철도차량 차체용 탄소섬유/에폭시 복합재의 환경노화 특성 평가

오진오(Oh Jin-Oh),윤성호(Yoon Sung-Ho),김정석(Kim Jung-Suk),한성호(Han Seong Ho) 한국철도학회 2007 한국철도학회 학술발표대회논문집 Vol.- No.-

Mechanical and thermal analysis properties of carbon fiber/epoxy composite for train carbody were evaluated by varying with environmental factors such as ultraviolet, temperature, and moisture. Accelerated environmental aging tester was utilized for this study. Testing temperature was set to 80℃ and ultraviolet was obtained through xenon-arc lamp. To consider moisture, water sprayed on specimen for 18 minutes every 2 hour. All the specimens were made of CF1263/Epoxy composite. Mechanical properties such as tensile, bending, and shear properties were evaluated through a material testing system. Also, thermal analysis properties such as storage shear modulus, loss shear modulus, and tan δ were measured through dynamic mechanical analyzer. Finally surfaces of the composite exposed to environmental factors were examined using a scanning electron microscope. From experimental results, those properties of CF1263/Epoxy composite were shown to be slightly decreased due to environmental factors.

GRP 복합관의 열팽창계수 측정

오진오 ( Jin Oh Oh ),윤성호 ( Sung Ho Yoon ) 한국복합재료학회 2012 Composites research Vol.25 No.1

본 연구에서는 스트레인게이지 회로를 이용하여 GRP 복합관의 열팽창계수를 측정하고자 하였다. 이를 위해 다양한 스트레인게이지 회로를 적용하여 알루미늄 보의 열팽창계수를 측정함으로써 측정방법의 타당성을 검증하였다. 또한 스트레인게이지의 부착위치와 반복횟수를 달리하며 또한 열팽창계수가 다른 스트레인게이지를 적용한 경우에 대해 GRP 복합관의 길이방향 및 원주방향 열팽창계수를 측정함으로써 열변형률 결과와 측정결과의 재현성에 미치는 영향을 조사하였다. 연구결과에 따르면 GRP 복합관의 경우 보강된 유리섬유에 의해 원주방향의 열변형률이 제한되어 원주방향 열팽창계수가 길이방향의 열팽창계수에 비해 낮게 나타났다. 또한 GRP 복합관의 후경화로 인해 측정횟수가 증가할수록 측정된 열팽창계수는 다소 증가하지만 증가폭은 점차 감소하였다. 아울러 열팽창계수가 다른 스트레인게이지를 적용하더라도 기준보상시편을 통해 스트레인게이지의 열변형률을 보상하면 동일한 열팽창계수가 얻어짐을 알 수 있었다. This study was focused on the measurement of thermal expansion coefficients for GRP pipe through strain gage circuits. First of all, thermal expansion coefficients of aluminum beam were measured to examine the validity of the suggested method by using various types of strain gage circuits. Thermal expansion coefficients of GRP pipes along axial and hoop directions were measured to investigate the effect of the location of strain gages, number of repeated measurements, and strain gage types with different thermal expansion coefficients on the thermal strains and the repeatability of measured results. According to the results, thermal expansion coefficients of GRP pipes along hoop direction were lower than those along axial direction due to the constraint effect of reinforced glass fibers on thermal strains along hoop direction. As measurements were repeated, thermal expansion coefficients of GRP pipes were slightly increased, but the degree of increase became smaller. Finally, the same thermal expansion coefficients were obtained irrespective of different types of strain gages with different thermal expansion coefficients if thermal strains of strain gages were compensated by using reference compensation specimen.

치료효율 극대화를 위한 자가치료제의 열적/기계적 특성 연구

허광수(Kwang Su Heo),오진오(Oh Jin Oh),윤성호(Sung Ho Yoon) 한국정밀공학회 2004 한국정밀공학회 학술발표대회 논문집 Vol.2004 No.10월

Recently, the self-healing technique is being investigated to repair the damaged polymeric composites by the use of microcapsules with the healing agent. This technique can obtains both the damage detection and the damage repair simultaneously over the conventional repairing techniques. In this study, the effects of the catalyst ratio to the healing agent and thermal characteristics to the mixtures of healing agent are investigated through single lap shear tests and DSC. The Healing agents such as DCPD, ENS, and their mixtures are considered and Grubbs" catalyst is used as a catalyst.

탄소섬유/에폭시 복합재 링 시편의 노화 특성 평가

윤성호 ( Sung Ho Yoon ),오진오 ( Jin Oh Oh ) 韓國複合材料學會 2009 Composites research Vol.22 No.6

입학전형별 대학생 핵심역량 및 전공역량의 차이 분석 : D대학교 사례 분석을 중심으로

최정희 ( Choi¸ Jung-hui ),오진오 ( Oh¸ Jin-oh ) 인하대학교 교육연구소 2020 교육문화연구 Vol.26 No.6

본 연구는 입학전형의 차이가 대학생의 핵심역량 및 전공역량에 미친 영향을 파악하는 것을 목적으로 한다. 수도권 소재 D대학교를 사례로 선정하였고, D대학교에서 개발한 진단 척도를 사용하여 역량을 측정하였다. 입학전형에 따른 역량의 차이를 살펴보기 위해 각 역량을 종속변수로 설정하여 독립표본 t검증을, 성별과 학년 내에서 입학전형에 따른 역량 평균의 차이를 살펴보기 위해 내재된 이원분산분석(nested two-way ANOVA)을 실시하였다. 분석 결과, 핵심역량의 경우 전체적으로 정시전형과 학생부종합전형 입학생의 평균 역량이 높은 편이고, 수시전형 입학생의 역량 평균이 낮은 것으로 나타났다. 전공역량의 경우 대체적으로 정시전형 입학생들의 평균이 높은 편이고, 수시전형 입학생들의 평균이 낮게 나타났다. 연구 결과를 통해 얻을 수 있는 몇 가지 시사점이 있다. 우선 수시전형 입학생들의 역량 점수가 높지 않다는 결과를 고려한다면 앞으로 신입생 선발 전형에서 잠재적 핵심역량을 확인할 수 있는 절차나 평가지표의 개발이 필요할 것이다. 전공역량에 있어서도 전반적으로 정시전형이나 학생부종합전형으로 입학한 학생들의 역량점수가 수시전형으로 입학한 학생들보다 높게 나타났다는 것은 고려한다면 수시전형 입학생들의 전공역량 강화를 위한 별도의 프로그램 개발 등이 필요한 것으로 보인다. 수시전형 입학생에게 전공 특화된 비교과 프로그램의 개발 등을 고려할 수도 있을 것이다. 전체적으로 수시전형의 축소 혹은 수시전형에서 역량 중심의 평가가 이루어질 수 있도록 전형 형식이나 내용의 개선이 필요하다. The purpose of this study is to find a desirable direction for admission policy by analyzing differences in core competency and major competency of college students by admissions type. Differences in competency were analyzed according to the three main admission types: Early admission based on the comprehensive school records, Early admission based on school grades, and Regular admission based on SAT scores. D University, located in the metropolitan area, was selected as an example, and the competency was measured using the survey scale developed by D University. As a result of analysis, in the case of the six core competencies, there was a meaningful difference according to the admission type in all competency. Overall, the average competency of students admitted through Regular and Early admission based on school records was high, and the competency of students admitted through Early admission based on comprehensive records was low. Research result shows that in 7 out of 10 major competencies- self-directed, knowledge utilization, logical thinking, creative problem-solving, challenge, knowledge convergence, and global citizenshipthere was a significant difference according to the admission type. In general, the average of the students admitted through the Regular admission process based on SAT scores is high and the average of the students through Early admission process is low. The results of this study are useful for reference in determining the ratio between regular and early admission at university. More effort to confirm potential competency of the admission applicants and to develop educational programs to strengthen students’ competency is required.

탄소섬유직물/에폭시 복합재의 혼합모우드 층간파괴 거동

윤성호(Sung-Ho Yoon),허광수(Kwang-Soo Heo),오진오(Jin-Oh Oh) 한국항공우주학회 2007 韓國航空宇宙學會誌 Vol.35 No.1

MMF 시험을 적용하여 혼합모우드 비율을 20%~90%의 범위 내에서 변화시키면서 탄소섬유직물/에폭시 복합재의 혼합모우드 층간파괴 거동을 조사하였다. 혼합모우드 층간파괴 거동을 예측하기 위해 NL점과 5% offset점에 근거한 혼합모우드 층간파괴 결정식을 제시하였다. 파단면 양상과 균열진전 거동은 이동식 현미경과 전자현미경을 통해 조사하였다. 연구결과에 따르면 혼합모우드 층간파괴 거동은 NL점에 근거한 경우 매개변수 m=1.5와 n=0.5, 5% offset점에 근거한 경우 매개변수 m=2와 n=3인 혼합모우드 충간파괴 결정식에 의해 잘 예측되어진다. 파단면 양상과 균열진전 거동은 혼합모우드 비율에 매우 민감하게 변하며 MMF 시험은 혼합모우드 층간파괴인성의 평가에 성공적으로 적용됨을 알 수 있었다. Mixed mode interlaminar fracture behaviors of carbon fabric/epoxy composites were investigated through MMF (Mixed Mode Flexural) test by varying mixed mode ratio ranging from 20% to 90%. Mixed mode interlaminar fracture criteria based on NL point and 5% offset point were also suggested in order to predict mixed mode interlaminar fracture behaviors. Fracture surfaces and crack propagating behaviors were examined through a travelling scope and a scanning electron microscope. According to the results, mixed mode interlaminar fracture behaviors can be predicted by mixed mode interiaminar fracture criterion with m=1.5 and n=0.5 on the basis of NL point or mixed mode interlaminar fracture criterion with m=2 and n=3 on the basis of 5% offset point. Fracture surfaces and crack propagating behaviors are sensitive to mixed mode ratios. MMF test can be successfully applicable in evaluating mixed mode interiaminar fracture toughness of carbon fabric/epoxy composites.

틸팅차량 차체용 복합재 구조재에 대한 모우드 Ⅱ 변형 하의 손상허용 평가 기법 연구

윤성호(Yoon Sung Ho),허광수(Heo Kwang Su),오진오(Oh Jin Oh),이상진(Lee Sang Jin),김정석(Kim Jung Suk) 한국철도학회 2006 한국철도학회 학술발표대회논문집 Vol.- No.-

Damage tolerance under Mode Ⅱ deformation of carbon fabric/epoxy composite, which was applicable to a tilting train carbody, was investigated by a Mode Ⅱ interlaminar fracture test. The specimens were made of plain woven fabric with epoxy and a delamination at one end was made by inserting Teflon film with the thickness of 12.5㎛ or 25.0㎛. The equation for mode Ⅱ interlaminar fracture toughness was suggested based on the effective crack length from the compliance of load-displacement curve. Mode II interlaminar fracture behaviors were investigated through an optical travelling scope and a scanning electron microscope.