• Korean Journal of Medicinal Crop Science
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• v.19 no.4
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• pp.287-299
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• 2011

Pharmacological effects of Panax ginseng have been demonstrated in cardiovascular system, endocrine secretion and immune system, together with antitumor, anti-stress and anti-oxidant activities. Modern scientific data show protective effect of ginseng against bone marrow cell death, increased survival rate of experimental animals, recovery of hematopoietic injury, immunopotentiation, reduction of damaged intestinal epithelial cells, inhibition of mutagenesis and effective protection against testicular damages, caused by radiation exposure. And also, ginseng acts in indirect fashion to protect radical processes by inhibition of initiation of free radical processes and thus reduces the radiation damages. The research has made much progress, but still insufficient to fully uncover the action mechanism of ginseng components on the molecule level. This review provides the usefulness of natural product, showing no toxic effects, as an radioprotective agent. Furthermore, the further clinical trials on radioprotection of ginseng need to be highly done to clarify its scientific application. The effective components of ginseng has been known as ginsenosides. Considering that each of these ginsenosides has pharmacological effect, it seems likely that non-saponin components might have radioprotective effects superior to those of ginsenosides, suggesting its active ingredients to be non-saponin series. These results also show that the combined effects of saponin and non-saponin components play an important role in the radioprotective effects of ginseng.

• Journal of the Korea Concrete Institute
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• v.14 no.1
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• pp.76-82
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• 2002

The rapid-set cement concrete causes high hydration temperature and nay result in a high drying shrinkage and shrinkage-induced cracking. This problem may be fixed by incorporating polypropylene fibers in rapid-set cement concrete, because of increased toughness, resistance to impact, corrosion, fatigue, and durability. A series of concrete drving shrinkage tests was peformed in order to investigate the shrinkage properties of polypropylene fiber reinforced concrete with experimental variables such as concrete types, fiber reinforcement, W/C ratio, with and without restraint. Uni-axially restrained bar specimens were used for the restrained shrinkage tests. The results were as follows; The dry shrinkage of rapid-set cement concrete was much lessor than that oi OPC, probably because of smaller weight reduction rate by early hydration and strength development. The constraint and bridging effects caused by polypropylene fibers were great for the rapid-setting cement concrete when compared with that of plain concrete, and this resulted In increased resistance against tensile stress and cracking.

• International Journal of Fluid Machinery and Systems
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• v.9 no.4
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• pp.370-381
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• 2016

As a single-channel pump is used for wastewater treatment, this particular pump type can prevent performance reduction or damage caused by foreign substances. However, the design methods for single-channel pumps are different and more difficult than those for general pumps. In this study, a design optimization method to improve the hydrodynamic performance of a single-channel pump impeller is implemented. Numerical analysis was carried out by solving three-dimensional steady-state incompressible Reynolds-averaged Navier-Stokes equations using the shear stress transport turbulence model. As a state-of-the-art impeller design method, two design variables related to controlling the internal cross-sectional flow area of a single-channel pump impeller were selected for optimization. Efficiency was used as the objective function and was numerically assessed at twelve design points selected by Latin hypercube sampling in the design space. An optimization process based on a radial basis neural network model was conducted systematically, and the performance of the optimum model was finally evaluated through an experimental test. Consequently, the optimum model showed improved performance compared with the base model, and the unstable flow components previously observed in the base model were suppressed remarkably well.

• Journal of the Microelectronics and Packaging Society
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• v.6 no.2
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• pp.13-21
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• 1999

Flip chip assembly directly on organic boards offers miniaturization of package size as well as reduction in interconnection distances resulting in a high performance and cost-competitive Packaging method. This paper describes the investigation of alternative low cost flip-chip mounting processes using electroless Ni/Au bump and anisotropic conductive adhesives/films as an interconnection material on organic boards such as FR-4. As bumps for flip chip, electroless Ni/Au plating was performed and characterized in mechanical and metallurgical point of view. Effect of annealing on Ni bump characteristics informed that the formation of crystalline nickel with $Ni_3$P precipitation above $300^{\circ}C$ causes an increase of hardness and an increase of the intrinsic stress resulting in a reliability limitation. As an interconnection material, modified ACFs composed of nickel conductive fillers for electrical conductor and non-conductive inorganic fillers for modification of film properties such as coefficient of thermal expansion(CTE) and tensile strength were formulated for improved electrical and mechanical properties of ACF interconnection. The thermal fatigue life of ACA/F flip chip on organic board limited by the thermal expansion mismatch between the chip and the board could be increased by a modified ACA/F. Three ACF materials with different CTE values were prepared and bonded between Si chip and FR-4 board for the thermal strain measurement using moire interferometry. The thermal strain of ACF interconnection layer induced by temperature excursion of $80^{\circ}C$ was decreased with decreasing CTEs of ACF materials.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.50 no.12
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• pp.639-647
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• 2001

We present an integrated optical microswitch, composed of silicon waveguides, gold-coaled silicon micromirrors, and electrostatic contact actuators, for applications to the optical signal transceivers. For a low switching voltage, we modify the conventional curled electrode microactuator into a electrostatic microactuator with touch-down beams. We fabricate the silicon waveguides and the electrostatically actuated micromirrors using the ICP etching process of SOI wafers. We observe the single mode wave propagation through the silicon waveguide with the measured micromirror loss of $4.18\pm0.25dB$. We analyze major source of the micromirror loss, thereby presenting guidelines for low-loss micromirror designs. From the fabricated microswitch, we measure the switching voltage of 31.74V at the resonant frequency of 6.89kHz. Compared to the conventional microactuator, the present contact microactuator achieves 77.4% reduction of the switching voltage. We also discuss a feasible method to reduce the switching voltage to 10V level by using the electrode insulation layers having the residual stress less than 30MPa.

• The Transactions of the Korean Institute of Power Electronics
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• v.13 no.1
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• pp.70-77
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• 2008

Conventional PDP power system, which commonly uses two isolation transformer, consists of sustaining power ($V_S$), addressing power($V_A$), and Multi power($V_M$). Because each of these power conversion circuits use transformer and control IC, there are several defects: decrease of efficiency, rise of cost, and parts stress. This paper is proposed the method which operates PDP power system only with one transformer. The proposed method contributes not only to high-efficient performance of the DC/DC power stage and improvement of reliability but also to reduction of cost by reducing volume and size. Also, proposed method is proper to Address Display-period Separation(ADS) which is one of the driving methods of PDP. Superiority of the proposed method is proved by comparison with conventional method and theoretical, experimental analysis.

• The Transactions of the Korean Institute of Power Electronics
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• v.22 no.6
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• pp.551-554
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• 2017

This paper proposes a three-level LLC resonant converter using integrated magnetics (IM). Given that the switch voltage stress of the proposed converter is guaranteed to be half of the input voltage, the switching losses can be greatly reduced, thereby benefitting the high-frequency operation. To reduce the volume of reactive components such as transformers, high-frequency driving and planar core are applied. However, two resonant inductors and one transformer are required because of the three-level structure and the limited leakage inductance of the planar transformer for the resonant operation. Therefore, the effect of volume reduction is not very large. In order to solve these drawbacks, this paper proposes a new IM that integrates all magnetic elements used in the proposed three-level resonant converter by using the magnetizing inductor as a resonant inductor. The experimental results are presented by conducting a theoretical analysis of a prototype with 350 W to 800 kHz.

• Journal of the Korean Recycled Construction Resources Institute
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• v.8 no.2
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• pp.175-182
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• 2020

The application of epoxy coated reinforcements is increased as a means to prevent a corrosion of reinforcements embedded in reinforced concrete structures, However, epoxy coating may reduce the bond capacity between concrete and reinforcement, which results a longer development length and lap splice length. This paper aims to the possibility of modification in lap splice length from reduction of basic development length which was confirmed using a direct pull out test. Total 36 beam specimens were tested to compare the lap splice properties of normal and epoxy coated reinforcements with beam-end test for various lap lengths and diameters of reinforcements. According to the results on failure modes, deformations, and crack widths of this experiments, the modification factor of 1.2 should be used, though the direct bond capacity is assured through direct pull out test.

• Journal of Pharmacopuncture
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• v.18 no.2
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• pp.86-87
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• 2015

Objectives: Condurango is widely used in various systems of complementary and alternative medicine (CAM) against oesophageal and stomach ailments including certain types of cancer. However, until now no systematic study has been conducted to verify its efficacy and dose with proper experimental support. Therefore, we examined if ethanolic extract of Condurango could ameliorate benzo[a]pyrene (BaP)-induced lung cancer in rats in vivo to validate its use as a traditional medicine. Methods: After one month of scheduled BaP feeding (50 mg/kg body-weight), lung cancer developed after four months. BaP-intoxicated rats were then treated with Condurango (0.06 mL) twice daily starting at the end of the four months for an additional one, two and three months, respectively. Effects of Condurango were evaluated by analyzing lung histology, reactive oxygen species (ROS) and antioxidant biomarkers, DNA-fragmentation, RT-PCR (Reverese Transcriptase-Polymerase Chain Reaction), ELISA (Enzyme linked immunosorbent assay) and western blot of several apoptotic signalling markers and comparing the results against those obtained for controls. Results: A histological study revealed gradual progress in lung tissue-repair activity in Condurango-fed cancer-bearing rats, showing gradual tissue recovery after three months of drug administration. Condurango has the capacity to generate ROS, which may contribute to a reduction in anti-oxidative activity and to an induction of oxidative stress-mediated cancer-cell death. Condurango-activated pro-apoptotic genes (Bax, caspase-3, caspase-9, p53, cytochrome-c, apaf-1, ICAD and PARP) and down-regulated antiapoptotic-Bcl-2 expression were noted both at mRNA and protein levels. Studies on caspase-3 activation and PARP cleavage by western blot analysis revealed that Condurango induced apoptosis through a caspase-3-dependent pathway. Conclusions: The anticancer efficacy of an ethanolic extract of Condurango for treating BaP-induced lung cancer in rats lends support for its use in various traditional systems of medicine.

• Journal of Pharmaceutical Investigation
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• v.32 no.1
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• pp.13-19
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• 2002

Water-lipid soluble multivitamin formulations were widely used to reduce the disease and stress of animals as husbandry has made a remarkable progress in recent. But the efficiency of these formulations is far from satisfactory. So, this study was attempted to develop the physically and chemically stable and useful multivitamin o/w emulsion. Multivitamin o/w emulsion composed of water, soybean oil (10%, v/v), vitamin A, D, E, K, $B_2,\;B_6,\;B_{12}$ and panthenol. To make a stable o/w emulsion, the egg lecithin (2%, w/v) and glycerin (2.5%, w/v) were used for emulsifier and thickening agent, respectively. The oil in water emulsion system was manufactured by microfluidizer and the physicochemical stability of this emulsion was evaluated. The average particle size and interfacial tension were measured. From the result of interfacial tension tested, critical micelle concentration of the egg lecithin was 0.5% (w/v) and optimal concentration for the preparation of emulsion was 2% (w/v). The mean particle size was about $0.6\;{\mu}m$ which was suitable for injections. Short-term accelerated stability as physical stability study was tested by centrifuging and freeze-thawing the emulsion samples. The additions of vitamins resulted in the increment of particle size and reduction of physical stability of emulsion. But it is not an enormous problem for the stability of emulsion. Also, we have performed the long-period preservation stability test for the vitamins. All vitamins were analysed by HPLC. The result of storage under $4^{\circ}C$ and dark conditions demonstrated that all vitamins were maintained stable at least 16 weeks, except for vitamin $B_{12}$.