably high. These implies that thermal disposal will be the best option for final disposal method of fish offal. As a results of carbonization experiments on Mackerel, Hairtail, Croaker and mixed sample of Mackerel, Hairtail and Croaker, carbonization patterns were quite similar irrespective of fish species. Carbonization yield was varied significantly depending on carbonization temperature at the carbonization time of 5 minutes and 10 minutes. When the carbonization time was maintained longer than 30 minutes, yield variation depending on time variation at each temperature was insignificant. Thus, it can be concluded that effect of carbonization time on overall yield was minor when the carbonization time was maintained longer than 30 minutes. Primary vaporization in carbonization conducted at the temperature of $400^{\circ}C$ was minor. Thus, difference of yield between temperature of $500^{\circ}C$ and $400^{\circ}C$ was appeared greatly. It can be concluded that yield difference depending on carbonization temperature can be neglected if the carbonizing temperature exceed $600^{\circ}C$ and carbonizing time exceed 10 minutes at the same time.

• Journal of the Korean Wood Science and Technology
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• v.42 no.1
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• pp.1-12
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• 2014

This study carried out life cycle assessment for evaluating environmental impacts of timber Arch-Truss bridge by using domestic Pinus rigida Miller glued-laminated timber throughout life cycle such as extraction, manufacturing, transportation, construction, use, dismantlement, transportation of waste, disposal and recycling. The life cycle GHG (GreenHouse Gas) emissions of the target bridge are 192.56 ton $CO_2$ eq. in 50 years. Especially, the life cycle GHG emissions of concrete used in the target bridge are 82.84 ton $CO_2$ eq. which accounts for 53.02% of the GWP (Global Warming Potential) in extraction and manufacturing stages. The target bridge is constructed of $116.57m^3$ of domestic Pinus rigida Miller glued-laminated timber and used timber has stored 104.72 ton $CO_2$. If an effect of carbon storage in timber is applied to the total GHG emissions of the target bridge, the GHG emissions can be reduced by 54.38%. In the case of substitution effect, if domestic Pinus rigida Miller glued-laminated timber replaces steel manufactures used in other bridge which has the same structure and life span as the target bridge, the GHG emissions in extraction and manufacturing stages can be reduced by 10.26% to 23.91%.

• Journal of the Korea Organic Resources Recycling Association
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• v.23 no.4
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• pp.86-94
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• 2015

Torrefaction is a thermochemical process proceeded at the temperature around $250^{\circ}C$ in an inert gas condition. By torrefaction, the hemicellulose portions contained in biomass are broken down to change into the volatile gas which is removed from biomass eventually. The main purpose of biomass torrefaction is to improve the energy density of the biomass to minimize the transport energy consumption, though the flammability can be elevated for transportation. In this study two types of solid biomass fuel, waste wood and rice straw, were torrefied at various temperature range from $200^{\circ}C$ to $300^{\circ}C$ to evaluate the torrefied biomass characteristics. In addition torrefied biomass were tested to evaluate the combustion characteristics using TGA (Thermogravimetric Analysis). After the torrefaction of biomass, the C/H (carbon to hydrogen ratio) and C/O (carbon to oxygen ratio) were measured for aquisition of bio-stability as well as combustion pattern. Generally C/H ratio implies the soot formation during combustion, and the C/O ratio for bio-stability. By torrefaction temperature at $300^{\circ}C$, C/H ratio and C/O ratio were increased by two times for C/H and three times for C/O. The torrefied biomass showed similar TGA pattern to coal compared to pure biomass; that is, less mass decrease at lower temperature range for torrefied biomass than the pure biomass.

• Applied Biological Chemistry
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• v.46 no.4
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• pp.291-298
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• 2003

A bacterial strain producing a high level of an extracellular phytase was isolated from livestock waste water, identified as a strain of Pseudomonas fragi and designated as Pseudomonas fragi Y9451. Under the phytase production medium, the activity of phytase reached the highest level after 120 hours of incubation. On the effect of carbon sources on the phytase production, the most favorable carbon source for phytase production was fructose. As for the effect of nitrogen sources, high levels of phytase activity were detected in the medium containing nutrient broth as the nitrogen source. Free $PO_4^{3-}$ inhibited phytase production with increasing concentration of $KE_2PO_4$ and phytate in the media. The addition of $CaCl_2$ and $MgSO_4$ also resulted in the inhibition of phytase production. To investigate the effect of aeration on the phytase production, different volumes of culture broth in Erlenmeyer flasks were incubated in rotary shaker at the speed of 200 rpm. As a result, a high level of phytase activity was detected at small volume of culture broth as compared to larger volume because of its more aerobic condition.

• Journal of Korean Society for Atmospheric Environment
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• v.24 no.4
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• pp.439-454
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• 2008

The purpose of this study was to extensively identify $PM_{10}$ sources and to estimate their contributions to the study area, based on the analysis of the $PM_{10}$ mass concentration and the associated inorganic elements, ions, and total carbon. The contribution of $PM_{10}$ sources was estimated by applying a receptor method because identifying air emission sources were effective way to control the ambient air quality. $PM_{10}$ particles were collected from May to November 2007 in the Yongin-Suwon bordering area. $PM_{10}$ samples were collected on quartz filters by a $PM_{10}$ high-volume air sampler. The inorganic elements (Al, Mn, V, Cr, Fe, Ni, Cu, Zn, Cd, Pb, Si, Ba, Ti and Ag) were analyzed by an ICP-AES after proper pre-treatments of each sample. The ionic components of these $PM_{10}$ samples ($Cl^_$, $NO_3^-$, $SO_4^{2-}$, $Na^+$, $NH_4^+$, $K^+$, $Ca^{2+}$, and $Mg^{2+}$) were analyzed by an IC. The carbon components (OC1, OC2, OC3, OC4, OP, EC1, EC2 and EC3) were also analyzed by DRI/OGC analyzer. Source apportionment of $PM_{10}$ was performed using a positive matrix factorization (PMF) model. After performing PMF modeling, a total of 8 sources were identified and their contribution were estimated. Contributions from each emission source were as follows: 13.8% from oil combustion and industrial related source, 25.4% from soil source, 22.1% from secondary sulfate, 12.3% from secondary nitrate, 17.7% from auto emission including diesel (12.1%) and gasoline (5.6%), 3.1% from waste incineration and 5.6% from Na-rich source. This study provides information on the major sources affecting air quality in the receptor site, and therefore it will help us maintain and manage the ambient air quality in the Yongin-Suwon bordering area by establishing reliable control strategies for the related sources.

• Journal of Energy Engineering
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• v.25 no.4
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• pp.13-29
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• 2016

In this study, we analyzed the causes of major faults in the biogas plant through the case of gas engine failure when cogenerating electricity and heat using biogas as a fuel in the actual sewage treatment plant and suggested countermeasures. Hydrogen sulfide in the biogas entering the biogas engine and water caused by intermittent malfunction of the water removal system caused intercooler corrosion in the biogas engine. In addition, the siloxane in the biogas forms a silicate compound with silicon dioxide, which causes scratches and wear of the piston surface and the inner wall of the cylinder liner. The substances attached to the combustion chamber and the exhaust system were analyzed to be combined with hydrogen sulfide and other impurities. It is believed that hydrogen sulfide was supplied to the desulfurization plant for a long period of time because of the high content of hydrogen sulfide (more than 50ppm) in the biogas and the hydrogen sulfide was introduced into the engine due to the decrease of the removal efficiency due to the breakthrough point of the activated carbon in the desulfurization plant. In addition, the hydrogen sulfide degrades the function of the activated carbon for siloxane removal of the adsorption column, which is considered to be caused by the introduction of unremoved siloxane waste into the engine, resulting in various types of engine failure. Therefore, hydrogen sulfide, siloxane, and water can be regarded as the main causes of the failure of the biogas engine. Among them, hydrogen sulfide reacts with other materials causing failure and can be regarded as a substance having a great influence on the pretreatment process. As a result, optimization of $H_2S$ removal method seems to be an essential measure for stable operation of the biogas engine.

• Journal of the Korean Wood Science and Technology
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• v.27 no.2
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• pp.70-77
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• 1999

Objective of this research is to obtain fundamental data of carbonized wood wastes for soil condition, de-ordorization, absorption of water, carrier for microbial activity, and purifying agent for water quality of river. The carbonization technique and the properties of carbonized wood wastes(thinned trees) are analyzed. Proximate analysis shows the thinned wood contains 0.22-0.73% ash, 77-80% volatile matter, and 10-14% fixed carbon. The charcoal yield decreases and the shrinkage rate increases as the carbonization temperature and time increase. The charcoal yields of Larix leptolepis, Pinus rigida and Pinus densiflora are high, whereas those of Pinus koraiensis and Quercus variabilis are low. The shrinkage rate by carbonization has same trend as water removal of wood. The specific gravity after the carbonization decreases about 50% comparing to green wood. The charcoal has 0.89-4.08% ash, 6.31-13.79% volatile matter, and 73.9-83.5% fixed carbon. As the carbonization temperature and time increase, pH of charcoal increases. When the carbonization temperature is $400^{\circ}C$, pH is about 7.5. When the temperature is between 600 to $800^{\circ}C$, pH is about 10 with small difference. The water-retention capacity is not affected by the carbonization temperature and time. The water-retention capacity within 24hr is about 2.5 - 3times of sample weight, and the equivalent moisture content becomes 2-10% after 24 hr.

• Korean Journal of Agricultural Science
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• v.45 no.2
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• pp.197-203
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• 2018

Biochar is the carbon solid produced through the pyrolysis of a biomass from organic sources such as agricultural waste, animal manure, and sludge under limited or anaerobic conditions. Biochar has the effect of reducing greenhouse gases through the carbon sequestration method; additionally, biochar is known to function as a soil amendment. This experiment was conducted to evaluate the application of biochar on the growth characteristics of Chinese cabbage at Chungnam National University in Daejeon, Korea. The Chinese cabbage was grown for 50 days in a glasshouse in pots. A pruning branch was used to produce the bead and pellet forms of biochar through pyrolysis. The biochar was added to the soil at 0, 2, and 5% by weight. The Chinese cabbage with the 2% treatment of the bead form of biochar had the highest fresh weight ($149.43{\pm}15.92g\;plant^{-1}$) which was increased by 10% compared to the control ($136.91{\pm}31.46g\;plant^{-1}$). Moreover, for the 5% treatment of the bead form of biochar ($60.91{\pm}9.82g\;plant^{-1}$), the growth decreased by 57% compared to the control. As the content of the bead form of biochar increased, the shoot dry weight, leaf number, leaf length and lead width that appeared decreased. An increase in the total organic matter, Avail. $P_2O_5$, Ex. cation and EC was observed when the biochar content was increased. Our results support the application of 2% biochar in the bead form for increased growth of Chinese cabbage.