• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.13 no.12
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• pp.1051-1057
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• 2000

A traveling-wave CPW(coplanar waveguide) electrode with abruptly broken input/output-taper for LiNbO$_3$optical modulator was designed and fabricated. The electrical characteristics of traveling-wave electrode on z-cut LiNbO$_3$crystal with SiO$_2$buffer layers were measured by network analyzer. To confirm the possibility of the electro-optic modulator electrode, detailed calculations of the impedance, microwave effective index and attenuation constants are presented as a function of the microwave electrode thickness, but the buffer layer thickness is fixed as 1${\mu}{\textrm}{m}$. These characteristics are discussed from the viewpoint of the device optimization and are expected to be design guides for the LiNbO$_3$modulator’s electrodes.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.05a
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• pp.1047-1051
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• 2004

Charge amplifier systems benefit from the very wide dynamic range of PE accelerometers by offering flexibility in adjusting the electrical output characteristics such as sensitivity and range. They are well suited for operation at high temperatures. Modern charge systems feature improved low noise operation, simplified digital controls, and dual mode operation for operation with charge or IEPE voltage mode sensors. high impedance circuitry is not well suited for operation in adverse field or factory environments. The resolution of a PE accelerometer may not be specified or known since noise is a system consideration determined by cable length and amplifier gain. IEPE accelerometrs operate from a constant current power source, provide a high-voltage, low-impedance, fixed mV/g output. They operate through long, ordinary, coaxial cable in adverse environments without degradation of signal quality. They have limited high temperature range. IEPE sensors are simple to operate. Both resolution and operating range are defined specifications. Cost perchannel is lower compared to PE systems since low-noise cable and charge amplifiers are not required.

• Journal of Power Electronics
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• v.16 no.2
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• pp.621-630
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• 2016

In this paper, a single current sensor technique (SCST) is proposed for single-phase full-bridge inverters. The proposed SCST measures the currents of multiple branches at the same time, and reconstructs the average inductor, capacitor, and load current in a single switching cycle. Since all of the branches' current in the LC filter and the load are obtained using the SCST, both the inductor and the capacitor current feedback schemes can be selectively applied while taking advantages of each other. This paper also analyzes both of the current feedback schemes from the view point of the closed-loop output impedance. The proposed SCST and the analysis in this paper are verified through experiments on a 3kVA single-phase uninterruptible power supply (UPS).

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.9
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• pp.1300-1305
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• 2012

A triaxial Blumlein pulse forming line has been designed to generate a pulse whose voltage is ~300 kV, pulse duration is ~5 ns, and rise time is ~500 ps. It turns out, however, that the rise time of the pulse becomes much longer than 500 ps due to parasitic inductances and capacitances existing inside the system. A peaking switch has been developed to shorten the rise time of the pulse from Blumlein pulse forming line. In the peaking switch, a wedge-shaped dielectric material (MC 901 nylon) is employed to surround the electrode on the antenna side. This shape inhibits an abrupt change of the output impedance, thereby minimizing the reflection of the output pulse. Experimental results show that the peaking switch is capable of improving the rise time of the pulse at a level of 500 ps.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.18 no.4
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• pp.481-489
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• 1993

The charge distribution is calculated to analyze the quasi-static impedance of periodic interdigital transducer taking into account the effect of infinite neighboring electrodes. The charge distribution can be represented by the element factor and array factor. The radiation conductance, susceptance and static capacitance of the input and output IDT's with arbitrary voltages are obtained by the charge distribution. The impedance of apodized IDT, is analyzed by multi-track model in which IDT is represented by the parallel connection of the uniform tracks. The calculated input and output impedances are in good agreement with the experimental results.

• Journal of the Korea Institute of Military Science and Technology
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• v.9 no.2 s.25
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• pp.136-142
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• 2006

A damped sinusoidal electromagnetic pulse generator was designed, fabricated and tested. The pulse generator consisted of an oscillator(a spark gap switch and an initially charged low impedance line) and a high impedance antenna. This generator was capable of producing damped sinusoidal pulses at closure of the spark gap switch. A Marx generator was employed to supply the Pulse generator with high voltage pulses. While the pulse generator was provided with the high voltage pulses of 200kV from the Marx generator, its output power was maximized by controlling the pressure of the gas contained in the spark gap switch. The output power of the damped sinusoidal electromagnetic pulse oscillator was 1.3GW and the amplitude of electric field radiated from the pulse generator was 4kV/m at the range of 25m.

• Journal of Power Electronics
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• v.19 no.3
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• pp.676-690
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• 2019

This paper presents a switched capacitor (SC) based bidirectional dc-dc converter topology for high voltage gain applications. The proposed converter is able to operate with multiple integral voltage conversion ratios based on user input. The architecture of a user-friendly, inductor-less multi-voltage-gain bidirectional dc-dc converter is proposed in this study. The inductor-less or magnetic-less design of the proposed converter makes it effective in higher temperature applications. Furthermore, the proposed converter has a reduced component count and lower voltage stress across its switches and capacitors when compared to existing SC converters. An output impedance analysis of the proposed converter is presented and compared with popular existing SC converters. The proposed converter is simulated in the OrCAD PSpice environment and the obtained results are presented. A 200 W hardware prototype of the proposed SC converter has been developed. Experimental results are presented to validate the efficacy of the proposed converter.

• ETRI Journal
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• v.28 no.3
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• pp.355-363
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• 2006

This paper presents a low-cost RF parameter estimation technique using a new RF built-in self-test (BIST) circuit and efficient DC measurement for 4.5 to 5.5 GHz low noise amplifiers (LNAs). The BIST circuit measures gain, noise figure, input impedance, and input return loss for an LNA. The BIST circuit is designed using $0.18\;{\mu}m$ SiGe technology. The test technique utilizes input impedance matching and output DC voltage measurements. The technique is simple and inexpensive.

• Journal of Korea Multimedia Society
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• v.21 no.6
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• pp.678-684
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• 2018

In order to broaden the indication of middle ear implant, research has been actively conducted on the reverse output method that stimulates the round window. However, it is very difficult to transmit the vibration output effectively because the indivisual anatomical difference of the round window niche is very large and also the visual field is not secured even by a skilled otolaryngologic surgeon. In this paper, we propose a new reverse stimulation method of middle ear implants that transmits energy to the inner ear by using air as a medium. This can compensate for the disadvantages of the conventional method of transmitting vibration energy and minimizes the energy transfer efficiency interference due to the combination of the excitation point and the output device. It was shown that forward and backward transfer characteristics were obtained by cadaveric experiments, and it was shown that it can overcome the acoustical impedance of high round window and transmit energy to inner ear. The receiver, which is the output device of the conventional hearing aids, can generate a constant volume velocity, so it can have a high output at a limited volume, such as a round window niche. So, suggested method can overcome the high acoustical impedance of the round window and deliver acoustic energy to the inner ear.

• The Journal of the Acoustical Society of Korea
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• v.31 no.5
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• pp.280-287
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• 2012

This paper presents a study on the experimental analysis of the impedance characteristics according to the rotational direction of the transmission beam of a cylindrical sensor array. Besides, this suggests a real time control technique of the transmitter output for the effective maximum power transmission, in order to drive efficiently the rotational transmission beam of the active sonar transmitter. The output characteristics of the transmitter and the real-time impedance variations of the sensor array are analyzed under the overload conditions. They are caused by electric and acoustic boundary conditions when the rotational transmission beam is operated. From these results, a new output control method of the transmitter is proposed to protect the transmitter and its loads. It can maximize the output power without the transmission pause even if the transient phenomena occur. The proposed technique is verified from the experiment.