• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.5
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• pp.61-66
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• 2013

In this paper, temperature dependence of matching characteristics of $Si_3N_4$ MIM capacitor was analyzed in depth. The matching characteristics becomes worse as the temperature increases. That is, the matching coefficient of $Si_3N_4$ MIM capacitor at $25^{\circ}C$, $75^{\circ}C$, and $125^{\circ}C$ was 0.5870, 0.6151, and $0.7861%{\mu}m$, respectively. This phenomena is believed to be due to the reduction of the carrier mobility and the increase of the charge concentration of the inner capacitor at greater temperature. Therefore, the analysis of the matching characteristics of $Si_3N_4$ MIM capacitors at high temperatures is essential for application to analog and SoC (System on Chip) circuit.

• Journal of the Korean Electrochemical Society
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• v.1 no.1
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• pp.40-44
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• 1998

The LAPS device of fast response and high sensitivity, based on electrochemical potential difference, and its system were fabricated for the precise measurement of pH changes and its characteristic were investigated. The electrostatic variation characteristics of LAPS according to the pH changes and parameters in the device were verified through a simulation using LAPS equivalent circuit model. The LAPS device and its system were fabricated on the basis of the result of simulation. The fabricated LAPS system showed linear sensitivity (about 56 mV/pH within the range of pH 2 to pH 11. In order to overcome the defect of general urea sensor (especially slow response time), urease immobilized nitrocellulose membrane was attached on the LAPS and resulted in the very fast response time, 0.29 mV/sec, 0.86 mV/sec at urea concentration of $50{\mu}g/ml,\; 500{\mu}g/ml$, respectively. And also in order to measure the uranyl ion, the uranyl ion selective sensing membrane with calix[6]arene derivative was used and its sensitivity was 25mV/concentration decade in the wide uranyl ion concentration range of $10^{-11}M\;to\;10^{-4}M$.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.12 no.4
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• pp.651-658
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• 2001

A novel multi-section power divider configuration is proposed to obtain wide-band frequency performance up to microwave frequency region. Design procedures for the proposed microwave broadband power divider are composed of a planar multi-section three-ports hybrid and a waveguide transformer design procedures. The multi-section power divider is based on design theory of the optimum quarter-wave transformer. Furthermore, in order to obtain the broadband isolation performance between the two adjacent output ports, the odd mode equivalent circuit should be matched by using the lossy element such as resistor. The derived design formula for calculating these odd mode matching elements is based on the singly terminated filter design theory. The waveguide transformer section is designed to suppress the propagation of the higher order modes such as waveguide modes due to employing the metallic electric wall. Thus, each section of the designed waveguide transformer should be operated with evanescent mode over the whole design frequency band of the proposed microwave broadband power divider. This paper presents several simulations and experimental results of multi-section power divider to show validity of the proposed microwave broadband power divider configuration. Simulation and experiment show excellent performance of multi section power divider.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.8 no.1
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• pp.13-21
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• 1997

In this paper, the oscillator type active antenna used as an element of active phased array antenna is designed and fabricated using slot coupling. The radiating element and active circuit are fabricated on each layer respectively and coupled electromagnetically through slot on the ground plane. This structure can solve the problems such as narrow bandwidth of microstrip antenna, spurious radiation by active circuits, and spaces for integration of the feeding circuits which are caused by integrating antennas with oscillator circuits in the same layer. The active antenna in this paper, the oscillation frequency can be tuned linearly by controlling the drain bias voltage of FET. The frequency tuning range is between 12.37 GHz to 12.65 GHz when bias voltage is varied from 3V to 9V, thus frequency tuning bandwidth is 280 MHz (2.24%). The output power of antenna is uniform within 5dB over frequency tuning range. Therefore this active antenna can be used as an element of linear or planar active phased array antennas.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.27 no.2
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• pp.170-175
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• 2016

In order to transmit baseband signals through frequency dividing devices, we studied the transfer function of the device in the term of the baseband signal distortion. From the analysis, it is shown that the magnitude of the envelope signal is related to the mixer gain and the insertion loss of the low pass filter whilst the phase is the additional function with the 1/2 of the phase delay. For the purpose of the verification of the study, we designed a dynamic frequency divider at 1,400 MHz. The operating frequency range of the device is closely related to the conversion gain of mixers and the amplitude of input signal, and becomes wide as the conversion gain of mixers increases. The designed frequency divider operates between 0.9 GHz and 3.2 GHz, for -14.5 dBm input power. The circuit shows 20 mW power dissipation at $V_{DD}=2.5V$, and the simulation result shows that an amplitude modulated signal at 1,400 MHz with the modulation index of 0.9 was successfully downconverted to 700 MHz.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.23 no.9
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• pp.1087-1093
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• 2012

In this paper, we implemented a HF-band magnetic-field communication system consisting of an amplitude shift keying(ASK) transmitter, a pair of loop antennas, and an ASK receiver. Especially, we suggested a new ASK transmitter architecture, where a drain bias of class E amplifier is switched alternatively between two voltage levels with respect to input data. A maximum 5 W class E amplifier was designed using a low cost IRF510 power MOSFET at the frequency of 6.78 MHz. A measured sensitivity of the designed ASK receiver is -78 dBm, which consists of a log amplifier, a filter, and a comparator. Maximum communication range of magnetic-wave communication system with loop antennas was calculated using magnetic field equations in both near-field and far-field ranges. Also, in order to verify the calculated values, an indoor propagation loss was measured using a pair of loop antennas whose dimensions are $30{\times}30cm$. Maximum operating range is estimated about 35 m in case of transmitter's output power of 1 W and receiver sensitivity of -70 dBm, respectively. Finally, the communication field test using the designed ASK transmitter and receiver was successfully done at the distance of 5 m.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.24 no.9
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• pp.936-943
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• 2013

This work presents the design and measured results of the single channel automotive radar system for 76.5~77 GHz long range FMCW radar applications. The transmitter uses a commercial GaAs monolithic microwave integrated circuit(MMIC) and the receiver uses the down converter designed using 65 nm CMOS process. The output power of the transmitter is 10 dBm. The down converter chip can operate at low LO power as -8 dBm which is easily supplied from the transmitter output using a coupled line coupler. All MMICs are mounted on an aluminum jig which embeds the WR-10 waveguide. A microstrip to waveguide transition is designed to feed the embedded waveguide and finally high gain horn antennas. The overall size of the fabricated radar system is $80mm{\times}61mm{\times}21mm$. The radar system achieved an output power of 10 dBm, phase noise of -94 dBc/Hz at 1 MHz offset and a conversion gain of 12 dB.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.28 no.6
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• pp.470-477
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• 2017

As a method of the transmission efficiency improvement of an aperture smaller than the wavelength, we modified the conventional H-shaped resonant aperture to lower the resonance frequency of resonant aperture, and the transmission efficiency of resonant aperture was improved more than the conventional aperture. The maximum transmission cross section(TCS) calculated using the equivalent circuit tends to be almost equal to the maximum TCS from the small resonant aperture modified to improve the transmission efficiency. The transmission characteristics of resonant apertures can be quantified as the TCS, and the transmission efficiency of that can be compared. The modified resonant aperture has a maximum TCS increased by about 2.87 times from $846mm^2$ to $2,431mm^2$ compared to the H-shaped aperture, and the resonant frequency decreased from 5.06 GHz to 2.92 GHz, and the length-to-wavelength ratio of the aperture was reduced from 0.178 to 0.103.

• Journal of the Korean Home Economics Association
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• v.40 no.12
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• pp.85-108
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• 2002

The objectives of this study were to investigate the trend of the attitude and the behavior about consumer's internet premium advertisement and its application and the factors which influence on the attitude and the behavior about consumer's premium advertisement and its application; the demographic variables, internet communication-environment variables and variables in relation to consumer's premium advertisement application. For these purpose, the data collected two way: internet survey and questionnaire survey. The data used in this study included people who have looked an internet Premium Advertisement more than once during internet use. Major findings were as following: (1) The attitude of internet premium advertisement and its application could be described as the mean 34.16 md 24.61 separately(3.11 and 2.73 point on 5.00 points scale). The behavior of application about internet premium advertisement was measured as a behavior of application whether or not; application 18.7% and unapplication 81.3%. (2) The attitude of application about internet premium advertisement was significantly different according to age, joining frequency on internet, past experience of winning a premium, purchasing information search, interesting connection on the internet, the risk about the money loss and negative evaluation of other persons, the economical values of premiums, winning possibility, and preferable premiums. The behavior of application about internet premium advertisement, the behavior of application whether or not was significantly different according to sex, age, school career, a circuit speed, a period of using, joining frequency and a using place, past experience of winning a premium, purchasing information search, interesting connection on the internet, the risk about the negative evaluation of other persons, the economical values of premiums, winning possibility, and preferable premiums. (3) When looking at the influence of variables about the attitude of application about internet premium advertisement, the most influence variables was the past experience of winning a premium, and next was winning possibility, sex, the interest about the premiums which made the consumer want to apply, the economical values of premiums, the purpose of purchase information search and the using time. The explanation of those variables were 22.6%. As the result of the Logistic analysis, it was found that the frequency of the internet connection, the past experience of winning premiums, the risk about the outflow of credit information, interesting premiums, and premium advertisement were the most important variables to affect the possibility of the behavior of application about internet premium advertisement critically.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.12 no.2
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• pp.99-107
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• 1998

This dissertationhas confirmed the non-flam mability of cast mold transformer that is increasingly used lately. As a research progress, the investigation has been performed on the installation status and each line of the subway system which have the most mold transformer accidents, and the impediment status of the transformer for rectifier and the high-voltage distribution transformer per each manufacturer. Then, a high voltage mold of the actual mold transformer has been installed in the horiwntal heating furnace and the heat has been applied by the standard heating temperature curve of KSF 2257(Fireproof testing meth od of the construction structures: 1993). Accordingly, the combustibility of the mold transformer based on the test results has been found that 78 minutes has been required for the complete burning per the KSF 2257 combustion test curve and that, after stopping the heat application of the horizontal furnace after ignition, the flame progress has not been made but shown as the self-extinguishing characteristics when the flame progress has been checked. Thus, the non-flammability and self-extinguishability of the mold transformer have been confirmed. The result of this dissertation has indicated that the accident involving mold transformer has been progressed and expanded by the dielectric breakdown or void due to the crack in the mold rather than a fire accident caused by a short-circuit or an overload.r an overload.