• 한국전자파학회논문지
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• 제20권4호
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• pp.333-343
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• 2009

이상적인 전송선을 가정하고 도출된 여파기 설계 공식에 의하여 대역여파기를 설계할 경우, 제작된 여파기는 중심 주파수의 이동 및 주파수 특성의 왜곡을 발생시키며, 주파수가 높아질수록 심각한 문제를 야기한다. 이를 해결하기 위하여 본 논문에서는 개별 공진기의 EM(Electro-Magnetic) 시뮬레이션을 기초로 한 새로운 여파기 설계 방법을 제안하였다. 이 방법은 여파기를 개별 공진기로 분리하고, EM 시뮬레이션을 통해 개별 공진기의 리액턴스(reactance) 기울기 및 인버터 상수와 같은 여파기 설계 파라미터를 추출한 후, 이것이 인버터와 리액턴스 기울기로 구성된 인버터-기준형 설계치와 같도록 조정하는 것이다. 이와 같이 조정된 공진기를 조합하여 구성된 여파기는 별도의 조정 없이 목적한 설계치를 만족하게 된다. EM 시뮬레이션 시 이미 선로의 분산(dispersion) 및 불연속(discontinuity) 효과를 고려하였기 때문에 더 이상의 조정이 필요 없으며, 이 방법은 인버터-기준형으로 환원되는 대부분의 여파기에 적용 가능하다. 본 논문에서는 5단 SIR 여파기를 예로 들어 여파기 설계의 전반적인 과정을 설명하였고, 평행결합선로 여파기(parallel coupled line filter) 및 hair-pin 여파기에 확장 적용한 예를 보여 이 방법의 타당성을 보였다.

• 제어로봇시스템학회논문지
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• 제17권4호
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• pp.321-327
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• 2011

This paper proposes an equipment and an algorithm for modeling the magnetic force of electromagnets in magnetic levitation systems. We assume that the magnetic force model is represented in terms of a 2D lookup table. The 2D lookup table is constructed by applying noncausal filtering and interpolation to data measured by the proposed modeling equipment. The proposed modeling equipment is designed such that it can measure the magnetic force exerted on the levitation object while it changes the voltage applied to the electromagnet and position of the levitation object. The algorithm of making a 2D lookup table has two stages. The data measured by the proposed modeling equipment is smoothed by a noncausal filter and then the 2D lookup table is obtained by interpolating filtered data. The proposed modeling method has advantages of time-saving, model consistency, and chance of automation for mass production. We show the validity of proposed method through control experiments.

• 조명전기설비학회논문지
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• 제25권8호
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• pp.99-105
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• 2011

This paper is about the design of 3-axis magnetic sensor module which detects parking and moving vehicle. For the sensor module, MR Sensor from Honeywell of which maximum measurement range is ${\pm}2$[G] is used. It also consisted of amplifier and sensor filter and fabricated $30{\times}50$[mm] PCB. Fabricated sensor module produced helmholtz coil of which the length is 1.2[m] of 3-axis to know the performance. It installed sensor module at the center and measured the detected magnetic field. In result, 3-axis were detected as 0.2~0.3[mG] and the drift of the fluctuation of magnetic field was stabilized at 0.03[mG] unit. For the performance evaluation of the vehicle detection, after the entry and parking of the vehicle, variation of magnetic field was measured as 0.323~0.695[G] which the average 0.5[G] of the earth magnetic field was the center and the range of variation was confirmed as 0.37[G]. Therefore, the designed magnetic sensor can be used as the vehicle detection sensor module.

• 한국인터넷방송통신학회논문지
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• 제16권4호
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• pp.47-52
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• 2016

본 연구에서는 고고도 핵폭발에 기인한 HEMP의 영향으로부터 민간시설의 적합한 보호를 위한 HEMP 보호용 전원선 필터 구현 필요성을 다루기 위해, HEMP 관련 국방 규격 분석 및 바리스터, 관통형 커패시터, 가스방전관, 인덕터 등의 주요 소자들에 대한 분석을 수행하고, 이를 기반으로 단상 220VAC/16A 용량의 HEMP용 전원선 필터를 간이 제작하였다. 또한 배선용 차단기, 서지 보호기, EMI 필터 등과의 MIL-STD-188-125 PCI 규격 기반의 비교 실험을 수행하였다. 결과적으로 HEMP에 의한 전도성 노이즈로부터 시스템을 보호하기 위해서는 HEMP 보호 전용 필터의 개발이 필수조건임을 확인하였다.

• Transactions on Electrical and Electronic Materials
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• 제15권4호
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• pp.230-234
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• 2014

Automatic detection of disease helps medical institutions that are introducing digital images to read images rapidly and accurately, and is thus applicable to lesion diagnosis and treatment. The aim of this study was to apply a symmetry contribution algorithm to unsharp mask filter-applied MR images and propose an analysis technique to automatically recognize brain tumor and edema. We extracted the skull region and drawed outline of the skull in database of images obtained at P University Hospital and detected an axis of symmetry with cerebral characteristics. A symmetry contribution algorithm was then applied to the images around the axis of symmetry to observe intensity changes in pixels and detect disease areas. When we did not use the unsharp mask filter, a brain tumor was detected in 60 of a total of 95 MR images. The disease detection rate for the brain was 63.16%. However, when we used the unsharp mask filter, the tumor was detected in 87 of a total of 95 MR images, with a disease detection rate of 91.58%. When the unsharp mask filter was used in the pre-process stage, the disease detection rate for the brain was higher than when it was not used. We confirmed that unsharp mask filter can be used to rapidly and accurately to read many MR images stored in a database.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 하계학술대회 논문집 Vol.4 No.2
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• pp.751-755
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• 2003

In this paper, We proposed compact multi-layer LTCC (Low Temperature Cofired Ceramic) bandpass filter for Bluetooth module. A ${\lambda}/4$ coupled stripline resonators are designed, which composed of coupled strip-line section and loading capacitance. This resonator with a loading capacitor has slow-wave characteristics. Due to the slow-wave effect of the proposed resonator, it is possible to design and fabricate a compact bandpass filter with a wide upper stop band. Attenuation poles in the lower stop band are achieved using controlling of electro-magnetic coupling between resonators. Using multi-layer LTCC technology, we designed and fabricated band pass filter with a finite attenuation pole and wide upper stopband. The overall size of the filter is $1.2{\times}2.0{\times}1.0mm^3$.

• 한국인터넷방송통신학회논문지
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• 제12권1호
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• pp.173-179
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• 2012

본 연구에서는 국내 T-DMB 시스템에서 대역통과필터 기능을 수행 하는 cavity 필터를 설계하고자 HFSS 툴을 사용하여 그 특성을 시뮬레이션 하였으며, 이를 활용하여 필터를 제작하여 측정한 특성을 시뮬레이션 결과와 비교하였다. 전자계 3D 시뮬레이션 Tool인 HFSS를 사용하여 cavity 필터를 시뮬레이션 하는 것은, 실제로 필터를 제작하기 전에 성능을 미리 점검함으로서 최적화된 모델을 구축하여 시간과 비용을 최대한 절약할 수 있도록 하는 것이다. 원통형 도파관의 특성을 파악하여 필터의 최적의 조건들을 얻도록 연구하였으며, 이를 바탕으로 HFSS 시뮬레이션 및 제작을 하여 특성을 측정하여 설계값과 비교하였다.

• 한국재료학회지
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• 제15권2호
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• pp.106-111
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• 2005

Effects of stainless steel-making dusts and binder content on compacting $density(\rho)$ and magnetic properties were evaluated. Cores compacted with the mixture of pure Fe powders, $5wt.\%$ dusts and $0.25wt.\%$ binder showed good AC magnetic properties. For example, permeability$({\mu}a)$ and core loss(P) of the cores containing $5wt.\%$ dusts at 500 kHz were 62 and $4008\;{\mu}W/cm^3$, respectively. These properties are almost equivalent to those of competitor's products (i.e, Ancorsteel TC 80 produced by $H\ddot{o}gan\ddot{a}s$ Corp.). The powdered cores obtained from the present work are expected to apply for high-performance soft magnetic components such as normal mode choke filter and pulse transformer.

• KIEE International Transactions on Power Engineering
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• 제3A권2호
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• pp.70-78
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• 2003

This paper describes a transformer protection relay based on induced voltages. The ratio of the induced voltages of the primary and secondary windings is equal to the turns ratio during normal operating conditions such as magnetic inrush, overexcitation, and steady state, but it differs from the turns ratio in the case of internal faults. For a single-phase and a three-phase Y-Y transformer, the induced voltages are estimated and the ratios are compared with the turns ratio. For three-phase Y-Δ transformers, the differences between the induced voltages are estimated to use the line currents because delta-winding currents are practically unavailable. The proposed relay is tested under various conditions such as magnetic inrush, internal winding faults, overexcitation, and different core characteristics. The results evidently indicate that the relay successfully discriminates internal faults from magnetic inrush and overexcitation. This paper concludes by implementing the relay into a TMS320C6701 digital signal processor and reports satisfactory results. The relay requires no hysteresis data and can reduce the operating time of a relay.

• Journal of information and communication convergence engineering
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• 제21권4호
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• pp.316-321
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• 2023

In this study, we developed a conversion core that produces power by utilizing the unused magnetic field in a switchboard. The conversion core makes it possible to utilize power that is normally wasted. The conversion core is composed of a core, filter, and battery. A prototype was installed in a switchboard to conduct tests on the output, battery storage, and output boosting of multiple batteries. Energy was harvested from the magnetic field generated by a busbar of the switchboard, and the power conversion ratio of the core yielded 1.08-1.01 mW per 1 A of bus current. Supplying this technology to the market after further R&D and commercialization is expected to greatly assist in the dissemination of energy harvesting, which has not yet spread widely to the general public.