• 대한의용생체공학회:학술대회논문집
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• 대한의용생체공학회 1996년도 춘계학술대회
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• pp.31-35
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• 1996

This paper presents a real time algorithm for monitoring of the arrythmia of ECG signal. A real time monitoring, following by detecting a QRS complex, is the most important. Using 2-dimensional time-delay coordinates which are reconstructed by the phase portrait plotting special trajectory, we detect QRS complexes. In this study, arrythmias are detected by matching the past standard template with tile present pattern when changing abruptly In order to matching with each other, we propose modified chain coding algorithm which applies vetor table consisting of eight orthonormal code(=binary code) to the phase portraits. This algorithm using logical function increases the weight if exceeding to the threshold determinded by correlation value and the distance from a straight line(y=x). Evaluating the performance of the proposed algorithm, we use standard MIT/BIH database. The results are fellowing, 1) Improve the speed of matching template than that of cross-correlation ever has been used. 2) Because the proposed algorithm is robust to varing fiducial point, it is possible to monitor the ECG signal with irregular RR interval. 3) In spite of baseline wandering owing to the low frequency noise, monitoring performance is not reduced.

• 융합신호처리학회논문지
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• 제7권4호
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• pp.155-160
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• 2006

본 논문에서는 웨이브릿 변환 영역의 4개의 서브밴드와 임계값 처리를 이용하는 계층적 블록 매칭 알고리즘을 제안하였다. 제안한 알고리즘은 다분해능의 첫 번째 레벨에서 웨이브릿 변환 영역의 4개 서브밴드를 이용함으로써 복원된 영상의 PSNR 성능을 향상시켰고, 움직임 벡터에 대한 임계값 처리를 하여 계산량을 줄였다. Carphone 영상과 Mother and Daughter 영상에 대한 실험에서 기존의 계층적 움직임 추정 알고리즘과 비교하여 임계값을 0으로 하였을 경우에 계산량은 최대 16%까지 증가하였으나 복원된 영상의 PSNR 성능은 최대 0.16dB 정도 향상된 결과를 보였고, 임계값을 증가시킴에 따라서 계산량은 최대 8%정도 줄고 복원된 영상의 PSNR은 비슷한 성능을 보였다.

• 한국자기학회지
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• 제5권6호
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• pp.947-951
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• 1995

페라이트는 높은 자기적 손실을 이용하여 전자파 흡수체로 사용하고 있다. 전자파 흡수체는 미세조직이 균일하고 미세할수록 흡수특성이 향상된다. 유기산염 열분해법으로 합성한 분말을 사용하여 Cu-Ni-Zn 페라이트를 제조하였다. 복소유전율과 복소투자율은 밀도가 높고, 입자의 크기가 미세할수록 상승하였다. 페라이트의 정합두께는 소결온도가 높을수록 얇아졌다. Cu-Ni-Zn 페라이트의 전자파 흡수능은 정합두께가 6.75 mm 일 때 160 MHz 부터 640 MHz 까지의 주파수에서 20dB 이상의 값이엿다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제13권5호
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• pp.2400-2413
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• 2019

Doubly-selective (DS) fading channel is often occurred in many orthogonal frequency division multiplexing (OFDM) communication systems, such as high-speed rail communication systems and underwater acoustic (UWA) wireless networks. It is challenging to provide an accurate and fast estimation over the doubly-selective channel, due to the strong Doppler shift. This paper addresses the doubly selective channel estimation problem based on complex exponential basis expansion model (CE-BEM) in OFDM systems from the perspective of distributed compressive sensing (DCS). We propose a novel DCS-based improved sparsity adaptive matching pursuit (DCS-IMSAMP) algorithm. The advantage of the proposed algorithm is that it can exploit the joint channel sparsity information using dynamic threshold, variable step size and tailoring mechanism. Simulation results show that the proposed algorithm achieves 5dB performance gain with faster operation speed, in comparison with traditional DCS-based sparsity adaptive matching pursuit (DCS-SAMP) algorithm.

• 반도체디스플레이기술학회지
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• 제22권2호
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• pp.50-55
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• 2023

Due to the unavailability of global positioning system (GPS) indoors, various indoor pedestrian positioning methods have been designed to estimate the position of the user using received signal strength (RSS) measurements from radio beacons, such as wireless fidelity (WiFi) access points and Bluetooth low energy (BLE) beacons. In indoor environments, radio-frequency (RF) signals are unpredictable and change over space and time because of multipath associated with reflection and refraction, shadow fading caused by obstacles, and interference among different devices using the same frequencies. Therefore, the outliers in the positional information obtained from the indoor positioning method based on RSS measurements occur often. For this reason, the performance of the positioning method can be degraded by the characteristics of the RF signal. To resolve this issue, a map-matching (MM) algorithm based on maximum probability (MP) estimation is applied to the indoor positioning method in this study. The MM algorithm locates the aberrant position of the user estimated by the positioning method within the limits of the adjacent pedestrian passages. Empirical experiments show that the positioning method can achieve higher positioning accuracy by leveraging the MM algorithm.

• 한국소음진동공학회논문집
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• 제23권7호
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• pp.662-668
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• 2013

In this paper, possibility of controlling motion of a floating structure using a tuned liquid damper (TLD) is numerically investigated. A TLD is a tank partially filled with liquid. Sloshing motion of liquid inside a tank is known to suppress movement of the tank subject to external excitations at specific frequency. The effects of sloshing phenomena inside a rectangular floating body on its surge motion are investigated by varying external excitation frequency. First, a grid-refinement study is carried out to ensure validity of grid independent numerical solutions using present numerical techniques. Then, surge motion of the floating body subjected to external wave is simulated for five different excitation frequencies of which the center frequency equals to the natural frequency of internal liquid sloshing. The normalized amplitudes of surge motion of the target floating body are compared according to the excitation frequency, for the cases with and without water inside the floating body. It is shown that the motion of the floating body can be minimized by matching the sloshing natural frequency to the excitation frequency.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2004년도 ICCAS
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• pp.466-469
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• 2004

In this paper, we improve the matching impedance of antennas by inserting parasitic slots on the ground plane of right-angle triangular slot antennas. The designed antennas characteristics are analyzed by using Finite Different Time Domain (FDTD) method, the specific design frequency is 10 GHz and match impedance is 50 ohms. Simulation results show that the efficient of return loss and radiation patterns are improved and enhance. In this case, the right-angle triangular slot antennas with parasitic slots have matching impedance better than antennas without parasitic slots.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제14권9호
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• pp.3680-3692
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• 2020

The purpose of this study is to orient users' touchpoints in co-design experience, to identify their need via visualized experience map, to recommend valid design information in online e-customization services. A user-centered co-design experience map (UCEM) is adopted to analyze the relation between users' desire and time spent, so as to evaluate the online co-design experiences. Based on evolutionary algorithm and fuzzy theory, data of this study is collected from 30 participants. The data was analyzed by descriptive analysis in SPSS, and frequency query and word cloud in NVivo. Employing design category and evaluating users' time spent, the findings are that (a) vamp color matching is consistent with interview data; (b) supported by qualitative feedback, the virtual experience map played an important role in the co-design process and the visualized interaction process; and (c) participants prefer to get more information and professional help on color matching and exterior design. Based on the findings in design category, future work should be focused on developing a better understanding of design resource recommendations and multi-stakeholder communication.

• 정보통신설비학회논문지
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• 제9권4호
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• pp.153-157
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• 2010

In this paper, a dual band LNA (Low Noise Amplifier) with a LC-tank matching circuit is designed for 912MHz and 2.45GHz RFID reader. The operating frequency is decided by the LC-tank resonance. The simulated results demonstrate that S21 parameter is 11.683dB and 5.748dB at 912MHz and 2.45GHz, respectively, and the S11 are -10.796dB and -21.261dB, the S22 are -7.131dB and -14.877dB at the same frequencies. The measured NF (Noise Figure) is 0.471 and 1.726 at 912MHz and 2.45GHz, respectively.

• 한국전자통신학회논문지
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• 제5권6호
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• pp.664-671
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• 2010

본 논문에서는 지그비를 이용한 이동 로봇의 자율주행의 선행 연구로서, 메시 네트워크가 가능한 Zigbee Pro 표준안을 지원하는 CC2520을 기반으로 한 지그비 모듈을 개발하였다. 제작 후 성능 개선의 방법으로 지그비 무선 주파수 대역에 맞는 안테나를 네트워크 분석기를 이용하여 선택하였다. 또한 지그비 모듈의 임피던스 매칭을 실행하여 무선 통신의 가능한 송 수신 거리를 늘렸으며, 통신의 안정성을 확보하였다.