• Magazine of the Korea Concrete Institute
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• v.13 no.5
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• pp.77-81
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• 2001

부식 열화는 교량 기술자들에게 있어서 지속적인 도전을 요구하는 문제가 되어왔는데, 스텔스 항공기를 개발하게 한 새로운 재료 기술은 교량의 부식을 해결할 수 있게 하였다. 즉, 경량의 고강도 재료로 높은 피로 저항성을 갖고 있고, 부식에 강한 복합체는 교량의 재료로서 아주 바람직한 성질을 갖고 있다 섬유 보강 폴리머(FRP) 복합재료를 교량의 건설에 이용하려는 프로젝트는 1998년 현재 80 여 개가 넘게 진행되고 있는데, 이 중 미국 내에서 31개의 프로젝트가 수행되고 있다. 이 글은 미국 내에서 FRP복합체를 교량 공학 분야에 적용하려는 초기의 성공적인 시도들에 관한 내용으로 복합체의 장점, 특성, 교량 적용시 고려 사항, 그리고 향후 복합재료에 관한 기술을 토목 구조물에 적용하는데 필요한 소요 기술 등에 관하여 정리한 것이다. 이 새로운 재료는 신설 구조물의 건설과 기존 교량의 보수 및 보강에 모두 적용할 수 있으며, FRP복합체 기술을 토목 구조물과 기반 시설물 건설 분야에 적용하는 것은 지금까지 성공적인 결과를 보여 주고 있다 미국연방도로국(FHWA, Federal Highway Administration)은 이 기술을 미국 내 교통 기반 시설물인 신규 교량의 건설은 물론 기즌 교량의 보수 및 보강에 활용하는 방안에 대하여 관심을 갖고 있다.

• Aerospace Engineering and Technology
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• v.2 no.1
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• pp.213-222
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• 2003

Some analytical methods to analyze low-velocity impact force history of composite laminated structures used in aerospace vehicles are reviewed. A classical method used at initial research of low-velocity impact problem in 1980s was reviewed on its physical meaning, and the approximate method assuming the shape of impact force history as a sinusoidal wave was reviewed. A parametric study on contact constant and exponent in contact law was performed in order to analyze an effect on impact force history, and finally its was understood that impact force history could be analyzed accurately even though the linearized contact law was used. Also, in this paper it was shown that impact problem could be analyzed simply and easily using a commercial finite element code.

• Composites Research
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• v.23 no.1
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• pp.31-36
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• 2010

The improvement of electrical conductivity of carbon-fiber reinforced plastics (CFRP) has been investigated by silver nano-particles coating for the purpose of lightning strike protection. Silver nano-particles in colloid were sprayed on the surface of carbon fibers, which were then impregnated by epoxy resin to form a CFRP specimen. Electrical resistance was measured by contact resistance meter which utilize the principles of the AC 4-terminal method. Electrical resistance value was then converted to electrical conductivity. The coated silver nano-particles on the carbon fibers were verified by SEM and EDS. The electrical conductivity was increased by three times of the ordinary CFRP.

• Composites Research
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• v.12 no.1
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• pp.19-27
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• 1999

A design development test for carbon/epoxy composite laminates for an aircraft flight control system is performed. The design development test includes moisture absorbing test, tensile, compressive, bearing and lap shear tests. The moisture absorbing behavior for different fiber orientation angles is investigated and the changes in mechanical characteristics are compared. In the in-plane tensile test, the effect of damages such as scratches and impacts is studied. The bearing test is performed for different fastening types. The resulting design allowable stress and environmental load enhancement factor are used for the structural analysis and certification tests for the flight control system.

• Journal of Advanced Navigation Technology
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• v.15 no.6
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• pp.977-985
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• 2011

Airborne separation assurance is a key requirement for Free Flight Airspace operations, This paper study the feasibility of airborne separation assurance for free flight Airspaces operations by evaluating the efficiency measurement models. Three qualitatively different methods are utilized; one based Ground and Air conflict probability model, other based Dynamic Density model. the other based Direct operating cost model. The evaluation is Direct Operating Cost model and Two metrics are utilized for the efficiency measurements; airborne separation assurance performed quite well in the Free Flight evaluation; (1) 2 scenario of the conflict situations are resolved; (2) The MD-80 flight peformed separation assurance and efficiency, Not only appling for geometric method algorithm is more efficiently than potential method, but also the most efficiently geometric combined method.

• Korean Journal of Materials Research
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• v.5 no.1
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• pp.75-86
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• 1995

In order to manufacture and produce the components to be used for developing aerospace products, it is essential to determine the conformity of material characteristics to the design requirements. However, since the Korean industry has no experience to develop aircraft and spacecraft, the national certification system has not been established. Hence, it is necessary to define the qualification methodology of material to establish the durability and the safety of aircraft and spacecraft. In this paper the characterization methodology which has been performed in aeronautically advanced countries for determination of conformity in materials and production process is reviewed. The change of material properties due to the space environment and the example of evaluation program of composites for the application of aircraft are presented. so that the foundation of evaluation system for aerospace materials can be initiated.

• Aerospace Engineering and Technology
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• v.12 no.2
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• pp.193-201
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• 2013

Propeller is an important component of Human Powered Aircraft (HPA) propulsion system. HPA uses large diameter low rotational speed propeller to get high propeller efficiency. The propeller was designed by HPA propeller designing program. The propeller pitch is adjustable by rotating the blade axis angle at ground. Performance of the propeller for various parameters are analysed by the same program used for design. Off-design condition performance was also checked including pilot power change and flight speed change. The propeller was manufactured in ultra-light structure using carbon composite material down to 950g. The propeller was ground tested on ironbird and installed on KARI HPA. Finally the HPA flew 291m with this propeller.

• Journal of the Korea Institute of Military Science and Technology
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• v.26 no.3
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• pp.302-312
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• 2023

This paper describes the analysis of lightning strike zoning, the indirect lightning data simulation and the protection design for lightning indirect effects of equipment by lightning strike for unmanned aircraft consisting of composite wings. Through the analysis of lightning strike zoning according to the external shape of unmanned aerial vehicles, the structure areas that should be protected during lightning strike is derived, and the protection requirements of lightning indirect effects for flight critical equipments and equipment that must be operated upon lightning strike was derived. Lightning protection levels according to the location of mounting equipment and surrounding structure materials for each equipment was derived, and the protection design of the unmanned aerial vehicle with composite structures was also proposed from direct effect of lightning. Later, the lightning protection technology will be verified by the ground test of lightning direct and indirect effects.

• Korean Journal of Materials Research
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• v.10 no.5
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• pp.354-659
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• 2000

Applications of composite materials have been in progress noticeably in manufacturing areas of automotive, aircraft and in other industries, resulting in ensuing research activities. Carbon-epoxy, one of major composite materials, is investigated for its thermal characteristics. Upon treatments of the composite material with repeated heatings and coolings variations of its elastic constants are monitored to reveal the thermal nature of the composite material. In this study, generally, changes in elastic constants are observed to occur mostly during the first 10~20 thermal cycles. Values of G(sub)13 remain almost unchanged except a minor decrease. However in the observed small changes thermal shocks produce less effect than thermal fatigues. On the other hand, values of $E_1$show gradual increases with the num-ber of applied thermal cycles and temperatures. Meanwhile, values of $E_2$ and G(sub)23 decrease to a certain extent in the early stage during the applications of thermal cycling but are not appreciable affected by frequencies of thermal cy-cles. Also, thermal shocks are observed to induce different effects depending on treatment temperatures.

• Journal of Korea Port Economic Association
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• v.23 no.2
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• pp.25-40
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• 2007

The sea/air intermodal transport is a time-saving and cost-saving transport for cargo shipments. In reaction to a recent growth of high value-added products in China, the volume of sea/air intermodal transport in Korean airport has been increasing continuously. This paper treats the situation, the system, and the possibility of sea/air intermodal transport, which are emerging as an alternative to solve the logistics problem related to the increase of international air cargo demand in China. Also, several strategies are considered to develope Korea into intermodal transport hub including the value added logistics activity which will secure the demand of sea/air intermodal transport.