• Nuclear Engineering and Technology
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• v.55 no.8
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• pp.3030-3038
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• 2023

Nowadays, mobile robots have been used to search for uncontrolled radioactive source in indoor environments to avoid radiation exposure for technicians. However, in the indoor environments, especially in the presence of obstacles, how to make the robots with limited sensing capabilities automatically search for the radioactive source remains a major challenge. Also, the source search efficiency of robots needs to be further improved to meet practical scenarios such as limited exploration time. This paper proposes an automatic source search strategy, abbreviated as ACA: the location of source is estimated by a convolutional neural network (CNN), and the path is planned by the A-star algorithm. First, the search area is represented as an occupancy grid map. Then, the radiation dose distribution of the radioactive source in the occupancy grid map is obtained by Monte Carlo (MC) method simulation, and multiple sets of radiation data are collected through the eight neighborhood self-avoiding random walk (ENSAW) algorithm as the radiation data set. Further, the radiation data set is fed into the designed CNN architecture to train the network model in advance. When the searcher enters the search area where the radioactive source exists, the location of source is estimated by the network model and the search path is planned by the A-star algorithm, and this process is iterated continuously until the searcher reaches the location of radioactive source. The experimental results show that the average number of radiometric measurements and the average number of moving steps of the ACA algorithm are only 2.1% and 33.2% of those of the gradient search (GS) algorithm in the indoor environment without obstacles. In the indoor environment shielded by concrete walls, the GS algorithm fails to search for the source, while the ACA algorithm successfully searches for the source with fewer moving steps and sparse radiometric data.

• Journal of Biomedical Engineering Research
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• v.38 no.6
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• pp.313-320
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• 2017

Myocardial infarction is a disease caused by stenosis of the coronary arteries. The high risk of sudden cardiac death due to myocardial infarction has triggered related researches that have been actively studied so far. However, these studies focused on the clinical results, which are mainly based on observations of symptoms due to infarction through electrocardiograms. Therefore, in this study, we tried to analyze the behavior of heart according to the position and volume of infarction lesion through the computer simulation study using three dimensional ventricular models. In order to implement infarction, commercial software was used to simulate cell necrosis due to blockage of a specific coronary. In addition, the conduction block due to infarction was mimicked by reducing the electrical conduction in the infarcted area, which was 100 times less than the electrical conduction of the whole ventricular lattice implemented by the finite element analysis method. Thus, this study classified the infarcted cases into the upper, middle, lower, and apex according to lattice data of eight different infraction areas. In other words, we assumed that myocardial infarction would have inherent electro-dynamic characteristics depending on the location and extent, and analyzed the ventricular electromechanical responses for infarction lesions using a three dimensional cardiac physiome model. The results showed that the volume of infarction did not directly affect the cardiac responses, but the location of the infarction lesions could influence the ventricular pumping efficiency. These suggest that the occlusion of specific coronary arteries may have a fatal effect on the decline in ventricular performance. In conclusion, although location of myocardial infarction lesions is considered to be an important variable to be considered clinically rather than lesion size, quantitative predictions should be made more in the future considering physiological factors such as lesion location and direction of myocardial fiber at that location.

• Journal of the Institute of Electronics and Information Engineers
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• v.52 no.3
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• pp.13-18
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• 2015

This paper proposes an optimum vision system analysis and a reliable high-precision positioning system that converges a GNSS and a vision system in order to resolve position error and outdoor shaded areas two disadvantages of GNSS. For location determination of the object, it should receive signal from at least four GNSS. However, in urban areas, exact location determination is difficult due to factors like high buildings, obstacles, and reflected waves. In order to deal with the above problem, a vision system was employed. First, determine an exact position value of a target object in urban areas whose environment is poor for a GNSS. Then, identify such target object by a vision system and its position error is corrected using such target object. A vehicle can identify such target object using a vision system while moving, make location data values, and revise location calculations, thereby resulting in reliable high precision location determination.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.2
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• pp.459-462
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• 2005

In this paper, we investigate the high precision location estimation algorithm in 2.45GHz band RTLS with multiple tags. The location is estimated in LOS environments, 300m ${\times}$ 300m area, and 2D coordinates adopting a TDOA scheme which is not necessitate the transmission time of tags. We evaluate the average estimation error in distance assuming that tags are randomly distributed and the readers(3${\sim}$8) are uniformly(equal space) placed in test area. In results, average estimation error is 3.12m and 1.47m at reader numbers of 4 and 8, respectively. Minimum estimation error is obtained when the accumulated receiving signal from a tag is 3 or 4 regardless of available reader numbers. The error is less than 3m, satisfies the specification of RTLS.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.23 no.6
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• pp.631-636
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• 2019

In recently, various kinds of services utilizing the location information of the user's smart phone have appeared. Based on this trend, we designed a new type of learning assistant system that utilizes geofencing technology, which is a field of location information technology. This system identifies the location of the classroom using the location information of learner's the smart phone and automatically provides the necessary learning contents to the learner's smart phone when the learner enters the classroom set as the virtual fence area while carrying the smart phone respectively. Our system provides learning contents in a form similar to the form of a message or a mobile coupon and learners are used to such mobile service environments very much. So the use of learning contents provided by our system is expected to help improve the learning effect of learners.

• Nuclear Engineering and Technology
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• v.53 no.5
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• pp.1556-1568
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• 2021

The plate-type fuel assembly adopted in nuclear research reactor suffers from complicated effect induced by non-uniform irradiation, which might affect stress conditions, mechanical behaviors and thermal-hydraulic performance of the fuel assembly. This paper is the Part II work of a two-part study devoted to analyzing the complex unique mechanical deformation and thermal-hydraulic characteristics for the typical plate-type fuel assembly under irradiation effect, which is on the basis of developed and verified numerical thermal-fluid-structure coupling methodology under irradiation in Part I of this work. The mechanical deformation, thermal-hydraulic performance and Mises stress have been analyzed for the typical plate-type fuel assembly consisting of support plates under non-uniform irradiation. It was interesting to observe that: the plate-type fuel assembly including the fuel plates and support plates tended to bend towards the location with maximum fission rate; the hot spots in the fuel foil appeared at the location with maximum thickness increment; the maximum Mises stress of fuel foil was located at the adjacent location with the maximum plate thickness increment et al.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.21 no.48
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• pp.1-14
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• 1998

This paper describes a study which was undertaken in Ulsan City. The modified SLP procedures consider the quantitative flow aspect of the facilities layout problem as well as the qualitative closeness rating aspect. Conclusions are drawn as to the effectiveness of the proposed model in providing Ulsan City with better means of making the facilities location allocation decision for Industrial Technology Research Park.

• Proceedings of the KSR Conference
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• 2007.05a
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• pp.1707-1713
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• 2007

If GNSS-based location information, expected to become the mainstream of the future technology, is applied to the future transportation, it will be of benefit to as follows; cost reducing effects on operating expanse and constructing expense due to decrease of ground unit installation, development of new technologies for train, or vehicle control system and becoming a front runner in the market. Therefore, this paper provides the minimum requirements for GNSS based system thru the studies on the applicability of GNSS based system to railway system, distinctions of the new technology between the existing technologies, and location accuracy.

• Fisheries and Aquatic Sciences
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• v.4 no.3
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• pp.159-161
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• 2001

• Journal of the Korea Society of Computer and Information
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• v.12 no.6
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• pp.115-121
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• 2007

Recently, Location Based Service including tracking and way-finding services has been activated rapidly in the ubiquitous computing environment. According as the ubiquitous computing environment is developed, various types of sensor to acquire various data including location of the moving object are used widely, and acquired sensor data becomes abundant. However, the existing location management system based on a single location sensor is difficult to support LBS efficiently in the ubiquitous computing environment. In this paper, therefore, we propose the location management system in the ubiquitous computing environment that can manage the location data and the various sensor data efficiently. In addition, the location management system adopts the core technology for efficiently storing and transferring a large-volume of various data such as location data and for efficiently processing the various requests from a variety of servers and sensors. Especially, our architecture that is presented in this paper can support context-aware services and autonomous services efficiently in the ubiquitous computing environment.