• ETRI Journal
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• v.30 no.1
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• pp.33-46
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• 2008

This paper presents the experimental results of a low-power low-cost RF transceiver for the 915 MHz band IEEE 802.15.4b standard. Low power and low cost are achieved by optimizing the transceiver architecture and circuit design techniques. The proposed transceiver shares the analog baseband section for both receive and transmit modes to reduce the silicon area. The RF transceiver consumes 11.2 mA in receive mode and 22.5 mA in transmit mode under a supply voltage of 1.8 V, in which 5 mA of quadrature voltage controlled oscillator is included. The proposed transceiver is implemented in a 0.18 ${\mu}m$ CMOS process and occupies 10 $mm^2$ of silicon area.

• Proceedings of the KIPE Conference
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• 2003.07b
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• pp.896-899
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• 2003

The electric railway has been widely used as a transportation all over the world. It also was opened in 1973 in korea and it has been steadily proceeded in making electric railway network for a big city and building Keongbu high speed , electric railway. That's why the system of electric railway is able to solve the environmental pollution and operate the useful energy in environmental ways, it helps to increase the ability of transportation and to decrease the cost. Because of the advantage of making the economic situation better, the system of electric railway is trying to do their best in developing technique of electric railway. Because of the increasing of transportation and the high speed operation, cars with regenerative braking system was adapted. Therefore, unbalanced voltage and current of three phase system and the drop and rise of voltage of feeding circuit is expected. Now that building the substation, newly spends lots of costs and time, it is a very difficult situation to solve the problem. We can guess that electric railway line can't receive power from the power system of bigger size in building newly electric railway. In this paper, it was proved that series voltage compensator was suitable as a solution according to voltage drop and voltage fluctuating through computer simulation.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.3
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• pp.239-243
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• 2003

In this paper, an angle diversity wireless optical detector is realized that can receive the optical signal at an angle from 0 to 360 degrees. Eight photodiodes constitute an angle diversity receiver, and in order to reduce the voltage variation with the incident angle, the optical detector is stabilized with a digital potentiometer. In a stabilized state, the voltage variation is kept within 1/10 of maximum voltage. This configuration is very useful in constructing an omni-directional receiver in a wireless optical interconnection.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.09a
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• pp.19-22
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• 2001

For stabilization and improving power factor in the power lines, various Static Var Compensators(SVC) have been considered to be installed and partly applicated already. With all these merits of the SVC, it stil has demerits, principally evoking harmonic problems. So far, many harmonic reduction type inverters have been used in various parts. In this paper, the reactive power is controlled by amplitude of the output voltage. This paper propose that the multiple voltage source inverter have controllable power factor made by load vary at receive-stage as lagging and leakage control. The theoretical analysis on this system was confirmed through the computer simulation and the experiments.

• Physical Therapy Korea
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• v.1 no.1
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• pp.61-66
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• 1994

The purpose of this study was to investigate the effect of a single treatment o voltage pulsed current (HVPC) on edema reduction. Hind limbs of 23 anesthetized were injured by dropping a 400 g weight onto the plantar aspects of the feet. On limb of each frog was randomly selected to receive 30 minutes of continuous, 12 cathodal HVPC at voltages 10 % less than motor threshold levels. Limb volumes measured by water displacement before trauma and at predetermined intervals hours posttrauma. Sources of significant differences were determined by t-test HVPC significantly (p<0.05) reduced edema formation. We hypothesize that HVP also be effective in controlling edema formation after impact injuries in humans.

• Proceedings of the KIEE Conference
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• 1995.07a
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• pp.403-406
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• 1995

In general, the reactive power is controlled by amplitude of the output voltage. This paper propose that the multiple voltage source inverter have controllable power factor made by load vary at receive-stage as lagging and leakage control.

• Journal of the Korean Society for Railway
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• v.13 no.6
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• pp.565-569
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• 2010

Sleepers perform bearing rails and are underneath rails. Therefore, the current and voltage of rails are related to the resistance of sleepers. In case that the resistance of sleepers are low, operation problems of relays in tr ack circuits are occur because of flowing leakage current through sleepers. So the condition that the track circuit is always occupied by a train is kept. Currently, the creosote has been used in wood sleepers due to prevention against putrefaction. After a long time, the material is changeable to the chemistry material bases on carbon dioxide or carbon. So, the insulation resistance of wood sleepers is lower than the initial insulation resistance. In case of effecting wood sleepers as conductors, amplitude of the current and voltage on rails is decreased. This phenomenon causes that a train does not receive signals. In this paper, four-network model on the track circuit including the insulation resistance of sleepers is suggested. Also, the standard value of the resistance in straight section is proposed in the wood sleeper.

• The Transactions of the Korean Institute of Power Electronics
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• v.28 no.1
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• pp.22-29
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• 2023

A grid-connected inverter can be used in grid-connected or stand-alone modes. Generally, a grid-connected inverter operates in a grid-connected mode, but the inverter operates in stand-alone mode if grid faults occur. In the stand-alone mode, the grid-connected inverter must supply electric power to a critical load that needs to receive stable power even though grid faults occur. Generally, three-phase loads are used as critical loads, but a single phase is configured in some cases. In these conditions, the critical load is required to unbalance the load power consumption, which makes the three-phase load voltage unbalancd. This unbalanced voltage problem can cause fatal problems to the three-phase critical loads, and thus must be addressed. Hence, this paper proposes an algorithm to solve this unbalanced voltage problem by the individual phase current control. The proposed method is verified using Psim simulation and experiments.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.35D no.7
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• pp.40-47
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• 1998

This paper presents the physiological signal processing CMOS one chip for transmitting human bodys small electrical signals such as electrocardiogram(EKG) or electromyogram(EMG) and the external system for receiving signals was implemented by the commercial ICs. For simultaneous four-subject four-channel telemetry, a new enfored synchronization techniqeu using infrared bi-directional communication has been proposed. The telemeter IC with the size of 5.1*5.1mm$^{2}$ has the following functions: receiving of command signal, initialization of internal state of all functional blocks, decoding of subject-selection signal, time multiplexing of 4-channel modulated physiological signals, transmitting of telemetry signal to external system and auto power down control. The newly designed synchronized oscillator with low supply voltage dependence in the telemeter IC operates at a supply voltage from 4.6~6.0V and the nonlinearity error of PIM modulator was less than 1.2%F.S(full scale). The power saving block operates at the period of 2.5ms even if the telemetry IC does not receive command signal from external system for a constant time.

• Progress in Superconductivity
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• v.4 no.1
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• pp.64-67
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• 2002

The attenuation of millimeter waves (70-100 ㎓) propagating along Josephson Junction stripline had been measured by pattern recognition near gap voltage and proximity current bump. Test series arrays of 2000, 3000, and 4000 Josephson junctions with the area of $12\mu\textrm{m}$$\times$ $38\mu\textrm{m}$ had two sub-arrays with 50 Junctions at both ends. The arrays were fabricated with and without applying a plasma nitridation process to Nb ground plane. The effects of a nitridationprocess measured by the pattern recognition near gap voltage and proximity current bump were about 1.3-1.7 ㏈ and 1.6-1.8 ㏈, respectively. This means that the last sub-arrays with a nitridation process receive 26-34% more power than those without a nitridation process.