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Ge ( OCH3 )4 의 화학증착에 의한 HZSM - 5 촉매의 형상선택성에 관한 연구
문세기,김형진,김문혁,손영순 ( Sei Ki Moon,Hyung Jin Kim,Moon Hyuck Kim,Young Soon Sohn ) 한국화학공학회 1992 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.30 No.1
Germanium methoxide was deposited irreversively by CVD(chemical vapor deposition) on the zeolite(HZSM-5) under 2×10^(-3) torr and at 300℃, and the deposited materials were calcined at 400℃ in air, finally forming germanium oxide-deposited zeolites(GeHZSM-5). These were characterized by temperature-programmed desorption of ammonia, FT-IR analysis and adsorption experiments using water, p-xylene and o-xylene as adsorbates. It was suggested that the germanium oxide was deposited only on the external surface of the catalysts and narrowed the pore-opening size effectively without changing the internal structure and the acidity of the catalysts. The fine control of pore-opening size was tested by alkylation of toluene with methanol. Hydrocarbon product distribution shifted to smaller molecules over GeHZSM-5 than HZSM-5 catalyst; that is, the yields of m-, o-xylenes were decreased, but the yield of p-xylene was increased. Enhancement of the para-shape selectivity in xylene isomers indicated the fine control of the pore-opening size according to the deposition extent.
방사선 사진을 이용한 계수 영상의 판독능에 관한 실험적 연구
나경수,조봉혜,손영순 大韓口腔顎顔面 放射線學會 1994 Imaging Science in Dentistry Vol.24 No.2
The comparative detectability of the artificial defects among conventional radiographs, digital images and digital subtraction images was evaluated. The artificial defects were made within spogy bone of 24 unilateral mandibles of adult dogs. The results were as follows: 1. With normal exposure time, the detectability of digital subtraction radiographs was 90.3% which was statistically significant superior to those of conventional radiographs(78.0%) and digital images(75.9%)(p<0.05). 2. With half-exposure time, the detectability of conventional radiographs, digital images and digital subtraction radiographs was 68.4%, 67.3% and 69.9% respectively. There was no statistical significant difference among the detectability of these methods(p>0.05). 3. All radiographic images with normal exposure time showed statistically significant superior detectability to those with half-exposure time(p<0.05). 4. The detectability of digital subtraction radiographs was not linearly related to the standard deviation of the grey levels of reference line(p<0.05).
규격화 및 개인별 악관절사측방향 투사법에 관한 비교연구
손영순,나경수 大韓口腔顎顔面 放射線學會 1992 Imaging Science in Dentistry Vol.22 No.1
The author obtained 120 oblique-lateral transcranial radiograms by two projection methods from 30 subjects with clinically normal TMJ. The relative position of the condyle within the articular fossa and the quality of the radiographic images were compared in the standardized and individualized radiographic groups. The results were as follows: 1. The condylar position in the individualized radiographic group was more posterior than that in the standardized radiographic group(P<0.001). 2. The horizontal angle between the long axis of condyle and intermeatal line in the individualized group ranged from 0°to 31°(14.38°± 7.55°), and the highest prevalence was found between 15°and 19°. 3. The individualized group showed prominent radiopaque shadow of the anterior condylar border; the image detail was superior in the standardized group to that of the individualized group(p<0.05).