• Journal of Electrical Engineering and Technology
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• v.12 no.6
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• pp.2289-2297
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• 2017

Applying a periodic load torque to an AC motor generates a ripple, which is synchronized to the frequency of the periodic load torque, at the speed of the motor. Consequently, numerous studies have focused on reducing the speed ripple caused by the load torque. However, it is difficult to reduce the speed ripple when there is a time delay in acquiring speed information, such as that from a sensorless control. Therefore, we propose a speed control method for reducing speed ripples caused by a periodic load torque when there is a time delay in acquiring the speed information. The proposed method is verified by conducting simulations using the Simulink program from MATLAB, and by applying the method to an actual motor in which speed ripples occur due to a periodic load torque that is synchronized with the speed of the motor.

• Proceedings of the KIEE Conference
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• 2005.07b
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• pp.927-929
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• 2005

In this paper, through the theoretical study on reducing method and analysis of stray load loss of induction motor, we suggest the improved design considering the slot combination, skew, air gap and manufacturing method. For verifying the suggested design, the test was performed by IEEE 112. As a result, the reducing technology on the stray load loss was established.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.64 no.6
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• pp.852-856
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• 2015

Demand side management (DSM) program has been frequently used for reducing the system peak load because it gives utilities and independent system operator (ISO) a convenient way to control and change amount of electric usage of end-use customer. Planning and operating methods are needed to efficiently manage a DSM program. This paper presents a planning method for DSM program. A planning method for DSM program should include an electric load forecasting, because this is the most important factor in determining how much to reduce electric load. In this paper, load forecasting with the temperature stochastic modeling and the sensitivity to temperature of the electric load is used for improving load forecasting accuracy. The proposed planning method can also estimate the required day, hour and total capacity of DSM program using Monte-Carlo simulation. The results of case studies are presented to show the effectiveness of the proposed planning method.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.9
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• pp.1700-1705
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• 2009

In general, short term load forecasting is based on the periodical load pattern during a day or a week. Therefore, the conventional methods do not expose stable performance to every day during a year. Especially for anomalous weather conditions such as typhoons, the methods have a tendency to show the conspicuous accuracy deterioration. Furthermore, the tendency raises the reliability and stability problems of the conventional load forecast. In this study, a new load forecasting method is proposed in order to increase the accuracy of the forecast result in case of anomalous weather conditions such as typhoons. For irregular weather conditions, the sensitivity between temperature and daily load is used to improve the accuracy of the load forecast. The proposed method was tested with the actual load profiles during 14 years, which shows that the suggested scheme considerably improves the accuracy of the load forecast results.

• Computers and Concrete
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• v.11 no.1
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• pp.63-73
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• 2013

In this study, the effect of reducing cement by proportional addition of waste powder rubber on the performance of concrete under impact three-point bending loading were investigated experimentally and numerically. Concrete specimens were prepared by adding 5%, 10% and 20 % of rubber powder as filler to the mix and decreasing the same percentage of cement. For each case, three beams of $50mm{\times}100mm{\times}500mm$ were loaded to failure in a drop-weight impact machine by subjecting them to 20 N weight from 300mm height, while another three similar beams were tested under static load. The bending load-displacement behavior was analyzed for the plain and rubberized specimens, under static and impact loads. A three dimensional finite-element method simulation was also performed by using LUSAS V.14 in order to study the impact load-displacement behavior, and the predictions were validated with the experimental results. It was observed that, despite decreasing the cement content, the proportional addition of powder rubber until 10% could yield enhancements in impact tup, inertial load and bending load.

• Journal of the Korean Institute of Telematics and Electronics
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• v.24 no.4
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• pp.684-695
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• 1987

In this paper, an improved matching method using subtemplate of moving region and 3-step search algorithm is proposed. It reduces heavy computational load of the conventional method and also can continuously track the target even with occlusion. The proposed method is applied to an automatic target tracker using high speed 16bit microprocessor in order to track one moving target in real time. Experimental results show that the proposed method has better performance over the conventional method in spite of greately reducing the computational load, even in case with complex background and/or with occlusion.

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 1987.04a
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• pp.52-55
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• 1987

In tihis paper an improved matching method using subtemplate of moving region and 3-step search algorithm is proposed It reduces heavy computational load of the conventional method. The proposed method is applied to an automatic target tracker using high speed 16 bit microprocessor in order to track one moving target in real time. Expericmental results show that the proposed method has better performance over the conventional methodin spite of greately reducing the computational load, even in came complex background.

• Proceedings of the IEEK Conference
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• 2006.06a
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• pp.301-302
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• 2006

Load effect which occurs due to the electrode structure for PDP(plasma display panel) can seriously reduce the image quality of PDP. In this paper, we propose the method of reducing load effect in presentation images, which have the possibility of load effect, by using LUT(look-up table). The proposed method enhances the image quality of PDP by correcting load effect region of the still image.

• Journal of Power Electronics
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• v.18 no.1
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• pp.300-308
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• 2018

An online estimation method for wireless power transfer (WPT) systems is presented without using any measurement of the secondary side or the load. This parameter estimation method can be applied with a controlling strategy that removes both the receiving terminal controller and the wireless communication. This improves the reliability of the system while reducing its costs and size. In a wireless power transfer system with an LCCL impedance matching circuit under a rectifier load, the actual load value, voltage/current and mutual inductance can be reflected through reflected impedance measuring at the primary side. The proposed method can calculate the phase angle tangent value of the secondary loop circuit impedance via the reflected impedance, which is unrelated to the mutual inductance. Then the load value can be determined based on the relationships between the load value and the secondary loop impedance. After that, the mutual inductance and transfer efficiency can be computed. According to the primary side voltage and current, the load voltage and current can also be detected in real-time. Experiments have verified that high estimation accuracy can be achieved with the proposed method. A single-controller based on the proposed parameter estimation method is established to achieve constant current control over a WPT system.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.15 no.1
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• pp.9-17
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• 2019

Reducing global warming potential has become important, and as one of those methods for reducing it, economic evaluation by applying ice thermal storage air conditioning system was performed. The floor area and height of the subject building was assumed $5,000m^2$ and 20 m. Absorption chillerheater system and air source heat pump system was used for comparing to the subject system, and payback period method was used to perform economic evaluation. Although the running cost of ice thermal storage system is reduced compared to two systems, the ratio is not significant compared to the increase of initial construction expenses, and payback period was calculated to be about 7.7 and 79.3 years. However, the heat storage system should be approached from the viewpoint of long term rather than the economic standard in the present standard.