Magnetizing Characteristics of a Flux-Coupling Type Superconducting Fault Current Limiter Connected in Parallel between Two Coils Using an E–I Iron Core

고석철,한태희,임성훈 대한전기학회 2019 Journal of Electrical Engineering & Technology Vol.14 No.4

In power systems, there are short-circuit faults due to various causes. One way to reduce this fault current is the superconducting fault current limiter (SFCL). Since the current limiter model using a winding includes an iron core, the magnetizing current generated in the iron core when the fault current is limited should not be as large as possible. That is, when saturation of the iron core occurs, suffi cient magnetic fl ux is not generated and the fault current limiting characteristics are degraded. Therefore, in this paper, a fl ux-coupling type SFCL using an E–I iron core was fabricated to eff ectively reduce the saturation of the iron core and limit the fault current to twice. The two major windings N1 and N2 were connected in parallel, and the peak current limiting characteristics and voltage waveforms were compared based on the winding directions of the two coils. The two main coils were also connected in parallel to analyze the fl ux linkage and instantaneous power characteristics. The magnetization power area and operating range of the fl ux linkage based on the magnetic fl ux energy accumulated in the E–I iron core were compared and analyzed in relation to the increase or decrease of the magnetizing current.

전통마을의 문화지속성 평가 -경북 영천 선원리를 대상으로-

고석철,장병관 한국조경학회 2002 韓國造景學會誌 Vol.29 No.6

The purpose of this study is to establish a model of cultural sustainability in the traditional village. Cultural sustainability is being advanced by promoting the viability of traditional arts and the unique regional features of traditional culture, such as folklore, traditional landscapes, buildings and other environments of outstanding historical value. These cultural resources were also created or occurred at specific geographic locations at certain points in time by different individuals. The content of this study was to develop a model using indicators for cultural sustainability, and to apply and evaluate the model. In older to evaluate the model, Sonwon-ri village in Yongchon, located in Kyungsangbuk-do, was selected as the case study area. The major findings are as follows: 1) Sonwon-ri village has maintained the vernacular landscape except at the entrance of village. Also, the village people have pride and have adapted to the natural environment. 2) Sonwon-ri village has a self-sustaining system and circular network within its environmental capacity. Sonwon-ri village has many historical sites and buildings such as important folk resources, cultural assets, traditional houses and pavilions. 3) The people how the theory of fens-shui which interprets the location of village in relationship to a crane mountain with the village situated as a crane head. These symbolic and cultural elements have an important role in establishing the boundary of the village. From the research it can be seen that Sonwon-ri village kept many cultural sustainability indicators in terms of active factors, physical factors and psychological factors. By analysing the participation of different scientific disciplines and identifying disciplinary categories, this study provides a basis for understanding how cultural sustainability is subjected to research in the field of landscape planning and design.

다채널 고온 초전도 볼텍스 유동 트랜지스터의 I-V 특성 해석

고석철,강형곤,임성훈,최효상,한병성 한국전기전자재료학회 2003 전기전자재료학회논문지 Vol.16 No.10

The principle of the superconducting vortex flow transistor (SVFT) is based on control of the Abrikosov vortex flowing along a channel. The induced voltage is controlled by a bias current and a control current, instead of external magnetic field. The device is composed of parallel weak links with a nearby current control line. We explained the process to get an I-V characteristic equation and described the method to induce the external and internal magnetic field by the Biot-Savarts law in this paper. The equation can be used to predict the I-V curves for fabricated device. From the equation we demonstrated that the current-voltage characteristics were changed with input parameters. I-V characteristics were simulated to analyze a SVFT with multi-channel by a computer program.

전도성 AFM 탐침에 의한 YBa₂Cu₃O_7-x 스트립 라인의 산화피막 형성

고석철,강형곤,임성훈,한병성,이해성 한국전기전자재료학회 2004 전기전자재료학회논문지 Vol.17 No.8

Fundamental results obtained from an atomic force microscope (AFM) chemically-induced direct nano-lithography process are presented, which is regarded as a simple method for fabrication nm-scale devices such as superconducting flux flow transistors (SFFTs) and single electron tunneling transistors (SETs). Si cantilevers with Pt coating and with 30 nm thick TiO coating were used as conducting AFM tips in this study. We observed the surfaces of superconducting strip lines modified by AFM anodization' process. First, superconducting strip lines with scan size 2 ${\mu}{\textrm}{m}$${\times}$2 ${\mu}{\textrm}{m}$ have been anodized by AFM technology. The surface roughness was increased with the number of AFM scanning, The roughness variation was higher in case of the AFM tip with a positive voltage than with a negative voltage in respect of the strip surface. Second, we have patterned nm-scale oxide lines on ${YBa}-2{Cu}_3{O}_{7-x}$ superconducting microstrip surfaces by AFM conductive cantilever with a negative bias voltage. The ${YBa}-2{Cu}_3{O}_{7-x}$ oxide lines could be patterned by anodization technique. This research showed that the critical characteristics of superconducting thin films were be controlled by AFM anodization process technique. The AFM technique was expected to be used as a promising anodization technique for fabrication of an SFFT with nano-channel.

모의배전계통에 두 트리거 전류레벨을 이용한 초전도한류기의 전류제한 특성 분석

고석철,한태희,Ko, Seok-Cheol,Han, Tae-Hee 한국전기전자재료학회 2013 전기전자재료학회논문지 Vol.26 No.2

When the accident occurred in power distribution system, it needs to control efficiently the fault current according to the fault angle and location. The flux-lock type superconducting fault current limiters (SFCL) can quickly limit when the short circuit accidents occurred and be made the resistance after the fault current. The flux-lock type SFCL has a single triggering element, detects and limits the fault current at the same time regardless of the size of the fault current. However, it has a disadvantage that broken the superconductor element. If the flux-lock type SFCL has separated structure of the triggering element and the limiting element, when large fault current occurs, it can reduce the burden of power and control fault current to adjust impedance. In this paper, this system is composed by triggering element and limiting element to analyze operation of limiting current. When the fault current occurs, we analyzed the limiting and operating current characteristics of the two triggering current level, and the compensation characteristics of bus-voltage sag according to the fault angle and location.

Improvement of Current Limiting and Recovery Characteristics of Flux-Lock Type SFCL with Series Connection of Two Coils Using Its Third Coil

고석철,김영필,임성훈 대한전기학회 2017 Journal of Electrical Engineering & Technology Vol.12 No.1

In this work, the current limiting and recovery characteristics of a flux-lock type superconducting fault current limiter (SFCL) with series connection of two coils were effectively improved by adding a third winding into the conventional flux-lock type SFCL with series connection of two coils. To confirm the contribution of the third winding to the current limiting and recovery characteristics of this type of the SFCL, short-circuit testing was carried out with consideration of the third winding, and the effect of the third winding on the current limiting and recovery characteristics was examined by comparative analysis of the amplitude of the limited fault current and the power burden of the high-TC superconducting (HTSC) element comprising the SFCL. Through the analysis of both the limiting impedance and the operational current as the main design parameter of the SFCL, the improved current limiting and recovery characteristics of the flux-lock type SFCL using the third winding could be verified.

모의전력계통에 적용된 두 개의 자기결합 회로를 갖는 직렬연결형 초전도 전류제한기의 전류제한 특성 분석

고석철,이신원,Ko, Seok-Cheol,Lee, Shin-Won 한국전기전자재료학회 2013 전기전자재료학회논문지 Vol.26 No.1

The series connection-type superconducting fault current limiter (SFCL) with two magnetically coupled circuits was suggested and its effectiveness through the analysis on the current limiting and recovery characteristics was described. The fault current limiting characteristics of the proposed SFCL as well as the load voltage sag compensating characteristics according to the winding direction were investigated. To confirm the fault current limiting and the voltage sag suppressing characteristics of the this SFCL, the short-circuit tests for the simulated power system with the series connection-type SFCL were carried out. The series connection-type SFCL designed with the additive polarity winding was shown to perform more effective fault current limiting and load voltage sag compensating operations through the fast quench occurrence right after the fault appears and the fast recovery operation after the fault removes than that with the subtractive polarity winding.

변압기 권선을 이용한 자속구속형 초전도 전류제한기의 전류제한 및 전압강하 보상 특성

고석철,Ko, Seok-Cheol 한국전기전자재료학회 2012 전기전자재료학회논문지 Vol.25 No.12

The superconducting fault current limiter (SFCL) can quickly limit the fault current shortly after the short circuit occurs and recover the superconducting state after the fault removes and plays a role in compensating the voltage sag of the sound feeder adjacent to the fault feeder as well as the fault current limiting operation of the fault feeder. Especially, the flux-lock type SFCL with an isolated transformer, which consists of two parallel connected coils on an iron core and the isolated transformer connected in series with one of two coils, has different voltage sag compensating and current limiting characteristics due to the winding direction and the inductance ratio of two coils. The current limiting and the voltage sag compensating characteristics of a SFCL using a transformer winding were analyzed. Through the analysis on the short-circuit tests results considering the winding direction of two coils, the SFCL designed with the additive polarity winding has shown the higher limited fault current than the SFCL designed with the subtractive polarity winding. It could be confirmed that the higher fault current limitation of the SFCL could be contributed to the higher load voltage sag compensation.

ICP 식각 시스템에 의한 초전도 스트립 라인의 임계 특성 분석

고석철,강형곤,최효상,양성채,한병성 한국전기전자재료학회 2004 전기전자재료학회논문지 Vol.17 No.7

Superconducting flux flow transistor (SFFT) is based on a control of the Abrikosov vortex flowing along a channel. The induced voltage by moving of the Abrikosov vortex in an SFFT is greatly affected by the thickness, the width, and the length of channel. In order to fabricate a reproducible channel in the SFFT, we studied the variation of the critical characteristics of ${YBa}_2{Cu}_3{O}_7-\delta(YBCO)$ thin films with the etching time using ICP (Inductively coupled plasma) system. From the simulation, it was certified that the vortex velocity was increased in a low pinning energy at channel width 0,5 mm. The surfaces of YBCO thin film were etched by ICP etching system. We observed the etched channel surfaces by AFM (Atomic Force Microscope) and measured the critical current density with etching time. As a measured results, the etching thickness of channel should be optimized to fabricated a flux flow transistor with specified characteristics.

건설용 철근 20~70Φ급 자동 철근 결속기의 설계·제작에 대한 고찰

고석철,Ko, Seok-Cheol 한국조명전기설비학회 2016 조명·전기설비학회논문지 Vol.30 No.4

In general, the method of supplying the wire of auto-binding apparatus for reinforcing bar used in construction sites are often poor and supplies by using the hall way, the head of the thick binder is often an obstacle for interference when bind the reinforcing bar. In this paper, we proposed a new auto-binding apparatus for reinforcing bar by improving the existing bond issues that they work for the common descriptor. The auto-binding apparatus for reinforcing bar is easy to carry because it is designed with a pistol grip shape. It also has the advantage to increase the productivity because it is easy binding of the reinforcing bar itself, rather than binding operation by a person. It was designed and produced by adding a multi-functional to automatically bond the reinforcing rod of $20{\sim}70{\Phi}$ range. We carried out the performance evaluation tests, such as binding strength, binding time, binding range, body weight, wire cutting unit wear, binding malfunction test in order to compare and validate domestic and foreign technical level of the performance of the developed auto-binding apparatus for reinforcing bar. As a result, it was confirmed that the development of each item is reached.