• Journal of IKEEE
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• v.22 no.1
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• pp.216-222
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• 2018

Long-range wireless power transmission technology goes beyond mere cell phones and small appliances, and is the core technology of 4'th industrial revolution such as robot, electric car, and IoT sensor network. In this paper, we will explore the evolution of long-range wireless power transmission technologies that have already become commercially available, with rapid advances in technology, beyond the traditional short-range technology that has become technologically common. Through this, it is intended to check the domestic research level and progress by identifying core technologies and technical challenge.

• Proceedings of the KIEE Conference
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• 2004.11c
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• pp.741-743
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• 2004

In this paper, we describe a Control Element Drive Mechanism(CEDM) operation test using a Power Controller. By testing, we can catch the mechanical and electrical characteristics of CEDM and obtain the information about the improvement of CEDM and the design of CEDM power cabinet. The power controller for CEDM introduced in this paper can input firing angles directly into gate drive circuits of thyristors so that this method can be used to derive the maximum and minimum values of firing angles within available limits for a 3-phase half-wave rectifier. Angle inputs help us understand each coil's response characteristics. Since this power controller generates a serial sequence for CEDM insertion and withdrawal operations, we may judge whether CEDM works correctly as expected or not in each phase of a step movement.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.55 no.8
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• pp.399-403
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• 2006

An accurate constant output voltage provided by the analog memory cell may be used by the low power oscillator to generate an accurate low frequency output signal. This accurate low frequency output signal may be used to maintain long-term timing accuracy in host devices during sleep modes of operation when an external crystal is not available to provide a clock signal. Further, incorporation of the analog memory cell in the low power oscillator is fully implementable in a 0.35um Samsung standard CMOS process. Therefore, the analog memory cell incorporated into the low power oscillator avoids the previous problems in a oscillator by providing a temperature-stable, low power consumption, size-efficient method for generating an accurate reference clock signal that can be used to support long sleep mode operation.

• Communications for Statistical Applications and Methods
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• v.15 no.1
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• pp.13-26
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• 2008

Inference on the present data will be more reliable when the data arising from previous similar studies are available. The data arising from previous studies are referred as historical data. The power prior is defined by the likelihood function based on the historical data to the power $a_0$, where $0\;{\le}\;a_0\;{\le}\;1$. The power prior is a useful informative prior for Bayesian inference such as model selection and model comparison. We utilize the historical data to perform multiple comparison in the one-way ANOVA model. We demonstrate our results with some simulated datasets under a simple order restriction between the treatments.

• Proceedings of the KIEE Conference
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• 2005.07a
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• pp.822-824
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• 2005

This paper presents a scheme to solve the congestion problem using phase-shifting transformer(PST) in power systems. Available transfer capability(ATC) is an important indicator of the usable amount of transmission capacity accessible by several parties for commercial trading in power transaction activities. This paper deals with an application of optimization technique for ATC calculation. Sequential quadratic programming(SQP) is used to maximize power flow of tie line subject to security constraints such as voltage magnitude and real power flow. The proposed method is applied to 10 machines 39 buses model systems to show its effectiveness.

• International Journal of Ocean System Engineering
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• v.3 no.4
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• pp.164-168
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• 2013

Tidal-current power is now recognized as a clean power resource. The turbine blade is the fundamental component of a tidal current power turbine. The kinetic energy available within a tidal current can be converted into rotational power by turbine blades. While in service, turbine blades are generally subjected to cyclic fatigue loading due to their rotation and the rotor-tower interaction. Predicting the fatigue life under a hydrodynamic fatigue load is very important to prevent blade failure while in service. To predict the fatigue life, hydrodynamic load data should be acquired. In this study, the vibration characteristics were analyzed based on three-dimensional unsteady simulations to obtain the cyclic fatigue load. Our results can be applied to the fatigue design of horizontal-axis tidal turbines.

• Proceedings of the KIEE Conference
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• 1999.07c
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• pp.1262-1266
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• 1999

More precise operation and control is required to ensure the stability and security of modern large power systems that is a complicated and widely dispersed structure. To ensure the precise operation and control of modern power system, most of all, precise monitoring and measurement of the various state values of power system is required. This paper discusses phasor measurement unit using synchronization signals from the GPS satellite system- Synchronized Phasor Measurement Unit. Considering the power system operation state, the transmitting data format over modems is defined. To provide all available information, PMU process the measurements to generate three phase symmetrical component. This paper proposes the transmitted data format and implements the PMU model using EMTP/Models. The validity of proposed model is confirmed through several contingency on the simple power system.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.51 no.2
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• pp.55-59
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• 2002

Parallel processing is able to be used effectively on computationally intense power system problems. But this technology is not still available is not only parallel computer but also parallel processing scheme. Testing these algorithms to ensure accuracy, and evaluation of their performance is also an issue. Although a significant amount of parallel algorithms of power system problem have been developed in last decade, actual testing on parallel computer architectures lies in the beginning stages because no clear cut paths. This paper presents Jacobian modeling method to supply the base being able to treat power flow by newton's method by the computer. This method is to assign and to compute teared blocks of sparse matrix at each parallel processors. The testing to insure accuracy of developed method have been done on serial computer by trying to simulate a parallel environment.

• Journal of Institute of Control, Robotics and Systems
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• v.13 no.1
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• pp.1-5
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• 2007

Many nonlinear controllers for the power system are based on nonlinear models involving the power angle as an element of the state, and therefore the reference value for the power angle is needed. As this reference value is not generally available, it is difficult to apply such nonlinear control methods in practice. To deal with this problem, we present an input-output feedback linearizing control scheme by selecting the output as a combination of the squared voltage and the relative frequency. It is shown that the internal dynamics are locally stable with controllable damping, and that the frequency remains bounded for all time. Simulations illustrate the effectiveness of the proposed method.

• Journal of Electrical Engineering and Technology
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• v.8 no.3
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• pp.393-401
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• 2013

This paper deals with the operation strategy of the Cheju AC network included MIHVDC system (Multi-Infeed HVDC system). In case that where several HVDC systems are located in the vicinity of each other, there are interactions between the different HVDC systems in such network configurations. The interactions which could be generated in multi-infeed HVDC are voltage stability, power stability and inertia stability, to analyze such systems in a systematic way to ensure that there are no risks of adverse interactions is very important. The developed method until now to analyze MIHVDC interaction is extended from MAP(Maximum Available Power) method for analyzing the power stability of the single-infeed HVDC system, this method is to solve the eigenstructure using the identified factors influencing the interactions. Finally, the algorithms which are introduced in this paper, to determine the operation strategy are applied to Cheju island network which is supplied by two HVDCs.