• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.20 no.2
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• pp.127-136
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• 2002

DEM(Digital Elevation Model) is used widely in image processing, water resources, construction, GIS, landscape architecture, telecommunication, military operations and other related areas. And it is used especially in producing ortho-photo based on specific DEM and developing 3D GIS database vividly. As LiDAR(Light and Detection And Ranging) system emerged recently, DEM could be developed in urban area more efficiently and more economically, compared to the conventional DEM Production. Traditional method using check points for elevation has tome limitations in structure's height accuracy by LiDAR, because it uses only terrain height. Accordingly after the downtown of Chungju city was selected as a test field in this paper and DEM and digital ortho images was produced by way of LiDar survey, the accuracy was evaluated through analytical plotting map. The result shows that in case of buildings in LiDAR DEM, the accuracy is 0.30 m in X, 0.62 m in Y and RMS is 1.17 m. The difference distribution between DEM and plotting map in range of $\pm$10 cm was 36.2% and $\pm$10 cm $\pm$20 cm was 43.53%. The accuracy of LiDAR in this study meets 1/5,000 which is the regulation for map of NGI(National Geography Institute) and LiDAR can be possibly used in many other applied area.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.6C
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• pp.793-800
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• 2004

In this paper, we propose a new automatic pipe grading algorithm for an efficient management of transmission pipe under the ground. Since the conventional transmission pipe evaluation was conducted by subjective decision made by an individual operator, it was difficult to grade them by means of numerical methods and also hard to realistically construct numerical database system. To solve these problems, we Int obtain some information on the current condition of pipes' sections by shooting laser beam at a regular rate and then apply grading algorithm after complete calculation of minimum diameter of pipe. We use some of preprocessing techniques to reduce noise and also use various color models to consider special conditions of each inner pipe. The measurement of pipes' minimum diameter and decision of grade are performed through a detailed processing stages. By some experimental results performed in the field, we show that over 90 percent of correct grade decisions are made by the proposed algorithm.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.20 no.3
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• pp.891-900
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• 1996

The vision sensor which is based on the optical triangulation theory with the laser as an auxiliary light source can detect not only the seam position but the shape of seam. In this study, a vision sensor using the scanning laser beam was investigated. To design the vision sensor which considers the reflectivity of the sensing object and satisfies the desired resolution and measuring range, the equation of the focused laser beam which has a Gaussian irradiance profile was firstly formulated, Secondly, the image formaing sequence, and thirdly the relation between the displacement in the measuring surface and the displacement in the camera plane was formulated. Therefore, the focused beam diameter in the measuring range could be determined and the influence of the relative location between the laser and camera plane could be estimated. The measuring range and the resolution of the vision sensor which was based on the Scheimpflug's condition could also be calculated. From the results mentioned above a vision sensor was developed, and an adequate calibration technique was proposed. The image processing algorithm which and recognize the center of joint and its shape informaitons was investigated. Using the developed vision sensor and image processing algorithm, the shape informations was investigated. Using the developed vision sensor and image processing algorithm, the shape informations of the vee-, butt- and lap joint were extracted.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.38 no.1
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• pp.43-57
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• 2002

This paper introduces an analysis method to predicting the flow characteristic of flow field around otter board In order to develope a high performance model. In this experiment, it is used a numerical analysis of flow field through CFD(Computational Fluid Dynamic), PIV method in which quantitative, qualitative evaluation is possible. In this experiment, it is used PIV method with flow filed image around otter board in order to analysis of flow characteristic. The result compared flow pattern with analysis result through CFD and also measurement result of lift and drag force coefficient carried out in CWC(Circulating Water Channel). The numerical analysis result is matched well with experiment result of PIV in the research and it is able to verify In the physical aspect. The result is as follows ; (1) It was carried out visibility experiment using laser light sheet, and picture analysis through PIV method in order to analysis fluid field of otter-board. As a result, the tendency of qualitative fluid movement only through the fluid particle's flow could be known. (2) Since PIV analysis result is quantitative, this can be seen in velocity vector distributions, instantaneous streamline contour, and average vorticity distributions through various post processing method. As a result, the change of flow field could be confirmed. (3) At angle of attack 24$^{\circ}$ where It Is shown maximum spreading force coefficient, the analysis result of CFD and PIV had very similar flow pattern. In both case, at the otter-board post edge a little boundary layer separation was seen, but, generally they had a good flow (4) As the result of post processing with velocity vector distributions, instantaneous streamline contour and average vorticity distributions by PIV, boundary layer separation phenomenon started to happen from angle of attack 24$^{\circ}$, and from over angle of attack 28$^{\circ}$, it happen at leading edge side with the width enlarged.

• Proceedings of the Korea Water Resources Association Conference
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• 2009.05a
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• pp.1812-1816
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• 2009

이미지 해석에 의한 유속장 측정방법은 유체역학분야에서 지난 30 여년 동안 많이 활용되어온 속도측정 기법으로 오늘날에는 이를 수공학 분야에서 이를 유량측정 등 수리현상 해석에 활용하려는 시도가 다각적으로 이루어지고 있다. 이에 본 연구에서는 이미지 해석에 의한 유속장 측정방법을 용담댐 시험유역에 적용하여 그의 자연하천에서의 적용성을 검토하고자 한다. 이미지 해석에 의한 유속장 측정방법은 PIV(Particle Image Velocimetry)로 통칭되고 있으며, PIV는 seeding, illumination, recording, 및 image processing의 네 가지 요소로 구성된다. seeding을 위해서 유체를 따라 흐를수 있는 작은 입자를 유체에 첨가한다. 유체를 따라 흐르는 입자들의 선명한 이미지를 얻기 위해서illumination이 필요하다. PIV를 이용하여 흐름을 해석하기 위한 illumination은 일반적으로 이중펄스 레이저가 이용된다. 이렇게 유속장 해석을 하려는 유체에 대하여 seeding 및 illumination이 준비되면 단일노출- 다중 프레임법, 혹은 다중노출-단일 프레임법으로 흐름을 recording을 한다. image processing은 이미지를 다운로드하고, 디지타이징 및 화질향상을 하는 전처리(pre-processing), 상관계수의 산정에 의한 유속 벡터의 결정 및 에러 벡터를 제거하고 유속장을 그래프화하는 후처리(post-processing) 과정으로 구성된다. LSPIV(Large Scale PIV)는 PIV의 기본원리를 근거로 하여 기존의 PIV에 비하여 실험실 내에서의 수리모형실험이나 일반 하천에서의 유속측정과 같은 큰 규모$(4m^2\sim45,000m^2$)의 흐름해석을 할 수 있도록 Fujita et al.(1994)와 Aya et al.(1995)이 확장시킨 것이다. PIV와 비교시 LSPIV의 다른 점은 넓은 흐름 표면적을 포함하기 위하여 촬영시에 카메라의 광축과 흐름 사이의 각도가 PIV에서 이용하는 수직이 아닌 경사각을 이용하였고 이에 따라 발생하는 이미지의 왜곡을 제거하기 위하여 이미지 변환기법을 적용하여 왜곡이 없는 정사촬영 이미지로 변환시킨다. 이후부터는 PIV의 이미지 처리 방법이 적용되어 표면유속을 산정한다. 다만 이미지 변환을 PIV 이미지 처리 전에 하느냐 후에 하느냐에 따라 유속장 해석결과에 차이가 있다. PIV의 네가지 단계를 포함하여 LSPIV의 각 단계를 구분하면, seeding, illumination, recording, image transformation,image processing 및 post-processing의 여섯 단계로 나뉘어진다 (Li, 2002). LSPIV를 적용시 물표면 입자의 Tracing을 위하여 자연하천에서 사용하기에 적합한 환경친화적인 seeding 재료인 Wood Mulch를 사용하여 유속을 측정하였다. 적용지점은 용담댐 상류의 동향수위관측소 지점으로 이 지점은 한국수자원공사의 수자원시험유역이 위치하고 있다. 이미지의 촬영은 가정용 비디오 캠코더 (Sony DCR-PC 350)을 이용하여 두 줄기의 흐름에 대하여 각각 약 5분 동안의 영상을 촬영한후 이중에서 seeding의 분포가 잘 이루어진 약 1분간을 추출한후 이를 이용하여 PIV 분석에 이용하였다. 대체적으로 유속장의 계산이 무난하게 이루어지었으나 비교적 수질 상태가 양호하고, 수심이 낮고, 하상재료가 자갈로 이루어져 있어 비슷한 색상의 seeding 재료를 추적하기 어려운 구간이 발생한 부분에서는 유속의 계산이 정확히 이루어지지 않았다.

• Journal of Korean Society for Geospatial Information Science
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• v.24 no.3
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• pp.49-58
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• 2016

Applications of drone in various fields have been increasing in recent years. Drone has great potential for forest management. Therefore this paper is using drone for forest damage areas. Forest damage areas is divided into caused by anthropogenic and occurs naturally, the possibility of disasters, such as slope sliding, slope failures and landslides, sediment runoff exists. Therefore, this research was to utilize the drone photogrammetry to perform the damage analysis of forest damage areas. Geometrical treatment processing results in Drone Photogrammetry, the plane position error RMSE was ${\pm}0.034m$, the elevation error RMSE was ${\pm}0.017m$. The plane position error of orthophoto RMSE was ${\pm}0.083m$, the elevation error of digital elevation model RMSE was ${\pm}0.085m$. In addition, It was possible to current state analysis of damage in forest damage areas of airborne LiDAR data of before forest damage and drone photogrammetry data of after forest damage. and application of drone photogrammetry for production base data for restoration and design in forest damage areas.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.12 no.2
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• pp.162-169
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• 2019

Non-destructive freshness measurement using spectroscopy has been carried out several times, but research on freshness and freshness has not been conducted. Therefore the purpose of this study is to develop a system for visually measuring and quantifying the air sack inside the egg by non - destructive method. The experimental environment which designed a small chamber was composed of 850nm band of two IR lasers, IR camera and two servo motors to acquire air sack Images. When the air sack volume ratio is 2.9% or less and the density is 0.9800 or more, the Haugh Unit value is 60 or more It was judged to be a fresh egg of a grade B or higher. These results mean, using the weight measurement, nondestructive decision system, and freshness evaluating algorithm. It can be expected to distinguish grade B or more marketable eggs without using destructive methods.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.1
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• pp.323-328
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• 2019

In order to construct 3D geospatial information about the terrain, current measurement using a total station, remote sensing, GNSS(Global Navigation Satellite System) have been used. However, ground survey and GNSS survey have time and economic disadvantages because they have to be surveyed directly in the field. In case of using aerial photographs and satellite images, these methods have the disadvantage that it is difficult to obtain the three-dimensional shape of the terrain. The terrestrial LiDAR can acquire 3D information of X, Y, Z coordinate and shape obtained by scanning innumerable laser pulses at densely spaced intervals on the surface of the object to be observed at high density, and the processing can also be automated. In this study, terrestrial LiDAR was used to analyze slope displacement. Study area slopes were selected and data were acquired using LiDAR in 2016 and 2017. Data processing has been used to generate slope cross section and slope data, and the overlay analysis of the generated data identifies slope displacements within 0.1 m and suggests the possibility of using slope LiDAR on land to manage slopes. If periodic data acquisition and analysis is performed in the future, the method using the terrestrial lidar will contribute to effective risk slope management.

• Conservation Science in Museum
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• v.24
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• pp.55-74
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• 2020

The Sacred Bell of Great King Seongdeok is required digital precision recording of conservation conditions because of corrosion and partial abrasion of its patterns and inscriptions. Therefore, this study performed digital documentation of the bell using four types of scanning and unmanned aerial vehicle (UAV) photogrammetry technologies, and performed the various shape analyses through image processing. The modeling results of terrestrial laser scanning and UAV photogrammetry were merged and utilized as basic material for monitoring earthquake-induced structural deformation because these techniques can construct mutual spatial relationships between the bell and its tower. Additionally, precision scanning at a resolution four to nine times higher than that of the previous study provided highly valuable information, making it possible to visualize the patterns and inscriptions of the bell. Moreover, they are well-suited as basic data for identifying surface conservation conditions. To actively apply three-dimensional scanning results to the conservation of the original bell, the time and position of any changes in shape need to be established by further scans in the short-term. If no change in shape is detected by short-term monitoring, the monitoring should continue in medium- and long-term intervals.

• The Journal of the Korea institute of electronic communication sciences
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• v.9 no.1
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• pp.51-60
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• 2014

In this study, ICT medical service provider's level of knowledge fire fighting safety and methods on coping with fires in the regions of Gwangju and Jeonam Province of Korea were investigated to determine the elements affecting such levels and provide basic information on the manuals for educating how to cope with the fire fighting safety in medical facilities. The data were analyzed using SPSS Win 14.0. The scores of level of knowledge fire fighting safety of ICT medical service provider's were 7.06(10 point scale), and the scores of level of recognizing how to cope with fire fighting safety were 6.61(11 point scale). level of recognizing how to cope with fire fighting safety were significantly different according to gender(t=4.12, p<.001), age(${\chi}^2$=17.24, p<.001), length of career(${\chi}^2$=22.76, p<.001), experience with fire fighting safety education(t=6.10, p<.001), level of subjective knowledge on fire fighting safety(${\chi}^2$=53.83, p<.001). In order to enhance the level of understanding of fire fighting safety and methods of coping by the ICT medical service providers it is found that: self-directed learning through avoiding the education just conveying knowledge by lecture tailored learning for individuals fire fighting education focused on experiencing actual work by developing various contents emphasizing cooperative learning deploying patients by classification systems using simulations and a study on the implementation of digital anti-fire monitoring system with multipoint communication protocol, a design and development of the smoke detection system using infra-red laser for fire detection in the wide space, video based fire detection algorithm using gaussian mixture mode developing an education manual for coping with fire fighting safety through multi learning approach at the medical facilities are required.