• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.16 no.6
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• pp.22-29
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• 2002

The conventional neon transformer systems are very bulky and heavy because it consist of leakage type transformers made of silicon steel plates. In addition, it has problems in noise by a neon transformer and in possibilities of fire and electrical shock when neon tubes are destroyed. A protection circuit is designed for all types of neon transformer loaded with one or more neon tubes. Whenever the neon tube fails to be started up, comes to the life end, encounters faults with open-circuits at the output terminals of the neon transformer, the protection circuit will be initiated to avoid more critical hazards. The input of the transformer is automatically cut off when the abnormal condition occurs, preventing waste of no-load power. To improve such problems, in this paper, a new type of neon power supply systems for neon tube is designed and implemented using inverter type circuits and a newly designed lightweight transformer. In the developed neon transformer system, a 60［Hz］power input is converted to 20［KHz］high frequency using half-wave inverters, thereby the transformer reduces its size by 1/5 in volume and 1/10 in weight.

• Progress in Superconductivity and Cryogenics
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• v.19 no.4
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• pp.40-44
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• 2017

This paper analyzed the fault current limiting characteristics of the previously proposed transformer superconducting fault current limiter (TSFCL) interruption system according to its transformer type. The TSFCL interruption system is an interruption technology that combines a TSFCL, which uses a transformer and a superconductor, and a mechanical DC circuit breaker. This technology first limits the fault current using the inductance of the transformer winding and the quench characteristics of the superconductor. The limited fault current is then interrupted by a mechanical DC circuit breaker. The magnitude of the limited fault current can be controlled by the quench resistance of the superconductor in the TSFCL and the turns ratio of the transformer. When the fault current is controlled using a superconductor, additional costs are incurred due to the cooling vessel and the length of the superconductor. When the fault current is controlled using step-up and step-down transformers, however, it is possible to control the fault current more economically than using the superconductor. The TSFCL interruption system was designed using PSCAD/EMTDC-based analysis software, and the fault current limiting characteristics according to the type of the transformer were analyzed. The turns ratios of the step-up and step-down transformers were set to 1:2 and 2:1. The results were compared with those of a transformer with a 1:1 turns ratio.

• Progress in Superconductivity and Cryogenics
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• v.6 no.4
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• pp.37-40
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• 2004

A 1 MV A single phase high temperature superconducting (HTS) transformer was manufactured and tested. The rated voltages of primary and secondary of the HTS transformer are 22.9 kV and 6.6 kV respectively. BSCCO-2223 HTS tape was used for HTS windings of 1 MV A HTS transformer. In order to reduce AC loss generated in the HTS winding, the type of concentric arrangement winding was adopted to a 1 MV A HTS transformer. Single HTS tape for primary windings and 4 parallel HTS tapes for secondary windings were used considering the each rated current of the HTS transformer. A core of HTS transformer was fabricated as a shell type core made of laminated silicon steel plate. And a GFRP cryostat with a room temperature bore was also manufactured. The characteristic tests of 1 MV A HTS transformer were performed such as no load test, short circuit test and several insulation tests at 65 K using sub-cooled liquid nitrogen. From the results of tests, the validity of design of HTS transformer was ascertained.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.11a
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• pp.484-487
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• 2002

The mold transformers have been widely used in underground substations in large building and have some advantages in comparison to oil-transformer, that is low fire risk, excellent environmental compatibility, compact size and high reliability. In addition, the application of mold transformer for outdoor is possible due to development of epoxy resin. The mold transformer generally has cooling duct between low voltage coil and high voltage coil. A mold transformer made by one body molding method has been developed for small size and low loss. In this paper, the proto type mold transformer of 50kVA class is investigated by routine, type, special test. The outdoor energized aging test is investigated by back-to-back method to verify the long time performance of pole mold transformer. The aging process of transformer is analyzed by various diagnosis method such as DC voltage-current test, $tan{\delta}$, Meggar measurement, winding temperature and etc.

• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.9 no.4
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• pp.86-92
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• 1995

In the analysis of characteristic behaviors of a real transformer with coupling coefficient K is less than 1, this paper presents the more accurate and practical profits than the traditional analysis of the transformer treated as K∼1. This results from the use of the coupling coefficient type equivalent circuit of the transformer which includes K as positive parameter. Furthermore, a leakage transformer is analyzed in a unified method and the results of analysis are consistent with the practical measurements of the transformer. By using the above equivalent circuit, the characteristics referred to the load side are expressed as Thevenin voltage source and the leakage inductor (1-K2)L2. Therefore, these analysis about the output voltage and the damping factor in the transient state which are affected by the leakage inductor are confirmed to be an effective method.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.11a
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• pp.112-116
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• 2007

Highly damped insulation panel for transformer construction is needed in residential area because the making noise from transformer substation in inner city is appeared a lost of problem by increasing to conserve living environment. Therefor in this paper, the vibration and noise characteristic effect of cork-type and sponge-type that is attached between insulation panel and enforce beam in transformer is analized using real size transformer experimentally.

• Proceedings of the KIPE Conference
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• 2000.07a
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• pp.90-94
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• 2000

A conventional power supply to drive a microwave oven has ferro-resonant transformer and high voltage capacitor(HVC). Though it is simple transformer is bulky heavy and has low-efficiency. To improve this defect a high frequency switching inverter-type power supply has been investigated an developed. in recent years. But because of it's additional circuit and devices inverter-type power supply is more expensive than conventional one. In this paper The design procedure of a novel HVC embedded high frequency transformer is proposed for down-sizing and cost reduction. Also transformer equivalent circuit model is derived by FEM analysis and parameter measurements. And the operation of proposed HVC embedded transformer is verified by simulation and experimental results.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.11a
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• pp.367-370
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• 2004

This paper present a new disk-type piezoelectric transformer. The input side of the transformer has a crescent-shaped electrode and the output side has a focused poling direction. The piezoelectric transformers operated in each transformer's resonance vibration mode. The electrodes and poling directions on commercially available piezoelectric ceramic disks were designed so that the planar or shear mode coupling factor $(k_p,\;k_{15})$ becomes effective rather than the transverse meed coupling factor $(k_{31})$. A single layer prototype transformer, 26[m] in diameter and 2.0[mm] thickness, was fabricated, such as step-up ratio, power transformation efficiency and temperature were measured.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.1
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• pp.81-87
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• 2016

An LCL-type Isolated dc-dc converter operating for constant output voltage is analyzed, including the effect of a high frequency transformer using ac complex circuit approximation. Its solution is derived and is used to obtain the characteristics of the proposed converter. The analyses show through converter modeling, phasor diagram and gain comparison that inclusion of a high frequency transformer results in introduction of magnetizing inductance and leakage inductances at conventional LCL dc-dc converter with ideal transformer. The theoretical and simulation results are presented in case of the wide variations in input voltage and load current in detail. Analysis and simulation results observed that introduction of a transformer in the dc-dc converter had considerable effect on the performance, especially in the case of low output voltage and large load.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.250-250
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• 2007

In this paper, multilayer piezoelectric transformer for high power is presented. This piezoelectric transformer, with a multilayered construction in the thickness direction, was fabricated at the sintering temperature of $1055^{\circ}C$. The electrical properties of multilayer piezoelectric transformer as a function of Internal electrode structure, with same size, were investigated. Also, the multilayer piezoelectric transformer with different layer number of 5, 10, 15 layers, were investigated.