• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2001년도 추계학술대회(한국공작기계학회)
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• pp.85-90
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• 2001

Recent general Press brake has many problems in cutting high accurate products in the progress of industry. Previous hand-operated press brake needs many pre-processing works to adjust bending ang1e and marking-off works to calculate bending length. Also, the hand-operating work makes many geometric errors and has difficulty for variety-mass production. To solve these problems, this paper proposes Computer Numerical Control (CNC) general press brake and development of servo-control system based on database for reduction of geometric errors and pre-processing work time and high accuracy bending work.

• 제어로봇시스템학회논문지
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• 제15권8호
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• pp.772-777
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• 2009

The geometric distortion of image is one of the most important parameters that take effect on the accuracy of optical inspection systems. We propose a new correction method of the image distortion to increase the accuracy of PCB inspection systems. The model-free method is applied to correct the randomly distorted image that cannot be represented by mathematical model. To reduce the correction time of inspection system, we newly propose a grid reduction algorithm that minimize the number of grids by the quad-tree approach. We apply the proposed method to a PCB inspection system, and verify its usefulness through experiments using actual inspection images.

• 대한기계학회논문집A
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• 제21권12호
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• pp.1973-1983
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• 1997

Higher order isoparametric elements are usually used in the finite element analysis because they can represent easily the geometric shape of a complex structure ad can improve the solution quality. When these elements are used, the position of internal nodes affects greatly on the solution accuracy. Decreasing of the accuracy related to the position of internal nodes is due to non-conformal mapping often results in an unstable Jacobian value. This paper, in order to remove this difficulty, suggests a modified shape function which can establish conformal mapping between two coordinate systems. Numerical experiments with the proposed shape function show that a stable solution can be obtained without respect to the position of internal nodes, and offer convenience that one can take arbitrarily the position of internal nodes considering only the geometric shape of element boundaries.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제9권11호
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• pp.4453-4468
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• 2015

This paper investigates optimization-based base station (BS) placement. An optimization model is defined and the BS placement problem is transformed to a lexicographical stratified programming (LSP) model for a given trajectory, according to different accuracy requirements. The feasible region for BS deployment is obtained from the positioning system requirement, which is also solved with signal coverage problem in BS placement. The LSP mathematical model is formulated with the average geometric dilution of precision (GDOP) as the criterion. To achieve an optimization solution, a tolerant factor based complete stratified series approach and grid searching method are utilized to obtain the possible optimal BS placement. Because of the LSP model utilization, the proposed algorithm has wider application scenarios with different accuracy requirements over different trajectory segments. Simulation results demonstrate that the proposed algorithm has better BS placement result than existing approaches for a given trajectory.

• 한국측량학회:학술대회논문집
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• 한국측량학회 2002년도 추계학술발표회 논문집
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• pp.205-208
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• 2002

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 1998년도 Proceedings of International Symposium on Remote Sensing
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• pp.252-256
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• 1998

Accurate mapping of satellite images is one of the most important Parts in many remote sensing applications. Since the position and the attitude of a satellite during image acquisition cannot be determined accurately enough, it is normal to have several hundred meters' ground-mapping errors in the systematically corrected images. The users which require a pixel-level or a sub-pixel level mapping accuracy for high-resolution satellite images must use a number of Ground Control Points (GCPs). In this paper, the performance of two geometric correction algorithms is tested and compared. One is the polynomial warping algorithm which is simple and popular enough to be implemented in most of the commercial satellite image processing software. The other is full camera modelling algorithm using Physical orbit-sensor-Earth geometry which is used in satellite image data receiving, pre-processing and distribution stations. Several criteria were considered for the performance analysis : ultimate correction accuracy, GCP representatibility, number of GCPs required, convergence speed, sensitiveness to inaccurate GCPs, usefulness of the correction results. This paper focuses on the usefulness of the precision correction algorithm for regular image pre-processing operations. This means that not only final correction accuracy but also the number of GCPs and their spatial distribution required for an image correction are important factors. Both correction algorithms were implemented and will be used for the precision correction of KITSAT-3 images.

• 한국측량학회지
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• 제21권2호
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• pp.165-172
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• 2003

IKONOS 위성영상은 지형·지물의 분포 파악 및 추출에 적합하여 많은 분야에서 이를 이용한 연구가 활발히 진행되고 있다. 그러나, IKONOS 위성영상은 3차원 지형정보를 추출할 수 있는 위성센서의 위치와 자세에 대한 정보를 공개하지 않고 있어 영상의 3차원 지형정보 획득을 위해서는 영상에서 제공하는 유일한 자료인 RPC(Rational Polynomial coefficients) 정보를 이용해야만 하는 실정이다. 이에 본 연구에서는 IKONOS 위성영상이 제공하는 RPC 정보를 통해 3차원 지상좌표 추출 알고리즘을 구현하여 프로그램을 개발하였으며, 이를 통한 3차원 지상좌표 추출시 발생하는 오차를 지상기준점 측량성과에 의해 보정하여 지상기준점의 수와 배치에 따른 위성영상의 기하학적 정확도 분석을 수행하므로써 고해상도 위성영상을 이용한 측정정확도 및 효율성을 향상시킬 수 있었다.

• 한국측량학회지
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• 제9권1호
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• pp.83-96
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• 1991

본 연구는 최근 소축척 및 중축척지도 제작과 database 구축등의 활용분야에 효용성이 확대되고 있는 SPOT 위성영상의 3차원 위치결정에 대한 연구로서, 사진필름형태의 SPOT 위성영상에 대해 전처리 수준(level 1AP, 1B)에 따른 기하학적 특성과 정확도에 대해 분석하였다. 본 연구 결과, 전처리 수준에 따른 SPOT위성사진의 기하학적 특성과 각 전처리 수준의 외부표정요소에 대한 최적 다항식 형태 및 유의한 부가매개변수를 결정할 수 있었으며, level 1AP가 level 1B에 비해 기하학적 정밀도와 정화도가 양호하여 정밀한 3차원 위치결정과 지도제작에 적합함을 알 수 있었다.

• 대한원격탐사학회지
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• 제36권4호
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• pp.503-513
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• 2020

This paper presents a method to evaluate denoising filters based on edge locations in their denoised images. Image quality assessment has often been performed by using structural similarity (SSIM). However, SSIM does not provide clearly the geometric accuracy of features in denoised images. Thus, in this paper, a method to localize edge locations with subpixel accuracy based on adaptive weighting of gradients is used for obtaining the subpixel locations of edges in ground truth image, noisy images, and denoised images. Then, this paper proposes a method to evaluate the geometric accuracy of edge locations based on root mean squares error (RMSE) and jaggedness with reference to ground truth locations. Jaggedness is a measure proposed in this study to measure the stability of the distribution of edge locations. Tested denoising filters are anisotropic diffusion (AF), bilateral filter, guided filter, weighted guided filter, weighted mean of patches filter, and smoothing filter (SF). SF is a simple filter that smooths images by applying a Gaussian blurring to a noisy image. Experiments were performed with a set of simulated images and natural images. The experimental results show that AF and SF recovered edge locations more accurately than the other tested filters in terms of SSIM, RMSE, and jaggedness and that SF produced better results than AF in terms of jaggedness.

• 한국측량학회지
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• 제37권2호
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• pp.71-79
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• 2019

Geolocation accuracy is one of the important factors in utilizing all weather available SAR satellite imagery. In this study, an error budget analysis was performed on key variables affecting on geolocation accuracy by generating KOMPSAT-5 simulation data. To perform the analysis, a Range-Doppler model was applied as a geometric model of the SAR imagery. The results show that the geolocation errors in satellite position and velocity are linearly related to the biases in the azimuth and range direction. With 0.03cm/s satellite velocity biases, the simulated errors were up to 0.054 pixels and 0.0047 pixels in the azimuth and range direction, and it implies that the geolocation accuracy is sensitive in the azimuth direction. Moreover, while the clock drift causes a geolocation error in the azimuth direction, a signal delay causes in the range direction. Monte-Carlo simulation analysis was performed to analyze the influence of multiple geometric error sources, and the simulated error was up to 3.02 pixels in the azimuth direction.