• Title/Summary/Keyword: Gaussian field

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Development of the Algorithm for Traffic Accident Auto-Detection in Signalized Intersection (신호교차로 내 실시간 교통사고 자동검지 알고리즘 개발)

  • O, Ju-Taek;Im, Jae-Geuk;Hwang, Bo-Hui
    • Journal of Korean Society of Transportation
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    • v.27 no.5
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    • pp.97-111
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    • 2009
  • Image-based traffic information collection systems have entered widespread adoption and use in many countries since these systems are not only capable of replacing existing loop-based detectors which have limitations in management and administration, but are also capable of providing and managing a wide variety of traffic related information. In addition, these systems are expanding rapidly in terms of purpose and scope of use. Currently, the utilization of image processing technology in the field of traffic accident management is limited to installing surveillance cameras on locations where traffic accidents are expected to occur and digitalizing of recorded data. Accurately recording the sequence of situations around a traffic accident in a signal intersection and then objectively and clearly analyzing how such accident occurred is more urgent and important than anything else in resolving a traffic accident. Therefore, in this research, we intend to present a technology capable of overcoming problems in which advanced existing technologies exhibited limitations in handling real-time due to large data capacity such as object separation of vehicles and tracking, which pose difficulties due to environmental diversities and changes at a signal intersection with complex traffic situations, as pointed out by many past researches while presenting and implementing an active and environmentally adaptive methodology capable of effectively reducing false detection situations which frequently occur even with the Gaussian complex model analytical method which has been considered the best among well-known environmental obstacle reduction methods. To prove that the technology developed by this research has performance advantage over existing automatic traffic accident recording systems, a test was performed by entering image data from an actually operating crossroad online in real-time. The test results were compared with the performance of other existing technologies.

Characteristics of Static Shift in 3-D MT Inversion (3차원 MT 역산에서 정적효과의 특성 고찰)

  • Lee Tae Jong;Uchida Toshihiro;Sasaki Yutaka;Song Yoonho
    • Geophysics and Geophysical Exploration
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    • v.6 no.4
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    • pp.199-206
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    • 2003
  • Characteristics of the static shift are discussed by comparing the three-dimensional MT inversion with/without static shift parameterization. The galvanic distortion by small-scale shallow feature often leads severe distortion in inverted resistivity structures. The new inversion algorithm is applied to four numerical data sets contaminated by different amount of static shift. In real field data interpretations, we generally do not have any a-priori information about how much the data contains the static shift. In this study, we developed an algorithm for finding both Lagrangian multiplier for smoothness and the trade-off parameter for static shift, simultaneously in 3-D MT inversion. Applications of this inversion routine for the numerical data sets showed quite reasonable estimation of static shift parameters without any a-priori information. The inversion scheme is successfully applied to all the four data sets, even when the static shift does not obey the Gaussian distribution. Allowing the static shift parameters have non-zero degree of freedom to the inversion, we could get more accurate block resistivities as well as static shifts in the data. When inversion does not consider the static shift as inversion parameters (conventional MT inversion), the block resistivities on the surface are modified considerably to match possible static shift. The inhomogeneous blocks on the surface can generate the static shift at low frequencies. By those mechanisms, the conventional 3-D MT inversion can reconstruct the resistivity structures to some extent in the deeper parts even when moderate static shifts are in the data. As frequency increased, however, the galvanic distortion is not frequency independent any more, and thus the conventional inversion failed to fit the apparent resistivity and phase, especially when strong static shift is added. Even in such case, however, reasonable estimation of block resistivity as well as static shift parameters were obtained by 3-D MT inversion with static shift parameterization.

Design and Fabrication of Binary Diffractive Optical Elements for the Creation of Pseudorandom Dot Arrays of Uniform Brightness (균일 밝기 랜덤 도트 어레이 생성을 위한 이진 회절광학소자 설계 및 제작)

  • Lee, Soo Yeon;Lee, Jun Ho;Kim, Young-Gwang;Rhee, Hyug-Gyo;Lee, Munseob
    • Korean Journal of Optics and Photonics
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    • v.33 no.6
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    • pp.267-274
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    • 2022
  • In this paper, we report the design and fabrication of binary diffractive optical elements (DOEs) for random-dot-pattern projection for Schlieren imaging. We selected the binary phase level and a pitch of 10 ㎛ for the DOE, based on cost effectiveness and ease of manufacture. We designed the binary DOE using an iterative Fourier-transform algorithm with binary phase optimization. During initial optimization, we applied a computer-generated pseudorandom dot pattern of uniform intensity as a target pattern, and found significant intensity nonuniformity across the field. Based on the evaluation of the initial optimization, we weighted the target random dot pattern with Gaussian profiles to improve the intensity uniformity, resulting in the improvement of uniformity from 52.7% to 90.8%. We verified the design performance by fabricating the designed binary DOE and a beam projector, to which the same was applied. The verification confirmed that the projector produced over 10,000 random dot patterns over 430 mm × 430 mm at a distance of 5 meters, as designed, but had a slightly less uniformity of 84.5%. The fabrication errors of the DOE, mainly edge blurring and spacing errors, were strong possibilities for the difference.

Comparison of ANN model's prediction performance according to the level of data uncertainty in water distribution network (상수도관망 내 데이터 불확실성에 따른 절점 압력 예측 ANN 모델 수행 성능 비교)

  • Jang, Hyewoon;Jung, Donghwi;Jun, Sanghoon
    • Journal of Korea Water Resources Association
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    • v.55 no.spc1
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    • pp.1295-1303
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    • 2022
  • As the role of water distribution networks (WDNs) becomes more important, identifying abnormal events (e.g., pipe burst) rapidly and accurately is required. Since existing approaches such as field equipment-based detection methods have several limitations, model-based methods (e.g., machine learning based detection model) that identify abnormal events using hydraulic simulation models have been developed. However, no previous work has examined the impact of data uncertainties on the results. Thus, this study compares the effects of measurement error-induced pressure data uncertainty in WDNs. An artificial neural network (ANN) is used to predict nodal pressures and measurement errors are generated by using cumulative density function inverse sampling method that follows Gaussian distribution. Total of nine conditions (3 input datasets × 3 output datasets) are considered in the ANN model to investigate the impact of measurement error size on the prediction results. The results have shown that higher data uncertainty decreased ANN model's prediction accuracy. Also, the measurement error of output data had more impact on the model performance than input data that for a same measurement error size on the input and output data, the prediction accuracy was 72.25% and 38.61%, respectively. Thus, to increase ANN models prediction performance, reducing the magnitude of measurement errors of the output pressure node is considered to be more important than input node.

Comparative Evaluation of Behavior Analysis of Rectangular Jet and Two-dimensional Jet (사각형제트와 2차원제트의 거동해석의 비교 평가)

  • Kwon, Seok Jae;Cho, Hong Yeon;Seo, Il Won
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.26 no.6B
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    • pp.641-649
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    • 2006
  • The behavior of a three-dimensional pure rectangular water jet with aspect ratio of 10 was experimentally investigated based on the results of the mean velocity field obtained by PIV. The saddle back distribution was observed in the lateral distribution along the major axis. The theoretical centerline velocity equation derived from the point source concept using the spreading rate for the axisymmetric jet was in good agreement with the measured centerline velocity and gave the division of the potential core region, two-dimensional region, and axisymmetric region. The range of the two-dimensional region divided by the criterion of the theoretical centerline velocity decay for the aspect ratio of 10 was observed to be smaller than that of the transition region. The applicability of the two-dimensional model to the behavior of the rectangular jet with low aspect ratio or the wastewater discharged from a multiport diffuser in the deep water of real ocean may result in significant error in the transition and axisymmetric regions after the two-dimensional region. In the two-dimensional region, the Gaussian constant tended to be conserved, and the spreading rate slightly decreased at the end of the two-dimensional region. The normalized turbulent intensity along the centerline of the jet initially abruptly increased and showed relatively higher intensity for higher Reynolds number.

Identifying Analog Gauge Needle Objects Based on Image Processing for a Remote Survey of Maritime Autonomous Surface Ships (자율운항선박의 원격검사를 위한 영상처리 기반의 아날로그 게이지 지시바늘 객체의 식별)

  • Hyun-Woo Lee;Jeong-Bin Yim
    • Journal of Navigation and Port Research
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    • v.47 no.6
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    • pp.410-418
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    • 2023
  • Recently, advancements and commercialization in the field of maritime autonomous surface ships (MASS) has rapidly progressed. Concurrently, studies are also underway to develop methods for automatically surveying the condition of various on-board equipment remotely to ensure the navigational safety of MASS. One key issue that has gained prominence is the method to obtain values from analog gauges installed in various equipment through image processing. This approach has the advantage of enabling the non-contact detection of gauge values without modifying or changing already installed or planned equipment, eliminating the need for type approval changes from shipping classifications. The objective of this study was to identify a dynamically changing indicator needle within noisy images of analog gauges. The needle object must be identified because its position significantly affects the accurate reading of gauge values. An analog pressure gauge attached to an emergency fire pump model was used for image capture to identify the needle object. The acquired images were pre-processed through Gaussian filtering, thresholding, and morphological operations. The needle object was then identified through Hough Transform. The experimental results confirmed that the center and object of the indicator needle could be identified in images of noisy analog gauges. The findings suggest that the image processing method applied in this study can be utilized for shape identification in analog gauges installed on ships. This study is expected to be applicable as an image processing method for the automatic remote survey of MASS.

Correlation Analysis of Rail Surface Defects and Rail Internal Cracks (레일표면결함과 레일내부균열의 상관관계 분석)

  • Jung-Youl Choi;Jae-Min Han;Young-Ki Kim
    • The Journal of the Convergence on Culture Technology
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    • v.10 no.1
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    • pp.585-590
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    • 2024
  • In this study, rail surface defects are increasing due to the aging of urban railway rails, but in the detailed guidelines for track performance evaluation established by the country, rail surface damage is inspected with the naked eye of engineers and simple measuring tools. With the recent enactment of the Track Diagnosis Act, a large budget has been invested and the volume of rail diagnosis is rapidly increasing, but it is difficult to secure the reliability of diagnosis results using labor-intensive visual inspection techniques. It is very important to discover defects in the rail surface through periodic track tours and visual inspection. However, evaluating the severity of defects on the rail surface based on the subjective judgment of the inspector has significant limitations in predicting damage inside the rail. In this study, the rail internal crack characteristics due to rail surface damage were studied. In field measurements, rail surface damage locations were selected, samples of various damage types were collected, and the rail surface damage status was evaluated. In indoor testing, we intend to analyze the correlation between rail surface defects and internal defects using a electron scanning microscope (SEM). To determine the crack growth rate of urban railway rails currently in use, the Gaussian probability density function was applied and analyzed.

Effect of Lead Content on Atomic Structures of Pb-bearing Sodium Silicate Glasses: A View from 29Si NMR Spectroscopy (납 함량에 따른 비정질 Pb-Na 규산염의 원자 구조에 대한 고상 핵자기 공명 분광분석 연구)

  • Lee, Seoyoung;Lee, Sung Keun
    • Korean Journal of Mineralogy and Petrology
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    • v.34 no.3
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    • pp.157-167
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    • 2021
  • Lead (Pb) is one of the key trace elements, exhibiting a peculiar partitioning behavior into silicate melts in contact with minerals. Partitioning behaviors of Pb between silicate mineral and melt have been known to depend on melt composition and thus, the atomic structures of corresponding silicate liquids. Despite the importance, detailed structural studies of Pb-bearing silicate melts are still lacking due to experimental difficulties. Here, we explored the effect of lead content on the atomic structures, particularly the evolution of silicate networks in Pb-bearing sodium metasilicate ([(PbO)x(Na2O)1-x]·SiO2) glasses as a model system for trace metal bearing natural silicate melts, using 29Si solid-state nuclear magnetic resonance (NMR) spectroscopy. As the PbO content increases, the 29Si peak widths increase, and the maximum peak positions shift from -76.2, -77.8, -80.3, -81.5, -84.6, to -87.7 ppm with increasing PbO contents of 0, 0.25, 0.5, 0.67, 0.86, and 1, respectively. The 29Si MAS NMR spectra for the glasses were simulated with Gaussian functions for Qn species (SiO4 tetrahedra with n BOs) for providing quantitative resolution. The simulation results reveal the evolution of each Qn species with varying PbO content. Na-endmember Na2SiO3 glass consists of predominant Q2 species together with equal proportions of Q1 and Q3. As Pb replaces Na, the fraction of Q2 species tends to decrease, while those for Q1 and Q3 species increase indicating an increase in disproportionation among Qn species. Simulation results on the 29Si NMR spectrum showed increases in structural disorder and chemical disorder as evidenced by an increase in disproportionation factor with an increase in average cation field strengths of the network modifying cations. Changes in the topological and configurational disorder of the model silicate melt by Pb imply an intrinsic origin of macroscopic properties such as element partitioning behavior.

Quantitative Conductivity Estimation Error due to Statistical Noise in Complex $B_1{^+}$ Map (정량적 도전율측정의 오차와 $B_1{^+}$ map의 노이즈에 관한 분석)

  • Shin, Jaewook;Lee, Joonsung;Kim, Min-Oh;Choi, Narae;Seo, Jin Keun;Kim, Dong-Hyun
    • Investigative Magnetic Resonance Imaging
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    • v.18 no.4
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    • pp.303-313
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    • 2014
  • Purpose : In-vivo conductivity reconstruction using transmit field ($B_1{^+}$) information of MRI was proposed. We assessed the accuracy of conductivity reconstruction in the presence of statistical noise in complex $B_1{^+}$ map and provided a parametric model of the conductivity-to-noise ratio value. Materials and Methods: The $B_1{^+}$ distribution was simulated for a cylindrical phantom model. By adding complex Gaussian noise to the simulated $B_1{^+}$ map, quantitative conductivity estimation error was evaluated. The quantitative evaluation process was repeated over several different parameters such as Larmor frequency, object radius and SNR of $B_1{^+}$ map. A parametric model for the conductivity-to-noise ratio was developed according to these various parameters. Results: According to the simulation results, conductivity estimation is more sensitive to statistical noise in $B_1{^+}$ phase than to noise in $B_1{^+}$ magnitude. The conductivity estimate of the object of interest does not depend on the external object surrounding it. The conductivity-to-noise ratio is proportional to the signal-to-noise ratio of the $B_1{^+}$ map, Larmor frequency, the conductivity value itself and the number of averaged pixels. To estimate accurate conductivity value of the targeted tissue, SNR of $B_1{^+}$ map and adequate filtering size have to be taken into account for conductivity reconstruction process. In addition, the simulation result was verified at 3T conventional MRI scanner. Conclusion: Through all these relationships, quantitative conductivity estimation error due to statistical noise in $B_1{^+}$ map is modeled. By using this model, further issues regarding filtering and reconstruction algorithms can be investigated for MREPT.

The Spin-Rotation Interaction of the Proton and the Fluorine Nucleus in the Tetrahedral Spherical Top Molecules

  • Lee, Sang-Soo;Ozier, Irving;Ramsey, N.F.
    • Nuclear Engineering and Technology
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    • v.5 no.1
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    • pp.38-43
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    • 1973
  • The spin-rotation constants of the proton and tile fluorine nucleus in C $H_4$, Si $H_4$, Ge $H_4$, C $F_4$, Si $F_4$ and Ge $F_4$ were determined experimentally by the molecular beam magnetic resonance method. From the Hamiltonian and the high field approximation, the quantized energy level is given by the following equation. W $m_{I}$ $m_{J}$=- $g_{I}$ $m_{I}$H- $g_{J}$ $m_{J}$H- $C_{av}$ $m_{I}$ $m_{J}$, where $c_{av}$ is one third of the trace of the C tensor. In the nuclear resonance experiment, the proton and the fluorine nuclear resonance curves consist of many unresolved lines given by v=- $g_{J}$H- $C_{av}$ $m_{I}$, and a Gaussian approximation is made to correlate $c_{av}$ to the experimentally obtained half-width of the resonance curve. In the rotational resonance experiment, the five resonance peaks as predicted by v=- $g_{I}$H- $c_{av}$ $m_{I}$, $m_{I}$=0, $\pm$1 and $\pm$2, were all observed. The magnitude of car was determined by measuring the frequency distance between two adjacent peaks. The sign of $c_{av}$ was determined by the side peak suppression technique. The technique is described, and the sign and magnitude of the spin-rotation constant cav are summarized as following: for C $H_4$ -10.3$\pm$0.4tHz(from the rotational resonance), for SiH +3.71$\pm$0.08kHz(from the nuclear resonance), for Ge $H_4$+3.79$\pm$0.13kHz(from the nuclear resonance), for C $F_4$, -6.81$\pm$0.08kHz(from the rotational resonance), for Si $F_4$, -2.46$\pm$0.06kHz(from the rotational resonance), and finally for Ge $F_4$-1.84$\pm$0.04kHz(from the rotational resonance).onal resonance).esonance).

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