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브라켓 재생시 표면 처리 방법에 따른 전단 접착 강도에 관한 연구
임장빈,이진우,차경석 대한치과교정학회 1996 대한치과교정학회지 Vol.26 No.5
본 연구는 현재 브라켓의 개발 양상이 tip, torque 등이 브라켓 내에 내재되어 있는 straight wire appliance의 도입으로, 브라켓의 디자인은 더욱 세밀하고, 복잡해져 점차 고가화 되어 재사용의 요구가 증가하는 점에 맞추어 계획되었다. 본 연구의 목적으로는 재생과정의 목표에 부합하는 브라켓 접착면의 재처리 방법을 찾는 것이다. 실험 방법은 금속 브라켓, 도재 브라켓 각 5개씩 5군으로 나누어 브라켓 기저부에 재처리과정을 시행한 후, 이를 치아에 접착하고 만능 시험기(universal testing machine)을 사용하여 치아에서 브라켓이 탈락하는 시점의 최대 전단접착강도를 채득하였으며, 그 후 치아의 법랑질 표면을 입체 현미경으로 관찰하여 파절면의 접착제 잔류지수를 구하였다. 또한 입체 현미경 (stereoscopic microscope)과 주사전자현미경 (SEM) 화상으로 재처리된 브라켓의 접착면을 관찰하였다. 이와 같은 실험으로 다음과 같은 결론을 얻었다. 1. 금속 브라켓에서 접착 강도가 가장 높은 재처리 방법은 sandblasting을 8초간 시행한 군이었으며, 이는 제조회사에서 제작된 원래 상태인 대조군의 접착강도보다도 오히려 높았다. 2. 세라믹 브라켓에서 접착 강도가 높은 재처리 방법은 8초간 sandblasting한 군이었으나, 대조군의 접착강도 보다는 낮았다. 3. Sandblasting 시간을 4초에서 8초로 증가시킨 경우 금속 브라켓의 접착강도는 급격히 증가하는데 비해 도재 브라켓의 접착강도는 별 차이가 없었다. 그 이유는 도재 브라켓의 경우 브라켓 접착부의 표면적 증가에도 불구하고, 금속 브라켓과는 달리 브라켓 자체의 물성 차이로 인해 도재 브라켓에서의 접착력을 좌우하는 거대 기계적 결합부위의 파손이 일어나 접착력의 약화를 가져왔기 때문이다. The purpose of this study is to find the optimal reconditioning method for a debonded bracket base. In this study, metal brackets and ceramic brackets are used. There are devided into five groups by reconditioning methods (A : control(new bracket). B : heat treated, C : grinded with green stone, D : sandblasting for four seconds, E : sandblasting for eight seconds). Each reconditioned brackets were bonded and shear bond strength was measured by universal testing machine. After debonding, enamel surfaces were examined under stereoscopic microscope to determine the adhesive remnant index. The Microstructure of reconditioned bracket were examined by SEM (JSM 5200, Japan) and stereoscopic microscope (SZ-ST, Japan). 1. In metal bracket groups, sandblasting for eight seconds revealed the greatest shear bonding strength and its strength was above that of control group. 2. In ceramic bracket groups, sandblasting for eight seconds revealed the greatest shear bonding strength but its strength was below that of control group. 3. As sandblasting time was increased, shear bonding strength of metal bracket was increased very much, but in ceramic brackets, shear bonding strength exhibited limited increase. This difference was caused by macro-mechanical retentive areas of ceramic brackets were broken for their brittle characteristics of material.
정상화,김현욱,장우양,김경석,차경래,나윤철 朝鮮大學校 機械技術硏究所 2001 機械技術硏究 Vol.4 No.2
최근 전 세계적으로 초소형 정밀 기계 기술에 관한 연구 및 개발이 활발하게 이루어지면서 형상기억합금(Shape Memory Alloy : SMA)을 이용한 초소형 액츄에이터(Micro Actuator)에 관한 관심이 증대되고 있다. 형상기억합금을 액츄에이터에 응용하기 위해서는 동적 특성의 분석이 필수적이지만 지금까지의 연구에서는 형상기억합금의 물질 및 재료적 특성은 많이 보고되고 있으나 동적 특성에 대한 연구는 매우 부족한 실정이다. 본 논문에서는 비저항(resistivity)이 큰 NiTi합금 와이어(wire)를 이용하여 나선형 스프링(helical spring)을 제작하여 디지털 힘 측정기(Digital force gauge)와 적외선 온도센서(Infrared themometer) 그리고 레이저 변위 센서(Laser displacement sensor)를 이용하여 이 NiTi 스프링의 힘의 크기와 반응속도, 온도와 변위를 측정하여 형상기억합금의 동적 특성을 분석하였다. 또한 형상기억합금을 이용하여 차동식 액츄에이터를 제작하여 그 동적 성능을 실험하였다. In the recent years, as the research and the development of micro and precision machinery become active, the interest of micro actuators using SMA(Shape Memory Alloy) has been increased. The dynamic characteristic analysis of SMA is necessary for actuator application and many common researches report the material characteristics of SMA sufficiently. However, the research on dynamic characteristics is very deficient. In this paper, the helical spring are fabricated with NiTi SMA wire of high resistivity. The force, response speed, temperature, and displacement are measured by digital force gauge, infrared thermometer, and laser displacement sensor so that the dynamic characteristics of this SMA is analyzed. Also, bidirectional actuator was fabricated and experimented for its performance.
Ketamine Modulates Calcium Homeostasis in Hypoxia-Reoxygenated Cardiomyocytes
( Jang Ho Roh ),( Woo Chul Chang ),( So Yeon Lim ),( Hee Sang Song ),( Byeong Wook Song ),( Hye Jung Kim ),( Min Ji Cha ),( Yang Soo Jang ),( Nam Sik Chung ),( Yong Woo Hong ),( Ki Chul Hwang ) 한국조직공학·재생의학회 2008 조직공학과 재생의학 Vol.5 No.3
Ketamine is clinically used as an inducer of anesthesia in critically ill patients because it has more stable hemodynamics than barbiturates or inhaled anesthetic agent. It has been known the effect of anesthetic related with calcium homeostasis in myocardium but there are few studies for myocardial protection of ketamine from ischemiareperfusion injury. We therefore observed protective effects of ketamine on survival of ischemia-reoxygenated cardiomyocytes in phosphorylation levels of Erk and Akt as well as suppression of pro-apoptotic protens, Bax and cytochrome C, and induction of anti-apoptotic protein, Bcl-2. Ketamine also overcame intracellular Ca2+ overload. We observed significant induction in transcript level of calreticulin, PMCA1, ion channels(L-type Ca2+-channel, Kir3.4, Kir6.1) and suppression in transcript level of calmodulin, and SERCA 2a in ketamine-treated cardiomyocytes. In conclusion, ketamine was protective of cardiomyocytesunder hypoxia-reperfusion condition. Therefore, we have provided new insight into myocardial protection of anesthetic agents so a better understanding of the role of anesthetics in the prevention of myocardial injury may provide strategies to improve outcome.
Role of corticosterone in ethyl carbamate-induced immunosuppression in female BALB/c mice
Cha, Shin Woo,Lee, Hu Jang,Cho, Myung Haing,Lee, Mun Han,Koh, Woo Suk,Han, Sang-Seop,Kim, Jung-Ae,Lee, Eung-Seok,Nam, Doo-Hyun,Jeong, Tae Cheon 영남대학교 약품개발연구소 2001 영남대학교 약품개발연구소 연구업적집 Vol.11 No.-
We have recently demonstrated that the antibody response to the T-cell-dependent antigen, sheep red blood cells(SRBCs), was suppressed by ethyl carbamate in female BALB/c mice. At the same doses, ethyl carbamate decreased in the numbers of splenic macrophages. B cells, total T cells, CD4^(+) T cells and CD8^(+) T cells. In addition, the serum level of corticosterone was increased dose-dependently. To investigate the possible role of corticosterone in ethylcarbamate-induced immunosuppression, the antibody response to SRBCs and the subpopulation changes of splenocytes and thymocytes were determined in naive, sham-operated and adrenalectomized (ADX) female BALB/c mice. When the mice were treated intraperitoneally with 400 mg/kg ethyl carbamate, the antibody response was significantly suppressed by ethyl carbamated in naive and sham-operated mice in accompanying the decrease in spleen and thymus weights and/or the increase in the level of serum corticosterone. Meanwhile, the antibody response was not suppressed by ethyl carbamate in the ADX mice. The splenic numbers of total cells, macrophages B and T cells, and CD4^(+) cells were decreased by ethyl carbamate in naive and sham-operated mice. Meanwhile, each cell number was comparable with control in the ADX mice. The flow cytometric analyses on thymocytes did not show obvious differences as seen in the spleen. Finally, when the ADX mice were treated intraperitoneally with 25 mg/kg corticosterone, the antibody response was significantly suppressed. Taken together, our present results suggested that corticosterone might be, at least partially, responsible for ethy; carbamate-induced immunosuppression in female BALB/c mice. ⓒ 2001 Elsevier Science Ireland Ltd. All rights reserved.
화이트소스를 첨가한 굴(Crassostrea gigas) 통조림의 제조 및 특성
차장우 ( Jang Woo Cha ),이수광 ( Su Gwang Lee ),박선영 ( Sun Young Park ),강상인 ( Sang In Kang ),강영미 ( Young Mi Kang ),김진수 ( Jin-soo Kim ) 한국수산과학회(구 한국수산학회) 2018 한국수산과학회지 Vol.51 No.5
The objective of this study was to investigate the composition of canned oyster Crassotrea gigas in white sauce (CO-WS). The proximate composition of CO-WS was 74.1% water, 10.4% crude protein, 4.9% crude lipid, and 3.1% ash. The energy converted based on these percentages was 112.2 kcal/100 g, while the salinity was 1.1 g/100 g. In a taste-intensity test using an electronic tongue, the CO-WS showed higher umami taste intensity than the control (canned oyster in commercial white sauce), whereas the intensities of the other tastes (salty, sour, bitter, and sweet) were lower. Because the odor intensity was low, CO-WS was considered to have a relatively weak odor and showed no difference in hardness compared to the control. Sensory evaluation of CO-WS by a panel yielded higher scores for appearance, taste, and texture, and a lower score for flavor compared to the control. The total amino acid content of CO-WS was 8.91 g/100 g, and its major amino acids were aspartic acid, glutamic acid, and leucine. With respect to mineral content, CO-WS had higher calcium and lower zinc contents than the control. These results suggest that CO-WS has excellent nutritional value.