• KSCE Journal of Civil and Environmental Engineering Research
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• v.39 no.5
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• pp.605-612
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• 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 Korean earth science society
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• v.40 no.1
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• pp.37-45
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• 2019

In spite of continued nourishments, Haeundae Beach in Busan has been suffering from erosion, this being caused by the increased wave energy due to global warming and intermittent typhoon reported by previous works. In the meantime, the typhoon Chaba hit Basan in October 2016. In order to investigate the effects of the typhoon in beach erosion and how fast the beach recovered after the typhoon, repeated beach profiling using a VRS-GPS system was carried out, and the grain size analyses for surface sediments sampled on the beach were conducted. Immediately after the typhoon invasion, Haeundae beach was eroded by 1.4 m in average height. The mean high tide lines were retreated back by 12 m, and beach slope became gentler from $3.8^{\circ}$ to $1.7^{\circ}$. The mean grain sizes of surface sediments became coarser from $1.6{\Phi}$ to $1.2{\Phi}$ after two months, and the sorting well sorted. After two months of typhoon landfall, the mean high tide lines have recovered by 85%, and the beach topography almost recovered. This suggests that the impact of typhoons on Haeundae beach erosion is negligible, and the relaxation time is shorter than that of other beaches.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.19 no.6
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• pp.222-234
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• 2020

Autonomous vehicles are equipped with a wide rage of sensors such as GPS, RADAR, LIDAR, camera, IMU, etc. and are driven by recognizing and judging various transportation systems at intersections in the city. The accident ratio of the intersection of the autonomous vehicles is 88% of all accidents due to the limitation of prediction and judgment of an area outside the sensing distance. Not only research on non-signalized intersection collision avoidance strategies through V2V and V2I is underway, but also research on safe intersection driving in failure situations is underway, but verification and fragments through simple intersection scenarios Only typical V2V failures are presented. In this paper, we analyzed the architecture of the V2V module, analyzed the causal factors for each V2V module, and defined the failure mode. We presented intersection scenarios for various road conditions and traffic volumes. we used the ISO-26262 Part3 Process and performed HARA (Hazard Analysis and Risk Assessment) to analyze the risk of autonomous vehicle based on the simulation. We presented ASIL, which is the result of risk analysis, proposed a monitoring concept for each component of the V2V module, and presented monitoring coverage.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.22 no.2
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• pp.164-181
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• 2023

In a low speed limit environment, the speed limit tolerance of automated traffic enforcement devices is very high, which is one of the main factors for the low compliance rate. Therefore, in this study, we aimed to the improve the speed limit tolerance and to present a new standard. The effects of the operator and user errors that can cause speeding by drivers were analyzed. Based on the results of the analysis, an improvement of the tolerance was proposed by applying an error in the enforcement device and GPS speed. In addition, long-term expected safety effects such as the accident rate and severity were estimated from the operator's perspective when improving the tolerance. As a result of the estimation, the speed limit compliance rate, accident rate, and change rate of a number of severe accidents due to speed change, and pedestrian traffic accident mortality rate were all improved in all speed limit environments. The introduction of the proposed improvement is expected to improve road safety significantly.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.22 no.4
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• pp.313-321
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• 2004

Korean government has offcially decided to adopt global geodetic reference system(ITRF and GRS80) from 2007 keeping pace with the spread of GNSS. Industries related with LBS and telematics have called for use of the new coordinate system suitable for GIS/GPS applications. The government also defined the single plane coordinate system that covers entire korean peninsula as UTM-K considering DB-based framework data and user-friendliness, and its defects were corrected while being applied to the building of road framework data. The TM projection, and origin scale factor of plane coordinate system, 0.9996were employed in order to satisfy the single plane coordinate system for the entire Korean peninsula. For the origin of plane coordinate system, longitude of $127^{\circ}$30'00" and latitude of $38^{\circ}$00'00" were applied and, for the initial value of plane coordinate system, N=2,000.000m and E=1,000,000m were used. In addition to considerable savings in costs, it is expected that the UTM-K is applicable for correcting errors occurred during acquisition of geographic information and for aggregating map data produced by different sources. However, during the initial stage for introduction, confusion is forecasted due to the use of two different coordinate systems, which may be minimized by continued publicity and education.

• International conference on construction engineering and project management
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• 2009.05a
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• pp.869-875
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• 2009

Safety is a big issue in the construction sites. For safe and secure management, tracking locations of construction resources such as labors, materials, machineries, vehicles and so on is important. The materials, machineries and vehicles could be controlled by computer, whereas the movement of labors does not have fixed pattern. So, the location and movement of labors need to be monitored continuously for safety. In general, Global Positioning System(GPS) is an opt solution to obtain the location information in outside environments. But it cannot be used for indoor locations as it requires a clear Line-Of-Sight(LOS) to satellites Therefore, indoor location monitoring system could be a convenient alternative for environments such as tunnel and indoor building construction sites. This paper presents a case study to investigate feasibility of Wi-Fi based indoor location monitoring system in construction site. The system is developed by using fingerprint map of gathering Received Signal Strength Indication(RSSI) from each Access Point(AP). The signal information is gathered by Radio Frequency Identification (RFID) tags, which are attached on a helmet of labors to track their locations, and is sent to server computer. Experiments were conducted in a shield tunnel construction site at Guangzhou, China. This study consists of three phases as follows: First, we have a tracking test in entrance area of tunnel construction site. This experiment was performed to find the effective geometry of APs installation. The geometry of APs installation was changed for finding effective locations, and the experiment was performed using one and more tags. Second, APs were separated into two groups, and they were connected with LAN cable in tunnel construction site. The purpose of this experiment was to check the validity of group separating strategy. One group was installed around the entrance and the other one was installed inside the tunnel. Finally, we installed the system inner area of tunnel, boring machine area, and checked the performance with varying conditions (the presence of obstacles such as train, worker, and so on). Accuracy of this study was calculated from the data, which was collected at some known points. Experimental results showed that WiFi-based indoor location system has a level of accuracy of a few meters in tunnel construction site. From the results, it is inferred that the location tracking system can track the approximate location of labors in the construction site. It is able to alert the labors when they are closer to dangerous zones like poisonous region or cave-in..

• Journal of Digital Convergence
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• v.19 no.2
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• pp.221-230
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• 2021

The study attempts to suggest potential problem and solutions expected in the process of implementing KASS, which is currently under development to improve the domestic navigation safety system, and to summarize improvement effects of domestic navigation safety system anticipated by the implementation of KASS. Challenges expected in the process of implementing KASS exists in four aspects: emotional, technical, cost, safety aspects. When KASS is implemented and operates, various benefits can be realized. Benefits include cost savings by not using navigation safety systems during takeoff and landing; reduction of flight delays and cancellations by removing airway congestion; increase of aircraft accommodation capacity; reduction of carbon emissions; preparation for future aviation demands and improvement of air transportation safety; and reduction of flight accidents. In conclusion, it is expected to enter into an era of more intense competition due to increased aviation demands. In order to survive in this competitive environment, early introduction of KASS is indispensable. Analysis results of this study are expected to provide reference information for academic research in this area. A possible future research topic include a study predicting the changes in the navigation safety systems introduced by KASS and proposing practical and useful ways to respond the changes.

• Journal of Biosystems Engineering
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• v.37 no.4
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• pp.225-232
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• 2012

Purpose: Accurate monitoring of information from various agricultural vehicles is one of the most important factors for appropriate management strategy of field operations. While there has been a number of study and design on applications of sensors and actuators for data acquisition and control system in tractor, incompatibility between various customized hardware and software has become a major obstacle to the universal deployment in real field operation. International standard for implementation of electronic control unit (ECU) in agricultural vehicles has becoming a mandatory requirement for inter-operation compatibility in the international trade of agricultural vehicle industries. The ISO 11783 standard is basically based upon well known communication technology designated using the controller area network (CAN) bus. While CAN bus could provide 1.0 Mbps of communication speed, the standard only recommended 250 kbps. Methods: This study presents the implementation and evaluation of ISO 11783 for tractor electronic control units (TECU)with a higher transmission rate from multiple ECU than 250 kbps. Throughput and loss rate of the developed prototype were calculated across manipulated bus load for laboratory experimental tests, and the maximum requirement of transmission rate by ISO 11873 was satisfied with lower than 60% of bus load. Results: Field tests with a TECU implemented to process messages from global positioning system (GPS) receiver resulted that the root mean square error of position information was lower than 4 m with 0.5 m/s as a travelling speed. Conclusions: Results of this study represent the utilization of the international standard ISO 11783 to providepractical developments in terms with the inter-operability of TECU.

• Journal of the Korean Association of Geographic Information Studies
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• v.13 no.2
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• pp.54-63
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• 2010

The intensive rainfall over 455 mm occurred between on 9 to 14 July 2009 triggered debris flows around the mountain area in Jecheon County. We mapped the debris flow area and estimated the debris flow volume using a high resolution digital elevation model (DEM) generated respectively from terrestrial LiDAR (Light Detection And Ranging) and topographic maps. For the LiDAR measurement, the terrestrial laser scanning system RIEGL LMS-Z390i which is equipped with GPS system and high-resolution digital camera were used. After the clipping and filtering, the point data generated by LiDAR scanning were overlapped with digital map and produced DEM after debris flow. The comparison between digital map and LiDAR scanning result showed the erosion and deposition volumes of about $17,586m^3$ and $7,520m^3$, respectively. The LiDAR data allowed comprehensive investigation of the morphological features present along the sliding surface and in the deposit areas.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38C no.12
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• pp.1196-1206
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• 2013

In this paper, based on the information about navigation system of UAV with PTZ camera and 3D topography, algorithm able to show us in real-time UAV's geographical shooting location and automatically calculate superficial measure of the shooting area is proposed. And the method that can automatically estimate whether UAV is allowed to shoot a specific area is shown. In case of an UAV's shooting attempt at the specific area, obtainability of valid image depends on not only UAV's location but also information of 3D topography. As a result of the study, Ground Control Center will have real-time information about whether UAV can shoot the needed topography. Therefore, accurate remote flight control will be possible in real-time. Furthermore, the algorithm and the method of estimating shooting probability can be applied to pre-flight simulation and set of flight route.