• The Journal of Korean Medicine
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• v.19 no.2
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• pp.450-467
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• 1998

To research the characteristics of ion currents induced by inhibitory and excitatory herbs of oriental medicine, we used nystatin-perforated patch clamp technique under voltage clamp condition in periaqueductal gray neuron dissociated from Sprauge-Dawley rat, 10-15 days old. The results are as follows. 1. Ion current induced by $10mg/m{\ell}$ of Bupleuri Radix was inhibited $59.50{\pm}4.29%$ by $10^{-4}M$ bicuculline(p>0.01) but inhibition of $10.75{\pm}4.77%$ by $10^{-4}M$ tubocurarine and $4.75{\pm}4.23%$ by $10^{-4}M$ verapamil had no statistical significance(p>0.05). So ion current induced by Bupleuri Radix revealed only GABA induced $Cl^-$ current, not acetylcholine and $Ca^{2+}$ current. 2. Ion current induced by $20mg/m{\ell}$ of Coptidis Rhizoma was inhibited $47.20{\pm}7.88%$ by $10^{-4}M$ bicuculline(p<0.01) but $3.20{\pm}2.33%$ inhibition by $10^{-4}M$ tubocurarine and $1.00{\pm}1.00%$ inhibition by $10^{-4}M$ verapamil had no significance(p>0.05). So ion current induced by Coptidis Rhizoma revealed only GABA induced $Cl^-$ current, not acetylcholine and $Ca^{2+}$ current. 3. Ion current induced by $20mg/m{\ell}$ of Ecliptae Herba was inhibited $55.00{\pm}4.92%$ by $10^{-4}M$ bicuculline (p<0.01), and also inhibited $15.00{\pm}4.26%$ by $10^{-4}M$ tubocurarine(p<0.05), but inhibition of $6.00{\pm}3.03%$ by $10^{-4}M$ verapamil had no significance(p>0.05). So ion current induced by Ecliptae Herba showed GABA activated $Cl^-$ current and acetylcholine activated cation current, not $Ca^{2+}$ current 4. Ion current induced by $5mg/m{\ell}$ of Liriopis Tuber was inhibited $15.20{\pm}4.57%$ by $10^{-4}M$ bicuculline<0.05) and also inhibited $14.00{\pm}3.00%$ by $10^{-4}M$ tubocurarine(p<0.05), but inhibition of $5.20{\pm}4.80%$ by $10^{-4}M$ verapamil had no significance(p>0.05). So ion current induced by Liriopis Tuber showed GABA. activated $Cl^-$ current and acetylcholine activated cation current, not $Ca^{2+}$ current. 5. Ion current induced by $5mg/m{\ell}$ of Aconiti Tuber was inhibited $97.00{\pm}1.34%$ by $10^{-4}M$ bicuculline(p<0.01), $80.00{\pm}9.83%$ by $10^{-4}M$ tubocurarine(p<0.01), and $24.00{\pm}6.18%$ by $10^{-4}M$ verapamil(p<0.05). So ion current induced by Aconiti Tuber revealed GABA activated $Cl^-$ current and acetylcholine activated cation current and $Ca^{2+}$ current. 6. Ion current induced by $10mg/m{\ell}$ of Zingiberis Rhizoma was inhibited $33.00{\pm}7.43%$ by $10^{-4}$ bicuculline(p<0.05), $10.20{\pm}1.83%$ by $10-^{-4}M$ tubocurarine(p<0.01), and $14.00{\pm}2.16%$ by $10^{-4}M$ verapamil(p<0.01) So ion current induced by Zingiberis Rhizoma revealed GABA activated $Cl^-$ current and acetylcholine activated cation outtent and $Ca^{2+}$ current. 7. Ion current induced by $10mg/m{\ell}$ of Boshniakiae Herba was inhibited $65.00{\pm}13.75%$ by $10^{-4}M$ bicuculline(p<0.05), $38.00{\pm}9.24%$ by $10^{-4}M$ tubocurarine(p<0.05), and $33.25{\pm}7.42%$ by $10^{-4}M$ verapamiHp<0.05). So ion current induced by Bpshniakiae Herba revealed GABA activated $Cl^-$ current and acetylcholine activated cation current and $Ca^{2+}$ current. These results suggest that a point of difference between inhibitory and excitatory herbs is existence of$Ca^{2+}$ current.

• Journal of the Korean Society of Safety
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• v.22 no.4
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• pp.20-25
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• 2007

Instrument transformers are a safe measurement device designed to measure high voltage and large current. A current transformer(CT) is a type of instrument transformer designed to provide a current in its secondary winding proportional to the current flowing in its primary. It is commonly used in metering and protective relaying in the electrical power industry where it facilitates the safe measurement of large current. But, care must be taken that the secondary of a current transformer is not disconnected from its load while current is flowing in the primary, as this will produce a dangerously high voltage across the open secondary, and may permanently affect the accuracy of the transformer. Especially, industrial disaster such as an electric shock and/or a burn accident occurs occasionally by disregard of warning or attention. In this paper, we developed the detector for open of current transformer secondary terminal, and which was tested by the Korea Electrotechnology Research Institute. Test results show that Current Transformer secondary Open Detector(CTOD) interrupted within one second electronically when the 2nd terminal of current transformer opened.

• The Journal of the Korea institute of electronic communication sciences
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• v.8 no.3
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• pp.447-452
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• 2013

In this paper, the leakage current detection and auto shut-off module for a concent has been developed. Existing leakage current detection modules are detecting resistive leakage current, using a resistive leakage current detection chip but the proposed leakage current detection module separates and detects resistive leakage current in the synthesis leakage current by only programming in a power processor MCU(MSP430). The module implemented by proposed method has early detection and auto shut-off feature at more than resistive leakage current 5mA, and has the advantage of easily adjusting resistive leakage current less or more than 5mA, because of resistive leakage current detection function being implemented by a program in MCU.

• 한국신재생에너지학회:학술대회논문집
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• 2010.06a
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• pp.235.1-235.1
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• 2010

Two ocean current power parks are suggested in the front and back of the Garyuk draining sluices of Saemankeum in Korea. They are characterized by installing a plurality of ocean current turbine generators which are arranged in five rows respectively in the land-side ocean current power park behind the Garyuk draining sluices and in the sea-side ocean current power park before the Garyuk draining sluices, generating electricity using the ocean current flowing through the Garyuk draining sluices in the ebbs and tides of Yellow sea. The potential energy of tidal difference of 2.611m at neap in Saemankeum can be converted into the kinetic energy of high speed ocean current via the Garyuk draining sluices which makes it possible to run the ocean current power parks on a large scale. The total facility capacity of two ocean current power parks that consist of 240 ocean current turbine generators with 4m diameter of turbine blades is about 134MW, and the expected total annual power output is about 586GWh.

• The Transactions of the Korean Institute of Power Electronics
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• v.11 no.5
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• pp.426-430
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• 2006

This paper deals with a novel utilization method of the predicted current in the high performance PI current controller with a control time delay. The inevitable error of the predicted current in the linear servo drive using a permanent magnet linear synchronous motor is analyzed and a modified cross-coupling decoupling synchronous frame PI current controller is proposed in order to improve the current control response under both the control time delay and the inevitable current prediction error. Simulation and experimental results show that the proposed current controller has an improved current control performance under both the control time delay and the inevitable current prediction error in the servo drive system.

• Journal of the korean society of oceanography
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• v.32 no.1
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• pp.1-7
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• 1997

Surface current fields in the eastern East China Sea (ECS) were constructed by analyzing trajectories of 58 satellite-tracked surface drifters released during 1991-1996. Composite trajectories and 20-minute-by-20-minute box-averaged current vectors show that the basic current pattern composes of: the Kuroshio main stream, which turns eastward toward the Tokara Strait; a northward branch current of the Kuroshio on the ECS outer shelf deeper than 100 m; and an anticyclonic circulation in the northern Okinawa Trough west of Kyushu. The northward branch current sharply changes its direction to the northeast when it crosses a line connecting Cheju Island, Korea and Goto Islands, Japan. The basic pattern of current field changes slightly from winter to summer, and the main axis of the Tsushima Current in the Korea Strait is found to shift seasonally. The drifter experiment does not support the claim that the Yellow Sea Warm Current is separated from the northward branch current on the outer shelf southeast of Cheju Island. We suggest that the use of the term 'Tsushima Current' be limited to the northeast channel flow in the Korea Strait. The new term 'Kuroshio Branch Current' is suggested for the northward branch current on the outer shelf south of Cheju-do, which is separated from the Kuroshio.

• Journal of Power Electronics
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• v.18 no.2
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• pp.615-626
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• 2018

To ensure a DC current path and avoid large voltage overshoot of the DC-link inductor, alternating PWM pulses in the current-source rectifier should be supplemented by overlap time, which generates an overlap current and causes input current distortion. In this study, the influence of overlap time is illustrated by comparing the AC-side current before and after overlap time is added. The overlap current distribution caused by overlap time is discussed under different modulation carriers, including triangle carrier, positive-going carrier, and negative-going carrier. The quantitative relationship between the extra harmonics of the AC-side current and overlap time is based on the Fourier analysis. Based on the commutation analysis, a new carrier modulation scheme that can restrain overlap current is proposed. A 3 kW prototype is established to verify the effectiveness of the influence of overlap time and the proposed restraining modulation scheme.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.24 no.1
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• pp.47-51
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• 2011

The superconducting fault current limiter (SFCL) with a peak current limiting function according to the initial fault current with the different amplitudes was suggested. The proposed SFCL, which consists of two limiting components, causes only the first superconducting element among two limiting components to be quenched in case that the initial fault current with the lower peak amplitude happens. On the other hand, the initial fault current with the higher peak amplitude makes both the superconducting elements of two limiting components to be quenched, which contributes to the peak current limiting function of the SFCL. To confirm the fault current limiting operation of the proposed SFCL, the short-circuit tests of the SFCL according to the fault angle were carried out and its effective fault current limiting operations could be discussed.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.41 no.7
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• pp.89-96
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• 2004

High-linearity voltage-controlled current sources (VCCSs) circuits for wide voltage-controlled oscillator and automatic gain control are proposed. The VCCS consists of emitter follower for voltage input, two common-base amplifier which their emitter connected for current output, and current mirror which connected the two amplifier for large output current. The VCCS used only five transistors and a resistor without an extra bias circuit. Simulation results show that the VCCS has current output range from 0㎃ to 300㎃ over the control voltage range from 1V to 4.8V at supply voltage 5V. The linearity error of output current has less than 1.4% over the current range from 0A to 300㎃.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.5
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• pp.761-766
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• 2008

This paper describes a compensation algorithm for a measurement voltage transformer (VT) based on the hysteresis characteristics of the core. The error of the VT is caused by the voltages across the primary and secondary windings. The latter depends on the secondary current whilst the former depends on the primary current, i.e. the sum of the exciting current and the secondary current. The proposed algorithm calculates the voltages across the primary and secondary windings and add them to the measured secondary voltage for compensation. To do this, the primary and secondary currents should be estimated. The secondary current is obtained directly from the secondary voltage and used to calculate the voltage across the secondary winding. For the primary current, in this paper, the exciting current is decomposed into the two currents, i.e. the core-loss current and the magnetizing current. The core-loss current is obtained by dividing the primary induced voltage by the core-loss resistance. The magnetizing current is obtained by inserting the flux into the flux-magnetizing current curve. The calculated voltages across the primary and secondary windings are added to the measured secondary current for compensation. The proposed compensation algorithm improves the error of the VT significantly.