• Steel and Composite Structures
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• 제49권6호
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• pp.633-643
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• 2023

In this study, the natural frequencies of Functional Graded Materials (FGM) plates are predicted using Artificial Neural Network (ANN). A model based on Third-order Shear Deformation Theory (TSDT) and FEM is used to train the ANN model. Different training methods are tested to simulate input and output dependency. As this is a parametric model, several architectures and optimization algorithms were tested. The proposed model allows us to minimize the CPU time to evaluate candidate material properties for FGM plate material selection and demonstrate their influence on dynamic behavior. Consequently, the time required for the FGM design process (candidate materials for material selection) and the geometric optimization of the FGM structure would remain reasonable. The ANN model can help industries to produce FGM plates with good mechanical properties of the selected materials. I addition, this model can be used to directly predict vibration behavior by testing a large number of FGM plates, representing all possible combinations of metals and ceramics in today's industry, without having to solve any eigenvalue problems.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2003년도 추계학술발표강연 및 논문개요집
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• pp.57-57
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• 2003

High dielectric constant materials (high K) have attracted a great deal of interest because of the dramatic scaling down of DRAM capacitor reaching its physical limit in terms of reduction of thickness. Among high-K materials that can replace silicon dioxide, tantalum pentoxide (Ta2O5) thin film, with their high dielectric constant (∼25) and good step coverage, is the candidate of choice.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2004년도 추계학술발표대회 논문집
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• pp.232-235
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• 2004

This is the preliminary study to develop composite window frame of commercial aircraft using VaRTM process. For two candidate carbon fabric(triaxial fabric, sleeving braider dry carbon fiber), specimens were fabricated using VaRTM process ,and then the physical & mechanical tests were performed to gain material property according to ASTM. FEM analysis for each candidate carbon fabric were performed to find the minimum ply number and weight for composite window frame. In this study Tsai-Wu strength failure criteria was utilized to evaluate the safety of structure.

• Nuclear Engineering and Technology
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• 제55권3호
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• pp.1191-1198
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• 2023

Bentonite buffer material is a critical component in an engineered barrier system (EBS) for disposing high-level radioactive waste (HLW). The bentonite buffer material protects the disposal canister from groundwater penetration and releases decay heat to the surrounding rock mass; thus, it should possess high thermal conductivity, low hydraulic conductivity, and moderate swelling pressure to safely dispose the HLWs. Bentonite clay is a suitable buffer material because it satisfies the safety criteria. Several additives have been suggested as mixtures with bentonite to increase the thermal-hydraulic-mechanical-chemical (THMC) properties of bentonite buffer materials. Therefore, this study investigated the geotechnical, mineralogical, and THMC properties of several candidate additives such as sand, graphite, granite, and SiC powders. Datasets obtained in this study can be used to select adequate additives to improve the THMC properties of the buffer material.

• 대한화학회지
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• 제63권3호
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• pp.151-159
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• 2019

본 연구는 밀도 범함수 이론(DFT) 가운데 하나인 B3LYP 방법을 $6-31G^{**}$, cc-pVDZ, cc-pVTZ의 바탕함수 집합(basis set)과 함께 사용하여 전자 공여성 분자(D)로 카바졸(carbazol) 그리고 전자 구인성 분자(A)로 dicyanobenzene, diphenyl sulfone, benzonitrile 등의 조합으로 이루어진 열 활성화 지연형광(TADF) 후보 물질에 대하여 분자구조를 최적화하고 진동주파수를 계산하였다. 또한 최적화된 분자 구조에 대하여 HOMO와 LUMO 에너지 차이를 계산하였으며, 나아가 시간 의존 밀도 범함수 이론(TD-DFT)을 사용하여 분자의 최대 흡수 및 방출 파장(${\lambda}_{max}$) 그리고 단일항과 삼중항 들뜬 상태의 에너지 차이(${\Delta}E_{ST}$) 등을 계산하여 열 활성 지연형광(TADF) 소재로서의 가능성을 예측하였다.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part2
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• pp.896-897
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• 2006

In the viewpoint of engineering, materials problem is a key problem, which determines whether the exploitation of fusion energy will be success. The most important class of fusion materials is plasma-facing materials (PFM). W, as high Z high melting-point metal is one of the most important candidate materials due to its high plasma erosion resistance. Improving the ductility of W and W based alloy, lowering its ductile-brittleness transition temperature for meeting the requirements of fusion application is an important task. In this paper, severalpowder meatllurgy methods of fabricating W and W based materials are being investigated.

• Nuclear Engineering and Technology
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• 제37권5호
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• pp.423-432
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• 2005

Japanese activities on fusion structural materials R&D have been well organized under the coordination of university programs and JAERI/NIMS programs more than two decades. Where, two categories of structural materials have been studied, those are; reduced activation martensitic/ferritic steels (RAFs) as reference material and vanadium alloys and SiC/SiC composite materials as advanced materials. The R&D histories of these candidate materials and the present status in Japan are reviewed with the emphasis on materials behavior under radiation damage. The importance of IFMIF and technology development for blanket R&D including ITER-TBRG activity is emphasized and the current status of those activities in Japan is also presented.

• 한국섬유공학회:학술대회논문집
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• 한국섬유공학회 2003년도 The Korea-Japan Joint Symposium
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• pp.7-8
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• 2003

Since PVDF/poly(1,4-butylene adipate) blend shows much lower LCST curve compared with PVDF/PMMA blend, the PVDF/PBA blend can be a good candidate for investigating the effect of the electric field on the phase separation and dissolution behavior of an electro-active polymer and electro-inactive polymer blend. (omitted)

• 지질공학
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• 제9권2호
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• pp.89-100
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• 1999

핵폐기물 처분장 공학방벽재로서의 우리나라 제 3 기층에서 산출되는 벤토나이트와 제올라이트의 활용 가능성을 물리화학적 특성을 중심으로 평가하였다. 연일 및 감포일대 제 3 기층의 9개 대표적인 벤토나이트 광산과 6개의 제올라이트 광산에서 채취한 자연산 시료와 관련회사의 추천상품시료에 대해 X-선 회절 분석, 팽윤도 측정, 양이온교환능 측정, 비표면적 측정, 몬모릴로나이트의 함량계산, 유기탄소함량 분석, 시차 열분석(DTA), 편광현미경 관찰, 주사전자현미경(SEM)관찰 및 전자현미분석(EPMA)을 실시하여 각 분석항목을 비교 평가하였다. 연구결과를 종합하면 U-41 및 G-46의 광산에서 산출되는 벤토나이트와 대도 및 Y-1호 광산의 제올라이트가 인공방벽재료로 갖추어야할 물리화학적 특성이 최적인 것으로 평가된다.

• Transactions on Electrical and Electronic Materials
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• 제14권4호
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• pp.187-192
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• 2013

Because of the importance of small target detection in infrared images, many studies have been carried out in this area. Using a Kalman filter and mean shift algorithm, this study proposes an algorithm to track multiple small moving targets even in cases of target disappearance and appearance in serial infrared images in an environment with many noises. Difference images, which highlight the background images estimated with a background estimation filter from the original images, have a relatively very bright value, which becomes a candidate target area. Multiple target tracking consists of a Kalman filter section (target position prediction) and candidate target classification section (target selection). The system removes error detection from the detection results of candidate targets in still images and associates targets in serial images. The final target detection locations were revised with the mean shift algorithm to have comparatively low tracking location errors and allow for continuous tracking with standard model updating. In the experiment with actual marine infrared serial images, the proposed system was compared with the Kalman filter method and mean shift algorithm. As a result, the proposed system recorded the lowest tracking location errors and ensured stable tracking with no tracking location diffusion.