• Archives of Pharmacal Research
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• v.12 no.4
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• pp.249-253
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• 1989

High producers or blocked mutants of aminoglycoside antibiotic-producing Streptomyces spp. were selected by application of an agar plug method and by culturing individual colonies in broth. The productivities of aminoglycoside antibiotic producing organisms were increased by selection of a high producer from colonies obtained by spreading spores of wild strain, or survived from treatment of a mutagen or from the colonies regenerated from protoplast-formation and cell-wall regenerations. Some mutagen treated colonies lost the ability to produce antibiotics (5-8%). Some A-factor negative and deostreptamine or streptidine negative mutants were obtained by N-methyl-N'-nitro-N-nitrosomethylguanidine (MNNG) treatment. Many of the survivors from the MNNG treatment lost the ability to produce antibiotics. Major colonies produced less amount of antibiotics ; only few survived colonies produced more antibiotics than the parent. Resistance of Streptomyces spp. against the antibiotics produced by itself was also markedly affected by mutagen treatment.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.7C
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• pp.666-674
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• 2005

A hybrid multicarrier CDMA/FDM system with a truncated adaptive transmission scheme is analyzed in forward link based on the feedback information from the mobile station. In the single cell environment, the prop(mea scheme outperforms the adaptive FH/DS system as well as the MC DS/CDMA system when orthogonal signature sequences are used. In the multiple cell environment also, the proposed scheme has better performance characteristics than the adaptive FH/DS system when orthogonal and random codes are used as spreading sequences.

• Journal of IKEEE
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• v.25 no.1
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• pp.109-115
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• 2021

In this paper, the fine dust detecting terminal which can transmit data in real time was developed. The terminal used a wide spreading LTE network and was powered by solarcell and battery for easy installation and independent operation, because it did not need the wired power grid or wired communication network. The data showed the possibility of forecasting fine dust changes by analyzing with the data from public meteorologic data. The developed terminal will be helpful for predicting and analyse fine dust's more precise flow and effect on environment with an easy installation on any places.

• The Korea Journal of Herbology
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• v.29 no.6
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• pp.111-116
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• 2014

Objectives : The purpose of this study was to estimate the antioxidant activity of water extract of Cnidii Fructus (CF) and Torilis Fructus (TF) in Leydig cells. Methods : Free radical scavenging activity of CF and TF against 2,2-diphenyl-1-picrylhydrazyl (DPPH) was determined spectrophotometrically. We investigated the effect of CF and TF in Leydig cells by MTT assay. The protective effects of CF and TF against hydrogen peroxide-induced oxidative stress in Leydig cells. Superoxide dismutase (SOD), and catalase activity assays were performed in Leydig cells. Results : The results showed that CF scavenged DPPH radical in a dose-dependent manner by up to 81.2%, TF scavenged DPPH radical in a dose-dependent manner by up to 63.8%. CF showed cell viability as 121.0, 132.7, 126.6% in 5, 10, $100{\mu}g/ml$ concentrations. TF showed cell viability as 127.5, 111.8% in 5, $100{\mu}g/ml$ concentraions, respectively. The hydrogen peroxide-induced cytotoxicity of Leydig cells were protected to 86.3% by CF at concentration of $10{\mu}g/ml$ and protected to 83.5% by TF at concentration of $100{\mu}g/ml$. Both CF and TF at all concentrations, SOD activity was not significantly changed. Catalase activity was significantly increased at 10, $100{\mu}g/ml$ concentrations of CF, respectively. TF's catalase activity showed no significant difference from that of the control. Conclusions : These results suggest that CF, as an antioxidant, protects Leydig cells in hydrogen peroxide-induced oxidative stress. know that "Kwangjebikeup" played a role in settlement and spreading of foreign knowledge to civilians.

• Polymer(Korea)
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• v.24 no.6
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• pp.869-876
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• 2000

In order to improve the cell-compatability of poly(L-lactide-co-glycolide) (75 : 25 by mole ratio of lactide to glycolide, PLGA) surfaces, the physicochemical treatments have been demonstrated. Chemical treatments were 70% perchloric acid. 50% sulfuric acid and 0.5 N sodium hydroxide solution and physical methods were corona and plasma treatment. The water contact angle of surface treated PLGA decreased from 73$^{\circ}$ to 50~60$^{\circ}$, i.e., increased hydrophilicity, due to the introduction of oxygen-containing functional group onto PLGA backbone by the measurement of an electron spectroscopy for chemical analysis. It could be observed that the adhesion and growth of fibroblast cell on physicochemically treated PLGA surfaces, especially perchloric acid treated PLGA surface, were more active than on the controt. In conclusion, it seems that surface wettability as hydrophilicity of PLGA plays an important role in cell adhesion, spreading and growth.

• Macromolecular Research
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• v.17 no.7
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• pp.458-463
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• 2009

Polyurethane (PU) is widely used as a cardiovascular biomaterial due to its good mechanical properties and hemocompatibility, but it is not adhesive to endothelial cells (ECs). Cell adhesive peptides, GRGDS and YIGSR, were found to promote adhesion and spreading of ECs and showed a synergistic effect when both of them were used. In this study, a surface modification was designed to fabricate an EC-active PU surface capable of promoting endothelialization using the peptides and poly(ethylene glycol) (PEG) spacer, The modified PU surfaces were characterized in vitro. The density of the grafted PEG on the PU surface was measured by acid-base back titration to the terminal-free isocyanate groups. The successful immobilization of pep tides was confirmed by amino acid analysis, following hydrolysis, and contact angle measurement. The uniform distribution of peptides on the surface was observed by scanning electron microscopy (SEM) and atomic force microscopy (AFM). To evaluate the EC adhesive property, cell viability test using human umbilical vein EC (HUVEC) was investigated in vitro and enhanced endothelialization was characterized by the introduction of cell adhesive peptides, GRGDS and YIGSR, and PEG spacer. Therefore, GRGDS and YIGSR co-immobilized PU surfaces can be applied to an EC-specific vascular graft with long-term patency by endothelialization.

• Journal of the Korean GEO-environmental Society
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• v.6 no.1
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• pp.33-44
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• 2005

The 'Silt Pond' is 180 hectares in size and contained ultra soft slurry-like soil varying between 3 to 20 meters in thickness. Soil improvement work in the Silt Pond commenced by installing vertical drains in the mid of 1996, following completion of sand spreading up to +4.0m CD. Prior to soil improvement work in the main area of Silt Pond, experimental tests including laboratory tests with a large diameter consolidation cell and pilot tests were carried out to investigate the deformation behavior of an extremely soft soil. Due to its high compressibility, large strain usually occurred in the initial stage of deformation does not comply with Terzaghi's one dimensional consolidation theory. Taking into consideration experimental test results, the soil improvement works were carried out in main area of Silt Pond containing ultra soft soil. This paper presents the case study on improvement of ultra-soft soil.

• Proceedings of the KIEE Conference
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• 1991.07a
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• pp.166-170
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• 1991

An advanced on-resistance model of VDMOS devices in the low voltage regime is proposed and verified by 2-D device simulations. The model considers the lateral gaussian doping profiles in the channel region and exact current spreading angles in the epitaxial layer for both linear and cellular geometries by employing the conformal mapping. It is found out that the on-resistance of low voltage VDMOS may be overestimated considerably if it is analyzed by the conventional method. The 2-D device simulation results show that the proposed model is valid for all ranges of cell spacings and breakdown voltages.

• 한국신재생에너지학회:학술대회논문집
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• 2009.06a
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• pp.111-113
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• 2009

This paper shows that you can achieve high quality N+ emitter layers using a screen printable phosphorous diffusion paste and firing in an infrared belt furnace. Spreading resistance measurement from a beveled sample is used to measure carrier concentration as a function of depth for different phosphorous concentrations. Contours of estimated sheet resistance are shown for different processing conditions. This paper describes newly developed low cost phosphorous pastes. It shows the characterization of the newly developed phosphorous paste (DP99-038). This low cost pastes can easily be printed and make 16% efficiency.

• ETRI Journal
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• v.18 no.4
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• pp.215-227
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• 1997

We propose a new method to eliminate completely the redundant elements in a CDMA (code division multiple access) mobile system. First, we define multilevel logic operation (MLO), which is a new concept to deal with the multilevel logic signals. We prove that the conventional binary logic concept is a subset of the MLO concept. The multilevel logic signal can be directly controlled by using this MLO in place of the binary operation. We applied the MLO to the CDMA base station modulator (BSM) in order to reduce the hardware complexity. In the case of a 3-sectorized cell, this method helps reduce the complexity down the level of below 1% of the conventional CDMA BSM for spreading and filtering, and to 50% for Walsh covering.