• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1998.06a
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• pp.55-58
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• 1998

Recently, neural networks with self-adaptability like human brain have attracted much attention. It is desirable for the neuron-function to be implemented by exclusive hardware system on account of huge quantity in calculation. We have proposed a novel neuro-device composed of a MFSFET(ferroelectric gate FET) and oscillation circuit with CUJT(complimentary unijuction transistor) and PUT(programmable unijuction transistor). However, it is difficult to preserve ferroelectricity on Si due to existence of interfacial traps and/or interdiffusion of the constitutent elements, although there are a few reports on good MFS devices. In this paper, we have simulated CUJT and PUT devices instead of fabricating them and composed oscillation circuit. Finally, we have resented, as an approach to the MFSFET neuron circuit, adaptive learning function and characterized the elementary operation properties of the pulse oscillation circuit.

• Proceedings of the KIEE Conference
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• 1996.07b
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• pp.658-660
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• 1996

This paper prescribe the effects of SVC & TCSC in multi-machine power system. EMTP models of two FACTS controllers are proposed to analysis the basic characteristics of SVC & TCSC and the control signal of TCR is determined by rms value which was measured in system. The oscillation model of generator is proposed to analysis the damping effect and the most effective location of TCSC in multi-machine power system is identified by the residues associated with the natural oscillation modes. The 3 generator-9 bus model system is used to demonstrate the applicability of the proposed model.

• Proceedings of the Korean Nuclear Society Conference
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• 1997.05a
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• pp.90-95
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• 1997

In this work, linear dynamics of a circulating fluid-fueled subcritical reactor system with temperature feedback and external neutron source was modeled and examined. In a circulating fluid-fuel system, the stable region is slightly moved by a circulation fluid effect. The effects of subcriticality and temperature feedback coefficient on the reactor stability were tested by calculating frequency response of neutron density originated from reactivity perturbation or external source oscillation of system. The amplitude transfer function has a different shape near subcritical region due to the exponential term in the transfer function. The results of the study show that at a slightly subcritical region, low frequency oscillation in accelerator current or reactivity can be amplified depending on the temperature feedback. However, as the subcriticality increases, the oscillation becomes negligible regardless of the magnitude of the temperature feedback coefficient.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.55 no.1
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• pp.13-17
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• 2006

In this paper, the RCF(Resistive Companion Form) analysis method which is used to analyze small signal stability problems of non-continuous systems including switching devices. The RCF analysis method is mathematically rigorous and computes eigenvalue of the system periodic transition matrix based on discrete system analysis method. As an effect of switching operations, the eigenvalues of the systems are changed and newly unstable oscillation modes may be occurred. As an illustrating example, the oscillation modes of the system with different switching time intervals are computed exactly by the RCF analysis method and the results show that ON/OFF time intervals of switching equipments are important factors to make the system stable or unstable. This result shows that the RCF analysis method is very powerful to analyze small signal stability problems of power systems including switching devices such as FACTS equipments.

• Proceedings of the KIEE Conference
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• 2003.07a
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• pp.230-233
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• 2003

This paper describes the design of torsional oscillation controller in HVDC system using the universal SSR eigenvalue program. The suggested design procedures consist of three steps. Fist step is to identify the characteristics of AC system with torsional modes and HVDC system; then, to determine the control parameters of the suggested torsional oscillation controller (SSRStab) to compensate the phasor lagging due to rectifier controller. Finally, using time-domain simulation program verifies the designed parameters and determine the appropriate gain. The suggested method is simple to tune the parameters and effective to damp the least stable torsional oscillation mode.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.54 no.3
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• pp.122-132
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• 2005

This paper presents a novel approach based on Prony method to analysis of small signal stability in power system. Prony method is a valuable tool in identifying transfer function and estimating the modal parameter of power system oscillation from measured or computed discrete time signal. This paper define the relative residue of time signal and propose the condition to select low frequency oscillation in each generator. This paper describes the application results of proposed algorithm with respect to KEPCO systems. Simulation results show that the proposed algorithm can be used as another tools of power systems analysis.

• Proceedings of the KIEE Conference
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• 2005.07a
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• pp.492-494
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• 2005

In this paper, RCF analysis method which is very powerful to analyze non-continuous systems with switching elements is applied to small signal stability problems. As an effect of switching operations, the eigenvalues of system can be changed and newly unstable oscillation modes may be occurred. Also, changing the ON/OFF time intervals of switching equipments may make the system stable or unstable. As an illustrating example, the oscillation modes of system with different switching time intervals are computed by RCF analysis method.

• Proceedings of the KIEE Conference
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• 2006.07a
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• pp.12-13
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• 2006

In this paper, RCF(Resistive Companion Form) analysis method which is used to analyze small signal stability problems of non-continuous systems including switching device. The RCF analysis method are applied to the power systems with the thyristor controled FACTS equipments such as TCSC. As a result of simulation, the RCF method is very powerful to calculate the oscillation modes exactly after the switching operations, and useful to analyze the small signal stability of power systems with switching devices such as FACTS equipments. As an applicable example of the RCF method in power system, the one machine infinite bus system including TCSC at generator terminal bus is investigated and the results proved that variations of oscillation modes after periodic switching operations of TCSC can be calculated exactly.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.34 no.4
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• pp.399-408
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• 2010

The characteristics of lifted laminar propane flames diluted with nitrogen have been investigated experimentally to elucidate self-excitation and the effects of flame curvature. Flame oscillation modes are classified as follows: oscillation induced by heat loss, a combination of oscillations induced by heat loss and buoyancy, and a combination of the oscillations induced by heat loss and diffusive thermal instability. It is shown that the oscillation induced only by heat loss is not relevant to the diffusive thermal instability and hydrodynamic instability caused by buoyancy; this oscillation is observed under all lift-off flame conditions irrespective of the fuel Lewis number. These experimental evidences are displayed through the analysis of the power spectrum for the temporal variation of lift-off height. The possible mechanism of the oscillation induced by heat loss is also discussed.

• Journal of electromagnetic engineering and science
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• v.12 no.4
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• pp.227-233
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• 2012

This paper describes a novel and compact biosensing platform using an RF active system. The proposed sensing system is based on the oscillation frequency deviation due to the biomolecular binding mechanism on a resonator. The impedance variation of the resonator, which is caused by a specific biomolecular interaction results in a corresponding change in the oscillation frequency of the oscillator so that this change is used for the discrimination of the biomolecular binding, along with concentration variation. Also, a Surface Acoustic Wave (SAW) filter is utilized in order to enhance the biosensing performance of our system. Because the oscillator operates at the skirt frequency range of the SAW filter, a small amount of oscillation frequency deviation is transformed into a large variation in the output amplitude. Next, a power detector is used to detect the amplitude variation and convert it to DC voltage. It was also found that the frequency response of the biosensing system changes linearly with three streptavidin concentrations. Therefore, we expect that the proposed RF biosensing system can be applied to bio/medical applications capable of detecting a nano-sized biomolecular interaction.