• 한국재료학회지
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• 제18권6호
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• pp.307-312
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• 2008

In this study, a new cleaning process with a low cost of ownership (CoO) was developed with ozonated DI water ($DIO_3$). An ozone concentration of 40 ppm at room temperature was used to remove organic wax film and particles. Wax residues thicker than $200\;{\AA}$ remained after only a commercial dewaxer treatment. A $DIO_3$ treatment in place of a dewaxer showed a low removal rate on a thick wax layer of $8000\;{\AA}$ due to the diffusion-limited reaction of ozone. A dewaxer was combined with a $DIO_3$ rinse to reduce the wax removal time and remove wax residue completely. Replacing DI rinse with the $DIO_3$ rinse resulted in a surface with a contact angle of less than $5^{\circ}$, which indicates no further cleaning steps would be required. The particle removal efficiency (PRE) was further improved by combining a SC-1 cleaning step with the $DIO_3$ rinsing process. A reduction in the process time was obtained by introducing $DIO_3$ cleaning with a dewaxing process.

• 한국환경과학회지
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• 제8권1호
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• pp.19-26
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• 1999

The degree of pesticides accumulation in tap water in Taejon from June 1995 to Apr 1996 was measured by Ellman's coupled enzyme assay. Since organic phosphate and carbamate pesticides specifically inhibit the neurotransmitter modulating enzyme acetylcholinesterase(AChE), the enzyme activity can be used as a diagnosis for the pesticides accumulation in water and various samples. During the period of this study, the enzyme activity was changed almost every week. The lowest enzyme activity was 64 % of that of the control reaction and there are several days showing about 100 % enzyme activity. In general, the enzyme activity is higher in summer than other seasons especially early spring times. The pH value of tap water was very close to neutral(pH 7.0) and it seems that the enzyme activity was not affected by the small pH changes. Either boiling of tap water or addition of NaOH solution decomposed the pesticide components. These results show that AChE assay is a convenient, sensitive, and reliable method for detection of pesticides in water samples.

• 한국세라믹학회지
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• 제31권3호
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• pp.282-290
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• 1994

In this research, the organic salt [RCOOH] Br with long alkyl-chain was synthesized, and the organophilic [RCOOH]-Montmorillonite was formed by cation-exchange-reaction between Na-Montmorillonite and synthesized organic salt [RCOOH] Br. After drying of the organophilic [RCOOH]-Montmorillonite at $65^{\circ}C$ in high vaccum, the experiments for the probability of forming its complexes with various swelling-solutions as dist, water, methanol, ethanol, acetonitrile, propionitrile, butyronitrile, toluene and n-decanol were performed, and the corresponding basal spacings obtained were 17.44$\AA$, 31.86$\AA$, 34.38$\AA$, 30.37$\AA$, 32.39$\AA$, 35.04$\AA$, 14.16$\AA$ and 14.63$\AA$ respectively.

• 한국재료학회지
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• 제27권5호
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• pp.255-262
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• 2017

Reactive oxygen species (ROS) can be produced by interactions between sunlight and light-absorbing substances in natural water environments and can completely destroy various organic pollutants in waste water. In this study, we used graphene oxide modified $Ag_2Se$ nanoparticles to enhance photochemically generated oxygen (PGO) species activity. Surface area and pore volumes of the $Ag_2Se-graphene$ ($Ag_2Se-G$) samples showed catastrophic decrease due to deposition of $Ag_2Se$. The generation of reactive oxygen species was detected through the oxidation reaction of DPCI to DPCO. The photocurrent density and the PGO effect increase in the case of the use of modified graphene. The PGO effect of the graphene modified with $Ag_2Se$ composites increased significantly due to a synergetic effect between graphene and the $Ag_2Se$ nanoparticles. The photocatalytic activity of sample was evaluated by measuring the degradation of organic pollutants such as methylene blue (MB) and industrial dyes such as Texbrite BA-L (TBA) under visible light.

• Membrane and Water Treatment
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• 제13권6호
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• pp.321-335
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• 2022

Copper-based Metal-organic framework (MOF) namely ([Cu (INA)₂]-MOF) is synthesized by ball milling and characterized using scanning electron microscopy (SEM) for the topography, microstructure, and elemental evidence determination, powdered X-ray diffraction (XRD) for the crystallinity measurement, thermogravimetric (TG) analysis was performed to determine the thermal stability of the material, and Fourier transformed infrared (FTIR) spectroscopy for functional groups identification. The use of [Cu (INA)₂]-MOF as hazardous removal material of β-agonists as persistent hazardous micro-pollutants in our environmental water is first reported in this study. The removal efficiency of the Cu-MOF is successfully determined to be 97.7% within 40 minutes, and the MOF has established an exceptional removal capacity of 835 mg L^-1 with 95 % percent removal on Clenbuterol (CLB) even after the 5th consecutive cycle. The Langmuir model of the adsorption isotherms was shown to be more favourable, while the pseudo-second-order model was found to be favoured in the kinetics. The reaction was exothermic and spontaneous from a thermodynamic standpoint, and the higher temperatures were unfavourable for the adsorption study of the CLB. As a result, the studied MOF have shown promising properties as possible adsorbents for the removal of CLB in wastewater.

• 청정기술
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• 제22권3호
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• pp.175-180
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• 2016

본 연구에서는, 저온 및 약산성 조건에서 높은 활성을 보이는 티로시나아제인 tyrosinase-CNK의 반응 안정성을 조사하였다. Tyrosinase-CNK는 지금까지 알려진 중온성(mesophilic) 및 호열성(thermophilic) 환경 유래의 티로시나아제 보다는 열 안정성이 낮았으나 0 ℃에서 효소 안정성이 매우 뛰어났고, 반복적인 동결-해동(freeze-thaw) 과정에서도 효소 활성을 안정적으로 유지하였다. 또한, 물과 ethanol 및 acetonitrile이 혼합된 유기용매 환경에서 초기 상대 활성 값의 변화가 관찰되었으나 유기용매 농도의 증가로 인한 추가적인 활성 저하를 유발하지 않고 활성을 일정하게 유지하였다. 한편, 효소 반응의 염(salt)에 대한 저해는 chaotropic 특성이 많이 나타나는 염일수록 적게 나타났다. 결과적으로, tyrosinase-CNK는 통상의 티로시나아제를 이용하여 반응을 수행하기 어려운 환경에서도 원하지 않는 반응을 억제하고 효소 불활성화를 최소화면서 반응을 촉매할 것으로 기대된다.

• 한국세라믹학회지
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• 제55권3호
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• pp.261-266
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• 2018

Hollow or bumpy ZnO structures with micrometer-size features have been investigated as photocatalysts for water purification due to their high surface area available for reaction with harmful organic molecules and relatively large size for easy separation after finishing the photocatalytic reaction. In this study, selective synthesis of ZnO hollow or crumpled microspheres was performed using a simple and versatile ultrasonic spray pyrolysis process with various zinc precursors. The morphologies, phases, specific surface areas, and optical properties of the microspheres were characterized using X-ray diffraction, scanning electronic microscopy, nitrogen adsorption-desorption isotherms, and UV-vis spectroscopy. In addition, the mechanism underlying the formation of different morphologies and their photocatalytic activities were systematically investigated.

• 대한화학회지
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• 제9권1호
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• pp.61-65
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• 1965

有機클로로酸, 또는 에스타와 各種金屬(亞鉛, 硅素, 마그네슘, 錫)과의 여러 溶媒存在下(아세트나이트라일, 디옥센 및 토루엔)의 反應에서 얻은 反應生成物, 또는 反應系中의 金屬分布狀態를 (n,${\gamma}$)反應으로 製造한 各種放射性 金屬트레이서를 使用하여 決定하였다. 有機클로로 金屬 콤푸렉스의 溶解度는 親水性溶媒에서는 顯著하게 增加하였으며, 無極性溶媒에는 減少하였다. 이 事實은 回收된 金屬, 또는 回收된 金屬混合物의 水洗液中의 金屬分布狀態의 增加로서 確認되었다. 카보닐化合物 存在下에서 反應시켰 때에도 같은 事實을 나타내었다. 親水性溶媒中의 金屬콤푸렉스의 溶解度는 亞鉛, 硅素, 錫 및 마그네슘이 順序로 減少되었으며 無極性溶媒下에서는 硅素, 錫, 마그네슘 및 亞鉛의 順으로 減少되었다. 有機할로겐化合物과 金屬과의 反應生成物로 普通 豫期되는 有機金屬化合物은 全反應을 通하여 거의 없었다. 反應結果를 論議하였으며, 本反應過程에서 觀察한 溶媒의 影響에 關하여 論及하였다.

• 한국염색가공학회지
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• 제30권2호
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• pp.107-116
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• 2018

Simplification of the manufacturing process in shoe making is essential to improve productivity and reduce production costs. To improve the adhesion of EVA foam used as a midsole, EVA/itaconated EPDM(EPDM-g-IA)(80/20wt%) blend was prepared using Torque Rheometer-Plasti-Corder, and 1,6-hexamethylenediamine/crosslinking agent/foaming agent/additive were mixed, followed by amidation reaction and foaming to prepare EVA/EPDM-g-IA foam for shoe midsole. In this study, we investigate the effect of the content of 1,6-hexamethylenediamine(0, 0.5, 1.0, 2.0, 3.0) on the mechanical properties, water-contact angle and adhesion of EVA/itaconated EPDM foam. As the content of 1,6-hexamethylenediamine increased, mechanical properties such as tensile strength, tear strength, tensile elastic modulus, hardness, and water-contact angle were lowered, but elongation at break and compression set(%) were increased. Both normal type and non-UV type adhesive strength increased with increasing diamine content. In particular, it was found that the adhesion strength of the non-UV type adhesion increased sharply with increasing diamine content. As a result, an adherend rupture occurs in a foam sample having a content of 1,6-hexamethylenediamine of 3phr. From this, it can be seen that the EVA/itaconated EPDM foam for shoe midsoles, which can be used for non-UV adhesion without primer and UV treatments, have been developed.

• 한국환경보건학회지
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• 제27권1호
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• pp.27-35
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• 2001

This aim of the work presented in this paper is to investigate the factors that affcet chlorine decay and to develop functional relationships that can be used to enhance the durability of network models. predictive relationships were established that correlated the rate of chlorine decay to the various water conditions such as DOC, N $H_3$-N, initial chlorine, contact time, temperature and pH values. Free chlorine residual decreased with increasing temperature, DOC, N $H_3$-N, reaction time and chlorine dose. At 2$0^{\circ}C$, pH 7, The initial chlorine demand per mg as DOC/L and mg as N $H_3$-N/L was about 0.43, 2.69 mg/$\ell$ respectively at 180 minutes contact time. The Reaction between chlorine and humic acids was lasted intil 48hr, but the reaction between chlorine and N $H_3$-N was almost completed in 180 min. When the temperature is raised by 1$0^{\circ}C$, chlorine is more consumed about 0.25 mg/$\ell$ in the absence of organic substances and it is more consumed about 3.4 mg/$\ell$ in the presence of humic acid (5 mg/$\ell$) in water at pH 7 for 180 min. Regression Analysis created the resulting prediction equation for the chlorine decay in a SPSS package of the computer system. The model is as follows; $C_{t}$=1.239+0.707(Co)-0.000529(Time)-0.0112(Temp)+0.02227(pH)-0.42(DOC)-2.132(N $H_3$-N).).