• 조명전기설비학회논문지
• /
• 제25권5호
• /
• pp.73-78
• /
• 2011

We developed a noise reduction algorithm for the measurement accuracy improvement of a fiber-optic distributed temperaure sensor system. The denoising technique is based on the wavelet transform. The proposed algorithm was applied to a FBG sensor output with the Gaussian line-fitting algorithm to minimize the output noise which originated from the intensity noise of the laser light source and the instability of signal porcessing. We confirmed the feasibility of the denoising algorithm by comparing the measurement results with those obtained with the Gaussian line-fitting algorithm only.

• 한국조명전기설비학회:학술대회논문집
• /
• 한국조명전기설비학회 2008년도 춘계학술대회 논문집
• /
• pp.383-386
• /
• 2008

We developed a fiber-optic Bragg grating sensor system using a SOA fiber laser for over heat detection in power systems. To compensate the nonlinear wavelength tuning of the fiber laser, we used fixed passband wavelengths from Fabry-Perot ITU filter as reference wavelengths. Gaussian line-fitting algorithm was also used to reduce the FBG peak detection error. Compared with a highest-peak-detection and a polynomial-fitting method, the proposed Gaussian fitting algorithm could drastically reduce the measurement errors. Also the SOA fiber laser made it possible to enhance the signal-to-noise-ratio even with several kilometers of lead fiber.

• Current Optics and Photonics
• /
• 제2권1호
• /
• pp.69-78
• /
• 2018

This paper presents a precise edge detection algorithm for the critical dimension (CD) measurement of a Thin-Film Transistor Liquid-Crystal Display (TFT-LCD) pattern. The sigmoid surface function is proposed to model the blurred step edge. This model can simultaneously find the position and geometry of the edge precisely. The nonlinear least squares fitting method (Levenberg-Marquardt method) is used to model the image intensity distribution into the proposed sigmoid blurred edge model. The suggested algorithm is verified by comparing the CD measurement repeatability from high-magnified blurry and noisy TFT-LCD images with those from the previous Laplacian of Gaussian (LoG) based sub-pixel edge detection algorithm and error function fitting method. The proposed fitting-based edge detection algorithm produces more precise results than the previous method. The suggested algorithm can be applied to in-line precision CD measurement for high-resolution display devices.

• 천문학회보
• /
• 제46권2호
• /
• pp.68.3-69
• /
• 2021

We present a novel profile stacking technique based on optimal profile decomposition of a 3D spectral line data cube, and its performance test using the HI data cubes of sample galaxies from HI galaxy surveys, THINGS and LITTLE THINGS. Compared to the previous approach which aligns all the spectra of a cube using their central velocities derived from either moment analysis, single Gaussian or hermite h3 polynomial fitting, the new method makes a profile decomposition of the profiles from which an optimal number of single Gaussian components is derived for each profile. The so-called superprofile which is derived by co-adding all the aligned profiles from which the other Gaussian models are subtracted is found to have weaker wings compared to the ones constructed in a typical manner. This could be due to the reduced number of asymmetric profiles in the new method. A practical test made on the HI data cubes of the THINGS and LITTLE THINGS galaxies shows that our new method can extract more mass of kinematically cold HI components in the galaxies than the previous results. Additionally, we fit a double Gaussian model to the superprofiles whose S/N is boosted, and quantify not only their profile shapes but derive the ratio of the Gaussian model parameters, such as the intensity ratio and velocity dispersion ratio of the narrower and broader Gaussian components. We discuss how the superprofile properties of the sample galaxies are correlated with their other physical properties, including star formation rate, stellar mass, metallicity, and gas mass.

• 한국분말재료학회지
• /
• 제10권5호
• /
• pp.318-324
• /
• 2003

The nano-scale crystallite sizes of uranium oxide powders in simulated spent fuel were measured by the neutron diffraction line broadening method in order to analyze the sintering behavior of the dry process fuel. The mixed $UO_2$ and fission product powders were dry-milled in an attritor for 30, 60, and 120 min. The diffraction patterns of the powders were obtained by using the high resolution powder diffractometer in the HANARO research reactor. Diffraction line broadening due to crystallite size was measured using various techniques such as the Stokes' deconvolution, profile fitting methods using Cauchy function, Gaussian function, and Voigt function, and the Warren-Averbach method. The non-uniform strain, stacking fault and twin probability were measured using the information from the diffraction pattern. The realistic crystallite size could be obtained after separation of the contribution from the non-uniform strain, stacking fault and twin.

• 조명전기설비학회논문지
• /
• 제20권5호
• /
• pp.64-71
• /
• 2006

전력설비의 비정상적인 온도변화를 감시할 목적으로 10개의 광섬유격자를 이용하여 $1[^{\circ}C]$ 이내의 온도분해능을 가지는 준분배형 광섬유 온도센서를 제작하였다. 파장가변 FP 필터를 스캔하여 얻어지는 PD 출력파형의 피크위치를 검색하여 광섬유격자 센서의 출력변화를 읽어내었고, 가우시안 line-fitting 알고리즘으로 광섬유격자의 반사스펙트럼 왜곡에 의한 영향을 보상하고 정밀도를 향상시켰다. 제작한 센서시스템과 기준 온도계로 사용한 thermocouple 간의 측정값 오차는 1[%] 이내이며, 선형화 오차는 약 0.37[%]으로 측정되었다.

• Journal of Astronomy and Space Sciences
• /
• 제4권1호
• /
• pp.35-45
• /
• 1987

The peculiar elliptical (EOp) galaxy NGC 4486 and two KOII comparison stars HR5450, HR6935 were observed spectroscopically using the 74-inch telescope and Image Tube at Mt. Stomlo Observatory. From the Gaussian Broadening Function, broadened spectrum of two comparison stars were computed for the range between wavelength 4800$\AA$ and 5400$\AA$. Velocity dispersions in the line of sight of M87 were obtained by visual fitting. The fitted velocity dispersion is 450 km/sec at the nucleus, 350km/sec at r=12", and 300km/sec at r=24". Using the photometric data and the central value of velocity dispersion, we determined the mass of M87. From <$r^{2/4}$ law and the Virial theorem the calculated total mass in $2.1\times10^{12}M_\odot$ and from the King Model $M=1.2\times10^{12}M_\odot$. And M/L ratio of M87 is about 30.

• 한국조명전기설비학회:학술대회논문집
• /
• 한국조명전기설비학회 2006년도 춘계학술대회 논문집
• /
• pp.86-90
• /
• 2006

We prosed a distributed fiber-optic sensor system with 10 fiber Bragg gratings, for over temperature protection relay in power systems. We applied Gaussian line-fitting algorithm to compensate the distortion effects in the wavelength-scanned Farby-Perot filter demodulation scheme. Compared with the highest-peak-detection method, the proposed algorithm was proved to minimize the random errors of distorted PD profiles. From experimental results, the overall measurement error was within 1 % compared with the reference thermocouple and the linearity error was less than 0.37 %.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• 제12권2호
• /
• pp.643-661
• /
• 2018

This paper proposes a novel algorithm for lane detection based on inverse perspective transformation and Kalman filter. A simple inverse perspective transformation method is presented to remove perspective effects and generate a top-view image. This method does not need to obtain the internal and external parameters of the camera. The Gaussian kernel function is used to convolute the image to highlight the lane lines, and then an iterative threshold method is used to segment the image. A searching method is applied in the top-view image obtained from the inverse perspective transformation to determine the lane points and their positions. Combining with feature voting mechanism, the detected lane points are fitted as a straight line. Kalman filter is then applied to optimize and track the lane lines and improve the detection robustness. The experimental results show that the proposed method works well in various road conditions and meet the real-time requirements.

• 조명전기설비학회논문지
• /
• 제24권2호
• /
• pp.86-91
• /
• 2010

광섬유 격자를 이용한 센서 네트워크를 이용하여 준분배형 전력설비 안전진단 시스템을 구성하였다. FBG를 이용한 센서는 한 개의 라인에 복수의 센서가 설치가능하며, 전자기 노이즈에 영향을 받지 않는 특성을 가진다. 광섬유 격자에서 반사되는 파장의 신호를 분석하기 위하여 InGaAs PD 어레이와 홀로그램 회절격자를 이용하여 구조가 간단하면서도 고속의 파장복조가 가능하도록 하였다. 제안한 시스템의 정확도를 개선하기 위해 가우시안 라인피팅을 적용하였고, 높은 파장 정밀도(4[pm])와 동작 안정성을 얻을 수 있음을 확인하였다.