• BMB Reports
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• v.34 no.1
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• pp.66-72
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• 2001

To investigate the mechanism of adriamycin (ADM) resistance in the ADM resistant subline PC-14/ADM, we examined the expressions of p-glycoprotein (P-gp), topoisomerase I (Topo I) and II (Topo II), glutathione-S-transferases (GSTs), tissue transglutaminase (t-TG), epidermal growth factor receptor (EGFR), and E-cadherin and the activity of superoxide dismutase (SOD) in PC-14 and PC-14/ADM cells. There was no change in the cellular levels of P-gp, Topo I, Topo II, and the two isoforms of GSTs. However, SOD activity in PC-14/ADM cells was 2.38 fold higher than that in PC-14 cells. A marked induction of the t-TG expression was also observed in PC-14/ADM cells. In addition to those changes, expressions of EGFR and E-cadherin were down regulated in PC-14/ADM cells. Therefore, molecular modifications such as an increase in SOD activity, induction of the t-TG expression, and down regulation of EGFR and E-cadherin expressions may play important roles in PC-14/ADM cells during the development of ADM resistance.

• Journal of Korea Foundry Society
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• v.26 no.1
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• pp.34-39
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• 2006

In the present study, the possibility of Mg-Zn-Y alloys as high temperature casting alloys has been investigated. The fluidity of alloys containing yttrium were better than that of commercial AZ91 alloy because the oxide layer on the surface reduced the reaction between melt, and air and mold, which would reduce the resistance during the process of filling the mold. However, this oxide film reduced the hot-tearing resistance. In the case of ZAW942, this alloy exhibited fluidity and hot-tearing resistance better than AZ91 alloy. Because of thermally stable quasicrystal and other phases obstructed the movement of grains, the creep resistance of alloys containing rare earth elements more than 2 wt% was better than that of AZ91 alloy.

• Corrosion Science and Technology
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• v.6 no.1
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• pp.1-6
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• 2007

Ferritic stainless steels for the SOFC interconnect applications are required to possess not only a good oxidation resistance, but also a high electrical conductivity of the oxide scale that forms during exposure at the SOFC operating environment. In order to understand the effects of alloying elements on the oxidation behavior of ferritic stainless steels and on the electrical properties of oxide scales, two kinds of commercial ferritic stainless steels, STS 430 and STS 444, were investigated by performing isothermal oxidations at $800^{\circ}C$ in a wet air containing 3% $H_{2}O$. The results showed that STS 444 was superior to STS 430 in both of the oxidation resistance and the area specific resistance. Although STS 444 contained a less amount of Mn for the $(Mn,Cr)_{3}O_{4}$ spinel formation than STS 430, the minor alloying elements of Al and Mo in STS 444, which were accumulated in the base metal region adjacent the scale, were suggested to reduce the scale growth rate and to enhance the scale adherence to the base metal.

• Parasites, Hosts and Diseases
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• v.44 no.2 s.138
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• pp.163-166
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• 2006

The present study observed the resistance to reinfection with Clonorchis sinensis in various experimental animals including mice, guinea pigs, rabbits, and dogs, as well as rats and hamsters. The resistance rates to reinfection in rats, mice, hamsters, guinea pigs, rabbits, and dogs were 79.7%, 58.0%, -12.6%, 54.8%, 62.6%, and 6.0%, respectively. Worms recovered from reinfected rats and mice were immature, and significantly smaller than those from the primarily infected (P < 0.01), whereas those from other animals were fully matured to adults. These findings indicate that the protective response against reinfection with C. sinensis is prominent in rats and mice, and that they may be a good animal model to investigate the mechanism of resistance to reinfection with C. sinensis.

• Journal of the Society of Naval Architects of Korea
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• v.60 no.5
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• pp.332-340
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• 2023

The present study established hull form optimization for small catamaran based on variations of knuckle lines. Four knuckle lines below the free surface were employed as design variables. Knuckle lines were independently transformed within remaining the main dimensions of the existing hull. For the hull form optimization, the SHERPA algorithm of HEEDS was utilized. Computational fluid dynamics was employed to estimate the resistance performance. The optimal hull showed the improvement of resistance performance of 9.3% than that of existing hull. The improvement of wave and pressure distributions for optimal hull was confirmed. Throughout the present study, it is expected that established optimization method can be applied for various small vessels such as fishing and leisure boats.

• The Plant Pathology Journal
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• v.25 no.4
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• pp.408-416
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• 2009

A molecular survey was conducted to identify the presence of the bacterial blight resistance genes (Xa1, Xa4, xa5, xa13 and Xa21) in 86 accessions of aromatic rice obtained from germplasm. The results revealed that the resistance gene Xa4 (32.5%), Xa21 (17%), and xa5 (16%) were widely observed in tested rice germplasm. Among tested rice germplasm, 49 accessions showed the presence of more than one of five R genes, and 37 accessions possessed none of the R gene. TALLi and 05-IRRi-M-46 showed the presence of Xa4, xa5, xa13 and Xa21. Rice race $415{\times}Ir352$ exhibited positive amplicon for the Xa1, Xa4, xa5 and Xa21. Hyangmibyeo1hos, Ir841-85-1-1-2 and Jasmine85 showed the positive amplicon for the Xa1, Xa4 and xa5 genes. Yekywin Yinkya Hmwe and Khao Dawk Mali105 showed the presence of Xa1, Xa4 and Xa21 gene. Masino Basmati showed the presence of xa5, xa13, Xa21 genes. Xa1 and Xa21 genes were noticed in Mihayngbyeo, Tarana Deshi, Mayataung and AZUCENA. Hyangmibyeo2ho, Basmati 6311 and Basmati405 possessed only two R genes such as Xa4 and xa5, and xa5 and xa13, respectively. The evaluation results of bacterial blight resistance genes in aromatic rice germplasm will help in breeding of multi disease resistant varieties.

• Proceedings of the Korean Society of Plant Pathology Conference
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• 2003.10a
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• pp.101.2-102
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• 2003

The ability of P. chlororaphis O6 to induce resistance to Erwinia carotovora subsp. carotovara SCCI and to promote growth in tobacco was demonstrated in microtiter assays on plants pre-inoculated at the root level with the bacteria before challenge with the leaf pathogen. To identify th bacterial determinants involved in induced systemic resistance and plant growth promotion, cell culture of O6 grown in King's medium B was fractionated with organic solvents and purified using various columns. in vivo and in vitro assays with samples from successive fractionation steps of the O6 supernatant led to the conclusion that antibacterial compounds were observed in aqueous layer, and to the isolation of fractions containing metabolites that retained most of the resistance-inducing activity (70：30, methanol：water) and the plant growth promotion (80：20 and 90：10, methanol：water) after ODS column chromatography. Although these molecules remain to be purified further and structurally characterized, its isolation is an addition to the range of determinants from plant growth-promoting rhizobacteria known to stimulate plant defence.

• Korean Journal of Materials Research
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• v.24 no.4
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• pp.175-179
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• 2014

Ti and Ti alloys have been extensively used in the medical and dental fields because of their good corrosion resistance, high strength to density ratio and especially, their low elastic modulus compared to other metallic materials. Recent trends in biomaterials research have focused on development of metallic alloys with elastic modulus similar to natural bone, however, many candidate materials also contain toxic elements that would be biologically harmful. In this study, new Ti based alloys which do not contain the toxic metallic components were developed using a theoretical method (DV-$X{\alpha}$). In addition, alloys were developed with improved mechanical properties and corrosion resistance. Ternary Ti-Ag-Zr alloys consisting of biocompatible alloying elements were produced to investigate the alloying effect on microstructure, corrosion resistance, mechanical properties and biocompatibility. The effects of various contents of Zr on the mechanical properties and biocompatibility were compared. The alloys exhibited higher strength and corrosion resistance than pure Ti, had antibacterial properties, and were not observed to be cytotoxic. Of the designed alloys' mechanical properties and biocompatibility, the Ti-3Ag-0.5Zr alloy had the best results.

• 한국태양에너지학회:학술대회논문집
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• 2011.11a
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• pp.56-59
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• 2011

The process conditions for high efficiency industrial crystalline Si solar cells with selective emitter were optimized. In the screen printed solar cells, the sheet resistance must be 50-60V/sq. because of metal contact resistance. But the low sheet resistance causes the increase of the recombination and blue response at the short wavelength. Therefore, the screen printed solar cells with homogeneous emitter have limitations of efficiency, and this means that the selective emitter must be used to improve cell efficiency. This work demonstrates the feasibility of a commercially available selective emitter process, based on screen printing and conventional diffusion process. Now, we improved cell efficiency from 18.29% to18.45% by transition of heavy emitter pattern and shallow emitter doping condition.

• Transactions of the Korean Society of Automotive Engineers
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• v.22 no.5
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• pp.5-12
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• 2014

Weatherstrip coatings of urethane and silicon type which are fit to EPDM and thermoplastic materials are used in sealing systems for automotive applications for noise reduction and high slip characteristics for external applications, respectively. Polyurethane binder was successfully synthesized from poly(butyladiphate)diol (PBAD), poly(tetramethylene)glycol (PTMG) and isocyanate as starting materials. Then, polyurethane coating agents were prepared by using various additives. To investigate effects of segment types on the abrasion resistance of polyurethane coating agents, thin films based on polyurethane coating materials were fabricated. With increasing the amount of hard segment in the coating agent, abrasion resistance, modulus and tensile strength of the coating films were improved, but the elongation of the coating films was decreased.