• Preventive Nutrition and Food Science
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• v.7 no.4
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• pp.378-385
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• 2002

Oxidant radicals are implicated as a causal factor in the pathogenesis of neurobiological disorders and neuro-degenerative diseases. The objective of this study was to investigate the antioxidant activity of edible plants against oxidative stress in bovine brain tissue. Fifty five kinds of edible plants grown in Korea were dried either by freeze-drying or hot-air drying (7$0^{\circ}C$), and evaluated for their antioxidant activity by measuring TBARS (thiobarbituric acid-reactive substances) in brain homogenates subjected to Fe$^{+2}$_mediated lipid peroxidation with or without the addition of botanical extracts. Heat-drying decreased the antioxidant activity of most plant extracts by 10~81%, compared with freeze-drying. However, Aruncus americanus, Ligularia stenocephala, Artemisia princceps var. orientalis, Petasites japonicus and Aster scaber showed very strong antioxidant activities regardless of processing, with or without heat treatment. The $IC_{50}$/ values of the methanol extracts from these edible plants were in the range of 0.093~0.379 mg/$m\ell$, which was lower than that of ascorbic acid (0.79 mg/$m\ell$). Thermal processing of some edible plants enhanced their antioxidant activity.

• International Journal of Automotive Technology
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• v.3 no.3
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• pp.111-115
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• 2002

Suddenly increasing numbers of automobiles result in making worse air pollution problems. In particular, the emissions from automobiles affect badly on atmosphere. Nowadays, research on catalyst converter and filter trap as a modem technology is very active because PM is designated as a major cancer material and stringent regulations on this are necessary and required. The ceramic filter is very efficient in reducing particular materials up to 80-90% and is evaluated as a very efficient after-treatment technology. However, it comes with decreased engine performance due to increased back-pressure occurred by thermal crack. In order to solve these problems, several methods are proposed such as fuel additive, electric heater and burner types. This experimental study has been conducted with equipped and unequipped a ceramic filter on a displacement 11,000cc diesel engine and compared in terms of engine performance and emission. To measure the emission, D-13 mode is applied and measured quantities of the exhaust gases, particularly in CO, HC, PM, and NOx. Therefore, this research is focused on the basic mechanism and characteristics on harmful materials generated by ceramic filter.

• Journal of Sensor Science and Technology
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• v.21 no.3
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• pp.167-171
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• 2012

Ag- and Pd-loaded $SnO_2$ nanowire network sensors were prepared by the growth of $SnO_2$ nanowires via thermal evaporation, the coating of slurry containing $SnO_2$ nanowires, and dropping of a droplet containing Ag or Pd nanoparticles, and subsequent heat treatment. All the pristine, Pd-loaded and Ag-loaded $SnO_2$ nanowire networks showed the selective detection of $C_2H_5OH$ with low cross-responses to CO, $H_2$, $C_3H_8$, and $NH_3$. However, the relative gas responses and gas selectivity depended closely on the catalyst loading. The loading of Pd enhanced the responses($R_a/R_g$: $R_a$: resistance in air, $R_g$: resistance in gas) to CO and $H_2$ significantly, while it slightly deteriorated the response to $C_2H_5OH$. In contrast, a 3.1-fold enhancement was observed in the response to 100 ppm $C_2H_5OH$ by loading of Ag onto $SnO_2$ nanowire networks. The role of Ag catalysts in the highly sensitive and selective detection of $C_2H_5OH$ is discussed.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.515-515
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• 2007

$LiCoO_2$ powder was synthesized by Sol-Gel method using inorganic materials. The starting materials, $CH_3COOLi^*2H_2O\;and\;Co(CH_3COO)_2{^*}4H_2O$, were mixed in the atomic ratio Li/Co of 1 and dissolved in i-propanol with acetic acid. The solution was dried for gelation, and finally obtained the pre-powder. The pre-powder were studied by thermal analysis. Based on the TGA result, heat treatment was performed at various temperature(500 to $800^{\circ}C$) for 2h in air atmosphere. The crystal structure, morphology, electrochemical property were carried out using XRD, SEM, cyclic voltammetry(CV).

• Journal of the Microelectronics and Packaging Society
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• v.27 no.4
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• pp.11-17
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• 2020

Copper has been proved to be the best catalyst for electrochemical CO2 reduction reaction, however, for optimal efficiency and selectivity, its performance requires improvements. Electrochemical CO2 reduction reaction (RR) using CuO nanowire electrode was performed with different concentrations of KHCO3 electrolyte (0.1 M, 0.5 M, and 1 M). Cu(OH)2 was formed on Cu foil, followed by thermal-treatment at 200℃ under the air atmosphere for 2 hrs to transform it to the crystalline phase of CuO. We evaluated the effects of different KHCO3 electrolyte concentrations on electrochemical CO2 reduction reaction (RR) using the CuO nanowire electrode. At a constant current (5mA), low concentrated bicarbonate exhibited a more negative potential -0.77 V vs. Reversible Hydrogen Electrode (RHE) (briefly abbreviated as VRHE), while the negative potential reduced to -0.33 VRHE in the high concentration of bicarbonate solution. Production of H2 and CH4 increased with an increased concentration of electrolyte (KHCO3). CH4 production efficiency was high at low negative potential whereas HCOOH was not influenced by bicarbonate concentration. Our study provides insights into efficient, economically viable, and sustainable methods of mitigating the harmful environmental effects of CO2 emission.

• Journal of the Korean Institute of Gas
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• v.24 no.6
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• pp.1-10
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• 2020

Reactivity controlled compression ignition (RCCI) combustion is one of dual-fuel combustion systems which can be constructed by early diesel injection during the compression stroke to improve premixing between diesel and air. As a result, RCCI combustion promises low nitrogen oxides (NOx) and smoke emissions comparing to those of general dual-fuel combustion. For this combustion system, to meet the intensified emission regulations without emission after-treatment systems, exhaust gas recirculation (EGR) is necessary to reduce combustion temperature with lean premixed mixture condition. However, since EGR is supplied from the front of turbocharger system, intake pressure and the amount of fresh air supplementation are decreased as increasing EGR rate. For this reason, the effect of various EGR rates on the brake power and thermal efficiency of natural gas/diesel RCCI combustion under two different operating conditions in a 6 L compression ignition engine. Varying EGR rate would influence on the combustion characteristic and boosting condition simultaneously. For the 1,200/29 kW and 1,800 rpm/(lower than) 90 kW conditions, NOx and smoke emissions were controlled lower than the emission regulation of 'Tier-4 final' and the maximum in-cylinder pressure was 160 bar for the indurance of engine system. The results showed that under 1,200 rpm/29 kW condition, there were no changes in brake power and thermal efficiency. On the other hand, under 1,800 rpm condition, brake power and thermal efficieny were decreased from 90 to 65 kW and from 37 to 33 % respectively, because of deceasing intake pressure (from 2.3 to 1.8 bar). Therefore, it is better to supply EGR from the rear of compressor, i.e. low pressure EGR (LP-EGR) system, comparing to high pressure EGR (HP-EGR) for the improvement of RCCI power and thermal efficiency.

• Journal of Environmental Science International
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• v.22 no.1
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• pp.91-98
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• 2013

In order to study the seasonal patterns and possible origins of air concentrations of volatile organic compounds(VOC), measurements were taken with GC-MS at 3 sampling sites in Jinju for 12 months from Mar. 2010 to Feb. 2011. Atmospheric VOC are sampled on tubes containing solid adsorbents(Tenax TA) with a time resolution of 2hrs. Composition and concentration of VOC are analysed with a GC system equipped with thermal desorption apparatus(ATD). The most abundant compound appeared to be Toluene, Ethylbenzene and m,p-Xylene. The mean concentrations of Benzene were 0.20 ppb at GN site, 0.18 ppb at DA site, and 0.25 ppb at SP site, respectively. VOC concentration showed a strong seasonal variation, with higher concentrations during the spring and lower concentrations during the summer. The results showed that monthly fluctuations in measured VOC concentrations depended on variations in the strength of sources, as well as on photochemical activity and meteorological conditions. In Jinju, the total VOC emissions for 2009 were estimated to be 4,407 ton/year by Clean Air Policy Support System(CAPSS). It is shown that solvent use 57.5%(2,534 ton/yr), waste treatment and disposal 23.3%(1,025 ton/yr), and mobil source-road traffic 12.2%(537 ton/yr) are the most significant anthropogenic source.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.11
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• pp.3246-3252
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• 2009

The interest on the recovery of thermal energy using the waste has been rising to solve the problems of continuous increase of waste generation and the depletion of the fossil fuel recently. The incineration has been used most popularly as a treatment process of the waste for the energy recovery. However, it is expected that incineration and design cost will increase in the treatment of air contaminant emitted from incinerator. This research has simulated the actual incinerator and the flue gas treatment system using the Aspen plus which is the software to simulate the chemical process. The incineration process is composed of the 1st and 2nd combustor to burn the waste, SNCR process to reduce the $NO_x$ using the urea, and the steam generation process to save the energy during incineration. The $Ca(OH)_2$ slurry was used as an acid gas (HCl, $SO_2$) treatment materials and the removal efficiency for the products from the neutralization of acid gas in SDA and combustion ash was simulated at the bag filter. The simulation result has been corresponded with the treatment efficiency of emitted gas from the actual industrial waste incinerator and it is presumed to be used to forecast the efficiencies of flue gas treatment system in the future.

• Journal of the Korean Wood Science and Technology
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• v.44 no.5
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• pp.776-784
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• 2016

In this study, green Larix kaempferi lumber was heat-treated by using superheated steam (SHS) at a pilot scale and then various physico-mechanical properties of the heat-treated wood were evaluated and compared with the properties of conventional hot air (HA) heat-treated wood. Decay resistance of brown rot fungi and compressive strength parallel to the grain of the SHS heat-treated wood without occurrence of drying check from green lumber were increased. On the other hand, density, equilibrium moisture content, shrinkage, and bending strength of the SHS heat-treated wood were lower than those of the conventional HA heat-treated wood. Because heat transfer and thermal hydrolysis of SHS heat treatment was accelerated by a large amount of water, the effect of SHS heat treatment on the physico-mechanical properties was higher than that of HA heat treatment at the similar conditions of temperature and time. From the results of this study, because green lumber can be heat-treated without occurrence of cracks or checks by using SHS and similar heat treatment effect on the physico-mechanical properties of wood can be produced despite a low temperature or short time of heat treatment, it is expected that heat time and energy consumption could be reduced by using SHS.

• Journal of the Korean Society of Clothing and Textiles
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• v.29 no.7 s.144
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• pp.997-1007
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• 2005

The textile finishing methods utilizing chitosan have been mostly focused on the applications in the improvement of the dyeing of cotton fabrics, or the improvement of hand of the cotton or wool fabrics. On the other hand, it Is difficult to find the application examples in the synthetic fiber fabrics including polyester and nylon fabrics. The aim of this study is to improve the stiffness and the poor wash fastness of the fabrics treated only with chitosan. We tried to improve the softness by employing chitosan and polyurethane mixture solution and to prevent the detachment of the chitosan from the fabric. The treatment was applied to cotton, polyester, and nylon fabrics. The change of the properties of the treated fabrics were investigated. The optimum finishing condition was sought by changing the mixture ratio of the chitosan/PU(polyurethane) solutions. The adjusted ratios of the chitosan/PU solutions were 1 : 0, 1 : 0.25, 1 : 0.5, and 1 : 2 during the mixture solution preparation. Using the KES(Kawabata Evaluation System), the physical and mechanical properties of the finished fabric specimens were analyzed, and hand values of the specimens were calculated through the use of translational formulas. According to the chemical composition of the fibers, chitosan solution or chitosan/PU mixture exhibited wide range of coating effect. Since the chitosan acid solution has high polarity, the bonding force with the cotton fibers is high. By the appropriate addition of PU in the chitosan treatment of cotton, KOSHI and HARI values of the fabric improved. The air permeability of the chitosan/PU treated cotton fabric specimen improved, resulting in the highest value at the mixture of chitosan : PU=1:0.25.