• Proceedings of the IEEK Conference
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• 1999.11a
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• pp.963-966
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• 1999

This Paper describes the design of high speed and low power comparator based on the feed forward bias control. Major building blocks of this comparator are composed of input offset canceling circuit and feed forward bias control circuit. The usual offset canceling circuit cancels the offset voltages by storing them in capacitors using MOS switches, The comparator of this paper employs the bias control circuit which generates bias signal from the input signal. The bias signal is applied to the capacitors and keeps the transfer of chares in the capacitors in the minimal amount, therefore making the comparator operate in stable condition and reduce decision time. The comparator in this form has very samll area and power dissipation. Maximum sampling rate is 200 Ms/sec. The comparator is designed in 0.65${\mu}{\textrm}{m}$ technology and the offset is less than 0.5㎷.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.05a
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• pp.991-995
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• 2002

The engine booming noise heard inside a vehicle's cabin is due to the engine vibration that's transferred to the chassis in the form of structural vibration and it often causes discomfort to the passenger. In an effort to seek out the possible relation between the engine booming noise and the engine vibration of a vehicle, a position on the engine mount was selected and the vibration transmission through the position was attenuated to observe the corresponding change in the noise level inside the cabin. A system consisting of an actuator and a hybrid controller that has both the feed-forward and feed-back capabilities was developed in order to carry out the experiment.

• Journal of the Institute of Convergence Signal Processing
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• v.1 no.2
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• pp.153-159
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• 2000

The cable installed will have catenary's type that is nonlinear and variable time system. Because it has a close relation to the catenary's type to determine command value of tension for the tension control of this cable, we need to study it. The purpose of this study is automated the installation equipment (or a catenary's cable. This study shows control system that the tension of a catenary's cable is keep constant. 'rho control method is adopted the fuzzy control that is robust because the model of a control object is nonlinear and variable time system and feed-forward control to suppress overshoot as a shift begins to move. On the basis of the dynamic modeling of a catenary's cable we compose the control system with adopting fuzzy and feed-forward control has recognized the effectiveness in simulation results.

• JSTS:Journal of Semiconductor Technology and Science
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• v.15 no.3
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• pp.319-325
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• 2015

This paper presents an efficient vibration energy harvester with a piezoelectric (PE) cantilever. The proposed PE energy harvester increases the efficiency through minimization of hardware complexity and hence reduction of power dissipation of the circuit. Two key features of the proposed energy harvester are (i) incorporation synchronized switches with a simple control circuit, and (ii) a feed-forward buck converter with a simple control circuit. The chip was fabricated in $0.18{\mu}m$ CMOS processing technology, and the measured results indicate that the proposed rectifier achieves the efficiency of 77%. The core area of the chip is 0.2 mm2.

• Journal of Power Electronics
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• v.18 no.6
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• pp.1780-1790
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• 2018

Voltage feed-forward control (VFFC) is widely used in LCL-type grid-tied inverters due to its advantages in terms of disturbance rejection performance and fast dynamic response. However, VFFC may worsen the stability of inverters under weak grid conditions. It is revealed in this paper that a large phase-lag in the low-frequency range is introduced by VFFC, which reduces the phase margin significantly and leads to instability. To address this problem, a novel virtual-impedance-based control, where a phase-lead is introduced into the low-frequency area to compensate for the phase lag caused by VFFC, is proposed to improve system stability. The proposed control is realized with a high-pass filter, without high-order-derivative components. It features easy implementation and good noise immunity. A detailed design procedure for the virtual impedance control is presented. Both theoretical analysis and experimental results verify the effectiveness of the control proposed.

• Journal of Biosystems Engineering
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• v.16 no.2
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• pp.124-132
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• 1991

This study was carried out to obtain the information needed in the development of forward speed control system and the improvement of combine performance. The effects of variety, grain moisture content and forward speed on the combine load characteristics were investigated through experiments. The results of this study are summarized as follows. 1. A data acquisition system was developed to measure the engine speed and the torques and speeds of the threshing cylinder, dean-grain auger and tailings-return auger. The system consisted of transducers, signal conditioner, interface board and microcomputer. The system accuracy is better than ${\pm}2.3%$ full scale. 2. Linear regression equations were obtained for the torque, speed and power requirement of threshing cylinder for different paddy varieties, grain moisture contents and feed rates. 3. The maximum value of relative frequency for threshing cylinder torque decreased as the increase in feed rate and moisture content. The range of torque fluctuation was 1.2~3.7 and 1.2~1.9 times the average and maximum torque, respectively. The maximum value of power spectrum density (PSD) appeared to be about 11 Hz regardless of paddy variety, grain moisture content and feed rate. 4. The speed of tailings return thrower decreased rapidly at below 900rpm, and it fell to near zero about 3 seconds after that time. When the travelling of combine harvester was stopped immediately after sensing the overload, it took about 7 seconds for a full recovery of the no-load speed of tailings return thrower.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.44 no.5
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• pp.50-57
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• 2007

A 5Gbps CMOS　adaptive feed-forward equalizer designed for backplane applications is described. The equalizer has adaptive feedback circuits to control the compensating gain of the equalizing filter, which uses a phase detector in clock recovery circuit to detect ISI (Inter-Symbol Interference) level. This makes the equalizer operate adaptively for a various channel length of backplane environments.

• The Journal of Korean Physical Therapy
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• v.18 no.4
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• pp.51-60
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• 2006

Purpose: This study was to compare the effect of center of pressure(COP) displacement and muscle activation onset during expected and unexpected sudden limb loading in subjects with low back pain and healthy control subjects. Most studies of COP displacement and muscle activation onset on postural task focused on sudden trunk loading or gross limb movements. Investigation of the COP displacement and muscle activation onset during expected and unexpected sudden upper limb loading deserves similar attention. Methods: For this study, 14 subjects with low back pain and 12 healthy control subjects are participated. Force plate and surface EMG measures were used to determine COP displacement and muscle activation onset under expected and unexpected sudden upper limb loading. Results: COP displacement and muscle activation onset under unexpected sudden upper limb loading were similar in subjects with low back pain and healthy control subjects. However, COP displacement and muscle activation onset under expected sudden upper limb loading were shortened in healthy control subject but not among the subjects with low back pain. Conclusion: The results provide evidence for impaired feed-forward control in subjects with low back pain.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.45 no.5
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• pp.401-408
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• 2017

This paper describes development and validation processes of a low-cost hardware based flight control computer designed for multi-rotor UAVs. The developed flight control computer controls multi-rotors stable and can handle complex flight missions using an integrated high-performance Linux computer. A complementary filter generates a navigation solution with 500 Hz, and a proposed observer significantly reduces measurement noise. A control algorithm utilizes a feed-forward term computed by a three-dimensional curve fitting method, and it increases tracking performance. The developed flight control system has been fully tested through several test flights, and it can apply to real flight environments.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.40 no.1
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• pp.24-36
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• 2003

The digital mobile communication will be developed till getting multimedia service in anyone, any where, any time. Theses requiring items are going to be come true via IMT-2000 system. Transmitting signal bandwidth of IMT-2000 system is 3 times as large as IS-95 system. That is mean peak to average of signal is higher than IS-95A system. So we have to design it carefully not to effect in adjacent channel. HPA(High Power Amplifier) located in the end point of system is operated in 1-㏈ compression point(Pl㏈), then it generates 3rd and 5th inter modulation signals. Theses signals affect at adjacent channel and RF signal is distorted by compressed signal which is operated near by Pl㏈ point. Then the most important design factor is how we make HPA having high linearity. Feedback, Pre-distorter and Feed-forward methods are presented to solve theses problems. Feed-forward of these methods is having excellent improving capacity, but composed with complex structure. Generally, Linearity and Efficiency in power amplifier operate in the contrary, then it is difficult for us to find optimal operating point. In this paper we applied algorithm which searches optimal point of linear characteristics, which is key in Power Amplifier, using minimum current point of error amplifier in 1st loop. And we made 2nd loop compose with new structure. We confirmed fabricated LPA is operated by having high linearity and minimum current condition with ACPR of -26 ㏈m max. @ 30㎑ BW in 3.515㎒ and ACLR of 48 ㏈c max@${\pm}$㎒ from 1W to 40W.