• Journal of the Korea institute for structural maintenance and inspection
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• v.22 no.2
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• pp.115-123
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• 2018

In a long-span bridge, the cables are important elements that support the load of the bridge. Accordingly, the cable tension is a very important variable in evaluating the health and safety of the bridge. The most popular methods of estimating the cable tensions are the direct method, which directly measures the cable stresses using load cells, hydraulic jacking devices, etc., and the vibration method, which inverses the tensions using the cable shapes and the measured dynamic characteristics. Studies on the use of the electromagnetic (EM) sensor, which detects the magnetic field variations caused by the change in the stress of the steel in the cable, are increasing. In this study, the lift-off test, the EM sensor, and the vibration method (Vision-based System and Accelerometer) were used to measure cable tension, and their results were compared and analyzed.

• Journal of the Korea Society for Simulation
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• v.32 no.3
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• pp.1-8
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• 2023

Modeling of artificial targets in Synthetic Aperture radar (SAR) mainly simulates radar signals reflected from the faces and edges of the 3D Computer Aided Design (CAD) model with a ray-tracing method, and modeling of the clutter on the Earth's surface uses a method of distinguishing types with similar distribution characteristics through statistical analysis of the SAR image itself. In this paper, man-made targets on the surface and background clutter on the terrain are integrated and made into a three-dimensional (3D) point cloud scatterer model, and SAR image were created through computational signal processing. The results of the SAR Stripmap image generation of the actual automobile based SAR radar system and the results analyzed using EM modeling or statistical distribution models are compared with this 3D point cloud scatterer model. The modeling target is selected as an bridge because it has the characteristic of having both water surface and ground terrain around the bridge and is also a target of great interest in both military and civilian use.

• Journal of Biomedical Engineering Research
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• v.19 no.5
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• pp.469-476
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• 1998

In the case of acquisition and displaying medical Images such as ultrasonography and endoscopy on VGA monitor of PC system, image degradation of tear-drop appears through scan conversion. In this study, we compare several methods which can solve this degradation and implement the hardware system that resolves this problem in real-time with PC. It is possible to represent high quality image display and real-time processing and acquisition with specific de-interlacing device and PCI bridge on our hardware system. Image quality is improved remarkably on our hardware system. It is implemented as PC-based system, so acquiring, saving images and describing text comment on those images and PACS networking can be easily implemented.metabolism. All images were spatially normalized to MNI standard PET template and smoothed with 16mm FWHM Gaussian kernel using SPM96. Mean count in cerebral region was normalized. The VOls for 34 cerebral regions were previously defined on the standard template and 17 different counts of mirrored regions to hemispheric midline were extracted from spatially normalized images. A three-layer feed-forward error back-propagation neural network classifier with 7 input nodes and 3 output nodes was used. The network was trained to interpret metabolic patterns and produce identical diagnoses with those of expert viewers. The performance of the neural network was optimized by testing with 5~40 nodes in hidden layer. Randomly selected 40 images from each group were used to train the network and the remainders were used to test the learned network. The optimized neural network gave a maximum agreement rate of 80.3% with expert viewers. It used 20 hidden nodes and was trained for 1508 epochs. Also, neural network gave agreement rates of 75~80% with 10 or 30 nodes in hidden layer. We conclude that artificial neural network performed as well as human experts and could be potentially useful as clinical decision support tool for the localization of epileptogenic zones.

• Proceedings of the Korean Information Science Society Conference
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• 2004.10c
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• pp.76-78
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• 2004

근래에 이르러 Digital Photo에 대한 사용자들의 수요가 늘어나면서 DSC이나 Camera Phone으로부터 Photo용 Printer로의 Printing Solution 개발에 대한 요구가 증가하고 있다. 2003년에 미국과 일본의 회사들이 이런 용도로 PictBridge를 개발하였다. 이것은 Image File의 전송에 대한 것인데, 최근에 이르러 양질의 프린팅 서비스 제공을 위하여 XHTML을 전송하는 방식에 대한 연구가 진행 중이다. 본 논문은 Pictsridge 상에 HXHTML script을 전송하는 방식에 대한 내용을 담고 있다.

• The Journal of the Korean dental association
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• v.52 no.6
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• pp.354-362
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• 2014

With the development of digital dentistry, various intra-oral scanners which acquire intraoral image without conventional impression taking and stone pouring steps have been introduced. Fixed dental prostheses such as inlay, onlay, crown, and bridge fabricated by CAD/CAM technique combined with digital impressions is getting popular due to the recent rapid progress of digital impression taking system. In comparison with traditional prosthetic procedure, the advantages of intraoral image acquiring and CAD/CAM technique are as follows; the omission of conventional impression materials, reduced workflow step, and increased efficiency by online communication with clinic and laboratory. This review article covers some opinions about the suitable scanning procedures for the various prosthodontic treatments and the utilization of digital intraoral scanner and CAD/CAM system.

• Journal of the Korean Society of Industry Convergence
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• v.26 no.2_2
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• pp.265-272
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• 2023

In this paper, we directly implemented the Line Tracer ROS package that can detect and follow lines drawn on the map on Gazebo, an open-source that is widely used in autonomous driving research. For line detection, the cv_bridge package was used to enable OpenCV's image processing tools, and parameters such as robot speed, line color and ground material could be changed. In addition, proportional (P) and PID controls could be implemented using the color centroid obtained through image processing. Through this approach, the effect of proportional and differential coefficients on the robot's line tracer motion could be analyzed effectively. In addition, by displaying robot simulation results using various tools of ROS, an efficient development for control nodes could be established in ROS.

• Proceedings of the KSR Conference
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• 2006.11b
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• pp.689-694
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• 2006

Wireless LAN is getting more popularity and plays a main role in electronic and telecommunication field. Wireless LAN is more convenient than wired LAN when mobility is required, and are sometimes the only feasible choice. Wireless LAN can also pose a significant security risk when not properly installed and maintained. Thus, this paper studies real-time message transmission using existing mobile telecommunication network and describes considerations and procedures when introducing wireless LAN concept and wireless LAN systems. It also studies integrated wired and wireless networking including wireless LAN bridge and AP technology of International Organization for Standardization, and especially real-time dynamic image data transmission in a moving train.

• Journal of the Korea institute for structural maintenance and inspection
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• v.27 no.2
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• pp.58-66
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• 2023

In this study, cable tension was measured using the vibration method, and a vision-based system was applied as a sensor to measure the displacement response of a cable in a non-contact method. In the vision-based system, the camera is installed in a location that considers the target structure and the field of view of the camera. However, it can be difficult to recognize the control points required to measure the displacement response of a structure as the target structure and other structures such as vehicles may be included in the image at the intended installation location. In this study, a distorted image including a vehicle shows inaccurate results in image analysis due to the installation position of the vision-based system. Accordingly, the image including the vehicle was eliminated by calculating the similarity between the two images. To verify the validity of the method of estimating the cable tension of cable-stayed bridges using the proposed method, the vibration method was applied to cable-stayed bridges in service to measure the tension.

• Smart Structures and Systems
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• v.24 no.5
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• pp.607-616
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• 2019

The video deflectometer based on digital image correlation is a non-contacting optical measurement method which has become a useful tool for characterization of the vertical deflections of large structures. In this study, a novel imaging model has been established which considers the variations of pitch angles in the full image. The new model allows deflection measurement at a wide working distance with high accuracy. A monocular video deflectometer has been accordingly developed with an inclination sensor, which facilitates dynamic determination of the orientations and rotation of the optical axis of the camera. This layout has advantages over the video deflectometers based on theodolites with respect to convenience. Experiments have been presented to show the accuracy of the new imaging model and the performance of the monocular video deflectometer in outdoor applications. Finally, this equipment has been applied to the measurement of the vertical deflection of Yingwuzhou Yangtze River Bridge in real time at a distance of hundreds of meters. The results show good agreement with the embedded GPS outputs.

• Journal of Digital Contents Society
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• v.18 no.6
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• pp.1041-1047
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• 2017

There are many methods for surveying the status of a road, and the use of unmanned aerial vehicle (UAV) photo is one such method. When the UAV images are too large to be processed and suspected to be redundant, a texture extraction technique is used to transform the data into a reduced set of feature representations. This is an important task in 3D simulation using UAV images because a huge amount of data can be inputted. This paper presents a texture extraction method from UAV images to obtain high-resolution images of bridges. The proposed method is in three steps: firstly, we use the 3D bridge model from the V-World database; secondly, textures are extracted from oriented UAV images; and finally, the extracted textures from each image are blended. The result of our study can be used to update V-World textures to a high-resolution image.