• Journal of Power Electronics
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• v.16 no.1
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• pp.18-26
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• 2016

This paper proposes a compensation algorithm for reducing a specific ripple component on synchronous reference frame phase locked loop (SRF-PLL) in grid-tied single-phase inverters. In general, SRF-PLL, which is based on all-pass filter to generate virtual voltage, is widely used to estimate the grid phase angle in a single-phase system. In reality, the estimated grid phase angle might be distorted because the phase difference between actual and virtual voltages is not 90 degrees. That is, the phase error is caused by the difference between cut-off frequency of all-pass filter and grid frequency under grid frequency variation. Therefore, the effects on phase angle and output current attributed to the phase error are mathematically analyzed in this paper. In addition, the proportional resonant (PR) controller is adapted to reduce the effects of phase error. The validity of the proposed algorithm is verified through several simulations and experiments.

• The Journal of Korean Physical Therapy
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• v.27 no.3
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• pp.154-158
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• 2015

Purpose: The purpose of this study was to propose a new reference point for measurement of the infrasternal angle and to investigate the intra- and inter-rater reliabilities of infrasternal angle measurement using photographs. Methods: Twenty-four healthy male college students participated as subjects in this study. Photographs were taken of subjects in two postures, one standing with the shoulders relaxed and one standing with the shoulders at $150^{\circ}$ abduction. All photographs were analyzed using Image J software. Raters used the photographs to measure the infrasternal angle between the xiphoid process, the medial margin of rib and navel on the right and left sides. The reliability of the infrasternal angle measurement was assessed by means of intraclass correlation coefficients [ICC (3,1)]. The level of statistical significance was set at p<0.05. Results: The intra- and inter-rater reliabilities of the infrasternal angle measurement for the right side at rest were excellent (ICC=0.866 and 0.813, respectively), as were those for the left side at rest (ICC=0.919 and 0.846, respectively). At $150^{\circ}$ shoulder abduction, the intra- and inter-rater reliabilities for measurement of the infrasternal angle on the right side were excellent (ICC=0.972 and 0.778, respectively), as were those for the left side (ICC=0.914 and 0.826, respectively). Conclusion: These findings suggest that this technique can be successfully used to measure the infrasternal angle, thus suggesting a new reference point for determining the length of the internal oblique and external oblique muscles in clinical situations.

• Transactions of the Society of Information Storage Systems
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• v.7 no.1
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• pp.1-6
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• 2011

A control method for the angle servo of reference beam during reading recoded data images of a holographic data storage system is presented. The recording scheme with angle offset is adopted in order to verify the proposed angle servo. Using this recording scheme, the angle error signal is generated and we can implement the angle servo. Experiments have been performed on recording and reading data images to compensate Bragg angle mismatch.

• Journal of Biosystems Engineering
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• v.14 no.3
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• pp.168-180
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• 1989

This study was attempted to develop the electronic-hydraulic hitch control system for position control of tractor plow and investigate the control performance of the system through experiments. Experiments were carried out to investigate the responses of the system to the step and sinusoidal inputs in position control. The effects of control mode, hydraulic flow rate, reference deadband, and proportional constant on control performance of the system were investigated. The following conclusions were derived from the study; 1. For the position control system operated on on-off control mode, positions of implement were controlled within ${\pm}0.73^{\circ}{\sim}{\pm}1.46^{\circ}$ in rockshaft angle to the reference position when the hydraulic flow rates were 5~15 l/min. For the position control system operated on PWM control mode, positions of implement were controlled within ${\pm}0.73^{\circ}$ to the reference position regardless of hydraulic flow rates. It means that the implement could be positioned more accurately to the reference position on PWM control mode than on on-off control mode. 2. As results of the frequency responses of the position control systems, no clear difference in control performance between on-off control and PWM control modes was found. As the hydraulic flow rates increased, the corner frequencies of amplitude attenuation and phase-angle change increased. It means that the control performance of the system could be improved as the hydraulic flow rate increases.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.23 no.6 s.165
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• pp.931-942
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• 1999

This paper develops a 3 DOF vehicle model which includes lateral, roll and yaw motion to study a 4WS vehicle. The model is used for the simulation of a 4WS vehicle behavior, and to derive a control algorithm for rear wheel steering. This paper uses a feedforward plus feedback control scheme to compute a rear wheel steering angle. The feedforward control scheme for computing the first rear wheel steering angle uses a gain which is acquired by multiplying a proper value on a gain to maintain a zero sideslip angle. The feedback control scheme for computing the second rear wheel steering angle uses fuzzy logic and model following control scheme. A linear 2 DOF model is used as a reference model for model following control, and is derived from the developed 3 DOF model by neglecting sprung mass roll motion. A reference state variable is yaw rate, and is computed using the linear 2 DOF model. J-turn and lane change maneuver simulation are performed to show the effectiveness of the developed control scheme. The simulation results show that the 4WS vehicle with the developed control scheme has much better performance in yaw rate, lateral acceleration, roll angle, and sideslip angle than the 2WS vehicle. Also, the results show that the performance of the developed control is close to the one of an optimal control which assumes all states are perfect.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1993.04b
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• pp.185-191
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• 1993

A flexible nanipulator can move in the high speed even with the small driving torque. The dynamic equations of flexible manipulator whichinclude 2 vibrationalmodes are derived using the clamped-free boundarycondition. Simulation results of the 6th order modelare well matched with experimental results. The hub angle of the flexible manipulator can be controlled without vibration of beam by the feedback of both hub angle and strain. The overshoot of the hub angle in the step resonse is reduced without sacrificing the rise time using the cycloidal function instead of the step function as the reference input.

• 제어로봇시스템학회:학술대회논문집
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• 1988.10a
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• pp.160-163
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• 1988

In this paper, the adaptive controller for the turret gun is discussed which uses model reference adaptive technique based on the Lyapunov direct method. Turret gun can be decomposed into two time-invariant SISO control systems. One is for the elevation angle control and the other is for the azimuth angle control under the assumption of independence each other. Thus we only consider here about the control loop for the elevation angle.

• Proceedings of the KIEE Conference
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• 1995.11a
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• pp.264-267
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• 1995

In indirect vector control, if the value or the rotor tine constant used in slip calculation is different from the actual rotor time constant because of the temperature rising and flux saturation level, model flux angle and actual flux angle is different so that the transient and steady state response is degraded. In this paper, flux deviation angle is calculated by using actual torque and reference torque, and this flux deviation angle is summed to slip angle, therefore rotor flux angle is always accurate and indirect vector control is satisfied.

• The Journal of Korean Academy of Prosthodontics
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• v.34 no.3
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• pp.448-456
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• 1996

The purpose of this study is to evaluate suitable anterior reference point similar to esthetic reference plane of the patient while transferring the suitable facebow. So those who live in Pusan with the normal occlusal relationship were chosen as subjects. The esthetic reference planes determined by the participants themselves and the superior reference line (anterior reference point) in Hanau & Denar articulator were compared with F-H plane in the standard lateral cephalogram. The results were as follows. 1. The angle between the esthetic reference plane and F-H plane was $2.81{\pm}5.7^{\circ}$. 2. The reference line, 43mm from Beyron point to the edge of the upper incisor, was the reference plane that had the closest paralleled relationship with the esthetic reference plane. 3. Transferring with ear piece type face-bow, the anterior reference point that showed the esthetic reference plane was 17mm below orbitale or 43mm above, the edge of the upper incisor.

• Journal of Veterinary Clinics
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• v.32 no.6
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• pp.481-485
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• 2015

The present study determined the normal reference ranges for overall pelvic limb alignment of small-breed dogs. For this purpose, 60 cadaveric canine pelvic limbs from normal small-breed dogs (Maltese, Poodle, Shih Tzu, Yorkshire Terrier). A frontal full-limb radiograph of each pelvic limb was obtained, and mechanical tibiofemoral angle (mTFA), mechanical metatarsotibial angle (mMTTA), mechanical axis-femur angle (MAFA), and mechanical axis-metatarsus angle (MAMTA) were measured from each radiograph, along with mechanical deviation of the stifle (SMAD) and tarsal joints (TMAD). The 95% CI for radiographic values of all pelvic limbs were mTFA, 5.7-7.4; mMTTA, $-2.2--0.8^{\circ}$; MAFA, $3.5-4.5^{\circ}$; MAMTA, 1.0-2.0; SMAD, 2.1-2.7%; TMAD, 0.5-1.0%. There values varied among the breeds, except for mTFA. The reference ranges can be used for diagnosing pelvic limb deformities in small-breed dogs and for planning corrective osteotomies.