• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
• /
• v.30 no.6_1
• /
• pp.539-547
• /
• 2012

Volume survey for earthwork is conducted periodically at every month at large scaled construction sites for request payment for the construction. Currently, the earthwork volume is calculated on the overlapped drawing for two cross sections which were created by new and previous surveying data observed by GPS and TS. However the survey is required lots of time and expenses as it is a pin-point surveying method thus surveyors intend to get data only for the heavy undulated topographic features chosen by himself to save time and expenses. Consequently, it causes poor results due to low dense measurement as well as it's not matched with the results by another surveyors. As a result, the conflicts related in earthwork volume calculation often arises among the owner, contractors and sub contractors. In this study, we developed a method to get surveying data for fast and accurate volume calculation using 3D Mobile Laser System and conducted an application test. Also we carried out experiments for topographic survey using MLS to judge for the application additionally. The results showed that we could reduce a time for cross section survey from 48 hours to 2 hours and collected high dense data which have 0.2m interval instead of 3m interval compare with existing method. Also we could make a map which has high accuracy within 10cm in horizontal through topographic survey using MLS.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.13 no.10
• /
• pp.2004-2010
• /
• 2009

The characteristic of the backbond for distribution service in WMNs(Wireless Mesh Networks) is that WMNs has multiple links connected to mesh points and dynamic routing protocol such as AODV to establish routing paths. When the terminal is communicating with the service through new AP, mobile nodes can resume communication by setting only the link between new AP and mobile node in the case of existing WLANs, but WMNs needs path establishment process in multihop networks. Our goal in this paper is to support the seamless communication service by eliminating path establishment delay in WMNs. We present the method that eliminates the handover latency by predicting the location of handover using GPS information and making the paths to their destination in advance. We implement mesh nodes using embedded board that contains proposed handover method and evaluate performance of handover latency. Our experiment shows that handover delay time is decreased from 2.47 to 0.05 seconds and data loss rate is decreased from 20~35% in the existing method to 0~10% level.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.39 no.5
• /
• pp.605-612
• /
• 2019

Traditionally, travel demand forecasts have been conducted based on the data collected by a survey of individual travel behavior, and their limitations such as the accuracy of travel demand forecasts have been also raised. In recent, advancements in information and communication technologies are enabling new datasets in travel demand forecasting research. Such datasets include data from global positioning system (GPS) devices, data from mobile phone signalling, and data from call detail record (CDR), and they are used for reducing the errors in travel demand forecasts. Based on these background, the objective of this study is to assess the feasibility of CDR as a base data for travel demand forecasts. To perform this objective, CDR data collected for Daegu Metropolitan area for four days in April including weekdays and weekend days, 2017, were used. Based on these data, we analyzed the correlation between CDR and travel demand by travel survey data. The result showed that there exists the correlation and the correlation tends to be higher in discretionary trips such as non-home based business, non-home based shopping, and non-home based other trips.

• Journal of the Korea Society for Simulation
• /
• v.31 no.3
• /
• pp.55-61
• /
• 2022

Currently police and fire departments use a Network/Wifi/GPS based emergency location positioning system established by mobile carriers to directly link with the device of the people who request the rescue to accurately position the expected location in the call area. However in the case of mountain rescue it is difficult to rescue the victim in golden time because the location of the search area cannot be limited when the victim is located in a radio shadow area of the mountain or the device power is off and this situation become worse if victim fail to report 911 by himself due to the injury. In this paper, we are expected to solve the previous problem by propose the mobile telecommunication forensic simulator consist of time series of cell information, human mobility model which include some general and specific features (age, gender, behavioral characteristics of victim, etc.) and intelligent infer system. The results of analysis appear in heatmap of polygons on the map based on the probability of the expected location information of the victim. With this technology we are expected to contribute to rapid and accurate lifesaving by reducing the search area of rescue team.

• Journal of Digital Convergence
• /
• v.18 no.3
• /
• pp.163-169
• /
• 2020

A smart key has been used in a variety of embedded environments and there also have been attacks from a remote place by amplifying signals at a location of a user. Existing studies on defence techniques suggest multiple sensors and hash functions to improve authentication speed; these, however, increase the electricity usage and the probability of type 1 error. For these reasons, I suggest an embedded security controller based on client authentication and user movement information improving the authentication method between a controller and a host device. I applied encryption algorithm to the suggested model for communication using an Arduino board, GPS, and Bluetooth and performed authentication through path analysis utilizing user movement information for the authentication. I found that the change in usability was nonsignificant when performing actions using the suggested model by evaluating the time to encode and decode. The embedded security controller in the model can be applied to the system of a remote controller for a two-wheeled vehicle or a mobile and stationary host device; in the process of studying, I found that encryption and decryption could take less then 100ms. The later study may deal with protocols to speed up the data communication including encryption and decryption and the path data management.

• Journal of Korea Society of Industrial Information Systems
• /
• v.19 no.4
• /
• pp.53-63
• /
• 2014

Moving context determination is an important issue to be resolved in a mobile computing environment. This paper presents a method for recognizing and classifying a mobile user's moving context by Euclidean distance similarity. In the proposed method, basic data are gathered using Global Positioning System (GPS) and accelerometer sensors, and by using the data, the system decides which moving situation the user is in. The decided situation is one of the four categories: stop, walking, run, and moved by a car. In order to evaluate the effectiveness and feasibility of the proposed scheme, we have implemented applications using several variations of Euclidean distance similarity on the Android system, and measured the accuracies. Experimental results show that the proposed system achieves more than 90% accuracy.

• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.47 no.1
• /
• pp.35-42
• /
• 2010

Geo-location using a cellular network is a core technology for LBS together with GPS. With preamble symbols broadcasted in each frame, geo-location using WiBro network can be easily implemented. Because the WiBro network has a cellular structure, it is difficult for a mobile station to detect signals from multiple base stations. In order to get user position using trilateration, long integration techniques for sensitivity enhancement should be employed. This paper presents hybrid integration scheme for WiBro network. By analyzing coherent and non-coherent integration loss according to frequency residual and SNR respectively, optimal combination of the hybrid integration is proposed. Simulation results show that the hybrid integration method is profitable in WiBro network when the frequency residual is estimated and compensated accurately.

• Spatial Information Research
• /
• v.18 no.3
• /
• pp.53-62
• /
• 2010

Recent development in wireless communication technology, like GPS, and mobile equipments, like PDA and cellular phone, make location-based services (LBSs) popular. However, because, users continuously request a query to a server in the LBSs by using their exact locations, privacy information could be in danger. Therefore, a mechanism for users' privacy protection is required for the safe and comfortable use of LBSs by mobile users. For this, we, in this paper, propose a grid-based cloaking area creation scheme supporting continuous LBSs in peer-to-peer environment. The proposed scheme creates a cloaking area by using Chord protocol, so as to support the continuous LBSs in peer-to-peer environment. Finally, we show from a performance analysis that our cloaking scheme outperforms the existing cloaking schemes, in terms of service time.

• 한국정보통신설비학회:학술대회논문집
• /
• 2007.08a
• /
• pp.427-431
• /
• 2007

Applications in present-day mobile communication systems particularly require miniaturized dimensions and low-profiles of antenna in order to meet the mobile units. Thus, size reductions and bandwidth enhancements are becoming crucial design considerations for practical applications of microstrip antennas. The motivation of further experiments have been stepped to follow those studies for achieving compact and broadband, even multiplied operation modes, which are greatly increased with much attentions recently. To obtain broadband, single-feed, circularly polarized characteristics of microstrip antennas, a design with feed-line ought to be a factor of two. Usually, diagonally balanced-line feeds with hybrid coupler are employed to attain circular polarizations. We firstly formulated DGS (Defected Ground Structures) based operation principles of the entire microstrip components and therefore were able to derive impedance variance of feed-lines. After verifying corresponding experimental results, we targeted the frequency bands of UHF RFID (Ultra High Frequency Radio Frequency IDentification) and approximately of 0.4-2.4GHz have exhibited remarkable two resonance amplitudes as a dual band antenna. Our secondary researches were aimed to design quad band microstrip antenna which represents four resonance characteristics within the identical frequency bands as well. Microstrip patch has been meandered to lengthen the electrical paths, and the other design criteria with respecting physical parameters including radiation patterns and impedance bandwidths measurements will be described for verification. Advisable applications of these antennas can be GSM850, GSM900, GPS (L1-1575 and L2-1227) and UMTS-2110 of cellular systems, which extremely desire multiband and minimum size.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.38C no.8
• /
• pp.663-673
• /
• 2013

The drastic growth of mobile communication and spreading of smart phone make the significant attention on Location Based Service. The one of most important things for vitalization of LBS is the accurate estimating position for mobile object. Focusing on IMU deployed in smart phone, we develop a hybrid positioning estimation framework with a combination of WPS. The developed approaches can strengthen the advantages of independent indoor applicability of IMU. The estimation of IMU is efficiently compensated by radio fingerprint based Wi-Fi Positioning System. We put a focus especially on the hybrid algorithmic framework. Compared on the existing approaches of WPS or IMU, we achieve the comparable higher performance on both of average error of estimation and deviation of errors. Furthermore test-bed based on smart phone platform is practically developed and all data have been harvested from the actual measurement of test indoor area. This can approve the practical usefulness of proposed framework.