• 한국전자파학회논문지
• /
• 제21권5호
• /
• pp.537-543
• /
• 2010

본 논문에서는 단일 DGS를 사용하여 다중의 주파수 대역을 억압할 수 있는 슬롯형 DGS를 제안하였다. 제안된 구조는 동일 평면 도파관 전송 선로(CPW: Coplanar Waveguide)의 접지 면에 서로 다른 크기의 맴돌이 형태의 슬롯 DGS들을 신호 선에 대하여 횡축으로 삽입하여, 다중 주파수 대역을 억압할 수 있도록 설계되었다. 제안된 구조를 제작하였으며, 시뮬레이션 결과와 측정된 결과가 상당 부분 일치하는 것을 확인하였다. 또한 제안된 구조에 대한 등가 회로 모델을 제시하였다. 제안된 등가 회로는 접지 면에 위치한 DGS를 LC 공진기들로 표현하였으며, 이러한 공진기들이 신호선과 자기적으로 결합한 것으로 모델링 하였다. 등가 회로를 해석하여 다중의 공진 주파수 특성이 나타남을 확인하였다.

• 전력전자학회논문지
• /
• 제18권6호
• /
• pp.593-600
• /
• 2013

The asymmetric pulsed DC reactive magnetron sputtering system is widely used for the high quality plasma sputtering process such as a thin film deposition. In asymmetric pulsed DC power supply a reverse voltage is applied to the target periodically to minimize arc discharging effect. When sputtering in the mid-frequency range (20-350 kHz), the periodic target voltage reversals suppress arc formation at the target and provide long-term process stability. Thus, high quality, defect-free coatings of these materials can now be deposited at competitive rates. In this paper, a new style asymmetric pulsed DC power supply including mid-transformer is presented. In the proposed, an energy recovery circuit is adopted to reduce the mutual inductance of the transformer. As a result, the system dynamics of the voltage control loop is increased highly and the non-linear voltage boosting effect of the conventional system is removed. This work was proved through simulation and laboratory based experimental study.

• 대한의용생체공학회:학술대회논문집
• /
• 대한의용생체공학회 1997년도 춘계학술대회
• /
• pp.227-229
• /
• 1997

A new phased-array quadrature RF coil for one or two RF acquisition channels is developed for spine MR imaging. Quadrature RF coils for MRI have been useful to improve the signal-to-noise ratio (SNR) by $"\sqrt{2}"$ using two orthogonal RF coils in combination [1]. More recently, the phased-array RF coil has been proposed for more improvement of SNR by using an array of RF coil elements with a reduced size and coverage for each element. Two new schemes are proposed for the new phased-array quadrature RF coil as follows : (1) Proper overlapping of two quadrature RF coils thus removing the mutual inductance and (2) Attaching preamplifiers right after the coil section and combining the signal with proper phase delays. The coil has been implemented for receive- only mode. It has been tested through phantom and volunteer imaging. The experimental results show the utility of the proposed RF coil.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2006년도 제37회 하계학술대회 논문집 A
• /
• pp.593-594
• /
• 2006

High temperature superconducting(HTS) power cable is expected to be used for power transmission lines supplying electric power for densely populated cities in the near future. Commercializing of HTS power cable is coming. Simulation is required for safety before install of HTS power cable, a fabrication model used at the power system simulation. In this paper, we shows a single line-to ground fault analysis in the grid system which has a loom length HTS power cable. The authors developed a single line-to ground fault current calculation method which is considering the shield layer of HTS power cable. In the calculation, the T type equivalent circuit is used to derive the mutual inductance of the HTS power cable

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2006년도 제37회 하계학술대회 논문집 D
• /
• pp.2225-2226
• /
• 2006

High temperature superconducting(HTS) power cable is expected to be used for power transmission lines supplying electric power for densely populated cities in the near future. Commercializing of HTS power cable is coming. Simulation is required for safety before install of HTS power cable, a fabrication model used at the power system simulation. In this paper, we shows a single line-to ground fault analysis in the grid system which has a loom length HTS power cable. The authors developed a single line-to-ground fault current calculation method which is considering the shield layer of HTS power cable. In the calculation, the T type equivalent circuit is used to derive the mutual inductance of the HTS power cable.

• Journal of Magnetics
• /
• 제20권4호
• /
• pp.394-399
• /
• 2015

Electromagnetic Induction Launchers (EIL) have been receiving great attention due to their advantages of non-contact between the coils and a projectile. This paper describes the modeling and design of 3-stage EIL to accelerate a copper projectile of 50 kg with 290 mm diameter. Our EIL consists of three independent driving coils and pulsed power modules to generate separate driving currents. To find efficient acceleration conditions, the appropriate shape of the driving coils and the position of the projectile have been calculated by using a finite element analysis (FEA) method. The results showed that the projectile can be accelerated more effectively as the gap between the coils is smaller; a final velocity of 45 m/s was obtained. The acceleration efficiency was estimated to be 23.4% when a total electrical energy of 216 kJ was discharged.

• 제어로봇시스템학회논문지
• /
• 제16권10호
• /
• pp.975-981
• /
• 2010

Existing error compensation method of industrial electronic absolute displacement detector only depends on skilled engineers. This paper proposes a new table method in order to automatize error compensation. An waveform changes according to the parallel resistance for each pole were tabularized and four waveforms were superimposed to minimize total phase error. These process was verified using simulink. As a result of applying proposed method to the real sensor, peak to peak error was reduced from $3.428^{\circ}$ to $0.879^{\circ}$. In this case, compensation resistance is $4.7k\Omega$ in B pole and $20k\Omega$ in C pole. This compensation rate is comparable to skilled engineers, and it takes 0.8 second which is far shorter than 15 minutes when expert does.

• 전기학회논문지
• /
• 제59권10호
• /
• pp.1803-1808
• /
• 2010

Electric railway system consists of rolling stock, track, signal and catenary system. ATP system in railway signaling system is the important one grasping the position and velocity of a train. The wayside device of ATP system is installed between rails. Recently, the research about increasing train speed has been developed in total departments of the railroad systems. The study on the information transmission between on-board device and wayside device is required for increasing the train speed in the ATP system. When the train speed is increased as to same transmission distance, the problem on information transmission occurs because the transmission time is decreased. In case that the transmission distance is extended, the transmission time is decreased with respect to the train speed. Therefore, we have to define the standard magnetic field intensity as to the train speed in order to transmit correctly telegram. In this paper, the transmission distance for the telegram is suggested on the basis of the train speed. Also, the standard magnetic field intensity from the wayside device to on-board device is proposed by using transmission distance regarding the train speed in the ERTMS/ETCS system by using Matlab program. Also, BER according to the train speed is presented by calculating electric field intensity from the magnetic field intensity.

• Journal of Electrical Engineering and Technology
• /
• 제10권3호
• /
• pp.983-989
• /
• 2015

Power transformer is one of the major and key apparatus in electric power system. Monitoring and diagnosis of transformer fault is necessary for improving the life period of transformer. The failures caused by short circuits are one of the causes of transformer outages. The short circuit currents induce excessive forces in the transformer windings which result in winding deformation affecting the mechanical and electrical characteristics of the winding. In the present work, a transformer producing only the radial flux under short circuit is considered. The corresponding axial displacement profile of the windings is computed using Finite Element Method based transient structural analysis and thus obtained displacements are compared with the experimental result. The change in inter disc capacitance and mutual inductance of the deformed windings due to different short circuit currents are computed using Finite Element Method based field analyses and the corresponding Sweep Frequency Responses are computed using the modified electrical equivalent circuit. From the change in the first resonant frequency, the winding movement can be quantified which will be useful for estimating the mechanical withstand capability of the winding for different short circuit currents in the design stage itself.

• 한국정보통신학회:학술대회논문집
• /
• 한국정보통신학회 2012년도 추계학술대회
• /
• pp.573-576
• /
• 2012

고속 전철의 전력 공급 시설인 급전소와의 이격거리에 따른 전력 유도의 영향을 분석하기 위하여 전남 장성과 임곡간 10km 구간에 대하여 1km의 단위 구간으로 분할하여 통신 케이블을 고속 전철 선로와 인접하여 병행 포설한 후 고속 전철이 통과하는 시간 동안의 유도 종전압을 측정하고 이를 분석하였다. 정확한 분석을 위하여 지형적 특성 상 1km 단위의 구간 분할이 어려운 개소에서 측정된 유도 전압에 대하여 1km 구간으로 정규화 하였으며 또한 각 개소에서의 대저저항률 및 통신선과 전차선간 이격거리를 이용하여 계산되는 상호인덕턴스 역시 임의의 기준 값으로 정규화 하여 분석을 수행하였다.