• Journal of the Korean Ceramic Society
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• v.38 no.1
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• pp.15-21
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• 2001

전자파 차폐 및 반사방지용으로 사용되는 SiO$_2$/ITO 이층박막의 전기적 특성에 미치는 전이금속이온의 영향에 대해 고찰하고 전자파 차폐이론식으로부터 박막의 전도특성에 모사하여 효과적인 전자파 차폐효과를 얻기 위한 전도막을 설계하고자 하였다. ITO 상층부에 전이금속염을 첨가한 실리카 복합졸을 코팅하여 SiO$_2$/ITO 이층막을 제조한 결과 최저 표면저항치를 나타내는 첨가량은 전이금속의 종류에 따라 차이를 보이지만 Sn 및 Zn이 첨가된 졸로부터 형성된 박막은 $10^{5}$Ω/$\square$ 이하의 낮은 저항치를 보였으며 가장 안정된 표면저하을 나타내었다. 또한 전자파 차폐효과와 전도박막의 표면저항을 차폐이론식으로부터 모사한 결과 Zn과 Sn의 전이금속염이 첨가된 SiO$_2$/ITO 투명전도막은 TCO99에서 정한 전자파 차폐기준에 부합하였다.다.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2004.10a
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• pp.218-221
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• 2004

Dry sliding wear behavior of electro-pressure sintered Co, $Co-20\;wt.\%$ CuSn and $Co-20\;wt.\%$ WC composites were investigated. Wear tests of the materials were carried out using a pin-on-disk wear tester at various loads of 10N-100N under a constant sliding speed condition of 0.38m/s against glass ($83\%\;SiO_2$) beads. Sliding distances were varied with a range of $100m{\sim}600m$. A scanning electron microscopy was used to examine morphologies of worn surfaces, cross-sections, and wear debris. The $Co-20\;wt.\%$ WC composite had the highest and the $Co-20\;wt.\%$ CuSn composite showed the lowest wear resistance among the tested materials. All specimens exhibited low friction coefficients ranging from 0.12 to 0.4 at the applied load of 100N.

• Journal of Conservation Science
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• v.17 s.17
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• pp.33-38
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• 2005

One piece of Haedong-Tongue(해동통보) minted at 1,102 A.D. was excavated from No.20 wooden coffin, Sinbong-dong, Cheongju. It was analyzed by micro-XRF and ICP and determined the concentrations of ten elements such as Cu, Pb, Sn, Zn, Fe, Mn, Sb, Co, As, Ag and Ni. The measurement of lead isotope ratios was also carried out in order to predict the provenance of raw materials used for minting of Haedong-Tongbo. It was found that Haedong-Tongbo was minted with three compositions of $Cu\;75.5\%,\;Pb\;13.3\%\;and\;Sn\;6.0\%$, which were different from the typical composition of Chosen-Tongbo and Sangpyung-Tongbo used in Chosen dynasty. Lead isotope ratios of Haedong-Tongbo showed that the provenance of lead used for minting of it suggested the possibility to be originated from Southern part of Korea.

• Clinical and Experimental Reproductive Medicine
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• v.38 no.1
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• pp.24-30
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• 2011

Objective: The objectives of this study were to analyze efficacy of immature and mature mouse oocytes after vitrification and warming by applying various combinations of cryoprotectants (CPAs) and/or super-rapid cooling using slush nitrogen ($SN_2$). Methods: Four-week old ICR female mice were superovulated for GV- and MII-stage oocytes. Experimental groups were divided into two groups. Ethylene glycol (EG) only group: pre-equilibrated with 1.5 M EG for 2.5 minutes and then equilibrated with 5.5 M EG and 1.0 M sucrose for 20 seconds. EG+dimethylsulfoxide (DMSO) group: pre-equilibrated with 1.3 M EG+1.1 M DMSO for 2.5 minutes and equilibrated with 2.7 M EG+2.1 M DMSO+0.5 M sucrose for 20 seconds. The oocytes were loaded onto grids and plunged into $SN_2$or liquid nitrogen ($LN_2$). Stored oocytes were warmed by a five-step method, and then their survival, maturation, cleavage, and developmental rates were observed. Results: The EG only and EG+DMSO groups showed no significant difference in survival of immature oocytes vitrified after warming. However, maturation and cleavage rates after conventional insemination were greater in the EG only group than in the EG+DMSO group. In mature oocytes, survival, cleavage, and blastocyst formation rates after warming showed no significant difference when EG only or EG+DMSO was applied. Furthermore, cleavage and blastocyst formation rates of MII oocytes vitrified using $SN_2$ were increased in both the EG only and EG+DMSO groups. Conclusion: A combination of CPAs in oocyte cryopreservation could be formulated according to the oocyte stage. In addition, $SN_2$ may improve the efficiency of vitrification by reducing cryoinjury.

• Journal of the Korean Society of Food Science and Nutrition
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• v.38 no.4
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• pp.479-485
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• 2009

The acidolysis was performed to produce structured lipid with palm mid fraction (PMF) and stearic acid for 7, 24, and 36 hr at $70^{\circ}C$. The reaction was catalyzed by lipozyme TLIM (immobilized lipase from Thermonyces lanuginosa, amount of 10% and 20% by weight of total substrates) in the shaking water bath. The reaction conditions for maximum incorporation of stearic acid on the structured lipid were obtained when molar ratio of PMF and stearic acid was 1:2; concentration of lipozyme TLIM was 20wt%; reaction temperature was $70^{\circ}C$; and reaction time was 36 hr. After reaction under this condition, incorporation of stearic acid in the structured lipid was obtained up to 36.3% while the major components of triacylglycerol were 1,2-dipalmitoyl-3-stearoylglycerol (PPS, 28.19 area%), 1-palmitoyl-2-oleoyl-3-stearoylglycerol (POS/PSO, 20.70 area%) and 1-palmitoyl-2,3-distearoylglycerol (PSS, 18.13 area%). However, the fatty acid composition at the sn-2 position suggested that the positional specificity of lipozyme TLIM was not observed due to the acyl migration.

• The Bulletin of The Korean Astronomical Society
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• v.39 no.2
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• pp.38-38
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• 2014

Despite the great success that stellar evolution theory have enjoyed during the last 50 years, new challenges are emerging with recent observations of supernovae: many aspects of supernovae cannot be easily explained by the standard scenarios on supernova progenitors. A few examples include the red supergiant problem - the dearth of Type IIP supernova progenitors with masses higher than about 16 Msun, the non-detection of Type Ib/c supernova progenitors despite very deep searches in pre-supernova optical images, the unexpected blue colors of some Type IIn supernova progenitors, and the exotic stellar explosions of both ultra-faint and super-luminous types that have been only recently discovered. By confronting these observations with new stellar evolution models, we are making significnt progress in better understanding the role of metallicity, rotation and binary interactions for the pre-supernova evolution of massive stars. In this talk, I will give a brief review on the recent observational constraints on supernova progenitors and a progress report on several research projects that deal with pair-instability supernovae from the local Universe, type Ib/c supernovae from massive binary systems, and some peculiar stellar explosions like SN2012Z.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2008.11a
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• pp.38-38
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• 2008

질화갈륨계 발광다이오드는 차세대 반도체 조명용 및 기타 광전소자 등에의 응용 가능성 때문에 주목을 받고 있다. 본 발표에서는 발광다이오드용 In/ITO 전극이 p-형 질화갈륨과 열처리 후 오믹접촉을 이루는 메커니즘을 설명한다.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.1
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• pp.45-50
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• 2014

A vibration test coupon is prepared with nine plastic ball grid array packages on a printed circuit board using SnPb solders, and a random vibration test is conducted on the coupon. Life data from the test are analyzed, and it is shown that over the board, life data is location-dependent. For investigating this location dependency, a finite element model is developed and the equivalent stresses, which are defined based on the stress response functions at each node, are investigated. It is shown that one of the corner solder balls has the maximum equivalent stress at a package during the test. Finally, it is demonstrated that the maximum equivalent stress and durability life are inversely proportional.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38B no.10
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• pp.801-807
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• 2013

WSN consists of hundreds to thousands of sensor nodes. In order to solve the problem of energy consumption imbalance cluster head is reelected in every round, while node authentication scheme is utilized for secure communication. However, re-clustering increases the overhead of sensor nodes and during the node authentication phase the frequent AREQ/AREP message exchange also increases the overhead. Therefore, a secure and energy efficient protocol, by which overhead of sensor nodes is reduced and long time communication is achieved, is required for wireless sensor network. In this paper, an energy efficient and reliable IDE-LEACH protocol for WSN is proposed. The proposed protocol is prolongs networks lifetime about average 20% compared to the LEACH-based protocols and all attending nodes in communication form BS authentication consisted of trusted nodes.

• The Korea Journal of Herbology
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• v.27 no.6
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• pp.55-61
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• 2012

Objectives : Allium Hookeri (AH) is a traditional herb to treat inflammatory diseases in India and Myanmar. Recently, AH cultivation was succeeded in South Korea. This study was performed to evaluate the anti-inflammatory effects of Korean AH in RAW264.7 cells, mouse macrophage cell line. Methods : To evaluate the anti-inflammatory effects of root of AH, we prepared the 70% ethanol extract, then we examined the productions of nitrite, and pro-inflammatory cytokines. To examine the nitrite, and cytokines, the RAW264.7 cells were treated with AH, then stimulated with lipopolysaccharide (LPS, 500 ng/ml) for 24 h. Then the cells were harvested for griess assay, ELISA and real-time reverse transcription polymerase chain reaction (RT-PCR). Also to detect the ability of AH to induce heme oxygenase-1 (HO-1), we examined the HO-1 expression using real time RT-PCR and western blot. Furthermore, we examined the mitogen activated-protein kinases (MAPKs) and nuclear factor kappa B (NF-${\kappa}B$) activation to find out the underlying mechanisms. Results : AH ethanol extract significantly inhibited the productions of nitrite and interleukin (IL)-$1{\beta}$. AH treatment increased the HO-1 expression dramatically at 1 h, then peaked at 3 h. When the HO-1 was inhibited by tin (Sn) protoporphryin-IX (SnPP), the anti-inflammatory action of AH was reversed. AH treatment inhibited the activation of p38, but not extracelluar signal-regulated kinase (ERK 1/2) and c-Jun $NH_2$-terminal kinase (JNK) and also the degradation of inhibitory kappa B a (Ik-$B{\alpha}$) in the LPS-stimulated RAW 264.7 cells. Conclusions : These data could suggest that AH exerts anti-inflammatory influences through up-regulation of HO-1 and deactivation of p38.