• Journal of Power Electronics
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• v.12 no.6
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• pp.851-858
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• 2012

This paper presents resonant inverter tuning for current source parallel resonant induction heating systems based on a new self oscillating switching technique. The phase error is suppressed in a wide range of operating frequencies in comparison with Phase Locked Loop (PLL) techniques. The proposed switching method has the capability of tuning under fast changes in the resonant frequency. According to this switching method, a multi-frequency induction heating (IH) system is proposed by using a single inverter. In comparison with multi-level inverter based IH systems, the advantages of this technique are its simple structure, better transients and wide range of operating frequencies. A laboratory prototype was built with an operating frequency of 35 kHz to 55 kHz and 300 W of output power. The performance of the IH system shows the validity of the new switching technique.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.919-920
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• 2007

Currently national High Voltage Gas Insulated Switchgear (GIS) operating mechanism is made up of spring operating mechanism or hydraulic operating mechanism. On the contrary, advanced technology trend in foreign countries replace current mechanical mechanism with electrical motor-drive mechanism that leads to participate GIS bid and increase sales with the point of simplification of driving system and IT application. Therefor it is essential to develop high voltage GIS using the motor-drive system to develop national heavy electric machine industries and catch up the technology to the advanced level. This paper therefore presents design and analysis of permanent synchronous motor for high voltage GIS, verifies the performance by the experimental test.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.33-35
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• 2007

This paper studies on operating limit curve of low voltage electric machinery with respect to source voltage variation or sag. Also, it discusses electric machine and compensation equipment design methodology based on voltage quality effect assessment technology. Voltage quality standards, such as SEMI47, CBEMA, ITIC curve are regarded to examine the relation between time constants of load and sagging time of sag generator, the load(low voltage electric machinery) study. Voltage sag characteristics of loads, time constant and sag relation voltage-time operating limits are tested and verified.

• Journal of the Semiconductor & Display Technology
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• v.16 no.3
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• pp.25-30
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• 2017

Arago's disk system consists of a speed controller of the DC motor (inner loop controller) and a position controller of the magnetic bar angle (main controller), which are implemented by the design of the PI and PID controller, respectively. First, we analyzed the nonlinear characteristics of the Arago disk system and found the operating point range of three locations as a result. In this paper, a gain scheduler method was applied to guarantee a constant control performance in the range of $0{\sim}130^{\circ}C$, and a structure to change the controller according to the control reference value based on the previously obtained operating points was experimentally implemented. The Distributed Control Systems (DCS) configuration using the Controller Area Network (CAN) was used to verify the proposed method by improving the operational efficiency of the entire experimental system. So, simplicity of the circuit and easy diagnosis were achieved through a single CAN bus communication.

• Journal of Ceramic Processing Research
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• v.19 no.6
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• pp.514-518
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• 2018

The direct carbon fuel cell (DCFC) has attracted researcher's attention recently, due to its high conversion efficiency and its abundant fuel, carbon. A DCFC mathematical model has developed in two-dimensional, lab-scale, and considers Boudouard reaction and carbon monoxide (CO) oxidation. The model simulates the CO production by Boudouard reaction and additional electron production by CO oxidation. The Boudouard equilibrium strongly depends on operating temperature and affects the amount of produced CO and consequentially affects the overall fuel cell performance. Two different operating temperatures (973 K, 1023 K) has been calculated to discover the CO production by Boudouard reaction and overall fuel cell performance. Moreover, anode thickness of the cell has been considered to find out the influence of the Boudouard reaction zone in fuel cell performance. It was found that in high temperature operating DCFC modeling, the Boudouard reaction cannot be neglected and has a vital role in the overall fuel cell performance.

• The Journal of the Convergence on Culture Technology
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• v.6 no.2
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• pp.357-367
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• 2020

This study is a qualitative study conducted to understand and explain the operating room practice experience of nursing college students. Participants in this study were 67 nursing college students in 3rd and 4th grade at a university in C-gun, Gyeongsangbuk-do who participated in the practice of operating rooms. The data collection period was from January 14, 2019 to January 13, 2020, and the data collection was carried out through an open self-report-style reflection log, and the collected data was analyzed using the traditional content analysis method of Krippendorff [21]. Analysis of the operating room practice experience of nursing college students resulted in 27 sub-themes, 12 themes and 5 categories. The five categories are "Being seized with complicated feelings," "Being faced with dissection body," "Learning the characteristics of the operating room, " "Being confronted with the limits of clinical practice" and "Self-reflection." The results of this study provided an understanding of the operating room practice experience of nursing students and are expected to be used as basic data to improve the quality of practice of nursing students.

• Journal of the Korea Society of Computer and Information
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• v.26 no.7
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• pp.91-102
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• 2021

The effectiveness of informatization can vary depending on the level of operation of the information system as well as investment and installation. This study investigates and analyzes the information system operating environment and quality level of small and medium-sized manufacturing companies in Korea, and investigates how it affects the performance indicators of companies. The influence of the environmental factors operating the information system on the productivity performance and financial performance through the quality level of the information system was analyzed through the structural model. As a result of the analysis, it can be said that the higher the level of information system operating environment factors, the higher the quality level, the higher the quality level, the higher the productivity performance, and the higher the productivity performance, the higher the financial performance. It is judged that the effect of informatization depends on the operating environment and quality level after the installation of the information system.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.43 no.6
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• pp.865-871
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• 2023

Domestic urban railway are operated by urban railway operating public enterprises, which are owned by the 6 major metropolitan local governments and private operating companies, which are established under the Private Investment Act. Among urban railway operating companies, several public enterprises that operate urban railways with many experience, performance, human resources, and public nature are making efforts to promote overseas business. Therefore, this study examines the outlook for railway and urban railway overseas business, and provides implications for the overseas business approach of domestic urban railway operating public enterprises through data research and comparative analysis on the overseas business approaches and overseas business characteristics of domestic and foreign urban railway operating public enterprises. The results were derived and suggestions for the direction of overseas business were presented. I expect that suggestions will serve as a reference for domestic urban railway operators to promote overseas projects with preparation, implementation plan and direction.

• IE interfaces
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• v.23 no.3
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• pp.221-228
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• 2010

With the development of science and technology, modern submarines are equipped with high technology devices and multi-functioned precise armaments, consequently, acquisition cost as well as maintenance cost of the submarines are getting higher and higher. However, tight defense budget forces navy to significantly reduce military operating and maintenance costs. In this study, the maintenance and operating costs of submarine Jangbogo-II are estimated through M&S (Modeling and simulation) methodologies in order to reasonably and consistently work out the requirement verification system of Jangbogo-II. The maintenance and operating costs of Jangbogo-II along the next 25 years are estimated as 312.65 billion won via engineering analysis methods while 312.69 billion won from PRICE Model, which shows only 0.04 billion won differences as a whole. This study is expected to be able to provide meaningful decision making data for not only short and/or mid term operating planning but military budgeting.

• Journal of Advanced Marine Engineering and Technology
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• v.32 no.6
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• pp.955-963
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• 2008

In this paper, we propose an improved practical encryption and fault-tolerance decryption method using a non-negative value key and random function obtained with a white noise by using iterative phase wrapping method. A phase wrapping operating key, which is generated by the product of arbitrary random phase images and an original phase image. is zero-padded and Fourier transformed. Fourier operating key is then obtained by taking the real-valued data from this Fourier transformed image. Also the random phase wrapping operating key is made from these arbitrary random phase images and the same iterative phase wrapping method. We obtain a Fourier random operating key through the same method in the encryption process. For practical transmission of encryption and decryption keys via Internet, these keys should be intensity maps with non-negative values. The encryption key and the decryption key to meet this requirement are generated by the addition of the absolute of its minimum value to each of Fourier keys, respectively. The decryption based on 2-f setup with spatial filter is simply performed by the inverse Fourier transform of the multiplication between the encryption key and the decryption key and also can be used as a current spatial light modulator technology by phase encoding of the non-negative values. Computer simulations show the validity of the encryption method and the robust decryption system in the proposed technique.