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- 저자 : 나석은 ( Seok-en Na ) (검색결과 4 건)
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나석은 ( Seok En Na ),최환오 ( Hwan Oh Choi ),이전규 ( Jeon Kyu Lee ),김사영 ( Si Young Kim ),주창식 ( Chang Sik Ju ) 한국화학공학회 2012 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.50 No.5
Stern tube bearing is a shaft device playing important roles to reduce the friction of axial rotation and to support the weight of shaft. However, because there is no domestic producer of stern tube bering, imported stern tube bearings have many practical problems including prices, delivery and after services. This is why stern tube bearing should be localization. For the purpose of development of polyurethane resin for stern tube bearings, the effect of additives on the hardness, tensile strength and elongation of the polyurethane resin were systematically investigated. For the preliminary researches, depending on the type of curing agent, MOCA type and non-MOCA type polyurethanes were synthesized. Preliminary researches concluded that MOCA type polyurethane resin has more excellent mechanical properties than non-MPCA type for stern tube bearings that Tensile strength and Hardness of non-MOCA type investigated 23 D, 4.3 Mpa. Therefore, MOCA type polyurethane was adapted as base resin of this research. Silica, calcium carbonate and graphite were selected as additives for the enhancement of mechanical properties of polyurethane resin. Effect of the type and the dosage of these additives on the hardness, tensile strength, elongation of the polyurethane resin were experimentally examined. However, addition of calcium carbonate and graphite showed only minor effect on the hardness of the resin. Polyurethane resin with silica showed relatively excellent hardness, tensile strength and improved elongation.
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수열합성법에 의한 광촉매 제조 및 Brilliant Blue FCF 분해 성능
김석현 ( Seok-hyeon Kim ),정상구 ( Sang-gu Jeong ),나석은 ( Seok-en Na ),구수진 ( Su-jin Koo ),주창식 ( Chang-sik Ju ) 한국화학공학회 2016 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.54 No.2
Brilliant blue FCF에 대한 분해 특성이 우수한 광촉매를 제조하는 연구를 수행하였다. 먼저 전구체인 titanium (IV) sulfate와 zinc acetate에 침전제로 각각 NaOH, NH₄OH를 첨가하여 비교적 낮은 온도와 상압에서 중간상 형성 없이 1단계의 수열합성법으로 TiO₂와 ZnO를 제조하였다. TiO₂의 경우 제조과정에 양이온성 계면활성제인 CTAB을 첨가하여 제조하기도 하였다. 제조된 TiO₂와 ZnO의 결정성, 입자크기, 흡광도 등과 같은 물리적 특성을 확인하기 위해 XRD, Zeta-potential meter, DRS 등을 사용하여 분석하였다. 광촉매적 특성을 확인하기 위해 회분식 반응장치를 이용하여 UV 조사 하에서 brilliant blue FCF의 광분해 특성을 조사하였다. CTAB을 첨가하지 않은 경우, TiO₂가 ZnO보다 입자가 작고 흡광도와 광촉매 반응의 초기속도가 큰 것을 확인할 수 있었다. 그리고 동일한 제조조건에서 CTAB을 전구체인 Ti(SO₄)₂ 농도의 1/10 첨가하여 제조한 TiO₂는 CTAB을 첨가하지 않은 것보다 brilliant blue FCF의 최종 제거율이 약 15% 정도 우수하였다. Experimental research on the preparation of photocatalyst for the decomposition of brilliant blue FCF(C_{37} H_{31} O_{9}N₂S₃Na₂) was performed. TiO₂ and ZnO powders were prepared from titanium (IV) sulfate and zinc acetate at low reaction temperature and atmospheric pressure by hydrothermal precipitation method without calcination. In addition, TiO₂ was prepared with cationic surfactant CTAB (Hexadecyltrimethyl ammonium bromide) at the same conditions. The physical properties of prepared TiO₂ and ZnO, such as crystallinity, average particle size and absorbance, were investigated by XRD, Zeta-potential meter and DRS. And, the photocatalytic degradation of brilliant blue FCF has been studied in the batch reactor under UV radiation. For the photocatalysts prepared without CTAB, TiO₂ has smaller particle size and larger absorbance and photocatalytic reaction rate than ZnO. And TiO₂, prepared with CTAB whose concentration is 1/10 of that of precursor, shows 15% higher than that prepared without CTAB in final photocatalytic degradation ratio of brilliant blue FCF.
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김석현 ( Seok Hyeon Kim ),나석은 ( Seok En Na ),김시영 ( Si Young Kim ),김성수 ( Seong Soo Kim ),주창식 ( Chang Sik Ju ) 한국화학공학회 2013 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.51 No.4
비교적 낮은 온도와 상압에서 전구체 Titanium(IV) sulfate와 염기성 용액을 반응시키는 수열합성법을 이용하여 소성과정을 거치지 않고 TiO2 나노입자를 제조하였다. 염기성 용액의 종류(NaOH, NH4OH, Monoethanolamine, Diethanolamine, Triethanolamine), 첨가되는 계면활성제의 종류(CTAB, Span 20, SDBS)와 농도, 제조 온도, pH 등을 변화시켜 TiO2를 제조하였고, 생성되는 입자의 결정성, 입자크기 등과 같은 물리적 특성은 XRD, SEM, Zeta-potential 등을 사용하여 분석하였다. 또한, 광촉매적 특성을 확인하기 위하여 DRS를 통해 흡광면적을 측정, 비교하였다. 침전제로 사용된 염기성 물질 중 NaOH가 결정성이 우수하고 입자크기가 작은 TiO2를 제조하는데 가장 효과적임을 확인할 수 있었다. 계면활성제는 양이온성 계면활성제인 CTAB를 첨가한 경우 다른 계면활성제보다 작은 크기의 TiO2를 제조할 수 있었다. 그리고 동일한 조건에서 전구체인 Ti(SO4)2와 CTAB의 농도비를 10 : 1로 조절한 경우 CTAB를 첨가하지 않은 경우보다 제조되는 TiO2 입자의 크기는 약 1/10인 5.8 nm로 감소하였다. Nanosized TiO2 particles were prepared from titanium (IV) sulfate solution using base solutions at low reaction temperature (95 oC) and atmospheric pressure by hydrothermal precipitation method without calcination. The effects of preparation conditions, such as kind of base solutions (NaOH, NH4OH, Monoethanolamine, Diethanolamine, Triethanolamine) and surfactants (CTAB, Span 20, SDBS), concentration of surfactants, temperature and pH, on the physical properties of TiO2 particles have been investigated by XRD, SEM and Zeta-potential meter. Absorption area was also investigated by DRS in order to confirm the photocatalytic activity of the nanosized TiO2 particles. It was turned out that, among base solutions, NaOH provides the smallest TiO2 particles with excellent crystallinity. And cationic surfactant (CTAB) prepared smaller TiO2 particles than any other surfactants. When CTAB is added in the concentration ratio of Ti(SO4)2:CTAB=10:1, TiO2 particles with particle diameter of 5.8 nm were prepared. This is approximately 1/10 of that prepared without CTAB.
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주창식 ( Chang Sik Ju ),정상구 ( Sang Gu Jeong ),나석은 ( Seok En Na ),김시영 ( Si Young Kim ),김석현 ( Scok Hyeon Kim ) 한국화학공학회 2013 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.51 No.2
TiO2 powders were prepared from titanium (IV) sulfate (Ti(SO4)2) solution using ammonia solution at low reaction temperature (80~100 oC) and atmospheric pressure by hydrothermal precipitation method without calcination. The effect of reaction conditions, such as reaction temperature, initial concentration of titanium (IV) sulfate (Ti(SO4)2) solution, pH of mixture solution and the physical properties of the prepared TiO2, such as crystallite structure, crystallite size were investigated. The photocatalytic activity of prepared TiO2 was tested by the photolysis of brilliant blue FCF (BB-FCF) under the UV and the analysis of UV-VIS diffuse reflectance spectroscopy (DRS). The physical properties of prepared TiO2 were examined by X-ray diffraction (XRD), scanning electron microscopy (SEM), photoluminescence spectrometer (PL), particle size distribution measurements. The crystallite size and crystallinity of prepared TiO2 increased with increasing titanium (IV) sulfate (Ti(SO4)2) concentration, but photocatalytic activity decreased. The crystallite size decreased with increasing pH of mixture solution, but photocatalytic activity increased. The crystallinity and photocatalytic activity increased with increasing reaction temperature. The results showed that anatase type TiO2 could be prepared by hydrothermal precipitation method using titanium (IV) sulfate (Ti(SO4)2) solution and ammonia solution at low reaction temperature and atmospheric pressure without calcinations
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