• KSBB Journal
• /
• v.14 no.2
• /
• pp.198-204
• /
• 1999

Asymbiotic bacterium with highly effective toxins was isolated from entomopathogenic nematode Steinernema glaseri which has been widely used against various soil-inhabiting pests. The symbiont of S. glaseri was identified as Xenorhabdus nematophilus sp. by using several biochemical and physiological tests. When this strain was released into the hemolymph of insect larva, it produced highly toxic substances and killed the larva within 2 days. Two colony forms that differed n some biochemical characteristics were observed when cultures in vitro. Phase l colonies were mucid and difficult to be dispersed in liquid. Phase II was not mucoid and was easily dispersed in liquid. It did not adsorb neutral red or bromothymol blue. Rod-shaped cell size was highly variable between two phases, ranging 2-10 ${\mu}{\textrm}{m}$. It was also found that only infective-stage nematodes can carry only primary-phase Xenorhabdus in their intestine.

• Journal of Power Electronics
• /
• v.4 no.3
• /
• pp.169-179
• /
• 2004

This paper presents the steady-state analysis of the three-phase self-excited induction generator (SEIG). The three-phase SEIG with a squirrel cage rotor is driven by a variable-speed prime mover (VSPM) or a constant-speed prime mover (CSPM) such as a wind turbine or a micro gas turbine. Furthermore, a PI closed-loop feedback voltage regulation scheme of the three-phase SEIG driven by a VSPM on the basis of the static VAR compensator (SVC) is designed and evaluated for the stand-alone AC and DC power applications. The simulation and experimental results prove the practical effectiveness of the additional SVC with the PI controller-based feedback loop in terms of its fast responses and high performances

• The Transactions of the Korean Institute of Electrical Engineers
• /
• v.36 no.12
• /
• pp.856-867
• /
• 1987

Microprocessor control of power-electronic equipment offers the possibility of improvements in manufacture, realizability, maintenance and servicing, and increased control flexibility. In this paper, simple microprocessor control with a view to approximating the polynomial equations which govern the commutation angles was consisdered. The theoretical analysis of this principle which govern the commutaton of power switches in order to cancel any predetermined harmonics and vary the fundamental rms voltage of the inverter output is described. Also the spectrum and harmonics were analyzed by HP-1000 computer. Practical aspect of the realization of a voltage controller based on a microprocessor and a suitable system for variable frequency inverter were also presented. The experimental test has been carried out on a Z-80 microcomputer and a single phase transistor inverter. The various results show the feasibility of obtainintg practically a single phase and a three phase inverter waveforms, which are highly desirable in most inverter applications.

• Journal of Institute of Control, Robotics and Systems
• /
• v.11 no.11
• /
• pp.895-900
• /
• 2005

We derive a linear matrix inequality(LMI) condition guaranteeing that any invariant zeros of a triple (A, B, C) lie in the open left half plane of the complex plane, i.e. $C(sI-A)^{-1}B$ is minimum phase. The LMI condition is equivalent to a certain constrained Lyapunov matrix equation which can be found in many results relating to stability analysis or control design. We show that the LMI condition can be used to simplify various control engineering problems such as a dynamic output feedback control problem, a variable structure static output feedback control problem, and a nonlinear system observer design problem. Finally, we give some numerical examples.

• The Journal of the Korea institute of electronic communication sciences
• /
• v.9 no.12
• /
• pp.1441-1446
• /
• 2014

Love which is one of the emotional of mankind, has been studied in sociology and psychology as a matter of grate concern. In this paper we propose a modified romantic behaviors by using basic the love equation of Romeo and Juliet. We represent the behaviors using time series and phase portrait when we vary the parameter in the modified love equation. Also we analyze the behavior's relation by using time series and phase portraits when external force applied as the third person between Romeo and Juliet.

• Journal of Information Display
• /
• v.10 no.1
• /
• pp.19-23
• /
• 2009

In this paper, we review the proposed liquid crystal display (LCD) with a tunable viewing angle consisting of a conventional liquid crystal display (LCD) panel and a thermally variable retardation layer (TVRL) characterized by uniformly aligned LC film with transparent indium-tin-oxide electrodes for Joule heating. In the TVRL, nematic phase is transitioned into isotropic by Joule heating. The numerical calculation showed that the intrinsic wide viewing angle was achieved at the isotropic phase of the TVRL by Joule heating, whereas the narrow viewing angle was obtained at the nematic phase of the TVRL. The simulated and experimental results of the proposed LCD show continuous and symmetrical viewing angle characteristics by tuning the retardation of TVRL using Joule heating. The structure of the viewing angle control proposed here is adoptable to all LCD modes with wide viewing angle characteristics.

• Journal of the Korean Institute of Telematics and Electronics A
• /
• v.31A no.5
• /
• pp.68-75
• /
• 1994

A new Predistortor that is designed using Feedforward type is proposed to overcome the nonlinearity of HPA (High Power Amplifier). HPA has the nonlinearity of the gain compression and phase distorton, so digital communication system of multi-carrier TDMA needs the linear RF transmitter. Using IMD (Intermodulation Distortion) of drive amplifier, as Feedforward type, the inverse IMD is coupled to the main loop with variable attenuators, phase shifters, and sub-amplifiers well designed. At the input of main amplifier, the over-coupled IMD surpresses the main amplifier 's IMD. Adjusting the level and phase of IMD at the sub loop, C/I of HPA is better than before correction.

• Journal of Mechanical Science and Technology
• /
• v.17 no.12
• /
• pp.1922-1927
• /
• 2003

Nonlinear normal mode (NNM) vibration, in a nonlinear dual mass Hamiltonian system, which has 6$\^$th/ order homogeneous polynomial as a nonlinear term, is studied in this paper. The existence, bifurcation, and the orbital stability of periodic motions are to be studied in the phase space. In order to find the analytic expression of the invariant curves in the Poincare Map, which is a mapping of a phase trajectory onto 2 dimensional surface in 4 dimensional phase space, Whittaker's Adelphic Integral, instead of the direct integration of the equations of motion or the Birkhoff-Gustavson (B-G) canonical transformation, is derived for small value of energy. It is revealed that the integral of motion by Adelphic Integral is essentially consistent with the one obtained from the B-G transformation method. The resulting expression of the invariant curves can be used for analyzing the behavior of NNM vibration in the Poincare Map.

• Proceedings of the KIEE Conference
• /
• 2007.04a
• /
• pp.110-112
• /
• 2007

Output voltage waves of a DC/AC inverter system are likely to be distorted if variable loads e.g. motors or rectifiers exist in the output terminal. This paper designs a disturbance observer-based PI controller for a single-phase inverter system that is robust against load changes. In this paper, we regard the output voltage changes due to various loads as disturbances of the control system, Then we design a disturbance observer for estimation of the disturbances caused by the load current and any other error sources (such as parameter uncertainties and model mismatches etc.). In order to test the performance of the proposed control law, simulation studies are carried out for a single-phase inverter system using SimPowerSystems of Matlab Simulink. Compared to a simple PI control, the disturbance observer-based controller shows enhanced performance in transient responses for step load changes.

• Journal of Power Electronics
• /
• v.9 no.2
• /
• pp.198-206
• /
• 2009

An algorithm is developed that enables a single-phase matrix converter (SPMC) to perform functions of a generalized single phase power electronics converter such as acting as a frequency changer, rectifier, inverter, and chopper. This reduces the need for new converter hardware. The algorithm is implemented first on computer simulation software Orcad Capture CIS version 9.1. Simulation results are presented for five types of converters with a control input variable that decides the 1) type of converter and 2) type of output waveform. The simulated results verify the working and operation of a generalized converter based on SPMC. Simulated results are verified with experimental results. Hardware design is obtained using readily available ICs and other components. The trigger circuit has been tested qualitatively by observing waveforms on CRO. The operation of the proposed system has been found to be satisfactory.