• Journal of the Korean Institute of Telematics and Electronics
• /
• v.11 no.4
• /
• pp.30-38
• /
• 1974

This paper presents a method, which finds the current distribution and input impedance at the arbitrary feeding point of bended linear antenna in arbitrary shape in accordance with the MOMENT method. Practically the method of analysis is applied to the sinusoidal-shaped antenna, and the results of the calculation of current distribution and input impedance consist with the theoretical values. The method can be extensively used for the analysis of any of type antenna problems.

• Proceedings of the KIPE Conference
• /
• 2001.12a
• /
• pp.171-174
• /
• 2001

This paper proposes a nonlinear impedance circuit composed by diodes and inductors or capacitors. This circuit needs no control circuits and switches, and the impedance .value is changed by the polarity of current or voltage. and this paper presents one of these applications to improve the input current of capacitor input diode rectifiers. The rectifier using the nonlinear impedance circuit id constructed with four diodes and four capacitors in addition to the conventional rectifiers, that is, it has eight diodes and five capacitors, including a DC link capacitor. It makes harmonic components of the input current reduce and the power factor improve. A circuit design method is shown by experimentation and confirmed simulation. It explained that compared conventional pulse width modulated (PWM) inverter with half pulse-width modulated (HPWM) inverter. Proposed HPWM inverter eliminated dead-time by lowering switching loss and holding over-shooting.

• Proceedings of the KIEE Conference
• /
• 2001.07b
• /
• pp.1044-1048
• /
• 2001

This paper proposes a nonlinear impedance circuit composed by diodes and inductors or capacitors. This circuit needs no control circuits and switches, and the impedance value is changed by the polarity of current or voltage. This paper presents one of these applications to improve the input current of capacitor input diode rectifiers. The rectifier using the nonlinear impedance circuit id constructed with four diodes and four capacitors in addition to the conventional rectifiers, that is, it has eight diodes and five capacitors, including a DC link capacitor. It makes harmonic components of the input current reduce and the power factor improve. A circuit design method is shown by experimentation and confirmed simulation. It explained that compared conventional pulse-width modulated (PWM)inverter with half pulse-width modulated (HPWM) inverter proposed HPWM inverter eliminated dead-time by lowering switching loss and holding over-shooting.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2015.05a
• /
• pp.480-481
• /
• 2015

General microstrip patch antenna has small bandwidth. If corner of a patch antenna is properly cutted to be triangular shape, then input impedance of patch antenna should be varied. Using this characteristic wideband patch antenna can be implemented. In this paper, wideband microstrip patch antenna operating in 2.4GHz ISM band is investigated through tracking variation of input impedance corresponding to cutting shape of patch antenna.

• Proceedings of the IEEK Conference
• /
• 2000.11b
• /
• pp.245-248
• /
• 2000

In this paper, we present a high-performance SiGe HBT's RF input impedance parameter extraction method. The SiGe HBT has emitter width of 0.5${\mu}{\textrm}{m}$ and length of 6${\mu}{\textrm}{m}$. S-parameter has been measured with the collector current of 1~3㎃ using on-wafer RF measuring system . The pre-calculation method was used in order to overcome the local minimum problem. This method enabled us to extract a RF(1~10㎓) input impedance parameter.

• JSTS:Journal of Semiconductor Technology and Science
• /
• v.13 no.6
• /
• pp.569-575
• /
• 2013

An improved non-quasi-static gate-source impedance model including a parallel RC block for short-channel MOSFETs is developed to simulate RF MOSFET input characteristics accurately in the wide range of high frequency. The non-quasi-static model parameters are accurately determined using the physical input equivalent circuit. This improved model results in much better agreements between the measured and modelled input impedance than a simple one with a non-quasi-static resistance up to 40GHz, verifying its accuracy.

• Proceedings of the IEEK Conference
• /
• 2001.06e
• /
• pp.241-244
• /
• 2001

This paper proposes a nonlinear impedance circuit composed by diodes and inductors or capacitors. This circuit needs no control circuits and switches, and the impedance value is changed by the polarity of current or voltage, This paper presents one of these applications to improve the input current of capacitor input diode rectifiers. The rectifier using the nonlinear impedance circuit id constructed with four diodes and four capacitors in addition to the conventional rectifiers, that is it has eight diodes and five capacitors, including a DC link capacitor. It makes harmonic components of the input current reduce and the power factor improve. A circuit design method is shown by experimentation and confirmed simulation. It explained that compared conventional pulse-width modulated (PWM)inverter with half pulse-width modulated (HPWM) inverter. Proposed HPWM inverter eliminated dead-time by lowering switching loss and holding over-shooting.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.23 no.10
• /
• pp.920-927
• /
• 2013

The requirement of acoustic performance about underwater acoustic material which is used in underwater environment more increases. Underwater acoustic material was made by viscoelastic material such as a rubber and a polyurethane etc. In order to increase an acoustic performance, several kinds of inclusions were added to viscoelastic material. In this paper, acoustic modelling and analysis techniques were introduced and the acoustic characteristics of underwater acoustic material were studied. Echo reduction and transmission loss were calculated with volume fraction of inclusion in the material. Also the characteristic impedance and the input impedance of underwater acoustic material were obtained and effects on the echo reduction and transmission loss of material were discussed.

• Progress in Superconductivity and Cryogenics
• /
• v.15 no.3
• /
• pp.35-39
• /
• 2013

In this paper, we present test results of developed 100 W class linear compressor for Stirling-type pulse tube refrigerator. The fabricated linear compressor has dual-opposed configuration, free piston and moving magnet type linear motor. Power transfer, efficiency and required pressure waveform are predicted with designed and measured specifications. In experiments, room temperature test with flow impedance is conducted to evaluate performance of developed linear compressor. Flow impedance is loaded to compressor with metering valve for flow resistance, inertance tube for flow inertance and buffer volumes for flow compliance. Several operating parameters such as input voltage, current, piston displacement and pressure wave are measured for various operating frequency and fixed input current level. Behaviors of dynamics and performance of linear compressor as varying flow impedance are discussed with measured experimental results. The developed linear compressor shows 124 W of input power, 86 % of motor efficiency and 60 % of compressor efficiency at its resonant operating condition.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.24 no.7
• /
• pp.537-548
• /
• 2014

In this paper, horn loudspeaker modeling was suggested, investigated and verified through comparison of test results and simulation ones based on input electrical impedance curves and acoustic sensitivity ones. First, Thiele Small parameters of horn driver were identified by using pseudo loudspeaker model concept and verified in case of both closed and open horndriver. Second, cone-shaped horn models were investigated and compared with input acoustic impedance curves for real horn(cone angle $6.6^{\circ}$) and short horn(cone angle $27.9^{\circ}$). It showed that Leach model for cone horn was well described to test results, which were electrical impedance and acoustic sensitivity, compared to Lemaitre one. To represent horn system model good approximation in wide frequency range, mass correction filter and lowpass filter were adopted and consequently showed good fitted to test results.