• Journal of the Institute of Electronics and Information Engineers
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• v.49 no.12
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• pp.219-225
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• 2012

A low-power, low-noise pre-amplifier for digital hearing-aid application is designed. This pre-amplifier amplifies single-ended signal from an electret microphone, and produces differential output to be delivered to an ADC. It has a variable gain of 3.6, 7.2, 14.4 and 28.8 with a bandwidth between 100Hz~10kHzon. The measurement results show 85 dB of SNR, 0.05 % of harmonic distortion and $200{\mu}W$ of power consumption with 1.2V supply.

• Journal of Institute of Control, Robotics and Systems
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• v.18 no.6
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• pp.532-539
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• 2012

This paper proposes a balancing and driving control system for a bicycle robot. A reaction wheel pendulum control method is adopted to maintain the balance while the bicycle robot is driving. For the driving control, PID control algorithm with a variable gain adjustment has been developed in this paper, where the gains are heuristically adjusted during the experiments. To measure the angles of the wheels the encoders are used. For the balancing control, a roll controller is designed with a non-model based algorithm to make the shortest cycle. The tilt angle is measured by the fusion of the acceleration and gyroscope sensors, which is used to generate the control input of the roll controller to make the tilt angle zero. The performance of the designed control system has been verified through the real experiments with the developed bicycle robot.

• Journal of Institute of Control, Robotics and Systems
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• v.18 no.6
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• pp.526-531
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• 2012

This paper, we describe the vector control of surface mounted PMSM (Permanent Magnet Synchronous Motor) using the fuzzy controller which is suggested algorithm. In these days, when vehicle is operated or not, whether the road is covered or not, the sensitivity of the steering column is not stable. To make up for it, the PI gain of a steering column controller is adjusted by experience. It becomes the price because it need a lot of sensor. Also it is difficult to implement robust control because we need a lot of parameters for variable road conditions which are the off road, the on road, a low battery voltage, a high battery voltage, a vehicle speed. In this paper, we propose fuzzy controller using the suggested algorithm which suitable for steering system. We test the fuzzy controller with the various condition. We get the good performance of fuzzy controller even if it is nonlinear system. We check a robust the fuzzy controller using the suggested algorithm.

• Journal of Advanced Marine Engineering and Technology
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• v.16 no.4
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• pp.102-112
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• 1992

The three-phase full(6-pulse) bridge controlled rectifier is one of the most widely used types of solid-state converters in DC drive applications for higher performance. In most of the previous designs, the gate control circuits of the converter have been designed with analog method which can be easily affected by noise. Nowdays with advances of microelectronics and power electronics, microprocessor and pheripal LSIs are increasingly used for eliminating this problems. In this paper, a novel general-purpose microprocessor -based firing system and control scheme for a three-phase controlled rectifier bridge has been developed and tested. Using the phase relations between ${\Delta}$-Y transformer in power operation part, gate pulse of the converter is generated with real time process so that microprocessor may share its time to control algorithms efficiently. The firing angle of the converter is smoothly controlled in the range of 0 $^{\dirc}$ to 180$^{\dirc}$ with a fast respone and a constant open loop gain, even for the case where the converter is fed by a weak AC system of unregulated frequency. The hardware and software control circuit implementation built around a 80286 microprocessor is discussed, and the experimental results are given. This scheme uses less hardware components and has higher dynamic performance in variable speed DC drive applications.

• Journal of international Conference on Electrical Machines and Systems
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• v.2 no.1
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• pp.97-103
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• 2013

This paper describes the characteristics of Electronic Throttle Controller (ETC) module in BLDC motor without the hall sensor for detecting a rotor position. The proposed ETC control system, which is mainly consisted of a BLDC motor, a throttle plate, a return spring and reduction gear, has a position sensor with an analogue voltage output on the throttle valve instead of BLDC motor for detecting the rotor position. So the additional commutation information is necessarily needed to control the ETC module. For this, the estimation method is applied. In order to improve and obtain the high resolution for the position control, it is generally needed to change the gear ratio of the module or the electrical switching method etc. In this paper, the 3-phase switching between successive commutations is adapted instead of the 2-phase switching that is conventionally used. In addition, the position control with a variable PI gain is applied to improve a dynamic response during a transient period and reduce vibration at a stop in case of matching position reference. The mentioned method can be used to estimate the commutation state and operate the high-precision position control for the ETC module and the high response characteristics. The validity of the proposed method is examined through the experimental results.

• Journal of Institute of Control, Robotics and Systems
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• v.16 no.11
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• pp.1029-1037
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• 2010

If an internal combustion engine is operated by consolidated control, the minimum fuel consumption is achieved and the demanded objectives are satisfied. For this, it is necessary that the engine is operated on the ideal operating line which satisfies minimum fuel consumption. In this context of view, there are many tries to achieve given object. However, the parameters in the internal combustion engines are variable and depend on the operating points. Therefore, it is necessary to cope with the uncertainties such that the optimal operating may be possible. From this point of view, this paper gives a controller design method and a robust stability condition for engine torque control which satisfies the given control performance and robust stability in the presence of physical parameter perturbation. Exactly, in this paper, we consider the robust stability problem of this 2DOF servosystem with nonlinear type uncertainty in the engine system, and a robust stability condition for the servosystem is shown. This result guarantees that if the plant uncertainty is in the permissible set defined by the given condition, then a gain tuning can be carried out to suppress the influence of the plant uncertainties.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.36S no.8
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• pp.113-122
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• 1999

A new resonant switching Watkins-Johnson converter was proposed, which minimizes the switching loss and is well suited for high-frequency operation. The steady-state analyses revealed that the voltage gain of the proposed converter is solely determined by the switching frequency. Consequently, to regulate the output voltage of the converter for variable load current the switching frequency should be varied accordingly. Based on the results of analyses, an optimum design procedure for the resonant component values is proposed, which minimized the voltage stress of power switch while maintaining the desired property of zero-voltage switching. Finally, accuracy of analyses and validity of an optimum design procedure are verified on an experimental resonant switching Watkins-Johnson converter prototype.

• Publications of The Korean Astronomical Society
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• v.21 no.1
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• pp.11-20
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• 2006

We carried out a follow-up study on the students who participated in International Astronomy Olympiad(IAO). We surveyed home and school environment, personal characteristics with regard to four high school student and five college students who participated in IAO from 2002 to 2005. In the home environment variable of science elite students who took part in the IAO, we found out significant corelation between science elites and their parent's educational career. In their personal characteristics, we found out considerably their motivation capacity, intelligent curiosity, flexible and creative thinking ability. This study illuminated that the experience of IAO participation offered the opportunity for the students to gain mare self-esteem and positive confidence on scientific study. The IAO experience is construed to effect greatly the students' future. Through the IAO experience, the participating students are expected to major in astronomy and become excellent astronomers in the future. We expect that the interest of student will increase greatly in the area of astronomy and it will contribute to the substantial development of Korean astronomy. In this respect, with the constant support to the IAO participants, the effort to cultivate outstanding astronomers and follow-up study on those participants of the IAO should be continued.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.28A no.1
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• pp.40-45
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• 1991

It is well known that the conventional differential source-coupled pair uses gates as its input terminals. This input pair provids a high open-loop gain, a large CMRR, and a good PSRR. For these reasons, the input pair has been used widely as an input stages of the differential amplifiers, but a narrow linear input range of this structurelimits its application in the area of some analog circuit design. A novel CMOS source-coupled backgate pair is proposed in this paper. The bulk of MOSFET is exploited and input devices are biased to operate in ohmic region. With this topology, the backgate pair of the wide linear input range and variable transconductance can be obtained. This backgate input differential stage is realized with the size of W/L=50/25 MOSFETs. The results show the nonlinear error is less than $\gamma$1% over 10V full-scale range for the bias current of 200$\mu$A with 10V single power-supply.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.12
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• pp.1410-1415
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• 2008

This paper proposes an small electronically steerable parasitic array radiator composed of a uniplanar dipole as a feeding element and two dipoles as parasitic elements. The fabricated antenna shows by measurement the $3.3{\sim}4.3\;dB$ gain between $-100{\sim}1000$ azimuth range in the dipole vertical plane and -10 dB return loss within $5.4{\sim}5.9\;GHz$, which includes $5.725{\sim}5.825\;GHz$ UNII band.