• Journal of the Computational Structural Engineering Institute of Korea
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• v.18 no.3
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• pp.311-320
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• 2005

In this paper an enhanced quadratic finite element for static and dynamic analysis of plate structures is presented. The performance of a proposed plate element is improved by the coupled use of non conforming displacement modes, the selective integration scheme, and the assumed shear strain fields. An efficient direct modification method is also applied to this element to solve the problem such as failure of the patch test due to the adoption of non conforming modes. The proposed quadratic finite element does not show any spurious mechanism and does not produce shear locking phenomena even with distorted meshes. It is shown that the results obtained by this element converged to analytical solutions very rapidly tough numerical tests for standard benchmark problems. It is also noted that this element is applicable to transient dynamic analysis of Mindlin plates.

• Journal of Welding and Joining
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• v.26 no.5
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• pp.49-59
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• 2008

Hastelloy C-276, corrosion resistant alloy at high temperature, is used in chemical plant and power generation industry. In this study, process parameter of laser welding for welding property in Hastelloy C-276 using a continuous wave Nd:YAG laser was studied. As the result of experiment, laser welding did not show segregation or crack at heat affected zone compared to conventional GTWA welding. The melting zone showed cell dendritic structure along with welding line. In addition, planer front solidification is occurred from welding structure, and it was progressed to cellular solidification. Optimal process parameter for butt welding was 1.2kW and 2.0 m/min for laser power and welding speed, respectively. While heat input, output density, tensile stress, and longitudinal strain was $441.98{\times}103$ J/cm2, $29.553{\times}103$ W/cm2, 768 MPa, and 0.689, respectively. Lap welding of the same material showed greater discrepancy in tensile property during 1 line and 2 line welding. For 1 line welding, tensile stress was about 320 MPa, and 2 line showed slightly larger tensile stress. However, strain was decreased by 20%. From this result, lap welding of the same material, Hastelloy C-276, with 2 line welding is considered to be more effective process than 1 line welding with consideration of mechanical property.

• Korean Journal of Metals and Materials
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• v.49 no.2
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• pp.121-127
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• 2011

The mechanical properties of the various heat treatment conditions on Ti-15Mo-3Nb-3Al-0.2Si alloy plates were examined. XRD patterns from the surface of Ti-15Mo-3Nb-3Al-0.2Si were analyzed as a solution-treated Ti alloy has the single-phase ${\beta}$ structure whereas the aged Ti alloys have the ${\beta}$ matrix embedded with ${\alpha}$ needles. High strength (~1500 MPa) with decent ductility (7%) was obtained by the Ti alloy double aged at $300^{\circ}C$ and $520^{\circ}C$ for 8 hours each. The double-aged alloy exhibits the finer structure than the single-aged alloy at $300^{\circ}C$ for 8 hours because of the higher nucleation rate of ${\alpha}$ needles at an initial low aging temperature ($320^{\circ}C$). TEM observation revealed that the fine nanostructure with ${\alpha}$ needles in the ${\beta}$ matrix ensured the excellent mechanical properties in the double aged Ti-15Mo-3Nb-3Al-0.2Si alloy. In the solution treated alloy, the yield drop, stress-serrations and the ductility minimum typically associated with dynamic strain aging can be attributed to the dynamic interaction between dislocations and oxygen atoms. The yield drop and the stress serration were not observed in aged samples because the geometrically introduced dislocations due to phase precipitates suppressed the dynamic strain aging.

• Journal of Cardiovascular Imaging
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• v.31 no.4
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• pp.200-206
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• 2023

BACKGROUND: Right ventricular (RV) dysfunction is a significant risk of major adverse cardiac events in patients with acute heart failure (AHF). In this study, we evaluated RV-pulmonary artery (PA) coupling, assessed by tricuspid annular plane systolic excursion (TAPSE)/pulmonary artery systolic pressure (PASP) and assessed its prognostic significance, in AHF patients. METHODS: We measured the TAPSE/PASP ratio and analyzed its correlations with other echocardiographic parameters. Additionally, we assessed its prognostic role in AHF patients. RESULTS: A total of 1147 patients were included in the analysis (575 men, aged 70.81 ± 13.56 years). TAPSE/PASP ratio exhibited significant correlations with left ventricular (LV) ejection fraction(r = 0.243, p < 0.001), left atrial (LA) diameter(r = -0.320, p < 0.001), left atrial global longitudinal strain (LAGLS, r = 0.496, p < 0.001), mitral E/E' ratio(r = -0.337, p < 0.001), and right ventricular fractional area change (RVFAC, r = 0.496, p < 0.001). During the median follow-up duration of 29.0 months, a total of 387 patients (33.7%) died. In the univariate analysis, PASP, TAPSE, and TAPSE/PASP ratio were significant predictors of mortality. After the multivariate analysis, TAPSE/PASP ratio remained a statistically significant parameter for all-cause mortality (hazard ratio [HR], 0.453; p = 0.037) after adjusting for other parameters. In the receiver operating curve analysis, the optimal cut-off level of TAPSE/PASP ratio for predicting mortality was 0.33 (area under the curve = 0.576, p < 0.001), with a sensitivity of 65% and a specificity of 47%. TAPSE/PASP ratio < 0.33 was associated with an increased risk of mortality after adjusting for other variables (HR, 1.306; p = 0.025). CONCLUSIONS: In AHF patients, TAPSE/PASP ratio demonstrated significant associations with RVFAC, LA diameter and LAGLS. Moreover, a decreased TAPSE/PASP ratio < 0.33 was identified as a poor prognostic factor for mortality.

• Korean Journal of Veterinary Service
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• v.23 no.4
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• pp.313-320
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• 2000

Staphylococcus aureus is a causative pathogen of bovine mastitis. It is recognized as a common pathogen in human and animal and specially enterotoxin-producing strain of S aureus is a common cause of staphylococcal food poisoning in human. Various food originated raw milk, cheese, butter produced from mastitic cow causes staphylococcal food poisoning. It is difficult to treat the staphylococcal mastitis because of increasing resistance by using overdose of antibiotics. This study was conducted to investigate the enterotoxin-production and coagulase serotypes of S aureus in Chonnam province for 6 month, 1999. Also we studied the antibiotic resistant pattern with 14 types against isolates. 18(10.1%) S aureus were isolated from 178 raw milk samples in seven farms. and 8 strains(38%) were isolated in 21 raw milk samples which was below 500,000 somatic cells. We identify that 7(87.5%) of 8 isolates and 15(83.3%) 18 isolates produce enterotoxin. Their enterotoxin serotype was type B(66.7%), type A(33.3%) and type C(13.3%). Also 2 strains of isolates was positive to the type A and B. Coagulase serotype of isolates was 2, 3, 4, 7, and 8. Most stains(70.6%) were serotype 2. And most strains(17 isolates, 94.4%) except one isolate was multiple resistant to the tested antibiotics.

• Parasites, Hosts and Diseases
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• v.44 no.4 s.140
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• pp.313-320
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• 2006

In an effort to characterize, on the molecular scale, the Acanthamoeba initially isolated from the cornea of an amoebic keratitis patient associated with overnight-wear orthokeratology lens in Korea, we conducted mitochondrial DNA restriction fragment length polymorphism, 18S rDNA sequencing, and drug sensitivity analyses on the isolate (KA/PE1). The patient was treated with polyhexamethylene biguanide, chlorhexidine and oral itraconazole, which resulted in resolution of the patient's ocular inflammation. The majority of the molecular characteristics of the KA/PE1 were determined to be identical, or quite similar, to those of A. castellanii Ma strain, which had been isolated also from amoebic keratitis. The risk of Acanthamoeba keratitis as a potential complication of overnight orthokeratology is briefly discussed.

• Journal of Microbiology and Biotechnology
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• v.22 no.8
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• pp.1092-1100
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• 2012

Ten Bacillus strains with antimicrobial activities were isolated from Cheonggukjang produced at different parts in Korea. They all inhibited Listeria monocytogenes ATCC 19111 and nine inhibited Bacillus cereus ATCC 14579. Four isolates (W42, H27, SKE 12, and K21) showing strong inhibiting activities were identified as B. subtilis. B. subtilis W42 was the most inhibiting strain. The antimicrobial activity of culture supernatant from B. subtilis W42 was destroyed completely by proteinase K treatment, indicating that a bacteriocin was the responsible agent. The bacteriocin, Bac W42, was most stable at pH 7 and stable between pH 3-6 and 8-9. Bac W42 was stable up to $80^{\circ}C$. BHI (brain heart infusion) and TSB (tryptic soy broth) were the best media for the activity (320 AU/ml) followed by LB (160 AU/ml). Bac W42 was partially purified by column chromatographies. The specific activity was increased from 1,151.2 AU/ml to 9,043.5 AU/ml and the final yield was 26.3%. Bac W42 was 5.4 kDa in size as determined by SDS-PAGE. Bac W42 showed bactericidal activity against L. monocytogenes ATCC 19111.

• Journal of Industrial Technology
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• v.19
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• pp.313-320
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• 1999

Steel railway bridge gets vibration from moving load ; additionally, this kind of moving load is going to be a sufficient reason, which causes fatigue damage to steel railway bridge. Fatigue damage and stress curve were raised by moving load depends on span length in steel railway bridge. In other words, stress curve appears index regarding every axial load in short span, but self weight lets stress curve's change decrease in proportion to increasing span length. Thereby, we have studied that how the steel railway bridge appear fatigue damage in proportion to span length of steel railway bridge. Dynamic strain was measured in 4 steel plate-girder railway bridge during the trains was passing, which is located on the line of Kyoung-chun railway. And time history response analysis has been done in order to ensure actual survey. The results of this study show the decreased of the fatigue damage in steel railway bridge according to length of span. This paper ends is bases research of fatigue design in steel railway bridges according to span length.

• Biotechnology and Bioprocess Engineering:BBE
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• v.5 no.5
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• pp.320-326
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• 2000

Promoters of the genes G3P, ICL1, POT1, POX1, POX2 and POX5 of the yeast Y. lipolytica were studied in respect to their regulations and activities during growth on different carbon sources. The aim of this study was to select suitable promoters for high expression of heterologous genes in this yeast. For this purpose the promoters were fused with the reporter gene lacZ of E. coli and integrated as single copies into the genome of Y. lipolytica strain PO1d. The measurement of expressed activities of ${\beta}$-galactosidase revealed that pICL1, pPOX2 and pPOT1 are the strongest regulable promoters available for Y. lipolytica, at present. pPOX2 and pPOT1 were highly induced during growth on oleic acid and were completely repressed by glucose and glycerol. pICL1 was strongly inducible by ethanol besides alkanes and fatty acids, however, not completely repressible by glucose or glycerol. Ricinoleic acid methyl ester appeared as a very strong inducer for pPOT1 and pPOX2, in spite of that it inhibited growth of Y. lipolytica transformants.

• Journal of Microbiology and Biotechnology
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• v.17 no.2
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• pp.320-324
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• 2007

The removal of hydrogen sulfide ($H_2S$) from aqueous media was investigated using Thiobacillus novellas cells immobilized on a $SiO_2$ carrier (biosand). The optimal growth conditions for the bacterial strain were $30^{\circ}C$ and initial pH of 7.0. The main product of hydrogen sulfide oxidation by T. novellus was identified as the sulfate ion. A removal efficiency of 98% was maintained in the three-phase fluidized-bed reactor, whereas the efficiency was reduced to 90% for the two-phase fluidized-bed reactor and 68% for the two-phase reactor without cells. The maximum gas removal capacity for the system was 254 g $H_2S/m^3/h$ when the inlet $H_2S$ loading was $300g/m^3/h(1,500ppm)$. Stable operation of the immobilized reactor was possible for 20 days with the inlet $H_2S$ concentration held to 1,100 ppm. The fluidized bed bioreactor appeared to be an effective means for controlling hydrogen sulfide emissions.