• Journal of the Korean Vacuum Society
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• v.7 no.1
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• pp.59-65
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• 1998

Multi-layer diamond-like carbon (DLC) films were deposited by 13.56 MHz r.f. PACVD method. Multi-layer DLC film was composed of 2.5 $mu extrm{m}$ thick pure DLC filml and 0.2$\mu\textrm{m}$ thick Si incorporated DLC (Si-DLC) film as a surface layer. Tribological behaviors of the multi-layer DLC film were investigated with a ball-on-disk type tribometer in ambient atmosphere using AISI 52100 steel ball. Low friction coefficient (<0.1) period increased with increasing the Si content in the surface Si-DLC film. The wear rate after 44,000 cycles and 158,400 cycles were the $2.5\times10^{-8}\sim1.8\times10^{-7}\textrm{mm}^3$/rev. and $7.1\times10^{-9}\sim1.8\times10^{-8}\textrm{mm}^3$/rev.,respectively. The wear rate of the multi-layer DLC film after 158,400 cycles was about 2 times smaller than that of pure DLC films of 2.7 $\mu\textrm{m}$ thickness. This high wear resistance and low friction coefficient was caused by the formation of Si oxide layer on the wear scar surface, as confirmed by the debris composition analysis. It was further shown that this si oxide debris layer on the wear scar surface is formed again even after removing the debris of the steel ball, which maintain the low friction coefficient between multi-layer DLC films and steel ball.

• Proceedings of the Microbiological Society of Korea Conference
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• 2008.05a
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• pp.23-25
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• 2008

Serum complement proteins comprise an important system that is responsible for several innate and adaptive immune defence mechanisms. There were three well described pathways known to lead to the generation of a C3 convertase, which catalyses the proteolysis of complement component C3, and leads to the formation of C3 opsonins (C3b, iC3b and C3d) that fix to bacteria. A pivotal step in the complement pathway is the assembly of a C3 convertase, which digests the C3 complement component to form microbial-binding C3 fragments recognized by leukocytes. The spleen clears microorganisms from the blood. Individuals lacking this organ are more susceptible to Streptococcus pneumoniae. Innate resistance to S. pneumoniae has previously been shown to involve complement components C3 and C4, however this resistance has only a partial requirement for mediators of these three pathways, such as immunoglobulin, factor B and mannose-binding lectin. Therefore it was likely that spleen and complement system provide resistance against blood-borne S. pneumoniae infection through unknown mechanism. To better understand the mechanisms involved, we studied Specific intracellular adhesion molecule-grabbing nonintegrin (SIGN)-R1. SIGN-R1, is a C-type lectin that is expressed at high levels by spleen marginal-zone macrophages and lymph-node macrophages. SIGN-R1 has previously been shown to be the main receptor for bacterial dextrans, as well as for the capsular pneumococcal polysaccharide (CPS) of S. pneumoniae. We examined the specific role of this receptor in the activation of complement. Using a monoclonal antibody that selectively downregulates SIGN-R1 expression in vivo, we show that in response to S. pneumoniae or CPS, SIGN-R1 mediates the immediate proteolysis of C3 and fixation of C3 opsonins to S. pneumoniae or to marginal-zone macrophages that had taken up CPS. These data indicate that SIGN-R1 is largely responsible for the rapid C3 convertase formation induced by S. pneumoniae in the spleen of mice. Also, we found that SIGN-R1 directly binds C1q and that C3 fixation by SIGN-R1 requires C1q and C4 but not factor B or immunoglobulin. Traditionally C3 convertase can be formed by the classical C1q- and immunoglobulin-dependent pathway, the alternative factor-B-dependent pathway and the soluble mannose-binding lectin pathway. Furthermore Conditional SIGN-R1 knockout mice developed deficits in C3 catabolism when given S. pneumoniae or its capsular polysaccharide intravenously. There were marked reductions in proteolysis of serum C3, deposition of C3 on organisms within SIGN-$R1^+$ spleen macrophages, and formation of C3 ligands. The transmembrane lectin SIGN-R1 therefore contributes to innate resistance by an unusual C3 activation pathway. We propose that in the SIGN-R1 mediated complement activation pathway, after binding to polysaccharide, SIGN-R1 captures C1q. SIGN-R1 can then, in association with several other complement proteins including C4, lead to the formation of a C3 convertase and fixation of C3. Therefore, this new pathway for C3 fixation by SIGN-R1, which is unusual as it is a classical C1q-dependent pathway that does not require immuno globulin, contributes to innate immune resistance to certain encapsulated microorganisms.

• Journal of Embryo Transfer
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• v.6 no.2
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• pp.1-17
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• 1991

It is widely recognized that the embryonic or fetal loss after breeding is common in the cattle and that it is an important factor affecting reproductive efficiency. The causes of this loss have been subject of extensive researches and the results indicate that the embryonic mortality may he primary factor responsible for low pregnancy rates in non-embryo transfer bovine populations as well as embryo transfer programs. However, it's causes are still not clearly understood. The embryonic mortality or pregnancy rate has been influenced by various embryonic and maternal effects related to genetic and environmental factors. The timing and extent of embryonic mortality vanes greatly according to authors and estimating methods, because it is difficult to make direct measurements. The major important factors that may influence the embryonic losses or pregnancy rates after embryo transfer can be summeirized. 1.When an embryo is transferred to unmated recipients, the contralateral transfer to corpus luteum results in a lower survival rate than ipsilateral deposition. When the embryos are transferred for the production of twin calves, their survivals and twin pregnancies have quite inconsistent according to the transfer methods either to the unmated-synchronized or already mated recipients and more works are needed to accurrately clarify the previous results. 2.Although embryos can be cultured in vitro some hours without the great declines in pregnancy rates, the rates differ markedly among culture times and media but may be improved by co-transfer systems. 3.Embryo developmental stages and quality grades clearly affect the survival rate following freezing and the pregnancy rate after transfer and the selection of embryos without chromosome abnormalities and of high fertile semen may also be considered to increase the pregnancy rates. 4.Many researches have attempted to relate the plasma progesterone levels to pregnancy rates and others have done either direct progesterone supplementation or luteal stimulation by hCG treatment in order to increase the pregnancy rates. However, these effects on pregnancy rates are inconsistent and also contradictory. 5.The asynchrony between donors or embryos and recipients may he a major cause of embryo death and low pregnancy rate and the sensitivity to uterine asynchyony differs in according to the quality and stages of embryos. 6.The extremes of poor or over nutrition during early pregnancy in the recipients are detrimental to the survival of embryos and the good body condition is required to prevent a reduejion of pregnancy rates. The uterine pathogens in embryonic mortality or fertility have been questioned but the infection of C.pyogenes and Campylobacter fetus is still important pathogens. 7.The heat stress during early pregnancy may reduce conceptus weight and possibly increase the embryonic mortality.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2018.06a
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• pp.142.2-142.2
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• 2018

One-dimensional metal oxide nanostructures have attracted considerable research activities owing to their strong application potential as components for nanosize electronic or optoelectronic devices utilizing superior optical and electrical properties. In which, semiconducting $SnO_2$ material with wide-bandgap Eg = 3.6 eV at room temperature, is one of the attractive candidates for optoelectronic devices operating at room temperature [1, 2], gas sensor [3, 4], and transparent conducting electrodes [5]. The synthesis and gas sensing properties of semiconducting $SnO_2$ nanomaterials have become one of important research issues since the first synthesis of SnO2 nanowires. In this study, $SnO_2$ nanowire networks were synthesized on a basis of a two-step process. In step 1, Sn spheres (30-800 nm in diameter) embedded in $SiO_2$ on a Si substrate was synthesized by a chemical vapor deposition method at $700^{\circ}C$. In step 2, using the source of these Sn spheres, $SnO_2$ nanowire (20-40 nm in diameter; $1-10{\mu}m$ in length) networks on a spherical Sn surface were synthesized by a thermal oxidation method at $800^{\circ}C$. The Au layers were pre-deposited on the surface of Sn spherical and subsequently oxidized Sn surface of Sn spherical formed SnO2 nanowires networks. Field emission scanning electron microscopy and high-resolution transmission electron microscopy images indicated that $SnO_2$ nanowires are single crystalline. In addition, the $SnO_2$ nanowire is also a tetragonal rutile, with the preferred growth directions along [100] and a lattice spacing of 0.237 nm. Subsequently, the $NO_2$ sensing properties of the $SnO_2$ network nanowires sensor at an operating temperature of $50-250^{\circ}C$ were examined, and showed a reversible response to $NO_2$ at various $NO_2$ concentrations. Finally, details of the growth mechanism and formation of Sn spheres and $SnO_2$ nanowire networks are also discussed.

• Korean Chemical Engineering Research
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• v.46 no.6
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• pp.1100-1106
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• 2008

In this study, we presented rapid and simple fabrication method of functionalized surface on various substrates as a universal platform for the selective immobilization of cells. The functionalized surface was achieved by using deposition of polyelectrolyte such as poly(allyamine hydrochloride) (PAH), poly(diallyldimethyl ammonium chloride) (PDAC), poly(4-ammonium styrene sulfonic acid) (PSS), poly(acrylic acid) (PAA) and fabrication of poly(ethylene glycol) (PEG) microstructure through micro-molding in capillaries (MIMIC) technique on each glass, poly(methyl methacrylate) (PMMA), polystyrene (PS) and poly(dimethyl siloxane) (PDMS) substrate. The polyelectrolyte multilayer provides adhesion force via strong electrostatic attraction between cell and surface. On the other hand, PEG microstructures also lead to prevent non-specific binding of cells because of physical and biological barrier. The characteristic of each modified surface was examined by using static contact angle measurement. The modified surface onto several substrates provides appropriate environment for cellular adhesion, which is essential technology for cell patterning with high yield and viability in the micropatterning technology. The proposed method is reproducible, convenient and rapid. In addition, the fabrication process is environmentally friendly process due to the no use of harsh solvent. It can be applied to the fabrication of biological sensor, biomolecules patterning, microelectronics devices, screening system, and study of cell-surface interaction.

• Korean Journal of Optics and Photonics
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• v.15 no.5
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• pp.469-474
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• 2004

We have fabricated and designed wavelength-tunable sampled grating distributed Bragg reflector laser diodes(SGDBR-LD) by using, for the first time, planar buried heterostructures(PBH). The diodes have low threshold current values and high-performance of laser operation. Growth condition using metal organic chemical vapor deposition(MOCVD) was optimized for the formation of a good butt-coupling at the interface. A maximum output power of the fabricated device was 20 mW under 200 mA continuous wave(CW) operation at $25^{\circ}C$. Average threshold current and voltage were 12 mA and 0.8 V, approximately. This output power is higher than those of ridge waveguide(RWG) and buried ridge stripe(BRS) structures by amounts of 9 mW and 13 mW, respectively. We obtained a tuning range of 44.4nm which is well matched with the target value of our design. The side mode suppression ratio of more than 35 dB was obtained for the whole tuning range. Optical output power variation was less than 5 dB, which is 4 dB smaller than that of RWG structures.

• Journal of Ginseng Research
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• v.44 no.4
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• pp.664-671
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• 2020

Background: Ginsenoside compound-Mc1 (Mc1) is a member of the deglycosylated ginsenosides obtained from ginseng extract. Although several ginsenosides have a cardioprotective effect, this has not been demonstrated in ginsenoside Mc1. Methods: We treated H9c2 cells with hydrogen peroxide (H₂O₂) and ginsenoside Mc1 to evaluate the antioxidant effects of Mc1. The levels of antioxidant molecules, catalase, and superoxide dismutase 2 (SOD2) were measured, and cell viability was determined using the Bcl2-associated X protein (Bax):B-cell lymphoma-extra large ratio, a cytotoxicity assay, and flow cytometry. We generated mice with high-fat diet (HFD)-induced obesity using ginsenoside Mc1 and assessed their heart tissues to evaluate the antioxidant effect and the fibrosis-reducing capability of ginsenoside Mc1. Results: Ginsenoside Mc1 significantly increased the level of phosphorylated AMP-activated protein kinase (AMPK) in the H9c2 cells. The expression levels of catalase and SOD2 increased significantly after treatment with ginsenoside Mc1, resulting in a decrease in the production of H₂O₂-mediated reactive oxygen species. Treatment with ginsenoside Mc1 also significantly reduced the H₂O₂-mediated elevation of the Bax:Bcl2 ratio and the number of DNA-damaged cells, which was significantly attenuated by treatment with an AMPK inhibitor. Consistent with the in vitro data, ginsenoside Mc1 upregulated the levels of catalase and SOD2 and decreased the Bax:B-cell lymphoma-extra large ratio and caspase-3 activity in the heart tissues of HFD-induced obese mice, resulting in reduced collagen deposition. Conclusion: Ginsenoside Mc1 decreases oxidative stress and increases cell viability in H9c2 cells and the heart tissue isolated from HFD-fed mice via an AMPK-dependent mechanism, suggesting its potential as a novel therapeutic agent for oxidative stress-related cardiac diseases.

• The Journal of the Petrological Society of Korea
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• v.6 no.2
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• pp.111-122
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• 1997

Provenance type and paleoclimate of the Jinju and Iljig formation were studied on the basis of compositions of sandstones from the western Euiseong area in the northern part of Kyong-sang basin. The average compositions of quartz, feldspar and lithic grain(Q:F:L) from the sandstones are 53:40:7 and 50:46:4 for Jinju and Iljig formations, respectively. The values fall into the arkosic arenite field. Petrographic detrital modes of the sandstones mainly suggest transitional continental block for the tectonic setting of the provenance. All sandstones from the Jinju and IIjig formations show chemical compositions close to average values of arkose(Pettijohn, 1975). $Na_2O$ contents is relatively high. $Fe_2O_3$(total iron) and MgO contents decrease with increasing $SiO_2$ contents since the framework grains of arkoses supposed to be derived from granitic rocks are poor in ferromagnesian minerals. The detrital framework grains still possess climatic signs even though the grains were more or less altered during deep burial. Bivariant plot of Suttner and Dutta(1986) suggests semi-arid to semi-humid paleoclimate during the deposition of the Jinju and Iljig sandstones.

• The Journal of the Petrological Society of Korea
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• v.23 no.4
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• pp.311-324
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• 2014

The Hongjeom formation of the Pyeongan Supergroup in the Munkyeong coalfield mainly consists of metapsammite and metapelites. Metampelites occur as slate preserving chloritoid+chlorite+muscovite and andalusite+biotite+chlorite+muscovite mineral assemblages. Chloritoid and andalusite occur as porphyroblast, and the matrix composed of fine-grained micas. Metamorphic P-T conditions for these mineral assemblages are $510-520^{\circ}C$ and 3.0-3.5kbar based on P-T pseudosection in $MnO-K_2O-FeO-MgO-Al_2O_3-SiO_2-H_2O(MnKFMASH)$ system and isopleth intersections of Fe/(Fe+Mg) ratios in chloritoid and chlorite. The medium temperature and low pressure metamorphism resulted from a higher geothermal gradient ($40-45^{\circ}C/km$) condition than that of burial metamorphism. The youngest (SHRIMP U-Pb age; ca. 327-310 Ma) detrital zircon grains from the Hongjeom formation display oscillatory zoning and relatively high Th/U ratio (0.60-1.12). Based on the previous sedimentary, paleontological, and geochronological studies in the Taebaeksan basin together with results of this study, we suggest that (1) initial deposition of the Hongjeom formation was contemporaneous with a magmatic activity in the provenance, (2) the Pyeongan Supergroup was deposited in an arc-related basin at an active continental margin during the Carboniferous to Permain, and (3) magmatic activities occurred repetitively in relatively short interval in the active continental margin had continuously supplied sediments to the basin.

• Journal of the Korean Magnetics Society
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• v.19 no.4
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• pp.121-125
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• 2009

Amorphous $Ge_1$_$_xMn_x$ semiconductor thin films grown by low temperature vapor deposition were annealed at various temperatures from 400 to $700^{\circ}C$ for 3 minutes in high vaccum chamber. The electrical and magnetotransport properties of as-grown and annealed samples have been studied. X-ray diffraction patterns analysis revealed that the samples still maintain amorphous state after annealling at $500^{\circ}C$ for 3 minutes and they were crystallized when annealing temperature increase to $600^{\circ}C$. Temperature dependence of resistivity measurement implied that as-grown and annealed $Ge_1$_$_xMn_x$ films have semiconductor characteristics, the increase of resistivity with annealling temperature was obseved. The $700^{\circ}C$-annealed sample exhibited negative magnetoresistance (MR) at low temperatures and the MR ratio was ${\sim}$8.5% at 10 K. The asymmetry was present in all MR curves. The anomalous Hall Effect was also observed at 250 K.