Cocure/Precure 경화공정에 의해 제조된 Carbon/Epoxy 복합재료의 미시적 파손거동에 대한 AE 특성

이진경,이준현,이민래,최흥섭,Lee, Jin-Gyeong,Lee, Jun-Hyeon,Lee, Min-Rae,Choe, Heung-Seop 대한기계학회 2000 大韓機械學會論文集A Vol.24 No.10

Mechanical and physical properties of composite materials make a great difference due to their cure process condition. In order to clarify the effect of cure process condition on the microscopic damage behavior and failure mechanism of Carbon/Epoxy composites, three point bend test has been performed. For this purpose, two kinds of specimens with single adhesive and multiple adhesive layers were prepared. For single adhesive layer, four different types of specimen were used, that is, non-sanding, sanding, cocured, laminated specimens. Three different types of specimen were also used for the multiple adhesive layer, non-sanding, sanding, cocured specimens. Acoustic emission technique has also been employed to monitor the damage progresses associated with each micro-failure mechanism. The characteristics of AE parameters associated with micro-failure mechanism of each specimen were discussed.

산화분해촉매를 함유한 rPP/ZnO 나노컴포지트 유연식품포장필름 제조 및 물성 특성 연구

이진경,길보민,이동진,이익모,Lee, Jin-kyoung,Gil, Bo-min,Lee, Dong-jin,Lee, Ik-mo 한국포장학회 2018 한국포장학회지 Vol.24 No.1

본 연구에서는 수출 가능한 식품포장재로 pro-oxidant($d2w^{(R)}$)함유 rPP/ZnO 나노컴포지트 유연필름을 제조하였고, 이 산화분해 필름의 기계적 특성과 항균기능을 조사하였다. 산화분해필름은 일정조건의 열과 자외선 처리를 거친 후 특성분석으로 FT_IR, SEM, UTM, GPC를 측정하여 물성변화를 관찰하였다. 카보닐지수와 하이드록실지수에서 열과 자외선에 노출율이 많아질수록 수치는 상승하였다. 표면분석에서는 rPP/$d2w^{(R)}$/ZnO나노컴포지트 필름의 경우 표면이미지가 매끈하여 ZnO의 첨가가 고분자의 상용성을 향상시켰고, 열과 자외선차단효과로 분해를 감소시키는 효과로 작용하였다. 항균력시험에서는 그람음성균은 대장균으로 그람양성균은 황색포도상구균으로 항균력을 측정하였다. 결과로는, ZnO는 시험에 사용한 농도에서 3로그 이상의 미생물 감소율을 나타내었다. 그러나 유연 필름용으로는 ZnO의 농도가 높아질수록 투명도가 떨어지므로 사용에 제한이 있었다. rPP/$d2w^{(R)}$/ZnO가 함유한 시편에서 인장강도는 40% 상승하였고, 신율은 30% 감소되었다. ZnO를 첨가한 경우 기계적 물성상승과 열 안전성과 자외선차단성을 나타내었다. 산화분해능은 열 노출 $70^{\circ}C$ 온도에서 480시간 경과한 후, 자외선 조사로 72시간 노출 이후 시점의 분자량은 수평균분자량이 1,294 g/mol, 무게평균분자량이 5,920 g/mol로 분해되는 결과를 얻었다. 이것으로 UAE 5009:2009, ASTM 6954의 기준에 준한 필름을 제조할 수 있었다. 비교시편과 본 연구에서 제조한 산화분해필름의 분자량이 80.7%와 75.6% 감소한 결과를 얻음으로서, 자연 산화분해됨을 확인하였다. 식품포장재로서 안전성분석에서는 국내법 중 식품접촉플라스틱 폴리프로필렌의 기준에 적합하였다. In this study, pro-oxidant($d2w^{(R)}$) and rPP/ZnO nanocomposite flexible films for food packaging were prepared, and their mechanical and antimicrobial properties were investigated. As a result, the carbonyl index and hydroxyl index increased with exposured time to heat and UV rays. Surface analysis showed that the addition of zinc oxide improved the dispersibility and compatibility of the polymer, so that the surface of the composite film was smooth and the zinc oxide particles were smaller than the compared film. And it kept the physical properties by heat and UV ray blocking effect, and it worked to reduce decomposition. In the antimicrobial activity test, the microbial reduction rate was 3 logs or more at the use concentration of zinc oxide. The tensile strength was increased and the elongation was decreased. Oxidative degradability of multi-layered film in UV exposured for 72 hours, the molecular weight of the film decreased by 75.6%, 1,294 g/mol Mn and 5,920 g/mol Mw. In the safety analysis of food packaging materials, we obtained that are in standard of polypropylene, a food contact material of domestic law.

TiNi/A16061 형상기억복합재료의 피로균열진전에 대한 냉간압연효과

이진경,박영철,이규창,이상필,조윤호,이준현,Lee Jin-Kyung,Park Young-Chul,Lee Kyu-Chang,Lee Sang-Pill,Cho Youn-Ho,Lee Joon-Hyun 대한기계학회 2005 大韓機械學會論文集A Vol.29 No.10

TiNi alloy fiber was used to recover the original shape of materials using its shape memory effect. The shape memory alloy plays an important role within the metal matrix composite. The shape memory alloy can control the crack propagation in metal matrix composite, and improve the tensile strength of the composite. In this study, TiNi/A16061 shape memory alloy(SMA) composite was fabricated by hot press method, and pressed by a roller for its strength improvement. The four kinds of specimens were fabricated with $0\%,\;3.2\%,\;5.2\%\;and\;7\%$ and volume fraction of TiNi alloy fiber, respectively. A fatigue test has performed to evaluate the crack initiation and propagation for the TiNi/A16061 SMA composite fabricated by かis method. In order to study the shape memory effect of the TiNi alloy fiber, the test has also done under both conditions of the room temperature and high temperature. The relationship between the crack growth rate and the stress intensity factor was clarified for the composite, and the cold rolling effect was also studied.

노화효과를 고려한 저전력 셀프 튜닝 디지털 시스템의 설계

이진경,김경기,Lee, Jin-Kyung,Kim, Kyung Ki 대한임베디드공학회 2018 대한임베디드공학회논문지 Vol.13 No.3

It has become ever harder to design reliable circuits with each nanometer technology node; under normal operation conditions, a transistor device can be affected by various aging effects resulting in performance degradation and eventually design failure. The reliability (aging) effect has traditionally been the area of process engineers. However, in the future, even the smallest of variations can slow down a transistor's switching speed, and an aging device may not perform adequately at a very low voltage. Therefore, circuit designers need to consider these reliability effects in the early stages of design to make sure there are enough margins for circuits to function correctly over their entire lifetime. However, such an approach excessively increases the size and power dissipation of a system. As the impact of reliability, new techniques in designing aging-resilient circuits are necessary to reduce the impact of the aging stresses on performance, power, and yield or to predict the failure of a system. Therefore, in this paper, a novel low power on-chip self-tuning circuit considering the aging effects has been proposed.

고등학교 교과서 읽기 자료의 문제점과 개선 방안: 의사소통적 관점에서

이진경,Lee, Jin-Kyong 한국영어어문교육학회 2009 영어어문교육 Vol.15 No.4

This study aims to examine the reading materials of high school English textbooks to propose the integration of the literary texts into reading materials in the classroom for development of communicative competence. Five kinds of high school English textbooks were critically examined in terms of three factors -limited text types, deficit of emotional adjectives and non-authenticity- selected by the author as characteristics of non-communicative language teaching materials. With regard to text types, more than half of the reading materials were expository and simple narratives. This imbalance of text types led materials to the deficit of emotional vocabulary. These factors seem to be closely related to the issue of authenticity of reading materials. Compared to the authentic texts, fabricated texts are likely to make reading vapid and boring task. On the basis of these results, some pedagogical suggestions are made.

M.엘리아데의 종교현상학 관점으로 본 현대 기독교공간의 특성에 관한 연구

이진경,김문덕,Lee, Jin-Kyung,Kim, Moon-Duck 한국실내디자인학회 2017 한국실내디자인학회논문집 Vol.26 No.4

Modern Christian spaces are developing from the past architectural styles to the phenomenological aspects. This study was conducted since it was judged that research and analysis is desirable with the application of religious phenomenological theories which fit the characteristics of religious spaces. A scholar of religion, M. Eliade studied religious phenomenology based on religious studies. This study analyzed the characteristics of religious phenomenology of the Christian spaces based on his theory. As a research method, this study analyzed the category of religious studies and religious phenomenology derived from them and selected M. Eliade as one of the theorists in the field of religious phenomenology. Study drew out the characteristics of Christian spaces from the perspective of M. Eliade's religious phenomenology as follows; In the Christian spaces, characteristics of experiential spatiality and ambiguous spatiality appeared in relation to the spaces of 'Sacred' and 'Profane' which M. Eliade aimed to explain. The characteristics of Christian spaces drawn out from the time of 'Sacred' and 'Profane', which is M. Eliade's theory, were fundamental temporality, environmental temporality and subjective temporality. From the structure and form of 'Sacred' and 'Profane', which is M. Eliade's theory, the characteristics of Christian spaces can be considered to be formative symbolism and physical naturalness. Various characteristics of Christian spaces materialize the concepts of 'hierophany' and 'sublimity' vaguely felt in religious spaces. The results of this study is expected to provide researchers, religious people and general public who study Christian spaces with research basis to further objectify results of their studies as well as basic data on the phenomenological methodology of religion.

건축기행 - 사람과 예술, 건축과 자연이 빚어낸 아트사이트 나오시마

이진경,Lee, Jin-Gyeong 대한건축사협회 2013 建築士 Vol.2013 No.1

Betty Neuman의 SysteM model적용 간호중재 사례

이진경,Lee, Jin-Gyeong 대한간호협회 1995 대한간호 Vol.33 No.5

스테인레스 316L강의 배관용접결함에 대한 유도초음파 특성 평가

이진경,이준현,Lee, Jin-Kyung,Lee, Joon-Hyun 한국비파괴검사학회 2015 한국비파괴검사학회지 Vol.15 No.1

스테인레스강은 고온, 고압에서 부식에 효과적인 재료로써 액화수소, 가스 등을 저장하는 저장용기 및 고온의 유체들을 이송하는 배관재료로 널리 사용되고 있다. 일반적으로 스테인레스강의 용접은 TIG용접이 이용되어지고 있으며 용접후 용접부위에 발생하는 초기 용접결함 및 사용중 발생하는 열적 피로균열 등이 재료의 신뢰성을 저하하는 요인들로 지적되고 있다. 본 논문에서는 레이저 유도초음파를 이용하여 초기 용접결함에 대한 초음파 특성 규명을 위하여 스테인레스강의 용접부에 인공균열의 크기를 5 mm, 10 mm, 20 mm 길이로 가공후 유도초음파의 결함 길이 변화에 따른 특성을 평가하였다. 배관의 두께 등을 고려하여 L(0,1)모드와 L(0,2)모드를 이용하였으며 각각의 모드가 결함의 길이 변화에 따라 변화를 보였지만 L(0,2)모드가 L(0,1)모드보다 결함 길이에 더욱 민감하게 반응하였다. 본 연구에서는 L(0,1)모드와 L(0,2)모드의 진폭비를 구하여 결함과의 연관성을 평가한 결과 결함 길이와 선형적인 관계를 나타냄으로써 각 모드를 단독적으로 평가하는 것보다는 두 모드의 진폭비를 이용하여 결함을 평가하는 것이 더욱 효과적임을 알 수 있었다. Stainless steel is a popular structural materials for liquid-hydrogen storage containers and piping components for transporting high-temperature fluids because of its superior material properties such as high strength and high corrosion resistance at elevated temperatures. In general, tungsten inert gas (TIG) arc welding is used for bonding stainless steel. However, it is often reported that the thermal fatigue cracks or initial defects in stainless steel after welding decreases the reliability of the material. The objective of this paper is to clarify the characteristics of ultrasonic guided wave propagation in relation to a change in the initial crack length in the welding zone of stainless steel. For this purpose, three specimens with different artificial defects of 5 mm, 10 mm, and 20 mm in stainless steel welds were prepared. By considering the thickness of s stainless steel pipe, special attention was given to both the L(0,1) mode and L(0,2) mode in this study. It was clearly found that the L(0,2) mode was more sensitive to defects than the L(0,1) mode. Based on the results of the L(0,1) and L(0,2) mode analyses, the magnitude ratio of the two modes was more effective than studying each mode when evaluating defects near the welded zone of stainless steel because of its linear relationship with the length of the artificial defect.

Al 7075/CFRP 샌드위치 복합재료의 강도 및 손상특성에 대한 비파괴 평가

이진경,윤한기,이준현,Lee, Jin-Kyung,Yoon, Han-Ki,Lee, Joon-Hyun 대한기계학회 2002 大韓機械學會論文集A Vol.26 No.11

A hybrid composite material has many potential usage due to the high specific strength and the resistance to fatigue, when compared to other composite materials such as fiber reinforced plastic(FRP) and metal matrix composite(MMC). However, the fracture mechanism of hybrid composite material is extremely complicated because of the bonding structure of metals and FRP. In this study, Al 7075 sheets and carbon epoxy preprags were used to fabricate the hybrid composite. Recently, nondestructive technique has been used to evaluate the fracture mechanism of these composite materials. AE technique was used to clarify the microscopic damage behavior and failure mechanism of A17075/CFRP hybrid composite. It was found that AE paralneters such as AE event, energy and amplitude were effective to evaluate the failure process of Al 7075/CFRP composite. In addition, the relationship between the AE signal and the characteristics of fracture surface using optical microscope was discussed.