• 한국세라믹학회지
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• 제42권12호
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• pp.833-841
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• 2005

The oxidation resistance and electrical conductivity of various commercial ferritic stainless steels including STS444 were tested in an air atmosphere at $700^{\circ}C$. Crofer22 developed specially for SOFC interconnect was also examined for the aim of comparing with the test results of STS444. Although STS444 exhibited higher oxidation resistance than Corfer22, the electrical conductivity of the scale formed on Crofer22 was higher, indicating that the resistivity of scale formed on Crofer22 is much lower than that of STS444. To gain a better understanding of the relation between oxidation behavior and electrical conductivity, the oxide scales formed on STS444 and Crofer22 were analyzed in terms of the structure, composition, and phase. Consequently, the influence of alloying elements on electrical conductivity of Fe-Cr alloys was discussed.

• 한국환경보건학회지
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• 제38권5호
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• pp.415-423
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• 2012

Objectives: This study was performed in order to evaluate antibiotic resistance and analyze the multiple antibiotic resistance of food-borne pathogens isolated from indoor air and an air cleaner at a lunch room in a child care center. Methods: An antibiotic test of food-borne pathogens, including four Staphylococcus aureus and 23 Bacillus cereus was conducted through the disk diffusion method from Clinical and Laboratory Standard Institute. Results: All Staph. aureus was resistant to Ampicillin and Penicillin, while B. cereus was also resistant to Ampicillin, Cefepime and Penicillin. All isolates showed Vancomycin susceptibility but three out of four Staph. aureus and all B. cereus were resistant to Oxacillin. Staph. aureus and B. cereus presented two or more multiple antibiotic resistances. Conclusions: The results indicated that food-borne pathogens isolated from indoor air and an air cleaner at a lunch room in a child care center showed multiple antibiotic resistances. The repeated control of indoor environment quality is required and continuous surveillance of antibiotic resistant strains is demanded.

• International Journal of Naval Architecture and Ocean Engineering
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• 제3권1호
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• pp.105-110
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• 2011

Some research work on CFD computation of ship motions and added resistance in waves for a high speed trimaran is carried out in this paper. The governing equations, Reynolds Averaged Navier-Stokes and continuity equations are discretized by finite volume method. Volume of fluid method is adopted to deal with the nonlinear free surface. The incident waves are generated from the inflow boundary by prescribing a velocity profile resembling flexible flap wavemaker motions, and the outgoing waves are dissipated inside an artificial damping zone located at the rear part of the wave tank. In this paper, the computed results of ship motion and added resistance for a high speed trimaran are presented. The results of seakeeping experiment for the high speed trimaran carried out in CSSRC towing tank are also presented in this paper. Rather good agreements are shown between the computational and experimental results. The work in this paper provides a numerical tool for the study of seakeeping performance of high speed trimarans.

• 열처리공학회지
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• 제14권3호
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• pp.155-159
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• 2001

The thermal shock resistance has been investigated and compared in three hot-work tool steels. The resistance to thermal shock is first of all a matter of good toughness and ductility. Therefore, a proper hot-work tool steel should be characterized by high fracture strength and high temperature toughness. In this study, new test method is proposed to measure the thermal shock resistance. New method is basically based on Uddeholm' thermal shock test but some modification has been properly applied. Based on these results, some critical temperature($T_{fractures}$) at which fracture occur can be measured to characterize the thermal resistance of the materials. The specific values of ${\Delta}T$, the temperature difference between holding temperature and $T_{fractures}$, has been successfully used as a measure of the thermal shock resistance in this study, the results showed that the thermal shock method used in this study was properly modified.

• 한국물환경학회지
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• 제22권1호
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• pp.17-22
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• 2006

This study is about backwash condition and membrane fouling at continuous coagulation/ultrafiltration process in water treatment. The capacity of pilot plant was $0.06m^3/d$. The result of the test, Backwash cycle time and duration time had a significant effect on the efficiency of system and backwash. Backwash duration time was determined to be fixed in 30 seconds for the system with more than 95% recovery rate, It needed 30 minute backwash frequency. During the continuous operation, membrane fouling was analyzed by determining the filtration resistance ($R_i$) and cake layer resistance ($R_c$). At the initial stage, filtration resistance highly influenced the fouling behavior. But after 1.5 hours, cake layer resistance became more important than filtration resistant.

• 한국초전도ㆍ저온공학회논문지
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• 제24권4호
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• pp.40-45
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• 2022

The electrical/thermal stabilities and magnetic field controllability of a no-insulation (NI) high-temperature superconducting magnet are characterized by contact resistance between turn-to-turn layers, and the contact resistance characteristics are determined by properties of conductor surface and winding tension. In order to accurately predict the electromagnetic characteristics of the NI coil in a design stage, it is necessary to control the contact resistance characteristics within the design target parameters. In this paper, the contact resistance and critical current characteristics of a rare-earth barium copper oxide (REBCO) conductor were measured to analyze the effects of surface treatment conditions (roughness and oxidation level) of the copper stabilizer layer in REBCO conductor. The test samples with different surface roughness and oxidation levels were fabricated and conductor surface analysis was performed using scanning electron microscope, alpha step surface profiler and energy dispersive X-ray spectroscopy. Moreover, the contact resistance and critical current characteristics of the samples were measured using the four-terminal method in a liquid nitrogen impregnated cooling environment. Compared with as-received REBCO conductor sample, the contact resistance values of the REBCO conductors, which were post-treated by the scratch and oxidation of the surface of the copper stabilizer layer, tended to increase, and the critical current values were decreased under certain roughness and oxidation conditions.

• 한국표면공학회지
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• 제51권6호
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• pp.381-386
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• 2018

In this study, plasma electrolytic oxidation (PEO) method was used to from anodic oxide films on Al alloy and their resistance and morphological characteristics were investigated as a function of film formation voltage and treatment time. Cross-sectional morphology and composition of the PEO films were analyzed by SEM (Scanning Electron Microscopy) and EDS (Energy Dispersive Spectroscopy). The PEO films showed increased surface roughness and thickness with of film formation voltage and treatment time. The wear resistance was found to be the best for the PEO film formed for 5 min at 500V which is attributed to be denser structure relatively and lower surface roughness.

• The Plant Pathology Journal
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• 제40권2호
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• pp.151-159
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• 2024

Bacterial soft rot caused by Pectobacterium carotovorum subsp. carotovorum (Pcc) is one of the most severe diseases in radish cultivation. To control this plant disease, the most effective method has been known to cultivate resistant cultivars. Previously, we developed an efficient bioassay method for investigating resistance levels with 21 resistant and moderately resistant cultivars of radish against a strain Pcc KACC 10421. In this study, our research expanded to investigate the resistance of radish cultivars against six Pcc strains, KACC 10225, KACC 10421, ATCC 12312, ATCC 15713, LY34, and ECC 301365. To this end, the virulence of the six Pcc strains was determined based on the development of bacterial soft rot in seedlings of four susceptible radish cultivars. The results showed that the Pcc strains exhibited different virulence in the susceptible cultivars. To explore the race differentiation of Pcc strains corresponding to the resistance in radish cultivars, we investigated the occurrence of bacterial soft rot caused by the six Pcc strains on the 21 resistant and moderate resistant cultivars. Our results showed that the average values of the area under the disease progress curve were positively correlated with the virulence of the strains and the number of resistant cultivars decreased as the virulence of Pcc strains increased. Taken together, our results suggest that the resistance to Pcc of the radish cultivars commercialized in Korea is more likely affected by the virulence of Pcc strains rather than by race differentiation of Pcc.

• The Plant Pathology Journal
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• 제26권3호
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• pp.273-279
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• 2010

We evaluated 209 Capsicum accessions from the National Agrobiodiversity of RDA, for their reaction against of anthracnose disease caused by Colletotrichum acutatum. Two hundred nine accessions of Capsicum were almost composed with Capsicum annuum var. annuum originated from 37 countries. The percentage of infection due to C. acutatum ranged from 11.1% to 100% on immature and matured pepper fruits at 21 days after inoculation. On immature fruits of pepper, one hundred seventy three accessions of tested pepper were found infected with C. acutatum. Out of the 173 accessions, eighty five accessions were susceptible to anthracnose with dark brown to black lesions and slowly increased in size at 21 days after inoculation. Only thirty six accessions showed resistance against C. acutatum. On mature fruits of pepper, one hundred ninety eight accessions were infected with C. acutatum at 21 days after inoculation. Twenty one accessions showed a resistance reaction against C. acutatum. The results of this work indicated that all of resistance accessions to C. acutatum were have a genetic potential for the resources of resistance can be further used in pepper breeding programme against anthracnose and also demand more detailed investigation in this.

• 한국표면공학회지
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• 제44권5호
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• pp.226-231
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• 2011

Graphene was coated on STS 316L by electro spray coating method to improve its properties of corrosion resistance and contact resistance. Exfoliated graphite (graphene) was made of the graphite by chemical treatment. Graphene is distributed using dispersing agent, and STS 316L was coated with diffuse graphene solution by electro spray coating method. The structure of the exfoliated graphite was analyzed using XRD and the coating layer of surface was analyzed by using SEM. Analysis showed that multi-layered graphite structure was destroyed and it was transformed into fine layers graphene structure. And the result of SEM analysis on the surface and the cross section, graphene layer was uniformly formed with 3~5 ${\mu}m$ thickness on the surface of substrate. Corrosion resistance test was applied in the corrosive solution which is similar to the PEM fuel cell stack inside. And interfacial contact resistance test was measured to simulate the internal operating conditions of PEM fuel cell stack. The results of measurements show that stainless steel coated with graphene was improved in corrosion resistance and surface contact resistance than stainless steel without graphene coating layer.