• Proceedings of the Korea Water Resources Association Conference
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• 2010.05a
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• pp.457-461
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• 2010

소하천에서의 효율적인 유량측정 수행을 위해서 K-water(한국수자원공사) 충청지역본부에서는 금강유역의 보청천 지류인 곰쟁이천에 원격유량측정시설 개념의 위어(weir)를 이용한 고정단면 시설물을 2006년도에 설치하였으며, 2007년부터 2009년까지 시설물 직하류에서 도섭을 통한 유량측정을 실시하였고 3차원 흐름해석 결과와의 비교를 통해 소하천 원격유량측정시설의 적정성을 분석하였다. 총 55회의 유량측정 성과를 이용하여 수위-유량 관계곡선식을 산정하였으며, FLOW-3D를 이용하여 3차원 흐름해석을 실시하였다. Francis 유량산정 공식인 Q=$1.84bH^{3/2}$을 통해 계산되는 수위별 유량, 유량측정 성과에 의한 수위-유량 관계곡선식, 그리고 FLOW-3D로부터 계산된 수위별 유량을 비교하였으며, 실측유량과 계산된 유량의 차이를 비교 검토하였다. 이러한 비교 검토를 통해 소유량 구간에 대해서는 원격유량측정시설의 적정성을 확인할 수 있었으며, 갈수시 미소유량이 흐르는 소하천에 위치한 지점에 대해서는 인력 및 비용이 많이 소요되는 도섭을 통한 직접 유량측정 수행보다는 검증된 유량측정시설(위어, 파샬플룸 등)을 통한 유량측정이 더욱 효과적인 것으로 판단되었다.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.33 no.2
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• pp.433-442
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• 2013

This paper presents experimental research work for the evaluation of one-dimensional and two-dimensional acoustic source locations with 50m length of a precast prestressed concrete box girder. Acoustic events are generated by the impacts of Schmidt Hammer and the impact signals are detected by acoustic emission sensors mounted on the concrete web surface of PSC box girder with the average spacing of 9.34m. Based on the amplitude of detected acoustic signals, considering the noises developed in PSC box girder bridges, the arrival times of acoustic signals are estimated by the first arrival times of 0Volt, 0.5Volt, and 1.0Volt amplitude in each signal. Using Least Square Method, the velocities and the source locations of acoustic signals are evaluated. Based on the test results, the spacing of AE sensors and the AE sensor networks are discussed to reduce the source location errors.

• The Journal of the Acoustical Society of Korea
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• v.20 no.2
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• pp.86-92
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• 2001

Various array processing techniques to identify the noise source position or bearing have been developed. Typical array processing techniques which are based on time delay between received signals at two sensors, are classified as conventional beamforming, correlation function and NAH (Near-Field Acoustic Holography) techniques which have their own characteristics with respect to application field and signal processing method. In this study, correlation function technique which could be applied for broadband noise source detection, is adopted and the effective detection technique is proposed considering the effects of source bandwidth and measurement noise correlation of noise sources. The validity of the Proposed technique is evaluated using the 3-dimensional nonlinear any which does not give 3-dimensional Position or bearing ambiguity

• Transactions of the Korean Society of Mechanical Engineers A
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• v.41 no.10
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• pp.949-957
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• 2017

A laser-vision-based height measurement system is developed and implemented for the inspection of two-step variable valve lift module assemblies. The proposed laser-vision sensor module is designed based on the principle of laser triangulation. This paper summarizes the work on 3D point cloud data collection and height difference measurements. The configuration of the measurement system and the proposed height measurement algorithm are described and analyzed in detail. Additional measurement experiments on the height differences of valves and lash adjusters of a two-step variable valve lift module were implemented repeatedly to evaluate the accuracy and repeatability of the proposed measurement system. Experimental results show that the proposed laser-vision-based height measurement system achieves high accuracy, repeatability, and stabilization for the inspection of two-step variable valve lift module assemblies.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.12C
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• pp.1157-1164
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• 2006

In this paper, we proposed a method for measuring accurate positions and sizes of package and balls in a micro BGA. To find defects of BGA accurately, we focused on finding positions of package and balls. After labeling, we detected connected components of package and balls using feature parameters. After the detection of package component, we measured position and size of package by employing rectangular model which was constructed by the package information. After the detection of the ball components, we measured positions and diameters of balls by employing circular models which were constructed by the ball informations. We did calibration based on landmarks to measure real length, and we compared the measured results with the SEM data. Finally, we found that the accuracy of the proposed method is 94% in terms of ball's radius.

• Proceedings of the Korean Society for Cognitive Science Conference
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• 2005.05a
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• pp.228-232
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• 2005

최근의 연구에서 Li. Brenner, Cornelissen과 Kim (2002)은 추적 눈 운동 동안의 2차원 모양지각이 망막에 형성된 이미지 내용을 그대로 반영한다는 것을 보여 주었는데, 이러한 연구는 2차원 모양판단에 있어서 눈 운동 정보가 전혀 고려되지 않았음을 시사한다. 이와 같은 실험실 연구와 달리, 실제 생활에서 2차원 모양지각의 왜곡은 대부분의 경우에 발생하지 않는데, 가능한 한 가지 이유는 실험실 연구에서 사용된 자극의 경우에 참조대상이 존재하지 않는데 비하여, 실제 생활에서는 다양한 참조대상이 목표대상의 주변에 존재하기 때문이다. 목표대상과 참조대상의 상대적인 위치관계는 추적 눈 운동 동안에 망막에서도 그대로 유지되는데 시각체계가 이러한 안정적인 관계를 목표 대상의 모양을 지각할 때에 이용할 가능성이 있다. 본 연구에서는 다양한 참조대상을 이용하여 이러한 가능성을 검증하였다. 특히, 피험자의 눈 운동을 눈 운동 측정기를 이용하여 측정하였으며, 적절한 눈 운동을 수행한 시행에서의 데이터만 분석에 사용하였다.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.31 no.4
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• pp.207-213
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• 2018

This paper investigates applicability of Microsoft $Kinect^{(R)}$, RGB-depth camera, to implement a 3D image and spatial information for sensing a target. The relationship between the image of the Kinect camera and the pixel coordinate system is formulated. The calibration of the camera provides the depth and RGB information of the target. The intrinsic parameters are calculated through a checker board experiment and focal length, principal point, and distortion coefficient are obtained. The extrinsic parameters regarding the relationship between the two Kinect cameras consist of rotational matrix and translational vector. The spatial images of 2D projection space are converted to a 3D images, resulting on spatial information on the basis of the depth and RGB information. The measurement is verified through comparison with the length and location of the 2D images of the target structure.

• Smart Media Journal
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• v.7 no.2
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• pp.15-22
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• 2018

Pupil tracking technologies can be used as an efficient information provider means that provides convenience to the user by connecting with a smart device. In this paper, we measure the distance of user gaze point using the pupil tracking device which produced by Pupil-labs, also shows the experimental result with analyzing accuracy and precision. Based on that the pupil gaze point location which tracked by pupil tracking device is compared with object target in terms of error. Since the mobile pupil tracking device is also one kind of camera, we have to perform the calibration before using the device. Not only generally used 2-dimensional calibration, but also 3-dimensional calibration method is explained. To get the improved accuracy of 2-dimensional calibration result, the 3-dimensional calibration set an imaginary plane and executes the calibration in various 3-dimensional spaces. To show the efficiency of 3-dimensional calibration, we analyze the experimental result. It also introduces various using methods and information that can be obtained through the device.

• 한국해양학회지
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• v.14 no.2
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• pp.78-85
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• 1979

Korea has not any fixed station for Radio Navigation systems yet. In some part of the Korean Sea, however, Japanese stations can be utilized for the Radio Navigation. 3 Decca chains were proposed to install the Decca Navigation network for Korea. Only for the coverage area, 1 Decca chain is sufficient for the sea around Korea instead of 3 chains. At present, Omega system is the most recommendable for the positioning in the farther area. In nearshore area, Raydist or Decca Trisponder is is useful for obtaining the position with high accuracy.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.9 no.6
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• pp.1569-1573
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• 2008

This paper describes a development of Ultrasonic NDE software to analyze steam generator of nuclear power plant. The developed software includes classical analysis method such as A, B, C and D-scan images. And it can analyze the detected internal cracks using 3D image processing method. To do such, we obtain raw data from specimens of real pipeline of power plants, and get the envelope signal using Empirical Mode Decomposition from obtained ultrasonic 1-dimensional data. The reconstructed 3D crack images offer useful information about the location, shape and size of cracks, even if there is no special 2D image analysis technique. The developed analysis software is applied to specimens containing various cracks with known dimensions. The results of application showed that the developed software provided accurate and enhanced 2D images and reconstructed 3D image of cracks.