• Journal of Biomedical Engineering Research
• /
• v.28 no.2
• /
• pp.294-299
• /
• 2007

For efficient and accurate diagnosis of ultrasound images, appropriate time gain compensation(TGC) and dynamic range(DR) control of ultrasound echo signals are important. TGC is used for compensating the attenuation of ultrasound echo signals along the depth, and DR controls the image contrast. In recent ultrasound systems, these two factors are automatically set by a system and/or manually adjusted by an operator to obtain the desired image quality on the screen. In this paper, we propose an algorithm to find the optimized parameter values far TGC and DR automatically. In TGC optimization, we determine the degree of attenuation compensation along the depth by dividing an image into vertical strips and reliably estimating the attenuation characteristic of ultrasound signals. For DR optimization, we define a novel cost function by properly using the characteristics of ultrasound images. We obtain experimental results by applying the proposed algorithm to a real ultrasound(US) imaging system. The results verify that the proposed algorithm automatically sets values of TGC and DR in real-time such that the subjective quality of the enhanced ultrasound images may be sufficiently high for efficient and accurate diagnosis.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.37 no.4A
• /
• pp.197-204
• /
• 2012

We propose a new scheme combining the compensation of HPA nonlinearity and the calibration of the path imperfections in the downlink OFDM smart antenna systems. We use a two term third-order polynomial (without second-order term) and the feedforward method for compensation and calibration to make each path of the antenna array have equal characteristics. Since the proposed scheme does not alter the base-band signal, it can be applied to the smart antenna system independently of the base-band signal processing section. The result of computer simulations shows that, with the addition of only one third-order term, the adverse nonlinear effects can be effectively compensated, and the those of linear imperfections can be calibrated as well.

• Journal of Digital Convergence
• /
• v.11 no.6
• /
• pp.137-142
• /
• 2013

Speech recognition system is input of inaccurate vocabulary by feature extraction case of recognition by appear result of unrecognized or similar phoneme recognized. Therefore, in this paper, we propose a speech recognition error correction method using phoneme similarity rate and reliability measures based on the characteristics of the phonemes. Phonemes similarity rate was phoneme of learning model obtained used MFCC and LPC feature extraction method, measured with reliability rate. Minimize the error to be unrecognized by measuring the rate of similar phonemes and reliability. Turned out to error speech in the process of speech recognition was error compensation performed. In this paper, the result of applying the proposed system showed a recognition rate of 98.3%, error compensation rate 95.5% in the speech recognition.

• Journal of the Institute of Electronics and Information Engineers
• /
• v.51 no.2
• /
• pp.163-167
• /
• 2014

To prove the vibration and speed error problems caused by the nonlinear friction characteristics and load variation of the hydraulic system, a PID speed controller and a load compensation controller for the hydraulic inverter-fed elevator are proposed. The load compensation controller is composed by the PI controller and the speed controller is composed by the PID controller. The P,I and D gains of the control parameters are obtained by the frequency response of system transfer function. The Effectiveness of the proposed controller are shown by experimental results, which the proposed controller yields robustness with load variations and stable and good speed and acceleration responses with less oscillations.

• Speech Sciences
• /
• v.15 no.3
• /
• pp.183-201
• /
• 2008

This study attempted to reveal the physiologic etiology or related factors associated with speech processing by comparing the compensation ability in speech motor control in children with and without articulation disorders. Subjects were 35 children with articulation disorder and 35 children without articulation disorder whose age ranged from 5 to 6 years. They were asked to rapidly repeat /$p^ha$/, /$t^ha$/, /$k^ha$/, /$p^hat^hak^ha$/ diadochokinetic movement while mandible was free and mandible was stabilized with bite block. The results showed that children with articulation disorder revealed significantly greater difference in elapsed time for diadochokinetic movement between mandible free and stabilized state compared to the without articulation disorder group. But the correlation between the percentage of consonants correct and the compensation ability in speech motor control in the articulation disorder group was irrelevant. These results point out to the fact that children with articulation disorder have poor compensation ability in speech motor control compared to the children without articulation disorder. On the other hand, the poor ability does not have any relation with the severity of articulation disorder. These results suggest either general or individual characteristics of children with articulation disorder.

• Journal of Advanced Navigation Technology
• /
• v.9 no.2
• /
• pp.140-146
• /
• 2005

In this paper, we proposed the frequency offset compensation algorithm and tracking algorithm which could improve the accumulated phase error for HDR-WPAN system. The proposed frequency offset compensation technique estimated each sample phase error by autocorrelation characteristics of CAZAC sequence, estimated phase error multiple each sample in a symbol, and finally compensated for the frequency offset. After frequency offset compensation using two steps, coarse and fine frequency offset, tracking algorithm have to use to compensate for the accumulated phase error. Because there is no pilot symbol in payload, more phase rotation occurred in received signal constellations due to the accumulated phase error as the payload length increase. Tracking algorithm compensates for a cumulative phase error ${\theta}$ between payload data.

• Proceedings of the KIPE Conference
• /
• 2005.07a
• /
• pp.8-10
• /
• 2005

In a general purpose inverter, a dead-time compensation strategy is very important for reducing torque ripples and acoustic noises of motors. However, in the case of small capacity inverter, the accurate dead-time compensation is hard to be obtained because a removal of the switching noise in a feedback current signal is difficult on condition of low-cost implementation. In this paper, the operation characteristics of the general purpose inverter applied the dead time compensation algorithm using an instantaneous back calculation of the phase angle of the current are presented.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.21 no.3
• /
• pp.223-228
• /
• 2010

In this paper, temperature compensation circuit for the X-band voltage controlled oscillator(VCO) is presented by using the temperature sensor with the OP-AMP circuit. The frequency drifting by the temperature could be compensated by applying the tuning voltage which include the linearly changing output voltage of the temperature sensor. As a result, the frequency variation is reduced to 6.6~4.4 MHzfrom the 71~73 MHz variation with the compensation circuit over -30~+$60^{\circ}C$ range, when VCO is operated in the frequency range of 9.95~10.05 GHz.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.22 no.2
• /
• pp.166-174
• /
• 2017

This study proposes a compensation method for the dead-time effects on a single-phase grid-connected inverter. Dead time should be considered in the pulse-width modulation gating signals to prevent the simultaneous conduction of switching devices, considering that a switching device has a finite switching time. Consequently, the output current of the grid-connected inverter contains odd-numbered harmonics because of the dead time and the nonlinear characteristics of the switching devices. The effects of dead time on output voltage and current are analyzed in this study. A new compensation algorithm based on second-order generalized integrator is also proposed to reduce the dead-time effect. Simulation and experimental results validate the effectiveness of the proposed compensation algorithm.

• The Korean Society of Law and Medicine
• /
• v.13 no.1
• /
• pp.295-329
• /
• 2012

A medical malpractice case requires special legal protection, considering its characteristics, such as seriousness and long term effects of its damages, medical information asymmetry between practitioners and patients, and difficulties in realization of liability. Taking the points above into consideration, Medical Malpractice Arbitration Act of 2012(MAA) has legislative intent to protect the rights of the injured from medical malpractice, while protecting the stability of medical practice by providing arbitration as an alternative dispute resolution. However, constitutional review is required for one new scheme of compensation for medical injuries during delivery, which is implemented in MAA of 2012, especially with regard to freedom to exercise occupation, property, equality under the Constitution. Two important aspects are 1. according to the law, absolute liability applies to compensation for damages during delivery without negligence of practitioners; and 2. the practitioner bears some portion of the cost, 30% in the law above. This article aims to analyze this new institution in various aspects of the Constitution, and, as a result, it does not comply with constitutional criteria.