• Steel and Composite Structures
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• 제38권6호
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• pp.671-690
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• 2021

Seismic responses of RC core wall with two outriggers are investigated in this study. In the models analyzed here, one of the outriggers is fixed at the top of the building and the second is placed at different levels along the height of the system. Each of the systems resulting from the placement of the outrigger at different locations is designed according to the prescriptive codes. The location of the outrigger changes along the height. Linear design of all the structures is accomplished by using prescriptive codes. Buckling restrained braces (BRBs) are used in the outriggers and forward directivity near fault and far fault earthquake record sets are used at maximum considered earthquake (MCE) level. Results from nonlinear time history analysis demonstrate that BRB outriggers can change the seismic responses like force distribution and deformation demand of the RC core-walls over the height and lead to the new plastic hinge arrangement over the core-wall height. Plasticity extension in the RC core wall occurs at the base as well as adjacent to the outrigger levels. Considering the maximum inter-story drift ratio (IDR) demand as an engineering parameter, the best location for the second outrigger is at 0.75H, in which the maximum IDR at the region upper the second outrigger level is approximately equal to the corresponding value in the lower region.

• 전기화학회지
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• 제23권2호
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• pp.39-46
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• 2020

이차전지용 전극은 일반적으로 전극 활물질, 도전재, 그리고 고분자 바인더가 혼합된 복합 전극의 형태를 갖는다. 따라서, 크기나 형태가 다른 각 성분의 조성 및 전극 내 분포에 따라 전극의 전기화학적 활성이 달라지게 되나, 이를 효율적으로 예측하고 설계하는 3차원 전극 구조 모델링 기술은 아직 활발히 연구되고 있지 못하다. 따라서, 본 논문에서는 3차원 구조 모델링 툴인 GeoDict를 이용하여, LiCoO₂ 전극 활물질 입자 크기와 복합 전극 밀도에 따른 입자 간 접촉 면적과 전기전도특성을 예측한 결과를 제시한다. 전극의 조성과 로딩은 LiCoO₂ : Super P Li^® : Polyvinylidene Fluoride (PVdF) = 93 : 3 : 4 (wt%)과 13 mg cm^-2로 고정하고, LiCoO₂ 평균 입경은 10 ㎛과 20 ㎛로 전극 밀도는 2.8 g cm^-3, 3.0 g cm^-3, 3.2 g cm^-3, 3.5 g cm^-3, 4.0 g cm^-3로 제어하여 가상의 3차원 전극 구조를 만들었다. 이 구조를 활용하여 LiCoO₂ 입경 증가에 따른 입자 간 접촉 면적 감소와 전기전도특성 증가 경향성이 정량화되었다. 또한, 전극 밀도가 증가함에 따라 입자 간 접촉 면적 및 전기전도특성 향상도 수치화 된 값으로 예상될 수 있다. 따라서, 본 논문에서는 3차원 전극 구조 분석 기법을 이용하면, 더 효율적인 복합 전극 설계가 가능함을 제시한다.

• Structural Monitoring and Maintenance
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• 제10권4호
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• pp.315-337
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• 2023

During the design phase, it is crucial to determine the interface stresses between the reinforcing plate and the concrete base in order to predict plate end separation failures. In this work, a simple theoretical study of interface shear stresses in beams reinforced with P-FGM and E-FGM plates subjected to an arbitrarily positioned point load, or two symmetrical point loads, was presented using the linear elastic theory. The presence of pores in the reinforcing plate distributed in several forms was also taken into account. For this purpose, we analyze the effects of porosity and its distribution shape on the interracial normal and shear stresses of an FGM beam reinforced with an FRP plate under different types of load. Comparisons of the proposed model with existing analytical solutions in the literature confirm the feasibility and accuracy of this new approach. The influence of different parameters on the interfacial behavior of reinforced concrete beams reinforced with functionally graded porous plates is further examined in this parametric study using the proposed model. From the results obtained in this study, we can say that interface stress is significantly affected by several factors, including the pores present in the reinforcing plate and their distribution shape. Additionally, we can conclude from this study that reinforcement systems with composite plates are very effective in improving the flexural response of reinforced RC beams.

• 구강회복응용과학지
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• 제22권3호
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• pp.211-220
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• 2006

Need of porcelain-repair system is largely demanding as dental porcelain restorations are increased in clinical dentistry. This study investigated shear bond strength of commercial porcelain-repair systems on dental porcelain and their reliability. Experimental groups were as follows; Group A Super Bond C&B, Group B Porcelain repair kit, Group C Ceramic repair, and Group D Spectrum system as a control. Porcelain disks were fired and embedded in epoxy resin. Porcelain surface were ground using 220 grit SiC disk, then cleaned in ultrasonic bath. Then porcelain specimens were treated with each repair system. A clear polystyrene cylinder 3.5 mm in internal diameter was filled with composite resin. Then the resin cylinder was polymerized with a visible light curing unit. Thirty one specimens at each group were prepared and stored at $37^{\circ}C$ distilled water for 48 h. Specimens were tested in an Instron testing machine according to ISO TR 11405. Mean shear bond strength and standard deviation of each group was $15.7{\pm}4.1MPa$ (Group A), $12.8{\pm}4.9MPa$ (Group B), $7.2{\pm}3.0MPa$ (Group C) and $9.6{\pm}2.2MPa$ (Group D). ANOVA and Tukey HSD post-hoc test showed that there were significant differences between groups (p<0.05). Data of bond strength were analyzed with two-parameter Weibull distribution. Confidence interval of Weibull modulus (m-parameter) at 95% of Group A (3.5-6.3) and Group D (3.6-6.0) were significantly higher than Group B (2.2-3.7) and Group C (2.0-3.4). There was little correlation between mean shear bond strength and Weibull modulus. Results indicated that acid-etching of porcelain surface increased porcelain-resin shear bonding strength.

• Journal of Microbiology and Biotechnology
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• 제32권5호
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• pp.564-574
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• 2022

Microbial diversity in the soil is responsive to changes in soil composition. However, the impact of soil amendments on the diversity and structure of rare and abundant sub-communities in agricultural systems is poorly understood. We investigated the effects of different Chinese herb residue (CHR) soil amendments and cropping systems on bacterial rare and abundant sub-communities. Our results showed that the bacterial diversity and structure of these sub-communities in soil had a specific distribution under the application of different soil amendments. The CHR soil amendments with high nitrogen and organic matter additives significantly increased the relative abundance and stability of rare taxa, which increased the structural and functional redundancy of soil bacterial communities. Rare and abundant sub-communities also showed different preferences in terms of bacterial community composition, as the former was enriched with Bacteroidetes while the latter had more Alphaproteobacteria and Betaproteobacteria. All applications of soil amendments significantly improved soil quality of newly created farmlands in whole maize cropping system. Rare sub-communitiy genera Niastella and Ohtaekwangia were enriched during the maize cropping process, and Nitrososphaera was enriched under the application of simple amendment group soil. Thus, Chinese medicine residue soil amendments with appropriate additives could affect soil rare and abundant sub-communities and enhance physicochemical properties. These findings suggest that applying soil composite amendments based on CHR in the field could improve soil microbial diversity, microbial redundancy, and soil fertility for sustainable agriculture on the Loess Plateau.

• Membrane and Water Treatment
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• 제15권2호
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• pp.67-78
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• 2024

In this study, a nickel hexacyanoferrate and manganese dioxide-polyacrylonitrile (NM-PAN) composite was synthesized and used for the sorptive removal of Co²⁺, Sr²⁺, and Cs⁺ Cs⁺ in radioactive laundry wastewater. Single- and multi-solute competitive sorptions onto NM-PAN were investigated. The Freundlich (Fr), Langmuir (Lang), Kargi-Ozmıhci (K-O), Koble-Corrigan (K-C), and Langmuir-Freundlich (Lang-Fr) models satisfactorily predicted all the single sorption data. The sorption isotherms were nonlinearly favorable (Freundlich coefficient, N_F = 0.385-0.426). Cs⁺ has the highest maximum sorption capacity (q_mL = 0.855 mmol g^-1) for NM-PAN compared to Co²⁺ and Sr²⁺, wherein the primary mechanism was the physical process (mainly ion-exchange). The competition between the metal ions in the binary and ternary systems reduced the respective sorption capacities. Binary and ternary sorption models, such as the ideal adsorbed solution theory (IAST) model coupled with single sorption models of IAST-Fr, IAST-K-O, IAST-K-C and IAST-Lang-Fr, were fitted to the experimental data; among these, the IAST-Freundlich model showed the most satisfactory prediction for the binary and ternary systems. The presence of cationic surfactants highly affected the sorption on NM-PAN due to the increase in distribution coefficients (K_d) of Co²⁺ and Cs⁺.

• 한국재난정보학회 논문집
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• 제15권4호
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• pp.524-530
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• 2019

연구목적: 본 논문에서는 3차원 해석프로그램을 활용하여 인터페이스 요소를 구성하고, 일반적인 부재의 특성치와 강도가 보강된 부재의 특성치 등의 실제 표현할 수 있는 물성조건을 적용하여 연결체의 복합거동 안정성을 평가하고자 하였다. 연구방법: 해석 모델은 비선형적인 재료 거동을 포함한 솔리드 요소(Solid Element)를 사용하여 빔 구조 및 원형 플랜지, 볼팅 시스템 등의 부재를 설계도면과 동일한 치수로 모델링을 완성하였고 각 부재는 하나의 복합거동연결체로 조립되는 과정에서 다른 요소유형(Element Type) 접촉면의 통일성과 매쉬(Mesh) 생성을 보다 효율적으로 제어하여 분할작업(Partition)을 수행하였으며 부재들에 활용된 강재는 Gr. 50 탄소강 재질로 모델링 하였다. 연구결과: 부재별 접촉 인접부위, 하중재하부위, 고정단 부위, 취약예상부위 등으로 하여 하중단계별 변위 및 변형, 응력상태 등을 나타내고, 유한요소 해석 후 복합거동연결체의 각 하중단계에서의 변위, 변형, 응력 등의 분포도로 영향을 검증하고 설계의 타당성을 확인하였다. 결론: 따라서 이 결과를 토대로 하여 마이크로 파일의 설계 지지력이 결정되면 복합거동 연결체의 취약 지점의 파악과 보강의 정도를 파악할 수 있을 것으로 판단된다.

• Restorative Dentistry and Endodontics
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• 제34권1호
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• pp.69-79
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• 2009

본 연구의 목적은 근관치료 된 치아를 구조와 물성이 다른 post와 core 그리고 전장관으로 수복한 후 과도한 교합하중을 가했을 때 치아에 나타나는 응력분포를 조사하기 위함이다. 발치 된 상악 제2소구치를 micro-CT로 단층촬영하고 3D Doctor로 윤곽선을 추출한 다음 HyperMesh Ver. 6으로 삼차원 치아모형을 만들고 다음과 같은 세 가지 방법으로 수복한 유한요소모형을 제작하였다. 1) 스테인레스 스틸 포스트와 복합레진 코어 그리고 도재소부전장금관으로 수복한 모형. 2) fiber 포스트와 복합레진 코어 그리고 전부도재관으로 수복한 모형 3) 포스트, 코어와 전장관이 일체형인 간접복합레진 EndoCrown으로 수복한 모형 형성된 모형의 협측 또는 설측교두에 500N의 하중을 가하였으며 하중의 방향은 치아 장축에 대해 45도 이었다. 치관부와 치근부의 von Mises 응력을 ANSYS 9.0프로그램으로 분석한 결과 포스트와 코어의 형태보다는 전장관 재료의 탄성 계수가 근관치료된 상악 소구치의 응력분포를 좌우하였다. 치관부에서는 재료의 탄성계수가 높은 전 장관으로 수복한 모형이 낮은 응력분포를 보였다. 치근부에서는 재료의 탄성계수가 낮은 전 장관으로 수복한 모형 이 낮은 응력분포를 보였다.

• Composites Research
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• 제18권4호
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• pp.14-20
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• 2005

방향족아민 경화제의 벤젠링 사이의 관능기 변화가 반응특성, 기계적특성 및 열적특성에 미치는 영향을 고찰하기 위하여 범용 에폭시수지인 DGEBF와 방향족아민 경화제 DDM, DDS 각각을 1:1의 당량비로 혼합하여 동일한 조건으로 경화하였다. 그 결과 에폭시수지 경화물의 특성은 경화제의 벤젠링 사이의 관능기 구조에 따라 매우 큰 영향을 받았다. 즉, 벤젠링 사이에 길이가 길고 bulky한 술폰기를 포함한 DDS는 반응성, 열안정성, 밀도, shrinkage($\%$), 선팽창계수, 인장탄성율. 인장강도, 굴곡탄성율, 굴곡강도의 값이 벤젠링 사이에 메틸기를 가지는 DDM 경화물계 보다 높게 나타났지만, epoxide기의 전환율, 유리전이온도의 값은 낮게 나타냈다. 이것은 술폰기의 강한 전기음성도와 메틸기의 전기 양성적인 repulsive한 성질의 차이에 의한 영향인 것으로 판단된다. 굴곡 파단면의 관찰 결과는 DDS 경화물계의 각개 grain이 불규칙적으로 분포되어 있음을 확연하게 보여준다.

• Smart Structures and Systems
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• 제15권6호
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• pp.1393-1410
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• 2015

An original sensor system based on Fiber Bragg Gratings (FBG) for the strain monitoring of an adaptive wing element is presented in this paper. One of the main aims of the SARISTU project is in fact to measure the shape of a deformable wing for performance optimization. In detail, an Adaptive Trailing Edge (ATE) is monitored chord- and span-wise in order to estimate the deviation between the actual and the desired shape and, then, to allow attaining a prediction of the real aerodynamic behavior with respect to the expected one. The integration of a sensor system is not trivial: it has to fit inside the available room and to comply with the primary issue of the FBG protection. Moreover, dealing with morphing structures, large deformations are expected and a certain modulation is necessary to keep the measured strain inside the permissible measure range. In what follows, the mathematical model of an original FBG-based structural sensor system is presented, designed to evaluate the chord-wise strain of an Adaptive Trailing Edge device. Numerical and experimental results are compared, using a proof-of-concept setup. Further investigations aimed at improving the sensor capabilities, were finally addressed. The elasticity of the sensor structure was exploited to enlarge both the measurement and the linearity range. An optimisation process was then implemented to find out an optimal thickness distribution of the sensor system in order to alleviate the strain level within the referred component.