• 한국물환경학회지
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• 제24권1호
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• pp.123-128
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• 2008

The Dissolved Organic Carbon (DOC) existing in a water includes both hydrophobic and hydrophilic substances however, most of the discussion focuses on hydrophobic substances. The hydrophobic fraction was easily removed by absorption or coagulation more than hydrophilic fraction. Therefore, control of the hydrophilic fraction is very important in water treatment process. This study is to determine the variation of DOC, the removal efficiency of DOC, and Trihalomethane formation potential (THMFP) after each stage of water treatment process by fractionating Natural Organic Matters (NOM) into hydrophobic and hydrophilic substance. DOC from raw water was fractionated at acidic pH (pH<2) using XAD 8 resin column, into two fraction : hydrophobic substance (i.e. humic substance) adsorbed on XAD 8 and hydrophilic substance which represent the organics contained in the final effluent. THMFP was carried out according to the following set condition: Cl2/DOC=4 mg/mg, incubation at $25^{\circ}C$ in darkness, pH 7 adjust with HCl or NaOH as necessary, and 72hour-contact time. THMs analyzed in this study were chloroform, bromodichloromethane, dibromochloromethan, and bromoform. Sewage was almost evenly split between the hydrophobic (56%) and hydrophilic fraction (44%). But, Aldrich humic substance (AHS) was found to contain less hydrophilics (14%) than hydrophobics (86%). The formation of THMs may depend on the source which is characterized by the composition of organic matters such as AHS and sewage. The THMFP yield of sewage and AHS were assessed as follows. The value of the THMFP reaction yield, AHS $172.65{\mu}g/mg$, is much higher than that of sewage $41.68{\mu}g/mg$. This illustrates possible significant difference in THMFP according to the component type and the proportion of organic matter existing in water source. Apparently AHS react with chlorine to produce more THMFP than do the smaller molecules found in sewage. Water treatment process may reduce THMFP, nevertheless residual DOC (the more hydrophilic substance) has significant THMFP. Further reduction in organic halide precursors requires application of alternative treatment techniques.

• Macromolecular Research
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• 제8권1호
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• pp.44-52
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• 2000

Styrenic macromonomers with/without a silyloxy-functional group were synthesizedvia chain-end functionalization using 4-vinylbenzyl chloride as a terminating agent insec-butyllithium-initiated polymerization of styrene. The yields were 92 mol% for the silyloxy group and 88 mol% for the styrenic unit. Crystalline polystyrene-g-amorphous polystyrenes were synthesized by (η$^{5}$ -indenyl)-trichlorotitanium ((Ind)TiCl$_3$)-catalyzed copolymerizations of the macromonomers with styrene in the presence of methyl-aluminoxane (MAO) in toluene at 4$0^{\circ}C$. The macromonomer having $\alpha$, $\alpha$'-bis (4-[tert-butyldimethylsilyl-oxy]phenyl) group was also utilized for the preparation of a precursor of hydroxyl-functionalized syndio-tactic polystyrene. The obtained polymers were characterized by a combination of$^1$H, $^{13}$ C NMR spectroscopic, size exclusion chromatographic, and differential scanning calorimetric analysis. The (Ind)TiCl$_3$-catalyzed copolymerization of styrene with the macromonomer carrying the silyloxy functional group was found to be an efficient method to modify syndiotactic polystyrene without a great loss of physica] property by controlling the feud ratio of the macromonomer.

• 유기물자원화
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• 제5권1호
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• pp.25-32
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• 1997

토양에서 분리한 광합성 세균인 Rhodospirillum rubrum N-1 균주에 의한 ${\delta}$-aminolevulinic acid (ALA) 생산에 있어서 levulinic acid (LA) 및 ALA 생합성 경로의 첨가효과를 검토하였다. Glutamate를 제외한 Lascelles의 기본배지에 LA를 배양초기에 10mM, 이후 대수기 중기에 30 mM을 첨가한 결과 균체외의 ALA 생산성은 최고 45 mg/l 도달, LA 미첨가 대비 23배 증가하였다. ALA 생합성의 전구물질인 glycine-succinate ($C_4$) 및 glutamate ($C_5$)의 feeding 효과는 배양초기/대수기 중기에 LA 10/30 mM을, glutamate 30 mM/30 mM을 각각 첨가하는 한편, 대수기 중기에 10 mM 농도의 $C_4$ 전구물질을 별도로 첨가배양함으로써 미첨가 대비의 ALA 생산성이 약 40배 (75 mg/l) 증가하였다.

• 유기물자원화
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• 제5권1호
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• pp.63-69
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• 1997

5-Aminolevulinic acid (ALA) 생합성의 $C_5$ 경로의 전구물질인 L-glutamic acid가 Rhodospirillum rubrum N-1 새포내에서 ALA 생산의 역할을 검토하였다. Lascelles의 기본배지에 L-glutamic acid와 levulinic acid (LA)를 각각 30, 20 mM 첨가배양으로써 균체외 ALA 생산성이 40배 증가(76 mg/l)하였다. 한편 $C_4$ 경로의 기질인 glycine과 succinic acid를 대수기 중기에 각각 60 mM 첨가함으로써, 균의 증식은 억제되었으나 균체외의 ALA는 52 mg/l에 달하였다.

• 한국대기환경학회지
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• 제19권6호
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• pp.663-677
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• 2003

The concentrations of volatile organic compounds (VOCs) in the ambient air were measured at three sites (Samil-dong, SRO and EFMC) in Yeosu industrial complex during September 2000 to August 2001. Air samples were collected for 24 hours in Silicocan canister (6l) with constant flow samplers every 6 days and analyzed using a cryogenic preconcentration system and a GC/MS. At each site, we identified 35 species known as on both the carcinogenic and mutagenicity by the EPA US (TO-14 manual). No relationship was found between YOCs concentration at three sampling points. Furthermore, the result shows that there appears to be a variety distribution of the concentration. BTX, vinyl chloride and high concentrations of 1,2-dichloroethane were observed at the sampling sites. Especially, high concentration of toxic VOCs, such as vinyl chloride, chloroform, 1,2-dichloroethane and benzene were shown at environmental facilities management cooperation (EMFC) site. They seem to be emitted from the facility of wastewater treatment in Yeosu industrial complex. It was difficult to tell the seasonal variation of total VOCs concentration. Nevertheless, the concentration in winter was typically higher than in summer The concentrations of toxic VOCs contents in Yeosu industrial complex were generally lower than those in Ulsan complex, although those were similar or less than in Seoul and Daegu. Whereas, toluene and styrene emitted from Yeosu industrial complex were higher than those of Edmonton industrial complex in Canada. Especially, toluene was third times higher than those observed from Texas, USA.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2003년도 추계학술발표강연 및 논문개요집
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• pp.132-132
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• 2003

Second-order nonlinear optical(NLO) materials have been extensively studied for applications in photonic devices, such as frequency doubling and electro-optical(EO) modulation, because of their large optical nonlinearity, excellent processibility, low dielectric constant, and high laser damage thresholds. The poling behaviour of NLO chromophore in organic/inorganic matrixes showed the randomization of poled NLO chromophore in the absence of poling Held. The liquid crystal molecules in a droplet showed a long-range orientational order along a director. Therefore, liquid crystal effects on poling behaviour of NLO chromophore dispersed in organically modified inorganic sol-gel materials were investigated. Using sol-gel process for the development of NLO material has received increasing attention, Organically modifked inorganic NLO sol-Eel materials are obtained via incorporation of the organic NLO active chromophore into an alkoxysilane based inorganic network. One of the most important thing in this works was that tetraethoxysilane(TEOS) and methyltrimathoxysilane(HTMS) were used as precursor followed by hydrolysis and condensation without using any acidic catalyst during the process. The NLO chromophores in the liquid crystal nanodomains were well mixed with I/O hybrid matrix, deposited on transparent ITO-coated glasses. The poling behaviour of liquid crystal effects of NLO chromophore dispersed in I/O hybrid matrix were investigated by UV-vis spectroscopy. Size distribution and morphology of the NLO chromophores doped in the liquid crystal nanodomains dispersed in I/O hybrid matrix were investigated by SEM.

• Asian Journal of Atmospheric Environment
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• 제11권3호
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• pp.165-175
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• 2017

In Japan, the primary carbonaceous particles emitted from motor vehicles and waste incinerators have been reduced due to strict regulations against exhaust gas. However, the relative contribution of carbonaceous particles derived from plants and biomass has been increasing. Accordingly, compositional analysis of carbonaceous particles has become increasingly important to determine the sources and types of particles produced. To reveal the sources of the organic particles contained in particulate matter with diameters of ${\leq}2.5{\mu}m$ ($PM_{2.5}$) and the processes involved in their generation, we analyzed molecular marker compounds (2-methyltetrols, cis-pinonic acid, and levoglucosan) derived from the plants and biomass in the $PM_{2.5}$ collected during daytime- and nighttime-sampling periods in summer (July and August) and autumn (November) in Kazo, which is in the northern area of Saitama prefecture, Japan. We also measured $^{14}C$ carbonaceous concentrations in the same $PM_{2.5}$ samples. The concentrations of 2-methyltetrols were higher in the summer than in the autumn. Because the deciduous period overlaps with this decrease in the levels of 2-methyltetrols, we considered the emission source to broad-leaved trees. In contrast, the emission source of the cis-pinonic acid precursor was considered to be conifers, because its concentration remained almost constant throughout the year. The concentration of levoglucosan was considerably increased in the autumn due to frequent biomass open burning. The ratio of plant-derived carbon to total carbon, obtained by measuring of $^{14}C$, in summer $PM_{2.5}$ sample was higher in the nighttime, and could be influenced by anthropogenic sources during the daytime.

• 한국진공학회지
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• 제15권5호
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• pp.485-492
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• 2006

새로운 1가 구리 전구체인 $[Cu^I(hfac)]_2(DVTMSO)$ and $[Cu^I(hfac)]_2(HD)$ (hfac=hexa- fluoroacetylacetonate, DVTMSO=1,2-divinyltetramethyldisiloxane, HD=1,5-hexadiene)를 합성하였으며, 또한 유기금속 화학증착법을 사용하여 증착특성을 확인하였다. 새로운 전구체는 기존 구리 1가 전구체와는 다르게 두 개의 Cu(hfac)가 하나의 중성리간드에 결합된 형태를 가지고 있다. 또한 새롭게 합성된 두 종류의 전구체는 기존에 알려진 1가 구리 고체 전구체에 비해 높은 안정성 및 높은 증기압을 가지고 있는 것이 확인하였다. 아울러 기존의 전구체와는 달리 새로운 전구체로 화학증착하면 막 (films)을 형성하지 않고 구리점 (dots)을 형성하는 것을 확인하였으며 이는 새로운 구조로부터 기인된 현상이라고 생각된다. 구리점의 모양은 증착온도에 따라 급격하게 변하는 것도 관찰되었다.

• Composites Research
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• 제32권6호
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• pp.342-348
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• 2019

고분자 재료의 사용이 늘어남에 따라 난연성 고분자 재료에 대한 연구가 더욱 활발히 진행되고 있다. 고분자 재료의 난연성 향상을 위한 방법으로 제조된 섬유의 후처리 또는 섬유내 난연제의 도입에 관한 연구가 진행되고 있다. 많은 고분자들 중 탄소섬유 전구체인 폴리아크릴로니트릴(PAN)은 의류용으로도 많이 사용되고 있어서 낮은 난연성을 지닌 PAN으로 이루어진 소재의 난연성 향상이 절실히 요구되고 있다. 본 총설 논문에서는 PAN 섬유의 후처리(안정화 또는 화학반응)을 통한 난연성 PAN 섬유와, 유/무기 소재(실리카, 2차원 소재, 탄소나노튜브)과 함께 혼합하여 섬유로 제조하는 난연성 PAN 복합소재의 제조에 대한 연구를 소개하고자 한다.

• 한국재료학회지
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• 제20권8호
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• pp.429-433
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• 2010

In this study, activated carbon (AC) as a carbon source was modified with different concentrations of cobalt chloride ($CoCl_2$) to prepare a Co-AC composite, and it was used for the preparation of Co-AC/$TiO_2$ composites with titanium oxysulfate (TOS) as the titanium precursor. The physicochemical properties of the prepared Co-AC/$TiO_2$ composites were characterized by $N_2$ adsorption at 77 K, X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive X-ray (EDX) analysis. The photocatalytic treatments of organic dyes were examined under an irradiation of visible light with different irradiation times. $N_2$ adsorption data showed that the composites had decreased surface area compared with the pristine AC, which was $389\;m^2/g$. From the XRD results, the Co-AC/$TiO_2$ composites contained a mixturephase structuresof anatase and rutile, but a cobalt oxide phase was not detected in the XRD pattern. The EDX results of the Co-AC/$TiO_2$ composites confirmed the presence of various elements, namely, C, O, Ti, and Co. Subsequently, the decomposition of methylene orange (MO, $C_{14}H_{14}N_3NaO_3S$) and rhodamine B (Rh.B, $C_{28}H_{31}ClN_2O_3$) in an aqueous solution, respectively, showed the combined effects of an adsorption effect by AC and the photo degradation effect by $TiO_2$. Especially, the Co particles in the Co-AC/$TiO_2$ composites could enhance the photo degradation behaviors of $TiO_2$ under visible light.