• Proceedings of the KIEE Conference
• /
• 2005.05a
• /
• pp.141-143
• /
• 2005

An unknown linear time invariant plant with asymmetric oscillation in the output such as a static load disturbance. A saturation function nonlinear element is used to find the one point information in the frequency domain. An asymmetric self-oscillation caused by such as a static load disturbance saturation function feedback is analyzed. a new method to tune a PID controller based on the analysis is proposed in the presence of asymmetric oscillation. The proposed method does not require the knowledge of plant d.c. gain with an asymmetric oscillation in the plant output.

• Journal of the Korean Society of Combustion
• /
• v.6 no.2
• /
• pp.8-14
• /
• 2001

The effects of unsteady combustion are experimentally studied using forced pulsating mixture supply. It was shown that unsteady combustion used in this experiment plays an important role in controlling self-excited combustion oscillations. It may also have desirable performances, from a practical point of view, such as high combustion load, augmented heat transfer, reduced pollutant emissions and so on. We examined the characteristics of unsteady combustion driven by forced pulsating mixture supply in a small duct-combustor with a rearward-facing step. Further, we found its influence on the onset of self-excited combustion oscillations, the possibility of suppressing self-excited combustion oscillations and the reason why the self-excited combustion oscillation was suppressed using the forced pulsating mixture supply, comparing with the steady mixture supply.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.21 no.8
• /
• pp.1-9
• /
• 2007

Characteristics of electrodeless lamp as a load of the ballast are different compared to normal fluorescent lamp because the lame includes an inductance due to coupling magnetics for inductive discharging process. This increased parameter makes the development of self-oscillation type ballast more complex and time consuming. Practical simulation method for an easy design of self-oscillation type ballast especially for Endura lamp, is presented by using a model and various analysis of simulation. Results of experiment are given for a verification of proposed method.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.14 no.3
• /
• pp.220-227
• /
• 2009

A self oscillation DC/DC converter which has a very desirable characteristics of the high input-output voltage conversion ratio for high voltage DC power supply applications is proposed in this paper. The proposed converter is composed of one power switch, one inductor, several capacitors and diodes. Compared with conventional high-voltage DC/DC converters, it performs the high- voltage power conversion using the inductor instead of the bulky step-up transformer. Therefore, it can reduce the size of magnetic device and save the cost. Moreover, since it needs no control IC by using self oscillation circuit and has lower voltage stress on output diodes, it features a lower cost, simpler structure and more improved performance. Finally, a comparative analysis and experimental results are presented to show the validity of the proposed converter.

• Journal of Korean Vacuum Science & Technology
• /
• v.6 no.1
• /
• pp.43-45
• /
• 2002

We have theoretically investigated steady-state carrier transport and current self-oscillation in negative-effective-mass (NEM) p$\^$+/pp$\^$+/diodes. The current self-oscillation here is a result of the formation and traveling of electric field domains in the p base having a NEM. The dependence of self-oscillating frequency on the applied dc voltage is obtained by detailed numerical simulations. In the calculations, we have considered the scatterings by carrier-impurity, carrier-acoustic phonon, carrier-polar-phonon, and carrier-nonpolar-phonon-hole interactions . This kind of NEM oscillator allows us to reach a current oscillation with terahertz frequency, thus it may be used as a broadband source of terahertz radiation.

• JSTS:Journal of Semiconductor Technology and Science
• /
• v.2 no.3
• /
• pp.226-232
• /
• 2002

This paper explains a technique to improve the fault coverage of oscillation-test [1-5] for linear analog circuits. The transient behavior of the virtual ground is monitored during oscillation to extract information of the circuit. The limitation of the oscillation-test is analyzed, and an efficient signature analysis technique is proposed to maximize the fault coverage. The experimental result proves that the parametric fault coverage can be significantly increased by the proposed technique.

• ETRI Journal
• /
• v.32 no.1
• /
• pp.154-156
• /
• 2010

Oscillation-based testing of analog-to-digital converters represents a viable option for low-cost built-in self-testing in mixed-signal design. While numerous papers have addressed implementation issues, little attention has been paid to the measurement accuracy. In this letter, we highlight an inherent measurement uncertainty which has to be considered when deriving the parameters from the oscillation frequency.

• Environmental Engineering Research
• /
• v.9 no.6
• /
• pp.256-268
• /
• 2004

• Journal of the Institute of Electronics Engineers of Korea SD
• /
• v.41 no.12
• /
• pp.51-57
• /
• 2004

A simple fiber length measurement technique has been demonstrated by using a self-seeding laser oscillation of a Fabry-Perot laser diode. We induced a self-seeding laser oscillation through a closed-loop by adjusting the modulation frequency of a Fabry-Peort laser diode when the output optical pulse of the laser reinjected into the laser after passing through the closed-loop. The length of a fiber-under-test was calculated from the difference between my two modulation frequencies at which self-seeding laser oscillation occurs at a specific mode. We have experimentally confirmed the technique for various fiber lengths from 0.1 km to 75 km. The relative error between the measurement result of the proposed technique and that of a commercial instrument was less than 0.24 %. The repeatability of the proposed technique was better than 0.1 %.

• Atmosphere
• /
• v.21 no.3
• /
• pp.221-228
• /
• 2011

The nonlinear characteristics of summer monsoon intraseasonal oscillation (ISO) in precipitation, which is manifested as fluctuations in convection and circulation, is one of the major difficulty on the prediction of East Asian summer monsoon (EASM). The present study aims to identify the spatial distribution and time evolution of nonlinear phases of monsoon ISO. In order to classify the different phases of monsoon ISO, Self-Organizing Map(SOM) known as a nonlinear pattern recognition technique is used. SOM has a great attractiveness detecting self-similarity among data elements by grouping and clustering such self-similar components. The four important patterns are demonstrated as Meiyu-Baiu, Changma, post-Changma, and dry-spell modes. It is found that SOM well captured the formation of East Asian monsoon trough during early summer and its northward migration together with enhanced convection over subtropical western Pacific and regionally intensive precipitation including Meiyu, Changma and Baiu. The classification of fundamental large scale spatial pattern and evolutionary history of nonlinear phases of monsoon ISO provides the source of predictability for extended-range forecast of summer precipitation.