• Journal of Sensor Science and Technology
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• v.29 no.4
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• pp.270-274
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• 2020

In this study, a read-out integrated circuit (ROIC) that can be applied to a colorimetry-based optical sensor for analyzing total phosphorus and total nitrogen was developed and characterized. The proposed ROIC minimizes the effect on temperature fluctuation, improves sensitivity, and extends the dynamic range by utilizing a dual optical path and feedback control circuit. Using a dual optical path makes it possible to calibrate the output signal of the optical sensor automatically, along with the temperature fluctuation. The calibrated voltage is fed back into the measurement stage; thus, the output current of the measurement is adaptively controlled. As a result, the sensitivity and dynamic range of the proposed ROIC are improved. Finally, a total-phosphorus analysis was conducted by utilizing the ROIC. The ROIC was found to operate stably over a wide temperature range.

• Journal of the Korean Society of Hazard Mitigation
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• v.10 no.2
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• pp.77-81
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• 2010

D&B(Drill & Blast) method in tunnel construction requires accurate and rapid measurement of the ground movement, which is essential for feedback analysis. Case study and adaptability of IT technique for tunnel survey are discussed in this paper. The application of laserscannig and existing light wave instrument method in the field of tunnel construction were reported in several advanced country including Austria and Japan. Survey for the shoulder movements by IT survey method was conducted at a subway construction site and the results were compared to the conventional method. Also, the economic aspects of laserscannig method were analyzed using measured data which were categorized by expenses, frequency, interval and period in the field of construction. Therefore IT survey solution may contribute to execute more economic and safe construction

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.1
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• pp.720-725
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• 2015

This paper describes the design of a wideband cascode amplifier using a feedback network and microwave small-signal transistors. The adopted cascode structure enables the miller effect to be lessened, cutoff frequency to increase, and reduction of gain in the mid-band to be mitigated. In addition, a feedback network is added to the cascode structure to improve the input matching and ripple performances over the wide operating band. The designed cascode amplifier contains a feedback network for small size and broadband amplification, whereas balanced amplifiers and distributed amplifiers have been used widely. The measurement shows $8.5dB{\pm}1.5dB$ of gain over 1000-2000MHz. The fabricated cascode amplifier has more than 8dB of gain over a 1000MHz bandwidth with a good flatness. The measured performances agree with the predicted ones even a minor shift in operating frequency is observed.

• Journal of Sensor Science and Technology
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• v.24 no.2
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• pp.131-136
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• 2015

This paper presents a wide dynamic range complementary metal oxide semiconductor (CMOS) image sensor with column capacitor and feedback structure. The designed circuit has been fabricated by using $0.18{\mu}m$ 1-poly 6-metal standard CMOS technology. This sensor has dual mode operation using combination of active pixel sensor (APS) and passive pixel sensor (PPS) structure. The proposed pixel operates in the APS mode for high-sensitivity in normal light intensity, while it operates in the PPS mode for low-sensitivity in high light intensity. The proposed PPS structure is consisted of a conventional PPS with column capacitor and feedback structure. The capacitance of column capacitor is changed by controlling the reference voltage using feedback structure. By using the proposed structure, it is possible to store more electric charge, which results in a wider dynamic range. The simulation and measurement results demonstrate wide dynamic range feature of the proposed PPS.

• 제어로봇시스템학회:학술대회논문집
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• 1997.10a
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• pp.321-324
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• 1997

In this paper, Active Noise Control(ANC) algorithm is proposed based on the estimated frequency estimator of the reference signal. The conventional feedforward ANC algorithms should measure the reference and use it to calculate the gradient of the squared error and filter coefficients. For ANC systems applied to aircrafts and passenger ships, engines from which reference signal is usually measured is so far from seats where main part of controller is placed that the scheme might be difficult to implement or very costly. Feedback ANC algorithm which doesn't need to measure the reference uses the error signal to update the filter and is sensitive to unexpected transient noise like a sneeze, clapping of hands and so on The proposed algorithm estimates frequencies of the desired signal in real time using adaptive notch filter. New frequency estimation algorithm is proposed with the improved convergence rate, threshold SNR and computational simplicity. Reference is not measured but created with the estimated frequencies. It has strong similarity to the conventional feedback control because reference is made from error signal. Enhanced error signal is used to update the controller for better performance under the measurement noise and impact noise. The proposed ANC algorithm is compared with the conventional feedback control.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.37 no.1
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• pp.1-9
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• 2000

In this paper, we design a robust output feedback controller for robot manipulators with bounded parametric uncertainties using high-gain observer. The proposed control scheme with integral action improves tracking error due to limit of the robust feedback gains. High-gain observer is used to solve the noise problem with the joint velocity measurement. This controller avoids the limitation on the variation of unknown parameters and guarantees the uniformly ultimate boundedness of the closed-loop system. The performance of the proposed method is demonstrated by simulation on a 2-link manipulator.

• 제어로봇시스템학회:학술대회논문집
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• 1993.10a
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• pp.1199-1205
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• 1993

It has been well known that the assumption of full state availability is one of the most important restrictions to the practical realization of VSCS. And several attempts to alleviate the assumption had been made. However, it is not easy to find a positive scheme among them. Recently, an output feedback variable structure control system(OFVSCS) was proposed and the effectiveness of the scheme was validated for the disturbance free systems. The purpose of this study is to propose a robust OFVSCS that have the robust properties against process parameter variations and external distrubances by extending the basic OFVSCS and to evaluate its control performances through power system stabilizer design example. The ROFVSCS is composed of dynamic switching function and output feedback switching control inputs that are constructed by the use of the unknown vector modeling technique. With the proposed scheme, existence of sliding mode is guaranteed and any nonzero bias can be suppressed in the face of disturbances and process parameter variations as far as well-known matching condition is satisfied. Due to the fact that the ROFVSCS is driven by small number of measured informations, the practical application of VSCS for the systems with unmeasurable states and for high order systems that conventional schemes cannot be applied, is possible with the proposed scheme. It is noticeable that the implementation cost of VSCS can be considerably reduced without sacrifice of control performances by adopting ROFVSCS since there is no need measure the states with high measurement cost.

• 제어로봇시스템학회:학술대회논문집
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• 1996.10b
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• pp.1352-1355
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• 1996

The control of diamond turning is usually achieved through a laser-interferometer feedback of slide position. If the tool post is rigid and the material removal process is relatively static, then such a non-collocated position feedback control scheme may surface. However, as the accuracy requirement gets tighter and desired surface contours become more complex, the need for a direct tool-tip sensing becomes inevitable. The physical constraints of the machining process prohibit any reasonable implementation of a tool-tip motion measurement. It is proposed that the measured force normal to the face of the workpiece can be filtered through an appropriate admittance transfer function to result in the estimated depth of cut. This can be compared to the desired depth of cut to generate the adjustment control action in addition to position feedback control. In this work, the design methodology on the admittance model-based control with a conventional controller is presented. The recursive least-squares algorithm with forgetting factor is proposed to identify the parameters and update the cutting process in real time. The normal cutting forces are measured to identify the cutting dynamics in the real diamond turning process using the precision dynamometer. Based on the parameter estimation of cutting dynamics and the admittance model-based nanodynamic control scheme, simulation results are shown.

• Korean Journal of Optics and Photonics
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• v.9 no.2
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• pp.96-99
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• 1998

In this study, a novel long term stabilization method of optical feedback for the resonant cavity coupled semiconductor lasers is proposed, and its utility was shown experimentally. The proposed method is realized by using the pahse discriminator of optical feedback with high gain. The phase discriminating signal was obtained by the polarization spectroscopic technique using reflection light from the external reflector, which is a confocal Fabry-Perot cavity. Experimental result shows that stable control state can be maintained up to 20 hours. The period can be increased by reducing size of the system and/or fixing position stably of optical parts used, which were arranged on an optical table by using magnetic bases in this experiment. The proposed long-term stabilization method of optical feedack of a resonant external cavity coupled semiconductor laser is very useful for the field of high sensitivity measurement, and for the use in the laboratory level in particular.

• The Journal of Korean Physical Therapy
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• v.24 no.1
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• pp.1-6
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• 2012

Purpose: The grip strength is influenced by various factors, such as position of the upper extremity, characteristics of the hand, and general physical condition. In this study, we investigated whether abdominal muscle activity in combination with the abdominal drawing-in maneuver has any effect on the grip strength in healthy young adults. Methods: This study included 31 healthy subjects (16 males, 15 females). We used surface electromyography and pressure bio-feedback unit for this experiment. All Subjects were placed in a cock-lying position with comfort and the grip strength was measured. On the following day, the pressure bio-feedback unit was placed beneath their fifth lumbar vertebra, and the, grip strength was measured again. This time, the measurement was taken while drawing-in their abdomen below the navel gently and gradually, while maintaining a neutral pelvic position. Results: The grip strength was significantly increased when subjects performed the drawing-in maneuver than when they were comfortable (p<0.05). In addition, activations of the rectus abdominal muscles significantly increased (p<0.05). Conclusion: In the current study, we found that abdominal muscle activity, in combination with the abdominal drawing-in maneuver, affected the grip strength, positively. Therefore, we suggest that this result should be considered when evaluating the grip strength.