• KSBB Journal
• /
• v.14 no.2
• /
• pp.174-180
• /
• 1999

An actinomycetes strain No.4 which produce the cholesterol oxidase(EC 1.1.3.6), was isolated from soil and identified as Streptomyces sp. based on taxonomic studies. The conditions of cholesterol oxidase production and enzymatic properties were investigated. The optimum composition of medium for production of the enzyme was 1% soluble starch, 2% corn steep liquor, 0.1% $KH_2PO_4$, 0.1% $NaNO_3$ and 0.05% $MgSO_4$ (pH 7.0). The optimum pH and temperature of the cholesterol oxidase were pH 6.0~7.5 and $37^{\circ}C$, respectively. The enzyme was stable in the range of pH 6.0~9.0. The isoelectric point determined by multichambered electrofocusing unit was in the range of pH 6.0~6.5.

• Journal of Technologic Dentistry
• /
• v.38 no.2
• /
• pp.63-68
• /
• 2016

Purpose: The purpose of this study was to assess the internal fitness of the PMMA 3-unit bridge that was fabricated with 5-axis milling machine and to verify the clinically allowable values. Methods: For fabrication of the crown bridge in this study, 25-27 abutment teeth were used. The prepare abutment teeth were scanned with a scanner and 3-unit bridge was designed by using design software. Upon the completion of the design, the 3-unit bridge was fabricated by using a PMMA block with 5-axis milling machine. The internal surface of the fabricated 3-unit bridge was scanned by using a scanner and the difference between the 3-unit bridge and the abutment teeth was assessed by merging them together. Results: $RMS{\pm}SD$ values for PRE group, MOL group, and BRI group were $51.2{\pm}18.2$, $44.8{\pm}10.0$, and $52.1{\pm}8.3{\mu}m$, respectively. The mean of the PRE group was bigger than that of the MOL and BRI group; however, statistically significant difference was not found (p>0.05). Conclusion: The PMMA 3-unit bridge that was fabricated with 5-axis milling machine presented stable internal values for each crown and overall internal values were within the range of clinically allowable values.

• Journal of Microbiology and Biotechnology
• /
• v.9 no.4
• /
• pp.429-435
• /
• 1999

An adenosine 5'-monophosphate deaminase (AMP aminohydrolase, EC 3.5.4.6) was purified to homogeneity from the cell-free extract of Saccharomyces cerevisiae DKCTC7248. The molecular mass of subunit was estimated to be 80 kDa on SDS-PAGE, and that of the holoenzyme was shown to be 240 kDa by gel filtration. The isoelectric point of the enzyme (AMP deaminase D) was determined to be 6.2. The AMP deaminase D was specific towards AMP with an apparent $K_m$ value of 4.1 mM and a Hill coefficient, $n_H$, of 2.2. Both ATP and ADP were positive allosteric effectors of the AMP deaminase D: The apparent $K_{m}$ was decreased to 1.6 mM and 3.3 mM in the presence of 0.1 mM ATP and ADP, respectively, lowering $n_{H}$ to 1.0. Univalent cations like $K^+, Na^+ and Li^ +$ activated the enzyme but some divalent cations such as $Cu^{ 2+} and Cd^{2+}$ showed strong inhibitory effects. This enzyme displayed optimum activity at $30^{\circ}C$ and pH 7.0. In addition, it was stable up to $45^{\circ}C$ and over a wide pH range(pH 5.5-9.0). Amino acid sequences of its N-terminal region were analyzed to be ADYKMQMFADDA.

• Journal of the Korean Society for Precision Engineering
• /
• v.31 no.1
• /
• pp.43-50
• /
• 2014

This paper introduces a robot platform which can do weeding while traveling between rice seedlings stably against irregular land surface of a paddy field. Also, an autonomous navigation technique that can track on stable state without any damage of the seedlings in the working area is proposed. Detection of the rice seedlings and avoidance knocking down by the robot platform is achieved by the sensor fusion of a laser range finder (LRF) and an inertial measurement unit (IMU). These sensors are also used to control navigating direction of the robot to keep going along the column of rice seedling consistently. Deviation of the robot direction from the rice column that is sensed by the LRF is fed back to a proportional and derivative controller to obtain stable adjustment of navigating direction and get proper returning speed of the robot to the rice column.

• Fibers and Polymers
• /
• v.1 no.1
• /
• pp.12-17
• /
• 2000

Thermotropic polyurethanes were synthesized from 1,6-hexane diisocyanate (HDI) as a diisocyanate, 1,6-hexane diol (HD), and rigid diols containing imide unit such as N,N＇-bis(4-hydroxyphenyl)-3,4,3＇,4＇-biphenyl-dicarboxyimide (BPDI) or bis-N-(4-hydroxyphenyl)-4,4＇-oxydiphthalimide (ODPI). The effects of structure difference between BPDI and ODPI and composition of HD/BPDl (ODPI) on the thermal and liquid crystalline behavior were studied. Thermotropic polyurethanes with an inherent viscosity of 0.59~0.70 were obtained. The melting temperature of BPDI-based polyurethanes were in the range of 150~$290^{\circ}C$, however, those of ODPI-based polyurethanes were in the range of 150~$190^{\circ}C$. All the polyurethanes based on ODPI (25~100 mole %) clearly exhibited a stable liquid crystalline phase, and BPDI-based polyurethane having 5-25% of BPDT showed a mesophase. The melting and isotropization temperatures ($T_m$, $T_i$) and ΔT($T_i$ - $T_m$) increased with increasing BPDI and ODPI content. The polyurethanes based on BPDI has higher melting points and thermal stability compared to ODPI-based polyurethanes.

• Journal of Korea Society of Industrial Information Systems
• /
• v.21 no.1
• /
• pp.61-70
• /
• 2016

This paper describes a new PMU(parametric measurement unit) design technique for automatic test equipment(ATE). Only one DDA(differential difference amplifier) is used to force the test signals to DUT(device under test), while conventional design uses two or more amplifiers to force test signals. Since the proposed technique does not need extra amplifiers in feedback path, the proposed PMU inherently guarantees stable operation. Moreover, to measure the response signals from DUT, proposed technique also adopted only one DDA amplifier as an IA(instrument amplifier), while conventional IA uses 3 amplifiers and several resistors. The DDA adopted two rail-to-rail differential input stages to handle full-range differential signals. Gain enhancement technique is used in folded-cascode type DDA to get open loop gain of 100 dB. Proposed PMU design enables accurate and stable operation with smaller hardware and lower power consumption. This PMU is implemented with 0.18 um CMOS process and supply voltage is 1.8 V. Input ranges for each force mode are 0.25~1.55 V at voltage force and 0.9~0.935 V at current force mode.

• Fisheries and Aquatic Sciences
• /
• v.6 no.1
• /
• pp.7-12
• /
• 2003

Chitinase and chitobiase produced by Aeromonas sp. J-5003 were purified and characterized. The chitinase was purified to 19.4 folds by gel chromatography and ion-exchange chromatography with the overall yield of $2.2\%$ and the specific activity of 93.1 unit/mg. The purified enzyme showed a single band on SDS-PAGE with MW 54kDa. The optimum pH and temperature of the purified chitinase were 7.0 and $37^{\circ}C$, respectively, and this enzyme stable in the range of pH 6.0 to 10.0 below $37^{\circ}C$. $Mg^{2+},\;Ca^{2+}\;and\;Na^+$ slightly stimulated the chitinase activity. However, $Hg^{2+}\;and\;Fe^{3+}$ inhibited chitinase activity. The chitobiase was purified by Sephacryl HR-l00 gel chromatography and DEAE-Sephadex A-50 ion-exchange chromatography with 33.5 purification folds and $4.3\%$ yield. The purified enzyme showed a single band with MW 63 kDa. The optimum pH and temperature of the purified chitobiase were 7.0 and $37^{\circ}C$, respectively. And this enzyme was stable in the range of pH 6.0 to 9.0 and at the temperature below $37^{\circ}C$. The enzyme activity was increased by $Mn^{2+}$, but it was inhibited by $Ag^+$.

• Journal of the Korean Ceramic Society
• /
• v.29 no.9
• /
• pp.729-738
• /
• 1992

The glass formation and structural change with the glass compositions were investigated in the CaO-P2O5-SiO2 system with less than 40 wt% of P2O5. The glass formation range was determined by XRD, SEM and EDS techniques for water quenched specimens. The structural analyses were made for binary CaO-SiO2 glasses and ternary CaO-P2O5-SiO2 glasses by using FT-IR and Raman spectroscopy. The glass formation was affected by CaO/SiO2 mole ratio, P2O5 content and primary crystalline phase. The stable glass formation range was found when the transformed CaO/SiO2 mole ratio (new factor derived from structural changes) was in the range of 0.72~1.15 with less than 10 mol% of P2O5. The structural analyses of CaO-SiO2 glasses indicated that as the CaO/SiO2 ratio was increased, the nonbridging oxygens in the structural unit of the glasses were increased. With addition of P2O5 to CaO-SiO2 glasses, the P2O5 enhanced the polymerization of [SiO4] tetrahedra unit in CaO-SiO2 glasses, which contained a large portion of nonbridging oxygen. The phosphate eliminated nonbridging oxygens from silicate species, forcing polymerization of silicate structures and produced in [PO4] monomer in glasses. When added P2O5 was kept constant, the structural change with various CaO/SiO2 ratio was very similar to that of CaO-SiO2 glasses.

• Journal of Microbiology and Biotechnology
• /
• v.8 no.6
• /
• pp.618-624
• /
• 1998

The culture conditions for Bacillus sp. DP-152 in the flask were investigated for the production of polysaccharide locculant, DP-152. The optimum pH and temperature for the locculant production were 8.0 and $30^{\circ}C$, respectively. The avorable substrates for flocculant production were soluble tarch and ammonium nitrate. The medium composition was optimized as follows: 30 g soluble starch, 0.75 g $NH_4NO_3,\; 2.0g\; K_2\;HPO_4,\; 0.1\; g KH_2PO_4,\; 0.2g\; MgSO_4.\; 7H_2O,\; and\; 0.2g\; MnSO_4~5H_2O$ in 11 of distilled water. Under this optimized condition, flocculating activity has been improved 4-fold compared with that of the basal medium. In the culture flask, the highest flocculating activity was obtained after 70 h of cultivation and the amount of bioflocculant DP-152 yielded was 12.4 g/$\ell$. The solution of bioflocculant DP-152 showed non-Newtonian characteristics. Bioflocculant DP-152 exhibited apparently higher viscosity at all concentrations compared to that of zooglan (from Zoogloea ramigera), and it was stable over a wide range of temperatures and pHs.

• Food Science and Biotechnology
• /
• v.17 no.4
• /
• pp.766-771
• /
• 2008

The proteolytic enzyme from Saccharomyces sp. B101 was purified to homogeneity by ammonium sulfate fractionation, ultrafiltration, diethyl aminoethyl (DEAE)-Sephadex A-50 ion-exchange chromatography, and Sephadex G-100 gel filtration chromatography from the culture supernatant of Saccharomyces sp. B101. The specific activity and the purification fold of the purified enzyme were 4,688.9 unit/mg and 18, respectively. The molecular weight of the purified enzyme was estimated to be 33 kDa by sodium dodecylsulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The optimum pH and temperature for the enzyme activity were pH 8.5 and $30^{\circ}C$, respectively. The enzyme activity was relatively stable in the pH range of 6.5-8.5 at below $35^{\circ}C$. The salt-tolerance and stability for the enzyme activity were relatively stable even at NaCl concentrations of 10 and 15%. The activity of enzyme was inhibited by $Ag^{2+}$ and $Fe^{2+}$, and activated by $Mn^{2+}$. In addition, the enzyme activity was potently inhibited by ethylenediaminetetraacetic acid (EDTA) and phenylmethyl sulfonylfluoride (PMSF). Based on these findings we concluded that the purified enzyme was a serine protease. Km and Vmax values for hammastein milk casein were 1.02 mg/mL and 278.38 unit/mL, respectively.