• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.14 no.6
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• pp.12-17
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• 2000

IN induction heating system the high frequency operation allows a rapid response to current fluctuation in the inverter and result in improved welding quality. To work induction heating of nonferrous metals, a welding power supply is need high working frequency and high power. This paper is shown design technique for increasing working frequency in induction heating for welding coppers. A series-parallel resonate inverter consists of H-type bridges, each of whose arms is composed of a combination of two parallel IGBTs. Inverter operating with the fixed frequency is controlled by pulse width modulation (PWM). As switching adapted the Zero-Voltage Switching technique to reduce switching losses the system is high efficiency. The propose inverter has feature which is high efficiency for very wide load variations with a narrow range of duty cycle ratio control and load short circuit capability. Detailed experimental results obtained from a 48[V] output, 500[W] experimental inverter are presented to verify the concept.

• Journal of the Chungcheong Mathematical Society
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• v.33 no.3
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• pp.327-337
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• 2020

This article continues the study of right 𝜋-duo rings, concentrating on the situation of nonzero powers. For this purpose we introduce the concept of strongly right 𝜋-duo and examine the structure of strongly right 𝜋-duo in relation to various ring properties that play important roles in ring theory. It is proved for a strongly right 𝜋-duo ring R that if the upper (lower) nilradical of R is zero then R is reduced. Various kinds of examples are examined in relation to the questions raised in the procedure.

• Journal of the Korean Institute of Telematics and Electronics
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• v.24 no.5
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• pp.841-848
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• 1987

This paper presents a new two-stage edge detection algorithm which can give thin edges and can find edges between low contrast regions. In the first stage, the potential edge points are obtained using the proposed edge operator which is motivated by the concept of the E filter. And in the second stage, the real edge points adre detected by comparing the potential edge values with the lically adaptive threshold values of the corresponding potential edge points and by testing whether the potential edge points are zero-crossing points or not. It is shown quantitatively that the proposed algorithm can find edges effectively in an image with impulse noise, and also the results of applying the proposed algorithm to real images are presented.

• Proceedings of the KIEE Conference
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• 2006.07b
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• pp.982-983
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• 2006

This paper deals with an analysis and design of the state feedback current controller's gain in the three-phase current control systems. First, this paper derives the transfer function of the closed loop current control system and also compares the state feedback current controller with the conventional proportional integral controller. A new pole placement method by using the pole/zero cancellation method is proposed to give a simple and concrete concept with respect to the pole selection. Experimental results on the permanent magnet synchronous motor show that the proposed method is very useful to design the gain of the state feedback current controller.

• Proceedings of the KIPE Conference
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• 2001.12a
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• pp.181-184
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• 2001

In this paper, a novel overmodulation strategy for space-vector PWM(SVPWM) inverters to utilize dc link voltage fully is presented. The proposed strategy uses the concept of SVPWM based on the zero sequence signal(offset voltage) injection principle. So, by modifying the pole voltage simply, the linear control of inverter output voltage over the whole overmodulation range can be achieved easily. The validity of the proposed strategy is confirmed by the experimental results.

• The Transactions of the Korean Institute of Power Electronics
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• v.7 no.2
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• pp.149-157
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• 2002

In this paper, a novel overmodulation strategy for space-vector PWM(SVPWM) inverters to utilize dc link voltage fully Is presented. The proposed strategy uses the concept of SVPWM based on the zero sequence signal(offset voltage) injection principle. So, by modifying the pole voltage simply, the linear control of inverter output voltage over the whole overmodulation range can be achieved easily The proposed strategy is so simple that its practical implementation is easy. The validity of the proposed strategy is confirmed by the experimental results.

• Proceedings of the KIEE Conference
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• 2004.05a
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• pp.138-140
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• 2004

This paper mainly deals with the dynamic walking of a biped robot. At first, in order to walk in various environments, it is desirable to adapt to such ground conditions with a suitable foot motion, and maintain the stability of the robot by a smooth hip motion. A method to plan a walking pattern consisting of a foot trajectory and a hip trajectory is presented. The effectiveness of the proposed method is illustrated by simulation results. Secondly, the paper brings forward a balance control technique based on off-line walking pattern with real-time modification. At last, the concept of Zero Moment Point (ZMP) is used to evaluate dynamic stability.

• International Journal of Computer Science & Network Security
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• v.24 no.4
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• pp.155-162
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• 2024

Anonymity online has been an ever so fundamental topic among journalists, experts, cybersecurity professionals, corporate whistleblowers. Highest degree of anonymity online can be obtained by mimicking a normal everyday user of the internet. Without raising any flags of suspicion and perfectly merging with the masses of public users. Online Security is a very diverse topic, with new exploits, malwares, ransomwares, zero-day attacks, breaches occurring every day, staying updated with the latest security measures against them is quite expensive and resource intensive. Network security through anonymity focuses on being unidentifiable by disguising or blending into the public to become invisible to the targeted attacks. By following strict digital discipline, we can avoid all the malicious attacks as a whole. In this paper we have demonstrated a proof of concept and feasibility of securing yourself on a network by being anonymous.

• Korean Institute of Interior Design Journal
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• v.13 no.3
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• pp.35-42
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• 2004

This study dealt with approaches in architecture and music in the contemporary situation characterized by accidence and uncertainty through Pierre Boulez and Rem Koolhaas' works. First of all, we examined basic positions with starting from zero degree breaking from fixed ideas and with relative neutrality. Then, from a methodological aspect, we inquired into 1) anti-hierarchical objective approach, 2) accidental approach to form. 3) diagram of structure and event, and 4) the use of selective routes. Lastly, from a receptive aspect, we dealt with the space of pluralistic perspective and works in progress. The two persons used chaosmos approach that enables adjustment and control through structure defining the relationship with accidence or chaos. With the approach, they created works in progress or open works that have a pluralistic viewpoint working in the field of specific relation and the concept of endless regeneration.

• Proceedings of the KIPE Conference
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• 1998.10a
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• pp.56-61
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• 1998

A soft-switching three-level chopper-inverter system was built for high-power applications like Power Conditioning System (PCS) for Superconductive Magnetic Energy Storage (SMES). The system can handle 1800-VDC, 200-A peak, and 250-kW output power. The system was designed to operate with 20-KHz PWM operation with the aid of state-of-the-art zero-current transition type soft-switching. The system is based on the Power Electronics Building Block (PEBB) concept.