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서명기,한근호,조영훈,이관영 한국공업화학회 2016 한국공업화학회 연구논문 초록집 Vol.2016 No.1
Direct synthesis of H<sub>2</sub>O<sub>2</sub> is a simple and efficient process. When introducing the catalyst with the core-shell structure, the sintering of Pd metal was suppressed in the calcination, and a catalyst having a highly Pd dispersion was synthesized. Moreover, the physical detaching of Pd nanoparticle was inhabited in the synthetic reaction of H<sub>2</sub>O<sub>2</sub>. However, core-shell catalyst is not easy to control the thickness and pore size of the shell. It is necessary to increase the pore size for proper mass transfer. In this study, the catalyst with Pd/SiO<sub>2</sub> nanoparticles coated with silica shell was introduced to easily control the shell thickness and pore size. In particular, the pore size of the shell was increased by adding a surfactant when synthesizing the shell. The hydrogen peroxide production rate was increased by adjusting the shell thickness and thereby synthesizing the nanocatalyst having an optimal shell thickness.
$La(Zn_{1/2}Ti_{1/2})O_3$의 합성 및 고주파 유전특성
서명기,조서용,홍국선,박순자 한국세라믹학회 1996 한국세라믹학회지 Vol.33 No.9
The dielectric properties at microwave frequencies of B site complex perovskite La(Zn1/2Ti1/2)O3 which has +3 ion in A site were investigated. maximum Q*F value of the specimens was 59000 dielectric constant 34, temperature coefficient of resonant frequency -52 ppm/$^{\circ}C$. XRD pattern of the sintered specimen shows (111) ssuperlattice reflection which indicates Zn and Ti cation ordering.
서명기,이대원,정하은,이관영 한국공업화학회 2015 한국공업화학회 연구논문 초록집 Vol.2015 No.0
과산화수소는 화학물질의 산화제로 많이 쓰이지만, 현재의 과산화수소를 생산하는 상용공정은 anthraquinone을 사용하는 공정으로 매우 유독한 공정이다. 이를 대체하기 위해 수소와 산소로부터 과산화수소를 생산하는 직접 생산공정이 연구되고 있으나, 낮은 수율로 인하여 상용화 단계에는 도달하지 못하고 있다. 우리의 예전 결과에서 수소와 산소로부터 과산화수소를 생산하는 공정에 Pd@SiO2촉매를 도입할 경우 일반적인 담지 촉매인 Pd/SiO2보다 높은 과산화수소 선택도 및 수율을 얻는 것을 확인하였다. 이 연구에서는 우리의 기존 연구를 확장하여 shell의 acid site가 반응에 미치는 영향에 대하여 연구하였다. 특히, Shell의 산점(Brønsted 및 Lewis)을 갖는 shell은 아직까지 보고된바 없으며, 우리는 stober 방법을 응용하여 실리카-알루미나를 shell로 갖는 촉매를 처음으로 도입 하였다. Shell에 함유된 acid site가 용매에 첨가하는 인산과 비슷한 역할을 하는것을 실험으로 관찰하였다. 특히, shell의 산점 및 용매에 첨가하는 인산에 의해서 Pd의 Br흡착량이 증가하고, 이에 따라 과산화수소의 선택도가 증가하는 것을 확인하였다.
64열 다중검출 CT를 이용한 관상동맥 스텐트재협착의 평가
서명기 ( Myung Ki Seo ),고진신 ( Jin Shin Kho ),박소라 ( So Ra Park ),강영란 ( Young Ran Kwang ),강민경 ( Min Kyeng Kang ),조정현 ( Jung Hyun Cho ),안연정 ( Youn Jung An ),최봉룡 ( Bong Ryong Choi ),정영훈 ( Young Hoon Jeong ) 대한내과학회 2009 대한내과학회지 Vol.76 No.4
Background/Aims: Multidetector computed tomography (MDCT) is considered to be a noninvasive, alternative method for evaluating stent restenosis. However, the diagnostic accuracy of 16-channel MDCT for stent stenosis is reported to have severe limitations because of high-attenuation stent-related artifacts. 64-channel MDCT, which recently became available in clinical practice, has better spatial and temporal resolution than 16-channel MDCT. The diagnostic accuracy of 64-channel MDCT for stent restenosis (in-segment and in-stent) was assessed by comparing it with conventional coronary angiography. Methods: In-segment and in-stent restenosis (≥50% in diameter) were evaluated in 96 stent segments in 68 patients [61±12 years, 51 (75%) male] using both 64-channel MDCT and conventional coronary angiography. The in-stent analysis was confined to the portion of the artery covered by the stent and the in-segment analysis included the stent and 5 mm proximal or distal to the stent edges. Results: The 64-channel MDCT could evaluate stent restenosis in 93 of 96 (97%) stent segments. Quantitative conventional coronary angiography found in-segment restenosis (≥50% in diameter) in 16 of 68 (23%) patients and 16 of 96 (17%) segments. For the patients with interpretable stent segments, the sensitivity, specificity, positive predictive value, and negative predictive value of 64-channel MDCT for in-segment restenosis per patient were 63, 96, 83, and 89%, respectively; per segment they were 63, 97, 83, and 93%, respectively; and for in-stent restenosis per stent they were 82, 98, 82, and 98%, respectively. Conclusions: The diagnostic accuracy of 64-channel MDCT for assessing stent restenosis had high specificity and negative predictive value in the clinical setting. The 64-channel MDCT may be a promising, less-invasive imaging tool for stent restenosis, especially for the purpose of excluding stent restenosis. (Korean J Med 76:434-442, 2009)