• Journal of the Semiconductor & Display Technology
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• v.23 no.1
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• pp.19-24
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• 2024

It is not an exaggeration to say that a single fire causes a lot of damage, so fires are one of the disaster situations that must be alerted as soon as possible. Various technologies have been utilized so far because preventing and detecting fires can never be completely accomplished with individual human efforts. Recently, deep learning technology has been developed, and fire detection systems using object detection neural networks are being actively studied. In this paper, we propose a new fire detection system that improves the previously studied fire detection system. We train the YOLOv8 model using refined datasets through improved labeling methods, derive results, and demonstrate the superiority of the proposed system by comparing it with the results of previous studies.

• Proceedings of the KIEE Conference
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• 1997.07f
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• pp.2010-2012
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• 1997

A cascade multilevel voltage source inverter is introduced to apply the advanced static var compensator(ASVC) for large scale power application. This cascade M-level inverter consists of (M-1)/2 single-phase full bridges. This inverter is suitable to the flexible ac transmission systems(FACTS) including SVC, series compensation and phase shifting. It can solve the problems of conventional transformer -based multipulse inverters and multilevel diode-clamped inverters. From the simulation results, the validity of ASVC with cascade multilevel inverter is shown for high power application.

• Journal of Power Electronics
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• v.4 no.3
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• pp.152-160
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• 2004

This paper presents analysis, modeling, and design of a low-harmonic, isolated, active-clamped SEPIC for future avionics applications. Simpler converter dynamics, high switching frequency, zero voltage-Transition-PWM switching, and a single-layer transformer construction result. This paper describes complete design of a digital controller for a high-frequency switching power supply. Guidelines for the minimum required resolution of the analog-to-digital converter, the pulse-width modulator, and the fixed-point computational unit is derived. A design example based on a SEPIC converter operating at the high switching frequency is presented. The controller design is based on direct digital design approach and standard root-locus techniques.

• Proceedings of the KIEE Conference
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• 1997.07a
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• pp.124-126
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• 1997

A number of electromagnetic devices periodically driven by solid-state switches have been analyzed with time-stepping finite element method, which requires much time to reach a steady state. The sensitivity analysis which have been used for the shape design is employed for an efficient calculation of linear magnetodynamics with nonsinusoidal driving sources. The high-order frequency sensitivity from the harmonic finite element formulation is used along with Fourier transform and Taylor series expansion. The algorithm is validated through a numerical example of a single-phase transformer driven by a trapezoidal voltage source.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.913-914
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• 2007

Power transformer shall be designed and constructed to withstand the mechanical and thermal stresses produced by external short circuits which include three-phase, single line to ground, double line-to-ground, and line-to-line faults on any one set terminals at a time. This paper presents the method of short-circuit test and means of evaluation during and after each test to judge the results of short-circuit tests.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.11a
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• pp.73-76
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• 1999

In this thesis, we fabricate a zero-magnetostrictive amorphous ribbon measure the impeadance effect, and then Investigate possibility as a sensor material. $Co_{72.5}$F $e_{0.5}$M $o_{2}$ $B_{15}$ S $i_{5}$ is used as composition of specimen alloy. We first melt the specimen in high frequency induction furnace and then rapidly quench it by using single roll technique. As the result, we obtain a ribbon where thickness is 12${\mu}{\textrm}{m}$, width is 1mm and length is 93mm. Consequently, it is proved through this study that zero-magnetostrictive amorphous ribbon can be used as an excellent magnetic sensor material.rial.l.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.52 no.11
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• pp.647-654
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• 2003

As electrical power system has become complicated and enlarged to cope with the increasing electric demand, it has to be expected that higher speed, higher reliability, higher function and higher arithmetic ability in protective relay should be realized. Therefore, in this papers, by hardware design and implementation used DMA controller that transfer blocks of data to any location in the memory map without interfering with CPU operation, CPU utilization is increased effectively, as a result it made possible to implement multi-function digital protective relay which has high trust and high function of protection as well as control and metering for power transformers using single processor(DSP).

• Journal of international Conference on Electrical Machines and Systems
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• v.2 no.2
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• pp.197-201
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• 2013

Cascaded H-bridge multilevel inverter requires independent DC voltage sources to produce multi output voltage levels. When it needs to generate more levels in the output voltage wave, the number of independent DC voltage sources usually limits its extension. To solve this problem, we propose a cascaded H-bridge multilevel inverter employing a front-end flyback converter for unifying input DC voltage sources. After theoretical analysis of the proposed circuit, we verify the validity of the proposed inverter using computer-aided simulations and experiments.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.10
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• pp.1916-1922
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• 2009

Introducing distributed generators(DGs) to utility distribution system can cause malfunction of relay on the grid when ground faults or severe load unbalances are occurred on the system. Because DGs interconnected to the grid can contribute fault currents and make bidirectional power flows on the system, fault currents from DGs can cause an interference of relay operation. A directional over current relay(DOCR) can determine the direction of power flow whether a fault occurs at the source side or load side through detecting the phases of voltage and current simultaneously. However, it is identified in this paper that the contributed fault current(Ifdg) from the ground source when was occurred to contribute single-line-to-ground(SLG) fault current, has various phases according to the distances from the ground source. It means that the directionality of Ifdg may not be determined by simply detecting the phases of voltage and current in some fault conditions. The magnitude of Ifdg can be estimated approximately as high as 3 times of a phase current and its maximum is up to 2,000 A depending on the capacity of generation facilities. In order to prevent malfunction of relay and damage of DG facilities from the contribution of ground fault currents, Ifdg should be limited within a proper range. Installation of neutral ground reactor (NGR) at a primary neutral of interconnection transformer was suggested in the paper. Capacity of the proposed NGR can be adjusted easily by controlling taps of the NGR. An algorithm for unidirectional relay was also proposed to prevent the malfunction of relay due to the fault current, Ifdg. By the algorithm, it is possible to determine the directionality of fault from measuring only the magnitude of fault current. It also implies that the directionality of fault can be detected by unidirectional relay without replacement of relay with the bidirectional relay.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.23 no.5
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• pp.88-95
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• 2009

This paper is the research on the development of power conversion system for the fuel cell. In composing the DC/DC converters which have high boost voltage ratio, unlike the conventional method a new multi DC/DC converter system is proposed that the diode and the condenser and the reactor can be reduced by connecting the secondary side output of the transformer. In this system the rectifier part and the filter part of the secondary side in the power transformer that is connecting in series are composed into a single module, which is the strong advantage and the number of level can be easily increased. A new variable shift phase switching method is also suggested that it makes possible to reduce the output voltage ripples in the proposed system. All the factors mentioned above have been verified through simulations and experiments, and the proposed converter is considered very useful in the demanded load which requires a wide of the output.