• Journal of the Korean Society for Nondestructive Testing
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• v.25 no.4
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• pp.274-286
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• 2005

Fracture behaviors and acoustic emission (AE) characteristics of single-edge-notched monolithic aluminum plates and glass fiber/aluminum hybrid laminate plates have been investigated under tensile loads. AE signals from monolithic aluminum could be classified into two different types: signals with low frequency band and high frequency band. High frequency signals were detected in the post stage of loading beyond displacement of 0.45mm. For glass fiber/aluminum laminates, AE signals with high amplitude and long duration were additionally confirmed on FFT frequency analysis, which corresponded to macro-crack propagation and/or delamination between A1 and fiber layers. On the basis of the above AE analysis and fracture observation with optical microscopy and ultrasonic T scan, characteristic features of AE associated with fracture processes of single-edge-notched glass fiber/aluminum laminates were elucidated according to different fiber ply orientations.

• Journal of Korean Society of Environmental Engineers
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• v.35 no.11
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• pp.815-820
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• 2013

The purpose of this research is to prepare the aluminum electrode coated with activated carbon for removing air pollution dust. The experiments were studied on the selection of optimal polymer for binding aluminum plate with powdered activated carbon, preventing the pore blocking of activated carbon from polymer binder, and the dust treatability for the prepared activated carbon electrode. The optimal adhesive for coating activated carbon on an electric aluminum plate was polyvinyl acetate (PVA) with vinyl functional group. For the opening of the blocked pore with polymer, it was very effective to embed polymer solvent in pore of activated catbon firstly before mixing activated carbon with PVA, and then to devolatilize the embedded solvent of carbon pore at high temperature. The mass of trapped dust on aluminum electrode coated with activated carbon was about double of the trapped one on just aluminum electrode.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.11a
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• pp.278-281
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• 2009

The performance of aluminum bipolar plates was evaluated for the lightweight fuel cell system as a power source for a small reconnaissance UAV. Higher performance per weight was obtained from aluminum bipolar plates than the graphite bipolar plates. To check the influence of operating temperature, the performance of a single cell using aluminum bipolar plates was evaluated at 40 / 50 / $60^{\circ}C$. When dry hydrogen and air were used, the finest performance was obtained at $40^{\circ}C$, a lower operating temperature compared with usual operating temperatures.

• Proceedings of the Korean Nuclear Society Conference
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• 1996.05d
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• pp.253-258
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• 1996

원자로의 가동 중지 중이나 재장전시 원자로가 설치되어 있는 수조의 냉각수가 증기발생기 안으로 유입되는 것을 막는 장비로써 노즐댐을 사용한다. 현재의 노즐댐은 알루미늄 재질로 그 무게가 무거워 노즐댐 작업자가 취급하기 어렵다. 이 노즐댐의 경량화와 동시에 구조적 강도를 증가시키기 위해서 비강성이 높은 탄소섬유 강화 복합재료와 굽힘 강성 및 전단강성을 증가시키기 위하여 벌집구조(honeycomb)의 알루미늄을 사용하여 KAERI 노즐댐-II를 설계하였다. 노즐댐에 발생하는 응력 해석을 통하여 중앙판과 측면판의 변위가 충분히 작은 값을 가지면서 파괴지수도 충분히 작은 값이 되는 탄소섬유의 적층각도를 구하였으며, 중앙판은 ［$\pm$15］로 적층하고 측면판은 ［$\pm$45 ］로 적층 하였다. 그리고 각 판의 최대 파괴지수는 중앙판의 경우 0.32, 측면판의 경우 0.27 이었고 최대변위는 각각 3.1mm, 2.7mm로 노즐댐을 사용할 때 예상되는 하중에 대하여 노즐댐의 구조적 건전성을 입증하였다.

• Journal of the Society of Naval Architects of Korea
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• v.33 no.4
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• pp.106-123
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• 1996

This paper experimentally investigates the characteristics of Al-honeycomb sandwich panels which are considered as a promising primary strength member of weight critical large structures. Some tests on the aluminum honeycomb panels subject to 3-point bending or uniaxial compression or crushing load are carried out. Based on the test results, linear elastic response, buckling/ultimate strength and crushing/energy absorption capacity are discussed. Some guidelines for design of aluminum honeycomb panels are given.

• Journal of radiological science and technology
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• v.38 no.3
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• pp.187-197
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• 2015

This study analysed the effectiveness of aluminium(Al) filter in the added compound filtration for the removal of characteristic radiation by energy spectrum and image evaluation. 0.1, 0.2, 0.3 mm copper with and without 1 mm Al were evaluated. The energy spectrum was measured using the GATE and evaluated separately by each energy. Image quality was evaluated by PSNR, MAE, MSE, CNR, SNR and qualitative analysis was performed by seven items for resolution and contrast from chest x-ray criteria of National Cancer Screening and Cardiovascular evaluation table. In the analysis of the quality of the energy per photon spectrum with the exception of a low energy region, without Al were superior in all area. PSNR MAE, MSE, CNR, SNR and qualitative analysis were the same or slightly better. PSNR was over 30 dB and all significant and the p>0.05 in the T-test of qualitative analysis. The energy spectrum and image quality have little difference between before and after use of Al filter. Therefore, it is effective to use the Al filter for the radiation dose management with the compensation capability of DR system.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2015.11a
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• pp.305-305
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• 2015

알루미늄 방열판 위에 MPCVD(Microwave Plasma Enhanced Chemical Vapor Deposition) 장치를 이용하여 DC 바이어스 전압을 기판에 인가하면서 $Ar+CH_4$ 가스 분위기에서 증착한 나노결정질 다이아몬드(Nanocrystalline Diamond; NCD) 박막의 방열 특성을 평가하였다. XRD와 Raman spectroscopy를 이용하여 증착된 박막이 NCD인지를 확인하였으며 FE-SEM 및 FIB로 박막의 표면 및 단면의 형상을 관찰하였다. 다이아몬드가 증착된 방열판에 LED를 부착하여 발열시키고 열유동측정기의 하나인 T3-ster를 사용하여 방열 특성을 분석하였다. 기존 알루미늄(Al) 기판(5.55 K/W)보다 다이아몬드 증착(Dia-Al) 기판(3.88 K/W)의 열저항 값이 현저히 작았다, 또한 LED 접합온도는 Dia-Al 기판이 Al 기판보다 약 $3.5^{\circ}C$만큼 낮았다. 적외선 열화상 카메라로 발열 중인 시편의 전면과 후면을 촬영한 결과, LED가 부착된 전면부에서는 최고 발열 부위(hot spot)의 면적이 Al 기판의 경우가 Dia-Al 기판보다 높았고, 후면부에서는 그 반대의 경향을 보였다. 이들 데이터로부터 다이아몬드 증착 방열판이 기존의 방열판보다 방열특성이 우수한 것으로 해석할 수 있으며, 다이아몬드 박막을 방열판으로 사용하면 LED의 사용 수명과 효율이 높아질 것으로 기대된다.

• Progress in Medical Physics
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• v.27 no.2
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• pp.55-63
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• 2016

We studied the method to gain a clear LSF using a thick aluminum sheet and to acquire the spatial resolution value with a high accuracy for a low spatial resolution imaging modality. In this study, aluminum sheets with thicknesses varying from 0.3 mm to 1.2 mm were tested to derive a modulation transfer function (MTF) for the oversampling and non-oversampling methods. The results were evaluated to verify the feasibility of the use of thick sheets for periodic quality assurance. Oversampling was more accurate than non-oversampling, and an aluminum sheet with a correction factor less than 2 at the cut-off frequency, which was less than 0.8 mm in this case, was confirmed to be suitable for MTF measurements. Therefore, MTF derivation from a thick aluminum sheet with thickness correction is plausible for a medical imaging modality.

• Journal of Ocean Engineering and Technology
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• v.23 no.6
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• pp.117-123
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• 2009

This paper presents a numerical simulation of guided ultrasonic waves propagating in aluminum-epoxy-aluminum adhesive plates. In particular, this study investigated the effect of the epoxy thickness on the dispersive patterns, such as the phase velocity and group velocity of guided ultrasonic waves. In addition to investigating the dispersive curves, a numerical simulation using the pulse-echo method was carried out. This simulation showed that the degree of sensitivity of the epoxy thickness is dependent on the curvature of the phase and group dispersion curves, the maximum amplitude of the received time signals, and the peak frequency of the real components of the Fourier transform. Then, the linear relations between the epoxy thickness and the received and transformed signals were constructed to estimate the epoxy thickness.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2009.04a
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• pp.304-307
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• 2009

본 논문에서는 3차원 모델링을 이용하여 원공을 갖는 알루미늄 판의 패치 보강효과에 대해 알아보고자 한다. 구조물의 노후화로 인해 높은 응력을 받는 부재의 응력 특이점에서 내구력이 급격하게 저하되거나 때로는 부재의 정적파괴를 유발시키는 원인을 제공한다. 이로 인해 과거에는 손상된 모재에 보강 재료를 연결시키기 위하여 리벳 또는 볼트와 같은 기계적 연결을 통해 보강하였으나 최근에는 접착패치보강 기법이 그 주류를 이루고 있다. 패치 보강시 일면 패치 보강으로 인하여 면외 휨 효과가 발생된다. 판의 두께 방향에 따른 응력집중계수를 별도로 분석하였다. 기존의 3차원 솔리드 요소는 해의 정확성은 뛰어난 반면에 상당한 컴퓨터 시간을 요구하는 단점을 가지고 있다. 이러한 문제를 극복하기 위해서, 본 논문에서는 각 층의 변위장을 2차원 형상함수와 1차원 형상함수의 조합으로 구성하여, 면내거동에 대한 p-세분화와 면외거동에 대한 p-세분화를 분리시키는 방식을 취한다. 또한, 에너지 함수의 적분시 Gauss-Lobatto 적분법을 사용하여 절점의 위치에서의 응력점을 구하는 경우, 외삽과정을 계산하는 단계를 생략하면서도, 해의 정확성 측면에서는 거의 차이가 없기 때문에 좀 더 효율적인 수치적분이 될 수 있다.