• Journal of the Microelectronics and Packaging Society
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• v.8 no.3
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• pp.37-42
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• 2001

The concerns of the toxicity and health hazard of lead in solders have demanded the research to find suitable lead-free solder alloys. It was discussed that effect of the intermetallic formation and structure on the reliability of solder joints. In this study, lead-free solder alloys with compositions of Sn/3.5Ag/0.75Cu, Sn/2.0Ag/0.5Cu/2.0Bi were applied to the 48 $\mu$BGA packages. Also, the lead-free solder alloys compared with eutectic Sn/37Pb solder using shear test under various aging temperature. Common $\mu$BGA with solder components was aged at $130^{\circ}C$, $150^{\circ}C$ and $170^{\circ}C$. And the each temperature applied to 300, 600 and 900 hours. The thickness of the intermetallics was measured for each condition and the activation energy for their growth was computed. The fracture surfaces were analyzed using SEM (Scanning Electron Microscope) with EDS (Energy Dispersive Spectroscopy). These results for reliability of lead-free interconnections are discussed.

• Food Science of Animal Resources
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• v.22 no.2
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• pp.122-129
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• 2002

This study was conducted to investigate the effect of dietary Panax ginseng Leaves, (PGL), Dioscorea japonica Hulls(DJH) and Oriental Medicine Refuse(OMR) on meat quality and physico-chemical properties in meat sample of Korean Native Chicken(KNC). KNC were randomly assigned to one of the 4 dietary treatment : 1) control(commercial feed), 2) PGL(commercial feed supplemented with 5% Panax ginseng leaves) 3) DJH(commercial feed with 5% Dioscorea japonica hulls) 4) OMR (commercial feed with 5% oriental medicine refuse). They were feed one of the experimental diets for 12 weeks and slaughtered. 160 KNC raised for 20 weeks. In the proximate composition, moisture, crude protein and crude ash was no significantly difference. But fat content were tended to high in control. The heating loss of control, PGL, DJH and OMR were 28.44%, 30.44%, 28.83% and 25.71% and control, PGL, and DJH were higher compared with that of OMR. The WHC(whiter holding capacity) was contrary to heating loss. The shear value and pH did not show any difference among the treatment groups. There were no significantly different in meat color(L*, a*,　b*) between control and treatment groups (L*=63.20∼70.67, a*=2.20∼4.15, b*=2.70∼6.01). In sensory evaluation, juiciness, tenderness and flavor were not detected to panelist. Among fatty acid, oleic acid of DJH and OMR were higher than that of control and PGL(p<0.05). Also, saturated fatty acid/unsaturated fatty acid of control, PGL, DJH and OMR were 1.58, 1.58, 1.64 and 1.67, respectively. DJH and OMR groups was higher than control and PGL groups(p<0.05). Total amino acid contents was control>OMR>DJH>PGL. Major amino acid of KNC was comprised to glutamic acid, lysine, aspartic acid, leucine and arginine.

• Composites Research
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• v.28 no.4
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• pp.232-238
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• 2015

As a new method to predict the degree of dispersion in carbon nanocomposites, the electrical resistance (ER) method has been evaluated. After CNT epoxy resin was dropped on CF tow, the change in electrical resistance of carbon fiber tow was measured to evaluate dispersion condition in CNT epoxy resin. Good dispersion of CNTs in carbon nanocomposite exhibited low change in ER due to wetted resin penetrated on CF tow. However, because CNT network was formed among CFs, non-uniform dispersion occurred due to nanoparticle filtering effect by CF tow. The change in ER for poor dispersion exhibited large ER signal change. The change in ER was used for the dispersion evaluation of CNT epoxy resin. Correlation between interlaminar shear strength (ILSS) and dispersion condition by ER method was established. Good CNT dispersion in nanocomposites led to good interfacial properties of fiberreinforced nanocomposites.

• Composites Research
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• v.33 no.3
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• pp.161-168
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• 2020

In this paper, we have studied the mechanical properties of thermoplastic carbon fiber fabric composites with spread technology and compression molding temperature were investigated. Carbon fiber reinforcement composites were fabricated using commercial carbon fiber fabrics and spread carbon fiber fabrics. Mechanical properties of the commercial carbon fiber composites (CCFC) and spread carbon fiber composites (SCFC) according to compression molding temperatures were investigated. Thermal properties of the polypropylene film were examined by rheometer, differential scanning calorimetry, thermal gravimetric analysis. Tensile, flexural and Inter-laminar shear test. Commercial carbon fiber reinforcement composites and spread carbon fiber composites were fabricated at 200~240℃ above the melting temperature of the polypropylene film. Impregnation properties according to compression molding temperature of the polypropylene film were investigated by scanning electron microscopy. As a result, as the compression molding temperature was increased, the viscosity of the polypropylene film was decreased. The mechanical properties of the compression molding temperature of 230℃ spread carbon fiber composite was superior.

• Journal of the Korea Concrete Institute
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• v.17 no.6 s.90
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• pp.993-1000
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• 2005

Various types of FRP materials have been applied for structural strengthening of RC beams in various forms. When CFRP plates are used, a premature failure used to occur before enough strengthening effect appears. This is primarily due to the rip-off of CFRP Plate attached on RC beams. Despite of numerous studies on the rip-off failure of externally strengthened RC beams, its failure mechanism is not definitely clarified yet. Investigations from literatures have shown that the rip-off failure is dependant on the vertical and shear stresses at the level of main reinforcements in RC beams. This study suggests an analytical model to Investigate the rip-off failure load based on the stress states at the level of main reinforcements. The proposed model is relatively simple and produces very comparable results to the test data. It is believed that the proposed model can be successfully used to provide more information on the rip-off failure mechanisms and its prevention.

• Journal of the Korean Society of Food Science and Nutrition
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• v.37 no.3
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• pp.362-366
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• 2008

This study was carried to investigate effects of gamma irradiation on the moisture, crude protein, crude lipid, 2-thiobarbituric acid (TBA) values, color stability, texture, and sensory properties of restructured pork jerky. Restructured pork jerky was irradiated at dose levels of 0, 3, 5, 7 and 10 kGy with a use Co-60 source. There were no significant differences in the moisture, crude protein, crude lipid contents, and TBA values. However, as doses of gamma irradiation increased, the redness (a-value) of restructure pork jerky increased whereas shear force of restructure pork jerky was decreased by gamma irradiation. Sensory evaluation showed that sensory scores were reduced by gamma irradiation. Therefore, gamma irradiation could be an effective means to improve color and texture of restructured pork jerky, but only with proper consideration for sensory quality.

• Journal of the Korean Geotechnical Society
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• v.21 no.5
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• pp.187-196
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• 2005

Since the allowable bearing capacities of piles in weathered/fractured rock are mainly governed by settlement, the load-displacement behavior of pile should be known accurately. To predict pile head settlement at the design stage, the exact understanding of the load-transfer mechanisms is essential. Therefore, in this research, the load-transfer mechanism of drilled shaft socketed into weathered rock was investigated. For the investigation, five cast-in-place concrete piles with diameters of 1,000 mm were socketed into weathered gneiss. The static axial load tests and the load-transfer measurements were performed to examine the axial resistant behavior of the piles. A comprehensive field/laboratory testing program on weathered rock at the Held test sites was also performed to describe the in situ rock mass conditions quantitatively. And then, the effect of rock mass condition on the load transfer mechanism was investigated. The f-w (side shear resistance-displacement) curve of the pile in moderately weathered rock reached to yielding point at a for millimeter displacements, and after yielding point, the rate of resistance increment dramatically decreased. However, the f-w curve in the highly/completely weathered rock did not show the obvious yielding point, and the resistance gradually increased showing the hyperbolic pattern until relatively high displacement (>15 mm). The q-w (end bearing resistance-displacement) curves showed linear response at least until the base displacement of approximately 10 mm, regardless of rock mass conditions.

• Journal of the Korean Geotechnical Society
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• v.32 no.11
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• pp.5-19
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• 2016

This paper presents the results from three-dimensional finite element (FE) analysis undertaken to provide insight into the lateral behaviors of piled gravity base foundation (GBF) for offshore wind turbine. The piled GBF was originally developed to support the gravity based foundation in very soft clay soil. A GBF is supported by five piles in a cross arrangement to achieve additional vertical bearing capacity. This study considered four different cases including a) single pile, b) three-by-three group pile (with nine piles), c) cross-arrangement group pile (with five piles), and d) piled GBF. All the cases were installed in homogenous soft clay soil with undrained shear strength of 20 kPa. From the numerical results, p-y curves and thus P-multiplier was back-calculated. For the group pile cases, the group effect decreased with increasing the number of piles. Interestingly, for the piled GBF, the P-multipliers showed a unique trend, compared to the group pile cases. This study concluded that the global lateral behaviour of the piled GBF was influenced strongly by the interaction between GBF and contacted soil surface.

• BMB Reports
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• v.41 no.12
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• pp.846-851
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• 2008

This study was conducted to identify marbling-related candidate genes in M. longissimus dorsi of high- and low-marbled Hanwoo. The longissimus dorsi muscles were selected for gene expression from eight Hanwoo steer carcasses based on crude fat content. In the analysis of variance, gene expression of five candidate genes, FABP4, SCD, $PPAR\gamma$, Titin and Nebulin was determined to be significantly different between high- and low-marbled Hanwoo steers (P < 0.0001). The Pik-4 and CaMK II genes were also shown to have a significant effect on crude fat content (P < 0.01). In the analysis of the differential expression between high- and low marbled groups, FABP4 gene expression was approximately 2 times higher in the high marbled group relative to the low marbled group. However, the $PPAR\gamma$ and SCD gene were highly expressed in the low marbled group. In addition, Titin and Nebulin were highly expressed in the low marbled group when placed under relatively high shear force. Finally, the Pik-4 and CaM K II gene also displayed a high expression pattern in the low marbled group.

• Journal of Adhesion and Interface
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• v.7 no.2
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• pp.1-11
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• 2006

Interfacial evaluation of the untreated and treated Jute and Hemp fibers reinforced different matrix polypropylene-maleic anhydride polypropylene copolymer (PP-MAPP) composites were investigated by micromechanical technique and dynamic contact angle measurement. For the statistical tensile strength of Jute and Hemp fibers, bimodal Weibull distribution was fitted better than the unimodal distribution. The acid-base parameter on the interfacial shear strength (IFSS) of the natural fiber composites was characterized by calculating the work adhesion, $W_a$. The effect of alkaline, silane coupling agent on natural fibers were obtained with changing MAPP content in PP-MAPP matrices. Alkaline treated fibers made the surface energy to be higher due to removing the weak boundary layers and thus increasing surface area, whereas surface energy of silane treated Jute and Hemp fibers decreased due to blocked high energy sites. MAPP in the PP-MAPP matrix caused the surface energy to increase due to introduced acid-base sites. Microfailure modes of two natural fiber composites were observed clearly differently due to different tensile strength of natural fibers.