• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1997.04a
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• pp.198-201
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• 1997

The new system for identification of organic vapours and analysis method of mechanism between organic vapours and sensitive materials were attempted using the resonant resistance and resonant frequency of Quartz Crystal Analyzer (Q. C. A.). The resonant resistance shift means rheological changes in sensitive LB films occurred by the adsorption of organic vapours, while the resonant frequency shift represent the mass of organic vapour loaded in or on the sensitive LB films. It is thought that we can obtain more accurate response mechanism of organic vapour using the resonant frequency and resonant resistance diagram. The polymeric sensitive material were quantitively depositied using the LB method. In the experimental results, the adsorption behavior of organic vapour response can be decided by two type ; surface adsorption and penetration into sensitive material. Organic vapours had different positions in the Frequency-Resistance (F-R) diagram as to the kinds and concentrations of organic vapours. Thus F-R diagram can be applied to the development of one channel gas sensing system using the Quartz Crystal Analyzer.

• The Transactions of the Korean Institute of Power Electronics
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• v.23 no.1
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• pp.24-31
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• 2018

An induction heating (IH) resonant converter, as well as its coil design method, is proposed in this study to improve the heat capability of low- and high-resistance IH vessels. Conventional IH resonant converters have been designed only for heating high-resistance containers designed for IH application. Thus, the primary current in the resonant tank becomes extremely high to transfer the rated power when the converter heats the low-resistance vessel. As a result, the rated power cannot be transferred due to overcurrent flows against the rated switch current. Hence, the optimal number of coil turns and proper operating frequency to heat high- and low-resistance vessels are proposed in this study by analyzing an IH load model. Simulation and experimental results using a 2.4 kW prototype resonant converter and its IH coil validate the proposed design.

• Journal of Korean Port Research
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• v.12 no.2
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• pp.323-328
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• 1998

A quartz crystal analyzer is utilized to monitor the corrosion process of an aluminum surface of a quartz crystal for marine sensor by sea water. A quartz crystal having 2000 $\AA$ of aluminum layer is installed in a specially designed cell and is in contact with sea water imitated electrolyte solution. While a constant potential is applied to the cell, the resonant frequency and resonant resistance are simultaneously measured using the quartz crystal analyzer. In addition, surface topographs are taken with an atomic force microscope(AFM) and the element analysis of the surface is conducted using an energy dispersive X-ray spectrometer(EDX). The simultaneous measurement of resonant frequency and resonant resistance during the corrosion process explains the change of surface structure caused by the corrosion. The variation of resonant frequency addresses the amount surface metal dissolution. As a conclusion, it is found that a simple measurement using the quartz crystal analyzer can replace the complex monitoring employing large equipments in the investigation of a corrosion process of sensor surface.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 1998.10a
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• pp.183-188
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• 1998

A quartz crystal analyzer is utilized to monitor the cmsion process of an aluminum surface of a quartz crystal by sea water. A quartz crystal having 2000${\AA}$ of aluminum layer is installed in a spedally designed cell and is in contact with an electrolyte solution. While a constant potential is applied to the cell, the resonant frequency and resonant resistance are simultaneously measured using the quartz crystal analyzer. In addition, surface topographs are taken with an atomic force microscope(AFM) and the element analysis of the surface is conducted using an energy dispersive X-ray spectrornetedEDX). The simultaneous measurement of resonant frequency and resonant resistance during the corrosion process explains the change of surface structure caused by the corrosion. The variation of resonant frequency addresses the amount surface metal dissolution. As a conclusion, it is found that a simple measurement using the quartz crystal analyzer can replace the complex monitoring employing large equipments in the investigation of a corrosion process of metal surface.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.33A no.10
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• pp.139-143
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• 1996

We report on the static and dynamic characteristics of optically modulated resonant tunneling diode oscillator (RTDO) formed in double-barrier quantum-well structure. Under the illumination of Ti:Sapphire laser, the dc current-voltage (I-V) curves of RTDO shifted towared lower voltages. This characteristic was found to odify the series resistance, negtive differential resistance, capacitance, and the inductance of the RTDO. As a result, the resonant frequency of TRDO centered at 5.302 GHz was found to decrease about 20 MHz under the laser illumination. At a constnat bias voltage, the oscillation frequency decreased linearly as the laser power was increased.

• Journal of Korean Port Research
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• v.14 no.4
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• pp.475-479
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• 2000

A possibility of the implementation of a quartz crystal sensor to the determination of chemical oxygen demand is examined by checking the electrochemical behavior of the sensor in a glucose solution. Since the surface of a quartz crystal has to be oxidized, a relatively active metal is coated on the surface of a usual 9 MHz AT-cut crystal. The electrochemical behavior is investigated by measuring the changes of current, resonant frequency and resonant resistance while a constant potential is applied. The crystal is installed in a specially designed container, and a quartz crystal analyzer is utilized to measure the frequency and resistance simultaneously. The variations of the measurements are examined at different concentrations of glucose solution, and a proper relation between the concentrations of glucose solution, and a proper relation between the concentration and the measurements is analyzed. As a result, it is found that a linear relation between the concentration of less than 900 ppm and the peak current when a constant potential of -180 mV (SSCE) is applied. The relation can be utilized for the determination of glucose concentration in sea water, and considering a direct relation between gluose concentration and chemical oxygen demand tells a possibility of the measurement of chemical oxygen demand using quartz crystal oscillators.

• The Transactions of the Korean Institute of Power Electronics
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• v.22 no.6
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• pp.504-509
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• 2017

This paper proposes a procedure for designing a resonant network for induction cookers that enables the induction heating of magnetic and non-magnetic vessels. In order to design such network, the range of operating frequency must be determined according to the material of the vessels by measuring several parameters, such as equivalent resistance and inductance, which are reflected in the working coil of the vessels. Through this process, the capacitance of the resonant capacitor is determined. The PSIM simulation and experiment results verify the feasibility of the proposed design and the heating performance of the designed resonant network.

• Proceedings of the KIEE Conference
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• 1996.11a
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• pp.261-263
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• 1996

The study on the development of one-channel gas sensor using the quartz crystal analyzer were attempted. The adsorption and desorption behavior of organic gases were investigated using the resonant frequency and resistance method of quartz crystal. The sensitive materials were deposited on the quartz crystal analyzer(QCA) by using Langmuir-Blodgett method. To investigate the response characteristics of organic vapours and response mechanism, resonant frequency-resonant resistance (F-R) diagram was used. In our experimental results, the response mechanism between sensitive LB film and organic vapours was obtained using F-R diagram. And the position of each organic vapour were different as to the kind and injection amount. Thus F-R diagram can be applied to one-channel gas sensor using the QCA and useful to analyze the response mechanism between organic vspours and sensitive LB films.

• Proceedings of the KIEE Conference
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• 1993.11a
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• pp.129-131
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• 1993

Power conversion system of high performance requires high switching frequency power converter. In order to minimize commutation stress and switching losses, in this paper, AC-DC converter is embedded a partial resonant DC-Link circuit with the object of ZVCS(zero voltage switching and zero current switching). The partial resonant occurs just before converter switch operates. Thus, VA ratings of the elements and their dissipations due to effective series resistance (ESR) are very low. Some simulative results on computer are included to confirm the validity of the analytical results.

• JSTS:Journal of Semiconductor Technology and Science
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• v.4 no.1
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• pp.27-31
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• 2004

Models and simulations of gate tunneling current for thinoxide MOSFETs and Double-Gate SOIs are discussed. A guideline in design of leaky MOS capacitors is proposed and resonant gate tunneling current in DG SOI simulated based on quantum-mechanicalmodels. Gate tunneling current in fully-depleted, double-gate SOI MOSFETs is characterized based on quantum-mechanical principles. The simulated $I_G-V_G$ of double-gate SOI has negative differential resistance like that of the resonant tunnel diodes.