• Journal of the Korean Geotechnical Society
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• v.38 no.11
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• pp.137-147
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• 2022

Various geophysical exploration methods are used to determine the exact location of underground utilities, and many studies have been performed to improve the accuracy. This study analyzed the feasibility of exploring underground utilities through a new exploration method using cosmic ray muon. A prototype of a portable muon detector was manufactured by combining a scintillator and a silicon photomultiplier. Further, a calibration operation was performed on the muon count rate. The ground thickness of the ground model was measured using the muon detector prototype, where the value could be estimated with an error of about 3%, close to the actual. In addition, the theoretical basis for tomography analysis technology was analyzed to utilize the muon detector for exploring underground utilities, and a zenith angle correction method was presented. This study revealed that the technology of exploration using muon can analyze density with high resolution and will be used for exploring underground utilities.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.21 no.4
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• pp.114-130
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• 2022

The purpose of this study was to investigate the possibility of increasing the efficiency of disaster relief rescue operations through collaboration among multiple aerial and ground robots. The robots create 2.5D maps, which are merged into a 2.5D map. The 2.5D map can be handled by a low-specification controller of an aerial robot and is suitable for ground robot navigation. For localization of the aerial robot, a six-degree-of-freedom pose recognition method using VIO was applied. To build a 2.5D map, an image conversion technique was employed. In addition, to merge 2.5D maps, an image similarity calculation technique based on the features on a wall was used. Localization and navigation were performed using a ground robot to evaluate the reliability of the 2.5D map. As a result, it was possible to estimate the location with an average and standard error of less than 0.3 m for the place where the 2.5D map was normally built, and there were only four collisions for the obstacle with the smallest volume. Based on the 2.5D map building and map merging system for the aerial robot used in this study, it is expected that disaster response work efficiency can be improved by combining the advantages of heterogeneous robots.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2022.05a
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• pp.571-572
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• 2022

Recently, VR/AR(virtual reality/augmented reality) contents have actively increased, and various services related to VR/AR allow users to experience remote places. Also, Metaverse technologies based on VR/AR generally used to provide content in virtual spaces. In this paper, we present a technique for synthesizing virtual humans after capturing a 360-degree panorama of a remote environment, and analyze the remote environment to identify the location where it can be captured without error, and apply a method of synthesizing virtual humans. According to this paper, it is possible to provide various captured spaces such as industrial plants, medical facilities, and schools as remote communication media.

• The Journal of Korean Institute of Next Generation Computing
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• v.13 no.2
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• pp.35-48
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• 2017

There are many and various devices like sensors, displays, smart phone, etc. in smart environment. And contents can be provided by using these devices. Vast amounts of contents are provided to users, but in most environments, there are no regard for user or some simple elements like location and time are regarded. So there's a limit to provide meaningful contents to users. In this paper, I suggest the contents recommendation system that can recommend contents to users by reasoning context of users, devices and contents. The contents recommendation system suggested in this paper recommend the contents by calculating the user preferences using the situation reasoned with the contextual data acquired from various devices and the user profile received from the user directly. To organize this process, the method on how to model ontology with domain knowledge and how to design and develop the contents recommendation system are discussed in this paper. And an application of the contents recommendation system in Centum City, Busan is introduced. Then, the evaluation methods how the contents recommendation system is evaluated are explained. The evaluation result shows that the mean absolute error is 0.8730, which shows the excellent performance of the proposed contents recommendation system.

• Asia-pacific Journal of Multimedia Services Convergent with Art, Humanities, and Sociology
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• v.5 no.2
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• pp.223-230
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• 2015

Due to the conversion from the existing address system to road name address system, the versatility of the road name address from the public and private sectors is increasing gradually. Therefor, the reliability of the road name address basic map, of the default data is also an urgent need, this means the accuracy of the data. But, road name address basic map is production time due to the use of different map accuracy is to fall, so is also the situation insufficient of utilization. This study Construction of identify each attempt by the road name address basic map and analysis the location accuracy of road name address basic map. As a result, the RMSE of cadastral survey results showed that appears lower than the RMSE of digital map survey results. The judgment can be utilized as the basis for the proposed improvements for the road name address basic map.

• Analytical Science and Technology
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• v.22 no.2
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• pp.141-147
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• 2009

A laser induced breakdown spectroscopy (LIBS) measurement was carried out to derive an optimized measurement condition with a high reproducibility and to grow a plasma sphere to 20 mm high under a 600 mtorr vacuum in order to improve an accuracy of measurement. The measurement of the plasma was taken at a 6.0 mm distance, in the direction of a plasma sphere, from a sample. This location belongs to the outer sphere region in the plasma. The calibration curve of 'Ni' and 'Cu' was acquired by the signal intensity ratio and the atomic ratio for the samples, and linear regression of 'Cu' was $R^2$=0.9886, and the linear regression of 'Ni' was $R^2$=0.9988. The accuracy of LIBS was improved pre-existence as the measurement error of 'Ni' was 0.78%.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.2A
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• pp.215-222
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• 2008

This paper introduces an experimental verification of a tension estimation method based on system identification approach for a double hanger system on a suspension bridge. A laboratory model of such double hanger system has been made for this study. Total nine cases of the vibration tests have been conducted with respect to three levels of applied tension and three cases of the location of clamp. For a set of the collected acceleration response data, modal analysis has been followed in order to extract the natural frequencies and mode shapes of the selected cable systems. For the extracted modal parameters, the existing tension estimation methods based on the string theory and axially loaded beam theory have been firstly applied to estimate the tensile force on the double hanger cable system. Next, the tensile force on cables has been estimated by the system identification approach. It is seen that the errors in the tension estimation using the frequency-based system identification technique are about 3% for all cases while the estimation error using the existing method is up to 53.1%.

• Journal of Advanced Navigation Technology
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• v.25 no.6
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• pp.441-449
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• 2021

With advances in autonomous vehicles, there is a growing demand for more accurate position estimation. Especially, this is a case for a moving robot for the indoor operation which necessitates the higher accuracy in position estimation when the robot is required to execute the task at a predestined location. Thus, a method for improving the position estimation which is applicable to both the fixed and the moving object is proposed. The proposed method exploits the initial position estimation from Bluetooth beacon signals as observation signals. Then, it estimates the gravitational acceleration applied to each axis in an inertial frame coordinate through computing roll and pitch angles and combining them with magnetometer measurements to compute yaw angle. Finally, it refines the control inputs for an object with motion dynamics by computing acceleration on each axis, which is used for improving the performance of Kalman filter. The experimental assessment of the proposed algorithm shows that it improves the position estimation accuracy in comparison to a conventional Kalman filter in terms of average error distance at both the fixed and moving states.

• Journal of Radiation Protection and Research
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• v.48 no.3
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• pp.131-143
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• 2023

Background: This study examined the detection limit of thyroid screening monitoring conducted at the time of the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident in 2011 using a Monte Carlo simulation. Materials and Methods: We calculated the detection limit of a NaI(Tl) survey meter to measure ¹³¹I accumulation in the thyroid gland of children. Mathematical phantoms of 1- and 5-year-old children were developed in the simulation of the Particle and Heavy Ion Transport code System code. Contamination of the body surface with eight radionuclides found after the FDNPP accident was assumed to have been deposited on the neck and shoulder area. Results and Discussion: The detection limit was calculated as a function of ambient dose rate. In the case of 40 Bq/cm² contamination on the body surface of the neck, the present simulations showed that residual thyroid radioactivity corresponding to thyroid dose of 100 mSv can be detected within 21 days after intake at the ambient dose rate of 0.2 µSv/hr and within 11 days in the case of 2.0 µSv/hr. When a time constant of 10 seconds was used at the dose rate of 0.2 µSv/hr, the estimated survey meter output error was 5%. Evaluation of the effect of individual differences in the location of the thyroid gland confirmed that the measured value would decrease by approximately 6% for a height difference of ±1 cm and increase by approximately 65% for a depth of 1 cm. Conclusion: In the event of a nuclear disaster, simple measurements carried out using a NaI(Tl) scintillation survey meter remain effective for assessing ¹³¹I intake. However, it should be noted that the presence of short-half-life radioactive materials on the body surface affects the detection limit.

• Journal of Drive and Control
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• v.20 no.4
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• pp.27-34
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• 2023

Weeding in orchards is closely associated with productivity and quality. The customary weeding process is both labor-intensive and time-consuming. To solve the problems, there is need for automation of agricultural robots and machines in the agricultural field. On the other hand, orchards have complicated working areas due to narrow spaces between trees and amorphous terrain. Therefore, it is necessary to develop customized robot technology for unmanned weeding work within the department. This study developed a path generation and path control method for unmanned weeding according to the orchard environment. For this, the width of the weeding span, the number of operations, and the width of the weeding robot were used as input parameters for the orchard environment parameters. To generate a weeding path, a weeding robot was operated remotely to obtain GNSS-based location data along the superheated center line, and a driving performance test was performed based on the generated path. From the results of orchard field tests, the RMSE in weeding period sections was measured at 0.029 m, with a maximum error of 0.15 m. In the steering period within row and steering to the next row sections, the RMSE was 0.124 m, and 0.047 m, respectively.