• Journal of Institute of Control, Robotics and Systems
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• v.22 no.1
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• pp.24-30
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• 2016

The accuracy of small and low-cost CCD cameras is insufficient to provide data for precisely tracking unmanned aerial vehicles (UAVs). This study shows how a quad rotor UAV can hover on a human targeted tracking object by using data from a CCD camera rather than imprecise GPS data. To realize this, quadcopter UAVs need to recognize their position and posture in known environments as well as unknown environments. Moreover, it is necessary for their localization to occur naturally. It is desirable for UAVs to estimate their position by solving uncertainty for quadcopter UAV hovering, as this is one of the most important problems. In this paper, we describe a method for determining the altitude of a quadcopter UAV using image information of a moving object like a walking human. This method combines the observed position from GPS sensors and the estimated position from images captured by a fixed camera to localize a UAV. Using the a priori known path of a quadcopter UAV in the world coordinates and a perspective camera model, we derive the geometric constraint equations that represent the relation between image frame coordinates for a moving object and the estimated quadcopter UAV's altitude. Since the equations are based on the geometric constraint equation, measurement error may exist all the time. The proposed method utilizes the error between the observed and estimated image coordinates to localize the quadcopter UAV. The Kalman filter scheme is applied for this method. Its performance is verified by a computer simulation and experiments.

• The Journal of the Convergence on Culture Technology
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• v.6 no.1
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• pp.463-469
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• 2020

People enjoy more leisure time these days as the government introduced the workweek last year and there is a growing interest on living healthy life. Amidst such change in society, trekking in forest has gained popularity along more people spending leisure time by walking for health. As a result, there are many scenic trails being built using wood deck. Usually certain parts of trails are built with wood deck where the path maybe too dangerous for walking or where nature needs to be protected. However wood material used for deck is easily prone to defects which can lead to safety issues. This study aims to understand the differences by materials used for wood deck and to investigate a link between different materials used and causes for defect occurrence. And further, the study aims to identify materials and construction methods for high workability and safety. The study was able to conclude that different materials used and different construction methods of applied for wood deck yield different results in terms of workability and defect occurrence.

• Journal of Korean Society of Transportation
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• v.27 no.5
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• pp.189-194
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• 2009

Transfer impedance is one of the most critical factors decreasing the competitive power of public transportation. Therefore, it is necessary to improve transfer impedance of KTX and rail station users in order to increase the usage of public transportation. Important factors influencing transfer decisions include exterior walking distance, interior walking distance, steps, and escalators. However, their comparative impedances are different. This study constructed a model for calculating transfer impedance based on bodily sensational transfer time in KTX and rail stations and calculated transfer impedance on major KTX and rail stations in Korea. The study results show that the addition of one escalator decreases travel time by one to three minutes. The calculated transfer impedance based on bodily sensational transfer time in this study can be utilized as objective criteria to compare transfer conditions of different KTX and rail stations and to prioritize them for facility improvement. The calculated transfer impedance also can be used as facility guidelines for designing a new transit center.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.22 no.3
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• pp.62-72
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• 2023

Recently, the importance of monitoring and management measures for bicycle road related facilities has been increasing. However, research on the monitoring and evaluation of users' safety and convenience in walking spaces including bicycle path is insufficient. In this study, we would like to construct health monitoring data for cylists-pedestrians mixed road using a mobile mapping system, and propose a plan to calculate the level of service of the mixed roads from the perspective of pedestrians and cyclists using artificial intelligence based object detection techniques. The monitoring and level of service calculation method of cylists-pedestrians mixed roads proposed in this study is expected to be used as basic information for planning and management such as maintenance and reconstruction of walking spaces in preparation for the increase of electric bicycles and personal mobility in the future.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.30 no.2D
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• pp.99-103
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• 2010

It is necessary to improve transfer impedance of express bus terminal users in order to increase the usage of public transportation. This study constructed a model for calculating transfer impedance based on bodily sensational transfer time in express bus terminal and calculated transfer impedance on major express bus terminals in Korea. The study results show that the addition of 100 meter exterior walking distance increases 3 minute travel time, 100 meter interior walking distance increases 5 minute travel time, 100 stairways increase 13 minute travel time, and escalators decreases 3 minute travel time. The calculated transfer impedance based on bodily sensational transfer time in this study can be utilized as objective criteria to compare transfer conditions of different bus terminals and to prioritize them for facility improvement. The calculated transfer impedance also can be used as facility guidelines for designing a new transit center.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.30 no.1D
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• pp.11-15
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• 2010

It is necessary to improve transfer impedance of Urban Rail Station station users in order to increase the usage of public transportation. This study constructed a model for calculating transfer impedance based on bodily sensational transfer time in Urban Rail Station stations and calculated transfer impedance on major Urban Rail Station stations in Korea. The study results show that the addition of 100 meter exterior walking distance increases 2 minute travel time, 100 meter interior walking distance increases 3 minute travel time, 100 stairways increase 4 minute travel time, and escalators decreases 1 minute travel time. The calculated transfer impedance based on bodily sensational transfer time in this study can be utilized as objective criteria to compare transfer conditions of different Urban Rail Station stations and to prioritize them for facility improvement. The calculated transfer impedance also can be used as facility guidelines for designing a new transit center.

• Journal of the Korean Regional Science Association
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• v.33 no.1
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• pp.29-41
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• 2017

This study proposes an integrated accessibility measurement algorithm, which is applied to the Seoul Metropolitan public transportation system consisting of bus and subway networks, and analyzes the result. We construct a public transportation network graph linking bus-subway networks and take the time distance as the link weight in the graph. We develop a time-distance algorithm to measure the time distance between each pair of transit stations based on the T-card transaction database. The average travel time between nodes has been computed via the shortest-path algorithm applied to the time-distance matrix, which is obtained from the average speed of each transit route in the T-card transaction database. Here the walking time between nodes is also taken into account if walking is involved. The integrated time-distance accessibility of each node in the Seoul Metropolitan public transportation system has been computed from the T-card data of 2013. We make a comparison between the results and those of the bus system and of the subway system, and analyze the spatial patterns. This study is the first attempt to measure the integrated time-distance accessibility for the Seoul Metropolitan public transportation system consisting of 16,277 nodes with 600 bus routes and 16 subway lines.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.21 no.5
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• pp.15-27
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• 2022

An omnidirectional VR treadmill is a highly-immersive walking simulator that allows identical body movements, such as walking, running, and sitting. However, the operation difficulty of an omnidirectional VR treadmill may cause data reliability problems. Therefore, this study aims to verify the effectiveness of a VR treadmill by comparing the ability to orient in the real and virtual worlds spatially. For this purpose, a rotating and searching path experiment was conducted with participants. This experiment showed that there was no statistically significant difference in the ability of the participants to orient in the real and virtual worlds spatially. In addition, the omnidirectional VR treadmill requires an adaptation time for the users due to the difficulty in the treadmill operation. However, there was no significant difference in the difficulty felt by the participants according to the adaptation time. Hence, these findings supported the possibility of collecting realistic walking data without safety concerns through an omnidirectional VR treadmill. Furthermore, this treadmill could be used in future research to solve problems directly related to pedestrian safety, such as the interaction between vehicles and pedestrians.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.10
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• pp.415-420
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• 2020

Crowd flows occur in metropolitan railway transit stations, terminals, multiple buildings, and stadiums and are important in ensuring the safety as well as smooth flow of pedestrians in these facilities. In this study, the author developed a new computational analysis method for crowd flow dynamics and applied it to models of transit connecting paths. Using the analysis method, the potential value of the exit was assigned the smallest value, and the potential value of the surrounding grids gradually increased to form the overall potential map. A pathline map was then constructed by determining the direction vector from the grid with large potential value to the grid and small potential. These pathlines indicate basic routes of passenger flow. In all models of the analysis object, the pedestrians did not move to the first predicted shortest path but instead moved using alternative paths that changed depending on the situation. Even in bottlenecks in which pedestrians in both directions encountered each other, walking became much smoother if the entry time difference was dispersed. The results of the analysis show that a method for reducing congestion could be developed through software analysis such as passenger flow analysis without requiring hardware improvement work at the railway station.

• Physical Therapy Rehabilitation Science
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• v.9 no.1
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• pp.10-17
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• 2020

Objective: Hallux valgus (HV) is a common musculoskeletal deformity that is accompanied with pain and continues to decrease one's quality of life and ability to perform daily life activities by affecting gait and static stability. Therefore, this study aimed to investigate the effect of the angle of HV (HVA) and to compare the one-legged stance and gait parameters in young adults with less HV and severe HV. Design: Cross-sectional study. Methods: Forty young adults were divided into two groups, where HVA ≥15° (n=20) was defined as HV, and HVA <15° (n=20) was defined as normal. For balance ability, the center of pressure (COP) path, velocity, length of axis of the COP path, deviation of the x-axis and y-axis, and percentage of foot pressure were measured, and gait, the foot rotation angle, step length, percentage of each phase of the gait cycle, time change from the heel to forefoot, and maximum pressure of the forefoot and midfoot were measured. Results: Significant differences were found in sway length and time change from heel to forefoot during walking between the normal and HV groups (p<0.05). Most parameters were not associated with the HVA, but parameters such as length of axis and time to change from heel to forefoot were significantly associated with the HVA (p<0.05). Conclusions: These results suggest that most one-legged stance and gait parameters were not significantly affected by the HVA in young adults; therefore, future studies are needed in order to address other dynamic parameters and other methods of gait analysis for detecting clinically meaningful conditions.