• 한국방재학회 논문집
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• 제8권5호
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• pp.65-70
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• 2008

변형과 파손 등의 공용성능 문제가 발생하고 있는 아스팔트 포장과 콘크리트 포장에 비해 내구성능이 우수한 에폭시와 세라믹스를 결합한 혼합물을 도로포장에 적용하기 위하여 실내물성실험을 수행하고 현장에 적용하였다. 본 연구는 부착력과 내구성이 뛰어나 구조물 보수, 보강에 널리 사용되는 에폭시를 도로포장에 적용하기 위해서 세라믹스와 금속성분 등의 micro powder를 첨가하여 포장 재료로써의 공용성능을 확인하고 이를 현장에 적용하여 작업성과 시공성 등을 확인하였다. 콘크리트포장 현장의 시험시공은 파손된 기존 포장구간에 면처리 후 7 mm 박층으로 시공하였고, 아스팔트포장 현장의 시험시공은 파손된 기존 포장구간에 면처리 후 15 mm 박층으로 시공하여, 12개월 가량 균열 및 변형 발생여부를 관찰하였다. 에폭시와 세라믹스를 결합한 혼합물은 기존 포장과의 부착력이 뛰어났으며, 변형과 파손에 대한 저항성이 기존 포장재료에 비해 우수한 것으로 나타나 이를 도로현장에 적용할 경우, 공용성능 및 공용년한의 향상이 기대된다.

• Composites Research
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• 제25권6호
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• pp.178-185
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• 2012

본 연구에서는 기능성 나노복합재를 제작하는 방법이 제시되었다. 미소 입자들을 포함하고 있는 점성을 가진 유체에 전기장을 가하여 유체속에 포함된 입자들을 전기장의 방향에 따라 규칙적으로 배열을 하였다. FAiMTa 기술이라고 불리는 이 방법은 마이크로 혹은 나노 사이즈의 입자들을 체인의 형태로 배열하여 직교이방성 폴리머 나노복합재의 제작을 가능하게 하였다. 알루미나($Al_2O_3$), 탄소나노튜브(CNT), 탄소(Graphite), 텅스텐(W) 등의 마이크로 혹은 나노 사이즈 입자 분말을 사용하여 FAiMTa기술의 유효성을 확인하는 시험을 수행하였다. 이러한 입자들을 전기장을 사용하여 일정한 방향으로 배열하여 직교이방성 폴리머 복합재를 만들었고, 시험시편의 물리적 특성 즉 기계적 열적 특성을 측정하여 방향성을 확인하였다. 이렇게 제작된 첨단 나노복합재는 각종 산업분야에서 큰 효과가 기대된다.

• Current Photovoltaic Research
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• 제3권1호
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• pp.5-9
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• 2015

Absorption and luminescence characteristics of disperse red-19 (DR-19) and $TiO_2$ composite have been investigated with various poling electric field strengths. Two step synthetic processes were employed to employ the DR-19 to the $TiO_2$ sol-gel. Firstly, urethane bond formation between DR-19 (-OH) and 3-isocyanatopropyl triethoxysilane (ICPTES, -N=C=O) performed (ICPDR) prior incorporation to the $TiO_2$ sol-gel. Secondary, the hydrolysis of the ethoxy group from the ICPTES and condensation reaction between silanol groups from ICPTES and $TiO_2$ sol-gel were performed. The ICPDR and $TiO_2$ sol-gel ($DRTiO_2$) were mixed and stirred for several days. The composite was coated to the ITO coated glass substrate. Corona poling were performed before drying the composite with various electric field strengths. The absorption intensity decreased with the increase of the poling field strength, which resulted in the increase of poling efficiency. The photoluminescence also decreased as the poling field strength increased. There is long luminescence tail for the poled $DRTiO_2$ film compared with unpoled $DRTiO_2$ film. The luminescence long tail indicates that the self-trapped excitons and polarons were generated when the $DRTiO_2$ film was poled with electric field.

• 한국소음진동공학회논문집
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• 제11권6호
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• pp.200-207
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• 2001

In this paper, a new method for Partial field decomposition is developed that is based on the beamforming algorithm for the application of acoustical holography to a composite sound field generated by multiple incoherent sound sources. In the proposed method, source Positions are first predicted by MUSIC(multiple signal classification) algorithm. The composite sound fields can then be decomposed into each partial field by the beamforming. Results of both numerical simulations and experiments show that the method can find each partial field very accurately and effectively, and that it also has Potential to be used for application to distributed sources.

• Steel and Composite Structures
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• 제26권4호
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• pp.513-531
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• 2018

In this article, static, buckling and free vibration analyses of a sinusoidal micro composite beam reinforced by single-walled carbon nanotubes (SWCNTs) with considering temperature-dependent material properties embedded in an elastic medium in the presence of magnetic field under transverse uniform load are presented. This system is used at micro or sub micro scales to enhance the stiffness of micro composite structures such as bar, beam, plate and shell. In the present work, the size dependent effects based on surface stress effect and modified strain gradient theory (MSGT) are considered. The generalized rule of mixture is employed to predict temperature-dependent mechanical and thermal properties of micro composite beam. Then, the governing equations of motions are derived using Hamilton's principle and energy method. Numerical results are presented to investigate the influences of material length scale parameters, elastic foundation, composite fiber angle, magnetic intensity, temperature changes and carbon nanotubes volume fraction on the bending, buckling and free vibration behaviors of micro composite beam. There is a good agreement between the obtained results by this research and the literature results. The obtained results of this study demonstrate that the magnetic intensity, temperature changes, and two parameters elastic foundations have important effects on micro composite stiffness, while the magnetic field has greater effects on the bending, buckling and free vibration responses of micro composite beams. Moreover, it is shown that the effects of surface layers are important, and observed that the changes of carbon nanotubes volume fraction, beam length-to-thickness ratio and material length scale parameter have noticeable effects on the maximum deflection, critical buckling load and natural frequencies of micro composite beams.

• 한국전자파학회지:전자파기술
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• 제5권1호
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• pp.31-39
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• 1994

다양한 복합재료의 평면 전자파 차폐효과를 플랜지형 동축선 측정치구를 사용하여 평가하였다. 이들 측정결과로부커 제품의 외장재로 사용할 다양한 차폐재료의 선택 우선순의를 결정할 수 있다. 전자파차폐기능 복합재료의 차페 성능은 재료에 포함된 급속분말이나 급속섬유의 종류와 함량에 크게 의존한며, 최적 함량의 결정과 최적 첨가재의 선택이 매우 중요함을 알았다.

• 한국소음진동공학회논문집
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• 제22권8호
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• pp.791-799
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• 2012

In this paper free vibration analysis of symmetric and cross-ply elastic laminated shells based on FSDT was performed through discretization of equations of motion and boundary condition. Structural model of laminated composite cylindrical shells subjected to a combination of magnetic and thermal fields is developed via Hamilton's variational principle. These coupled equations of motion are based on the electromagnetic equations(Faraday, Ampere, Ohm, and Lorenz equations) and thermal equations which are involved in constitutive equations. Variations of dynamic characteristics of composite shells with applied magnetic field, temperature gradient, and stacking sequence are investigated and pertinent conclusions are derived.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2002년도 추계학술발표대회 논문집
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• pp.71-74
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• 2002

A higher-order zig-zag theory is developed to refine the predictions of natural frequency and mode shape of laminated composite plates with multiple delaminations. By imposing top and bottom surface transverse shear stress-free and interface continuity conditions of transverse shear stresses including delaminated interfaces, the displacement field with minimal degree-of-freedoms are obtained. This displacement field can systematically handle the number, shape, size, and locations of delaminations. Through the dynamic version of variational approach, the dynamic equilibriums and variationally consistent boundary conditions are obtained. Through the numerical example of natural frequency analysis, the accuracy and efficiency of present theory are demonstrated. The present theory is suitable as an efficient tool to analyze the static and dynamic behavior of the composite plates with multiple delaminations.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2012년도 춘계학술대회 논문집
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• pp.748-754
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• 2012

In this paper free vibration analysis of symmetric and cross-ply elastic laminated shells based on FSDT was performed through discretization of equations of motion and boundary condition. Model of laminated composite shells subjected to a combination of magnetic and thermal fields is developed. These coupled equations of motion are based on the electromagnetic equations (Faraday, Ampere, Ohm, and Lorenz equations) and thermal equations which are involved in constitutive equations. Dynamic characteristic of composite shells for change of magnetic fields is investigated.

• 한국생산제조학회지
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• 제6권3호
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• pp.89-95
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• 1997

A simulation to investigate the thermal behavior in short fiber or whisker reinforced composite materials has been performed for the application to the thermoelastic stress analysis using Finite Element Method (FEM). To obtain the internal field quantities of composite material, the procedure of micromechanical modeling and the principle of virtual work were implemented. For the numerical illustration, an aligned axisymmetric single fiber model has been employed to assess field quantities. It was found that the proposed simulation methodology for thermoelastic stress analysis is applicable to the complicated inhomogeneous solid for the investigation of micromechanical thermoelastic behavior.