• Steel and Composite Structures
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• v.33 no.5
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• pp.717-727
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• 2019

This paper is motivated by the lack of studies in the technical literature concerning to vibration analysis of a single-layered graphene sheet (SLGS) with corner cutout based on the nonlocal elasticity model framework of classical Kirchhoff thin plate. An isogeometric analysis (IGA) based upon non-uniform rational B-spline (NURBS) is employed for approximation of the L-shape SLGS deflection field. Trimming technique is employed to create the cutout in geometry of L-shape plate. The L-shape plate is assumed to be Free (F) in the straight edges of cutout while any arbitrary boundary conditions are applied to the other four straight edges including Simply supported (S), Clamped (C) and Free (F). The Numerical studies are carried out to express the influences of the nonlocal parameter, cutout dimensions, boundary conditions and mode numbers on the variations of the natural frequencies of SLGS. It is precisely shown that these parameters have considerable effects on the free vibration behavior of the system. In addition, numerical results are validated and compared with those achieved using other analysis, where an excellent agreement is found. The effectiveness and the accuracy of the present IGA approach have been demonstrated and it is shown that the IGA is efficient, robust and accurate in terms of nanoplate problems. This study serves as a benchmark for assessing the validity of numerical methods used to analyze the single-layered graphene sheet with corner cutout.

• Journal of the Korean institute of surface engineering
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• v.44 no.5
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• pp.226-231
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• 2011

Graphene was coated on STS 316L by electro spray coating method to improve its properties of corrosion resistance and contact resistance. Exfoliated graphite (graphene) was made of the graphite by chemical treatment. Graphene is distributed using dispersing agent, and STS 316L was coated with diffuse graphene solution by electro spray coating method. The structure of the exfoliated graphite was analyzed using XRD and the coating layer of surface was analyzed by using SEM. Analysis showed that multi-layered graphite structure was destroyed and it was transformed into fine layers graphene structure. And the result of SEM analysis on the surface and the cross section, graphene layer was uniformly formed with 3~5 ${\mu}m$ thickness on the surface of substrate. Corrosion resistance test was applied in the corrosive solution which is similar to the PEM fuel cell stack inside. And interfacial contact resistance test was measured to simulate the internal operating conditions of PEM fuel cell stack. The results of measurements show that stainless steel coated with graphene was improved in corrosion resistance and surface contact resistance than stainless steel without graphene coating layer.

• Proceedings of the SAREK Conference
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• 2005.11a
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• pp.317-322
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• 2005

This study is aimed to analyze the effects of heat pipe shape on the heat transfer in solar collector with a axial grooved heat pipe. In the design of a heat pipe. two of the most important criteria to be met are the operating temperature range and the maximum heat transport capacity, When the operating temperature range is known and the working fluid has been selected, the maximum heat transport capacity depends strongly on capillary pressure and liquid flow. The heat transport capacity of the heat pipe will depend on the geometry of the heat pipe, the wick structure. the vapor channel shape. groove number. cooling temperature. condenser length and pipe diameter. So various shapes are used for mathematical models of two-phase flow in grooved heat pipe. From the results. the adequate groove shape and scale are presented by considering the heat transport and capillary limitation.

• Journal of the Society of Disaster Information
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• v.14 no.3
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• pp.379-386
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• 2018

Purpose: This study was to the fragility evaluation of I-shape curved beam structure subjected to strong ground motions including Gyeongju and Pohang earthquakes Method: In particular, to conduct the analytical model, ABAQUS and ANSYS platform was used in this study. Furthermore, the analytical model using 3D Finite Element Model (FEM) was validated, in comparison to the theoretical solutions at the location of 025L, 05L, and 0.75L in static loading condition. In addition, in order to evaluate the seismic fragility of the curved beam structure, 20 seismic ground motions were selected and Monte-Carlo Simulation was used for the empirical fragility evaluation from 0.2g to 1.5g. Result: It was interesting to find that the probability of the system failure was found at 0.2g, as using 190 MPa limit state and the probability of the failure using 390 MPa limit state was starting from 0.6g. Conclusion: This study showed the comparison of the theoretical solution with analytical solution on I-shaped curved beam structures and it was interesting to note that the system subjected to strong ground motions was sensitive to high frequency earthquake. Further, the seismic fragility corresponding to the curved beam shapes must be evaluated.

• Journal of Korean Society of Environmental Engineers
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• v.33 no.6
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• pp.432-438
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• 2011

We need to make the standard of the best baffle shape and L/W ratio of clearwell due to insufficient disinfection in short L/W ratio and uneconomic design in long L/W ratio. The objectives of this research were to evaluate the best shape of baffle and economic L/W ratio in the all sorts of shape and size by using computational fluid dynamics. In the results of this research, the baffle with smaller number of turning flow is more beneficial for hydraulic efficiency. So, even if the same shape and structure, baffle should be designed as smaller number in turning flow. The best shape of baffle is ZigZag type (model 2) and the worst shape is Distributed types (model 4). The ZigZag type can reduce number of baffle about 67% than that of the Distributed types. In the ZigZag type, economic L/W ratio is 30~50. If L/W ratio exceed over 50, it is not economic because construction costs greatly increase and an increasing rate of $T_{10}/T$ is very small.

• Journal of the Korean Society for Precision Engineering
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• v.13 no.3
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• pp.150-157
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• 1996

In this paper, to develop a smart CAD/CAM system for systematically performing from the 3-D solid shape design of products to the CNC cutting operation of products by a machining center, a B-Rep solid modeler is realized based on the half edge data structure. Because the B-Rep solid modeler has the various capabilities related to the solid definition functions such as the creation operation of primitives and the translational and rotational sweep operation, the solid manipulation functions such as the split operation and the Boolean set operation, and the solid inversion function for effectively using the data structure, the 3-D solid shape of products can be easily designed and constructed. Also, besides the automatic generation of CNC code, the B-Rep solid modeler can be used as a powerful tool for realizing the automatic generation of finite elements, the interfer- ence check between solids, the structural design of machine tools and robots and so on.

• Solar Energy
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• v.7 no.2
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• pp.65-73
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• 1987

Microstructural basis for the thermal degradation of electrodeposited black chrome "solar-L-foil" heated in air has been investigated using scanning electron microscopy, energy dispersive x-ray analysis, X-ray diffraction techniques and UV-VIS-NIR spectre-photometer. Experimental result, the change in the shape of the particle comprising the film from their initial needle like structure to a more spherical shape with an oxide after 1hr annealing at $600^{\circ}C$ has been observed. The effect is to degrade solar absorptance of the thin film.

• Proceedings of the Korean Magnetic Resonance Society Conference
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• 2002.08a
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• pp.90-90
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• 2002

Syndecans, transmembrane heparan sulfate proteoglycans, are coreceptors with integrin in cell adhesion process. It forms a ternary signaling complex with protein kinase C and phosphatidylinositol 4,5 bisphosphate (PIP2) for integrin signaling. NMR data indicates that cytoplasmic domain of syndecan-4 (4L) undergoes a conformational transition in the presence of PIP2, forming oligomeric conformation. The structure based on NMR data demonstrated that syndecan-4L itself forms a compact intertwined symmetric dimer with an unusual clamp shape for residues Leu$^{186}$ -Ala$^{195}$ . The molecular surface of the syndecan-4L dimer is highly positively charged. In addition, no inter-subunit NOEs in membrane proximal amino acid resides (Cl region) has been observed, demonstrating that the Cl region is mostly unstructured in syndecan-4L dimmer. However, the complex structure in the presence of PIP2 induced a high order multimeric conformation in solution. In addition, phosphorylation of cytoplasmic domain induces conformational change of syndecan-4, resulting inhibition of PKC signaling. The NMR structural data strongly suggest that PIP2 promotes oligomerization of syndecan-4 cytoplasmic domain for PKC activation and further induces structural reorganization of syndecan for mediating signaling network in cell adhesion procedure.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.54 no.2
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• pp.53-59
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• 2005

In this paper, optimum shape design of permanent magnet in slotted type Permanent Magnet Linear Synchronous Motor(PMLSM) is progressed for minimization of detent force owing to structure of slot-teeth and thrust ripple by harmonic magnetic flux of permanent magnet. In order to reduce remodeling time as changing design parameter for Permanent Magnet shape optimization, the moving model node technique was applied. The characteristics of thrust and detent force computed by finite element analysis are acquired equal effect both skewed basic model and optimum model which is optimization of permanent magnet shape. In addition to, thrust per unit volume is improved 4.l2[%] in optimum model.

• Journal of Korean Ophthalmic Optics Society
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• v.1 no.1
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• pp.15-22
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• 1996

The fine structure of retinal tissue was studied to investigate on effect of Laser irridation on the ICR mouse with electron microscope. The results obtained were as follows: 1. At the normal groups, the most retinal layers were a complex structure, consisting of several specific cells and nerve fiver. 2. In the increasing time of Laser irridation, each cell layer of retina was not uniform of the structure and band. The visual cells were severely heterochromatin swelling of cytoplasm, irregular shape & heterochromatin of nuclear, and disappear of some cytoplasm. The nucleus and nerve fiber of retinal layer was a very irregular shape, formation of vesicle, not identify of each intercellular boundary. The pigment epithelial cells were not an uniform, a large vesicle formation of cytoplasm, and a condensation & very irregular shape of nucleus.