• Journal of the Korean Society for Precision Engineering
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• v.28 no.5
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• pp.623-631
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• 2011

Metallic sandwich panels based on a truss core structure have been developed for a wide range of potential applications with their lightweight and multi-functionality. Structural performance of sandwich panels can be predicted from the studies on mechanical behavior of a unit cell of truss core structures. Analytical investigations on the unit cell provide approximated guidelines for the design of overall core structures for a specific application in short time. In this study, the effects of geometrical parameters on mechanical behavior of a pyramidal shape of unit cell were investigated with analytical models. The unit cell with truss member angle of 45 degree was considered as reference model and other models were designed to have the same weight and projected area but different truss member angle. All truss members were assumed to be connected with pin joint in analytical models. Under the assumptions, the equivalent strength and stiffness of the unit cell under compressive and shear loads were predicted and compared. And finally, the optimum core member angle to have maximum mechanical property could be calculated and verified with FE analysis results.

• Tribology and Lubricants
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• v.5 no.1
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• pp.44-50
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• 1989

High strength steel is similar to carbon steel in its composition. This material is developed originally for special uses such as aerospace and automobile due to its high strength and shock-free property in spite of lightness. But the chemical attraction of high strength steel is serious, which includes comminution of formation, metalization and strengthening. Machining results in built-up edge between this material and the tool. Especially the work hardening behavior results in tool life shortening, which was caused by temperature generation during machining. In this study, cooling system was made in which liquid nitrogen is supplied to circulate in order to make up for these weaknesses. Machining of high strength steels, which is recognized as difficult to machine materials, was conducted after tool is cooled at -195$\circ$C. Experimental results showed that the tool was cooled down rapidly below -195$\circ$C in about 200 seconds. The tool temperature of machining with cooling system was lowered by 60~95$\circ$C than that of machining in room temperature. The hardness of the surface of chip is decreased by machining with cooling system. And the machining using the cooling system made it possible to increase shear angle, to retain smooth surface on chip without built-up-edge and to get a better roughness.

• Food Science of Animal Resources
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• v.30 no.6
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• pp.930-937
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• 2010

This study was carried out to investigate the textural and sensory properties of pork jerky with differently added sources of tenderizer or humectant at final concentrations of 2 or 5% (v/w). Pork jerky treated with 5% glycerol, kiwi, or pineapple had lower moisture content and water activity than that of control pork jerky (p<0.05). The addition of tenderizer or humectant resulted in a lower shear force than that of control (p<0.05). The addition of 2 or 5% glycerol resulted in higher equilibrium moisture content (EMC) than other treatments, and addition of tenderizer or humectant produced a higher EMC than that of control (p<0.05). Furthermore, addition of pineapple and kiwi to the samples affected the structures of the myosin heavy chain and the actin filaments of myofibrillar protein, respectively. Trained panel sensory evaluations indicated that pineapple enhanced the flavor score, whereas tenderness score was improved by the addition of tenderizer or humectant (p<0.05).

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.4
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• pp.2407-2414
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• 2015

This paper presents analytical expressions for the determination of out of plane thermo-elastic properties for conventional laminated composite plates. The approach follows that commonly accepted for in-plane properties. Results over a variety of lay-ups reveals that it is poor assumption to use transverse tape lamina properties to represent out of plane laminate properties for laminates with more than 10% plies oriented off-axis($90^{\circ}$) from uniaxial or for laminates with angle plies of $15^{\circ}$ or greater.

• Textile Coloration and Finishing
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• v.21 no.4
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• pp.1-10
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• 2009

This paper surveys the physical properties of sheath/core nylon/PET high hollow composites filaments and its fabrics according to the various elution conditions such as concentration of elution, eluted time and eluted temperature. For this purpose, sheath/core nylon/PET filament was texturized and four kinds of fabric specimens were woven with different warp and weft densities. These grey fabrics were eluted with two kinds of concentrations of NaOH (30g/l, 40g/l), three kinds of eluted temperatures $50^{\circ}C,\;60^{\circ}C,\;85^{\circ}C$) and two kinds of eluted times (60min, l20min). The elution characteristics of these specimens were investigated and discussed with different elution conditions. In addition, the mechanical properties such as extensibility, bending rigidity, shear modulus and compressional work of these specimens aceording to the elution conditions were analysed and summarized with cross-sectional shapes of eluted filaments measured by SEM.

• Food Science and Biotechnology
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• v.18 no.5
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• pp.1138-1144
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• 2009

This study was carried out to investigate the cooking properties and lipid oxidation stability during storage at $4{\pm}1^{\circ}C$ when the various levels (5 to 20%) of doenjang (Korean fermented soybean paste) were added to pork patties cooked by pan frying (PF) and convection oven (CO). With increasing the addition of doenjang, cooking properties of pork patties revealed the improved cooking yield, less diameter reduction, and less thickness increase. Also, the shear force, hardness, and chewiness of pork patties were reduced. The PF cooking method showed better cooking properties than CO. Lipid oxidation expressed by the thiobarbituric acid reactive substances (TBARS) values was significantly reduced by the addition of more than 5% doenjang (p<0.05). The TBARS values of cooked pork patties by PF were significantly lower than CO during the 8 days of the storage (p<0.05). The development of warmed-over flavor (WOF) in cooked pork patties was delayed as the amount of the doenjang was increased. It was suggested that the addition of doenjang and PF favorably affected the cooking properties and stability of lipid oxidation in pork patties.

• Journal of Fashion Business
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• v.22 no.2
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• pp.107-117
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• 2018

Nettle fiber, a sustainable fiber, was applied to the fabrication of denim to identify changes in textile appearance and formation. For the weaving of nettle denim, nine specimens, distinguished by three kinds of composite use of nettle fiber and three stages of fabrication processes, were used. The kinetic characteristics of the nine specimens were measured by the KES-FB system, and the images of the specimens of finished denim textiles, captured with a CCD Camera, were analyzed. In terms of the extensibility (EM) of nettle denim, all specimens showed post-processing increase, thereby suggesting an easy transformation of the textile as a source material for denim fabric. The effects of washing on the woven formation of denim were also identified. The geometric roughness (SMD), the problematic property of bast-fiber-like nettle fiber, was found to be decreased by washing. In terms of the bending rigidity (B) of the textile, the post-processing shrinking percentage of elastic nettle denim was found to decrease; all specimens that underwent bio-washing only also manifested that post-processing elasticity increased. To improve the draping of nettle denim, a mixed spinning together with washing were found to be advantageous. In terms of the shear stiffness (G), which is closely associated with the appearance of clothes, the formation of textile was improved regardless of the types of processing, including bio-washing and bleach washing.

• Journal of the Korean Geotechnical Society
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• v.20 no.3
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• pp.67-74
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• 2004

A case study was performed to verify the applicability of existing formulae for predicting bridge scour in cases where its piers are founded in fine-grained soils. The object of study was the Kanghwa Choji Bridge area where the streambed consists of mainly clayey soil. Site investigation included: direct measurement of scour depths around piers using an ultrasonic probe; and collection of undisturbed soil samples which were later used to determine geotechnical properties and scour rate under different stream velocities. Scour depth prediction was made by employing several conventional methods and compared with the measured value. All methods, not taking soil's intrinsic property against erosion into consideration, overestimated scour depth by a factor of 3.6 to 6.5. On the other hand, the SRICOS method yielded a reasonably acceptable overestimation by a factor of 1.7.

• Journal of Biomedical Engineering Research
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• v.41 no.1
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• pp.14-21
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• 2020

Recently, porous additive manufactured(AM) cages have been introduced to provide more desirable stiffness and may be beneficial to bone ingrowth. They are designed to attempt to reduce the subsidence problem of traditional titanium cage and to get osseointegrative property that PEEK doesn't have. This study was performed to evaluate the mechanical performance of newly developed lumbar porous AM cages. Three types of mechanical tests were performed in accordance with the ASTM standards: Static compression, compression-shear, and subsidence tests. The porous AM cages with 60% porosity showed similar device stiffness and strength as the various products submitted to FDA 510(k), and their wider contact area improved the subsidence test results by about 50%. In conclusion, the porous AM cages developed in this study were considered mechanically safe and could be an alternative to solid PEEK cages.

• Coupled systems mechanics
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• v.9 no.2
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• pp.125-145
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• 2020

In this paper, we present a 3D thermo-hydro-mechanical coupled discrete beam lattice model of structure built of the nonisothermal saturated poro-plastic medium subjected to mechanical loads and nonstationary heat transfer conditions. The proposed model is based on Voronoi cell representation of the domain with cohesive links represented as inelastic Timoshenko beam finite elements enhanced with additional kinematics in terms of embedded strong discontinuities in axial and both transverse directions. The enhanced Timoshenko beam finite element is capable of modeling crack formation in mode I, mode II and mode III. Mode I relates to crack opening, mode II relates to in-plane crack sliding, and mode III relates to the out-of-plane shear sliding. The pore fluid flow and heat flow in the proposed model are governed by Darcy's law and Fourier's law for heat conduction, respectively. The pore pressure field and temperature field are approximated with linear tetrahedral finite elements. By exploiting nodal point quadrature rule for numerical integration on tetrahedral finite elements and duality property between Voronoi diagram and Delaunay tetrahedralization, the numerical implementation of the coupling results with additional pore pressure and temperature degrees of freedom placed at each node of a Timoshenko beam finite element. The results of several numerical simulations are presented and discussed.