• Proceedings of the Korean Institute of Industrial Safety Conference
• /
• 1998.05a
• /
• pp.45-50
• /
• 1998

최근 항공기, 자동차 및 각종 플랜트 설비의 고온용 경량 내열성 소재로서 구조용 세라믹스 재료가 큰 주목을 받고 있다. 그러나, 이러한 구조용 세라믹스 재료도 어느 이상의 고온에서는 크지 않은 응력하에서도 크립에 의한 영구 변형이 일어나서 강도 저하 및 치수 변화로 이어지며, 이로 말미암아 정밀 부품으로서의 기능을 상실할 뿐 아니라 심한 경우에는 파손에까지 이를 수 있다. (중략)

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.34 no.1
• /
• pp.65-73
• /
• 2006

The high temperature occurs due to the combustion gas from engine in unmanned aerial vehicles (UAV). The high temperature may cause serious damages in UAV structure. The Functionally Graded Material (FGM) is chosen as a candidate material of the engine duct structure. A functionally graded material (FGM) is a two- component mixture composed by compositional gradient materials from one material to the other. In contrast, traditional composite materials are homogeneous mixtures, and involve compositions between the desirable properties of the component materials. Since significant proportions of an FGM contain the pure form of each material, the need for compromise is eliminated. The properties of both components can be fully utilized. Thermal stress analysis of FGM layers (20, 40, 60, 80 and 100) is performed in this paper. In addition, the creep behavior of FGM applied in duct structure of an engine is analyzed for better understanding of FGM characteristics.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.27 no.3
• /
• pp.199-206
• /
• 2014

In this paper, a scheme to evaluate the response variability for functionally graded material (FGM) beam with varying sectional area is presented. The randomness is assumed to appear in a spatial domain along the beam axis in the elastic modulus. The functionally graded material categorized as composite materials, however without the drawbacks of delamination and occurrence of cracks due to abrupt change in material properties between layers in the conventional composite materials. The functionally graded material is produced by the gradual solidification through thickness direction, which endows continuous variation of material properties, which makes this material performs in a smooth way. However, due to difficulties in tailoring the gradients, to have uncertainty in material properties is unavoidable. The elastic modulus at the center section is assumed to be random in the spatial domain along the beam axis. Introducing random variables, defined in terms of stochastic integration, the first and second moments of responses are evaluated. The proposed scheme is verified by using the Monte Carlo simulation based on the random samples generated employing the spectral representation scheme. The response variability as a function of correlation distance, the effects of material and geometrical parameters on the response variability are investigated in detail. The efficiency of the proposed scheme is also addressed by comparing the analysis time of the proposed scheme and MCS.

• Food Industry And Nutrition
• /
• v.5 no.3
• /
• pp.52-56
• /
• 2000

우리 민족 전래의 발효식품인 김치는 많은 생리활성물질들이 존재하는 다양한 재료를 사용하여 만들어지며 여러 효소와 미생물들이 관여하는 복잡한 발효과정을 거치면서 또다른 생리활성물질들을 생성한다. 이들 물질은 복합적으로 작용하여 항산화활성을 나타내며 실험방법들에 따라 조금씩 다른 양상을 보이지만 김치 재료물질들의 종류 및 함량, 발효정도 등은 김치의 항산화성에 중요한 영향을 미치는 인자들이라고 할 수 있다. 본 총설은 김치의 항산화성을 in vitro 및 in vivo수준에서의 연구결과들을 중심으로 살펴보았다.

• Proceedings of the Korean Society of Food Science and Nutrition Conference
• /
• 2000.11a
• /
• pp.107-114
• /
• 2000

우리 민족 전래의 발효식품인 김치는 많은 생리활성물질들이 존재하는 다양한 재료를 사용하여 만들어지며 여러 효소와 미생물들이 관여하는 복잡한 발효과정을 거치면서 또다른 생리활성물질들을 생성한다. 이들 물질은 복합적으로 작용하여 항산화활성을 나타내며 실험 방법들에 따라 조금씩 다른 양상을 보이지만 김치 재료물질들의 종류 및 함량, 발효정도 등은 김치의 항산화성에 중요한 영향을 미치는 인자들이라고 추측할 수 있다. 본 총설은 김치의 항산화성을 in vivo 및 in vivo수준에서의 연구결과들을 중심으로 살펴보았다.

• Composites Research
• /
• v.26 no.5
• /
• pp.315-321
• /
• 2013

In this work, pitch-carbonized glass fibers were prepared for reinforcement of composites. The influence of acid functionalization of the fibers on the morphological, mechanical, and thermal properties of fiber-reinforced epoxy matrix composites was investigated. The acid functionalization of the fibers led to 10 and 150% increases in the mechanical and thermal properties, respectively, as compared to carbon fiber-reinforced composites. This can be attributed to the superior orientation of fiber structures and good interfacial interactions between fillers and epoxy matrix, resulting in enhanced degree of dispersion and formation of thermally conductive paths in the functionalized composites.

• Proceedings of the Korean Fiber Society Conference
• /
• 2003.10b
• /
• pp.285-286
• /
• 2003

폴리우레탄은 복합재료의 함침 및 코팅용으로 가장 보편적으로 사용되는 수지이다. 폴리우레탄-부직포 복합소재는 폴리에스테르 또는 나일론과 같은 합성섬유로 제조된 부직포에 폴리우레탄으로 함침한 후 다시 폴리우레탄으로 코팅함으로써 소재의 단위 무게 당 폴리우레탄이 차지하는 비율이 매우 높고, 최종제품의 물성에 많은 영향을 끼치므로 이와 관련한 연구는 주로 기능성 및 내구성을 부여하는데 맞춰지고 있다[1]. (중략)

• Proceedings of the KAIS Fall Conference
• /
• 2008.11a
• /
• pp.427-429
• /
• 2008

본 연구에서는 CNT표면에 공유결합으로 기능성기를 도입하는 화학적 방법을 사용하여 PP/MWNT 복합재를 제조하였으며, 기능성기가 도입된 CNT를 용액-용융 블랜딩 방법을 이용하여 탄소나노튜브를 분산시켰다. 탄소나노튜브 표면에 기능성기를 도입한 경우가 상대적으로 분산도가 양호하였다.

• Composites Research
• /
• v.30 no.1
• /
• pp.1-6
• /
• 2017

Epoxy resin (EP) is one of the most famous thermoset materials. In general, because EP has three-dimensional random network, it possesses thermal properties like a typical heat insulator. Recently, there has been increasing interest in controlling the network structure for making new functionality from EP. Indeed, the new modified EP represented as liquid crystalline epoxy (LCE) is spotlighted as an enabling technology for producing novel functionalities, which cannot be obtained from the conventional EPs, by replacing the random network structure to oriented one. In this paper, we review current progress in the field of LCEs and their application for the highly thermal conductive composite materials.

• Composites Research
• /
• v.31 no.4
• /
• pp.128-132
• /
• 2018

Multi-material design with metals and composites can keep structural functions as well as reduce the weight of automotive parts. However, recycling of automotive parts should be considered due to the increasing emphasis on the environments and pollutions. We derived the key issues for increasing the recycling rate of automotive parts by carrying out a survey targeting representatives and workers related with automotive recycling. The core of the key issues was the separation technology of adhesively bonded metal-composite hybrid structures, so we conducted the basic research and suggested the separation technology which can easily be adopted into the recycling industries.