• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.7
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• pp.1393-1397
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• 2009

A high-speed wavelength swept laser, which is based on oscillation characteristics of a fiber Fabry-Perot tunable filter, is described. The laser is constructed by using a semiconductor optical amplifier, a fiber Fabry-Perot tunable filter, and 3.348 km fiber ring cavity. The wavelength sweeps are repeatatively generated with the repetition period of 61 kHz which is the first parallel oscillation frequency of the Fabry-Perot tunable filter for the low power consumption. Mode-locking is implemented by 3.348 km fiber ring cavity for matching the fundamental of cavity roundtrip time to the sweep period. The wavelength tuning range of the laser is 87 nm(FWHM) and the average output power is 1.284 mW.

• Journal of Biosystems Engineering
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• v.11 no.1
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• pp.24-30
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• 1986

In order to collect the engine performance data accurately, rapidly and reliabily, the microcomputer-based engine performance test system was developed and tested. The system measures engine shaft torque and speed, fuel consumption, exhaust gas temperature, engine shaft power and fuel consumption ratio. The system consisted of 32 channels 8 bit A/D converter, time clock, dynamic strain amplifier and signal conditioning circuits to amplify and filter the electrical signal from transducers. Most of transducers were devised for low cost, easy setting and self-manufacturing. The system has been installed on a small kerosene engine (DAEDONG NA50B).

• Journal of information and communication convergence engineering
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• v.6 no.3
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• pp.275-278
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• 2008

In this paper, I propose the full CMOS FLL(frequency locked loop) circuit. The proposed FLL circuit has a simple structure which contains a FVC(frequency-to-voltage converter), an operational amplifier and a VCO(voltage controlled oscillator). The operation of FLL circuit is based on frequency comparison by the two FVC circuit blocks. The locking time of FLL is short compared to PLL(phase locked loop) circuit because the output signal of FLL is synchronized only in frequency. The circuit is designed by 0.35${\mu}m$ process and simulation carried out with HSPICE. Simulation results are shown to illustrate the performance of the proposed FLL circuit.

• Journal of IKEEE
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• v.18 no.1
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• pp.19-24
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• 2014

We report stable, wideband, flat-topped, 10 GHz optical frequency comb generation from a semiconductor-based mode-locked ring laser with an intra-cavity high finesse Fabry-Perot etalon. We demonstrate a stable 10 GHz comb with greater than 200 lines within a spectral power variation below 1 dB, which is the largest value obtained from a similar mode-locked laser in our knowledge. Greater than 20 dB of the spectral peak to deep ratio at 0.02 nm resolution, ~92 femtosecond timing jitter over 1 kHz to 1 MHz range, and non-averaged time traces of pulses confirm very stable optical frequency comb lines.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.55 no.4
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• pp.224-230
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• 2006

The conventional way to implement a bidirectional converter with boost/buck has been to use two general purpose PWM ICs with a single supply voltage. In this case, when one direction mode is in operation, the other is disabled and the output of the error amplifier of the disabled IC may be saturated to a maximum value or zero. Therefore, during mode transition, a circuit which can disable the switching operation for a certain time interval is required making it impossible to get a seamless transition. In this paper, the limitations of the conventional 42V/14V bi-directional DC/DC converter implemented with general current mode PWM ICs with a single supply voltage are reviewed and a new current mode PWM controller circuit with a dual voltage system is proposed. The validity of the proposed circuit is investigated through simulation. and experiments.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.25 no.9
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• pp.686-691
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• 2012

In this paper, we designed a Chua's chaotic circuit using transcondcutor based nonlinear resistor. Proposed chaotic circuit consist of L, C, R and transcondcutor based Chua's diode. We performed SPICE simulation for chaotic dynamics such as time seriesform, frequency analysis and phase plane of the circuit. Chaotic dynamics of the circuit was analysed according to MOS size variation of the operational transconductance amplifier. Also, we performed SPICE circuit analysis for temperature dependance of the circuit. SPICE results showed that chaotic dynamics of the circuit varied according to the temperature variation and chaotic signals were generated in specific temperature conditions.

• 제어로봇시스템학회:학술대회논문집
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• 1989.10a
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• pp.541-546
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• 1989

In case there are many points to be measured in the field, conventional measuring system requires a lot of manpower and is liable to miss applying the timely countermeasure because processing and analyzing the data obtained also takes much time. Therefore the purpose of this paper is focused on removing the above defects by introducing automatic multi-point measuring system by use of IBM-PC or the compatibles easily at hand nowadays. Principal components of the system is composed of control box, A/D converter. 32 channel 4 wire switch boxes and strain amplifier. An application software was developed for multi point measurement system in order to efficiently evaluate the stability of the structures such as retaining walls.

• Proceedings of the IEEK Conference
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• 2002.07b
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• pp.747-750
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• 2002

A circuit building block for realizing a continuous-time active-only current-mode integrator is presented. The proposed integrator is composed only of internally compensated type operational amplifier (OA) and operational transconductance amplifiers (OTAs). The integrator is suitable for integrated circuit implementation in either bipolar or CMOS technologies, since it does not require any external passive elements. Moreover, the integrator gain can be tuned through the transconductance gains of the OTAs. Some application examples in the realization of current-mode network functions using the proposed current-mode integrator as an active element are also given.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.32A no.1
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• pp.166-178
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• 1995

An accurate threshold voltage extraction scheme for MOS transistors is presented. In contrast to alternative methods recently reported in the literature, this scheme does not need matched replica of the transistor under test, and thus can be applied more effectively and accurately to raal-time on-chip applications where threshold voltage measurements are required for many transistors with various geometries and bias conditions. The proposed scheme is accurately implemented in a matching-free way using a ratio-indepentent switched-capacitor subtracting amplifier and a dynamic current mirror. Nonideal effects associated with these circuits have been investiggated and compensated.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.494-497
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• 2003

A rotating device driven by an Inchworm motor was designed and fabricated to be used as an angie standard system. 1. PZT was adopted as a driving source, while the movement of PZT was guided by the leaf spring employing the elastic transformation of metals. 2. The device could rotate in a 360-degree arc. continuously Performance test of the device showed about 0.02 sec. of the minimum revolution angle and 1/15 rpm of the maimum revolution speed. 3. To improve its performance requires further studies on realizing a shifting device with faster response time, on increasing the output current (capacity) of the power amplifier used to drive PZT, on the dynamic motion of clamping. and on determining the optimum clamping condition