• 한국염색가공학회지
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• 제27권2호
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• pp.113-118
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• 2015

Poly(vinyl butyral), PVB was photooxidized by UV/ozone irradiation and the effect of UV energy on the surface properties of the UV-irradiated PVB film were investigated by the measurement of reflectance, surface roughness, contact angles, elemental composition, and zeta potential. With increasing UV energy, reflectance decreased in the visible and ultraviolet regions particularly at the wavelength of 400nm. The irradiation produced nano-scale surface roughness including the maximum peak-to-valley roughness increased from 274nm for the unirradiated PVB to 370nm at the UV energy of $5.3J/cm^2$. The improved hydrophilicity was due to the higher $O_{1s}/C_{1s}$ resulting from the introduction of polar groups such as C=O bonds. The surface energy of the PVB film increased from $35.3mJ/m^2$ to $39.3mJ/m^2$ at the irradiation of $15.9J/cm^2$. While the zeta potentials decreased proportionally with increasing UV energy, the cationic dyeability of the PVB increased accordingly resulting from the improved affinity of the irradiated PVB surfaces containing the photochemically introduced anionic and dipolar dyeing sites.

• Journal of Plant Biology
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• 제33권2호
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• pp.111-118
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• 1990

In order to characterize the chloroplasts of Korean ginseng as a semi-shade plant and radish as a sun plant, effects of growth light intensity on photosynthetic electron transport (PS) activity in chloroplasts and superoxide (O2.-) production in thylakoid membrane by irradiation were investigated. High-light chloroplasts of both plants showed higher PS activities than those grown under ow growth light intensity. High PS II and low PS I activities in ginseng chloroplasts (ratio of PS II/PS I : 1.1) were observed, but radish chloroplasts showed low PS II and high PS I activities (ratio of PS II/PS I : 0.3). PS II activity of both plants was little affected by temperature in range of 15-35$^{\circ}C$. Activities of whole -chain (PS II+I) in ginseng and PS I in radish were increased at high temperature (4$0^{\circ}C$). Preincubation of chloroplasts at 4$0^{\circ}C$ during 30 min, as a mild heat stress, caused rapid decrease in PS II and PS II+I activities of both plants. However PS I activity was not decreased in ginseng and rather increased in radish. O2.- production (NBT reduction) in Mehler reaction in the thylakoid membrane was inhibited by DCMU in both plants. DMBIB inhibited O2.- production in ginseng, but radish was insensitive to DMBIB. Electron flow system in ginseng thylakoid membrane was more susceptible to damage of photooxidation than that of radish.

• 한국환경과학회지
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• 제15권9호
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• pp.855-864
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• 2006

This study introduces a method to eliminate formaldehyde and benzene, toluene from indoor air by means of a photocatalytic oxidation reaction. In the method introduced, for the good performance of the reaction, the effect and interactions of the $TiO_2$ catalyst and ultraviolet in photocatalytic degradation on the reaction area, dosages of catalysts, humidity and light should be precisely examined and controled. Experiments has been carried out under various intensities of UV light and initial concentrations of formaldehyde, benzene and toluene to investigate the removal efficiency of the pollutants. Reactors in the experiments consist of an annular type Pyrex glass flow reactor and an 11W germicidal lamp. Results of the experiments showed reduction of formaldehyde, benzene and toluene in ultraviolet $/TiO_2/$ activated carbon processes (photooxidation-photocatalytic oxidation-adsorption processes), from 98% to 90%, from 98% to 93% and from 99% to 97% respectively. Form the results we can get a conclusion that a ultraviolet/Tio2/activated carbon system used in the method introduced is a powerful one for th treatment of formaldehyde, benzene and toluene of indoor spaces.

• 한국환경과학회지
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• 제13권1호
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• pp.37-40
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• 2004

In this study, the decomposition of gas-phase TCE, Benzene and Toluene, in air streams by direct UV Photolysis and UV/TiO$_2$ process was studied. For direct UV Photolysis, by regressing with computer calculation to the experimental results the value of reaction rate constant k of TCE, Toluene and Benzene in this work were determined to be 0.00392s$\^$-l/, 0.00230s$\^$-1/ and 0.00126s$\^$-1/, respectively. And the adsorption constant K of TCE, Toluene and Benzene in this work were determined to be 0.0519 mol$\^$-l/ ,0.0313mo1$\^$-1/ and 0.0084mo1$\^$-1/, respectively. For UV/TiO$_2$ system by regressing with computer calculation to the experimental results the value of reaction rate constant k of TCE, Toluene, and Benzene in this work were determined to be 5.74g/$\ell$$.$min, 3.85g/$\ell$$.$min, and 1.18g/$\ell$$.$min, respectively. And the catalyst adsorption constant K of TCE, Toluene, and Benzene in this work were determined to be 0.0005㎥/mg, 0.0043㎥/mg and 0.0048㎥/mg, respectively.

• Journal of Photoscience
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• 제3권3호
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• pp.167-169
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• 1996

Absorption of UV light induces photocleavage of polymer chains to produce free radicals which initiate photodegradation of the polymer molecules. Discoloration, cracking of surface, stiffening, and decreasing of mechanical properties of polymeric products occur as a result of photodegradation of the polymers. Photostabilizers are added to the polymer systems in order to minimize the unwanted effects of UV light. It is well known that Hindered Amine Light Stabilizers (HALS) are one of the most effective photostabilizer for polymers.' HALS have been used in a large number of commercial polymers and predominantly used in styrenic and engineering plastics. They are efficient and cost-effective in many applications despite their high prices. However, low molecular weight HALS vaporize easily, emitting harmful amines, and have poor extraction resistance, decreasing their photostabilization effect. They also decompose during processing and migrate within the polymers resulting in deposition on the polymer surfaces called 'blooming". These drawbacks of low molecular HALS can be overcome by use of the polymeric HALS. We have been studying photochemical reactions of the polymer systems. The present paper reports the preparation of a new polymeric photostabilizer containing HALS groups and their stabilization effects on photooxidation of polystyrene. The synthetic scheme for the preparation of polymeric photostabilizers containing HALS groups were shown at Scheme 1. N-[(Chloroformyl) phenyl]maleimide (CPMI) and N-[4-(chlorocarbonyl) phenyl]maleimide (CPMIC) were prepared by the known procedure. N[4-N'-(2,2,6,6-tetramethyl-4-piperidinyl)aminocarbonyl-phenyl] maleimide (TMPI) was prepared by the reaction of CPMI with 4-amino-2,2,6,6-tetramethylpiperidine (ATMP).

• Journal of Photoscience
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• 제11권2호
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• pp.77-81
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• 2004

Deoxygadusol (DO) and structurally related mycosporine-like amino acids, i.e. mycosporine glycine (MO) and mycosporine taurine (MT), were isolated from phytoplankton Prorocentrum micans and studied for the reactivity toward singlet oxygen. These water-soluble compounds with a cyclohexenone chromophore were all shown to be highly effective in quenching singlet oxygen ($^1$ $O_2$), with the efficiencies being significantly larger compared with histidine, a well-known $^1$ $O_2$ quencher. The $^1$ $O_2$ reaction rate constant ( $k_{Q}$) of DG was determined to be 5.4 ${\times}$ 10$^{7}$ $M^{-1}$ $s^{-1}$ by a steady state method based on competitive inhibition of rubrene oxidation. The feasibility of this method was confirmed by estimating the $k_{Q}$ values for MG and two other quenchers, furfuryl alcohol and 1,4-diazabicyclo [2,2,2]octane, and comparing with those values determined by the time-resolved $^1$ $O_2$ decay method in the previous work.ork.

• 대한화학회지
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• 제19권6호
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• pp.454-462
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• 1975

금속의 착물을 첨가제로 사용하여 햇빛에 의한 고분자 물질의 분해를 빠르게 하고자 하였다. 첨가제는 햇빛의 자외선에 의해 들뜬상태가 되어 공기중의 산소를 들뜬 단일상태로 만들어 준다. 들뜬 산소는 고분자의 골격에 카르보닐기나 히드록실기와 같은 작용기를 만들어 주며 동시에 골격을 끊어준다. 이러한 작용기는 미생물에 의해 공격받기 쉬우므로 고분자물질은 점점 저분자 물질로 되어 분해된다 적외선 스펙트럼으로 이러한 작용기들의 생성을 측정하였으며, 점성도의 측정과 비교하여 이러한 기들의 생성이 분자량의 감소와 비례함을 알았다. 첨가제의 종류를 바꾸어 가며 그 효과를 비교함으로써 350${\sim}$400nm의 자외선에서 센 charge-transfer band를 가지는 금속착물이 효과가 좋으며 특히 철의 디티오카르밤산 착물과 그와 유사한 구조의 착물이 좋은 효과를 보여줌을 알았다.

• 한국잡초학회지
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• 제9권3호
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• pp.230-237
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• 1989

Bleaching herbicides(oxyfluorfen, oxadiazon, paraquat)의 작용발현에 영향을 미치는 온도 및 광의 효과를 조사한 결과 oxyfluorfen 과 oxadiazon의 제초활성은 $10-35^{\circ}C$에서 온도가 증가될수록 높았으며 온도의 효과는 제초작용 발현단계(photooxidation) 보다는 그 이전 단계에서 더욱 큰 영향이었다. 처리약제 모두 광도가 높을수록 활성이 강하였으며 paraquat 는 광질간의 활성차이가 없었으나 oxyfluorfen 및 oxadiazon 은 챙색광에서 높은 활성을 보였고 이들 두 약제에 대한 광의 효과는 광합성 및 호흡의 전자전달계나 carotenoid 생합성 보다는 chlorophyll 생합성 과정과 일정한 관련이 있다.

• 한국염색가공학회지
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• 제26권3호
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• pp.159-164
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• 2014

Biodegradable Poly(butylene succinate), PBS, was photooxidized by UV/ozone irradiation and the effect of UV energy on the surface properties of the UV-irradiated PBS film were investigated by the measurement of reflectance, surface roughness, contact angles, chemical composition, and zeta potential. With increasing UV energy, reflectance decreased in the visible and ultraviolet regions particularly at the wavelength of 380nm. The irradiation produced nano-scale surface roughness including the maximum peak-to-valley roughness increased from 106nm for the unirradiated sample to 221nm at the UV energy of $10.6J/cm^2$. The improved hydrophilicity was due to the higher $O_{1s}/C_{1s}$ resulting from the introduction of polar groups such as C-O and C=O bonds. The surface energy of the PBS increased from $42.1mJ/m^2$ for the unirradiated PBS to $56.8mJ/m^2$ at the irradiation of $21.2J/cm^2$. The zeta potentials of the UV-irradiated PBS also decreased proportionally with increasing UV energy. The cationic dyeability of the PBS increased accordingly resulting from the improved affinity of the irradiated PBS surfaces containing photochemically introduced anionic and dipolar dyeing sites.

• 한국염색가공학회지
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• 제21권4호
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• pp.33-38
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• 2009

Poly(vinyl acetate) films containing benzophenone were photocrosslinked by continuous UV irradiation.UV irradiation of PVAc film containing 5% benzophenone induced bulk crosslinking of the polymer indicated by 84.1% of gel fraction after ethyl acetate extraction. The crosslinking was attributed to the recombination of tertiary polymer radicals generated upon UV irradiation, which was enhanced by the hydrogen abstraction of benzophenone. Also the UV irradiation resulted in scission of ester linkage and photooxidation of PVAc surface, which was verified by ATR and zeta potential analysis, implying that the PVAc surface became more polar and hydrophilic. The zeta potential proportionally increased from +4.5mV to -26.8 mV with increasing UV irradiation. Also the surface energy of the PVAc film increased with higher UV irradiation upto 56.5 $mJ/m^2$ by the enhanced Lewis acid/base component with larger contribution of Lewis acid parameter. Accordingly the crosslinked PVAc showed higher thermal stability with increasing UV energy.