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Control of the size and morphology of nano-size silica particles using a sodium silicate solution
위상욱,이상훈,Seung-Jae Lim,최성철 한양대학교 세라믹연구소 2009 Journal of Ceramic Processing Research Vol.10 No.4
In general nano-sized silica powders are synthesized using the Stber method. A system of chemical reactions has been developed which permits the controlled growth of spherical silica particles of a uniform size by the hydrolysis of alkyl silicates and subsequent condensation of silicic acid in alcoholic solutions. In this study nano silica powders were synthesized using a low cost sodium silicate instead of high cost alkoxide or organo-metallic compound. Cetyltrimethylammonium bromide (CTABr) was used as an additive to control the particle shape and produce a large surface area. The particle shape and specific surface area were controlled with various molar ratios of CTABr, ethyl acetate, DI water and water glass. The nano silica powders were characterized using BET(Brunauer, Emmett & Teller, specific surface area, powder pore size and distribution), and a scanning electron microscope.
위상욱,박영종,최재석,최성철 한양대학교 세라믹연구소 2011 Journal of Ceramic Processing Research Vol.12 No.4
We report vapor-solid growth of Sn-doped and undopedAlNnanorods on n-type Si(100) wafers by halide vapor phase epitaxy via a non-catalytic vapor-solid (VS) growth mechanism. Pure Al and Sn metal powders were used as starting materials, and the reaction temperature was 700 oC. By controlling the HCl flow rate, we confirmed that the morphology of Sn-doped and undopedAlN changed into thin flims, nanorods and nanoneedles. The Sn-doped and undopedAlNnanorodswere 500 nm in length, and diameters were in the range of 15-100 nm. The Sn-doped and undopedAlNnanorods grew along the c-axis. The turn-on field and threshold electric field were decreased from 4.2 to 3.87 V/μm and 6.4 to 5.73 V/μm by Sn-doping, while the estimated field enhancement factorswere increased from 523 to 917.
전처리 정도에 따른 활엽수 표백 크라프트 펄프의 마이크로 피브릴화 셀룰로오스 제조
김은혜,이지영,위상욱 한국공업화학회 2015 한국공업화학회 연구논문 초록집 Vol.2015 No.0
현재 마이크로피브릴화 셀룰로오스 제조법으로는 그라인더, 호모게나이저, 마이크로플루다이저를 이용하여 제조할 수 있다. 그라인더의 경우 마이크로피브릴화셀룰로오스를 제조시 패스회수가 많지만 전기에너지가 적게 소비된다는 장점을 가지고 있다. 하지만 호모게나이저와 마이크로플루다이저의 경우 패스회수는 적으나 전지에너지가 많이 소비되며 막히는 현상이 발생 하며 산업화되기 어렵다고 판단되어진다. 본 연구에서는 마이크로피브릴화 셀룰로오스를 효율적으로 제조하기 위해 전력소모가 가장 작은 그라인더를 제조장비로 선정하였으며 고해를 전처리의 일환으로 하여 고해정도를 달리하여 활엽수 표백크라프트 펄프를 마이크로피브릴화 셀룰로오스 수준으로 미분화 하였다.
이지영,김철환,박종혜,김은혜,위상욱,성용주,허영준,김연오,황인영 한국펄프·종이공학회 2015 펄프.종이技術 Vol.39 No.3
Fluorescent whitening agents (FWAs) are widely applied in the papermaking process to improve the CIE whiteness and the ISO brightness of papers. Large amounts of FWAs are used in the paper and paperboard industry, but no standard method exists for quantitative FWA analysis. Therefore, a new method is needed to analyze the presence of FWAs in paper and paperboard to control their additions and applications. In particular, FWA analysis must concentrate on those used for surface treatment of paper because their use in surface applications has increased recently. The purposes of this study were to measure the optical properties of papers surface-treated with oxidized starch containing FWAs and to deduce the regression equations for the quantitative analysis of FWAs used for surface treatments. Surface sizing was carried out to treat the surface of a base paper with T-FWA and H-FWA, and the pickup weight of the surface sized paper was measured to determine the real weight of FWAs transferred onto the paper surface. After surface sizing and preconditioning, the paper was evaluated for CIE whiteness, ISO brightness, fluorescence index, and reflectance at 440 nm using an Elrepho spectrophotometer. The CIE whiteness and the ISO brightness increased linearly as FWA content increased. The fluorescence index and the reflectance showed linear relationships with T-FWA and H-FWA. Linear regression equations were determined for the quantitative analysis of FWAs used for surface treatments.
6,000 m 고도에 해당하는 급성·평압 저산소 조건에서 키네시오 테이핑 적용이 고유수용성 감각기능에 미치는 영향
김성대,권가람,정일규,위상욱 한국사회체육학회 2020 한국사회체육학회지 Vol.0 No.79
Purpose: It is known that there is impairment in the responses of ther opprioceptive sense function at high altitudes. However, the effect of Kinesio taping (KT) on the response of joint position proprioception to acute normobaric hypoxia remains unclear. The purpose of this study is to evaluate the effect of KT on proprioceptive sense function in a normobaric hypoxic condition corresponding to an altitude of 6,000 m. Method: In a single-blind, balanced crossover study, 18 healthy voluneters (22.7 ± 1.8 years) were randomly allocated to receive either Kinesio taping + hypoxia (KH), hypoxia (HP), or control (CT) with a 1-week interval. For the assessment of proprioceptive sense function,a ctive joint position sense (AJPS) and passive joint position sense (PJPS) were measured at a knee angle of 5°5 of flexion from the maximal passive exte-n sion. KT was applied to different regions of the knee extension muscle group. The acute normobaric hypoxic condition was maintained for 40 minutes using a low oxygen gams ixture. All data were analyzed using twoway ANOVA with repeated measures. Results: The absolute angular error of AJPS in KH and HP was significantly greater than that in CT at posttest (8.0 ± 4.3 and 8.8 ± 6.0, respectively, vs. 2.5 ± 1.3, P<0.01). The absolute angular error of PJPS in KH and HP was significantly greater than that in CT at post-test (7.1 ± 5.5 and 6.8 ± 2.2, respectively, vs. 2.2 ± 1.6, P<0.01). However, the absolute angular error was not significantly different between KH and HP. Conclusion: These results suggest that acute hypoxia impairs the proprioceptive sense function of the knee, and hypoxia-induced damage to proprioceptive sense function is not affected by Kinesio taping.