• 한국전자파학회논문지
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• 제15권10호
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• pp.938-943
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• 2004

본 논문에서는 CPW에 식각된 T자형 DGS를 제안하고 전송이론을 이용하여 전파 방사를 포함한 손실률, BW(3-dB fractional bandwidth) 등을 closed-form 형태의 수식으로 유도하고 이의 영향에 대해 분석한다. 제안된 T자형 DGS 구조는 기존의 아령형 DGS 구조보다 약 5.5배정도 큰 커패시턴스(C) 조절 특성을 가진다. 또 DGS 등가회로의 R, L, C값과 손실률, BW, 저지대역 공진 각주파수($\omega_0$)의 상관관계를 정량적으로 이끌어낸다.

• 한국전자파학회논문지
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• 제11권8호
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• pp.1305-1312
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• 2000

본 논문에서는 Finitely Backed Conductor(FBC) CPW(Coplanar Waveguides) 구조를 이용한 대역 통과 필터를 제안한다. 특히, 마이크로 스트립 전송 선로와 비교하여 CPW구조의 단점인 적은 결합량 문제를 해결하기 위한 방법으로 구조적 변화를 통한 특성 향상을 소개한다. 본 논문에서는 FBC 구조를 이용하여 협대역 대역 통과 필터를 제안하였으며, 측정 결과를 통해 삽입 손실의 향상 효과를 확인할 수 있다. Finitely backed conductor(FBC)를 이용한 CPW 대역 통과 필터를 설계하기 위해 FEM 방식을 이용한 HP사의 HFSS 소프트웨어를 사용하였다.

• Journal of electromagnetic engineering and science
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• 제16권2호
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• pp.67-73
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• 2016

This paper presents simple expressions for the effective permeability of bulk metamaterial consisting of ring resonators (RRs) or split ring resonators (SRRs) based on the convenient geometrical factors of the structure compared with wavelength. The resonant frequency dependence of the medium permeability, including loss effects, is analyzed in detail. Inverting the analysis equations, useful design (or synthesis) equations are derived for a systematic design process with some examples. This paper may particularly be useful for the design of a bulk metamaterial with a specific negative relative permeability at a desired frequency. The loss of metamaterials consisting of RRs (or SRRs) is also analyzed over a wide frequency band from 10 MHz to 10 THz.

• Journal of electromagnetic engineering and science
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• 제8권1호
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• pp.12-16
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• 2008

In this paper, we introduce a coupling, which is achieved through the aperture instead of the conventional edge coupling, so that the bandpass filter is reduced less than half in size compared to conventional planar type. The resulting filter configuration has a near two-fold symmetry, where the aperture coupling is used in the middle of the coupling stages. We designed a bandpass filter using two tapped hairpin resonators, of which the order becomes four. The designed bandpass filter has the size of $8.9{\times}18.3\;mm$. It has the return loss better than 17dB and the insertion loss of less than 5 dB in overall passband. The measured results show good agreements with simulated ones.

• 대한전기학회논문지
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• 제31권12호
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• pp.173-179
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• 1982

This paper presents a modified quasi-static approximate solution derived from the Maxwell's equations of integral form for the calculation of magnetic shielding effectiveness in a non-uniform enclosure such as metal-clad high-voltage test laboratory. It also describes the simplified relationship between the electrical parameters applicable to the engineering calculations of electromagnetic absorption loss which comprise the resultant effects due to the welding seams and short-circuited slots as well as the shielding material properties. A numerical example shows the fairly good agreements with experimental results measured on the absorption loss vs. incident wave frequency without any unreasonable rapid increase.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제53권8호
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• pp.401-406
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• 2004

In this experimentation, we investigated the characteristics of electromagnetic wave absorption of ferroxplana powder and silicone rubber composite. Ferroxplana was prepared by flux method at low temperature. The crystallization, magnetic properties and particle morphology of the obtained ferroxplana powder were investigated by using XRD, VSM and SEM. The particle size of ferroxplana powder was 2∼4$\mu\textrm{m}$ at the ratio of R=26, The coercivity and saturation magnetization of ferroxplana powder increased slightly with increase of temperature, The magnetic loss was the main factor of electromagnetic wave absorption of ferroxplana powder and silicone rubber composite, The maximum reflection loss of composite was about -l5dB below 4GHz.

• Journal of Power Electronics
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• 제18권6호
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• pp.1901-1911
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• 2018

This study presents a circuit model for simulating the switching transients of insulated-gate bipolar transistors (IGBTs) with inductive load switching. The modeling approach used in this study considers the behavior of IGBTs and freewheeling diodes during the transient process and ignores the complex semiconductor physics-based relationships and parameters. The proposed circuit model can accurately simulate the switching behavior due to the detailed consideration of device-circuit interactions and the nonlinear nature of model parameters, such as internal capacitances. The developed model is incorporated in an IGBT loss calculation module of an electromagnetic transient simulation program to enable the estimation of switching losses in voltage source converters embedded in large power systems.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 추계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.93-95
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• 2008

Nowadays more attention is paid to the developing high efficiency electrical machines for energy saving and protection of natural resources. In general, the electromagnetic losses appearing in electrical machines are widely classified into copper loss, core loss and rotor loss. Particularly, in permanent magnet (PM) machines, core loss forms a larger portion of the total losses than in another machine. So, satisfactory prediction of core loss at the design or analysis stage of PM machines is essential to active high efficiency and high performance. This paper deals with analysis of magnetic field distribution due to geometry of stator core for magnetic core loss calculation of multi-pole PM synchronous machine.

• 한국전자파학회논문지
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• 제23권1호
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• pp.76-84
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• 2012

본 논문에서는 K-커넥터를 사용하지 않고 다수의 전력증폭기를 WR-28 도파관에서 전력 합성하기 위해 마이크로스트립 전송 선로를 도파관으로 직접 변환하는 2가지 형태의 개방형 E-평면 프로브를 최적 설계하고, 이를 활용한 변환기를 제작, 평가하였다. 중심 주파수 35 GHz에서 ${\pm}500MHz$의 대역폭을 가지며, 0.1 dB의 삽입 손실과 20 dB 이상의 반사 손실을 목표로 변환기 설계가 진행되었으며, 제작 시 발생할 수 있는 지그 가공 및 조립오차에 대한 특성도 3차원 전자기 시뮬레이션을 통해 고려하였다. 16 mm와 26.57 mm의 마이크로스트립 선로를 가지는 back-to-back 변환기 구조를 제작하였으며, 35 GHz에서 변환기 당 약 0.1 dB의 우수한 삽입 손실을 얻었고, Ka 대역 전체 주파수 영역에서 평균 0.2 dB의 삽입 손실 특성을 보였다. 반사 손실의 경우, back-to-back 구조가 Ka 대역에서 15 dB 이상의 특성을 보여 변환기 자체로는 20 dB 이상의 값을 가지는 것으로 파악되었다.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2000년도 전력전자학술대회 논문집
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• pp.78-81
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• 2000

The backlight inverter used in a laptop computer is investigated in this paper. It has been difficult for the electromagnetic transformer in the inverter to have a high efficiency and compact profile. In this study the piezoelectric transformer(PT) is used to reduce the loss and volume compared to the standard electromagnetic transformer. Comparison with the experimental inverter with the PT has been shown to validated the simulation program using the equivalent circuit model of the PT. A simple dimming control circuit was experimentally demonstrated and shown to have broad control.