• 한국마린엔지니어링학회:학술대회논문집
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• 한국마린엔지니어링학회 2006년도 전기학술대회논문집
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• pp.109-110
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• 2006

The performance of a digital baseband signal processing and data transmission rate depends on the modulation technique. In this paper, We implemented DSP communication system for Underwater acoustic communication using by adaptive BPSK modem technique. In order to implement adaptive modem, we suggested SNR detection block. SNR detection block has the reference SNR value that selects between window filter path and matched filter path. In this paper, suggested system is based on software interface and all Hardware(PLL, modem filter, equalizer etc) is implemented by software, exclusive of DSP, A/D, D/A converter, SDRAM and Flash memory.

• 한국초전도저온공학회:학술대회논문집
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• 한국초전도저온공학회 2002년도 학술대회 논문집
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• pp.358-361
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• 2002

The millirneterwave high-T$_{c}$ superconducting(HTS) down-converter sub-system with the HTS/III-V integrated mixer as the central device is demonstrated first. The constituent components of HTS down-converter sub-system such as a single balanced type integrated mixer with rat-race coupler, a cavity type bandpass filter (26 GHz), and a HTS planar lowpass filter(1 GHz), semiconductor LNA and IF-power amplifier, a driving electronic module for A/D converter, and a Stirling type mini-cooler module were combined into an International stand- and rack of 19-inch. From the RF(-61 dBm, 26.5GHz)and LO signal(-1 dBm, 25.6 GHz), IF signal(0dBm, 0.9 GHz) agreed with simulated results is obtained.d.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2003년도 춘계학술대회논문집
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• pp.645-651
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• 2003

The system in which a microphone and a loudspeaker are simultaneously used can cause an echo. The echo is caused by feedback between the output of the loudspeaker and the input of the microphone. The acoustic echo canceller is a device to cancel the echo in a communication system. Its general procedure for cancellation is first estimating the plant response of the feedback path and then eliminating the feedback signal from the input signal. In this paper, full-band and sub-band approaches are compared by using some simulation examples.

• 한국해양공학회지
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• 제24권1호
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• pp.166-171
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• 2010

In this paper, the front-end of a digital receiver with a 25 kHz carrier frequency, 5 kHz symbol rate, and any excess-bandwidth is designed using two basic facts. The first is known as the uniform sampling theorem, which states that the sampled sequence might not suffer from aliasing even if its sampling rate is lower than the Nyquist sampling rate if the analog signal is a bandpass one. The other fact is that if the sampling rate is 4 times the center frequency of the sampled sequence, the front-end processing complexity can be dramatically reduced due to the half of the sampled sequence to be multiplied by zero in the demixing process. Furthermore, the designed front-end is simplified by introducing sub-filters and sub-sampling sequences. The designed front-end is composed of an A/D converter, which takes samples of a bandpass filtered signal at a 20 kHz rate; a serial-to-parallel converter, which converts a sampled bandpass sequence to 4 parallel sub-sample sequences; 4 sub-filter blocks, which act as a frequency shifter and lowpass filter for a complex sequence; 4 synchronized switches; and 2 adders. The designed front-end dramatically reduces the computational complexity by more than 50% for frequency shifting and lowpass filtering operations since a conventional front-end requires a frequency shifting and two lowpass filtering operations to get one lowpass complex sample, while the proposed front-end requires only four filtering operation to get four lowpass complex samples, which is equivalent to one filtering operation for one sample.

• 공업화학
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• 제16권6호
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• pp.772-777
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• 2005

본 연구에서는 발포법 및 겔-캐스팅법을 이용하여 소석회와 석회석을 원료로 다공성 필터의 제조를 제조하였다. 제조된 필터의 물성과 $SO_2$ 제거성능을 평가한 결과 다공성 석회질 필터의 기공률 및 기공크기가 클수록 수많은 윈도우에 의해서 대부분의 기공이 열린 기공으로 형성됨을 알 수 있었다. $SO_2$ 제거에 대한 다공성 석회질 필터의 영향은 다음과 같이 관찰되었다. 반응온도가 증가할수록 $SO_2$ 제거효율은 증가하였다. $SO_2$ 유입농도에 따른 제거 효율의 차이가 많이 나지 않았지만 유량 차이에 의한 효율 변화는 상대적으로 크게 나타났다. 필터의 경우 기공률이 클수록 $SO_2$ 제거효율은 우수하였으며, 기공률이 동일한 경우에서는 소석회 필터는 석회석 필터보다 $SO_2$ 제거효율이 우수하였다. 이것은 소석회의 CaO 전환율이 석회석에 비해 우수하여 $SO_2$에 의해 상대적으로 쉽게 $CaSO_4$로 형성되었기 때문으로 판단된다.

• 한국정보통신학회논문지
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• 제8권3호
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• pp.517-522
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• 2004

본 논문에서는 마이크로웨이브 채널 환경에서 대역제한필터(BL-PSF)를 이용하는 OFDM/QPSK-DMR 시스템의 성능개선에 관한 연구를 수행하였다. 성능개선을 위해 단일적응등화기(one-tap adaptive equalizer)를 OFDM/QPSK-DMR 시스템에 적용하였으며, 단일 반송파방식의 DMR 시스템과 BER 및 특성 곡선(signature curve) 성능을 비교분석하였다. 시뮬레이션 결과 마이크로웨이브 채널 환경에서 OFDM/QPSK-DMR 시스템에 단일적응등화기를 적용한 경우, 부 반송파의 수가 16일때 단일 반송파방식의 DMR 시스템보다 2 dB 이상의 페이드 마진을 갖는다. 그리고 OFDM/QPSK-DMR 시스템의 부 반송파의 수가 많을수록 페이드 마진이 더욱 증가하여 성능이 향상 되는 것을 알 수 있었다.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2000년도 봄 학술발표회논문집
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• pp.365-370
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• 2000

A sliding mode fuzzy control (SMFC) algorithm is applied to design a controller for a benchmark problem on a wind- excited building. The structure is a 76-story concrete office tower with a height of 306 meters, hence the wind resistance characteristics are very important for the serviceability as well as the safety. A control system with an active tuned mass damper is assumed to be installed on the top floor. Since the structural acceleration is measured only at ,limited number of locations without measurement of the wind force, the structure of the conventional continuous sliding mode control may have the feed-back loop only. So, an adaptive least mean squares (LMS) filter is employed in the SMFC algorithm to generate a fictitious feed-forward loop. The adaptive LMS filter is designed based on the information of the stochastic characteristics of the wind velocity along the structure. A numerical study is carried out. and the performance of the present SMFC with the ,adaptive LMS filter is investigated in comparison with those of' other control, of algorithms such as linear quadratic Gaussian control, frequency domain optimal control, quadratic stability control, continuous sliding mode control, and H/sub ∞///sub μ/, control, which were reported by other researchers. The effectiveness of the adaptive LMS filter is also examined. The results indicate that the present algorithm is very efficient .

• 전기학회논문지
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• 제66권8호
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• pp.1250-1256
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• 2017

In this research, a high-performance ultrasonic positioning system is proposed to track the positions of an indoor mobile object. Composed of an ultrasonic sender (mobile object) and a receiver (anchor), the system employs three ultrasonic time-off-flights (TOFs) and trilateration to estimate the positions of the object with an accuracy of sub-centimeter. On the other hand, because ultrasonic waves are interfered by temperature, wind and various obstacles obstructing the propagation while propagating in air, ultrasonic pulse debounce technique and Kalman filter were applied to TOF and position calculation, respectively, to compensate for the interference and to obtain more accurate moving object position. To perform tasks in real time, ultrasonic signals are processed full-digitally with a Zynq SoC, and as a software design tool, Vivado IDE(integrated design environment) is used to design the whole signal processing system in hierarchical block diagrams. And, a hardware/software co-design is implemented, where the digital circuit portion is designed in the Zynq's fpga and the software portion is c-coded in the Zynq's processors by using the baremetal multiprocessing scheme in which the c-codes are distributed to dual-core processors, cpu0 and cpu1. To verify the usefulness of the proposed system, experiments were performed and the results were analyzed, and it was confirmed that the moving object could be tracked with accuracy of sub-cm.

• 한국인터넷방송통신학회논문지
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• 제16권3호
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• pp.97-102
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• 2016

UFMC(Universal Filtered Multi-Carrier)는 최근 5G통신 시스템의 전송방식 후보로 주목 받고 있는 다중 반송파 송신기술 중의 하나이다. UFMC는 OFDM(Orthogonal Frequency Division Multiplex)의 단순함과 FBMC(Filter Bank Multi-Carrier)의 장점을 합쳐놓은 방식으로 볼 수 있다. CFO(Carrier Frequency Offset)는 다중 반송파 전송방식에서 부 반송파간의 불일치를 일으켜 BER 성능을 낮게 하는 문제점으로 작용하고 있다. UFMC에서의 CFO영향은 OFDM 보다는 크지 않지만 여전히 부 밴드간의 간섭을 일으켜 시스템 성능을 열화 시키고 있다. 이 논문에서는 UFMC에서 CFO의 변화와 EsNo값에 따른 SNR 열화를 분석 하였다.

• 한국정보전자통신기술학회논문지
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• 제10권5호
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• pp.435-441
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• 2017

중간고조파는 주파수가 기본주파수의 정수배가 아니며 크기가 고조파에 비해 작으므로 중간고조파의 정확한 검출은 쉽지 않다. 본 논문에서는 필터뱅크 시스템과 적응 예측기를 이용하는 중간 고조파 검출 기법을 제안한다. 필터 뱅크 시스템에서는 입력신호를 부밴드로 분해한다. 적응 예측기에서는 분해된 부밴드 신호를 입력신호로, 오차신호를 출력으로 하여 중간고조파를 검출한다. 이럴 경우 적응예측기의 입출력 특성이 노치필터특성을 가지므로, 예측된 고조파신호가 오차신호에서 제거되므로 중간고조파 검출이 가능하다. 검출된 중간고조파의 크기와 주파수는 순환기법을 이용하여 추정한다. 제안 기법의 성능은 고조파와 중간고조파를 정현모델로 합성한 신호를 입력으로 사용하고, 시뮬레이션을 통해 중간고조파 검출결과를 평가한다. 그리고 중간고조파 검출 결과를 MUSIC, ESPRIT와 비교하여 제안기법의 타당성을 입증한다.