2006 Graduate Catalog and 2005 Annual R & D Report - Sirindhorn ...

2006 Graduate Catalog and 2005 Annual R & D Report
Sirindhorn International Institute of Technology (SIIT)
Research Interests:
Phase Noise Models
Because of an exponential growth in wireless
communication, demand for the frequency channels
in mobile communication application is increasing,
which in turn, imposes more stringent requirements
on phase noise of circuits. Oscillator phase noise is
an essential parameter that limits the performances of
many modern telecommunication systems because
introducing even small noise into the circuit leads to
dramatic changes in its frequency spectrum and
timing properties. Phase and frequency fluctuations
have been the subject of numerous studies both
experimentally and theoretically.
Open-Ended Coaxial Line Microwave Sensor
Open-ended coaxial lines have been used as
electromagnetic sensors or probes in various
industrial and scientific applications. This includes invivo
characterization of biological media,
nondestructive measurements of materials, and noncontact
testing of disbands in composites. In these
applications, a radio frequency or microwave signal
excites the probe that is placed against the sample
medium. An echo signal received by the coaxial
sensor carries the characteristics of the sample
material. Therefore, the reflection coefficient (or
aperture admittance) at the sensor can be monitored
to extract the sample characteristics. Hence, the
characterization process requires a suitable electrical
model of the coaxial sensor in contact with the
sample.
Transformation of Transistor’s S-parameters
Manufacturers generally supply the data sheets of
transistors containing S-parameters with respect to
the emitter (or the source). In other words, the
transistor is considered as a two-port device with
common emitter (or common source) configuration.
However, the design engineers may want to use other
configurations of the transistor for certain circuits.
Hence, the transformation of S-parameters of the
transistor is needed. Feedback networks can be
conveniently designed to obtain the desired device
behavior.
Dr. Issarachai Ngamroo
Associate Professor
B.Eng. in Electrical Engineering, King Mongkut's Institute of Technology Ladkrabang (KMITL), Thailand
M.Eng. in Electrical Engineering, Osaka University, Japan
Ph.D. in Electrical Engineering, Osaka University, Japan
Areas of Specialization: Power system stability, Dynamics and control, FACTS applications, Robust control
application to power system stabilization.
Research Interests:
Wide Area Monitoring of Power System
Oscillations based on Synchronized Phasor
Measurement Units Developed in the Thailand
Power System
Due to a longitudinal structure of an interconnected
power system among northern, central and southern
areas of Thailand, there are possibilities of
occurrence of various oscillation modes such as interarea
oscillations, local generator oscillations, etc.
Such wide-area oscillations, however, have rarely
been observed between both regions. This study
focuses on a global monitoring system of power
system oscillations by using the synchronized phasor
measurement unit (PMU) of 220 volts demand side
outlets, which are located at Thammasat University,
Prince of Songkla University and Chiang Mai
University. Phasor measurements are synchronized
by the global positioning system and measured data
are transmitted via internet. By applying signal
processing techniques such as Fast Fourier
Transform and Wavelet Transform, analyzed results
of power system oscillation characteristics based on
PMU data can be carried out.
Robust Design of Power System Damping
Controllers
In interconnected-power systems, variations in
system configuration due to unpredictable
disturbances as well as nonlinear characteristics of
power systems cause several system uncertainties.
Under these situations, high robustness of power
system damping controllers is significantly desired.
This research takes advantages of robust control
theories such as H∞ control, variable structure
control, fuzzy control and optimization techniques,
etc., to design robust damping controllers of FACTS
devices, power system stabilizers, etc.
Dr. Pichai Jintakosonwit
Lecturer
B.Eng. in Electrical Engineering, King Mongkut's Institute of Technology Ladkrabang (KMITL), Thailand
M.Eng. in Electrical Engineering, Okayama University, Japan
Ph.D. in Electrical Engineering, Tokyo Institute of Technology, Japan
Areas of Specialization: Electric power quality, Active power filters, Dynamic voltage restorers.
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