• Proceedings of the KIEE Conference
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• 2003.07d
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• pp.2372-2374
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• 2003

With 3-D vision measuring, camera calibration is necessary to calculate parameters accurately. Camera calibration was developed widely in two categories. The first establishes reference points in space, and the second uses a grid type frame and statistical method. But, the former has difficulty to setup reference points and the latter has low accuracy. In this paper we present an algorithm for camera calibration using perspective ratio of the grid type frame with different line widths. It can easily estimate camera calibration parameters such as focal length, scale factor, pose, orientations, and distance. But, radial lens distortion is not modeled. The advantage of this algorithm is that it can estimate the distance of the object. Also, the proposed camera calibration method is possible estimate distance in dynamic environment such as autonomous navigation. To validate proposed method, we set up the experiments with a frame on rotator at a distance of 1,2,3,4[m] from camera and rotate the frame from -60 to 60 degrees. Both computer simulation and real data have been used to test the proposed method and very good results have been obtained. We have investigated the distance error affected by scale factor or different line widths and experimentally found an average scale factor that includes the least distance error with each image. It advances camera calibration one more step from static environments to real world such as autonomous land vehicle use.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.46 no.9
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• pp.782-789
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• 2018

Multi-Function Display (MFD) of Korean Utility Helicopter (KUH) displays image information(navigation, flight, topographical and maintenance information) delivered from Mission Computer (MC) during flight operation. The abnormal display of MFD such as flickering phenomenon was identified in the system development. It was solved by improving the shielding performance of the DVI cable and changing the DVI cable installation path at the first mass production. However, it was occurred again when the aircraft was operated for one or two years after delivery. It was also identified in the evaluation process of the derivative helicopters. Therefore, a comprehensive review of the aircraft system level has been performed to solve the problem of MFD malfunction at first and then a design improvement plan was derived by improving the DVI cable. In this paper, the causes of MFD anomalies are analyzed and also the process of design improvement are summarized. The validity of the improvement has been verified through the DVI cable assembly comparison test, SIL/ground/flight test.

• Journal of Biomedical Engineering Research
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• v.40 no.5
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• pp.206-214
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• 2019

Surgical methods and associated precision systems have been developed, but surgical procedures that require precise location and fine manipulation of the lesion remain a limitation. The combination of precision robot manipulation technology and 3D medical image navigation technology overcomes the limitations of minimally invasive surgery (MIS) and enables a more stable and successful operation. Surgical robots are surgical robots such as da Vince, and surgical robots using industrial robotic arms. There are various developments and researches of medical robots. In recent medical robot development, a new type of surgical robot based on an industrial robot arm capable of easily replacing the end effector according to the user's needs is being actively developed at home and abroad. Therefore, in this study, we developed safety and performance evaluation guideline for micro - surgical robots based on open robot platform using general purpose robot arm to help quality control of the medical device.

• Journal of IKEEE
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• v.22 no.4
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• pp.970-977
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• 2018

The autonomous vehicle is based on an advanced driver assistance system (ADAS) consisting of a sensor that collects information about the surrounding environment and a control module that determines the measured data. As interest in autonomous navigation technology grows recently, an easy development framework for ADAS beginners and learners is needed. However, existing development and verification methods are based on high performance vehicle simulator, which has drawbacks such as complexity of verification method and high cost. Also, most of the schemes do not provide the sensing data required by the ADAS directly from the simulator, which limits verification reliability. In this paper, we present an interactive ADAS development and verification framework using a 3D vehicle simulator that overcomes the problems of existing methods. ADAS with image recognition based artificial intelligence was implemented as a virtual sensor in a 3D car simulator, and autonomous driving verification was performed in real scenarios.

• The Journal of Korean Institute of Information Technology
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• v.17 no.10
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• pp.57-63
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• 2019

Motion errors which are caused by several reasons, non-ideal path, errors of navigation systems, and radar system errors, have to be corrected. Motion compensation methods can compensate the motion error, but not exactly. To correct these residual errors, several autofocus methods are invented. A popular method is phase gradient autofocus (PGA). PGA does not assume specific circumstances, such as isolated point targets and shapes of errors. PGA is an iterative and adaptive method, so that the processing time is the main problem for the real time processing. In this paper, the improved method to select targets for PGA is proposed to reduce processing time. The variances of image pixels are used to select targets with high SNR. The processing of PGA with these targets diminishes the processing time and iterations effectively. The processed results with real radar data, obtained by flight tests, show that the proposed method compensates errors well, and reduce working time.

• Journal of People, Plants, and Environment
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• v.24 no.4
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• pp.441-450
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• 2021

Background and objective: The purpose of study is to analyze the three-dimensional (3D) structure by creating a 3D model for green spaces in a park using unmanned aerial vehicle (UAV) images. Methods: After producing a digital surface model (DSM) and a digital terrain model (DTM) using UAV images taken in Mureung Park in Chuncheon-si, we generated a digital tree height model (DHM). In addition, we used the mean shift algorithm to test the classification accuracy, and obtain accurate tree height and volume measures through field survey. Results: Most of the tree species planted in Mureung Park were Pinus koraiensis, followed by Pinus densiflora, and Zelkova serrata, and most of the shrubs planted were Rhododendron yedoense, followed by Buxus microphylla, and Spiraea prunifolia. The average height of trees measured at the site was 7.8 m, and the average height estimated by the model was 7.5 m, showing a difference of about 0.3 m. As a result of the t-test, there was no significant difference between height values of the field survey data and the model. The estimated green coverage and volume of the study site using the UAV were 5,019 m² and 14,897 m³, respectively, and the green coverage and volume measured through the field survey were 6,339 m² and 17,167 m³. It was analyzed that the green coverage showed a difference of about 21% and the volume showed a difference of about 13%. Conclusion: The UAV equipped with RTK (Real-Time Kinematic) and GNSS (Global Navigation Satellite System) modules used in this study could collect information on tree height, green coverage, and volume with relatively high accuracy within a short period of time. This could serve as an alternative to overcome the limitations of time and cost in previous field surveys using remote sensing techniques.

• International Journal of Computer Science & Network Security
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• v.22 no.3
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• pp.135-140
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• 2022

Scientific and technological progress is also fundamental to the evolving merchant shipping industry, both in terms of the size and speed of modern ships and in the level of their technical capabilities. While the freight performance of ships is growing, the number of crew on board is steadily decreasing, as more work processes are being automated through the implementation of information technologies, including ship management systems. Although there have been repeated appeals from international maritime organizations to focus on building effective maritime security defenses against cyber attacks, the problems have remained unresolved. Owners of shipping companies do not disclose information about cyberattack attempts or incidents against them due to fear of commercial losses or consequences, such as loss of image, customer and insurance claims, and investigations by independent international organizations and government agencies. Issues of cybersecurity of control systems in the world today have gained importance, due to the fact that existing threats concern not only the security of technical means and devices, but also issues of environmental safety and safety of life at sea. The article examines the implementation of cyber risk management in the shipping industry, providing recommendations for the safe ship operation and its systems in order to improve vulnerability to external threats related to cyberattacks, and to ensure the safety and security of such a technical object as a seagoing ship.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2022.05a
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• pp.465-468
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• 2022

The incidence of traffic accidents is increasing every year, and Korea is among the top OECD countries. In order to improve this, various road traffic laws are being implemented, and various traffic control methods using equipment such as unmanned speed cameras and traffic control cameras are being applied. However, as drivers avoid crackdowns by detecting the location of traffic control cameras in advance through navigation, a mobile crackdown system that can be cracked down is needed, and research is needed to increase the recognition rate of vehicle license plates on the side of the road for accurate crackdown. This paper proposes a method to improve the vehicle number recognition rate on the road side by applying a gradient correction algorithm using image processing. In addition, custom data learning was conducted using a CNN-based YOLO algorithm to improve character recognition accuracy. It is expected that the algorithm can be used for mobile traffic control cameras without restrictions on the installation location.

• Imaging Science in Dentistry
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• v.53 no.1
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• pp.77-82
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• 2023

Purpose: This study evaluated anatomical variations in the root canals of the lower premolars and molars in a Brazilian sub-population using cone-beam computed tomography (CBCT). Materials and Methods: In total, 121 CBCT images of patients were selected from a database. All images contained lower first and second premolars and molars on both sides of the arch, fully developed roots, and no treatment, resorption, or calcifications. In each image, the root canals of the lower premolars and molars were evaluated according to the Vertucci classification in On-Demand 3D software in the multiplanar reconstruction with dynamic navigation. Twenty-five percent of the images were re-assessed to analyze intraobserver confidence with the kappa test. Data were statistically evaluated with linear regression to evaluate the correlations of anatomic variations with age and sex, and the Wilcoxon test to analyze the laterality of variations, with a significance level of 5%. Results: The intraobserver agreement (0.94) was excellent. In general, the root canals of lower premolars and molars showed a higher prevalence of type I than other Vertucci classification types, followed by type V in premolars and type II in molars. When the molar roots were evaluated separately, type II was more frequent in mesial roots and type I in distal roots. Although age showed no correlations with the results, sex and laterality showed correlations with tooth 45 and the lower second premolars, respectively. Conclusion: The lower premolars and molars of a Brazilian sub-population showed a wide range of root canal anatomic variations.

• Journal of Service Research and Studies
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• v.12 no.1
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• pp.25-35
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• 2022

Covid-19, of which the first patient in Korea occurred in January 2020, has affected various fields. Of these, the tourism sector might havebeen hit the hardest. In particular, since tourism-based industrial structure forms the basis of the region, Gangwon-province, and the tourism industry is the main source of income for small businesses and small enterprises, the damage is great. To check the situation and extent of such damage, targeting the Chuncheon region, where public access is the most convenient among the Gangwon regions, one-day tours are possible using public transportation from Seoul and the metropolitan area, with a general image that low expense tourism is recognized as possible, this study conducted empirical analysis through data analysis. For this, the general status of the region was checked based on the visitor data of Chuncheon city provided by the tourist information system, and to check the levels ofinterest in 2019, before Covid-19, and in 2020, after Covid-19, by comparing keywords collected from the web service sometrend of Vibe Company Inc., a company specializing in keyword collection, with SK Telecom's T-map search site data, which in parallel provides in-vehicle navigation service and communication service, this study analyzed the general regional image of Chuncheon-city. In addition, by comparing data from two years by developing a tourism popularity index applying keywords and T-map search site data, this study examined how much the Covid-19 situation affected the level of interest of visitors to the Chuncheon area leading to actual visits using a data analysis approach. According to the results of big data analysis applying the tourism popularity index after designing the data mart, this study confirmed that the effect of the Covid-19 situation on tourism popularity in Chuncheon-city, Gangwon-provincewas not significant, and confirmed the image of tourist destinations based on the regional characteristics of the region. It is hoped that the results of this research and analysis can be used as useful reference data for tourism economic policy making.