• 전자공학회논문지A
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• 제33A권10호
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• pp.81-89
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• 1996

In this paper, a very efficient CAD algorithm is proposedd where rhodes formulae combined with distributed lowpass prototype filter in order to design the corrugated waveguide harmonic rejection filters accurately. The proposed algorithm resolves effectively the problem of proximity effect without any optimiation or iterative design process by using the internally convexed corrugated structure. A 13-section tapered corrugated lowpass filter has been designed by the proposed algorithm and fabricated. The experimental results are in good agreement with the calculated results.

• 전력전자학회:학술대회논문집
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• 전력전자학회 1998년도 Proceedings ICPE 98 1998 International Conference on Power Electronics
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• pp.258-263
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• 1998

A comparative study of single-phase PWM converters having active filtering functions both on ac-input and dc-output sides have been carried out. Based on the function of the dc-output side active filter, two types of configurations, the RPM (ripple power managing) type and the APM (average power managing) type are compared to show their contrastive characteristics. The prototype system using DSP based control algorithms, i.e. deadbeet current control and voltage sensor-less technique using full-order observer, show the availability of the proposed system.

• Journal of Power Electronics
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• 제11권4호
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• pp.507-511
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• 2011

This paper presents a single-switch buck converter with a ripple-free inductor current. In the proposed converter, the filter inductor current ripple is completely removed by utilizing an auxiliary circuit consisting of an additional winding of the filter inductor, an auxiliary inductor, and an auxiliary capacitor. Moreover, the ripple-free current characteristic is maintained under both light load and full load conditions. The theoretical analysis and performance of the proposed converter were verified with a 110W experimental prototype operating at a 107 kHz switching frequency.

• Journal of Power Electronics
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• 제11권5호
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• pp.662-668
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• 2011

This paper presents an analysis of a 4th order LCLC resonant converter with a capacitive output filter using the state-space approach. The analysis of the converter shows that there are four intervals in a half period. In each interval, the state-space equations are obtained. Due to the soft switching of the converter, an exact equation for the Zero Voltage Switching (ZVS) time and the maximum dead time of the inverter switches are presented. The simulation and experimental results obtained from a 10kv, 370w prototype confirm the validity of the theoretical analysis.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 추계학술대회 논문집 학회본부A
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• pp.128-130
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• 1998

A simplified control method for the single-phase active power f1Iter is proposed. This method has the advantages of using only one current sensor, a simple control circuit and low implementation cost. A model of this method is derived. A prototype is also developed to demonstrate the performance of this method. The test results show that the proposed active power filter has the expected performance.

• 한국전자파학회논문지
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• 제18권11호
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• pp.1318-1326
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• 2007

본 논문에서는 waffle-iron 도파관 여파기의 실용적인 설계 방법을 기술하였다. 설계 과정은 두 단계로 이루어진다. 첫 단계로는 waffle-iron 구조의 단일 window에 대해 EM S/W tool를 이용하여 S-파라미터를 구하고, ABCD 파라미터로 변환하여 K-인버터를 계산하고, 두 번째 단계는 분포 정수 원형 여파기와 일치되게 window의 크기를 최적화한다. 설계 방법을 검증하기 위해 위성통신용 Ka 대역 여파기를 설계하고 제작하였다. 측정 결과는 계산 결과와 비교하여 양호하게 일치하였다.

• 한국컴퓨터정보학회논문지
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• 제3권3호
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• pp.107-112
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• 1998

본 논문에서는 마이크로스트립 선로로 제작이 쉽고, 스터브를 사용한 필터보다 적은 공간을 차지하는 Hi-Z, Low-Z 필터를 사용하여 마이크로스트립 필터를 설계.제작하였다. 이 필터는 선로의 전기적 길이가 매우 짧은 경우. 즉 Bl＜$\pi$/4의 조건에서, 저역통과기본형의 직렬 인덕터일 때 고 임피던스 선로부로 병렬 커패시터를 저 임피던스 선로부로 대치할 수 있다. 이렇게 대치된 각 단을 마이크로스트립 선로로 설계하기 위해 주어진 마이크로스트립의 실효 유전율을 구해서 각 단의 폭과 길이를 계산하고 필터 설계에 사용하였다. 또한, 설계된 필터를 Touchstone의 이론치와 제작된 필터의 실험치를 비교하여 응답특성을 분석하였다.

• 한국전자파학회논문지
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• 제16권4호
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• pp.438-446
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• 2005

본 논문에서 변형된 generalized Chebyshev 유리함수가 제시되었다. 이 함수를 이용한 회로망 합성으로 새로운 원형 저역 통과 필터의 소자값이 구해졌다. 이 제안된 필터는 기존의 generalized Chebyshev 필터와 마찬가지로 통과 대역에서 등리플을 갖지만 유한 주파수에서 오직 하나의 감쇠극을 갖는 기존의 필터와는 달리, 제안된 필터는 저지 대역에서 서로 다른 두 개의 감쇠극을 갖는다. 만약 고조파가 두 번째 감쇠극 주파수에 맞춰진다면, 고조파를 효과적으로 억제할 수 있다. 게다가, 두 번째 감쇠극의 위치는 임의로 조정될 수 있기 때문에 제안한 필터는 넓은 저지 대역 구현에 특히 유용하다.

• 한국산업융합학회 논문집
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• 제24권5호
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• pp.581-587
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• 2021

In recent years, contamination of drinking water sources has emerged as a serious social problem, such as a large number of impurities in tap water or groundwater or the supply of suitable water due to rust of pipes. Although the government and public institutions are implementing various measures to protect water sources, they cannot improve water quality in a short period of time because of the enormous cost involved. Therefore, in recent years, preference has been given to a device that converts tap water, which is hard water, into soft water by installing a separate water softener at the faucet from which tap water is discharged. However, the existing filtration device has a problem that filtration performance is gradually lowered when impurities accumulate in the filter, requiring continuous filter replacement. In this study, the optimal design of the filter housing was performed to develop a water softener that can be washed when impurities accumulate on the filter inside the water softener connected to the faucet. For optimal design of the filter housing, fluid and fluid-structural interaction analysis were performed on the design pressure to determine the shape and thickness of the housing, and design review was performed through prototype.

• Journal of Power Electronics
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• 제19권1호
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• pp.44-57
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• 2019

Recently, the use of LLCL filters for grid inverters has been suggested to give better harmonic attenuation than the commonly used L and LCL filters, particularly around the switching frequency. Nevertheless, this filter is mainly designed for constant switching frequency pulse width modulation (CSF PWM) methods. In variable switching frequency PWM (VSF PWM), the harmonic components are distributed across a wide frequency band which complicates the use of a high order filter, including LCL and LLCL filters. Recently, a confined band variable switching frequency (CB-VSF) PWM method has been proposed and demonstrated to be superior to the conventional constant switching frequency (CSF) PWM in terms of switching losses. However, the applicability of LLCL filters for this type of CB-VSF PWM has not been discussed. In this paper, the authors study the suitability of an LLCL filter for CB-VSF PWM and propose design guidelines for the filter parameters. Using simulation and experimental results, it is demonstrated that the effectiveness of an LLCL filter with CB-VSF PWM depends on the parameters of the filters as well as the designed variable frequency band of the PWM. Simulation results confirm the performance of the suggested LLCL design, which is further validated using a lab scale prototype.