• The Transactions of the Korean Institute of Power Electronics
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• v.15 no.2
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• pp.119-126
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• 2010

An integrated magnetic (IM) transformer is proposed for a phase shifted full bridge (PSFB) converter with zero voltage switching (ZVS). In a proposed IM transformer, the transformer is located on the center leg of E-core and the output inductor is wound on two outer legs with air gap. The proposed IM transformer is analyzed by using the magnetic capacitor model. For reducing the core size, EE core is redesigned. The proposed IM transformer is experimentally verified on a 1.2 kW prototype converter. The converter efficiency with the proposed IM transformer is about 93 % at full load and its volume size can be reduced. It can be expected that the power density can be largely increased with the proposed IM transformer.

• The Transactions of the Korean Institute of Power Electronics
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• v.22 no.2
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• pp.118-125
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• 2017

In this paper, we propose a smart transformer for a smart transformer miniature model, which can replace a 60 [Hz] single-phase transformer installed in an electric vehicle. The proposed smart transformer is lighter than a conventional transformer, can control instantaneous voltage, and can be expected to improve power quality through harmonic compensation. The proposed intelligent transformer consists of an incoming part, an AC/DC converter, and a dual active bridge. Only the incoming part and the AC/DC converter are described in this paper. The proposed intelligent transformer has 75 kVA 3.3 kV input and 750 V DC output, which are verified by simulation and experiment.

• Journal of Broadcast Engineering
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• v.27 no.7
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• pp.1011-1020
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• 2022

Recent high-performance panoptic segmentation models are based on transformer architectures. However, transformer-based panoptic segmentation methods are basically slower than convolution-based methods, since the attention mechanism in the transformer requires quadratic complexity w.r.t. image resolution. Also, sine and cosine computation for positional embedding in the transformer also yields a bottleneck for computation time. To address these problems, we adopt three modules to speed up the inference runtime of the transformer-based panoptic segmentation. First, we perform channel-level reduction using depth-wise separable convolution for inputs of the transformer decoder. Second, we replace sine and cosine-based positional encoding with convolution operations, called conv-embedding. We also apply a separable self-attention to the transformer encoder to lower quadratic complexity to linear one for numbers of image pixels. As result, the proposed model achieves 44% faster frame per second than baseline on ADE20K panoptic validation dataset, when we use all three modules.

• Journal of international Conference on Electrical Machines and Systems
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• v.3 no.1
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• pp.78-82
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• 2014

Power Transformers with more than one secondary winding are not uncommon in industrial applications. But new classes of applications where very large number of independent secondaries are used are becoming popular in controlled converters for medium and high voltage applications. Cascade H-bridge medium voltage drives and Pulse Step Modulation (PSM) based high voltage power supplies are such applications. Regulated high voltage power supplies (Fig. 1) with 35-100 kV, 5-10 MW output range with very fast dynamics (${\mu}S$ order) uses such transformers. Such power supplies are widely used in fusion research. Here series connection of isolated voltage sources with conventional switching semiconductor devices is achieved by large number of separate transformers or by single unit of multi-secondary transformer. Naturally, a transformer having numbers of secondary windings (~40) on single core is the preferred solution due to space and cost considerations. For design and simulation analysis of such a power supply, the model of a multi-secondary transformer poses special problem to any circuit analysis software as many simulation softwares provide transformer models with limited number (3-6) of secondary windings. Multi-Secondary transformer models with 3 different schemes are available. A comparison of test results from a practical Multi-secondary transformer with a simulation model using magnetic component is found to describe the behavior closer to observed test results. Earlier models assumed magnetising inductance in a linear loss less core model although in actual it is saturable core made-up of CRGO steel laminations. This article discusses a more detailed representation of flux coupled magnetic model with saturable core properties to simulate actual transformers very close to its observed parameters in test and actual usage.

• Proceedings of the KIEE Conference
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• 1996.07b
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• pp.844-846
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• 1996

This paper deals with a simulation method of faults in a power transformer. Using the [R],[L] matrix supplied by the auxiliary routine of EMTP called BCTRAN, the turn to ground fault and turn to turn fault are simulated and the inrush condition is simulated using saturable transformer model. Data from simulations can be used to identify the response of the digital protection algorithms for transformer.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.649-655
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• 2011

In this paper, the content to carry out the modal testing and to analyze the data as the target of the main transformer installed on KTX is mentioned. The main transformer for KTX is a structure which is over 10 Ton. For the possibility to occur a stress concentration phenomenon exists, the dynamic durability of the system is experimentally needed to understand. To do this, we obtained the vibration data using an accelerometer, an impact hammer, a measuring instrument and gained the frequency response function of the main transformer based on the acquisition data. In this content, when the theoretical model for structural analysis should be established, we think it will be used for the property verification of analytical model. Also, we expect that the measured and analysed data will offer basic research material to maintain the system and diagnose the condition by monitoring the natural frequency of the main transformer for KTX periodically.

• Proceedings of the KIPE Conference
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• 2017.11a
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• pp.27-28
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• 2017

In this paper, design method for a high frequency transformer with high insulation is presented. The insulation performance of the high frequency transformer is determined by the distance between primary and secondary windings, and the characteristics of dielectric material. For the voltage strength safty, a high frequency transformer model is designed. By using computer simulation, the transformer model is evaluated.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.54 no.1
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• pp.15-19
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• 2005

This paper analyzed the power loss characteristics according to winding thickness and winding method of high frequency transformer. Power loss was analyzed by PExprt using FEM tool. The ferrite core model for analysis be used the EE10 type of TDK cop.. Transformer model objected flyback transformer type applied to flyback converter/inverter. Therefore, analysis results of loss were obtained from inner parameters of DC, AC resistance, leakage inductance, copper loss, core loss, and temperature etc.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.1
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• pp.113-118
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• 2010

In This Paper, at the PSPICE model is presented by Piezoelectric Transformer and CCFL and equivalent circuit of fluorescent light. Highly effective fluorescent light release for next generation is developed for 35W supremacy model three wave length T5 fluorescent lamps. Lighting a candle experiment of T5 fluorescent lamps is carried out by employing Piezoelectric Transformer power-factor improvement circuit and inverter. PLL method is used for supplying a correct frequency of Piezoelectric Transformer operating.

• Proceedings of the KIEE Conference
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• 1997.07a
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• pp.256-259
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• 1997

This paper describes on the leakage inductance calculations of superconducting (s/c) tranformer. When s/c transformer quenches, the magnetic energy stored in the leakage inductance dissipates in the form of Joule heating. So, it is highly desired to estimate the leakage inductances of a s/c transformer as it is designed. In this paper, we calculated the leakage inductance of sic transformer, using zeroth and first order model, and the calculated results were compared with the measured ones. It shows that 1st order model is enough to estimate the leakage inductacne of s/c transformer.