• Journal of the Korea institute for structural maintenance and inspection
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• v.26 no.5
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• pp.30-42
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• 2022

Due to the increase in construction of tunnels, the burdens of maintenance works for tunnel structures have been increasing in Korea. In addition, the increase of traffic volume and aging of materials also threatens the safety of tunnel facilities, therefore, maintenance costs are expected to increase significantly in the future. Accordingly, automated condition assessment technologies like image-based tunnel scanning system for inspection and diagnosis of tunnel facilities have been proposed. For image-based tunnel scanning system, it is key to create a planar image through stitching of multiple images captured by tunnel scanning system. In this study, performance of feature-based stitching algorithms suitable for stitching tunnel scanning images was evaluated. In order to find a suitable algorithm SIFT, ORB, and BRISK are compared. The performance of the proposed algorithm was determined by the number of feature extraction, calculation speed, accuracy of feature matching, and image stitching result. As for stitching performance, SIFT algorithm was the best in all parts of tunnel image. ORB and BRISK also showed satisfactory performance and short calculation time. SIFT can be used to generate precise planar images. ORB and BRISK also showed satisfactory stitching results, confirming the possibility of being used when real-time stitching is required.

• Journal of Korean Tunnelling and Underground Space Association
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• v.25 no.3
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• pp.245-259
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• 2023

The purpose of this paper is to examine the most recent tunnel scanning systems to obtain insights for the development of non-contact mobile inspection system. Tunnel scanning systems are mostly being developed by adapting two main technologies, namely laser scanning and image scanning systems. Laser scanning system has the advantage of accurately recreating the geometric characteristics of tunnel linings from point cloud. On the other hand, image scanning system employs computer vision to effortlessly identify damage, such as fine cracks and leaks on the tunnel lining surface. The analysis suggests that image scanning system is more suitable for detecting damage on tunnel linings. A camera-based tunnel scanning system under development should include components such as lighting, data storage, power supply, and image-capturing controller synchronized with vehicle speed.

• Journal of the Korea Institute of Building Construction
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• v.16 no.6
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• pp.579-585
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• 2016

3D laser scanning can be used for scanning the freeform surface and building a model from which the measurements could be taken, in order to solve the difficulty with getting access to the exact freeform shape and position data of the complex building envelope. The shape making process using 3D scanning is as follows: point cloud, mesh surface segmentation, NURBS(Non-Uniform Rational B-spline) surface generation, and parametric solid model generation. In this research, we review previous studies, reverse engineering notion, importance of reverse engineering usage for freeform envelope, and previous cases in order to identify the detail reverse engineering process for prefabrication and construction of freeform panels using 3D laser scanning technology. Therefore, the purpose of this research is to present a basic information which should be considered during design and construction phase and improve quality and constructibility of freeform building by analyzing the reverse engineering process and case study for prefabrication and construction of freeform panels using 3D laser scanning. The research results will enable 3D shape engineering and design parameterization using reverse engineering to be used in various construction projects.

• 프린팅코리아
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• s.5
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• pp.86-91
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• 2002

디지털 인쇄 테크놀로지가 소비자와 인쇄업계의 관계를 바꾸어 놓았다. 1960년대 시작된 컴퓨터 조판, 1970년대 중반 컬러 스캐닝 혁명을 거쳐 오늘날 완벽한 컬러를 구현하는 DTP, 그래픽 기술들은 급격한 변화의 흐름 속에 있다. 이러한 변화는 강화될 것으로 보인다. 스캐너, 디지털카메라 등 이미지 획득 장비의 값이 급격히 하락하고 이미지 구현 소프트웨어의 구입과 작동 비용이 감소하면서 프린터 업자들이 갖고 있었던 파워가 출판업자, 에이전시, 디자이너, 기업의 디자인 부서 등 창조적 존재들에게로 이전되었다.

• Journal of Advanced Navigation Technology
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• v.12 no.6
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• pp.659-665
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• 2008

We demonstrate experimentally that the method of Two-pupil optical scanning technique with PAL-spatial light modulator is capable of performing real-time joint transform correlation(JTC) optical system. Optical addressing is achieved by the use of a photosensitive layer of $\alpha$ - Si which controls the electric field across the liquid crystal The demonstrated technique is based on two-pupil optical heterodyne scanning. The method is independent of a spatial light modulator (SLM) in the Fourier plane. We develop the theory of the technique and evaluate a performance of the method by experimentally estimating the correlation between the target image and the reference image.

• Journal of Digital Contents Society
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• v.16 no.1
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• pp.113-121
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• 2015

Artifact pattern representation of a method using the digital technology is largely are two digital rubbing technique and digital contrast technique. Digital rubbing technique is clearly with the naked eye to see the original prestigious and difficult to build a digital rubbing data patterns by scanning a prestigious and patterns carved into the artifacts in three dimensions without compromising the circle to represent the three-dimensional effect by contrast it to the objective value refers to a technique that can be represented in digital. Digital contrast technique can not be calculated if the depth information of the object due to the glassy film of artefacts in a three-dimensional surface scanning and the application of this technique refers to a realistic image mapped digital technique for generating digital image contrast. Digital rubbing technique is mainly useful to express the most prestigious and patterns expressed in pottery or tile and stone monument, etc. engraved or embossed, digital contrast techniques can be used effectively to artifacts such as magnetic or glass can not be applied to the digital rubbing technique.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.8
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• pp.1-7
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• 2019

When using conventional 3D image scanning methods, it is common for image scanning to be done manually, which is labor-intensive. Scanning a space made up of complicated equipment or scanning a narrow space that is difficult for the user to enter, is problematic, resulting in quality degradation due to the presence of shadow areas. This paper proposes a method to scan an image using a rover equipped with a scanner in areas where it is difficult for a person to enter. To control the scan path precisely, the 3D image remote scan automation method based on the rover move rule definition is described. Through the study, the user can automate the 3D scan plan in a desired manner by defining the rover scan path as the rule base.

• Journal of Digital Contents Society
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• v.16 no.5
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• pp.835-847
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• 2015

Photo scanning can create point cloud and polygon models like 3D scanners bringing an object into the 3 dimensional world by combining several sheets of photographic information. The created data give us information about planes and sectional forms required for a 2 dimensional survey as well as 3 dimensional figures of buried cultural property. It requires a lot of time to record buried cultural property in the field, however, the photo scanning technique does not need additional equipment and manpower so the work may begin immediately while the property is protected. Moreover, it reduces financial burdens as it creates 3 dimensional data using images acquired by photography but provides the optimal condition to check 3 dimensional information quickly and easily.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.8
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• pp.1759-1764
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• 2012

This paper describes FPGA design and realization using the shading correction algorithm for a CCD scan image enhancement. The shading algorithm is used by LUT (Look-up Table). The image enhancement results from that the histogram minimum value and maximum with respect to all pixels of the CCD image should be extracted, and the shading LUT is constructed to keep constant histogram with offset data. The output of sensor be converted to corrected LUT image in preprocessing, and the converting system is realized by FPGA to be enabled to operate in real time. The result of the experimentation for the proposed system is showed to take the scanning time 2.4ms below. The system is presented to be based on a low speed processor system to scan enhanced images in real time and be guaranteed to be low cost.

• Journal of the Korean Geotechnical Society
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• v.40 no.1
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• pp.15-28
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• 2024

This paper proposes a method to acquire image data inside tunnel structures and a method to structure the acquired image data. By improving the conditions by which image data are acquired inside the tunnel structure, high-quality image data can be obtained from area type tunnel scanning. To improve the data acquisition conditions, a longitudinal rail of the tunnel can be installed on the tunnel ceiling, and image data of the entire tunnel structure can be acquired by moving the installed rail. This study identified 0.5 mm cracked simulation lines under a distance condition of 20 m at resolutions of 3,840 × 2,160 and 720 × 480 pixels. In addition, the proposed image-data-structuring method could acquire image data in image tile units. Here, the image data of the tunnel can be structured by substituting the application factors (resolution of the acquired image and the tunnel size) into a relationship equation. In an experiment, the image data of a tunnel with a length of 1,000 m and a width of 20 m were obtained with a minimum overlap rate of 0.02% to 8.36% depending on resolution and precision, and the size of the local coordinate system was found to be (14 × 15) to (36 × 34) pixels.