• ETRI Journal
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• 제40권4호
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• pp.531-536
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• 2018

The weighted K-nearest neighbor (WKNN) algorithm is used to reduce positioning accuracy, as it uses a fixed number of neighbors to estimate the position. In this paper, we propose a dynamic threshold location algorithm (DH-KNN) to improve positioning accuracy. The proposed algorithm is designed based on a dynamic threshold to determine the number of neighbors and filter out singular reference points (RPs). We compare its performance with the WKNN and Enhanced K-Nearest Neighbor (EKNN) algorithms in test spaces of networks with dimensions of $20m{\times}20m$, $30m{\times}30m$, $40m{\times}40m$ and $50m{\times}50m$. Simulation results show that the maximum position accuracy of DH-KNN improves by 31.1%, and its maximum position error decreases by 23.5%. The results demonstrate that our proposed method achieves better performance than other well-known algorithms.

• 음성과학
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• 제13권3호
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• pp.7-18
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• 2006

Diagnosis of pathological voice is one of the important issues in biomedical applications of speech technology. This study focuses on the discrimination of voice disorder using HMM (Hidden Markov Model) for automatic detection between normal voice and vocal fold disorder voice. This is a non-intrusive, non-expensive and fully automated method using only a speech sample of the subject. Speech data from normal people and patients were collected. Mel-frequency filter cepstral coefficients (MFCCs) were modeled by HMM classifier. Different states (3 states, 5 states and 7 states), 3 mixtures and left to right HMMs were formed. This method gives an accuracy of 93.8% for train data and 91.7% for test data in the discrimination of normal and vocal fold disorder voice for sustained /a/.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제14권2호
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• pp.687-701
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• 2020

In the production of industrial fabric, it needs automatic real-time system to detect defects on the fabric for assuring the defect-free products flow to the market. At present, many visual-based methods are designed for detecting the fabric defects, but they usually lead to high false alarm. Base on this reason, we propose a Sobel operator combined with patch statistics (SOPS) algorithm for defects detection. First, we describe the defect detection model. mean filter is applied to preprocess the acquired image. Then, Sobel operator (SO) is applied to deal with the defect image, and we can get a coarse binary image. Finally, the binary image can be divided into many patches. For a given patch, a threshold is used to decide whether the patch is defect-free or not. Finally, a new image will be reconstructed, and we did a loop for the reconstructed image to suppress defects noise. Experiments show that the proposed SOPS algorithm is effective.

• 센서학회지
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• 제22권3호
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• pp.191-196
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• 2013

A particulate matter sensor fabricated by MEMS process is proposed. It is developed to accommodate Euro6 on-board diagnostics regulation for diesel automobile. In the regulation, emission of diesel particulate matter is restricted to 9 mg/km. Particulate matter sensor is designed to use induced charges by charged particulate matter. To increase sensitivity of the sensor, groove is formed on sensor surface because wider surface area generates more induced charges. Sensitivity of the sensor is measured 10.6 mV/(mg/km) and the sensor shows good linearity up to 15.7 mg/km. Also its minimum detectable range is about 0.25 mg/km. It is suitable to detect failure of a diesel particulate filter which should filter particulate matter more than 9 mg/km. For removing accumulated particulate matter on the sensor which can disturb normal operation, platinum heater is designed on the backside of the sensor. The developed sensor can sense very low amount of particulate matter from exhaust gas in real-time with good linearity.

• 한국해양공학회지
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• 제28권1호
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• pp.55-63
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• 2014

In this paper, we propose an threshold-based Schur algorithm for estimating the media characteristics of sub-bottom multi-layers by using the signal generated by a parametric array transducer. We use the KZK model to generate a parametric array signal, and use the proposed threshold-based Schur algorithm for estimating the reflection coefficients of multiple sea bottom layers. Using computer simulation, we verify that the difference frequency component generated by the KZK model prevails over the signals of primary frequencies at long range. For the simulation, we use the transmit signal generated by the KZK and the reflected signal obtained from a lattice filter model for the seawater and sub-bottom of multi-level non-homogeneous layers. Through the simulation, we verify that the proposed threshold-based Schur algorithm can give much more accurate and efficient estimates of the reflection coefficients than methods using received signal, matched filter output signal, and normal Schur algorithm output.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2009년도 제40회 하계학술대회
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• pp.2021_2022
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• 2009

Partial discharges(PD) is a important factor to evaluate the insulation state in high voltage electric machinery. However, measuring PD under the circumstances of power plant is occasionally impossible due to the relatively high magnitude of noise which is emanated from the operating machinery. In some case, the instrument measuring PD can not even perform a calibration that initializes tools and enhance the accuracy. This paper presents that we devised a noise reduction method and demonstrated the usefulness in acquiring reliable PD signals. We attached a series of filter and transformer at the input of power source of the instruments which refrains high noise signals from incoming to the instruments. We experimented the efficiency of noise reduction applying the device into the Dangjin Power Plant and Factory. As a result of testing with the filter and transformer, we can easily calibrate the PD signal compared to the case without the device. Additionally, we can detect the small PD signal which was unperceived with a normal device.

• 한국방송∙미디어공학회:학술대회논문집
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• 한국방송공학회 2015년도 하계학술대회
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• pp.464-465
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• 2015

본 논문은 HEVC(High Efficiency Video Coding) 기반의 3차원 비디오 부호기에서 깊이 비디오 부호화의 효율 증대를 위한 디블록킹 필터(deblocking filter)를 제안한다. 디블록킹 필터는 블록 왜곡(blocking artifact)을 보정하기 위한 필터인데 원래 색상 영상의 특성에 맞게 설계되어서 비슷한 목적을 지닌 SAO(Sample Adaptive Offset)와 더불어 기존 방법의 깊이 비디오 부호화에서는 사용되지 않는다. 제안 방법은 디블록킹 필터의 사전 실험 통계에 기반하여 기여도가 낮은 normal 필터를 제외시킨다. 또한, 깊이 비디오의 특성을 고려하여 임펄스 응답(impulse response)를 변형하였다. 이 변형된 디블록킹 필터를 깊이 비디오 부호화에만 적용하고 색상 비디오 부호화에는 기존 디블록킹 필터를 사용하였다. 3D-HTM(HEVC Test Model) 13.0 참조 소프트웨어에 구현하여 실험한 결과, 기존 방법에 비해 깊이 비디오 부호화 성능이 5.2% 향상되었다. 색상-깊이 비디오 간 참조가 있기 때문에 변형된 깊이 비디오 부호화가 색상 비디오 부호화 효율에 영향을 끼칠 수도 있지만 실험 결과 색상 비디오 부호화 성능은 유지되었다. 따라서 제안 방법은 성공적으로 깊이 비디오 부호화의 효율을 증대시켰다.

• 한국전자통신학회논문지
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• 제10권3호
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• pp.349-356
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• 2015

광학적 잡음과 전기적 잡음을 복합적으로 제거할 수 있는 하이브리드 필터를 채용하고 펄스형태의 아크 광 신호를 적분하여 수신되는 아크에너지의 크기로 감지할 수 있는 원격감시 기능을 갖는 고감도 부분방전 센서를 구현하였다. 하이브리드 필터는 부분방전 센서가 설치되는 배전반 내 환경에서 내부 형광등과 백열등 조명에 대하여 영향을 받지 않음을 보여주었다. 종래에는 아크광의 불규칙한 파형특성으로 인하여 첨두치가 감지되어 아크광의 크기에 비례한 선택적 감지가 어려웠으나, 센서에 적용된 적분연산 기능은 각기 다른 아크광의 에너지 레벨에 대하여도 선택적으로 감지가 가능함을 실험적으로 보여주었다. 센서는 2m 이격된 원격지에서 100A 저압 MCCB의 정상 개폐 시 발생하는 섬광에 해당하는 광 에너지에 대해서도 감지가 가능함을 보여주어 원격감시 기능을 갖는 고감도 부분방전센서에 적용 가능함을 보여주었다.

• 전력전자학회논문지
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• 제14권2호
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• pp.134-141
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• 2009

전원사고로 인하여 야기되는 전원급변상황에서 위상각의 새로운 PLL 방법은 추종속도를 개선시키기 위하여 제안되었다. 일반적으로 측정된 전원이 이상적이지 않고 고조파가 포함되어 있으며 센서의 노이즈 때문에 동기좌표계 PLL의 피드백 루프에는 LPF를 사용하고 있다. 그러므로 과도상태의 빠른 동특성을 얻기 위해서 LPF를 고려한 PLL시스템의 모델링을 제안하였다. 또한 전원의 급변 시에 빠른 위상각 검출을 위한 방법으로 자동으로 제어기 대역폭과 LPF의 차단주파수를 변동시키는 가변 파라미터 PLL방법을 제안하였다. 이를 시뮬레이션과 실험을 통해 검증하여 유효성을 보이고자 한다.

• ETRI Journal
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• 제28권6호
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• pp.770-776
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• 2006

This paper presents a hyperspectral imaging technique based on laser-induced fluorescence for non-invasive detection of tumorous tissue on mouse skin. Hyperspectral imaging sensors collect image data in a number of narrow, adjacent spectral bands. Such high-resolution measurement of spectral information reveals contiguous emission spectra at each image pixel useful for the characterization of constituent materials. The hyperspectral image data used in this study are fluorescence images of mouse skin consisting of 21 spectral bands in the visible spectrum of the wavelengths ranging from 440 nm to 640 nm. Fluorescence signal is measured with the use of laser excitation at 337 nm. An acousto-optic tunable filter (AOTF) is used to capture images at 10 nm intervals. All spectral band images are spatially registered with the reference band image at 490 nm to obtain exact pixel correspondences by compensating the spatial offsets caused by the refraction differences in AOTF at different wavelengths during the image capture procedure. The unique fluorescence spectral signatures demonstrate a good separation to differentiate malignant tumors from normal tissues for rapid detection of skin cancers without biopsy.