• Proceedings of the KIEE Conference
• /
• 2002.07d
• /
• pp.2138-2139
• /
• 2002

In this paper we presents a speed controller for separately excited DC motor using adaptive backstepping technique. The motor was modeled in two local areas the first model is a linear one when speed is under base speed, the other is nonlinear one when field weakening is used to obtain the speed well above base speed. Then linear robust state feedback controller was designed for the linear model while adaptive backstepping controller was designed for the nonlinear model. The adaptive backstepping technique takes system nonlinearity into account in the control system design stage. The proposed controller is proved to be asymptotically stable by the Lyapunov stability theory and some simulations have been carried out to test.

• Proceedings of the KIEE Conference
• /
• 2000.07d
• /
• pp.2624-2626
• /
• 2000

The stabilization controls of coupled tank system and ball-beam system are difficult control tasks because of their high order time delay, nonlinearity and structural unstability. Fuhermore, a series of classical methods such as a conventional PID and a full state feedback controller(FSFC) based on the local linearizations have narrow stabilizable regions. Therefore, in this paper, in order to stabilize two representative nonlinear system mentioned above, a Sliding Mode Controller based on a Real Variable Elitist Genetic Algorithm(RVEGA SMC) was proposed.

• Proceedings of the KIEE Conference
• /
• 2000.07d
• /
• pp.2302-2304
• /
• 2000

This paper addresses a fuzzy controller for nonlinear systems control using a pole placement in a specified disk. In the method, we linearize a nonlinear plant about nominal operating points and represent it using TS fuzzy model and formulate the controller rules. A feedback control law for a local model is determined using a pole placement in a specified disk(${\alpha}$:center ${\gamma}$:radius} region so that the closed loop system is stable. A nonlinear system can be controlled by combining fuzzy controller with a pole placement scheme which can be used to modify the transient response such as damping ratio and overshoot. A stability of overall fuzzy control system is guaranteed in the Lyapunov sense. Finally, it is shown that the proposed method is feasible through a computer simulation.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.63 no.1
• /
• pp.156-161
• /
• 2014

With the proliferation of digital music, public's interest in music and desire to sing well are increasing. This paper presents the implementation of a tone correction system through a visualization of comparison between music and humming data. For this we extract MIDI note from music and humming data and then design a matching engine using DTW algorithm which is for robust matching results against local timing variation and inaccurate tempo. This system is expected to correct the user's wrong tone by visualization and feedback from the result.

• Proceedings of the KIEE Conference
• /
• 1993.07b
• /
• pp.806-808
• /
• 1993

New soft recovery drive which can alleviate the loss due to reverse recovery of diode is proposed. By using this drive, the reverse current of the diode is minimized and stabilized because there is inner local feedback loop between the turn-on current of the power MOSFET and the reverse recovery current of the diode. The loss and EMI noise can be considerably reduced in this way. Brief operational principle and experimental results are included to verify the usefulness.

• 제어로봇시스템학회:학술대회논문집
• /
• 2001.10a
• /
• pp.41.3-41
• /
• 2001

In this paper, we present a decentralized adaptive neural net(NN) controller for the transient stability and voltage regulation of a multimachine power system. First, an adaptively input-output linearizing controller using NN is designed to eliminate the nonlinearities and interactions between generators. Then, a robust control term which bounds terminal voltage to a neighborhood of the operating point within the desired value is introduced using only local information. In addition, we consider input saturation which exists in the SCR amplifier and prove that the stability of the overall closed-loop system is maintained regardless of the input saturation. The design procedure is tested on a two machine infinite bus power system.

• Journal of the Korean Institute of Telematics and Electronics
• /
• v.24 no.3
• /
• pp.413-419
• /
• 1987

In this paper, self-oscillating mixer is designed by small signal S-parameter and series feedback circuit. The input-output matching circuit is accomplished from double stub and additional matching stub. The self-oscillating mixer is oscillating itself and amplifies without any external local oscillator and an intermediate frequency amplifier, so it has advantages in its economical and system simplification. The experimental results show the maximum conversion gain 1.5d B and the noise figure 6.5d B at RF center frequency 4GHz and IF 1.1GHz` output oscillating power 4d Bm, efficiency 13.4%, stability -10MHz/V and -0.5MHz/\ulcornerC at oscillating frequency 5.1GHz.The rejection band loss characteristics in band pass filter and low pass filter are -40d B and -30d B, respectively.

• Educational Technology International
• /
• v.14 no.2
• /
• pp.215-228
• /
• 2013

In engineering education practical experiments is very important for each student, but due to the limitation of time and available resources such as laboratory equipment, space and instructors enough hands-on real experiments could not be provided to all students enrolled in the program throughout the academic year. In this sense web-based remote experiments through internet become a solution for engineering education and an emerging new paradigm for students and teachers. This paper presents the development of the web-based remote vibration experiment system for mechatronics education. Students can access this experimental equipment through an internet and conduct vibration experiment remotely without any restriction on time and place. IP address for data communication and web-service are assigned in local computer and then students receive experimental results and the captured pictures using network. The developed system provides real-time feedback of the tested results. Ubiquitous access to the system gained popularity from students.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.40 no.12
• /
• pp.2353-2362
• /
• 2015

In this paper, we employ the single channel full duplex radio for wireless local area network (WLAN) systems, and design digital interference cancellers using adaptive signal processing. When the full duplex scheme is used for WLAN systems with multiple transmit and receive antennas, some interference is caused through the feedback of transmit signals from multiple antennas. To remove the feedback interference, we derive the least mean square (LMS), normalized LMS (NLMS), and recursive least squares (RLS) algorithms based on adaptive signal processing techniques. In addition, we analyze the theoretical convergence of the proposed LMS and RLS methods. The channel capacity of full duplex radios increases by two times than that of half duplex radios, when the packet error rate (PER) performances for the two systems are identical. Through numerical simulations in WLAN systems, it is shown that the full duplex method with the proposed interference cancellers has a similar PER performance with the conventional half duplex transmission scheme.

• The Journal of Korean Obstetrics and Gynecology
• /
• v.20 no.2
• /
• pp.188-195
• /
• 2007

Purpose: The purpose of this study was to analyze current status of the web-sites dealing with oriental obstetrics & gynecology in the internet, and to evaluate their quality and confidence of health information. Methods: It was selected 54 local sites by searching for such key words as menstrual pain. The evaluation tool consisted of six major classification (Content, Authorship, Purpose, Functionality, Feedback and Privacy). Results: In the evaluation of web-sites, the lowest and the highest scores were 7 and 19 out of 26, and the average score was 13.94. The scores of Purpose, Content, Feedback were higher than the average, but the scores of Authorship, Functionality, Privacy were lower than the average. Conclusion: There is a need to develop a high-quality information about latest, confidence, authorship of documents, and to prevent a exposure of privacy.