• Korean Journal of Veterinary Research
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• v.31 no.1
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• pp.33-40
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• 1991

For the observations of both the membrane properties and the excitability on the unfertilized eggs of female mice, changes of the membrane resistance and the membrane potential by hyerpolarizing current stimulation were recorded. As current-voltage relation was linear over the entire range (-180mV~+60mV), membrane resistance($R_m$) was calculated from the amplitude of electrotonic potential to a given stimulus current. Also the presence of anode-break excitation was confirmed. The results were as follows; 1. There was a linear relation between the membrane resistance and resting membrane potential, the expected input resistance was 61. 4M$\Omega$(resting membrane potential was $-18.9{\pm}8.7mV$, mean${\pm}$SD, n=30). 2. Transient depolarization with overshoot was generated just after hyperpolarizing current stimulus and showed the dependency of stimulus duration. 3. Transient depolarization lasted over 30ms, amplitude of these depolarization was increased by high $Ca^{{+}{+}}$(20mM) and inhibited by $Ca^{{+}{+}}$-antagonist, $Mn^{{+}{+}}$. 4. From the above results, it was suggested that the unfertilized mouse egg showed the characteristics of the excitable cell.

• The Korean Journal of Physiology and Pharmacology
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• v.16 no.5
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• pp.343-348
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• 2012

Blocking or regulating $K^+$ channels is important for investigating neuronal functions in mammalian brains, because voltage-dependent $K^+$ channels (Kv channels) play roles to regulate membrane excitabilities for synaptic and somatic processings in neurons. Although a number of toxins and chemicals are useful to change gating properties of Kv channels, specific effects of each toxin on a particular Kv subunit have not been sufficiently demonstrated in neurons yet. In this study, we tested electro-physiologically if heteropodatoxin2 ($HpTX_2$), known as one of Kv4-specific toxins, might be effective on various $K^+$ outward currents in CA1 neurons of organotypic hippocampal slices of rats. Using a nucleated-patch technique and a pre-pulse protocol in voltage-clamp mode, total $K^+$ outward currents recorded in the soma of CA1 neurons were separated into two components, transient and sustained currents. The extracellular application of $HpTX_2$ weakly but significantly reduced transient currents. However, when $HpTX_2$ was added to internal solution, the significant reduction of amplitudes were observed in sustained currents but not in transient currents. This indicates the non-specificity of $HpTX_2$ effects on Kv4 family. Compared with the effect of cytosolic 4-AP to block transient currents, it is possible that cytosolic $HpTX_2$ is pharmacologically specific to sustained currents in CA1 neurons. These results suggest that distinctive actions of $HpTX_2$ inside and outside of neurons are very efficient to selectively reduce specific $K^+$ outward currents.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.2
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• pp.693-696
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• 2005

Parallel and cross of the electrical power and telecommunication network is become accelerated, because telecommunication equipments are constructed according to road for efficient maintenance of domestic telecommunication network. The electrical power network can generate an electrostatic induction, and is itself transmission medium from electrical transient phenomenon such as lighting. So, transient phenomenon of lightning surge is induced to telecommunication network, and then it is damaged by connecting between electrical ground of electrical power network and telecommunication network. In this study, we found that cut-off of return path current by separate distance between electrical ground of electrical power network and telecommunication network, and cut-off of electrostatic induction voltage by grounding unused leads of both terminals of the electrical and telecommunication network have good effect as the protection methods of telecommunications network from electrical transient phenomena.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.23 no.6
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• pp.78-84
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• 2009

This paper presents measurement results of transient impedance for small-sized ground electrodes in a discharge region of soil. For a realistic analysis of ionization characteristics near the ground electrode, three types of ground rod installed outdoors and high voltage impulse generator were used for injecting test current. From the analysis of response voltage and current flowing ground electrode to earth, it is verified that the ionization near the ground electrode contributes to reduction of ground impedance and limits the ground potential rise effectively in high resistivity soil. As a threshold electric field density for ionization is small in low resistivity soil, the shape of ground electrode rarely contributes to the transient impedance. And, from the experiment result with shape of ground electrode, the rod with needles is more effective to reduce the transient impedance than the plate electrode in the voltage range including with ionization regions of soil.

• Journal of Korea Society of Industrial Information Systems
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• v.24 no.2
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• pp.41-46
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• 2019

The application of series compensator in a power system affects other devices such as circuit breakers transient recovery voltage (TRV) problem. In this paper, we analyze the TRV effect on a line circuit breaker in the cases with and without thyristor-controlled series capacitor (TCSC) via simulation, and suggest an effective method to overcome the increase of TRV due to the TCSC installation. It also discusses the impact of proposed protection on metal oxide varistor (MOV). A 345 kV transmission line in Korea was selected as a study case. Grid system was modelled using PSCAD (Power Systems Computer Aided Design) / EMTDC(Electro Magnetic Transient Direct Current). The TRV was analyzed by implementing a short circuit fault along the transmission line and at the breaker terminal. The proposed protection scheme, the TRV satisfies the standard. However, the MOV energy capacity increased as the delay time increased. This result can solve the TRV problem caused by the expected transmission line fault in a practical power system.

• 한국전기화학회:학술대회논문집
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• 2001.04a
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• pp.32-32
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• 2001

• 한국전기화학회:학술대회논문집
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• 2004.04a
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• pp.56-56
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• 2004

• 한국전기화학회:학술대회논문집
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• 2000.10a
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• pp.30-30
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• 2000

• The Transactions of the Korean Institute of Electrical Engineers
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• v.43 no.2
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• pp.215-225
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• 1994

In this paper, a performance evaluation of different current regulators for induction motor drive systems fed by IGBT inverter is presented. The twoparts of current regulation are considered : current error compensation part, voltage modulation part. The characteristics of hysteresis, synchronous PI, decoupled PI, predictive, deadbeat and stage feedback controllers are analyzed and the steady-state performances and transient responses of current regulation are well compared through the simulation and experimental results.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.21 no.6
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• pp.48-54
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• 2007

This paper describes the analysis of transient phenomena on the point that a human body suffers an electrical shock. A couple of case studies were discussed by using an ATPDraw simulation tool. Two models for the case studies were constructed on the assumption that the electrical shock event takes place under water to simulate the severest condition ; the first model that the human body contacts with an energized part exposed to water ; the second model that both hands and feet simultaneously contact with the ground under water. After modeling, the transient phenomena for the models were analyzed by comparing the voltages and currents calculated at each part of the human body. As a result steep front kicks in voltage and current were observed as transient phenomena on the point that the human body contacts with the energized part exposed to water in the first model and the magnitudes of the kicks considerably increased. It was considered however, the effect of the kicks due to the commercial power source on the human body could be neglected because the product of the current through the body and the short duration is less than the safety limit. When both hands and feet simultaneously contact with the ground in the second model, the voltage generally decreased all over the body parts, while the current flowing through the chest abruptly increased. The duration of this current was very shot, as well, thus its effect on the electrical shock is considered insignificant. After all, it was confirmed through the simulation results that the electrical shock depends on the magnitude in voltage and the body impedance.