• Journal of the Korean Magnetics Society
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• v.11 no.6
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• pp.239-244
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• 2001

Recently, RF inductor having researched by many workers, we fabricated and investigated properties of RF inductors. In order to improve the Q-factor (Quality), we try to apply the patterned Fe$_{78.81}$Ta$_{8.47}$N$_{12.71}$ soft magnetic thin film of 5000 which shows magnetic anisotropy of 30 Oe. Thus, patterned magnetic film was artificially increased magnetic anisotropy lead to increasing of ferro-magnetic resonance frequency up to GHz band. Coil as part of inductor was fabricated by lift off process. The dimension of RF inductor was designed 47un, rectangular shape, and measured properties. In the case of Ti/Ag air core type inductor shows Q of 9, inductance of 8.4 nH at 2 GHz. Magnetic film employed inductor shows inductance of 9 nH and FMR resonance frequency was 700 MHz.

• Journal of the Korean Magnetics Society
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• v.26 no.4
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• pp.137-141
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• 2016

There is a growing demand for non-contact current measurements for efficient use of electrical power and energy saving. In this study, I propose a non-contact current sensor using LC resonance by a resonance circuit composed of a sensor coil and 2 coupling coils for enabling a wireless measurement. The inductance of the sensor coil, which could be changed by applied current, causes the change of resonance frequency of the resonance circuit. A pair of magnet was attached to the ferrite core to apply a bias magnetic field that enabled the determination of the current direction. We obtained an output voltage change of 18 V with the current of -3~3 A. But, the output was nonlinear. In order to realize the non-contact current measuring method proposed in the present study, there is a need for a strict investigation of linearity and resolution for the future study.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.24 no.2
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• pp.168-179
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• 2013

The critical point analysis(CA) and impedance matching analysis(IA) are performed and compared for a 4-coil magnetic resonance wireless power transfer system. Because the operating frequency splits at short distance while the efficiency drops drastically at long distance in this system, the optimization technique is needed for either a specific distance or efficiency at the fixed frequency. CA uses the critical point where shows maximum efficiency in the entire range and IA uses the impedance matching technique to achieve maximum efficiency at the specific distance. Comparison result shows that IA is more efficient than CA. Also, it shows one side matching has a tradeoff relationship comparing to both side matching. By using four spiral resonant coils, the analysis was experimentally verified. The measured data agreed well with the calculated data.

• Journal of the Institute of Electronics and Information Engineers
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• v.52 no.6
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• pp.43-49
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• 2015

In this paper, we propose enhanced wireless power transfer system based on magnetic resonance for portable electronic device charging. Resonators were designed and fabricated for efficiency improvement and miniaturization through electromagnetism simulation using HFSS(High Frequency Structure Simulator). Impedance matching network is employed to minimize reflections that is caused by difference between input impedance and output impedance. Receiver IC that consist of rectifier and Low Drop Out(LDO) regulator were designed and fabricated to reduce power loss. This chip is implemented in $0.35{\mu}m$ BCD technology. A maximum overall efficiency of 73.8% is determined for the system through experimental verification.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.4
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• pp.2330-2334
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• 2014

In this study, we confirmed the frequency characteristics of planar spiral inductor based on non-contact method AC coupling for wireless signal transmission. The dielectric constant variation of the substrate does not directly effect the inductance of device but effect the electrostatic capacity of device. Therefore, its change self-resonance frequency. The thickness increment of the substrate increase inductance but decrease self-resonance frequency. Because, the thickness decrement of the substrate make the inside electrostatic capacity increment.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.5
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• pp.537-543
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• 2010

This paper presents a slot-shaped defected ground structure(DGS) which has multi-band rejection property. The proposed structure, in which the spiral slot-shaped defects with different size are aligned in the transverse direction to the guiding direction of the coplanar waveguide(CPW), provides multiple resonance frequencies. Compared with the simulated results, the band rejection characteristic is in good agreement with the measurement. Also, an equivalent circuit model of the proposed structure is presented, where the DGS on the ground plane is modeled as LC-resonators. This resonators are inductively coupled to the signal line through mutual inductance. From the equivalent circuit model, multi-band rejection property was derived.

• Journal of Ocean Engineering and Technology
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• v.11 no.3
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• pp.107-115
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• 1997

비성형 동력학계로 모델링된 부유수송체의 동적응답을 조사하고 그 운동의 안정성을 해석하였다. 종동요 모우드의 고유주파수가 횡동요 모우드의 고유주파수의 두배가 되는, 즉, 2:1 내부공진 혹은 자기계수공진인 조건하에서, 이부유수송체는 한 운동 모우드의 직접가진에 의해 간접가진된 다른 모우드가 대진폭 응답을 보일 수 있음을 밝혔다. 또항, 종동요 모우드의 감쇠력은 비교적 넓은 범위의 운동에 대해 선형적임에 반해, 횡동요 모우드의 감쇠력은 점성의 영향이 대단히 커서 비선형성이 대단히 강한 것으로 알려져 왔다. 이 문제를 수학적으로 모델링하기 위하여, 종동요 모우드의 운동방정식에는 선형및 제곱형의 합의 형태인 감쇠력 모형을 사용하였다. 다중척도법을 사용하여 이 두가지 운동 모우드의 주기적 응답및 그의 안정성에 미치는 제곱형 비선형 횡동요 감쇠력의 영향을 밝혔다. 조우주기가 횡동요 모우드의 고유주기와 근사한 경우에 대하여 이 비선형계의 응답을 구하고 주파수-응답 곡선으로 나타내었다.

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.16-17
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• 2015

본 논문에서는 자기 공명 방식을 이용한 10W급 무선 전력 전송 시스템을 제안하였다. 기존의 Mhz 대역의 자기 공명 방식과는 달리 본 논문에서는 100kHz 대역의 주파수를 이용한 시스템을 제안하여 송수신 코일 간의 거리와 효율을 증가시켰다. 본 논문에서 사용된 송수신 코일은 가로 세로 20cm로 크기와 모양이 같은 동일한 구조로 제작하였고, 20cm의 거리에서 약 50%의 전송 효율을 나타내었다. 수신기는 가변 커패시터를 사용하여 거리에 따라 달라지는 공진 주파수를 수동으로 찾을 수 있도록 설계하였다.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.5 no.4
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• pp.206-210
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• 2012

In this paper wireless power transmission is discussed. The concept of non-radiative magnetic coupled resonance type wireless power transmission was introduced by MIT team at 2007, non-radiative type has been focused by many researchers. Authors present design of circuit parameters including driving frequency and verify the design by computer simulation.

• Proceedings of the Korea Information Processing Society Conference
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• 2013.11a
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• pp.821-823
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• 2013

무선충전기술은 개인별로 사용하는 모바일기기가 늘어나 충전에 따른 문제로 필요성이 대두되면서 무선충전의 세계 시장은 매년 80%이상 성장할 것으로 예상된다. 무선충전기술은 크게 전자파가 근거리 자기장을 통해 하나의 매체에서 다른 매체로 이동하는 기술인 자기공진방식과 수 mm내외로 인접한 두 개의 코일에 유도전류를 일으켜 배터리를 충전하는 방식인 자기유도방식으로 나뉜다. 현재는 모바일 기기시장에서 무선충전기술에 대한 성장이 이루어지고, 자동차의 경우도 전기자동차의 보급과 맞물려 시장에 보급될 것으로 보여 무선전력전송기술은 미래가 기대되는 기술이라고 볼 수 있다. 이러한 시점에서 무선충전이 적용된 다양한 환경에서 발생할 수 있는 보안 위협 요소를 도출하고자 한다.