• Proceedings of the KIEE Conference
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• 1987.11a
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• pp.530-533
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• 1987

In high-frequency switched mode converters, Series Resonant Converter (SRC) is investigated using state-plane method. Phase plane trajectories of the SRC permit a direct closed form solution of the steady state operation and can make problems easy to solve. This paper describes steady state responses and characteristics of the SRC with respect to various circuit factors. The magnitute of steady state response and the average current through load are clearly related to how such the switching frequency differs from the resonant frequency. The results of the steady state analysis can be used to estimate the device and component stress on the power circuit.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.22 no.51
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• pp.1-10
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• 1999

In recent industry society, it is revealed that, as an increase in the use of automated manufacturing and process inspection technology, the data from mass production system exhibits some degrees of autocorrelation. The operation characteristics of traditional control charts developed under the independence assumption are adversely affected by the presence of serial correlation. Therefore, when autocorrelated construction contacted with time-series models explain, the time-series models are the Box-Jenkins forecast models which have been proposed as the best forecasting tool which allows for partitioning of variation into result from the autocorrelation structure and variation due to unusual but assignable causes. In this paper, for the AR(1) process of Box-Jenkins forecast models, when the constant term ξ are zero and different from zero, I want to analyze the sensitivity of (equation omitted), CUSUM and EWMA control chart for forecast residuals.

• Proceedings of the KIEE Conference
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• 1999.07a
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• pp.302-304
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• 1999

Voltage sag and swell are the most severe factors affecting power quality in distribution systems. This paper discusses an approach to ensure a high quality power supply to critical loads appling voltage-sag compensator. The proposed system consists of a PWM voltage source inverter, connected in series with the line through a single-phase transformer. The operation Principle and Power circuit configuration of the proposed voltage sag compensator are introduced. And then the transfer function of compensator is derived from simplified single phase power circuit, and simulated so that the benefits of this proposed compensator is confirmed through the open loop response.

• Proceedings of the KIEE Conference
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• 2000.07b
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• pp.1224-1226
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• 2000

In this paper, load paralleled type FB series resonant inverter of a new novel type is proposed. In the output control method, phase-shift driving signal control method with CVCF introduces. Also by driving signal patterns, the operation principle of the proposed circuit in detail is described and its characteristics are compared on separated ratio(n). According to each the mode in order to the analysis and characteristic evaluation of the circuit state equations are derived and presented using normalized parameter. To verify the theoretical analysis result, experimental results are provided.

• Journal of the Korea Society of Computer and Information
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• v.21 no.9
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• pp.139-147
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• 2016

In recent, android application developments have been done widely that intensify smart phone utilization. In this paper, we propose a curriculum that undergraduate students can improve their mobile programming abilities as well as integrate experiences of application development based on android. And also a series of practices to advance their sense of accomplishment are added by offering an opportunity to carry out a real project to use a variety of sensors embedded in smart phone during the course of study. The project is composed of a series of modules for implementing a trekking App that helpful to people who enjoy spending time in outdoors through their favorite activities such as trekking, cycling, and climbing with their own smart phones. Through practical curriculum operation and project implementation, we show that the proposed curriculum is appropriate to a mobile programming education that combine learning and practice.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.28 no.7
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• pp.62-68
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• 2014

We proposed a series connection-type superconducting fault current limiter(SFCL) using E-I core that can prevent the internal magnetic flux generation of cores during normal operation, and prevent the saturation of cores due to a sudden magnetic flux generation at the initial stage of fault occurrence while limiting the peak current. Through a short-circuit simulation experiment, we analyzed the operating status of the two superconducting elements and limiting characteristics according to the size of the fault current peak before and after the failure. Further, the double peak current limiting characteristics according to the winding directions as well as the current and the voltage of each coil were compared and analyzed.

• Proceedings of the KIEE Conference
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• 2005.10c
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• pp.169-171
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• 2005

In this paper, a novel type of auxiliary switched capacitor assisted edge resonant soft switching PWM series load resonant high frequency inverter with two auxiliary edge resonant lossless inductor snubbers is proposed for small consumer induction heating appliances. The operation principle of this high frequency inverter is described using the switching mode equivalent circuits. The practical effectiveness of the newly proposed soft switching inverter are discussed as compared with the conventional soft switching high frequency inverters based on simulation and experimental results from an application point of view.

• Proceedings of the KIEE Conference
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• 1995.07a
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• pp.368-370
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• 1995

A new three-level push-pull type quantum series resonant rectifier for the power factor correction is proposed. The proposed single phase rectifier enables a zero-current switching operation of all the power devices allowing the circuit to operate at high switching frequencies and high power levels. With the proposed control technique, an unity power factor and greatly reduced line current harmonics can be obtained.

• Journal of Chest Surgery
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• v.27 no.8
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• pp.689-694
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• 1994

A retrospective analysis was performed on 36 patients with primary cysts and tumors of the mediastinum seen at the Department of Thoracic and Cardiovascular Surgery of Maryknoll Hospital from January 1983 to December 1993. There were 21 female and 15 male patients in the study. Ages ranges from 2 years to 72 years, with a mean of 34.7. There were 9 malignant tumors and 27 benign tumors.Thymic neoplasms were the most common. For the whole series, 29 of the patients had tumors in the anterior mediastinum. There appears to be an in6rease in tumors in the anterior compartment. There were 30 symptomatic patients in our series. Of the patients with malignant disease, 89 % were symptomatic. All of benign tumors were completely removed and malignant tumors were treated with chemotherapy and radiotherapy after operation. There were 9[27.3 %] postoperative complications. There was no postoperative mortality. Follow-up was available on 27 patients. There was no recurrence, malignant degeneration, or growth of any tumor. It is hoped that careful evaluation and aggressive treatment of mediastinal tumors will continue to provide improvement in the prognosis for these patients.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.26 no.4
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• pp.101-109
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• 2018

In order to predict the future needs of the aircraft repair parts, each military group develops and applies various techniques to their characteristics. However, the aircraft and the equipped weapon systems are becoming increasingly advanced, and there is a problem in improving the hit rate by applying the existing demand prediction technique due to the change of the aircraft condition according to the long term operation of the aircraft. In this study, we propose a new prediction model based on the conventional time-series analysis technique to improve the prediction accuracy of aircraft repair parts by using machine learning model. And we show the most effective predictive method by demonstrating the change of hit rate based on actual data.