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알코올-물 혼합용액을 이용하는 Solvothermal 법에 의한 나노크기의 TiO<sub>2</sub> 제조
이상근,박성수,홍성수,박종명,이승호,김대성,이근대,Lee, Sang Geun,Park, Seong Soo,Hong, Seong Soo,Park, Jong Myung,Lee, Seung Ho,Kim, Dae Sung,Lee, Gun Dae 한국공업화학회 2011 공업화학 Vol.22 No.6
본 연구에서는 $TiCl_4$ 출발물질 및 알코올과 물의 혼합용액을 이용한 solvothermal 법을 통하여 나노 크기의 $TiO_2$를 제조하였다. 이 때 혼합용액 중의 알코올의 종류 및 그 조성이 생성되는 $TiO_2$ 입자들의 결정상 혹은 응집상태에 미치는 영향에 대해 조사하였다. 생성물들의 물성은 X-선 회절법과 투과 및 주사전자 현미경을 이용하여 분석하였다. 1-부탄올/물의 부피 비가 각각 다른 혼합용매(1-부탄올/물; 100/0, 75/25, 50/50, 25/75, 0/100)를 이용한 solvothermal 법에 있어서 얻어진 루틸상의 $TiO_2$ 입자들의 응집상태는 1-부탄올/물의 비에 따라 변하였으며, 1-부탄올/물의 75/25 부피 비에서 잘 분산된 $TiO_2$ 나노 입자가 얻어졌다. 알코올과 물의 비를 75/25로 고정시킨 혼합 용매를 이용한 solvothermal 법에 있어서 알코올의 종류에 따라 생성되는 $TiO_2$ 입자들의 결정상이 변함을 확인하였다. 즉 메탄올, 에탄올 및 이소프로필 알코올의 혼합용액을 사용한 경우에는 아나타제상의 입자가 얻어지며 1-부탄올 혼합용액을 사용하면 루틸상의 $TiO_2$ 입자가 생성되었다. 이상의 결과들로부터 출발물질로는 $TiCl_4$를 그리고 반응용매로 알코올과 물의 혼합용액을 이용하며 더 이상의 첨가제를 사용하지 않는 solvothermal 법에 있어서는, 단순히 혼합용액의 조성 또는 알코올의 종류를 변화시킴으로써 생성되는 $TiO_2$ 입자들의 분산성 향상 및 결정상 조절이 가능한 것을 확인할 수 있었다. In this study, a solvothermal reaction to prepare nanocrystalline titania was carried out using $TiCl_4$ and mixed solvents of alcohol and water. The effects of the type and the composition of alcohol on the crystal structure and agglomeration of final $TiO_2$ products were investigated. The products were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) as well as scanning electron microscopy (SEM). In the solvothermal reaction using the n-butanol solutions with different volume ratios of n-butanol/water (100/0, 75/25, 50/50, 25/75, 0/100), the extent of agglomeration of obtained rutile $TiO_2$ was found to change with the volume ratio of n-butanol/water, and the n-butanol/water ratio of 75/25 revealed the best result for the preparation of well-dispersed nanocrystalline $TiO_2$ powders. The crystal phase of $TiO_2$ prepared through the solvothermal reaction changed with the type of alcohol in solvent (alcohol/water = 75/25). $TiO_2$ products obtained with the aqueous solutions of methanol, ethanol and isopropanol have an anatase phase, while that with n-butanol has a rutile phase. The results showed that, in the solvothermal reaction using both $TiCl_4$ as a starting material and the alcohol-water mixed solvents without any other additive, the enhancement of dispersion and control of crystal structure of $TiO_2$ products can be feasible by simply varying the composition and type of alcohol in the mixed solvents.
이상근,Young-Guk Ko,Donghoon Choi,Do-yun Lee 대한심장학회 2013 Korean Circulation Journal Vol.43 No.6
Endovascular aneurysm repair (EVAR) using stent grafts has shown to be an effective alternative to surgical repair in treating an abdomi-nal aortic aneurysm (AAA). EVAR is associated with shorter hospital stays, less blood loss, shorter operating times, and lower early mor-bidity and mortality compared to open surgical repair, although EVAR required a higher reintervention rate during a longer follow-up peri-od. However, short or severely an angulated infrarenal proximal aortic neck is considered unsuitable for EVAR. The chimney graft technique is a modified procedure based on the deployment of a covered or bare-metal stent parallel to the main aortic endograft within the aneurysm,thereby creating a conduit that runs outside the aortic main endograft to preserve flow to the aortic branches. In this case report, we present a 78-year-old patient with an AAA with a short and severely angulated proximal neck who was successfully treated by EVAR using the chimney graft technique.
이상근,이춘구,Lee, Sang-Keun,Lee, Chun-Goo 영남수학회 2010 East Asian mathematical journal Vol.26 No.2
In this study, we study on the length of bisector of angle by the method using the area, the method using the vector and the method using the similarity, also the length of trisector of angle by the method using the sine law, the method using the area and the method using the second law of cosine in triangle, respectively. And we study on the length of trisector of angle with the length of bisector in angle. This study is expected to use the learning materials for the interesting construction and the problem solving using trigonometric functions.
Morley 정리의 한 증명방법과 그 활용에 대한 연구
이상근,이춘구,Lee, Sang-Keun,Lee, Chun-Goo 영남수학회 2008 East Asian mathematical journal Vol.24 No.5
In this study, we'll check the proof of Morley's theorem that calculate the sides XY, YZ and ZX of Morley's triangle. We may now consider calculate area of Morley triangle and observation that, for example, in triangle ABC, length or sides XY, YZ and ZX are $8Rsin{\alpha}sin{\beta}sin{\gamma}$, respectively. Therefore, compare with the area of Morley's triangle XYZ and the area of triangle ABC.