• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.19 no.6
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• pp.100-108
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• 2005

In this paper deals with the frequency control of the HVDC scheme linking Haenam to Cheju Island. The primary aim of the study is to develop and evaluate a new frequency control that can be employed without having to utilise the existing Synchronous Compensators(Gas Turbines). Transient condition studies are performed utilising the detailed control strategies for the HVDC link, implemented in PSCAD/EMTDC. Study cases are completed involving synchronous compensators trip and load ripping events and study plots presented. It is demonstrated that the existing frequency measurement can be replaced by one derived from the AC network alone, incorporated into a new frequency control algorithm and gives effective frequency control and dynamic performance.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.14 no.2
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• pp.46-51
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• 2000

The generation of the intensive ultrasonic waves depend mainly on the energy conversion efficiency depending on high frequency oscillation of the generator and the control performance of stable output depending on load variation, respectively. In this dissertation, a new configuration of ultrasonic generator is specially proposed and designed for improving both efficiency and stability. The generating frequency is turned by a PLL. which is controlled through the detection on phase difference between outputs and currents of the loads and the output amplitude of MOSFET, Q1 are controlled by their products through the multiplier, which results in the control of the amplitude of voltage controlled oscillation. And finally, the proposed and designed ultrasonic generator is composed by the combination of the function in mentioned above. the analysis results of the proposed circuit shows a good agreement between simulations and experiments.

• Journal of the Korean Society for Nondestructive Testing
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• v.31 no.5
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• pp.508-515
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• 2011

Bovine incisor was investigated using active infrared thermography(IRT) to visualize crack on bovine teeth. An artificial crack was carefully created in bovine incisor sample by compression load of universal tensile machine. While applying a sinusoidal heat wave to the cracked bovine incisor through halogen lamp, consecutive digital infrared images was captured from the sample surface at a frequency synchronized with heat excitation. Phase information of thermal image was calculated by four-point correlation method and processed to produce the phase image of bovine incisor. This phase image showed clearly the crack on the incisor, which was hardly detected in traditional passive thermography.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.20 no.8
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• pp.88-95
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• 2006

This paper proposes an analog type Active Power Filter that adapts to the frequency change of a distributed power supply system. The proposed system removes the harmonic currents in the source power by injecting a compensation current that has the same frequency, 180 degree out of phase with the harmonic currents generated by the load. The detection of the harmonics in the source power for creating the compensating current is realized by a PLL(Phase Lock Loop) and a VCGIC(Voltage Controlled Generalized Impedance Converter). The operation of the proposed system is verified by simulation and experiment.

• Asian Pacific Journal of Cancer Prevention
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• v.16 no.6
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• pp.2145-2150
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• 2015

HPV viruses are integral to the development of cervical cancer. The pathogenesis has been extensively studied. To date, numerous HPV tests and products have been developed and successfully utilized in diagnosis, treatment and prevention of cervical cancer. The HPV DNA test, when combined with other routine cervical cancer screening and diagnostic tests namely exfoliative cytology, visual inspection with acetic acid (VIA) and colposcopy has increased the detection rate of cervical cancer. HPV DNA products could also be measured in other body fluids like urine, lymph node tissue, and serum. HPV association could also be quantified by measuring other parameters like HPV mRNA, viral load, viral integration and methylation status. Vaccination against HPV has been found to decrease the incidence of cervical cancer. Further, therapeutic vaccines for cervical cancer against HPV continue to evolve. All these findings pertaining to HPV could possibly decrease the incidence of cervical cancer in the near future. This review aims to give an overview of the HPV tests and products in use and those under trial currently.

• Journal of Power Electronics
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• v.15 no.6
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• pp.1547-1558
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• 2015

A predictive functional control (PFC) scheme for permanent magnet synchronous motor (PMSM) servo systems is proposed in this paper. The PFC-based method is first introduced in the control design of speed loop. Since the accuracy of the PFC model is influenced by external disturbances and speed detection quantization errors of the low distinguishability optical encoder in servo systems, it is noted that the standard PFC method does not achieve satisfactory results in the presence of strong disturbances. This paper adopted the Kalman filter to observe the load torque, the rotor position and the rotor angular velocity under the condition of a limited precision encoder. The observations are then fed back into PFC model to rebuild it when considering the influence of perturbation. Therefore, an improved PFC method, called the PFC+Kalman filter method, is presented, and a high performance PMSM servo system was achieved. The validity of the proposed controller was tested via experiments. Excellent results were obtained with respect to the speed trajectory tracking, stability, and disturbance rejection.

• Proceedings of the KIEE Conference
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• 2005.07a
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• pp.310-312
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• 2005

An out-of-step condition results from the loss of the synchronism of the generators. A disturbance in a power system causes the generator angle to oscillate. When there is a severe disturbance such as a heavy current fault loss of major generation or loss of a large block of load the oscillation can be severe and even increase largely and finally the out-of-step condition may occur During the power swing and out-of-step conditions, the a apparent impedance at a relay location changes, and the power flow also changes as the angle difference is varied. This paper presents a method to analyze the trajectory of complex power during a power swing and out-of-step condition. The trajectory of the complex power is analyzed when a power swings and a fault occurs. Moreover, the complex power is analyzed when the ratios between the voltages at both sides and the line impedances are changed. These methods are verified through simulation using the ATP/EMTP MODELS.

• Structural Engineering and Mechanics
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• v.52 no.1
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• pp.149-172
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• 2014

Four algorithms for damage detection of trusses are presented in this paper. These approaches can detect damage by using both complete and incomplete measurements. The suggested methods are based on the minimization of the difference between the measured and analytical static responses of structures. A non-linear constrained optimization problem is established to estimate the severity and location of damage. To reach the responses, the successive quadratic method is used. Based on the objective function, the stiffness matrix of the truss should be estimated and inverted in the optimization procedure. The differences of the proposed techniques are rooted in the strategy utilized for inverting the stiffness matrix of the damaged structure. Additionally, for separating the probable damaged members, a new formulation is proposed. This scheme is employed prior to the outset of the optimization process. Furthermore, a new tactic is presented to select the appropriate load pattern. To investigate the robustness and efficiency of the authors' method, several numerical tests are performed. Moreover, Monte Carlo simulation is carried out to assess the effect of noisy measurements on the estimated parameters.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.20 no.9
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• pp.883-889
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• 2009

Since the SRRs(Short Range Radar) load on the GVESs(Ground Vehicle Equipment System) are operated within several hundred meters, it is important to suppress the interferences between the SRRs. These interference are reduced using the frequency separation between channels, however this method isn't a perfect solution owing to a difficulty of a realization for the interference suppression. Thus, a pulse-to-pulse coding used to suppress the interference fundamentally is proposed in this paper. The concept, the application method and the test results of the proposed method have been described in this paper.

• Journal of Communications and Networks
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• v.3 no.4
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• pp.365-373
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• 2001

We propose a new channel reservation protocol which can reduce message delay by using a counter for detection of d source conflict in a WDM single-hop network with non-equivalent propagation delay. A source convict occurs when a source node has the right to transmit more than or equal to two messages simultaneously, which are transmitted using different wavelengths. In such a case, the source node has to newly obtain the right to transmit the message. In the proposed protocol, by using a source conflict counter a source node can detect a source conflict before a wave-length assignment is performed. Therefore, the source node can start a procedure to newly obtain the right to transmit the message which cannot be transmitted due to a source conflict. We analyse the throughput performance by taking the effect of a source conflict into account, and show that the approximate analysis and the computer simulated results are close. Also, from computer simulated results, we show that our proposed protocol can reduce mean message delay dramatically without degrading throughput performance as the offered load becomes large.