• ETRI Journal
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• 제26권6호
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• pp.555-559
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• 2004

We propose an efficient digital IF down converter architecture for dual-mode WCDMA/cdma2000 based on the concept of software defined radio. Multi-rate digital filters and fractional frequency conversion techniques are adopted to implement the front end of a dual-mode receiver for WCDMA and cdma2000. A sub-sampled digital IF stage was proposed to support both WCDMA and cdma2000 while lowering the sampling frequency. Use of a CIC filter and ISOP filter combined with proper arrangement of multi-rate filters and common filter blocks resulted in optimized hardware implementation of the front end block in 292k logic gates.

• 대한의용생체공학회:의공학회지
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• 제10권3호
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• pp.293-302
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• 1989

A Dual Sensor Wiener Filter technique was used to improve the image quality of the scanning type digital radiographic system (resolution and SNR). In this method, two images were acquried simultaneously using two sensors with high and low resolution and SNR values. Using the cross Power spectrum between dual sensor outputs of the same chest radiographic image. we design a new type of Wiener Filter and implement it with fast algorithm. We compared the performance of this new dual sensor filter with conventional single sensor filters (Wiener Filter and Parametric Projec- tion Filter) . In simulation studies, it is shown that this new method has SNR improvement of 1-3 dB better than conventional filters.

• 전자공학회논문지D
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• 제34D권10호
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• pp.53-59
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• 1997

In this paper, we present a 20 GHz low-loss dual-mode channel filter designed by using mode matching method. The performance of dual-mode channel filter mainly depends on iris characteristics. Therefore the exact design of iris is the key point to get good frequncy response of the filter. MOde matching technique is widely used ot design several kinds of waveguide filters because it is simple in theory and can easily calculate the scattering matrices at the discontinuities with simple structure like iris coupled filters. Additionally the effect for finite thickness of the iris in the dual-mode cavity iflter is analyzed by te full-wave method, providing the exact filter implementation without trial and error.

• Journal of electromagnetic engineering and science
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• 제11권3호
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• pp.186-191
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• 2011

This paper presents a simple and effective method for improving stopband rejection characteristics of previously studied dual-band filters. Small electric couplings were applied to the symmetrically positioned shunt resonators, which divided each transmission zero into two transmission zeros without any effect on passbands. We were able to achieve improved stopband rejection characteristics by these additional transmission zeros. For the filter application, we designed a dual-band filter with improved stopband characteristics using microstrip quasi-lumped elements. The electric couplings that control the location of transmission zeros are controlled by the distance between symmetric open stubs of the filter. The filter was fabricated with a relative dielectric constant of 3.5 and a thickness of 0.76 mm. The fabricated filter has a small size ($14.6{\times}13.2{\times}0.76$ mm) and a low insertion loss when compared with conventional filters.

• 한국전자파학회논문지
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• 제15권3호
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• pp.301-310
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• 2004

본 논문에서는 마이크로스트립 공진기에 엇갈린 슬롯과 한 쌍의 spur-line을 삽입한 소형 이중모드(dual-mode)여파기를 제안하였다. 제안한 여파기는 급전선과 공진기 사이에 존재하는 급전 갭(coupling gap)을 없앰으로써 삽입손실의 특성이 향상되었다. 엇갈린 슬롯만 가진 기존의 이중모드 여파기와 비교할 때, 엇갈린 슬롯과 spur-line을 동시에 갖는 이중모드 여파기는 이중모드 특성을 나타내는 섭동의 범위가 상당히 넓기 때문에 이중 모드 여파기의 설계가 용이해졌다. 또한, 제안된 구조의 가장자리에 존재하는 spur-line에 2개의 PIN다이오드를 삽입하여 개폐기 특성을 갖는 여파기로의 응용도 가능하였다. 또한 제안한 구조는 공진기에 삽입된 슬롯과 spur-line에 의해 전기적인 길이가 길어지므로 기존의 구조에 비해 34.7 %의 크기 감소 효과를 얻을 수 있었다.

• ETRI Journal
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• 제30권2호
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• pp.268-274
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• 2008

This paper proposes an open-loop clock recovery circuit (CRC) using two high-Q dielectric resonator (DR) filters for 39.8 Gb/s and 42.8 Gb/s dual-mode operation. The DR filters are fabricated to obtain high Q-values of approximately 950 at the 40 GHz band and to suppress spurious resonant modes up to 45 GHz. The CRC is implemented in a compact module by integrating the DR filters with other circuits in the CRC. The peak-to-peak and RMS jitter values of the clock signals recovered from 39.8 Gb/s and 42.8 Gb/s pseudo-random binary sequence (PRBS) data with a word length of $2^{31}-1$ are less than 2.0 ps and 0.3 ps, respectively. The peak-to-peak amplitudes of the recovered clocks are quite stable and within the range of 2.5 V to 2.7 V, even when the input data signals vary from 150 mV to 500 mV. Error-free operation of the 40 Gb/s-class optical receiver with the dual-mode CRC is confirmed at both 39.8 Gb/s and 42.8 Gb/s data rates.

• 한국통신학회논문지
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• 제28권7A호
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• pp.557-562
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• 2003

An output multiplexer of manifold type is widely used in a recent satellite transponder for its mass and volume reduction. For correct operation, the filters of such a multiplexer must be singly terminated. In this paper, a simple synthesis method of a 6-pole dual-mode singly-terminated filter is described. From the transfer function of the filter, network parameters such as in/output terminations and coupling coefficients are obtained easily without complicated matrix algebra such as orthogonal projection and similarity transformation. Two different-structure filters are taken into consideration and the network parameters of each filter have been extracted from the same transfer function. It is shown that the responses of two filters are same to each other since their network parameters are obtained from the same transfer function. The method described in this paper can be applied to the other degree singly terminated filter.

• Journal of electromagnetic engineering and science
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• 제13권2호
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• pp.93-103
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• 2013

This paper presented a novel approach for the design of a tunable dual-band bandpass filter (BPF) with independently tunable passband center frequencies and bandwidths. The newly proposed dual-band filter principally comprised two dual-mode single band filters using common input/output lines. Each single BPF was realized using a varactor-loaded transmission line resonator. To suppress the harmonics over a broad bandwidth, a defected ground structure was used at the input/output feeding lines. From the experimental results, it was found that the proposed filter exhibited the first passband center frequency tunable range from 1.48 to 1.8 GHz with a 3-dB fractional bandwidth (FBW) variation from 5.76% to 8.55%, while the second passband center's frequency tunable range was 2.40 to 2.88 GHz with a 3-dB FBW variation from 8.28% to 12.42%. The measured results of the proposed filters showed a rejection level of 19 dB up to more than 10 times the highest center frequency of the first passband.

• 대한환경공학회지
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• 제22권5호
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• pp.919-926
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• 2000

정수장 여과지 모형실험장치를 이용하여 수중입자입도분석에 의한 모래 및 이중여재 여과지에 대한 여과특성 및 효율 평가를 탁도분석과 비교하여 실시하였다. 수중입자입도분석은 여과지의 효율 평가를 위한 훌륭한 평가방법으로 탁도분석에 비해 민감도가 뛰어나 여과유출수의 탁질누출 현상을 뚜렷이 관찰할 수 있었다. 모래여과지의 경우는 여과지속시간 내내 비교적 양호한 수질을 보여, 허용수두하에서는 초기탁질누출보다는 여과말기의 수위상승에 대한 주위가 필요하다. 반면에 이중여재 여과지의 경우는 내부여과에 의한 탁질의 침투가 이루어지므로 최적운영을 위해서는 적절한 여재구성과 각 여과지별로 연속적인 수질모니터링에 의한 탁질누출제어가 요구된다. 또한 보다 안정적이고 효율적인 수질의 확보를 위해서는 여과보조제의 사용도 고려되어야 할 것이다.

• 한국항해항만학회지
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• 제32권6호
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• pp.481-487
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• 2008

선박용 무선 LNA은 설비의 용이성 원가절감, 다양한 기능성에 따라 각광 받고 있다. 본 논문에서는 무선 LAN 주파수인 2.4 GHz대역과 5 GHz대역의 이중 대역통과 필터를 사각패치를 적용한 이중모드 사각 루프 공진기를 이용하여 설계하는 방법을 제안하였다. 사각패치 형태인 한 개의 perturbation element와 세 개의 reference element의 크기를 조절하여 2.4 GHz와 5.8 GHz의 두 주파수 대역에서 만족하는 이중 대역통과 필터를 설계하였으며, 나아가서 개방 스터브를 적용시켜 서지대역을 조절하여 2.4 GHz와 5.2 GHz의 두 주파수 대역에서 만족하는 새로운 형태의 이중 대역통과 필터를 설계하는 방법을 제안하였다. 제작된 이중 대역통과 필터의 설계 결과와 측정 결과가 거의 일치하였으며, 따라서 본 논문이 제안한 설계 방법이 타당함을 확인하였다.