• Journal of the Korean Society for Precision Engineering
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• v.13 no.11
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• pp.124-131
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• 1996

The dynamic material property of Mn-B ally high-strength steel is investigated through the rod impact test which is one of simple test methods for the analysis of the material behavior under high-strain-rate. Rod impact test is performed to produce the deformed shape of rod and analyzed by the one-dimensional theory based on conservation law and the two-dimensional hydrocode AUTODYN-2D. The dynamic yield stress is determined and compared with the static yield stress to investigate the strain-rate sensitivity of Mn-B alloy high-strength steel.

• Advances in Traditional Medicine
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• v.7 no.2
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• pp.128-132
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• 2007

Diarun plus, a polyherbal formulation containing herbal ingredients of folkloric Antidiabetic effect, was investigated for its effect on glycemic status in rats and mice. In contrast to conventional chemical induced diabetic animal models, changes in glycemic states were induced by physiological maneuvers. Results revealed that in euglycemic animals Diarun plus elicited little change (-10 to +10%), which was insignificant. In food deprivation/swim exercise induced hypoglycemia, Diarun plus reduced the degree of hypoglycemia in both rats and mice (from 38% to 27% in rats and 45% to 32% in mice). Similarly, the marked hyperglycemia induced by dextrose (70% in rats and 95% in mice) was reduced markedly to 8% and 25% respectively. The findings of the present study suggests that the ingredients of Diarun plus have the unique property of maintaining near euglycemic state irrespective of the altered glycemic state, and that have no significant effect in euglycemic condition.

• Progress in Superconductivity and Cryogenics
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• v.26 no.2
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• pp.19-23
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• 2024

3D printing has the advantage of being able to process various types of parts by layering materials. In addition to these advantages, 3D printing technology allows models to be processed quickly without any special work that can be used in different fields to produce workpieces for various purposes and shapes. This paper deals to not only increase the utilization of 3D printing technology, but also to revitalize 3D printing technology in applications that require similar cryogenic environments. The goal of this study is to identify the mechanical properties of polylactic acid and photopolymer resin processed by Fused Deposition Modeling (FDM) and Digital Light Processing (DLP) respectively. The entire process is meticulously examined, starting from getting the thermal contraction using an extensometer. A uniaxial tensile test is employed, which enables to obtain the mechanical properties of the samples at both room temperature (RT) and cryogenic temperature of 77 K. As the results, photopolymer resin exhibited higher tensile properties than polylactic acid at RT. However, at cryogenic temperatures (77 K), the photopolymer resin became brittle and failure occurred due to thermal contraction, while polylactic acid demonstrated superior tensile properties. Therefore, polylactic acid is more suitable for lower temperatures.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.4
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• pp.813-818
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• 2015

In this paper, WiMedia Distributed-MAC protocol is adopted for development of a seamless N-screen wireless service. Furthermore, to provide the OSMU (One Source Multi Use) N-screen service through P2P streaming in the seamless D-MAC protocol, a new Multicast-free DRP Availability IE is proposed and analyzed. In this Multicast-free DRP Availability IE, indicating Multicast DRP Owner and Receiver is required. The ACK frame transmissions are not required for Multicast transmissions in P2P N-screen services. Using this property, the Multicast-free DRP Availability IE scheme is proposed to expand the number of time slots available for unicast and multicast DRP reservations. Simulation results show that our Multicast scheme enhances performances in vewpoints of DRP reservation conflict and throughput.

• Natural Product Sciences
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• v.17 no.4
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• pp.279-284
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• 2011

Phytochemical studies on the whole extract of Sedum hybridum L., a Mongolian medicinal plant, has been undertaken to isolate active principles responsible for its anti-oxidative and antibacterial activities. Eighteen known compounds, i.e. (1) quercetin, (2) kaempferol, (3) herbacetin-8-O-${\beta}$-D-xylopyranoside, (4) myricetin, (5) gossypetin-8-O-${\beta}$-D-xylopyranoside, (6) gallic acid, (7) 2,4,6-tri-O-galloyl-D-glucopyranose, (8) 6-O-galloylarbutin, (9) myricetin-3-O-${\alpha}$-L-arabinofuranoside, (10) quercetin-3-O-${\alpha}$-L-arabinofuranoside, (11) caffeic acid, (12) ethylgallate, (13) (-) epigallocatechin-3-O-gallate, (14) palmitic acid, (15) stearic acid, (16) stearic acid ethyl ether, (17) ${\beta}$-sitosterol and (18) ${\beta}$-sitosteryl-O-${\beta}$-D-glucopyranose have been isolated and their molecular structures identified by spectroscopic analysis. Thirteen substances including seven flavonol components (1, 2, 3, 4, 5, 9 and 10), five gallic acid derivatives (6, 7, 8, 12 and 13) and caffeic acid (11) exhibited significant, dose-dependent, DPPH radical scavenging activity. Galloyl esters 12 and 13 were revealed to be main active principles for the antibacterial property of the extract of Sedum hybridum L.

• Proceedings of the KIEE Conference
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• 2001.07c
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• pp.1540-1542
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• 2001

In this paper, the amount of additives in the electrode were investigated the relation of the mechanical properties and surface luminance of copper foil. Especially, organic compound of PEG(Poly-ethylene Glycol) was added from 1 to 20ppm for the propose of increasing the mechanical property and the surface state. The surface luminance of copper foil is appealed 69.25 at 2ppm-15A/$dm^2$ and 68.25 at 2ppm-10A/$dm^2$. It guess that 10ppm-10A/$dm^2$ occurred pin-hole. Tensile strength was not showed the significant difference but elongation appealed the most value at 5ppm-15A. We earned that the most PEG value of mechanical properties is 5 PPM.

• Tribology and Lubricants
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• v.25 no.1
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• pp.20-24
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• 2009

TiC-derived carbon coatings have been synthesized at $600^{\circ}C$ temperature treatment with $H_2/Cl_2$ mixture gases. From Raman spectroscopy measurements, the modified layer was covered with carbon and the thick-ness of the layer was increased with increasing reaction time. And $I_D/I_G$ ratio was decreased with increasing reaction time. The superior tribological property was obtained from TiC reacted with $Cl_2$ gas for 2 hrs. And the tribological property measurements indicate that TiC-derived carbon layer has $0.9{\times}10_{-6}mm^3/Nm$ in wear coefficient and 0.13 in friction coefficient.

• Korean Journal of Mathematics
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• v.22 no.1
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• pp.29-36
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• 2014

The limiting diffusion of special diploid model can be defined as a discrete generator for the rescaled Markov chain. Choi([2]) defined the operator of projection $S_t$ on limiting diffusion and new measure $dQ=S_tdP$. and showed the martingale property on this operator and measure. Let $P_{\rho}$ be the unique solution of the martingale problem for $\mathcal{L}_0$ starting at ${\rho}$ and ${\pi}_1,{\pi}_2,{\cdots},{\pi}_n$ the projection of $E^n$ on $x_1,x_2,{\cdots},x_n$. In this note we define $$dQ_{\rho}=S_tdP_{\rho}$$ and show that $Q_{\rho}$ solves the martingale problem for $\mathcal{L}_{\pi}$ starting at ${\rho}$.

• Honam Mathematical Journal
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• v.38 no.3
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• pp.507-552
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• 2016

For a complex number q and a divisor function ${\sigma}_1(n)$ we define $$C(q):=q{\prod_{n=1}^{\infty}}(1-q^n)^{16}(1-q^{2n})^4,\\D(q):=q^2{\prod_{n=1}^{\infty}}(1-q^n)^8(1-q^{2n})^4(1-q^{4n})^8,\\L(q):=1-24{\sum_{n=1}^{\infty}}{\sigma}_1(n)q^n$$ moreover we obtain the number of representations of $n{\in}{\mathbb{N}}$ as sum of 24 squares, which are possible for us to deduce $L(q^4)C(q)$ and $L(q^4)D(q)$.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.21 no.2
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• pp.333-339
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• 1996

In this paper, an effiicent quatization method of line spectrum pairs(LSP) with cascaded structure of vector quantizer and scalar quantizer is proposed. First, input LSP parameters is vector-quantized using a codebook with a moderate number of entries. In the second stage of quantization, the components of residual vector are individution improve the quantizer by the scalar quantizer. The utilization of ordering property and the inclusion of interframe prediction improve the quantizer performance and remove the stability check routine. The new vector-scalar cascaded quantizer using 27 bits/frame shows a transparent quality that an average specytural distortion is 1 dB and the frame proportion with above 2 dB spectral distion is less than 2%.