• Structural Engineering and Mechanics
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• 제76권2호
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• pp.175-191
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• 2020

In this study, the effect of Nano silica (SiO2) on the buckling strength of the glass fiber reinforced laminates containing the machining process causes holes were investigated. The tests have been applied on two status milled and non-milled. To promote the mechanical behavior of the fiber-reinforced glass epoxy-based composites, Nano sio2 was added to the matrix to improve and gradation. Nano sio2 is chosen because of flexibility and high mechanical features; the effect of Nanoparticles on surface serenity has been studied. Thus the effect of Nanoparticles on crack growth and machining process and delamination caused by machining has been studied. We can also imply that many machining factors are essential: feed rate, thrust force, and spindle speed. Also, feed rate and spindle speed were studied in constant values, that the thrust forces were studied as the main factor caused residual stress. Moreover, entrance forces were measured by local calibrated load cells on machining devices. The results showed that the buckling load of milled laminates had been increased by about 50% with adding 2 wt% of silica in comparison with the neat damaged laminates while adding more contents caused adverse effects. Also, with a comparison of two milling tools, the cylindrical radius-end tool had less destructive effects on specimens.

• Asian-Australasian Journal of Animal Sciences
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• 제14권6호
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• pp.862-879
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• 2001

The walls of all higher plants are organized as a cellulosic, fibrillar phase embedded in a matrix phase composed of non-cellulosic polysaccharides, some proteins and, in most secondary walls, lignin. At the effective utilization of plant biomass, qualitative and quantitative analyses of plant cell walls are essential. Structural features of individual components are being clarified using newly developed equipments and techniques. However, "empirical" procedures to elucidate plant cell walls, which are not due to scientific definition of components, are still applied in some fields. These procedures may give misunderstanding for the effective utilization of plant biomass. In addition, interesting the investigation of wall organization is moving towards not only qualitatively characterisation, but also quantitation of the associations between wall components. These involve polysaccharide-polysaccharide and polysaccharide-lignin cross-links. Investigation of the associations is being done in order to understand the chemical structure, organization and biosynthesis of the cell wall and physiology of the plants. Procedures for qualitative and quantitative analyses based on the definition of cell wall components are reviewed focussing in nutritional elucidation of forage grasses by ruminant microorganisms.

• Advances in Computational Design
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• 제1권4호
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• pp.315-327
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• 2016

Damage detection and localisation in structures is essential since it can be a means for preventive maintenance of those structures under service conditions. The use of structural modal data for detecting the damage is one of the most efficient methods. This paper presents comparative performance of various state-of-the-art meta-heuristics for use in structural damage detection based on changes in modal data. The metaheuristics include differential evolution (DE), artificial bee colony algorithm (ABC), real-code ant colony optimisation (ACOR), charged system search (ChSS), league championship algorithm (LCA), simulated annealing (SA), particle swarm optimisation (PSO), evolution strategies (ES), teaching-learning-based optimisation (TLBO), adaptive differential evolution (JADE), evolution strategy with covariance matrix adaptation (CMAES), success-history based adaptive differential evolution (SHADE) and SHADE with linear population size reduction (L-SHADE). Three truss structures are used to pose several test problems for structural damage detection. The meta-heuristics are then used to solve the test problems treated as optimisation problems. Comparative performance is carried out where the statistically best algorithms are identified.

• Journal of Communications and Networks
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• 제8권1호
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• pp.59-69
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• 2006

Bluetooth is reputed as a wireless networking technology supplying ad-hoc networks between digital devices. In particular, Bluetooth scatternet is an essential part of dynamic ad-hoc networks. Yet, there have not been sufficient researches performed on scatternet environment. This paper proposes a scatternet reformation algorithm for ad-hoc networks for instances where some nodes enter or leave the scatternet. The proposed algorithm is a general algorithm that can be applied to many types of Bluetooth scatternet regardless of the topology. The proposed algorithm is made for two reformation cases, i.e., nodes leaving and nodes entering. For the reformation when nodes leave a scatternet, the recovery node vector (RNV) algorithm is proposed. It has short reformation setup delay because the process involves a single page process (not including inquiry process). For the reformation when nodes enter a scatternet, the entry node algorithm is proposed. This is a simple and easily implementable algorithm. In this paper, real hardware experiments are carried out to evaluate the algorithm's performance where the reformation setup delay, the reformation setup probability and the data transfer rate are measured. The proposed algorithm has shown improvement in the reformation setup delay and probability.

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2000년도 추계학술발표대회 및 bio-venture fair
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• pp.421-424
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• 2000

Cartilage injuries are frequent nowadays. The previous surgical treatment of cartilage defect was limited. Another approach in the treatment of cartilage injuries is the use of reconstitute cartilage consisting of chondrocytes cultured in suitable biodegradable scaffolds. Current studies have demonstrated the compatibility of chondrocytes with different biomaterials and the chondrogenesis in various types of porous scaffolds. The cell ingrowth into the porous scaffolds is modulated by initial cell loading efficiency. Therefore, well-interconnected pore structure and even pore distribution of the scaffolds are essential for efficient cell seeding. According to our previous work, well-interconnected macroporous scaffolds can be prepared by gas-foaming/salt-leaching method using ammonium bicarbonate salt as porogen additives. In this work, primary chondrocytes were cultured in PLGA 65/35 scaffolds fabricated by using our method. Cells seeded in the scaffolds showed well distribution by agitated seeding method. Histochemical staining of proteoglycans present in the scaffolds was used to visualize the chondrocyte ingrowth in the scaffolds. At 3 weeks, the population of chondrocytes was increased for the most part of the scaffolds, and extra cellular matrix (ECM) secretion was increased as culture periods progressed.

• 한국공작기계학회논문집
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• 제12권4호
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• pp.63-69
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• 2003

In discontinuous composite mechanics, shear lag theory is one of the most popular model because of its simplicity and accuracy. However, it does not provide sufficiently accurate strengthening predictions in elastic regime then the fiber aspect ratio is small. This is due to its neglect of stress transfer across the fiber ends and the stress concentrations that exist in the matrix regions near the fiber ends. To overcome this shortcoming, a more simplified shear lag model introducing the stress concentration factor which is a function of several variables, such as the modulus ratio, the fiber volume fraction, the fiber aspect ratio, is proposed. It is found that the modulus ratio($E_f$/$E_m$) is the essential variable among them. Thus, the stress concentration factor is expressed as a function of modulus ratio in the derivation. It is found that the proposed model gives a good agreement with finite element results and has the capability to correctly predict the values of interfacial shear stresses and local stress variations in the small fiber aspect ratio regime.

• 대한조선학회논문집
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• 제34권2호
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• pp.20-26
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• 1997

6분력계를 (Fx=Fy=Fz=10Kg, Mx=My=Mz=1Kg-m) 설계하고 제작하여 검증시험을 실시하였다. 설계된 검력계는 순수 굽힘모오먼트를 받는 보를 적절히 배치하는 형식의 일체형 6분력계로, 스트레인 게이지와 휘스턴회로를 이용한 것이다. 개발된 검력계의 정밀 검정시험을 통하여 특성을 파악하고 힘의 성분간에 간섭을 계산된 영향계수를 이용하여 분리하였다. 반복된 검정시험을 통하여 개발된 검력계의 정확도와 신뢰도를 확인할 수 있었으며, 축적된 경험은 앞으로의 실용적이고 신뢰도 높은 각종 검력계의 설계 및 제작에 도움을 줄 수 있을것으로 믿어진다.

• 대한수의학회지
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• 제55권2호
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• pp.125-131
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• 2015

A total of 11,395 animals were impounded in shelters in Seoul in 2013. The Animal Protection Division of the Seoul metropolitan government has annual contracts with local veterinary associations as well as Korean animal rescue and management organizations for providing shelter to animals, and collects monthly statistics from these groups. In 2013, the collected intake and outcome data for 25 districts were reviewed to analyze shelter capacity in terms of housing capacity (monthly daily average intake, required holding capacity, and adoption-driven capacity), staff capacity (staff hours required for daily care), and live release rate. Seasonal variations in the monthly daily average intake were observed, indicating that management of these shelters requires various strategies. This study was performed to analyze and interpret meaningful statistics for improving the efficiency of animal shelters in Seoul. However, inconsistent collection of animal statistics limited data compilation. Creation of a basic animal statistics matrix with reference to well-designed matrices from recognized professional animal shelters is essential. These complied statistical data will help plan for future animal shelter needs in Seoul.

• Smart Structures and Systems
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• 제3권4호
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• pp.455-474
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• 2007

A flexibility-based distributed computing strategy (DCS) for structural health monitoring (SHM) has recently been proposed which is suitable for implementation on a network of densely distributed smart sensors. This approach uses a hierarchical strategy in which adjacent smart sensors are grouped together to form sensor communities. A flexibility-based damage detection method is employed to evaluate the condition of the local elements within the communities by utilizing only locally measured information. The damage detection results in these communities are then communicated with the surrounding communities and sent back to a central station. Structural health monitoring can be done without relying on central data acquisition and processing. The main purpose of this paper is to experimentally verify this flexibility-based DCS approach using wired sensors; such verification is essential prior to implementation on a smart sensor platform. The damage locating vector method that forms foundation of the DCS approach is briefly reviewed, followed by an overview of the DCS approach. This flexibility-based approach is then experimentally verified employing a 5.6 m long three-dimensional truss structure. To simulate damage in the structure, the original truss members are replaced by ones with a reduced cross section. Both single and multiple damage scenarios are studied. Experimental results show that the DCS approach can successfully detect the damage at local elements using only locally measured information.

• Applied Science and Convergence Technology
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• 제23권6호
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• pp.351-356
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• 2014

The electronic structure at organic-organic interface gives essential information on device performance such as charge transport and mobility. Especially, the molecular orientation of organic material can affect the electronic structure at interface and ultimately the device performance in organic photovoltaics. The molecular orientation is examined by the change in ionization potential (IP) for metal phthalocyanines (MPc, M=Zn, Cu)/fullerene ($C_{60}$) interfaces on ITO by adding the CuI templating layer through ultraviolet photoelectron spectroscopy measurement. On CuPc/$C_{60}$ bilayer, the addition of CuI templating layer represents the noticeable change in IP, while it hardly affects the electronic structure of ZnPc/$C_{60}$ bilayer. The CuPc molecules on CuI represent relatively lying down orientation with intermolecular ${\pi}-{\pi}$ overlap being aligned in vertical direction. Consequently, in organic photovoltaics consisting of CuPc and $C_{60}$ as donor and acceptor, respectively, the carrier transport along the direction is enhanced by the insertion of CuI templaing layer. In addition, optical absorption in CuPc molecules is increased due to aligned transition matrix elements. Overall the lying down orientation of CuPc on CuI will improve photovoltaic efficiency.