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최학윤(Hak-Yun Choi) 한국조명·전기설비학회 2011 조명·전기설비학회논문지 Vol.25 No.7
In this paper, magnetic field compensation system with an open architecture and can be installed indoors is designed and measured by fabricated. To verify the shielding effectiveness, two rectangular helmholtz coils with 3-axis are fabricated to generate magnetic field and measured magnetic field inside compensation coil for 1~60[㎐], According to measurements, AC shielding effectiveness of compensation system is 96[%] of 1[㎐], 95[%] of 30[㎐] and 90[%] of 60[㎐]. The performance of system therefore can be used as the magnetically shielded room for medical and industrial field.
최학윤(Hak-Yun Choi) 한국조명·전기설비학회 2010 조명·전기설비학회논문지 Vol.24 No.9
In this paper, the shielding effectiveness of aluminum shielded room with using eddy-current is calculated and measured after fabricated. The size and thickness of shielded room are decided as 2.4 × 2.4 × 2.4[㎥] and 12[㎜] after AC shielding characteristics by eddy-current of conductive materials is analyzed. To verify the shielding effectiveness, a rectangular helmholtz coil is fabricated to generate magnetic field of 1.37[μT] and measured magnetic field inside shielding room for 0.01~10[㎐]. According to calculations and measurements, AC Shielding effectiveness by eddy-current in aluminum is very small for 0.01~2[㎐] and 5 times to 11 times for 5~10[㎐].
최학윤(Hak-Yun Choi),이형일(Hyeong-Il Lee) 한국조명·전기설비학회 2011 조명·전기설비학회논문지 Vol.25 No.8
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 ±2[G] is used. It also consisted of amplifier and sensor filter and fabricated 30×50[㎜] 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.
최학윤(Hak-Yun Choi) 한국조명·전기설비학회 2010 조명·전기설비학회논문지 Vol.24 No.6
본 논문에서는 0.1[Hz]에서 60[Hz]의 저주파 자기장을 차폐할 수 있는 경량의 자기차폐실을 설계하고, 차폐실을 제작하여 차폐율을 측정하였다. 자기차폐실의 크기는 산업용 측정기기가 들어갈 수 있는 3.0[m](W)× 3.0[m](L)×3.0[m](H)로 하였으며, 투자율이 높은 자성체의 직류차폐와 교류차폐특성, 도전성 물질의 와전류에 의한 차폐율을 계산하였고, 설계된 결과로부터 차폐실의 구조 값을 구하였다. 설계된 차폐실의 타당성을 검토하기 위하여 저주파 차폐실을 제작하고 차폐율을 측정하여 계산값과 비교하였다. 측정결과는 0.1[㎐]에서 5배 이상의 차폐율을 만족하였고, 60[㎐]에서는 86배였다. 따라서 본 논문에서 제작한 자기차폐실은 저주파 자기차폐실로 사용할 수 있을 것으로 생각된다. In this paper, the magnetically shielded room for low magnetic field shielding is designed and measured by fabricated. The size of magnetically shielded room was 3.0[m](W)×3.0[m](L)×3.0[m](H) to enter the industrial measuring instruments and analyzed DC and AC shielding characteristics of magnetic materials with a high permeability and AC shielding characteristics by eddy current of conductive materials. As a results, shielded room dimensions were obtained. To verify the analysis results, magnetically shielded room is fabricated and the calculated results are compared with the measured results. The Measured results show good agreement with calculated results. According to measurements, 5 times of 0.1[㎐] and 86 times of 60[㎐] is achieved at low frequency. The fabricated shielding room can be used as the magnetically shielding room for low magnetic field shielding.
Notch필터를 이용한 주파수 삼체배기(tripler) 설계에 관한 연구
노희정(Hee-Jung Roh),최학윤(Hak-Yun Choi) 한국조명·전기설비학회 2018 조명·전기설비학회논문지 Vol.32 No.1
Frequency multiplier is a technique for generating a high-stability, low-noise signal source in microwave and millimeter-wave communication systems, and utilizes harmonic frequencies generated by non-linearity of active elements. Depending on the harmonic output frequency to be used, it is divided into Multiplier, Tripler, and Quadrupler. In this paper, we implemented the frequency Tripler using the pHEMT device with Wide bandwidth and high conversion gain. The tripler system was designed and fabricated to obtain a 7.2GHz output signal from a 2.4GHz input signal. Measurement result 2.4 / 7.2GHz frequency tripler operates with input power of 0dBm at 2.4GHz and output power 8dBm at 7.2GHz and conversion gain up to 8dB. The implemented 7GHz band Tripler can be applied to various systems such as defense network and sensor network.
이형일(Hyeong-Il Lee),최학윤(Hak-Yun Choi) 한국컴퓨터정보학회 2011 韓國컴퓨터情報學會論文誌 Vol.16 No.6
실내나 밀폐된 축사시설에서는 청정한 환경을 유지하기 위해 온도 습도 그리고 이산화탄소, 메탄가스 등과 같은 환경요인들을 측정하고 관리하여야 한다. 이때 측정된 수치가 관리대상 구간의 정상범위 내에 존재할지라도 시설이나 축적된 배설물과 주변 환경과의 상호작용 등으로 인한 예측치 못한 상황이 발생하면 측정수치는 급격하게 증가 또는 감소하게 된다. 본 논문에서는 이처럼 급격하게 증가하거나 감소하는 비정상 패턴의 변화가 발생할 경우, 이를 인식하여 위해 요소를 미리 제거할 수 있는 조기경고기법(EWarM)을 제안하였다. 그리고 이를 기반으로 한 퍼지 에이전트를 구현하였다. 다양한 상황에서의 성능평가를 통해 조기경고기법(EWarM)에 기반한 퍼지 에이전트가 위해 요소를 제거하는데 유용하다는 것이 입증되었다. In order to maintain clean environment in an interior space and an enclosed cattle pen, we have to measure and control environmental factors which are temperature, humidity and CO2, CH4 and so on. Although the measured values are within the normal range, those are increased or decreased sharply by the feces or environmental impacts. In order to take early an appropriate action, we propose an early warning method(EWarM) in this paper, which can recognize the rapidly changing time for the increasing or decreasing rate of the measured values. In addition, we developed fuzzy control system based on an EWarM. We verified that this system based on an EWarM is used for eliminating that impacts through performance evaluation in a variety of environmental situations.