• Food Science and Biotechnology
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• v.17 no.2
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• pp.257-261
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• 2008

Previous studies have suggested a possible correlation between cell surface hydrophobicity (CSH) and stress tolerance in Bifidobacterium. In this study, the relationship was examined between CSH and environmental stress tolerance in Lactobacillus spp. By measuring the adhesion to hexadecane, 2 Lactobacillus fermentum strains- KLB 261 and KLB 231 were found to have high and low CSH, respectively. To measure their tolerance to various stresses, cells were subjected to salt (2 M NaCl), acid (pH 2), $H_2O_2$ (0.01 %, v/v), ethanol (20%, v/v), heat ($60^{\circ}C$), and cold ($-20^{\circ}C$). Compared with KLB 231, the hydrophobic KLB 261 was found to be much more resistant to the various stresses examined. After being subjected to different stresses for a period of time, KLB 261 and KLB 231 showed 50 and 0% survivability in 2 M NaCl, 108.2 and 0.6% in 0.01 %(v/v) $H_2O_2$, 40.2%(v/v), and 3.7% at $60^{\circ}C$ incubation, 4 and 0.6% at $-20^{\circ}C$, 12.9 and 0.1 % in pH 2, 33.8 and 0.2% in 20%(v/v) ethanol, respectively. Autoaggregation test and morphological observation were also conducted in an attempt to explain these differences. These results suggested that high CSH could strengthen the stress tolerance of lactobacilli.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.43 no.12 s.354
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• pp.1-7
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• 2006

An on chip voltage down converter (VDC) using the self temperature-compensation techniques is proposed. At a different gate bias voltage, PMOSFET shows different source to drain current characteristic according to the temperature variation. The proposed VDC can reduce its temperature dependency by the source to drain current ratio of two PMOSFET with different gate bias respectively. Proposed circuit is fabricated in Dongbu-anam $0.18{\mu}m$ CMOS process and experimental results show its temperature dependency of $-0.49mV/^{\circ}C$ and external supply dependency of 6mV/V. Total current consumption is only $1.1{\mu}A@2.5V$.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2012.10a
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• pp.838-841
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• 2012

To avoid the damage to circuit and performance degradation by temperature changes, temperature sensing circuit applicable to the IC is proposed in this paper. Temperature sensing is executed by PTAT circuit and power saving mode is activated by internal switch if internal temperature is in high. Also, characteristics of current matching are increased by using current mirror and cascode circuits. From the simulation results, this circuit is operating in action mode if input signal is in low. But it immediately goes into power saving mode if output signal is in high. It shows the output voltage of 1V at $75^{\circ}C$ and 1.75V at $125^{\circ}C$ in action mode and near 0 V(0V~ 7uV) in power saving mode.

• Journal of the Korean Ceramic Society
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• v.38 no.4
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• pp.308-313
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• 2001

We report the effects of the V$_2$O$_{5}$ additive on the sintering behavior and microwave dielectric properties of ZnNb$_2$O$_{6}$ ceramics. Densification temperatures of V$_2$O$_{5}$-doped ZnNb$_2$O$_{6}$ samples are lowered to the range of 875-9$25^{\circ}C$ because of the liquid phase sintering. Doped samples are composed of a Zn(Nb,V)$_2$O$_{6}$ solid solution and second phases. Up to 5 wt% V$_2$O$_{5}$ is the only second phase, however, V$_2$O$_{5}$ also exists as the second phase for 10 wt% V$_2$O$_{5}$ addition. In comparison with reported values of undoped ZnNb$_2$O$_{6}$ ceramics, microwave properties of V$_2$O$_{5}$-doped ZnNb$_2$O$_{6}$ samples are seriously degraded, which is confirmed to originate from the second phases. The optimum microwave properties (Q$\times$f=13,800, $\varepsilon$$_{r}$=23, $\tau$$_{f}$=-66ppm/$^{\circ}C$) are obtained from ZnNb$_2$O$_{6}$ with the addition of 5 wt% V$_2$O$_{5}$ sintered at 90$0^{\circ}C$.90$0^{\circ}C$.EX>.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.22 no.1
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• pp.141-148
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• 2008

This paper presents experimental results on the safety of persons and protection of low-voltage equipments of the sub-station due to a single-phase ground fault in 22.9 kV-Y distribution system. In order to evaluate the hazard voltages and the stress voltage of the low-voltage(LV) equipment due to faults between high-voltage systems and earth based on the newly prescribed KS C IEC 60364 standard series, the verification tests in a 22.9[kV] neutral multiple grounding system were carried out. From the experimental results, we introduce serious problems causing some discomfort when applying KS C IEC 60364 standard series to the existing domestic distribution system and the effective protective measures against temporary overvoltages due to a ground fault in the common grounding which is combined the 22.9 kV-Y grounding and the customer's installation grounding are proposed. As a consequence, it was found that the equipotential bonding is an important prerequisite for the effectiveness of the protective measures for the safety of persons and LV equipment in the combined 22.9 kV-Y and low-voltage grounding system.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.15 no.4
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• pp.115-128
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• 2016

Many research activities to reduce accidents on the road and to improve traffic efficiency have been performed and almost research projects are developing technologies and services based on C-ITS technology nowadays. The main concept of C-ITS is improving road safety and traffic efficiency by sharing and reproducing information between various elements. To accomplish this goal, V2X communication technology has been adopted. In Korea, we have studied V2X communication technology in support of SMART-Highway research project and are managing test-bed to verify the developed technology recently. In this paper, we introduce SMART-Highway test-bed and show the procedure and result of V2X communication performance analysis on the test-bed.

• The Korean Journal of Physiology
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• v.26 no.1
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• pp.15-25
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• 1992

In order to elucidate the properties of the background current whole cell patch clamp studies were performed in rabbit ventricular cells. Ramp pulses of ${\pm}80\;mV$ from holding potential of 40 mV(or 20 mV) at the speed of 0.8 V/sec were given every 30 sec(or 10 sec) and current-voltage diagrams(I-V curve) were obtained. For the activation of the background current isoprenaline, adenosine 3',5'-cyclic monophosphate(dBcAMP), guanosine 3',5'-cyclic monophosphate(cGMP), and $N^6$-2'-o-dibutyryladenosine 3',5'-cyclic monophosphate(dBcAMP) were applied after all known current systems were blocked with 2mM Ba, 1 mM Cd ,5 mM Ni, 10 ${\mu}M$ diltiazem, 10 ${\mu}m$ ouabain, and 20 mM tetraethylammonium(TEA). The conductance of background current in control was $0.65{\pm}0.69$ nS at 0 mV, its I-V curves was almost linear and reversed near 50 mV. When there was no taurine in pipette solution, isoprenaline hardly activated the background current but when taurine existed in pipette solution, isoprenaline activated the larger background current. Cyclic AMP or cyclic GMP alone had little effect on the activation of the background current, while cGMP potentiated cGMP effect. When the background current was activated with cGMP and cAMP, isoprenaline could not further increased the background current. The background current activated by isoprenaline depended on extracellular $Cl^-$ concentration and its reversal potential was shifted according to chloride equilibrium potential. The change of extracellular $Na+$ concentration had little effect on reversal potential of the background current activated by isoprenaline.

• Korean Journal of Materials Research
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• v.7 no.3
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• pp.234-243
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• 1997

The crystal structure of arc melted $ZrV_{x}Mn_{1-x}Ni_{1.0},\;ZrV_{x}Mn_{0.8-x}Ni_{1.2},\;ZrV_{x}Mn_{0.6-x}Ni_{1.4}$ alloys which are known to have AB2 type Laves structure was investigated. They had mixed phases of C14 and C15. The radius ratio ($r_{A}/r_{B}$) of atoms in A site to that of B site was found to be an important parameter in explaining the omposition dependence of the crystal structure The C15 structure showed a linear increase with the ratio in as-cast conditions. However, the annealed alloys revealed a definite ratio at which the stability of both phases are divided distinctly. The composition of the alloys could be closely controlled by maintaining the argon pressure in the chamber over 1 arm during arc melting. In contrast, the alloy ingot melted in VIM showed a significant loss of hln.

• Journal of the Korean Society for Heat Treatment
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• v.4 no.2
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• pp.19-26
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• 1991

This study has been constructed to establish the formation of the VC layer on various steels by immersion in fused borax bath containing Fe-V powder. The result obtained from the experiment are as follows. (1) The carbide is supposed to grow on the front surface of the carbide layers by the reaction between carbide-forming elements dissolved in the fused borax and carbon atoms successively supplied through the layer from the matrix. (2) The growth rate of the carbide layers was controlled by the diffusion rate of C in the carbide layer and C content in the matrix. (3) Carbide layer formed on the surface of the specimen is VC layer and the hardness of this layer is above $H_v$ 3000.

• Journal of IKEEE
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• v.27 no.4
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• pp.556-560
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• 2023

In this study, the impact of Nitrogen implantation process on deep-level defects and lifetime in 4H-SiC Epi surfaces was comparatively analyzed. Deep Level Transient Spectroscopy (DLTS) and Time Resolved Photoluminescence (TR-PL) were employed to measure deep-level defects and carrier lifetime. As-grown Schottky Barrier Diodes (SBDs) exhibited energy levels at 0.16 eV, 0.67 eV, and 1.54 eV, while for implantation SBD, defects at 0.15 eV were observed. This indicates a reduction in defects associated with energy levels Z_1/2 and EH_6/7, known as lifetime killers, as impurities from nitrogen implantation replace titanium and carbon vacancies.