• 한국항만학회지
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• 제15권1호
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• pp.87-97
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• 2001

The calculation of earthwork plays a major role in plan or design of many civil engineering projects, and thus it has become very important to advanced the accuracy of earthwork calculation. Current method used for estimating the volume of pit excavation assumes that the ground profile between the grid points is linear(trapezoidal rule), or nonlinear(simpson's formulas). In this paper the spot height method, least square method, and chamber formulas, Chen and Lin method are compared with the volumes of the pits in these examples. As a result of this study, algorithm of chen and Lin me쇙 by spline method should provide a better accuracy than the spot height method, least square method, chamber formulas. The Chen and Lin formulas can be used for estimating the excavation volume of a pit divide into a grid with unequal intervals. From the characteristics of the cubic spline polynomial, the modeling curve of the Chen and Lin method is smooth and matches the ground profile well. Generally speaking, the nonlinear profile formulas provide better accuracy than the linear profile formulas. The mathematical model mentioned make an offer maximum accuracy in estimating the volume of a pit excavation.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2003년도 춘계학술대회 논문집
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• pp.1824-1827
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• 2003

The sheet metal shearing process is normally used in the precision elements such as semi-conductor components. In precision elements, burrs usually reduce the quality of machined parts and cause interference, jamming and misalignment during assembly procedures and because of their sharpness, they can be safety hazard to personnel. Furthermore, not only burrs are hard to predict and avoid, but also deburring, the process of removing burrs, is time-consuming and costly. In order to get the burr-free parts, therefore, we developed the precise burr measuring system using the laser. The laser burr measuring system consists of the laser probe, the photo detector, the achromatic doublet lens, and the rotary ＆ the X-Y table. In previous reports, we used simple vertical measuring method. But, as we used relatively bigger laser spot diameter and had the limited reflection angle, it was difficult to obtain the precise measuring results. So called, the spot size effect makes the profile of burr measured distorted and the burr height measured smaller. By introducing the novel laser measuring method which employing the achromatic lens system and the tilting mechanism, we could make the spot size smaller and get the appropriate beam direction angle. Through the experiments, the accuracy of the developed system is proved. The burr height measured during the punching process can be used for automatic deburring and in-situ aligning.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2005년도 Proceedings of ISRS 2005
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• pp.667-670
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• 2005

Ground control points(GCPs) can be extracted from SAR data given precise orbit for DTM generation using optic images and other SAR data. In this study, we extract GCPs from ERS SAR data and SRTM DEM. Although it is very difficult to identify GCPs in ERS SAR image, the geometry of optic image and other SAR data are able to be corrected and more precise DTM can be constructed from stereo optic images. Twenty GCPs were obtained from the ERS SAR data with precise Delft orbit information. After the correction was applied, the mean values of planimetric distance errors of the GCPs were 3.7m, 12.1 and -0.8m with standard deviations of 19.9m, 18.1, and 7.8m in geocentric X, Y, and Z coordinates, respectively. The geometries of SPOT stereo pair were corrected by 13 GCPs, and r.m.s. errors were 405m, 705m and 8.6m in northing, easting and height direction, respectively. And the geometries of RADARS AT stereo pair were corrected by 12 GCPs, and r.m.s. errors were 804m, 7.9m and 6.9m in northing, easting and height direction, respectively. DTMs, through a method of area based matching with pyramid images, were generated by SPOT stereo images and RADARS AT stereo images. Comparison between points of the obtained DTMs and points estimated from a national 1 :5,000 digital map was performed. For DTM by SPOT stereo images, the mean values of distance errors in northing, easting and height direction were respectively -7.6m, 9.6m and -3.1m with standard deviations of 9.1m, 12.0m and 9.1m. For DTM by RADARSAT stereo images, the mean values of distance errors in northing, easting and height direction were respectively -7.6m, 9.6m and -3.1m with standard deviations of 9.1m, 12.0m and 9.1m. These results met the accuracy of DTED level 2

• Journal of Information Processing Systems
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• 제19권6호
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• pp.791-802
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• 2023

The manual inspection of photovoltaic (PV) panels to meet the requirements of inspection work for large-scale PV power plants is challenging. We present a hot spot detection and positioning method to detect hot spots in batches and locate their latitudes and longitudes. First, a network based on the YOLOv3 architecture was utilized to identify hot spots. The innovation is to modify the RU_1 unit in the YOLOv3 model for hot spot detection in the far field of view and add a neural network residual unit for fusion. In addition, because of the misidentification problem in the infrared images of the solar PV panels, the DeepLab v3+ model was adopted to segment the PV panels to filter out the misidentification caused by bright spots on the ground. Finally, the latitude and longitude of the hot spot are calculated according to the geometric positioning method utilizing known information such as the drone's yaw angle, shooting height, and lens field-of-view. The experimental results indicate that the hot spot recognition rate accuracy is above 98%. When keeping the drone 25 m off the ground, the hot spot positioning error is at the decimeter level.

• 한국공간정보시스템학회:학술대회논문집
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• 한국공간정보시스템학회 2000년도 학술회의 논문집 3권2호
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• pp.67-76
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• 2000

위성영상을 이용하여 지형도를 제작하는 새로운 방법으로 레이다 간섭기법이 활발히 연구되고 있다. 레이다 간섭기법은 같은 지역에 대한 두 장의 SAR 영상을 이용하여 고도값을 추출하는 방법으로, 기존의 SPOT과 같은 광학영상에 비하여 날씨나 시간의 제약을 받지 않고 지형정보를 얻을 수 있다는 장점을 가지고 있다. 그러나 레이다 간섭기법을 이용하여 고도값을 추출하는 방법은 처리과정이 복잡하고 기복이 심한 지역에서의 수직위치 정확도가 떨어진다는 단점을 가지고 있다. 본 연구에서 ERS-1과 ERS-2의 tandem 모드 SAR 영상을 사용하여 수치표고모형을 작성한 후 14개의 지상기준점에 대한 수직위치 정확도를 분석한 결과 14.06m의 오차를 보였다. 그러나 항공탑재레이다 시스템의 영상을 사용하여 수치표고 모형을 제작하면 $2{\sim}5m$의 수직위치 정확도를 얻을 수 있으므로 1/10,000이나 1/25,000 축척 지형도의 수정, 갱신에 활용할 수 있으리라 기대된다.

• 대한토목학회논문집
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• 제11권4호
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• pp.163-170
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• 1991

SPOT 위성영상을 이용한 3차원 위치결정에는 해석적사진측량과 수치적사진 측량방법에서의 번들조정이 적용되며, 이를 위해서는 정밀한 상좌표관측과 정확한 지상기준점좌표가 요구된다. 본 연구에서는 지상측량성과의 비교하여 축척에 따른 지형도의 디지타이징된 평면좌표 정확도와 보간된 높이좌표 정확도를 분석하였고, 또한 지상기준점좌표의 획득방법 및 SPOT 영상자료의 형태를 조합하여 번들조정으로 결정된 3차원좌표의 정확도을 비교 분석하였다.

• Spatial Information Research
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• 제9권1호
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• pp.1-13
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• 2001

위성영상을 이용하여 지형도를 제작하는 새로운 방법으로 레이다 간섭기법에 관한 연구가 활발히 진행되고 있다. 레이다 간섭기법은 동일한 지역을 촬영한 두 장의 SAR 영상의 위상정보를 이용하여 표고값을 추출하는 기법으로, 기존의 SPOT과 같은 광학영상에 비하여 날씨나 시간의 제약을 받지 않고 지형정보를 얻을 수 있다는 장점을 가지고 있다. 즉, 영상취득의 유연성이 뛰어나며 광범위한 면적에 대하여 저렴한 표고데이터 추출이 가능하여 GIS에서의 활용 가능성 또한 밝다고 할 수 있다. 그러나 레이다 간섭기법은 SAR 시스템에 따라 발생하는 기하학적 왜곡으로 인해 일부지역에 대해서는 위상불구속화 알고리즘에 따라 표고값이 잘못 추정되거나 아예 그값을 얻지 못하는 단점을 가지고 있다. 본 연구에서 사용한 ERS 텐덤자료의 경우에는 산악지형에서의 수직위치 정확도가 가장 부정확했으며, 기하학적 왜곡으로는 ERS 위성의 짧은 입사각으로 인한 layover 현상이 주로 발행하였다. 위상불고속화 기법별로는 경로추적방식 알고리즘을 사용했을 경우, 산출된 표고값의 정확도는 최소제곱방식을 수행했을 경우보다 2∼5m 가량 우수하였으나 기하학적 왜곡이 발생한 지역에서의 데이터를 얻지 못하는 결과를 보였다. 이 지역에 대하여 고도민감도를 이용하여 표고값을 추정한 결과 경로추적방식의 정확도를 유지하면서 전체 영상에 대하여 표고값을 갖는 DEM을 제작할 수 있었다.

• 소성∙가공
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• 제13권4호
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• pp.342-349
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• 2004

The form-joining process (or clinching) uses a set of die and punch to impose the plastic deformation-induced geometric constraint on a sheet metal pair. The joining strength from the process ranges 50-70 percent of that of the resistance spot welding. In this paper, a new form-joining process with the aid of an adhesive is proposed in which an epoxy adhesive is applied to a sheet metal pair, and before it cures the pair is clinched to cause the geometric constraint in the form of a protrusion. In order to reduce the forming load and the height of protrusions, a new die and punch set with a very small clearance is devised to reduce the depth of drawing and the forming load. Taguchi method is employed to find the optimal values of design parameters. To implement each case of the orthogonal array, the finite element method is used. The experiments show that in the tensile-shear test, the bonding strength of the new form-joining process with an epoxy adhesive is approximately the same as that of the resistance spot welding; and in comparison with the other two form-joining processes with an epoxy adhesive, the height of protrusions is reduced by more than 65 percent and the forming load by 50 percent.

• 비파괴검사학회지
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• 제7권1호
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• pp.42-50
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• 1987

Most of significant defects in the pressure boundaries of nuclear power plant we re dispositioned to be monitored periodically every inservice inspection. Due to the difficulty of the defect sizing during operation, it is necessary to develope the continuous flaw monitoring techniques. The Tip Diffraction method, specifically speaking, spot seems to be suitable for flaw monitoring. The optimum conditions of selecting the transducer were 3.5 MHz and 45-57 degree according to compatibility with the defect height. The effective calculation of the defect height was to assume the fact that the incident beam is parallel. This method would be supplemented to ASME method about the defect characterization for the surface flaw.

• 한국측량학회지
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• 제18권3호
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• pp.305-313
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• 2000

건설시공현장에서 토공량결정은 전체공사비 중에 큰 비중을 차지하므로 정확한 계산방법이 있어야 한다 토공량을 계산하는 현행방법은 격자점사이의 횡단면의 간격을 선형 (사다리꼴법칙)이나 비선형(심프슨법칙)으로 가정한다. 일반적으로 비선형법칙이 선형법칙보다 더 정확한 것으로 나타나 있다. 그러나 앞에서 언급된 모든 방법은 예리한 코너부분이나 두점 사이의 갑작스런 지형변화에 대처할 수 없는 결점을 내포하고 있다. 본 연구에서는 일정 구역의 양방향에 splin법을 적용한 식을 구하였으며, 점고법, Chamber법, 그리고 Chen과 Lin법을 서로 비교하였다. 그 결과 제시된 방법은 기존의 방법들 보다 더 정확하였다. 또한, 제시된 수학적모델법은 현행식들의 정확도 평가에 기준이 된다.