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제작공법을 달리한 탄소섬유/에폭시 복합재의 기공함유율 평가 기법
윤성호(Sungho Yoon),장정근(Jungkeun Jang) 한국추진공학회 2017 한국추진공학회지 Vol.21 No.2
In this study, the procedures for quantitative measurement of void contents of carbon fiber/epoxy composites were suggested. Two types of the composites were considered: autoclave cured composite and filament wound composite. Void contents of the composites were evaluated by the density of the composites and their constituents, which was determined from weights in the air and water, and the weight fraction and volume fraction of the constituents obtained from the digestion method and combustion method. The surfaces of filtered carbon fibers were examined by FE-SEM in order to investigate the validity of resin removal from the composites. According to the results, the resin in the composites could be fully removed by the digestion method and combustion method. Therefore, the weight fraction and volume fraction of the constituents, and void content of the composites could be quantitatively obtained by the suggested procedures.
국내 민주화운동 기념단체의 연대강화를 통한 국민화합방안
윤성호(Yoon, Sungho) 조선대학교 민주평화연구원 2019 민주평화연구 Vol.2 No.1
This paper aims to introduce some policies for strengthening the solidarity of local governments and commemoration businesses of democracy, which are creating the provincial commission on human rights, the system of sharing the graduate-school courses of South-North Korea, and the international democracy-human rights-peace organization. After June 10 struggle, 1987, Korea has developed into one of the most democratized countries with its large scale of economy. However, the high speed and intensity of industrialization and democratization have given Koreans a serious division effect between the conservative and progressive parties. The policies above are expected to decrease the groundless and needless segregation of the Korean people, including the North Korea. The idea is tangible and reasonable because the municipal ordinances related to the commemorative business of democratization have the solidarity of the same groups in Korea.
마이크로캡슐이 폴리머 수지의 기계적 특성 및 열안정성에 미치는 영향
윤성호 ( Sungho Yoon ),김민식 ( Minsik Kim ),장세용 ( Seyong Jang ) 한국복합재료학회 2015 Composites research Vol.28 No.5
본 연구에서는 자가치료용 마이크로캡슐이 함유된 복합재의 경우 함유된 마이크로캡슐이 복합재의 기계적 특성과 열안정성에 미치는 영향을 실험적으로 고찰하였다. 이를 위해 melamine-urea-formaldehyde(M-U-F) 박막을 갖는 70~130 μm 직경의 마이크로캡슐들이 함유된 인장시편과 굽힘시편을 에폭시 수지와 폴리에스터 수지로 제작하였다. 이때 마이크로캡슐의 함유량은 0 wt%, 0.5 wt%, 1.0 wt%이다. 인장시험과 굽힘시험을 통해 마이크로캡슐이 함유된 수지시편의 기계적 특성을 평가하였으며 열중량 분석시험을 통해 마이크로캡슐이 함유된 수지 시편의 열안정성을 평가하였다. 연구결과에 따르면 인장탄성계수는 마이크로캡슐의 함유에 큰 영향을 받지 않지만 인장강도는 인장탄성계수에 비해 마이크로캡슐의 함유에 민감하게 나타났다. 그러나 인장강도의 저하는 마이크로캡슐의 함유량에 선형적으로 비례하지는 않았으며 굽힘시험의 결과에서도 유사한 양상이 관찰되었다. 또한 온도 변화에 따른 마이크로캡슐이 함유된 수지시편의 무게 변화는 마이크로캡슐이 함유되지 않은 수지시편의 경우와 유사하여 마이크로캡슐을 수지에 함유시키더라도 열안정성에는 큰 영향이 없음을 알 수 있었다. This study investigated the effects of microcapsules on mechanical properties and thermal stability of the composite material containing self-healing microcapsules. To this end, tensile specimens and flexural specimens containing melamine-urea-formaldehyde (M-U-F) shell walled microcapsules with diameters of 70~130 μm were manufactured. Varying amount of microcapsules in the specimens was considered: 0 wt%, 0.5 wt%, and 1.0 wt%. The tensile and flexural tests were conducted to evaluate mechanical properties of the specimens containing the microcapsules and the thermogravimetric analysis test was performed to evaluate the thermal stability of the specimens containing the microcapsules. The results show that the tensile strength of the specimens was sensitive to the amount of the microcapsules compared to the tensile modulus even though the tensile modulus of the specimens was not significantly affected by the amount of the microcapsules. However, reduction of the tensile strength was not linearly proportional to the amount of microcapsules, similar results were observed in the flexural test. The weight changes of the specimens containing the microcapsules, as a function of temperature, were similar to those specimens without microcapsules. The thermal stability of the specimens was not affected significantly by the microcapsules embedded in the specimens.