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한창환,김근택,이종원,최윤호,Han, Chang-Whan,Kim, Keun-Taek,Lee, Jong-Won,Choi, Youn-Ho 한국항공우주연구원 2002 항공우주기술 Vol.1 No.2
본 연구는 탄소섬유 복합재료 사각튜브의 압축 에너지 흡수 특성을 실험적으로 규명하였으며, 유한요소해석을 통해서 그 특성을 예측하였다. 압축 속도는 0.003mm/sec 와 0.3mm/sec로 하여 사각튜브에 가하였으며, 적층각 별로 실험을 하여 각각에 대한 압축 에너지 흡수 특성인 최대 압축하중과 평균하중을 찾았다. [0/90]₄와 [0/±45/90]₂의 특정 적층각을 가지는 사각튜브에 대해 유한요소해석을 수행하여 최대 압축하중을 예측하였다. 유한요소모델은 좌굴해석을 통해서 나온 형상과 원래 형상을 중첩하였으며, 해석방법은 Tsai-Wu criteria를 사용하였다. 실험으로부터 최대 압축하중은 인 사각튜브에서 나타났고 평균 압축하중은에서 나타났으며, 특정각을 가지는 사각튜브에 대한 최대 압축하중 예측은 실험과 거의 일치하였다. Crush energy characteristics of graphite/epoxy square tubes are experimentally studied. Effect of the ply orientation on the peak load and the average load is investigated by applying compressive load on the top of the composite square tubes under the stroke control with crosshead speed of 0.003mm/sec and 0.3mm/sec. in addition to the experimental survey, the finite element analysis is used to estimate the peak load of the composite square tubes with [0/90]₄ and [0/±45/90]₂. The first buckling mode of the tube is superimposed to the perfect geometry and the distributed compressive load is applied on the top of the tubes. The applied compressive load that make Tsai-Wu criteria equal to one is regarded as the peak load of the tubes. The experimental data shows that the square tube with [45/-45]₄ has the highest peak load and the square tube with [60/-60]₄ has the average sustained load. The measure peak load of the composite tubes with [0/90]₄ and [0/±45/90]₂agree well with the estimated peak load using the finite element analysis.
일산화질소에 의해 유도된 연골 세포 사멸에서의 항세포사멸유전자 Bcl-XL의 방어 효과
한창환 ( Chang Whan Han ),신윤학 ( Yun Hak Shin ),권순용 ( Soon Yong Kwon ),조윤경 ( Yun Kyoung Cho ),지보근 ( Bo Keun Jee ),김영율 ( Young Yul Kim ),김순희 ( Soon Hee Kim ),박기숙 ( Ki Sook Park ),강길선 ( Gil Son Khang ) 한국조직공학과 재생의학회 2005 조직공학과 재생의학 Vol.2 No.2
To evaluate whether transfection of human chondrocytes with an anti-apoptotic gene, Bcl-XL, can prevent nitric oxide (NO)-induced chondrocyte apoptosis. We stably transduced early passage chondrocytes with an anti- apoptotic gene Bcl-XL and retrovirus. Bcl-XL transducants were compared with chondrocytes transduced in parallel with a Lac-Z gene. After the cells were treated with 500 microM of SNP, the process of apoptosis was assessed by trypan blue exclusion, enzyme-linked immunosorbent assay (ELISA), and flow cytometry. The functional aspect of the chondrocyte was measured by proteoglycan synthesis assay. Chondrocytes were cultivated in NO, the chondrocytes that were either not transfected or transfected with Lac-Z exhibited a decrease in viable cell number in comparison to the Bcl-XL transfected chondrocytes. The NO significantly increased fragmentation of DNA in chondrocytes that were either not transfected or transfected with Lac-Z, and this increase in DNA fragmentation was significantly greater than in the chondrocytes transfected with Bcl-XL. Flow cytometric result showed that apoptotic chondrocytes were significantly higher in the transfected and Lac-Z transfected chondrocytes than Bcl-XL transfected chondrocytes. Chondrocytes transfected with Bcl-XL were protected from NO-induced impairment of proteoglycan synthesis response to NO. From the present study, we have demonstrate that NO-induced chondrocytes death involve mechanisms subjected to regulation by an anti-apoptotic protein, Bcl-XL. Therefore, Bcl-XL gene therapy has the potential to protect apoptosis in human chondrocyte.
요추부 추간판 탈출 환자들에서 저산소 유도 인자-1а와 세포사멸
한창환 ( Chang Whan Han ),권순용 ( Soon Yong Kwon ),조윤경 ( Yun Kyoung Cho ),지보근 ( Bo Keun Jee ),김영율 ( Young Yul Kim ),김순희 ( Soon Hee Kim ),강길선 ( Gil Son Khang ) 한국조직공학과 재생의학회 2004 조직공학과 재생의학 Vol.1 No.2
To analyze the expression of a hypoxia inducible factor (HIF)-1а and apoptosis in herniated lumbar discs. 12 human intervertebral discs (IVD) from surgery for lumber disc herniation (LDH) were stained for HIF-1а immunohistochemically and apoptosis through TUNEL method. The patients were on average 35.9 years old. The cases were divided into non-contained (NC: 6 cases) and contained (C: 6 cases) groups. For the control group, IVD from 2 cases of adolescent idiopathic scoliosis (AIS) and 2 of bursting fracture were used. Expression of HIF-1а was visualized in every case, with an average of 65.2±9.5% of the disc cells in the NC group, 33.5±3.6% in the C group, and 13.4±9.7% in the control. Apoptosis occurred in 77.3±7.3% of the cells in the NC group, 45.8±5.5% of C group, and 26.8±8.4% of the control. HIF-1а and apoptosis expressions were both observed more frequently in the LDH groups, and the NC group showed greater expression.(P<0.001) In correlation analysis, the relationship between the degree of HIF-1а expression and apoptosis showed statistically significant correlation. HIF-1а and apoptosis occur physiologically in human IVD. Their expression was the greatest among the NC group.