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HA-coated Zirconia의 생물학적 활성도에 관한 연구
남석우,김해원,김현이,양승민,신승윤,이용무,정종평,한수부,최상묵,류인철,Nam, Suk-Woo,Kim, Hae-Won,Kim, Hyoun-Ee,Yang, Seung-Min,Shin, Seung-Youn,Lee, Yong-Moo,Chung, Chong-Pyoung,Han, Soo-Boo,Choi, Sang-Mook,Rhyu, In-Chul 대한치주과학회 2003 Journal of Periodontal & Implant Science Vol.33 No.1
Hydroxyapatite(HA) has been extensively used as bone graft materials and tooth implant surface coating materials because of its biocompatibility and osteoconductive properties. However, as HA is intrinsically poor in mechanical properties, zirconia($ZrO_2$) was incorporated with HA as reinforcing phases for improvement of mechanical properties. The purpose of this study was to investigate the biological activities of HA-coated zirconia through the cell proliferation test, measurements of alkaline phosphatase activity, and histologic examination. Four kinds of tested blocks were prepared according to the pore size (300-500${\mu}m$/500-700${\mu}m$) and the porosity (70%/90%). Cell proliferation and alkaline phosphatase activity was measured at 1, 7, 14 days. The number of cells proliferate after 7, 14 days were significantly increased in all groups when compared with that of the first day, but there was no significant difference between the 4 groups at each time period. At the 7 day, alkaline phosphatase activities of cells cultured in 4 groups were higher than that of the first day, but there was no significant difference between the 4 groups at each time period. The human gingival fibroblast and MG 63 cell was used to evaluate the cell cytotoxicity using MTT test. The materials tested in the current study turned out to be non-cytotoxic. In histologic examination(SEM), at 1 day there were many cells attached on the surfaces of all kinds of tested blocks. The number of cells were increased over time. At the 14 day, there were more cells proliferated than 1 day and some of the pores of blocks were partially filled with the proliferated cells. The in vitro response of osteoblast-like cells to the HA-coated zirconia showed comparable effect on transformation comparable to hydroxyapatite.
소형 용융탄산염 연료전지 스택의 운전 특성 1 : 100w 급 십자흐름형 스택의 운전 특성
남석우,임태훈,오인환,이갑수,윤성필,홍성안,임희천,이창우,선양국 ( Suk Woo Nam,Tae Hoon Lim,In Hwan Oh,Kab Soo Lee,Seong Pil Yoon,Seong Ahn Hong,Hee Chun Lim,Chang Woo Lee,Yang Kook Sun ) 한국화학공학회 1995 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.33 No.5
A 100W-class stack consisting of ten molten carbonate fuel cells has been fabricated and tested to establish the basic technology for an internally manifolded stack. Each cell in the stack had an effective electrode area of 100 ㎠, and reactant gases were distributed in each cell in a cross-flow configuration. Performance of the stack was investigated as a function of gas utilization, gas composition and temperature using a specially designed stack test apparatus. It was possible to have a stack with an output of more than 100W using an anode gas of 72%H₂/18%CO₂/10%H₂O and a cathode gas of 33%O₂/67%CO₂. The open circuit voltage of the stack was 11.2V and the voltage at a current density of 150 ㎃/㎠ and gas utilization of 0.4 was 7.3V. The voltage loss due to the internal resistance and the electrode polarization, however, was higher than that of a single cell, and the distribution of cell voltages was not uniform indicating that differences in stacking and operating environment of each cell have to be minimized to enhance the cell performance and uniformity. Since the performance degradation of the stack during the continuous operation at 150 ㎃/㎠ was higher than that of the single cell, further works are required to enhance the life of the stack.
남석우,Nam, Seok-U 한국LP가스공업협회 2006 LP가스 Vol.101 No.-
"사업환경이 시시각각으로 급변하고 있고 풀어야 할 과제들이 산적해 있기에 2006년도 역시 다른 때와 마찬가지로 매우 중요한 시기라고 생각되며, 협회가 앞장서서 열심히 업무를 추진할 수 있도록 사업자 여러분들의 적극적인 참여와 관심, 협조를 부탁드립니다."
슬러리 코팅법에 의한 스테인레스 스틸 표면에서의 알루미늄 확산막 제조 및 용융탄산염 내에서의 내식 특성 연구
남석우,황응림,아나톨리 마가뉵,홍명자,임태훈,오인환,홍성안,Nam S. W.,Hwang E. R.,Magtanyuk A. P.,Hong M. Z.,Lim T. H.,Oh I. -H.,Hong S. -A. 한국전기화학회 2000 한국전기화학회지 Vol.3 No.3
용융탄산염 연료전지의 분리판 재료로 사용되는 스테인레스 스틸은 고온 용융탄산염 분위기에서 부식이 심각하여 일반적으로 표면에 알루미늄 확산막을 코팅함으로써 내식성을 향상시켜 사용하고 있다. 본 연구에서는 기존 방법에 비해 보다 경제적인 슬러리 페인팅 및 열처리에 의한 알루미늄 확산막 형성 방법을 고안하여, 스테인레스 스틸 시편 표면에 알루미늄 확산막을 코팅하고, 산화 분위기의 용융탄산염에서 부식 실험을 수행하였다. $650\~800^{\circ}C$에서 제작된 알루미늄 확산막의 두께는 $25\~80{\mu}m$였으며, 열처리 온도가 높고 열처리 시간이 증가할 수록 알루미늄 확산막의 두께가 증가하였다. 부식 실험 결과 스테인레스 스틸 316L의 용융탄산염에 대한 내식성은 알루미늄 확산막을 표면에 형성시킴으로써 크게 향상되었음을 확인하였다. 또한 분극 실험 결과 슬러리 페인팅 및 열처리 방법에 의하여 알루미늄 확산막이 형성된 시편은 기존의 IVD 및 열처리 방법에 의해 알루미늄 확산막이 제작된 시편과 유사하게 안정한 부동태 피막을 형성함으로써 스테인레스 스틸 316L의 부식을 효과적으로 억제시킴을 알 수 있었다. A stainless steel separator for a molten carbonate fuel cell is usually coated with aluminum diffusive layer to protect its surface against corrosion by the molten carbonate at high temperatures. In this study, a relatively simple method was devised to form the aluminum diffusive layer on a stainless steel substrate. Slurry coating of aluminum on the substrate followed by heat treatment under reducing atmosphere at $650\~800^{\circ}C$ produced the aluminum diffusive layer of $25\~80{\mu}m$ thickness. The thickness of aluminum diffusive layer increased with increasing the temperature or duration of the heat-treatment. The corrosion resistance against molten carbonate under oxidizing atmosphere was significantly improved by aluminum diffusive layer formed by the sluny painting and heat treatment method. Moreover, the sample prepared in this study showed corrosion behavior similar to the sample with aluminum diffusive layer prepared by ion vapor deposition and heat treatment.
소형 용융탄산염 연료전지 스택의 운전 특성 2 : 200W 급 같은방향흐름형 스택의 운전 특성
남석우,이갑수,임태훈,오인환,홍성안,임희천,강인준 ( Suk Woo Nam,Kab Soo Lee,Tae Hoon Lim,In Hwan Oh,Seong Ahn Hong,Hee Chun Lim,In Jun Kang ) 한국화학공학회 1996 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.34 No.5
A 200W-class stack consisting of twenty molten carbonate fuel cells has been fabricated and tested to establish the basic technology for an internally manifolded stack. Each cell in the stack had an effective electrode area of 100 ㎠ and reactant gases were distributed in each cell in a co-flow configuration. The stack showed state-of-the-art performance; the stack voltage at a current density of 150 ㎃/㎠ and gas utilization of 0.4 was 16.9 V producing an output of more than 250W using an anode gas of 72%H₂/18%CO₂/10%H₂O and a cathode gas of 70%air/3%CO₂. Compared with the performance of the previously-tested stack, the voltage lass due to the internal resistance and the electrode polarization became lower and the distribution of cell voltages became more uniform indicating that some improvements were made in component fabrication and cell stacking technology. The voltage of the stack, however, decayed during the continuous operation at 150㎃/㎠ and further works are required to enhance the life of the stack.
남석우,오해석,Nam, Seok-Woo,Oh, Hea-Seok 한국정보처리학회 2003 정보처리학회논문지B Vol.10 No.6
본 연구는 동영상으로부터 내용기반 검색을 위하여 동영상의 연속된 프레임간의 영상의 내용 변화를 찾아내어 프레임의 시간정보와 번호판 프레임 영상을 통하여 얻어진 정보를 데이터베이스화하여 검색하는 시스템을 제안한다. 얻어진 동영상을 배경프레임과 처리프레임의 비교영역의 영상의 특징정보를 비교하여 원하는 프레임을 찾는다. 차량의 통과 시간과 차량의 번호판 프레임을 자동으로 추출하여 동영상을 내용과 함께 저장하여 원하는 차량의 동영상 부분을 보여주는 웹에서의 검색시스템이다. 이는 교통정보를 구축 동영상이 포함하고 있는 내용 즉 통과 차량의 정보를 제공할 수 있게 된다. Recent years, as a rapid development of multimedia technology, video database system to retrieve video data efficiently seems to core technology in the oriented society. This thesis describes an efficient automatic frame detection and location method for content based retrieval of video. Frame extraction part is consist of incoming / outgoing car frame extraction and car number frame extraction stage. We gain star/end time of car video also car number frames. Frames are selected at fixed time interval from video and key frames are selected by color scale histogram and edge operation method. Car frame recognized can be searched by content based retrieval method.