• Microbiology and Biotechnology Letters
• /
• v.37 no.4
• /
• pp.350-354
• /
• 2009

A Gram-negative, alginate lyase-producing bacterium was isolated from the Haeundae Coast, Korea. The isolated strain N7151-6 produced alginate lyase. The optimal temperature and pH for growth were found to be $30^{\circ}C$ and pH 8.0, respectively. This strain can be grown at the NaCl concentration of 0-7% (w/v). Analysis of 16S rDNA sequence and physiological profiling indicated that the strain N7151-6 belonged to Pseudomonas sp. The enzyme alginate lyase produced by Pseudomonas sp. N7151-6 was partially purified by ultrafiltration (MWCO= 30 kDa). The optimum pH and temperature for the activity of the purified enzyme were found to be 7.0 and $30^{\circ}C$, respectively. The enzyme was stable at the pH range of 5.0-9.0 and temperature range of $23-30^{\circ}C$. The total activity of alginate lyase produced was reached about 110 unit/L.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
• /
• v.8 no.4
• /
• pp.293-301
• /
• 2010

Optical fiber cable, as a sensor, was installed on the wall of KAERI(Korea Atomic Energy Research Institute) Underground Research Tunnel(KURT) in order to monitor the physical stability of the tunnel, which was constructed for technical development and demonstration of radioactive waste disposal. This monitoring system has two simultaneous measurements of temperature and strain over time using Brillouin backscatter. According to the results of the monitoring from Jan. 2008 to Nov. 2009, there is no significant displacement or movement at the tunnel wall However, the cumulative volume of total strain increased slightly as time passes with the comparison of the reference observation, which was measured in Jan. 2008. The change in cumulative volume of total strain indicates that the strain level had been affected by saturation and de-saturation phenomena due to groundwater fluctuation at several points at KURT. This system is based on the distributed sensing technique concept, not point sensing. By using this system, a displacement can be detected with the range from $20{\mu}{\varepsilon}$ to $28,000{\mu}{\varepsilon}$ every 1m interval in minimum. A temperature variation can be monitored at every 0.5m interval with the resolution of 0.01 in minimum. Based on the study, this monitoring system is potentially applicable to long term monitoring systems for radioactive waste disposal project as well as other structures and underground openings.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.8 no.3
• /
• pp.195-200
• /
• 1984

In-plane tension fatigue tests(R=0.1) were carried out to investigate the initiation and growth behaviors of very small surface fatigue cracks on smooth unnotched surfaces of type 304 stainless steel at room temperature. The present paper deals with the unification of two approaches to the analysis of fatigue: the one approach is based on fracture mechanics concept and the other on low-cycle fatigue concept. The results are;(1)Maximum crack length, 2 $a_{max}$, initiated at a very small surface scratch not exceeding 20 .mu.m which can exist on the surface after buffing. And the density of small surface crack is remarkably low compared to that of mild steel. (2) The growth rate, d(2a)/dN, of very small fatigue cracks can be represented by one straight line as a function of either stress intensity factor range, .DELTA. $K_{I}$ or cyclic total strain intensity factor range, .DELTA. $K_{\epsilon}$$_{I}$/, for various values of the nominal stress range.e.e.e.e.

• Microbiology and Biotechnology Letters
• /
• v.16 no.5
• /
• pp.352-357
• /
• 1988

Twenty-five out of 35 strains isolated from fermented corn meal produced folic acid. Bacillus licheniformis strain 6 and Enterobacter cloacae strain 18 produced the largest quantities of 1830$\pm$271 ng and 1350$\pm$161 ng per 100$m\ell$ of the assay broth, respectively. B. licheniformis produced maximum yields when initial pH values were 6,7, or 8 and were incubated at 35$^{\circ}C$ for 5 days. The initial pH (range 4-8) had no effect on folic acid production by E. cloacae； 55 $^{\circ}C$ for 5 days was optimal for this bacterium. Added carbohydrates had no effect on the production of total folic acid in the bacterial cells in pure or mixed cultures. However, in their growth media, carbohydrates enhanced the production of free and total folic acid by E. cloacae and in the mixed cultures. Added carbohydrates had no significant (P < 0.05) effect on the production of free and total folic acid by B. licheniformis.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.35 no.7
• /
• pp.753-758
• /
• 2011

The Ni-base super-heat-resistant alloy, GTD-111, is employed in gas turbines because of its high temperature strength and oxidation resistance. It is important to predict the fatigue life of this superalloy in order to improve the efficiency of gas turbines. In this study, low-cycle fatigue tests are performed as variables of total strain range and temperature. The relationship between the strain energy density and number of cycles to failure is examined in order to predict the low-cycle fatigue life of the GTD-111 superalloy. The fatigue life predicted by using the strain-energy methods is found to coincide with that obtained from the experimental data and from the Coffin-Manson method.

• Journal of the Korean Society for Heat Treatment
• /
• v.32 no.3
• /
• pp.107-112
• /
• 2019

In order to investigate the effect of plastic deformation and annealing process parameters on strength and electrical conductivity of Cu-Fe alloys, Cu-10wt%Fe, Cu-15wt%Fe alloys were drawn up to ${\eta}=4$ and annealed in the temperature range of $300^{\circ}C$ to $700^{\circ}C$, followed by measurements of tensile strength and electric conductivity. As draw strain increases, tensile strength increases while electrical conductivity decreases. These observations result from reduction of dislocation density and decrease in Fe fiber spacing. Raising annealing temperature brought about decrease of tensile strength and increase of electrical conductivity up to $500^{\circ}C$, being followed by decreasing above $500^{\circ}C$. Such results are thought to be caused by decrease of dislocation density below $500^{\circ}C$ and rapid solubility increase of Fe in Cu above $500^{\circ}C$. For the purpose of obtaining both high strength and high conductivity, annealing process should be incorporated just prior to reaching to final draw strain. For Cu-10wt%Fe alloy, the tensile strength 706.9 MPa and the electrical conductivity 54.34%IACS were obtained through the processes of drawing up to ${\eta}=3$, annealing at $500^{\circ}C$ for 1 hour and additional drawing up to total strain of ${\eta}=4$.

• Journal of the Korean Society for Heat Treatment
• /
• v.37 no.2
• /
• pp.79-85
• /
• 2024

The effects of annealing heat treatment and the addition of Cu element on the shape memory effect of the NiTi-based alloy were investigated by analyzing differential scanning calorimeter results and characterizing recovery rate through 3D scanning after Vickers hardness test. Through 3D scanning of impressions after Vickers hardness test, the strain recovery rates for specimens without annealing treatment and annealed specimens at 400, 450, and 500℃ were measured as 45.96%, 46.76%, 52.37%, and 43.57%, respectively. This is because as the annealing temperature increases, both B19' and NiTi₂ phases, which can impede martensitic transformation, are incorporated within the NiTi matrix. Particularly, additional phase transformation from R-phase to B19' observed in specimens annealed at 400 and 450℃ significantly contributes to the improvement in strain recovery rates. Additionally, the results regarding the Cu element content indicate that when the total content of Ni and Cu is below 49.6 at.%, the precipitation of fine B19' and NiTi₂ phases within the matrix can greatly influence the transformation enthalpy and temperature range, resulting in relatively lower strain recovery rates in NiTi alloys with a small amount of Cu element produced in this study.

• Journal of the Korean Geotechnical Society
• /
• v.18 no.4
• /
• pp.207-214
• /
• 2002

A constitutive model was implemented in ABAQUS code, The constitutive equation can model the behavior for overall range of strain level from small to large deformation, which is based on anisotropic hardening rule and total stress concept. The formulation includes (1) finite strain formulation on the basis of Jaumann rate, (2) implicit stress integration and (3) consistent tangent moduli. Therefore, the mathematical background was established in order that large deformation analysis can be performed accurately and efficiently with the anisotropic constitutive model. Companion paper(Jeon et al., 2002) will contain the large deformation analysis results of examples with the constitutive model using ABAQUS.

• Journal of Microbiology and Biotechnology
• /
• v.19 no.7
• /
• pp.734-741
• /
• 2009

Recently, strains of methicillin-resistant Staphylococcus aureus (MRSA) with reduced susceptibility to vancomycin (VCM) have been clinically isolated. The antibacterial activity of a new drug, linezolid (LZD), in such a strain was evaluated by measuring bacterial metabolic activity. A total of 73 MRSA strains having various susceptibilities to VCM were subjected to a novel and highly sensitive chemiluminescence-based assay. LZD MIC in the tested strains, measured by the microbroth dilution method, was within the range 1-4 mg/l (mostly ${\leq}2$mg/l), except for one LZD-resistant strain (NRS127; MIC=7 mg/l), and showed no correlation with VCM resistance. The chemiluminescence assay demonstrated that bacterial metabolic activity was strongly suppressed with increasing LZD concentration. The chemiluminescence intensity curve had a low baseline activity without tailing in most strains. The present results suggest that LZD has strong antibacterial activity against MRSA strains, and would be effective for treatment of infections that are poorly responsive to VCM. The chemiluminescence assay facilitated sensitive and discriminative susceptibility testing within a relatively short time.

• The Journal of Korean Society of Virology
• /
• v.29 no.2
• /
• pp.99-105
• /
• 1999

BamHI restriction pattern and genomic library of Herpes simplex virus type 2 (HSV-2) strain G were constructed, and locations of the glycoproteins gB and gD, and tk genes on the fragments were detected by Southern blot analysis. HSV-2 genomic DNAs were cleaved into twenty-seven fragments by BamHI enzyme in the range of 0.72 to 15.08 (total 150.44 kb), which were cloned into the BamHI site of pBluescript SK(+) to construct genome library of the HSV-2. The library was named by the order of the fragment size from smallest one to largest one. HSV-2 glycoprotein gD gene was located in pHLA2-21 and pHLA2-22 recombinant plasmids, gB gene in pHLA2-24 plasmid, and tk gene in pHLA2-11 clone by Southern blot analysis.