• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.6
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• pp.78-84
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• 2017

Consistent efforts have been made to reduce the weight of automotive parts by using lightweight materials. This has resulted in the replacement of conventional steels in car body structures with high-strength steels, and the current usage rate has reached 50%. This study examines the structural stiffness and energy absorption capability of bumper beams made of high-strength steels. New types of bumper beam cross sections are proposed.The structural stiffness and maximum bending force were computed via finite element analysis as about 25tons and 7.5tons/mm, and there were no significant differences among the proposedcross sections. Dynamic analysis was also carried out to investigate the energy absorption capabilities of the bumper beams, and the effects of materials and thickness reduction were analyzed. High-strength steel can be used to achieve weight reduction with comparable structural performance to conventional bumper beams.

• Elastomers and Composites
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• v.46 no.2
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• pp.118-124
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• 2011

Recently, the need of new materials which have excellent physical properties and functional characteristics has been increased in all industries. In particular, body weight reduction via new materials in aerospace industry was significantly emphasized by the requirement of environmental protection through the fuel savings and reduction of greenhouse gas, i.e., carbon dioxide($CO_2$). Also, for various applications, the development of high performance custom materials with excellent physical properties was the current primary goal of materials science and technology. In this respect, carbon fiber-reinforced composites were the most candidates among the various materials. Indeed, carbon fiber-reinforced composites have been lately used as essential materials for the weight reduction of aircraft and the demand has increased remarkably. Therefore, in this paper, we focused on the need of carbon fiber composites in the fields of aircraft and technique status.

• Journal of the Korean Society of Radiology
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• v.15 no.2
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• pp.191-199
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• 2021

The purpose of this research is to analyze the radiation shielding effect of soft magnetic material to confirm the applicability to the military facilities. The soft magnetic material is known to be effective in shielding EMP. If this material is also effective in radiation shielding, it is expected that it has a lot of applicability in military protection. In particular, this material contains boron, so it will be effective in shielding neutrons. In this research, experiments were conducted using Cs-137 and Co-60 sources to check the gamma ray shielding effect. In addition, the Monte Carlo N-Particle(MCNP) modeling was applied to evaluate the gamma ray and neutron shielding effect of a military command tent. As a result, as the soft magnetic thickness increased, the shielding performance improved according the linear attenuation law of gamma ray and neutron. Therefore, this research verified that the application of soft magnetic material for military purposes in radiation shielding would be effective.

• Journal of Energy Engineering
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• v.28 no.1
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• pp.10-16
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• 2019

The purposes of this study is to secure subsidence stability and economical efficiency of lightweight foamed concrete. The composition of lightweight foamed concrete was designed for OPC by substituting with constant contents of calcium sulfaluminate and fly ash. It is found that the flow of lightweight foamed concrete decreased with early ettringite formation by CSA. The initial strength increased with the decrease of drying time of lightweight foamed concrete when CSA was substitution to 10%. The settlement deep of foamed concrete improved the settlement stability by replacing CSA, which prevented shortening of the coagulation time and bubble puffing.

• Proceedings of the Korean Society of Dyers and Finishers Conference
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• 2011.03a
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• pp.93-93
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• 2011

스포츠웨어 바람막이용도에 사용되는 대부분의 소재는 폴리아미드계 소재이며, 국내에서는 대부분 나일론6 소재를 사용하고 있다. 최근 소비자들의 요구는 점점 경량화되고 있고 야외활동 증가와 더불어 착용감이 우수한 소재를 요구하고 있다. 이러한 시즘에 국내에서 많이 사용되는 나일론6 소재를 이용하여 직물단계에서 경량감과 스트레치성이 발현될수 있는 나일론6 경량 Mechanical 스트레치 직물 개발에 대한 연구를 진행하고자 함이다. 본 연구에서는 직물단계에서 경량감과 스트레치성이 발현될수 있는 나일론6 경량 Mechanical 직물개발을 위해 공중합 나일론6 폴리머와 일반 나일론6 폴리머를 복합방사설비를 이용하여 SIDE BY SIDE POY 26d/6f 원사를 제조한 후, Nip Belt 가연설비로 연신비, 가연 1st 히터온도, 벨트각도 조건에 따라서 제조된 4가지의 나일론6 가연사 DTY 20d/6f와 T사에서 생산되고 있는 나일론6 가연사 DTY 20d/7f를 동일한 직물설계 조건에서 위사방향으로 제직을 실시하였다. 직물설계 조건은 경사를 나일론 DTY 20d/7f, 경사밀도는 2가지, 위사밀도 2가지으로 설계하여 제직하였으며, 이렇게 제조된 직물(생지)를 일반 나일론6 염색가공 공정조건으로 전처리, 염색, 가공, 코팅 공정을 거친후, 신축성 평가를 실시하였다. 동일한 제직조건 및 염색가공 조건에서 제조된 직물의 신축성은 가연조건인 가연 연신비가 높고, 가연 1st 히터온도가 높은 조건에서 높게 나타남을 알 수 있었다. 경사밀도가 낮은 조건이 수축이 많이 진행됨을 알 수 있었으며, 가연조건인 가연 연신비가 높고, 가연 1st 히터온도가 높은 조건에서 수축이 더 많이 이루어짐을 알 수 있었다. 권축률이 높은 가연사 조건이 그만큼 수축이 많이 들어옴을 나타내는 결과로 사료되며, 위사밀도가 낮은 조건이 수축이 좀 더 많이 진행됨을 알 수 있었으며, 위사밀도가 너무 많으면 가연사끼리 상호 수축할 수 있는 정도를 감소시키는 결과로 판단된다. 전처리, 염색가공, 코팅이 완료된 최종 원단의 신축성 평가를 실시한 결과, 비교사로 제직된 최종 원단은 8~10%수준, 가연사 제조조건에 따른 제조된 4가지의 가연사의 신축성은 12~18%의 신축성을 보임을 알수 있었다. 향후, 제직설계 및 염색가공 조건의 다양화로 연구를 진행할 계획이다.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.37 no.9
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• pp.1099-1107
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• 2013

This study proposes a weight reduction design for urban transit, specifically, a Korean EMU carbody made of aluminum extrusion profiles, according to size optimization and useful material changes. First, the thickness of the under-frame, side-panels, and end-panels were optimized by the size optimization process, and then, the weight of the Korean EMU carbody could be reduced to approximately 14.8%. Second, the under-frame of the optimized carbody was substituted with a frame-type structure made of SMA 570, and then, the weight of the hybrid-type carbody was 3.8% lighter than that of the initial K-EMU. Finally, the under-frame and the roof-panel were substituted with a composite material sandwich to obtain an ultralight hybrid-type carbody. The weight of the ultralight hybrid-type carbody was 30% lighter than that of the initial K-EMU. All the resulting carbody models satisfied the design regulations of the domestic Performance Test Standard for Electrical Multiple Unit.

• Journal of Institute of Convergence Technology
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• v.4 no.1
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• pp.29-32
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• 2014

최근 유가상승 및 환경오염으로 인하여 자동차 연비 개선에 대한 관심이 날로 증가하고 있어 자동차 제조사들은 다양한 접근방법을 통해 경량화를 달성하고자 하고 있다. 경량화 방법으로는 경량재료의 적용, 고강도 소재를 이용한 부품소형화, 조립식 파트의 일체형 모듈화 등이 있으며, 본 연구에서는 경량구조재료인 마그네슘 합금을 자동차용 스크롤 압축기에 적용하기 위하여 기존 알루미늄 합금부품과의 열팽창 및 열변형의 비교를 통해 마그네슘 합금 적용한 스크롤 부품의 설계시 고려되어야 할 요소들을 분석 및 제시하고자 한다.

• Elastomers and Composites
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• v.47 no.1
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• pp.65-74
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• 2012

Recently, the need of developing eco-friendly materials has been required with restriction strengthening on environment and energy saving by the resource depletion worldwide. These trends are not an exception in transport industry including automobile. In addition, these materials have to fulfill not only the high quality and cheap price but also the high-performance which meet the needs of costumer and society. Among the various materials, carbon fiber-reinforced composite which is actively studying for lightweight of the automobile is one of the most suitable candidates. Indeed, the carbon fiber-reinforced composites are used as the essential materials to substitute body and other parts in automobile and the demand is increasing largely. Carbon fiber-applied automobile has improved brake, steering, durability and high fuel efficiency, leading to the energy conservation and minimizing carbon dioxide emissions. This paper focuses on the necessity of carbon fiber-reinforced composites for lightweight of automobile and its technical trends.

• Proceedings of the Korean Ceranic Society Conference
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• 2004.04b
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• pp.39.3-39.3
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• 2004

• Fiber Technology and Industry
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• v.14 no.1
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• pp.18-26
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• 2010