• 한국전자파학회논문지
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• 제14권1호
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• pp.14-19
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• 2003

본 논문에서는 λ/4 hair-pin 공진기를 이용한 LTCC MLC 대역통과 여파기를 제안하였다. λ/4 hair-pin 공진기는 부분적인 평행 결합선로와 그 선폭이 동일한 전송선로로 구성되어, 등가적으로 SIR이 되므로 기존의 SIR과 달리 구조적인 불연속 없이 공진기의 크기를 소형화할 수 있다. 부가적인 용량성 결합을 포함한 λ/4 hair-pin 공진기를 이용한 LTCC MLC 대역통과 여파기의 등가회로를 유도하고, 설계 절차를 기술하였다 1.8 GHz대역에서 2단의 대역통과 여파기를 설계, 제작하였다.

• Journal of Electrical Engineering and Technology
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• 제6권1호
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• pp.111-118
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• 2011

In recent years, various types of partial discharge (PD) methods such as capacitive, inductive, electromagnetic, and acoustic coupling techniques have been developed for diagnosing rotating machines. An electromagnetic (EM) probe, which is an inductively coupled type of sensor, is required for detecting corona and internal discharges during off-line tests. In this study, a new technique for enhancing the measurement sensitivities for corona and internal discharge based on an EM inductive position sensor is proposed. An EM probe that winds wires around horseshoe-shaped and cylindershaped ferrites as helices is designed and optimized for the implementation of off-line PD monitoring of the stator winding of a rotating machine. The measurement system based on this design is implemented, and it is verified from the results of the experiment performed in this study that the probe provides similar performance as existing commercial products.

• 한국전자파학회논문지
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• 제7권2호
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• pp.95-104
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• 1996

임의의 평면파가 각진 두 도선에 입사시 관계변수들이 양단부하에 유기되는 전압에 미치는 영향을 조사하였다. 전송선 양단의 임피던스가 정합되고 입사파의 방향이 방위각과 고도각이 같을 때 유기전압이 최소가 됨을 알 수 있었다. 또한, 도선의 반경이나 도선간의 경사각이 변할 때 도표상에서 유기전압을 계산할 수 있는 방안도 제시하였다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2011년도 춘계학술대회 논문집
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• pp.681-688
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• 2011

Structural model of laminated composite plates based on the first order shear deformable plate theory and subjected to a combination of magnetic and thermal fields is developed. Coupled equations of motion are derived via Hamilton's principle on the basis of electromagnetic equations (Faraday, Ampere, Ohm, and Lorenz equations) and thermal equations which are involved in constitutive equations. In order to obtain the implications of a number of geometrical and physical features of the model, one special case is investigated, that is, free vibration of a composite plate immersed in a transversal magnetic field. Special coupling effects between the magnetic and elastic fields are revealed in this paper.

• 한국전자파학회논문지
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• 제13권3호
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• pp.257-262
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• 2002

본 논문에서 60 ㎓ 대역용 도파관 급전 radial line slot array (RLSA) 안테나를 설계, 제작하였다. Ewald합 기법과 Shanks 변환을 이용한 효율적인 수치해석으로 RLSA 설계에 필수적인 슬롯을 통한 결합 특성을 계산하였고, 또한 기존의 급전 방식과는 달리 구형 도파관-radial line 변화구조를 이용한 구형 도파관 급전 구조를 사용하였다. 직경 10cm의 크기로 제작된 원형 안테나의 측정 결과 60 ㎓에서 31 ㏈i 의 이득과 38%의 효율을 나타내었다.

• Journal of electromagnetic engineering and science
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• 제1권1호
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• pp.88-94
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• 2001

In this paper, the lightning-induced voltages on shielded twisted-pair wires with multipoint grounding on cable sheath are calculated by using finite-difference time domain (FDTD) method. The equivalent single-wire line that represents a bundle of twisted-pair wires is adopted for computational efficiency. A finitely conducting ground is also taken into account in both lightning electromagnetic field calculations and surge propagation along the shielded cable for a practical simulation. It is found that multipoint additional grounding on cable sheath provides more shielding effectiveness especially in the early time response of the lightning-induced voltages. From this study, the requirements for lighting surge protection devices in a telecommunication subscriber cab1e can be established.

• Journal of electromagnetic engineering and science
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• 제11권3호
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• pp.156-160
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• 2011

We have proposed and analyzed an equivalent circuit for a magnetically coupled wireless power transmission (WPT) system between two loop resonators by considering its coupling coefficient and radiation-related parameters. A complete formulation is provided for all the necessary circuit parameters. The mechanism of radiation loss is sufficiently explained. The circuit and electromagnetic (EM) simulation results have been shown to be in good agreement. Based on the proposed circuit formulation, a specific load impedance for maximum WPT efficiency was found to exist. The proposed modeling of the WPT in terms of circuit characterizations provides sufficient insight into the problems associated with WPT.

• Journal of electromagnetic engineering and science
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• 제13권4호
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• pp.263-266
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• 2013

A novel compact and low-loss VHF bandpass filter is presented with enhanced stopband performance using metamaterial zeroth order resonator (ZOR) characteristics. An in-line ZOR filter is initially suggested and changed to have transmission zeros (TZs) due to source-load coupling for effective improvement of the isolation from UHF wireless channels. The proposed filter is smaller than 1/10 of the conventional filters in terms of size and has relatively very low insertion loss (< 1 dB for the electromagnetic (EM) simulation and < 3 dB for the measurement) and return loss (<-20 dB) in the passband due to the approximately 80% size reduction and the higher isolation in the stopband due to the TZs. The circuit and EM simulation are in good agreement with the measurements.

• Journal of electromagnetic engineering and science
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• 제16권3호
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• pp.194-197
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• 2016

An eight-element compact low-profile multi-input multi-output (MIMO) antenna is proposed for wireless local area network (WLAN) mobile applications. The proposed antenna consists of eight inverted-F antennas with an isolation-enhanced structure. By inserting the isolation-enhanced structure between the antenna elements, the slot and capacitor pair generates additional resonant frequency and decreases mutual coupling between the antenna elements. The overall size of the proposed antenna is only $33mm{\times}33mm$, which is integrated into an area of just $0.5{\lambda}{\times}0.5{\lambda}$. The proposed antenna meets 5-GHz WLAN standards with an operation bandwidth of 4.86 - 5.27 GHz and achieves an isolation of approximately 30 dB at 5 GHz. The simulated and measured results for the proposed antenna are presented and compared.

• 한국전자파학회논문지
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• 제16권7호
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• pp.661-670
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• 2005

본 논문에서는 $2\~6$ Hz의 광대역에서 -3 dB 결합 특성과 $90^{\circ}$ 위상차를 제공하는 마이크로스트립 하이브리드를 설계하였다. 3-단 결합기 구조를 가지며, 양 측면 단은 대칭 가장자리 결합 선로로 구현되는 반면에, 가운데 단은 수직으로 장착된 평면 회로로 구성된다. 특히 수직 장착된 평면 회로는 밀 결합 특성을 얻기 위해 일부 접지면이 제거된 형태를 갖는다. 본 하이브리드는 마이크로스트립 구조이기 때문에 제작이 용이하고, 수직 장착 기판을 특성 적정화의 조정점으로 이용함으로써 양호한 튜닝 유연성을 갖는다. 무엇보다도 제안한 하이브리드는 구조와 제작의 단순성에 비해 만족할만한 성능을 제공한다.