• Journal of the Korean Society of Hazard Mitigation
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• v.3 no.2 s.9
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• pp.99-110
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• 2003

In this study, lightening material weight and normalizing structure of preventing system of landslide soil-rock in trench excavation was tried with focusing in safety construction availability and workability. In other words, risk estimate, safety management method investigation, applicability of bracing material and mechanical stability of bracing structure was studied. From these result, structural stability and structural analysis of light weight bracing structure was carried out with common structural analysis program, for examining movement mechanism of bracing structure and normalization of standard. The result are summarized as following. (1) Mechanical ability of bracing members and soil pressure parameter acting to member for ensuring mechanical propriety of bracing structural and useful of new material considering soil mechanics boundary were proposed. Also theory and method of analysis of bracing structural were proposed. (2) As a result of the structure analysis of geographical profile for light pannel used FRP as hard clay mechanical characteristics(bending moment, shear force, axial force) of panel were changed according to groundwater level and it is proved that the result of mechanical analysis is within allowable stress. Thus, light pannel is available for bracing structure in trench excavation.

• Korean Journal of Food Science and Technology
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• v.33 no.2
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• pp.161-165
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• 2001

The dietary fiber was extracted from apple pomace with various concentrations of acidic, alkaline solvents and water in $24.4{\sim}29.3%$ yield. The extractions of water-soluble dietary fiber with acidic(6.85%) and alkaline solvent(6.55%) were more effective than the water extraction(6.0%). The higher extraction yield was obtained with increased concentration of acidic or alkaline solvents. The content of galacturonic acid was higher in the order, 0.01 M HCl(77.5%)>0.05 M HCl(76.8%)>$H_2O(76.1%)$>0.05 M NaOH(73.8%)> 0.01 M NaOH(69.0%) and the extraction with acidic solvent showed the highest pectin yield. The color value increased by extraction with solvent in higher concentration. And at equal concentration, the color value of alkaline extract was higher than that of acidic exctract. There was no relationship between the color value and the extraction yield of dietary fiber. In the investigation on the rheological properties, the shear stress increased in proportion to galacturonic acid contents. While water-soluble dietary fiber extracted with acid and water represented Newtonian rheological properties, the alkaline extract was inclined to have converting property from pseudoplastic to Bingham pseudoplastic with increment of alkaline concentration. In the studies on the time-dependence of apparent viscosity, the thixotropic property with hysteresis loop was observed in alkaline extract.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.44 no.1
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• pp.73-79
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• 2018

The primary cilium protrudes from the cell body like a bio-antenna that has many receptors, channels and signaling molecules to sense and response to external stimuli. The external environment such as ultraviolet irradiation, temperature, humidity, gravity and shear stress always influences skin. Skin responds to external stimuli and differentiates by making melanin, collagen and horny layer. Ciliogenesis participates in developmental processes of skin, such as keratinocyte differentiation and hair formation. And it was reported that skin pigmentation was inhibited when ciliogenesis was induced by sonic hedgehog-smoothened-GLI2 signaling. When skin is exposed to ultraviolet irradiation, alpha-melanocyte stimulating hormones (${\alpha}$-MSH) increase melanin synthesis through activation of the cAMP pathway in melanocytes. We observed that ${\alpha}$-MSH and cAMP production inducers inhibited ciliogenesis of melanocytes. Therefore, we thought that regulation of ciliogenesis is potential candidate target for the development of agents to treat undesirable hyperpigmentation of skin. As a result, we found out that an ethanol extract of Glycyrrhiza glabra (EGG) root and 3,4,5-trimethoxy cinnamate thymol ester (TCTE, Melasolv) significantly inhibit melanin synthesis of normal human melanocyte by inducing primary cilium formation. This study proposed new theory to regulate skin pigmentation and cosmetic components for skin whitening.

• Journal of the Earthquake Engineering Society of Korea
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• v.13 no.1
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• pp.35-43
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• 2009

Two types of piloti-type high-rise RC building structures having irregularity in the lower two stories were selected as prototypes, and nonlinear time history analysis was performed using OpenSees to verify the analysis technique and to investigate the seismic capacity of those buildings. One of the buildings studied had a symmetrical moment-resisting frame (BF), while the other had an infilled shear wall in only one of the exterior frames (ESW). A fiber model, consisting of concrete and reinforcing bar represented from the stress-strain relationship, was adapted and used to simulate the nonlinearity of members, and MVLEM (Multi Vertical Linear Element Model) was used to simulate the behavior of the wall. The analytical results simulate the behavior of piloti-type high-rise RC building structures well, including the stiffness and yield force of piloti stories, the rocking behavior of the upper structure and the variation of the axial stiffness of the column due to variation in loading condition. However, MVLEM has a limitation in simulating the abrupt increasing lateral stiffness of a wall, due to the torsional mode behavior of the building. The design force obtained from a nonlinear time history analysis was shown to be about $20{\sim}30%$ smaller than that obtained in the experiment. For this reason, further research is required to match the analytical results with real structures, in order to use nonlinear time history analysis in designing a piloti-type high-rise RC building.

• 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.15 no.2
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• pp.119-127
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• 1986

The rheological properties of mayonnaise were studied with cylindrindrical viscometer. It was observed that mayonnaise showed pseudoplastic behavior, yield stress and time dependent characteristics. In the initial period of shear time, the decay of viscosity of mayonnaise was followed by a second-order kinetic equation. The influence of temperature on viscosity could be described by Arrhenius equation. The apparent viscosity of mayonnaise markedly increased with an rise in the concentration of egg yolk; and the emulsion was most stable at the concentration of 12%. At the concentration of $65{\sim}75%$ oil, the apparent viscosity was increased; the maximum value was reached at 75% oil, and above 75% oil, the remarkable decreased was observed. The size of oil drops was decreased with an increase in oil concentration of 75% oil. The apparent viscosity of mayonnaise was increased with an rise in water contents, while being decreased with one in the concentration of vinegar.

• Journal of the Korean Geotechnical Society
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• v.32 no.11
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• pp.43-50
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• 2016

A reinforcement is required to ensure the structural safety in case of railway embankment excavation under railway load. A large diameter soil nailing with concrete wall is applied as the reinforcement method instead of the conventional soil nailing system. In this study, a series of 3 dimensional numerical analyses are performed to investigate the optimum reinforcement considering 15 different conditions based on the length, lateral spacing, diameter, and inclination of the reinforcement. The interface between soil nail and perimetric grout is considered by means of cohesion, stiffness and perimeter of the grout. 0.3 m of reinforcement diameter is assessed as the most appropriate based on the economical viewpoint though ground displacement decreases with the increase of diameter, however the difference of displacement is negligible between 0.4 m and 0.3 m of diameter. Surface settlement, lateral displacement of wall, and stress of reinforcement are calculated and economic viewpoint to reinforce embankment considered. Consequently, the optimum reinforcement conditions considering those factors are evaluated as 3 m in length, 0.3 m in diameter, 1.5 m in lateral spacing, and 10 degree of inclination angle in the case of 3 m of excavation depth. Additionally, inclined potential failure surface occurs with approximately 60 degrees from the end of nails and the surface settlement and wall lateral displacement are restrained successfully by the large diameter soil nailing, based on the result of shear strain rate.

• KSBB Journal
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• v.22 no.2
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• pp.91-96
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• 2007

The saccharogenic liquid (SFW) obtained by the enzymatic saccharification of food wastes was used as a medium for production of bacterial cellulose (BC). The enzymatic saccharification of food wastes was carried out by the cultivation supernatant of Tricoderma inhamatum KSJ1 culture. Acetobacter xylinum KJ1 was employed for the BC production culture. Under the scaled-up aeration condition of 1.0 vvm, 5.64 g/L of BC was produced in 3 days cultivation in 50 L air circulation bioreactor using SFW medium with addition of 0.4% agar. The productivity was similar to that of 10 L air circulation bioreactor (5.84 g/L). This cultivation method with 50 L air circulation bioreactor decreasing shear stress and increasing oxygen transfer coefficient ($k_La$) was very useful in BC mass production. The physical properties, such as morphology, molecular weight, crystallinity, and tensile strength of BC produced by the static culture (A), the air circulation culture using 10 L bioreactor (B) and 50 L bioreactor (C) were investigated. The number average molecular weight of BCs produced under the different culture conditions (A-C) showed 2,578,000, 1,975,000, and 1,809,000, respectively. Tensile strength was 1.72 $kg/mm^2$, 1.19 $kg/mm^2$, and 1.18 $kg/mm^2$, respectively. All of the BCs had a form of cellulose I representing pure cellulose. The relative degree of crystallinity showed the range of 86.2$\sim$87.8%. BC production by the air circulation culture mode brought more favorable results in terms of the physical properties and its ease of scale-up. Therefore, it is expected that the new BC production method, the air circulation culture using SFW, would contribute greatly to BC-related manufacturing.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.19 no.1 s.71
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• pp.93-103
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• 2006

It is absolutely essential that safety assessment of the containment buildings during service life because containment buildings are last barrier to protect radioactive substance due to the accidents. Therefore, this study describes an enhanced degenerated shell finite element(FE) which has been developed for nonlinear FE analysis of reinforced concrete(RC) containment buildings with elasto-plastic material model. For the purpose of the material nonlinear analysis, Drucker-Prager failure criteria is adapted in compression region and material parameters which determine the shape of the failure envelop are derived from biaxial stress tests. Reissner-Mindlin(RM) assumptions are adopted to develop the degenerated shell FE so that transverse shear deformation effects is considered. However, it is found that there are serious defects such as locking phenomena in RM degenerated shell FE since the stiffness matrix has been overestimated in some situations. Therefore, shell formulation is provided in this paper with emphasis on the terms related to the stiffness matrix based on assumed strain method. Finally, the performance of the present shell element to analysis RC containment buildings is tested and demonstrated with several numerical examples. From the numerical tests, the present results show a good agreement with experimental data or other numerical results.

• Journal of Advanced Marine Engineering and Technology
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• v.38 no.4
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• pp.367-375
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• 2014

In numbers of kinds of heat exchanger, the shell-tube heat exchanger is the most commonly used type of heat exchanger in the industry field. In order to improve the thermal performance of the heat exchanger, this study was analyzed heat transfer characteristics according to arrangement of baffle and direction of baffle and bump phase of baffle about shell-tube heat exchanger using appropriate SST (Shear Stress Transport) turbulence model for flow separation and boundary layer analysis. As the boundary condition for CFD (Computational Fluid Dynamics) analysis, the inlet temperature of shell side was constantly 344 K and the variation of the water flow rate was 6, 12, 18 and 24 l/min. As the result of analysis, zigzag baffle arrangement enhances heat transfer rate and pressure drop. Furthermore, in the direction of the baffle, heat transfer rate is more improved with vertical type and angle $45^{\circ}$ type than existing type, and pressure drop was little difference. Also, the bump shape of baffle surface contributes to heat transfer rate and pressure drop improvement due to the increased heat transfer area. Through analysis results, we knew that the increase of the heat transfer was influenced by flow separation, fluid residual time, contact area with the tube, flow rate, swirl and so on.