• 한국생산제조학회지
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• 제23권4호
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• pp.408-412
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• 2014

An electromagnetic launching system presents a viable projectile propulsion alternative with low cost and minimal environmental drawbacks. A coil gun system propels a projectile using an electromagnetic force and the system is mainly employed in military weapon systems and space launch systems. In this paper, we perform optimization design to improve the muzzle velocity by analyzing the sensitivity. The muzzle velocity, which is the most important design function variable, is affected by design variables including the number of axial turns in the electromagnetic coil, number of radial turns in the electromagnetic coil, initial distance between the projectile and the coil, inner radius of the electromagnetic coil, and length of the projectile. An orthogonal arrays matrix is configured, and a finite element analysis is performed utilizing the commercial electromagnetic analysis software MAXWELL. The muzzle velocity of the optimal design is 62.4% greater than that of the initial design.

• 한국전자파학회논문지
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• 제26권4호
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• pp.389-396
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• 2015

펄스 유도(Pulse Induction) 방식의 금속 탐지기 코일 설계에 대하여 살펴보았다. 0.3 mm, 0.5 mm, 1.0 mm의 직경을 갖는 도선과 $30cm{\times}30cm$ 및 $35cm{\times}35cm$ 크기의 유전체 탐지판을 이용하여 탐지 코일을 제작하였고, 코일 크기와 코일 감은 수 등의 파라미터 변화에 따른 코일 시정수 및 코일 전류 등의 특성을 살펴보았다. 도선의 직경, 코일 크기 및 코일 감은 수 변화에 따른 코일의 인덕턴스, 저항 및 시정수 값에 대하여 계산 결과와 측정 결과를 비교 분석하였다. 또한, 입력 펄스폭 변화에 따른 탐지 코일의 전류 변화에 대하여 계산 결과와 측정 결과를 비교 분석함으로써 펄스 유도 방식의 금속탐지기 코일 설계에 대하여 논하였다.

• 전기학회논문지
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• 제67권3호
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• pp.485-489
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• 2018

Studies have been actively conducted on the magnetic-resonance wireless power transmission (WPT) for commercialization. Such studies are essential for improving the transmission efficiency. In the magnetic-resonance WPT, the inductance (L) and capacitance (C) vary significantly depending on the design of the coils, and the efficiency sharply changes accordingly. To address this problem, studies on the coil design are required. In this study, the S-parameter characteristics according to the number of turns of the coil were analyzed to improve the efficiency of the superconducting WPT. Superconducting coils were designed, and the reflection coefficient ($S_{11}$) according to the turns was analyzed. It was confirmed that the power transmission characteristics were improved as the reactance approached $0{\Omega}$

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제51권6호
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• pp.267-272
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• 2002

This Paper deals with the short circuit tests of the three-Phase DC reactor type fault current limiter (FCL) in changing of turns ratio of transformers. The experiment of this paper is a preliminary step to develop the FCL's faculties for an application to high voltage transmission line. So, superconducting coil was made of Nb-Ti, low temperature superconductor, and the ratings of the power system of experimental circuit are 400V/7A class. A three-phase DC reactor type FCL consists of three transformers, six diodes, one superconducting coil and one cryostat. The important point of experimental analysis is transient period, the operating lagging time of circuit breaker. As the results of the experiment, the values are referred to the limitation rate about 77% and 90% when the turns ratio of transformer was 1:1 and 2:1 respectively.

• 전기학회논문지P
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• 제58권1호
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• pp.85-89
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• 2009

We investigated the quench characteristics in accordance with increase of turns number of trigger coil and shunt resistance of matrix-type superconducting fault current limiter (SFCL) with $2{\times}3$ array. The matrix-type SFCL consists of the trigger part to apply magnetic field and the current-limiting part to limit fault current. The fault current limiting characteristics according to the increase of magnetic field and applied voltage were nearly same. This is because the application of magnetic field hasn't an affect on total impedance of the SFCL. When turns number of a reactor increased, the voltage difference between two superconducting units in the current-limiting part according was decreased. The resistance difference generated in two superconducting units was also decreased. Therefore, we confirmed that the differences of the critical behaviors between superconducting units were reduced by application of magnetic field. By this results, we could decide the optimum turns number of reactor to apply magnetic field.

• KIEE International Transactions on Electrophysics and Applications
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• 제5C권3호
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• pp.124-130
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• 2005

In this paper, we designed a cylindrical type light source having an electromagnetic principle of inductively coupled plasma, and measured its electrical-optical properties. Using the transformer principle, an electrically equivalent circuit cylindrical type light source was analyzed. According to the parameters of electromagnetic induction, which were diameter of coil with cpO.3$\~$ 1.2mm, number of turns with 4$\~$ 12 turns, distance with 40$\~$ l20mm and RF power with 10$\~$ 150W, the electrical .md optical properties were measured. When the diameter of the coil was cp0.3mm, number of turns was 8 and distance was 40mm, and the maximum brightness of 29,730 cd/m$^{2}$ was shown with RF power l50W. The relationship between electromagnetic induction and plasma discharges was demonstrated using the mode transition from E-mode to H-mode

• 한국전자파학회논문지
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• 제27권4호
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• pp.335-341
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• 2016

본 논문에서는 최대 무선전력전송 효율 구현에 필요한 최적 부하저항을 수신기 입력 임피던스(통상 $50{\Omega}$)에 바로 정합하기 위하여 수신 코일의 권선 수를 제어하는 방법을 제안한다. 수신 코일 권선 수와 도선 사이의 근접 효과가 고려된 최적 부하저항의 수식에 따라 수신 코일을 설계, 제작 및 측정하였다. 이론과 EM 시뮬레이션, 측정을 통하여 최적 부하 저항과 효율을 비교한 결과 비교적 잘 일치함을 확인할 수 있었다. 본 논문의 결과를 활용하면 별도의 급전 루프 없는 단순하고 부피가 작은 2-coil 시스템으로도 허용된 최대 전력을 구현할 수 있다.

• 융합신호처리학회 학술대회논문집
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• 한국신호처리시스템학회 2003년도 하계학술대회 논문집
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• pp.251-255
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• 2003

In this paper, we have a fluxgate sensor with ferrite core. Thought sensor is consist of one excitation coil and two pick-up coil, and A lock-in amplifier circuity is designed for Signal processing of picking up 2nd harmonics from pick-up coils. Excitation coils is turned by 20 turns, and pick-up coil for picking up harmonics is turned by 40 turns eachother. It convert 2nd harmonics to DC output voltage. Measured output voltage and sensitivity, direction of sensor about out side magnetic field, and also sensor output properties about excitation frequency and current.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1988년도 전기.전자공학 학술대회 논문집
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• pp.399-401
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• 1988

This paper describes the experiment and design of Rogowski - wound coil used to measure a pulsed current with pulsewidth on the order of 100nsec in the kiloampere range. Radius of coil is 2.75cm, total number of turns are 26 and cross -sectional area is 1 cm. The coil have 3ns rise time, 0.2nsec transit time and sensitivity is 4v/kA.

• 한국전기전자재료학회논문지
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• 제18권8호
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• pp.772-778
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• 2005

In this paper, we designed the cylindrical type light source that had a electromagnetic principle of inductively coupled plasma, and measured its electrical-optical properties. Using the principle of transformer, electrically equivalent circuit of cylindrical type light source was analyzed. According to the parameters of electromagnetic induction which were diameter of coil with $0.3\~1.2\;mm{\Phi}$, number of turns with $4\~12$ turns, distance with $40\~120$ mm and RF power with $10\~150$ W, the electrical and optical properties were measured. When diameter of coil was $0.3\;mm{\Phi}$, number of turns was 8 turns and distance was 40 mm, the highest brightness of 29,730 $cd/m^2$ was shown with RF power 150 W. The relationship between electromagnetic induction and plasma discharges was shown by mode transition from E-mode to H-mode.