• 대한전기학회:학술대회논문집
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• 대한전기학회 2015년도 제46회 하계학술대회
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• pp.133-134
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• 2015

최근 전자기술이 발달함에 따라, 전자기기의 집적도가 높아지고 있으며, 그에 따라 전자기적 간섭(Electromagnetic Interference)이 큰 문제로 대두되고 있다. 특히, 집적도가 높은 스마트 기기(Smart Device)의 AP(Applicaton Processor)의 경우, 여러 기능을 수행하는 부품이 집적된 SOC(System On Chip)이기 때문에, 전자기적 간섭에 더 민감할 수 있다. 더불어 LTE(Long Term Evolution)을 무선통신으로 이용하는 다양한 주파수대에서 전자기적 간섭은 어플리케이션 및 전자기기의 오작동을 초래할 수 있다. 이를 해결하기 위하여 본 논문에서는 칩패캐지 레벨의 Meander 구조의 기존 필터(Filter)가 가진 문제점을 해결한 구조를 설계하여 3차원 상의 전자장 시뮬레이션을 수행하였다. 또한, 칩의 내성(Immunity)이 취약한 여러 주파수 범위를 차단할 수 있는 이 중 대역차단 필터(Dual Band Stop Filter)를 Meader Line구조를 단순하게 만들어 설계하고 그에 따른 결과를 분석하였다.

• 한국정보보호학회:학술대회논문집
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• 한국정보보호학회 2001년도 종합학술발표회논문집
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• pp.464-468
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• 2001

In this paper, we propose a robust watermarking technique that accepts time scaling, pitch shift, add noise and a lot of lossy compression such as MP3, AAC, WMA. The technique is developed based on digital filtering. Being designed according to critical band of HAS (human auditory system), the digital filters nearly affect audio quality. Furthermore, before implementing digital filtering, wavelet transform decomposes the audio signal into several signals that is composed of specific frequencies. Designed digital filters scan the decomposed signal. The designed digital filter, band-stop filter, distorts and eliminates specific frequencies of audio signals. Watermarking detection can be accomplished by FFT (Fast Fourier Transform). Firstly, segments of audio signal are transformed by FFT. Then, the obtained amplitude spectrum by FFT is summed repeatedly. Finally the watermark detector can find filters used to watermark encoding based on eliminating frequencies. The suggested technique can embed 4bits/s in a robust manner.

• 한국정보통신설비학회:학술대회논문집
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• 한국정보통신설비학회 2006년도 하계학술대회
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• pp.208-211
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• 2006

In this paper, a tunable image rejection filter using two varactors is developed for mobile convergence. The filter is fabricated on a 0.25um substrate. ESD Pad is embedded to prevent damage caused by electrostatic discharge(ESD). Bias voltages are at WCDMA(2.1GHz). WiBro(2.3GHz), and WLAN(2.45) are 0.5V, 0.95V and 1.8V respectively. And the image rejection rations are more than 28dB at each band and insertion losses are less than 2dB at each band.

• Journal of the Optical Society of Korea
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• 제15권2호
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• pp.202-206
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• 2011

We propose a tunable flat-top bandpass filter to pass light in a customized wavelength band by using long-period fiber gratings (LPFG) structure. The LPFG structure is composed of a core mode blocker in between two LPFGs. The bandpass spectrum of the proposed structure is obtained in overlapped wavelength band of two LPFGs operating on the same modes. To analyze the properties, we introduce a mathematical matrix model for the structure. We theoretically demonstrate flexibility of the flat-top bandpass filter with various bandwidths.

• ETRI Journal
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• 제32권1호
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• pp.148-150
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• 2010

This letter presents the design of a compact bandstop filter (BSF) operating at two frequencies. The proposed BSF consists of open-ended stepped impedance resonators (OSIR) and an end-shorted parallel-coupled microstrip line (E-PCML). The OSIRs are used to achieve the impedance-controlled stopband positions. The wide BSF bandwidths are achieved through enhanced coupling of the E-PCML. Explicit design guidelines are derived using a lossless transmission line model. To validate theoretical predictions, a prototype dual-band BSF operating at 900 MHz and 2,100 MHz with fractional bandwidths of 72% and 36%, respectively, is implemented in microstrip.

• 한국전자파학회논문지
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• 제11권1호
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• pp.76-83
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• 2000

본 논문에서는 세라믹 동축 공진기와 Varactor Diode를 이용하여 800MHz~900MHz에서 2단 가변 대역통과 여파기를 설계 제작하였다. ABCD Parameter를 이용하여 $\pi$형 Inverter를 T형 등가회로로 변환하여 Varactor Diode 수를 2개로 최적화하였다. 가변대역은 800MHz~900MHz이며 삽입손실을 $405dB\pm0.5dB$ 이내 반사손실은 15dB 이상으로 설계하였다. 제작된 대역통과 여파기는 Simulation 결과와 잘 일치하였다.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2003년도 통신소사이어티 추계학술대회논문집
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• pp.317-322
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• 2003

In this paper, we design a slow-wave bandpass filter that uses a microstrip line periodically loaded with microstrip ing resonators for WLAN(5 GHz). Unlike conventional slow-wave filters, this filter is designed to produce a narrow passband at the fundamental mode of the resonators and provide lower insertion loss than that of parallel- or cross-coupled ring bandpass filters. A PBG(Photonic Band Gap) structure patterned in the ground plane is used to suppress the spurious transmission and extend out-of-band rejections Experimental result shows that the first spurious response in the stopband of the slow-wave bandpass filter can be rejected using a PBG structure.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2001년도 추계학술대회논문집 II
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• pp.1104-1108
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• 2001

It is a difficult and important task to measure the reverberation time of an acoustic room with a short reverberation time. This paper presents a new technique to measure the reverberation time of an acoustic room with low value of BT60. The digital signal processing technique used to do this is the wavelet filter which is very flexible to design the 1/n octave band filter and has no delay problem compared with the conventional IIR digital filter. This method is successfully applied to the measurement of the reverberation time at low frequency band of famous concert halls in Korea.

• Journal of Electrical Engineering and information Science
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• 제1권1호
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• pp.70-76
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• 1996

In this paper, we have proposed a band stop filter (BSF) for pre-processing of image sequences before encoding. By pixel-wise temporal filtering of the image sequences using the BSF, the bandwidth and noise of the signal are reduced, while preserving the image quality in view of human visual perceptions. As a result, when compared to the original image sequences, te pre-filtered image sequence requires lower bit-rates for encoding, while there is not much degradation in quality. Also, it has been shown that the proposed BSF causes less smearing and blurring than the conventional recursive low pass filter for bandwidth and noise reductions.

• ETRI Journal
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• 제25권5호
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• pp.345-355
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• 2003

In this paper, we propose a method for designing a class of M-channel, causal, stable, perfect reconstruction, infinite impulse response (IIR), and parallel uniform discrete Fourier transform (DFT) filter banks. It is based on a previously proposed structure by Martinez et al. [1] for IIR digital filter design for sampling rate reduction. The proposed filter bank has a modular structure and is therefore very well suited for VLSI implementation. Moreover, the current structure is more efficient in terms of computational complexity than the most general IIR DFT filter bank, and this results in a reduced computational complexity by more than 50% in both the critically sampled and oversampled cases. In the polyphase oversampled DFT filter bank case, we get flexible stop-band attenuation, which is also taken care of in the proposed algorithm.