• The Korean Journal of Physiology and Pharmacology
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• v.11 no.5
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• pp.227-231
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• 2007

The classic type of transient receptor potential channel(TRPC) is a molecular candidate for $Ca^{2+}$-permeable cation channel in mammalian cells. TRPC5 is rapidly desensitized after activation by G protein-coupled receptor. Herein we report the effect of dimethyl sulfoxide(DMSO) on the desensitization of TRPC5. TRPC5 was initially activated by muscarinic stimulation with $50{\mu}M$ carbachol(CCh) and then decayed rapidly even in the presence of CCh(desensitization). DMSO in the pipette solution slowed the rate of this desensitization. Under the control conditions, TRPC5 current spontaneously declined to $6{\pm}1%$ of the initial peak amplitude 60 sec after CCh application and to $1{\pm}0.5%$ after 120 sec. But, in the presence of 0.01%, 0.1% and 1% DMSO, TRPC5 current spontaneously declined to $55{\pm}2%,\;68{\pm}1%\;and\;100{\pm}0.2%$ of the initial peak amplitude 60 sec after CCh application and to $38{\pm}2%,\;61{\pm}1%\;and\;100{\pm}1%$ after 120 see, respectively. The results suggest that DMSO can internally attenuate the desensitization of TRPC5 current through unknown mechanisms that remain to be elucidated.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.2
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• pp.873-876
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• 2005

This paper presents a new current transient test technique for wideband CMOS Op Amps. This technique monitors the transient power supply current and output responses of the CMOS Op Amp to automatically differentiate faulty and fault-free op amps. The wideband op amp is designed using 0.25${\mu}$m CMOS technology. We present detailed simulation results for a wideband op amp. We show that catastrophic faults in op amps can be detected and analyzed by monitoring power supply currents and output responses. This technique is inexpensive and simple.

• Nuclear Engineering and Technology
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• v.49 no.3
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• pp.466-475
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• 2017

Coolant mixing under natural circulation flow regime constitutes a key parameter that may play a role in the course of an accidental transient in a nuclear pressurized water reactor. This issue has motivated some experimental investigations carried out within the OECD/NEA PKL projects. The aim was to assess the coolant mixing phenomenon in the reactor pressure vessel downcomer and the core lower plenum under several asymmetric steady and unsteady flow conditions, and to provide experimental data for code validations. Former studies addressed the mixing phenomenon using, on the one hand, one-dimensional computational approaches with cross flows that are not fully validated under transient conditions and, on the other hand, expensive computational fluid dynamic tools that are not always justified for large-scale macroscopic phenomena. In the current framework, an unsteady coolant mixing experiment carried out in the Rossendorf coolant mixing test facility is simulated using the three-dimensional porous media capabilities of the thermal-hydraulic system CATHARE code. The current study allows highlighting the current capabilities of these codes and their suitability for reproducing the main phenomena occurring during asymmetric transient natural circulation mixing conditions.

• Journal of the Institute of Electronics and Information Engineers
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• v.53 no.2
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• pp.147-153
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• 2016

The lightning protection of information and communication facilities is very important factor to improve a reliability of the action of these equipment. Especially the transient potential rise of ground electrode being injected with the lightning current is to be a basic data of the dielectric strength for both power and communication facilities so that more accurate analysis should be required. The transient potential rise can be calculated from the ground impedance and the ground impedance is strongly dependent upon the shape of the ground electrode and the frequency-dependence of soil. The Debye's equation which is able to calculate the characteristics of dielectrics is used to analyze the frequency-dependent of soil. Also, the method to calculate the transient potential rise from the ground impedance is specified in this paper. In order to analyze the transient potential rise resulting from calculations with Debye's equation, TLM(transmission line method) and case of ${\rho}$(resistivity)-constant are simulated, respectively. The length of a horizontal ground electrode is 30 m and simulations were performed at 10, 100, $1000{\Omega}{\cdot}m$ with the standard lightning current waveform. In result, the transient potential rise of horizontal ground electrode calculating with Debye's equation is lower than it of other models.

• The Transactions of the Korean Institute of Power Electronics
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• v.22 no.2
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• pp.126-133
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• 2017

The conventional battery charger requires two separate voltage and current compensators to achieve constant current and constant-current-charging profile. This compensator configuration leads to an inevitable transient response during the mode change between the constant current and the constant voltage operation. Futhermore, a tedious and complicated design process is required to consider a widely changing battery voltage and the nonlinear electrical properties of Li-ion battery. This study proposes a single integrated voltage-current compensator of the LLC resonant converter for Li-ion battery charger applications to overcome the aforementioned drawbacks. The proposed compensator is designed to provide a smooth and reliable performance during the entire charging process while providing the reduced design efforts and seamless mode transient response. Several experimental results based on a 300 W prototype converter and its theoretical analysis are provided to verify the effectiveness of the proposed compensator.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 1999.05a
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• pp.330-334
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• 1999

This paper presents a new transient voltage blocking device (TBD) for commucation facilities with low power and high frequency bandwidth. Conventional protection devices have some problems such as low frequency bandwidth, low energy capacity and high remnant voltage. In order to improve these limitations, the new TBD, which consists of a gas tube, avalanche diodes and junction type field effect transistors (JFETs), was designed and fabricated JFETs were used as an active non-linear element and a high speed switching diode with low capacitance limits high current. Therefore the avalanche diodes with low energy capacity are protected from the high current, and the TBD has a very small input capacitance. From the performance test using surge generator, which can produce 1.2/50${\mu}\textrm{s}$ 4.2 k$V_{max}$, 8/20${\mu}\textrm{s}$ 2.1 kA$\sub$max/, it is confirmed that the proposed TBD has an excellent protection performance in tight clamping voltage and limiting current characteristics.

• Proceedings of the KIEE Conference
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• 1998.11c
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• pp.932-934
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• 1998

In an electric substation, there are many sources of surge such as switching operations or lightning strokes. A grounding system submitted to such surge current presents very different behaviour from the observed under low frequency current. Especially, it has been reported that significant overvoltage occurs at the current feed-in point, and this may cause damages to other grounded components in the substation area. This paper describes the basic mechanism of improvement of grouding performance in transient state with auxiliary grounding grids.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.91-92
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• 2008

The rating of a circuit breaker depends not only on the interrupting current but also on a transient recovery voltage (TRV). To achieve a successful interruption, the circuit breaker must withstand the TRV. A superconducting fault current limiter (SFCL) is a device that limits the fault current fast and effectively without having high impedance during normal operation of the power system. Therefore, we studied the influence of the TRV according to the application of a resistive type SFCL in distribution system. This paper analyses the influence of the TRV for various application position of the resistive SFCL. The distribution system and the resistive SFCL were modeled by using EMTP-RV (Electromagnetic Transient Program - Restructured Version)

• 한국가시화정보학회:학술대회논문집
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• 2004.12a
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• pp.111-118
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• 2004

A new micro-resolution PIV (Particle Image. Velocimetry) has been developed. To investigate transient phenomena in a microfluidic device, Dynamic micro-PIV system was realized by combining a high-speed camera and a CW(Continuous Wave) laser. The technique was applied to a micro-counter-current flow, consisting of water and butyl acetate. The velocity fields of water in the micro counter-current flow were visualized for a time resolution of 500 $\{mu}s$ and a spatial resolution of 2.2 x 2.2 $\{mu}m$. Using the Dynamic micro-PIV technique, the vortex-like motions of fluorescent particles at the water-butyl acetate interface were captured clearly

• The Bulletin of The Korean Astronomical Society
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• v.44 no.1
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• pp.71.2-71.2
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• 2019

We have developed and tested a prototype system to process transient alert messages from the currently working facilities such as Gaia and GCN notices. Our experiments with the prototype focus on developing a platform that can be used in the LSST era with about 10 million alerts per night and helping Korean community members with the automated processing environment to provide auxiliary information for every alert message. The system consists of a message broker implemented by Redis and multiple message subscribers specialized for specific scientific interests. The current implementation of the entire system allows new Korean members to adopt their own processing chains receiving the messages from our local broker. We welcome experimental ideas and opinions from the Korean community about the current message processing system. We plan to test the current system with the ZTF alerts in the near future.