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고속 열 성형 유한요소해석을 활용한 CF/PEKK 열가소성 복합재 구조물 제작 공정 예측 및 검증
이경인 ( Keung-in Lee ),최현석 ( Hyeon-seok Choe ),곽준우 ( June-woo Kwak ),이준성 ( Jun-sung Lee ),주현우 ( Hyun-woo Ju ),권진회 ( Jin-hwe Kweon ),남영우 ( Young-woo Nam ) 한국복합재료학회 2021 Composites research Vol.34 No.5
본 연구에서는 유한요소법(FEM)에 기반한 CF/PEKK 열가소성 복합재 고속 열 성형 해석을 수행하였고 제작 공정을 예측 및 검증하였다. 대표적인 L 형 구조물 모델에 대해 트리밍 여유에 따른 성형성을 응력, 두께, 주름분포를 분석하였다. 그 결과, 블랭크의 트리밍 여유가 증가할수록 구조물의 성형성이 향상하는 것을 확인하였다. 특히 두께 및 주름 분포 측면에서 해석 모델과 실험 결과를 비교하여서 고속 열 성형 모델의 타당성을 검증하였다. 제작된 구조물은 시차 주사 열량 분석법 및 이미지 분석법을 통해 결정화도와 기공률이 측정되었다. 제작된 열가소성 구조물의 전 영역 기공률은 평균 0.75%, 결정화도는 약 21%로 항공기에 적용 가능한 수치로 평가되었다. 따라서 본 연구를 토대로 열가소성 복합재 고속 열 성형 공정에 대해 효과적인 예측이 가능할 것으로 판단된다. This study presented the evaluation of the stamp forming process for L-shape CF/PEKK thermoplastic composite using the finite element model. The formability of three different trimming allowances has been examined for representative product geometry. The results showed that those manufactured by high trimming allowance showed more excellent formability in those areas. Moreover, the effects of the trimming allowances on the stress, thickness, wrinkle distributions of thermoplastic composites fabricated with the stamp forming process were evaluated. The comparison of the simulation and experimental results for the thickness and wrinkle distributions proved the accuracy of the stamp forming model. The crystallinity of the composite was performed by differential scanning calorimetry (DSC). The void content of the composite was evaluated by matrix digestion. Then, the fabricated structure was characterized and achieved high quality in crystallinity and void content. Consequently, the presented FEM modeling shows excellent potential for application in the aircraft product design process. This pragmatic approach could efficiently offer a valuable solution for the thermoplastic composite manufacturing field.
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후천성 면역 결핍증 환자 ( AIDS ) 의 혈액면역학적 특성과 기회감염에 대한 임상적 고찰
남태수(Tae Su Nam),서경수(Keung Su Seo),이경인(Kyong In Lee),김윤성(Yun Seong Kim),홍진희(Jin Hee Hong),김광하(Gwang Ha Kim),정준훈(Joon Hoon Jeong),주형준(Hyung Jun Chu),박승근(Seung Keun Park),성낙현(Nak Hean Seoung),정주섭(Ju Sup 대한내과학회 1997 대한내과학회지 Vol.52 No.1
N/A The number of persons with HIV infection in Korea have increased steadily, total number of HIV infection in Korea were 478 on August, 1995. To investigate the clinicoimmunologic manifestation of AIDS in Korea, we reviewed complete blood counts (CBC), CD4 counts, serum β2-microglobulin level, opportunistic infections and cause of death for 19 AIDS patients who had been admitted or visited at Pusan national university hospital during the period of January, 1990 to August, 1995. 1) The predominant mode of HIV transmission was heterosexual contact(18), other modes of transmission were homosexual contact(1). Clues of diagnosis of HIV infection were routine occupational health examination(14), and opportunistic infection symptoms such as fever, coughing(4). 2) Mean CD4 cell counts(/mm3) were 53±72 totally, 22±27 for 8 dead patients at mean 2 month before, 91±87 for 7 living patients. There were not significant difference(p>0.05). 3) Serum β2-microglobulin(MG;ug/ml) was measured at 12 patients, mean serum β2-MG level was4.8±7.3 totally, 7.1±10.3 for 6 dead patients at mean 1.3 month before, 2.5±0.4 for 6 living patients. There were not significant(p>0.05). 4) At CBC examination, WBC(/mm3) was 5,932±2,899 totally, 5,452±3,436 for 10 dead patients, 6,500 ±2,221 for 9 living patients(p>0.05). Hb(g/dl) was 11,4±2.8 totally, 9.4±1.8 for dead patients, 13.6±1.8 for living patients(p<0.05). Lymphocyte count(/mm) was 1,255±800 totally, 731±424 for dead patients, 1,838716 for living patients(p<0.05). ESR(mm/h) was 72±47 totally, 97±33 for dead patients, 47±47 for living patients(p<0.05). 5) Opportunistic infections had developed at 14 patients, candidiasis 7, pneumocystis carinii pneumonia 5, tuberculosis 3, cytomegalovirus infection 2, herpes zoster 3, toxoplasmosis 1, cryptococcal infection 2, bacterial pneumonia 5, and herpes simplex l. Malignant lymphoma had developed in 1 patient. 6) Mean survival interval from diagnosis of HIV infection to death was 32.8±19.1 months, and the most common cause of death was pneumocystis carinii pneumonia, and other causes of death were meningitis, bacterial pneumonia and AIDS-wasting syndrome. Based on these results, We concluded that CD4 counts, serum β2-microglobulin level, Hb, total lymphocyte count and ESR in AIDS patients are specific laboratory markers of progression and prognosis of AIDS, the most common opportunistic infection was candidiasis, and the most common cause of death in AIDS patients was pneumocystis carinii pneumonia.
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