• Journal of Electrical Engineering and Technology
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• 제13권4호
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• pp.1558-1565
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• 2018

Three-phase current is reconstructed from the dc-link current in an AC machine drive with a single current sensor. Switching pattern modification methods, in which the magnitude of the effective voltage vector is secured over its minimum, are investigated to accurately reconstruct the three-phase current. However, the existing methods that modify the switching pattern cause voltage and current distortions that degrade sensorless performance. This paper proposes a variable-magnitude voltage signal injection method based on a high frequency voltage signal injection. The proposed method generates a voltage reference vector that ensures the minimum magnitude of the effective voltage vector by varying the magnitude of the injection signal. This method can realize high quality current reconstruction without switching pattern modification. The proposed method is verified by experiments in a 600W Interior permanent magnet synchronous machine (IPMSM) drive system.

• 한국콘텐츠학회논문지
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• 제15권4호
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• pp.342-349
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• 2015

본 연구는 뇌졸중 환자를 대상으로 양손 보완운동 및 한손운동을 수행하는 동안 환측의 움직임을 측정하여, 양손 보완운동의 효과를 검증하고자 수행되었다. 대상자는 부산지역에 거주하는 뇌졸중 후 편마비 환자 중 12가지 기준을 적용하여 30명을 선정하였다. 과제 수행 동안 환측의 움직임 특성을 측정하기 위해 피트메터(Fitmeter) 가속도계를 부착하여 신호벡터크기(Signal Vector Magnitude: SVM), 최고 가속도(peak acceleration), 최고 감속도(peak deceleration)를 측정하였다. 연구 결과 양손 보완운동은 한손운동보다 수행시간이 짧았고(p<0.05), 신호벡터크기가 감소하였다(p<0.05). 따라서 뇌졸중 환자가 일상생활동작을 수행할 때 환측만 사용하는 것보다 건측을 보완적으로 사용하는 것이 운동형상학적으로 움직임 향상에 도움이 될 것으로 생각된다.

• International Journal of Internet, Broadcasting and Communication
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• 제13권2호
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• pp.260-266
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• 2021

Handwriting using the dominant and nondominant arms was analyzed in 52 young adults with the aid of a three-axial accelerometer. We measured a signal vector magnitude (SVM) and the percentage of the total signal vector magnitude (%TSVM) for the metacarpophalangeal joint (MCP), radial styloid process (RSP), and lateral epicondyle (LE) of both arms. The SVM for the MCP was lower in the dominant arm than the nondominant arm, whereas that for the RSP was higher. %TVSM was lower for the MCP than for the RSP and LE in the nondominant arm, but higher for the MCP than for the LE in the nondominant arm. These findings suggest that controlling the MCP will improve the quality of handwriting, including when using the nondominant arm.

• 방송공학회논문지
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• 제20권6호
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• pp.880-887
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• 2015

본 논문은 EBME(Extended Bilateral Motion Estimation) 알고리듬에서 동일한 움직임 벡터들의 방향과 크기를 고려한 알고리듬을 제안하였다. EBME는 BME(Bilateral Motion Estimation)보다 높은 연산량을 요구하기 때문에 프레임 내의 x, y방향 각각의 평균 움직임 벡터크기를 이용하여 동적프레임과 정적프레임을 판단하고, EBME 수행여부를 판단하여 연산량을 줄인다. 또한 동일한 움직임 벡터들의 방향과 크기를 비교하여 MVS(Motion Vector Smoothing)단계 수행여부를 판단함으로써 연산량을 줄인다. 제안하는 알고리듬을 적용한 실험 결과 기존의 EBME 알고리듬에 비해 수행시간은 단축되고 PSNR(Peak Signal to Noise Ratio)은 향상 되었다.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 1998년도 하계종합학술대회논문집
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• pp.677-680
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• 1998

In this paper, we proposed a lwo bit rate subband coding with adaptive vector quantization using the correlation between motion vector and block energy in subband. In this method, the difference between the input signal and the motion compensated interframe prediction signal is decomposed into several narrow bands using quadrature mirror filter (QMF) structure. The subband signals are then quantized by adaptive vector quantizers. In the codebook generating process, each classified region closer to the block value in the same region after the classification of region by the magnitude of motion vector and the variance values of subband block. Because codebook is genrated considering energy distribution of each region classified by motion vector and variance of subband block, this technique gives a very good visual quality at low bit rate coding.

• Journal of Power Electronics
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• 제12권3호
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• pp.448-457
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• 2012

This paper proposes a carrier-based pulse width modulation (PWM) method to control an indirect matrix converter (IMC) by analyzing the relationship between the space vector PWM (SVPWM) and the carrier-based PWM. The complexity of the SVPWM method for an IMC can be reduced by using an equivalent carrier-based PWM method. The advantage of the proposed algorithm is its ability use only one symmetrical triangular carrier signal to generate the gate signals for all of the power switches in both the rectifier and inverter stages as compared to the conventional method where the carrier signal used in the rectifier stage is different from that of the inverter stage. In addition, by using a suitable offset voltage component in the modulation signals, the output voltage magnitude reaches 0.866 of the input voltage magnitude. Simulation and experimental results are provided in order to validate the proposed method.

• 재활복지공학회논문지
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• 제9권3호
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• pp.245-250
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• 2015

스마트 폰과 개인 휴대정보 단말기와 같은 장치는 일상생활에서 중요한 역할을 담당한다. 본 논문에서는 물리적 활동의 모니터링을 위해 신호벡터크기(signal vector magnitude)와 적응적인 임계값 처리에 기반한 걸음수 검출 알고리즘을 제안한다. 알고리즘은 스마트 폰에 내장된 가속도 센서와 중력 센서를 사용하여 걸음수를 측정한다. 실험결과 제안한 알고리즘이 스마트 폰의 어플에 비해 정확도와 적응성에서 좋은 성능을 나타내었다.

• Transactions on Electrical and Electronic Materials
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• 제18권6호
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• pp.320-322
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• 2017

In this paper, a high-performance, low-area gradient-magnitude calculator architecture is proposed, based on approximate image processing. To reduce the computational complexity of the gradient-magnitude calculation, vector properties, the symmetry axis, and common terms were applied in a hardware-resource-shared architec-ture. The proposed gradient-magnitude calculator was implemented using an Altera Cyclone IV FPGA (EP4CE115F29) and the Quartus II v.16 device software. It satisfied the output-data quality while reducing the logic elements by 23% and the embedded multipliers by 76%, compared with previous work.

• 융합신호처리학회논문지
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• 제16권2호
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• pp.63-68
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• 2015

본 논문에서는 신호의 파워에 따라 적응적 스텝 사이즈를 갖는 개선된 QIM(Quantization index modulation)과 SVM(Support vector machine) 디코딩 모델을 이용한 다중 오디오 워터마킹 알고리즘을 제안한다. 워터마크는 주파수 크기 응답과 주파수 위상 응답에 QIM을 이용하여 삽입한다. 이는 주파수 크기 응답과 위상 응답에 강인한 공격이 다르기 때문에 양쪽 모두 삽입하여 강인성을 보완하기 위해서이다. 검출시에는 SVM 디코딩 모델을 사용하여 검출된 워터마크가 워터마크로서의 기능이 애매모호한 경우를 개선하여 검출 비율을 향상시킨다. 강인성 검증을 위해 11개의 공격을 사용하였고 그 결과 SVM 디코딩 모델을 사용하지 않은 기존의 다중 오디오 워터마킹 방법보다 훨씬 우수한 성능을 보였다. 특히 PSNR은 최대 7dB의 개선 효과를, BER은 10%의 개선 효과를 보인 것은 주목할 만한 결과이다.

• 센서학회지
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• 제20권2호
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• pp.137-144
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• 2011

Wireless sensor network(WSN) has the potential to greatly effect many aspects of u-healthcare. By outfitting the potential with WSN, wearable sensor node can collects real-time data on physiological status and transmits through base station to server PC. However, there is a significant gap between WSN and healthcare. WSN has the limited resource about computing capability and data transmission according to bio-sensor sampling rates and channels to apply healthcare system. If a wearable node transmits ECG and accelerometer data of 4 channel sampled at 100 Hz, these data may occur high loss packets for transmitting human activity and ECG to server PC. Therefore current wearable sensor nodes have to solve above mentioned problems to be suited for u-healthcare system. Most WSN based activity and ECG monitoring system have been implemented some algorithms which are applied for signal vector magnitude(SVM) algorithm and ECG noise algorithm in server PC. In this paper, A wearable sensor node using integrated ECG and 3-axial accelerometer based on wireless sensor network is designed and developed. It can form multi-hop network with relay nodes to extend network range in WSN. Our wearable nodes can transmit 1-channel activity data processed activity classification data vector using SVM algorithm to 3-channel accelerometer data. ECG signals are contaminated with high frequency noise such as power line interference and muscle artifact. Our wearable sensor nodes can remove high frequency noise to clear original ECG signal for healthcare monitoring.