http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
후기 경화조건이 DGEBA / MDA / SN 계의 절연파괴특성에 미치는 영향
조영신,심미자,김상욱 ( Y . S . Cho,M . J . Shim,S . W . Kim ) 한국공업화학회 1995 공업화학 Vol.6 No.5
후기 경화조건이 열경화성 에폭시 수지 DGEBA/MDA/SN 계의 절연파괴 특성에 미치는 영향에 대하여 조사하기 위하여 80℃에서 1.5시간 동안 1차 경화시킨 후 130℃와 150℃에서 후기 경화시간을 달리하여 경화시켜 전극간 거리가 1㎜되게 시편을 제작하였다. 각각의 시편에 고전계를 인가하여 절연파괴강도를 측정하고 절연파괴 형상을 관찰하여 절연파괴 메카니즘에 대한 해석을 시도하였다. 후기 경화시간이 증가함에 따라 밀도는 1.2 [g/㎤] 정도에서 미소 증가하였으며, 유리 전이온도(T_g)는 9시간 후기 경화시켰을 때 111℃로 최고 값을 나타내었다. 절연파괴강도(E_B)는 증가하다가 5시간 후기 경화되었을 때 25.7[㎸/㎜]로 최고 값을 나타내었다. 그러나 그 이상 경화되었을 때는 열 열화에 의해 오히려 감소되었다. 초기 트리는 후기 경화조건에 관계없이 고전압에서는 가지밀도가 낮았으며 저전압에서는 가지밀도가 높았다. Investigated were the effects of post-curing conditions on the dielectric breakdown properties of thermoset DGEBA/MDA/SN system. The epoxy resin system with electrode gap of 1㎜ was first-cured at 80℃ for 1.5hr and post-cured at 130[℃] and 150[℃] respectively for various time periods. As the post-curing time increased, the density increased slightly from 1.2 [g/㎤] and glass transition temperature(T_g) was the highest value of 111℃ when post-cured for 9hr. Dielectric breakdown strength(E_B) increased to 25.7[㎸/㎜] and then decreased. The initial tree grown at lower voltage was more dense than the tree grown at higher voltage.
DGEBA - MDA - Nitrile System 의 금속 계면에서의 전기현상
조영신,심미자,김상욱 ( Y . S . Cho,M . J . Shim,S . W . Kim ) 한국공업화학회 1995 공업화학 Vol.6 No.4
DGEBA(diglycidyl ether of bisphenol A)-MDA(4,4`-methylene dianiline)에서 SN(succinonitrile) 첨가에 따른 침전극 계면에서의 전기적 현상을 고찰하였다. 국부적 고전계하에 발생한 고온으로 변색된 영역은 트리(tree)개시의 선결조건이며, 이 지역에서는 미반응된 작용기가 재배열되고 경화반응이 더 진척되었다. 또한 반응성 첨가제 SN의 함량이 증가함에 따라 절연파괴전압은 감소하다가 25㎸로 포화되었으며, 관찰된 트리는 dendrite상이었다. The electrical phenomena at the interface of cured DGEBA(diglycidyl ether of bisphenol A)-MDA(4,4`-methylene dianiline)-SN(succinonitrile) system and needle electrode were investigated. At the discolored region around the needle, which should be formed before the tree initiation, unreacted functional group was rearranged and curing reaction was proceeded under the regional high electric field. As SN contents were increased, the dielectric breakdown voltage was decreased and saturated at 25㎸. The shape of the tree in this system was a dendrite type.
교류 고전계하에서 DGEBA - MDA - SN 계의 흡수열화에 따른 절연파괴 특성
조영신,심미자,김상욱 ( Y . S . Cho,M . J . Shim,S . W . Kim ) 한국공업화학회 1995 공업화학 Vol.6 No.5
DGEBA-MDA-SN 계의 흡수열화에 따른 교류 단시간 절연파괴 메카니즘에 대한 해석을 시도하였다. 흡수열화가 진행됨에 따라 재료 내부에 크랙이 발생, 성장하였으며 침전극과 수지계 계면에서는 박리현상이 관찰되었다. 그리고 유리 전이온도는 감소하다가 강제흡수주기가 3 이상에서는 다시 증가하였으며 절연 파괴강도의 감소와는 일치되지 않는 결과를 나타내었다. 흡수열화에 따른 전기적 성질의 열화는 주로 물리적 성질의 변화에 크게 영향을 받으며 화학적 조성변화, 기계적 성질변화 등 다양한 제반성질의 변화에 대한 관찰을 통하여 해석이 가능하다. The deterioration mechanisms by water absorbing in DGEBA-MDA-SN system at AC high electric field were studied. Microscopic observations indicated the internal crack growth in the resin system and delamination around the needle electrode during forced water absorbing deterioration. The crack growth mainly depended upon the number of heat cycle in water bath. The changes in the glass transition temperature of the materials showed less correlation with the decreases in electrical properties and it was difficult to find out the changes of the chemical structures with FT-IR spectrum analysis. The results showed the physical structure changes such as the crack growth in DGEBA-MDA-SN system deteriorated the electrical properties of the materials.
박유환(Y .H .Park),정춘혜(C .H .Chung),조영신(Y .S .Cho),김동규(D .G .Kim),손현화(H .H .Son),서영선(Y .S .Seo),이미자(M .J .Lee) 대한내과학회 2000 대한내과학회지 Vol.58 No.5
Background : The role of oncogenes and tumor suppressor genes in the pathogenesis of gastric carcinoma has recently received considerable attention. The tumor suppressor gene, p53 locus on chromosome 17p, ceases a mitosis in G1/S check point after DNA demage. Abnormality of the p53 tumor suppressor gene plays an important role in alteration of cells and possibly leads to cancer development. The authors investigated the correlation between expression of p53 and prognosis in advanced gastric carcinoma. Methods : Expression of tumor suppresor gene p53 was investigated immunohistochemically in the primary lesion of 34 patients with advanced gastric carcinoma using paraffin embedded surgical specimens and the relationship of p53 immunopositivity with the clinicopathologic variables(Age, Sex, TNM staging, Lauren classification, Borrmann classification), 5-year survivals and life curves were analyzed. Kaplan and Meier's method is used as a life curve and log crank method is used for the analysis of prognostic factor. Results : Total p53 positive rate was 53% (18 of 34) of all cases. p53 immunopositivity was not associated with other clinicopathologic variables. The 5-year survivals were 44% and 11% for patients with p53 negative and positive gastric carcinomas, respectively. Patents with the expression of p53 has predominantly poor results in comparison of life curve(p<0.05) Conclusion : These findings suggest that p53 gene alteration be associated with poor prognosis of advanced gastric adenocarcinoma(Korean J Med 58:568-574, 2000)
나이트릴로 개질된 에폭시 수지계의 절연파괴에 미치는 공간전하의 효과
김상욱,조영신,심미자,송영욱 한국공업화학회 1998 응용화학 Vol.2 No.1
The effects of space charge on dielectric breakdown phenomena in the epoxy resin system DGEBA/MDA modified with GN was observed. As the temperature increased the dielectric breakdown strength decreased rapidly at higher than HDT. At high temperature the electron was emitted and flew further than low temperature, easily. The emitted electron from the magnified electrode tip flew through the polymeric chain, trapped deep inside and formed space charge. The space charge distorted the electric field and concentrated it on the weakest point and decreased electrical properties. The eroded surface of tree channel by thermal electron emitted was detected.