• Journal of Advanced Marine Engineering and Technology
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• v.32 no.8
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• pp.1257-1262
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• 2008

A long-distance remote sensing of temperature and current based on a fiber Bragg grating (FBG) is proposed and demonstrated. The thermal expanding effect of the epoxy and the Er-doped fiber ring laser (EFRL) are applied to the sensor system to enhance the temperature and current sensitivity. An EFRL with a 5 km-single-mode fiber and a FBG shows a high extinction ratio of more than 60 dB and a low power fluctuation of less than 1 dB. The metal wires are used to supply the current to the sensors. When the NOA65 puts on the FBG as a thermal expanding material, the temperature and current sensitivity of the lasing wavelength shift are about $30\;pm/^{\circ}C$ and 3pm/mA, respectively. The proposed sensing scheme is useful for measurement of current or temperature at a distant object of more than several km.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.38 no.5
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• pp.367-373
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• 2001

A programmable A/D converter is designed with 8 N and P channel MOSFETs, respectively. In order to observe linear programmability of the EEPROM device during programming mode, a cell is developed with a 1.2 ${\mu}{\textrm}{m}$ double poly CMOS fabrication process in MOSIS. It is observed that the high resolution, of say 10m Volt, is valid in the range 1.25volts to 2volts. The experimental result is used for simulating the programmable 8 bit A/D converter with Hspice. The A/D converter is demonstrated to consume low power, 37㎽ by utilizing a programming operation. In addition, the converter is attained at the conversion frequency of 333 MHz.

• Proceedings of the KIPE Conference
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• 2001.10a
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• pp.457-461
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• 2001

Advantages of switched reluctance motor(SRM) drives make it an attractive candidate for replacing adjustable speed ac and dc drives in both industrial and consumer applications. Furthermore, a simple, low cost and robust SRM drive can be efficiently operated in the hostile environment of an automobile. Generally, the speed control of SRM has a large step change or large torque reference, the output of its PI controller is often saturated. When this happens, the integral state is not consistent with the SRM input, while may give rise to the windup phenomenon. This paper proposes anti-windup control method for SRM speed control system by hysteresis current controlled asymmetry bridge converter. The experimental results show that the speed response has much improved performance, such as a small overshoot and fast settling time at the acceleration and particulary deceleration period with braking mode.

• Proceedings of the KIPE Conference
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• 2001.10a
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• pp.761-767
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• 2001

In this paper, filtering techniques to reduce the adverse effects of motor leads on high-frequency PWM inverter fed AC motor drives will be examined. The filter was designed to keep the motor terminal from the cable surge impedance to reduce overvoltage reflections, ringing, and the dv/dt, di/dt. Therefore, filtering techniques are investigated to reduce the motor terminal overvoltage, ringing, and EMI noise in inverter fed ac motor drive systems. The output filter is used to limit the rate of the inverter output voltage and reduce EMI(common mode noise) to the motor. The performance of the output filter is evaluated through simulations (PSIM) and experiment on PWM inverter-fed ac motor drive(3phase, 3hp(2.2kw), input voltage 220/380V, induction motor). An experimental PWM drive system reduction of conducted EMI was implemented on an available TMS320C31 microprocessor control board. Finally, experimental results showed that the inverter output filter reduces more CM noise than the LPF(low pass filter) and reduce overvoltage and ringing at the motor terminal.

• Aerospace Engineering and Technology
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• v.7 no.2
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• pp.170-175
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• 2008

In this study, it was investigated that the characteristics of startup and compatibility using several type hot and cold gases. The characteristics of starting LRE by pyro starter was compared with that by a Helium spinner. The compatibility of pyro gas, a gaseous Helium, Hydrogen+Nitrogen mixture gas, and air was investigated by a simple 1D turbine analysis considered the properties of each gas and turbine efficiency. Most of them were compatible to start up the LRE however air was properly used only for low power mode of turbine.

• JSTS:Journal of Semiconductor Technology and Science
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• v.12 no.3
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• pp.278-285
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• 2012

A digital readout IC for capacitive sensors is presented. Digital capacitance readout circuits suffer from static capacitance of sensors, especially single-ended sensors, and require large passive elements to cancel such DC offset signal. For this reason, to maximize a dynamic range with a small die area, the proposed circuit features digital filters having a coarse and fine compensation steps. Moreover, by employing switched-capacitor circuit for the front-end, correlated double sampling (CDS) technique can be adopted to minimize low-frequency device noise. The proposed circuit targeted 8-kHz signal bandwidth and oversampling ratio (OSR) of 64, thus a $3^{rd}$-order ${\Delta}{\Sigma}$ modulator operating at 1 MH was used for pulse-density-modulated (PDM) output. The proposed IC was designed in a 0.18-${\mu}m$ CMOS mixed-mode process, and occupied $0.86{\times}1.33mm^2$. The measurement results shows suppressed DC power under about -30 dBFS with minimized device flicker noise.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.38 no.9
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• pp.869-874
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• 2010

Recently, a piezo actuator based linear motor has been actively studied because of its higher power density, compactness and quick response. However, the characteristic of small displacement makes the application of a piezo actuator limitative. In order to overcome this limitation, some actuation mechanisms using a piezo actuator are designed by bi-metal composite or more than two piezo actuators. Therefore, it enables to generate large displacement and have high resolution. In the proposed piezo motor, we have designed a bi-directional linear motor that can be operated by only one piezo actuator. In addition, it is activated with low frequency of the applied voltage, since, we utilize first mode shape of structure of motion generator to vibrate. Finally, moving direction can be simply controlled by changing the ratio of input frequency to natural frequency of structure of motion generator.

• Proceedings of the KIEE Conference
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• 2008.10b
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• pp.536-537
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• 2008

최근 홈 네트워킹 기술과 연동된 가전제어 및 서비스에 대한니즈가 증대�� 있어 다양한 디지털 가전기기가 개발되고 있다. 특히 국내외적으로 많은 홈 네트워크 관련 제품들이 생산되고 있으며 이는 궁극적으로 이기종 네트워크 환경에서 유무선 통신의 구된 없이 다양한 기기를 네트워크에 접속할 수 있는 서비스를 제공한다. 기존 중 저속 전력선 모뎀의 경우 홈 네트워크에서 전력선으로 들어오는 신호를 수신하기 위해 전력소모가 가장 많은 Main Processor에서는 항상 Wake-On 상태를 유지하고 있다. 하지만 중 저속 전력선 모뎀의 송수신을 관장하는 Main Processor를 보게 되면 크게 통신 프로토콜을 관장하는 Main CPU와 실제 전력선 신호 송수신을 관장하는 PLC Core로 나뉠 수 있다. 홈네트워크상에 전력선으로 들어오는 신호를 수신하기 위해서는 PLC Core는 항상 Wake-On 상태를 유지해야 하지만 Main CPU의 경우는 전력소모를 최소화하기 위해 Idle 상태를 유지하더라도 Host Controller와의 Stand-by & Wake On 신호와 인터럽트 발생기능을 이용하게 되면 전력선 통신에 문제가 없이 대기모드를 지원하는 저전력 전력선 통신 모뎀 개발이 가능하다. 이에 본 연구에서는 저전력 대기모드를 지원하는 전력선 통신 모뎀 개발에 관한 연구를 하고자 한다.

• Journal of Advanced Navigation Technology
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• v.20 no.4
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• pp.361-366
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• 2016

This paper presents an arbitrary impedance transformer with unequal split, based on S- to admittance parameter conversion. When compared even/ odd- mode analysis, the parameter conversion design method constitutes a simple design method to include phase delay information and arbitrary port impedances and asymmetrical configurations. To validate this design method, we designed a 50 to $12.5{\Omega}$ impedance transformer with a 3:1 unequal power split, at an operating frequency of 1 GHz. To implement the proposed impedance transformer, the low impedance transmission lines of calculated result are fabricated by the transmission line connected shunt open stub. Good experimental performances were obtained, in full agreement with simulated results.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.13 no.1
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• pp.17-22
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• 2009

A switch or circulator is used for distinguishing between the paths of transmitter and receiver in TDD systems. If the isolation between Tx and Rx paths is low in TDD systems, the output signal of the ransmitter acts as an interferer to the receiver even if the transceiver operates on the receiver mode. In this paper we propose a method to get high isolation characteristics between transmitting and receiving paths in TDD systems. We implement the module with a proposed improving method to verify the effect of the isolation improvement and the experimental results are presented. The isolation improvement of above 44.8 dB over the frequency bandwidth of 30 MHz is obtained from the implemented isolation improvement module.