• Journal of KIEE
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• v.11 no.1
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• pp.62-68
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• 2001

In this paper it is proposed an advanced modified sliding mode control of a rotor field oriented control of induction motor. The application of this unconventional control has very good results, such as disturbance rejection and nice dynamic properties. Stability can be guaranteed even in the worst situation. A conventional "sliding mode" controller is characterised by fast switching control signal, which causes the chattering of the drive system. To overcome this problem, a modified law is used, by introducing a hysteresis band and a continuous control, which modifies the conventional law. The control is accomplished with dual TMS320C44 floating-point digital signal processor. The validity of the proposed method was verified by experiment on the propulsion system simulator, used for the development of Korean High-Speed Railway Train(KHSRT).in(KHSRT).

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.46 no.2
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• pp.182-188
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• 2018

In order to increase the robustness of the uplink for UAS(Unmanned Aerial System), we propose a jamming signal rejection algorithm. In the UAS datalink system, DSSS (direct sequence spread spectrum) is used to reduce the radio noise or jamming signal. In general, jamming signals below the spreading gain are recoverable but the signals beyond the spreading gain can not be recovered. In this paper, these jamming signals beyond spreading gain are detected using the threshold detector in the spectrum area then, generate the estimated signals from the sine wave generator. Finally, we obtain the desired signal to remove jamming signals from the received signals. The proposed scheme can eliminate jamming signals while minimizing the hardware complexity and the original signal loss.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.44 no.2 s.314
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• pp.1-11
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• 2007

H.264/AVC uses variable block sizes to achieve significant coding gain. It has 7 different coding modes having different motion compensation block sizes in Inter slice, and 2 different intra prediction modes in Intra slice. This fine-tuned new coding feature has achieved far more significant coding gain compared with previous video coding standards. However, extremely high computational complexity is required when rate-distortion optimization (RDO) algorithm is used. This computational complexity is a major problem in implementing real-time H.264/AVC encoder on computationally constrained devices. Therefore, there is a clear need for complexity reduction algorithm of H.264/AVC such as fast mode decision. In this paper, we propose a fast mode decision with early $P8\times8$ mode rejection based on block size activity using large block history map (LBHM). Simulation results show that without any meaningful degradation, the proposed method reduces whole encoding time on average by 53%. Also the hybrid usage of the proposed method and the early SKIP mode decision in H.264/AVC reference model reduces whole encoding time by 63% on average.

• Journal of the Korea Convergence Society
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• v.9 no.1
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• pp.465-471
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• 2018

Recently, biometric technology has begun to be used as a fusion of IT technology and financial system. Using this biometric technology, FIDO(Fast Identity Online) technology, Samsung and Apple started Samsung Pay and Apple Pay service. FIDO authentication technology replaces existing authentication methods such as passwords. Among the biometric technologies, fingerprint recognition technology is attracting attention because it can minimize the device and user rejection at a relatively low price. However, fingerprint information has a limited number of users and it can not be reused if fingerprint information is leaked by an external attacker. Therefore, in this paper, we propose a method to authenticate a user using EEG signal which is one of biometrics technologies. W propose a method to use EEG signal measurement value in FIDO system by using convenience channel by using short channel EEG device. And propose a method to utilize EEG signal when the user recognizes a specific entity by measuring the EEG signal before and after recognizing a specific entity.

• International Journal of Control, Automation, and Systems
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• v.5 no.2
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• pp.161-169
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• 2007

The PLL equivalent augmented system incorporated with state feedback is proposed in this paper. The optimal value of filter time constant of loop filter in the phase-locked loop control system and the optimal state feedback gain designed by using linear quadratic regulator approach are derived. This approach allows the PLL control system to employ the large value of the phase-frequency gain $K_d$ and voltage control oscillator gain $K_o$. In designing, the structure of phase-locked loop control system will be rearranged to be a phase-locked loop equivalent augmented system by including the structure of loop filter into the process and by considering the voltage control oscillator as an additional integrator. The designed controller consisting of state feedback gain matrix K and integral gain $k_1$ is an optimal controller. The integral gain $k_1$ related to weighting matrices q and R will be an optimal value for assigning the filter time constant of loop filter. The experimental results in controlling the second-order lag pressure process using two types of loop filters show that the system response is fast without steady-state error, the output disturbance effect rejection is fast and the tracking to step changes is good.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.2240-2245
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• 2003

In this paper, the controller design by coefficient diagram method (CDM) for controlling the trolley position, load-swing angle and hoisting rope length of the overhead crane system simultaneously is proposed. The overhead crane system is a MIMO system consisting of two inputs and three outputs. Its mathematical model is nonlinear with coupling characteristics. This nonlinear model can be approximated to obtain a linear model where the first input mainly affects the trolley position and the load-swing angle while the second input mainly affects the hoisting rope length. In order to utilize the CDM concept for assigning the controllers, namely PID, PD and PI controllers separately, the model is approximated to be three transfer functions in accordance with trolley position, the load-swing angle and the hoisting rope length controls respectively. The satisfied performances of the overhead crane system controlled by the these controllers and fast rejection of the disturbance effect occurred at the trolley position are shown by simulation and experimental results.

• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.520-523
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• 2004

A phase-locked loop control system designed by using the linear quadratic regulator approach is presented in this paper. The system thus designed is optimal system when system is in locked state and the parameter value of loop filter which is an active PI filter can be obtained easily. By considering the structure of loop filter of phase-locked loop is included in the process to be controlled, a type 1 servo system can be constructed when voltage control oscillator is considered as an integrator. The integral gain of the proposed system obtained by linear quadratic regulator approach can be used as an optimal value to design the parameter of loop filter. The implemented result in controlling the second-order lag pressure process by using the proposed scheme show that the system response is fast with no overshoot and no steady-state error. Furthermore, the experimental results are also shown in term of output disturbance effect rejection, tracking and process parameter changed.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.15 no.7
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• pp.706-712
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• 2004

This paper presents the design technique of output multiplexer(OMUX) for the Ka-band satellite transponder. Output multiplexer consists of low-pass filter(LPF), channel filter and manifold. Channel filters adopt dual-mode technique in design for mass and volume reduction and frequency response of channel filters is 4-pole elliptic response for high frequency selectivity. w-pass filters are designed to be of 13th order corrugated type for high rejection characteristic over reception band of satellite transponder. After initial design of channel filters and manifold, we optimized only a few design parameters for fast and easy optimization instead of optimizing all the design parameter. Measured results of a realized output umltiplexer for Ka-band satellite transponder show good agreement with the computed ones.

• Journal of the Korea Institute of Military Science and Technology
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• v.12 no.4
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• pp.540-547
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• 2009

In the near future, military robots are likely to be substituted for military personnel in the field of battle. The power system of a legged robot is considerably more complex than the one used for a land vehicle because of the coordination and stability issues due to the large number of degree of freedom. In this paper, a servovalve-piston combination system for a straight-line motion of robot leg is modeled as three degree of freedom based on double inputs and single output transfer function. The output is the displacement of piston from neutral. The inputs are valve displacement from neutral and arbitrary load force in this system. LQR(Linear Quadratic Regulator) technique is applied in order to achieve robust stability and fast responses of the system. The Kalman filter loop, rejection of disturbance and noise, riccati equation, filter gain matrix, and frequency domain equality are analyzed and designed.

• Proceedings of the KIPE Conference
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• 2002.07a
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• pp.455-458
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• 2002

A control of the body posture and movement is maintained by the vestibular system, vision, and proprioceptors. Especially, vestibular system has a very important function that controls the eye movement through vestibuloocular reflex and contraction of skeletal muscles through vestibulospinal reflex. However, postural disturbance caused by loss of vestibular function results in nausea, vomiting, vertigo and loss of craving for life. Lose of vestibular function leads to abnormal reflex of eye movements named nystagmus. Analysis of the nystagmus is needed to diagnose the vertigo, which is performed by means of electronystagmography (ENG). The purpose of this study is to develop a computerized system for data processing and an algorithm for the automatic evaluation of the slow component velocity (SCV) of nystagmus Induced by optokinetic(OKN) stimulation system. A new algorithm using recursive least square method (RLSM) to detect SCV of nystagmus is suggested in this paper. This method allows a fast and precise evaluation of the nystagmus, through artifact rejection techniques. The results are depicted in this paper.