• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2003.04a
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• pp.73-76
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• 2003

SF$_{6}$ (Sulfur Hexafluoride) is a gaseous compound whose use is being greatly increased recently. The compound has a negligible background concentration from natural sources and is stable in most of groundwater environments. Therefore, SF$_{6}$ has potential for a dating tool for young groundwater. It has many advantages over chlorofluorocarbons (CFCs) for groundwater investigation that sampling procedure is much simpler than CFCs and its growth is continued up to at least near future in the atmosphere. However, solubility of SF$^{6}$ is so low that excess air causes large uncertainties in recharge date of groundwater. To compensate the limitation, $N_2$/Ar method can be employed to estimate excess air content. A groundwater study is currently carrying out in Jeju Island using SF$_{6}$ as an environmental tracer, Well waters and spring waters were sampled for SF$_{6}$ and $N_2$/Ar. To establish SF$_{6}$ input history in the study area, air sampling is being conducted in the area near the center of the island on a monthly and weekly basis. Based on the present data, the level of SF$_{6}$ concentration in the atmosphere of the Island is corresponding to the trend of the Northern Hemisphere.

• Food Science and Biotechnology
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• v.18 no.2
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• pp.343-349
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• 2009

Inhibitory effect of Escherichia coli O157 adhered to Caco-2 cells by the cells of Lactobacillus plantarum K11 and the cell-free culture supernatant (CFCS) and bacteriocin prepared from this strain was investigated. As the cell counts of viable L. plantarum K11 previously adhered to Caco-2 were increased, the rate of adhesion and adherent cell counts of E. coli O157 was lower. However, because the heated L. plantarum K11 rarely have the adhesion ability to Caco-2, the adhesion rate and adherent cell counts of E. coli O157 were high. In addition, the inhibitory effects of E. coli O157 adhesion by the CFCS and bacteriocin of L. plantarum K11 were dose-dependent manner. Therefore, the inhibition of adhesion of E. coli O157 to Caco-2 may result from the antimicrobial substances such as lactic acid and bacteriocin. Moreover the inhibitory activity of adhesion by the heated bacteriocin for 30 min at 100oC was similar to activity of non-treated bacteriocin, but the activity was disappeared by treatment with protease.

• Journal of the Korean Society of Physical Medicine
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• v.14 no.2
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• pp.97-105
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• 2019

PURPOSE: This study examined the factors related to school-based activity performance in school-aged children with spastic cerebral palsy (CP). METHODS: The Gross Motor Function Systems (GMFCS), Manual Ability Classification System (MACS), Communication Function Classification System (CFCS) as functional classifications, and the physical activity performance of the School Function Assessment (SFA) were measured in 79 children with spastic CP to assess the student's performance of specific school-related functional activities. RESULTS: All the function classification systems were correlated significantly with the physical activity performance of the SFA ($r_s=-.47$ to -.80) (p<.05). The MACS (${\beta}=-.59$), GMFCS (${\beta}=-.23$), CFCS (${\beta}=-.21$), and age (${\beta}=-.15$) in order were predictors of the physical activity performance of the SFA (84.8%)(p<.05). CONCLUSION: These functional classification systems can be used to predict the school-based activity performance in school-aged children with CP. In addition, they can contribute to the selection of areas for intensive interventions to improve the school-based activity performance.

• The Journal of Engineering Geology
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• v.26 no.4
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• pp.515-529
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• 2016

In this study, geochemical composition, CFCs (Chlorofluorocarbons), ${\delta}^{18}O$, ${\delta}D$, ${\delta}^{13}C$ isotopes and noble gases isotopes (He, Ne) were analyzed to determine their recharge age, source of $CO_2$ gas and noble gases of carbonated hot spring water and carbonated-water samples collected in the Seoqwipo of the Jeju. The pH of the carbonated waters ranges from 6.21 to 6.84, and the high electrical conductivity range ($1,928{\sim}4,720{\mu}S/cm$). Their chemical composition is classified as $Mg(Ca,\;Na)-HCO_3$ and $Na(Ca,\;Mg)-HCO_3$ types. As a result of the calculation of groundwater age using CFCs concentrations as an environmental tracer, the carbonated water and groundwater were estimated to be about 47.5~57.2 years and about 30.3~49.5 years, respectively. The ${\delta}^{13}C$ values of carbonated water range from -1.77 to -7.27‰, and are plotted on thr deep-seated field or the mixing field of the deep-seated and inorganic origin. Noble gases isotopic ($^3He/^4He$, $^4He/^{20}Ne$) ratio shows that helium gas of carbonated hot waters comes from deep-seated magma origin.

• Applied Chemistry for Engineering
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• v.10 no.7
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• pp.963-968
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• 1999

The global environmental problems have been caused by the release of CFCs. Therefore, methods for safe destruction of recoverd CFCs will be eventually needed. The objective of this study was to develop and test a catalyst operating at a mild condition for the decomposition of CFC-113. In this work, catalytic oxidative decomposition of CFC-113 was carried out over aerosol $TiO_2/SiO_2(ATS)$ catalysts prepared by the sol-gel method. All ATS catalysts(Ti/Si mol ratio=1, 2, 2.33, 4) showed high initial activity. However, the deactivation of ATS catalysts was found that more remarkable due to an attack of fluorine and the destruction of ATS structure(Si-F reaction) from analyses of SEM-EDX, XRD than $TiO_2/SiO_2(ATS)$ catalyst prepared by the precipitation method. ATS catalysts prepared by more acidic prehydrolysis condition were found to have still more activity and longer life-time by increasing of acidity. The activity of ATS catalyst also depend on the content of $TiO_2$. There was reason that the acidity of the ATS catalyst was increased with the increased content of $TiO_2$ from 50 to 80 mol %. Solid superacid catalyst ($ATX/SO_4{^{2-}}$) modified with $H_2SO_4$ solution was prepared for high activity and lower deactivation. The reaction of $ATS/SO_4{^{2-}}$ catalyst also exhibited even higher activity and lower deactivation than the original ATS catalyst. It is suggested that the addition of the sulphate species clearly inhibit the deactivation.

• Composites Research
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• v.28 no.4
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• pp.168-175
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• 2015

Recently, the applications of carbon fiber reinforced plastics (CFRPs) have become broader than ever when it comes to such industries as automotive, ships, aerospace and military because of their lightweight-ness and high mechanical properties. Thermosetting plastics like epoxy are frequently used as the binding matrix in CFRPs due to their high hardness, wetting characteristics and low viscosity. However, they cannot melted and remolded. For this reason, thermosetting plastic wastes have caused serious environmental problems with the production of fiber reinforced plastics. Thus, many studies have focused on the carbon fiber reinforced thermoplastics (CFRTPs) and recycling carbon fiber. In this study, recycled carbon fiber (RCF) was prepared from CFRPs using a pyrolysis method, which was employed to separate resin and carbon fiber. The degree of decomposition for epoxy resin was confirmed from thermal gravimetric analysis (TGA) and scanning electron microscope (SEM). The RCF was cut and ground to prepare a carbon fiber composite sheet (CFCS). CFCS was manufactured by applying recycled carbon fibers and various thermoplastic fibers. Various characterizations were performed, including morphological analyses of surface and cross-section, mechanical properties, and crystallization enthalpy of CFCS at different cooling conditions.

• Korean Journal of Microbiology
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• v.53 no.4
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• pp.273-285
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• 2017

The purpose of this study was to investigate the inhibitory effect of antibacterial substances produced by probiotic lactic acid bacteria (LAB) against biogenic amines-producing bacteria and the influence of culture conditions on the antibacterial activity of bacteriocin and organic acid. The bacteriocin solutions of Lactobacillus plantarum FIL20 (64 AU/ml) and Lactobacillus paracasei FIL31 (128 AU/ml) showed strong antibacterial activity against Serratia marcescens CIH09 and Aeromonas hydrophilia RIH28, respectively. And the lactic acid contents in the cell-free culture supernatants (CFCS) obtained from FIL20 and FIL31 strains were $107.3{\pm}2.7mM$ and $129.5{\pm}4.6mM$, respectively. Therefore, the bacteriocin solution (200 AU/ml) and the CFCS ($200{\mu}l/ml$) produced by L. plantarum FIL20 and L. paracasei FIL31 significantly (P < 0.05) decreased the bacterial numbers and histamine and tyramine production ability of S. marcescens CIH09 and A. hydrophilia RIH28. The amounts of histamine and tyramine produced by the CIH09 strain under conditions of low initial pH (5.0) and incubation temperature ($15^{\circ}C$) was significantly reduced by treatment with bacteriocin solution and CFCS obtained from L. plantarum FIL20. In addition, the bacterial counts and biogenic amines contents of CIH09 strain were significantly decreased (P < 0.05) when sodium chloride (5%) or potassium nitrite (200 mg/g) were mixed with the antibacterial substances of L. plantarum FIL20. Consequently, the bacteriocin and organic acid solution of L. plantarum FIL20 and L. paracasei FIL31 can be used as a biological preservation to effectively control the production of biogenic amines by the application of hurdle technology.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2000.11a
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• pp.231-232
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• 2000

세계기상기구(World Meteorological Organigation : WMO)에서는 추진하고 있는 지구대기감시(Global Atmosphere Watch : GAW)계획을 효율적으로 수행하기 위하여 기상청에서는 안면도 위치한 기존의 배경대기관측소를 2000년 8월부터 지구대기감시관측소로 개칭하고 업무의 추진을 강화하고 있으며 온실기체는 CFCs, CH$_4$, $N_2$O의 경우 1998년 4월부터, $CO_2$는 8월부터 연속 관측을 실시하고있다. (중략)

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2002.04a
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• pp.327-328
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• 2002

대기권 오존의 90%정도가 성층권의 15-30km 부근에 존재한다. 성층권에 존재하는 오존은 대류권에서 생성된 오존과 화학식은 동일하지만 대기 중의 생성과정과 유발시킬 수 있는 피해 정도가 다르다. 성층권 오존은 직접적으로 생체 DNA 변성, 피부암 등을 야기 시키는 자외선을 흡수ㆍ차단시켜 주므로 인간 및 동ㆍ식물에게는 중요한 기체이다. 이러한 성층권 오존이 인간에 의해 배출되는 오염물질 염화불화탄소(CFCs), 할로겐 가스등에 의해 파괴되고 있다. (중략)

• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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• v.28 no.5
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• pp.375-388
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• 1999

1974년 6월 Rowland와 Molina가 CFCs등의 화학물질이 성층권의 오존층을 파괴시킨다는 가설의 발표는 많은 환경론자들의 관심과 함께 논쟁의 대상이 되었다. 이 가설은 1985년 10월 Farman 등의 영국 남극조사팀에 의해 남극상공의 성층권 오존이 1970년대에 비해 약 40% 정도 감소된 것이 확인되면서 지구전체의 심각한 환경문제로 대두되었다.