• 제어로봇시스템학회:학술대회논문집
• /
• 2001.10a
• /
• pp.94.4-94
• /
• 2001

An acoustic ranging system was applied for reckoning the location of an agricultural vehicle in the field. The system has a number of fixed stations and a mobile station such as an agricultural vehicle. The mobile station comprises a radio frequency modulator-demodulator (RF MODEM), a buzzer, and a personal computer. The fixed station comprises an (RF MODEM), a microphone, an amplifier for the microphone, and a personal computer with a soundboard. The mobile station transmits a 7-bit ASCII code and, activates the buzzer simultaneously. The propagation delay time at the fixed station is caused by the difference ...

• 제어로봇시스템학회:학술대회논문집
• /
• 2001.10a
• /
• pp.158.4-158
• /
• 2001

This paper presents a novel circuit configuration for realizing the continuous-time active-only voltage-mode integrator. The proposed integrator consists only of internally compensated type operational amplifier (OA) and operational transconductance amplifiers (OTAs). Since no external passive elements are required, the integrator is suitable for integrated circuit implementation in either bipolar or CMOS technologies. Moreover, the integrator gain can be electronically tuned by adjusting the bias currents of the OTAs. The characteristics of the proposed integrator and the effectiveness of the design procedure in realizing various analog transfer functions have been examined by PSPICE simulation.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
• /
• 2000.11a
• /
• pp.130-134
• /
• 2000

본 논문에서는 확장된 시간영역 유한차분법(Extended finite difference time domain method)을 이용하여 마이크로파 중폭기를 해석하였다. 회로에 포함되어 있는 능동 소자는 고주파 등가 회로를 이용하여 모델링 하였다. 고주파 등가 회로를 통하여 계산한 게어트와 드레인의 전류를 FDTD의 전계 계산식에 첨가향으로개 마이크로스트립 회로의 전자기파와 능동 소자와의 상호 작용을 특성 지었다. 해석 결과는 주파수 영역 회로 해석법(Frequency-domain circuit analysis)을 이용한 결과와의 비교를 통하여 정확성을 입증했다.

• Proceedings of the Korean Society for Emotion and Sensibility Conference
• /
• 1999.03a
• /
• pp.255-259
• /
• 1999

Easy check system for cardiac function was developed for computer user n this study. EKG amplifier was designed to remove a common noise and muscle noise. EKG pattern, and calculated real time heart rate and probability of arrhythmia were displayed in personal computer. This system would be an effective tool for checking cardiac function in everyone using computer.

• Bulletin of the Korean Chemical Society
• /
• v.17 no.1
• /
• pp.39-42
• /
• 1996

A new oscillator for electrochemical quartz crystal microbalance (EQCM) was developed by using an operational amplifier without any LC component. The home-made EQCM using this oscillator showed only 0.02 Hz frequency noise at 0.3 s gate time when a 6 MHz AT-cut crystal was used. Pb underpotential deposition on gold substrate in nitric acid media was examined to demonstrate the performance of this EQCM. The derivative of frequency change could be obtained without averaging multiple scans.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.16 no.6
• /
• pp.1250-1259
• /
• 2012

In this paper, a time-domain comparator is proposed for a successive approximation (SA) analog-to-digital converter (ADC) with a low power and high resolution. The proposed time-domain comparator consists of a voltage-controlled delay converter with a clock feed-through compensation circuit, a time amplifier, and binary phase detector. It has a small input capacitance and compensates the clock feed-through noise. To analyze the performance of the proposed time-domain comparator, two 1V 10-bit 200-kS/s SA ADCs with a different time-domain comparator are implemented by using 0.18-${\mu}m$ 1-poly 6-metal CMOS process. The measured SNDR of the implemented SA ADC is 56.27 dB for the analog input signal of 11.1 kHz, and the clock feed-through compensation circuit and time amplifier of the proposed time-domain comparator enhance the SNDR of about 6 dB. The power consumption and area of the implemented SA ADC are 10.39 ${\mu}W$ and 0.126 mm2, respectively.

• Journal of the Korean Institute of Telematics and Electronics B
• /
• v.32B no.12
• /
• pp.1572-1580
• /
• 1995

In this paper, a modified Chebyshev low-pass filter function is proposed. The modified Chebyshev filter function exhibits ripples diminishing toward .omega. = 0 in the passband. So, the modified filter function is realizable in the passive doubly-terminated ladder network for the order n even or odd, thus lending itself amenable to active RC or switched capacitor filters through the simulation techniques. Besides the passive doubly-terminated ladder realizability, lower pole-Q values of the modified function are accountable for improved phase and delay characteristics, as compared to classical function. We have designed the 6th order passive doubly-terminated network using the modified function. And then a continuous-time DDA(Differential Difference Amplifier) filter, which has no matching requirement, is realized by leap-frog simulation technique for fabrication. In the HSPICE simulation results, we confirmed that the designed continuous-time DDA filter characteristics are agreement with the passive filter.

• Journal of IKEEE
• /
• v.21 no.4
• /
• pp.375-380
• /
• 2017

A differential current-to-time interval converter is presented for current mode sensors. It consists of a ramp voltage generator, a current mode sensor, a reference current source, two current-tunable Schmitt triggers, a one-shot multivibrator, and two logic gates. The design principle is to apply a ramp voltage to each input of the two current-tunable Schmitt triggers whose threshold voltages are proportional to the drain current values of the current mode sensors. A proposed circuit converts a current change in the ISFET biosensor into its equivalent pulse width change. A prototype circuit built using TSMC 0.18 nm CMOS process exhibit a conversion sensitivity amounting to $726.9{\mu}s/pH$ over pH variation range of 2-12 and a linearity error less than ${\pm}0.05%$.

• Proceedings of the Optical Society of Korea Conference
• /
• 1989.02a
• /
• pp.20-25
• /
• 1989

The nonlinear, time dependent photon transport equations of Frantz and Nodvik, which describe the amplification of an optical pulse in an active medium, are modified to a simpler equation which describes only the amplification of energy. with this equation, the output energy of the high power YLF(Nd3+)-Phosphate Glass(Nd3+) Laser System is calculated. When the stored energy density Est is 0.10J/㎤, 0.16J/㎤, 0.228J/㎤, and 0.50J/㎤, and with the assumption of uniform population inversion density, the final output energy of this laser system is 5.38J, 176J, 317J, and 283J, respectively. The gain saturation causes distortion of the output beam. This phenomenon is described in detail at the first three rod amplifier systems in the case of E=0.228J/㎤. The peak current and decay time constant of the flashlamps, which are used to obtain population inversion in the active medium, are investigated. The flashlamp driving circuit which has optimum operational performance should have {{{{ SQRT { LC} }} time about 100$\mu$sec.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.24 no.9
• /
• pp.883-891
• /
• 2013

In wireless smart phone charging scenario, the transmitter pad is larger than the size of the receiver pad. Thus, it is important to supply a constant power to the receiver regardless of its location. In this paper, we propose a new method to regulate the receiver's power by adjusting a drain bias of class E power amplifier. The proposed LF-band wireless power transfer system is as follows: a buck converter power supply which is controlled by a pulse width modulation(PWM) IC TL494, a class E amplifier using a low cost IRF510 power MOSFET, a transmitter coil whose dimension is $16cm{\times}18cm$, a receiver coil whose dimension is $6cm{\times}8cm$, and a full bridge rectifier using Schottky diodes. A measured performance show a maximum output power of 4 W and system efficiency of 67 % if we fix the bias voltage. If we adjust the bias voltage, the received power can be maintained at a constant power of 2 W regardless of receiver pad location.