• 제목/요약/키워드: field projection method

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Conversion of Fisheye Image to Perspective Image Using Nonlinear Scaling Function (비선형 스케일링 함수를 이용한 어안 영상의 원근 변환)

  • Kim, Tae-Woo;Cho, Tae-Kyung
    • Journal of the Korea Academia-Industrial cooperation Society
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    • 제10권1호
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    • pp.117-121
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    • 2009
  • The fisheye image acquired with a fisheye camera has wider field of view than a general use camera. But large distortion of the object in the image requires conversion of the fisheye image to the perspective image because of user's difficult perception. The existing Ishii's method[1] has the problem that the object can has sire and geometrical distortion in the transformed image because it uses equidistance projection. This paper presented a conversion technique of the fisheye image to the perspective image using sealing function. In the experiments, it was shown that our method reduced size and geometrical distortion by applying the scaling function.

Development of Non-Adhesive, Non-Contact Inclinometer Slope Laser Measuring (ISLM) System and its Control Algorithm (레이저를 이용한 기울기 측정 장치 및 이의 제어 방법 개발)

  • Kim, Jae-Hyun;Lee, Seong-Min;Lee, Kihak;Choi, Woo-Suk;Baek, Seung-hoon
    • Journal of Korean Association for Spatial Structures
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    • 제21권3호
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    • pp.25-34
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    • 2021
  • This study develops a new device system for measuring a slope of object with non-adhesive, non-contact and non-face-to-face, namely Inclinometer Slope Laser Measuring (ISLM), that is applicable in the field. This system includes cradle, laser, camera, and computer and the filming and is performed after laser projection at programmed intervals. After measuring the amount of displacement converted to numerical values, these values can then be transferred to the office using the selected data transmission method. The obtained results from the test carried out to verify the reliability of the ISLM system indicated that the ISLM system can measure with accurately level of 0.1mm/Pixel at 1m distance and when increasing the camera resolution, the precision might increase proportionally. Therefore, the proposed measure system may widely apply on-site for various constructions, especially, in the case of object with very high surface temperature where exhibits difficulty to directly measure the adjacent structures. However, due to the sensitive reaction to the illuminance, this method can be applied with caution at times of large changes in illuminance, such as at dawn and at dusk.

A real-time unmeasured dynamic response prediction for nuclear facility pressure pipeline system

  • Seungin Oh ;Hyunwoo Baek ;Kang-Heon Lee ;Dae-Sic Jang;Jihyun Jun ;Jin-Gyun Kim
    • Nuclear Engineering and Technology
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    • 제55권7호
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    • pp.2642-2649
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    • 2023
  • A real-time unmeasured dynamic response prediction process for the nuclear power plant pressure pipeline is proposed and its performance is tested in the test-loop system (KAERI). The aim of the process is to predict unmeasurable or unreachable dynamic responses such as acceleration, velocity, and displacement by using a limited amount of directly measured physical responses. It is achieved by combining a well-constructed finite element model and robust inverse force identification algorithm. The pressure pipeline system is described by using the displacement-pressure vibro-acoustic formulation to consider fully filled liquid effect inside the pipeline structure. A robust multiphysics modal projection technique is employed for the real-time sensor synchronized prediction. The inverse force identification method is also derived and employed by using Bathe's time integration method to identify the full-field responses of the target system from the modal domain computation. To validate the performance of the proposed process, an experimental test is extensively performed on the nuclear power plant pressure pipeline test-loop under operation conditions. The results show that the proposed identification process could well estimate the unmeasured acceleration in both frequency and time domain faster than 32,768 samples per sec.

Sensitivity analysis of grid size for bubble flow field analysis using image analysis methods (영상분석기법 기반 기포유동장 해석을 위한 격자의 민감도 분석)

  • Kim, Sung Jung;Jang, Chang-Lae
    • Journal of Korea Water Resources Association
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    • 제57권8호
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    • pp.549-559
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    • 2024
  • This study aims to investigate the feasibility of using image analysis methods to examine the flow characteristics of air bubbles discharged underwater. A bubble screen was created using multiple nozzles in a laboratory flume filled with stagnant water. The flow characteristics of the bubbles were analyzed, and the suitability of the analysis method was evaluated. Several parameters, such as projection area ratio and depth ratio, were defined to conduct laboratory experiments and analyze the flow characteristics of the bubbles. Correlation and regression analyses were performed to assess the relationships between various variables. Specifically, the correlation between the bubble's projection area and its rising speed across eight water depth ratios was examined. The results indicated that as the depth ratio increased, the bubble size exhibited a linear increase with a strong correlation as it rose to the water surface due to pressure effects. Regarding the sensitivity of different grid sizes in the ten analysis grids when applying image analysis methods, it was observed that the sensitivity to grid size based on the projection area ratio (0.09~0.96) was not significant. These findings suggest that image analysis techniques can be effectively utilized to observe the flow characteristics of bubbles.

Active mass driver control system for suppressing wind-induced vibration of the Canton Tower

  • Xu, Huai-Bing;Zhang, Chun-Wei;Li, Hui;Tan, Ping;Ou, Jin-Ping;Zhou, Fu-Lin
    • Smart Structures and Systems
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    • 제13권2호
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    • pp.281-303
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    • 2014
  • In order to suppress the wind-induced vibrations of the Canton Tower, a pair of active mass driver (AMD) systems has been installed on the top of the main structure. The structural principal directions in which the bending modes of the structure are uncoupled are proposed and verified based on the orthogonal projection approach. For the vibration control design in the principal X direction, the simplified model of the structure is developed based on the finite element model and modified according to the field measurements under wind excitations. The AMD system driven by permanent magnet synchronous linear motors are adopted. The dynamical models of the AMD subsystems are determined according to the open-loop test results by using nonlinear least square fitting method. The continuous variable gain feedback (VGF) control strategy is adopted to make the AMD system adaptive to the variation in the intensity of wind excitations. Finally, the field tests of free vibration control are carried out. The field test results of AMD control show that the damping ratio of the first vibration mode increases up to 11 times of the original value without control.

Stability Analysis of Open Pit Slopes in the Pasir Coal Field, Indonesia (인도네시아 Pasir 탄전에서의 노천채탄장 사면의 안전성해석)

  • 정소걸;선우춘;한공창;신희순;박연준
    • Proceedings of the Korean Society for Rock Mechanics Conference
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    • 한국암반공학회 2000년도 암반공학문제의 수치해석(Numerical Analysis in Rock Engineering Problems)
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    • pp.183-193
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    • 2000
  • A series of studies such as geological logging data analysis, detailed geological survey, rock mass evaluation, in-situ and laboratory tests, rock strength and mechanical properties of the rock were concerned. The stability of the slope were carried out inorder to design the pit slope and individual benches using the stereographic projection analysis and numerical methods in Roto Pit of Pasir coal fetid. The bedding plane was one of the major discontinuities in the Roto Pit and the dip of which is about $60^{\circ}$in the northern part and $83^{\circ}$in the southern part. The dip of bedding becomes steeper from north to south. The plane and toppling failures are presented in many slopes. In laboratory test the average uniaxial compressive strength of mudstone was 9 MPa and that of weak sandstone was 10 MPa. In-situ test showed that the rocks of Roto north mining area are mostly weak enough to be classified in grade from R2(weak) to R3(medium strong weak) and the coal is classified in grades from R1(Very weak) to R2(Weak). The detailed stability analysis were carried out on 4 areas of Roto north(east, west, south and north), and 2 areas of Roto south(east and west). In this paper, the minimum factor of safety was set to 1.2 which is a general criterion for open pit mines. Using the stereographic projection analysis and the limit equilibrium method, slope angles were calculated as 30~$36^{\circ}$for a factor of safety greater than 1.2. Then these results were re-evaluated by numerical analysis using FLAC. The final slope angles were determined by rational described abode. A final slope of 34 degrees can guarantee the stability for the eastern part of the Roto north area, 33 degrees for the western part, 35 degrees for the northern part and 35 degrees for the southern part. For the Roto south area, 36 degrees was suggested for both sides of the pit. Once the pit slope is designed based on the stability analysis and the safety measures. the stability of 니ope should be checked periodically during the mining operations. Because the slope face will be exposed long time to the rain fall, a study such aspreventive measures against weathering and erosion is highly recommended to be implemented.

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Numerical Simulation of Solitary Wave Run-up with an Internal Wave-Maker of Navier-Stokes Equations Model (내부조파기법을 활용한 Navier-Stokes 방정식 모형의 고립파 처오름 수치모의)

  • Ha, Tae-Min;Kim, Hyung-Jun;Cho, Yong-Sik
    • Journal of Korea Water Resources Association
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    • 제43권9호
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    • pp.801-811
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    • 2010
  • A three-dimensional numerical model called NEWTANK is employed to investigate solitary wave run-up with an internal wave-maker on a steep slope. The numerical model solves the spatially averaged Navier-Stokes equations for two-phase flows. The LES (large-eddy-simulation) approach is adopted to model the turbulence effect by using the Smagorinsky SGS (sub-grid scale) closure model. A two-step projection method is adopted in numerical solutions, aided by the Bi-CGSTAB (Bi-Conjugate Gradient Stabilized) method to solve the pressure Poisson equation for the filtered pressure field. The second-order accurate VOF (volume-of-fluid) method is used to track the distorted and broken free surface. A solitary wave is first internally generated and propagated over a constant water depth in the three-dimensional domain. Numerically predicted results are compared with analytical solutions and numerical errors are analyzed in detail. The model is then applied to study solitary wave run-up on a steep slope and the obtained results are compared with available laboratory measurements.

Stability of a Natural Slope in Sedimentary Rocks (퇴적암 지역의 자연사면 안정성)

  • 권오일;김교원;박덕근
    • The Journal of Engineering Geology
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    • 제10권3호
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    • pp.205-216
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    • 2000
  • An unstable natural slope located at Icheon-Ri, Dasa-Eup, Dalseong-Kun which has been severely cracked during heavy rain fall in September, 1998, was investigated and analysed for remedial measures. Various geological data were obtained by performing a surface geological survey, a ground penetrating radar(GPR) exploration, four geotechnical borings with field and laboratory tests, and the precipitation records were also reviewed. Based on the these data, the probable sliding plane was determined as a bedding plane with dip angle of 20 to 25 degrees between sandstone and shale layers at depth of 6 to 8 meters. By performing back analyses with the limit equilibrium method, the friction angle and cohesion of the sliding plane were determined as 18$^{\circ}$ and 0, respectively. Based on these results, a series of stability analyses such as stereo-graphic projection method, limiting equilibrium method and numerical method were carried out. The remedial measures for the unstable slope were selected based on the results of the limit equilibrium analyses by considering various conditions expected at the site. Ground grouting or anchoring method with proper surface drainage systems could be employed for the long term safety of the slope.

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A Study on the Demand for Nurse Anesthetists in Korea (우리나라 종합병원과 일반병원의 마취 전문간호사 수요분석)

  • Shin Sung-Rae;Oh Pok-Ja
    • Journal of Korean Academy of Fundamentals of Nursing
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    • 제11권2호
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    • pp.195-202
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    • 2004
  • Purpose: This descriptive study was conducted to project the number of nurse anesthetists needed in hospital settings, up to the year 2015. Method: Necessary data and information were collected from various funded reports, professional literature, web sites and personal visits to national and private institutions. The number of nurse anesthetists needed was projected after considering the total number of cases requiring anesthesia including deliveries, workload ratio for caesarean section to total number of deliveries, and percent of deliveries requiring and anesthesia. Result: The projected number of nurse anesthetists needed for hospital settings are as follows: 1. The number of registered anesthesia personnel in Korea in 2002 was 2,481 anesthesiologists and 543 nurse anesthetists but only 60% of anesthesiologists and 30% of nurse anesthetists (147) were actually practicing in the field of surgery. 2. By the year 2015, the total number of projected nurse anesthetists needed in hospital settings will be between 214 and 265. Conclusion: In order to match the supply to the need, the professional organizations should direct efforts towards enacting legislation. Educational systems should identify strategies to initiating an adequate number of nurse anesthetist programs at the master's level as well as standardizing curriculums across programs.

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Peridynamic analysis of dynamic fracture behaviors in FGMs with different gradient directions

  • Kou, Miaomiao;Bi, Jing;Yuan, Binhang;Wang, Yunteng
    • Structural Engineering and Mechanics
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    • 제75권3호
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    • pp.339-356
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    • 2020
  • In this article, a developed bond-based peridynamic model for functionally graded materials (FGMs) is proposed to simulate the dynamic fracture behaviors in FGMs. In the developed bond-based peridynamic model for FGMs, bonds are categorized into three different types, including transverse directionally peridynamic bond, gradient directionally peridynamic bond and arbitrary directionally peridynamic bond, according to the geometrical relationship between directions of peridynamic bonds and gradient bonds in FGMs. The peridynamic micromodulus in the gradient directionally and arbitrary directionally peridynamic bonds can be determined using the weighted projection method. Firstly, the standard bond-based peridynamic simulations of crack propagation and branching in the homogeneous PMMA plate are performed for validations, and the results are in good agreement with the previous experimental observations and the previous phase-field numerical results. Then, the numerical study of crack initiation, propagation and branching in FGMs are conducted using the developed bond-based peridynamic model, and the influence of gradient direction on the dynamic fracture behaviors, such as crack patterns and crack tip propagation speed, in FGMs is systematically studied. Finally, numerical results reveal that crack branching in FGMs under dynamic loading conditions is easier to occur as the gradient angle decreases, which is measured by the gradient direction and direction of the initial crack.