• Journal of Cadastre & Land InformatiX
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• v.52 no.2
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• pp.153-169
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• 2022

With the extension of the average life span and the rapid aging of the population, defining elderly population as a single group is difficult as the physical, economic and social conditions of individual have become different. Therefore, policies that take into account the characteristics of each group are required. The purpose of this study is to classify individual travel types and to analyze the characteristics of each travel type, based on individual public transportation trajectory data as known as smart card data. Among the four classified types, the long-distance low-frequency stay type and the short-range medium-frequency mobile type show external activity traffic characteristics for retirement leisure, while the long-distance high-frequency stay type and the long-distance high-frequency mobile group include regular commuting. Traffic variability and residence areas of stay were identified in terms of each classified travel type. The results of this study provide the important suggestions for establishing a transportation policy that takes into account the characteristics of each type of elderly population in Seoul.

• Proceedings of the KIEE Conference
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• 1991.07a
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• pp.763-766
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• 1991

The moving of each axis in the robot manipulator can be represented with the motion of cartesian space. This paper shows the robot manipulator of the straight line trajectory planning algorithms in the cartesian space. The relation formulas between cartesian space and joint space are induced to accomplish a desired trajectory in the cartesian space and the velocity vector of sampling time in the cartesian space is transformed into the velocity vector of joint by the interpolation method. The error of trajectory in moving is removed by obtaining the real position for the present joint position and the desired distance is made by comparing the real position and the next position. Through the simple tests for suggested algorithms are confirmed the validity of algorithms.

• Transactions of the Korean Society of Mechanical Engineers
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• v.15 no.5
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• pp.1495-1502
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• 1991

본 연구에서는 동일 작업 공간내에서 두대의 로봇이 각각의 토크의 제한 조건 과 충돌 회피 조건을 만족하면서 근사 최소 시간에 지정된 경로를 주행하기 위한 궤적 계획법을 제안하고자 한다. 이때, 동작 우선도에 의하여 한 대의 로봇은 주 로봇, 다른 한 대의 로봇은 종 로봇으로 지정되는데 주 로봇은 입력 토크의 제한조건을 만족 하며 주어진 경로를 최소 시간에 움직이도록 궤적 계획을 하였으며, 종 로봇은 주 로 봇과의 충돌을 피하고 입력 토크의 제한 조건을 만족하며 주어진 경로를 근사 최소 시 간에 움직이도록 하였다.

• Advanced Composite Materials
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• v.17 no.1
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• pp.1-23
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• 2008

Robotized filament winding technology involves a robot that winds a roving impregnated by resin on a die along the directions of stresses to which the work-piece is submitted in applications. The robot moves a deposition head along a winding trajectory in order to deposit roving. The trajectory planning is a very critical aspect of robotized filament winding technology, since it is responsible for both the tension constancy and the winding time. The present work shows two original rules to plan the winding trajectory of structural parts, whose shape is obtained by sweeping a full section around a 3D curve that must be closed and not crossing in order to assure a continuous winding. The first rule plans the winding trajectory by approximating the part 3D shape with straight lines; it is called the discretized rule. The second rule defines the winding trajectory simply by offsetting a 3D curve that reproduces the part 3D shape, of a defined distance; it is called the offset rule. The two rules have been compared in terms of roving tension and winding time. The present work shows how the offset rule enables achievement of both the required aims: to manufacture parts of high structural performances by keeping the tension on the roving near to the nominal value and to markedly decrease the winding time. This is the first step towards the optimization of the robotized filament winding technology.

• Journal of KIISE
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• v.43 no.1
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• pp.40-46
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• 2016

Digital road map generation is primarily based on artificial satellite photographing or in-site manual survey work. Therefore, these map generation procedures require a lot of time and a large budget to create and update road maps. Consequently, people have tried to develop automated map generation systems using GPS trajectory data sets obtained by public vehicles. A fundamental problem in this road generation procedure involves the extraction of representative trajectory such as main roads. Extracting a representative trajectory requires the base data set of piecewise line segments(GPS-trajectories), which have close starting and ending points. So, geometrically similar trajectories are selected for clustering before extracting one representative trajectory from among them. This paper proposes a new divide- and-conquer approach by partitioning the whole map region into regular grid sub-spaces. We then try to find similar trajectories by sweeping. Also, we applied the $Fr{\acute{e}}chet$ distance measure to compute the similarity between a pair of trajectories. We conducted experiments using a set of real GPS data with more than 500 vehicle trajectories obtained from Gangnam-gu, Seoul. The experiment shows that our grid partitioning approach is fast and stable and can be used in real applications for vehicle trajectory clustering.

• Journal of Oral Medicine and Pain
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• v.21 no.1
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• pp.55-65
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• 1996

This study was performed to investigate the effects of head posture and occlusal splint on the vertical dimension in mandibular rest position and swallowing. Thirty health dental students ware selected lot this study and BioEGNⓡ(Bioresearch Inc., USA) was used for measuring interocclusal distance during rest - swallowing - rest - tapping movement. This swallowing movements were observed in both normal head posture(NHP) and forward head posture (FHP). Thickness of occlusal splint was about 2mm at posterior molar area and even tooth contact were achieved on light biting. The four mandibular positions at which interocclusal distance measured were swallowing position, after swallowing position in which interocclusal distance was maximum, rest position follows swallowing, and tapping position after rest. Changes of distance in each position were measured for three mandibular planes, that is, sagittal, frontal, and horizontal plane, respectively. The results obtained were as follows : 1. In normal head posture, the mandible was raised 1.03mm without splint, and 0.77mm with splint on swallowing, and there was no significant difference between the two. In horizontal plane, however, mandible was displaced more anteriorly in both swallowing position and tapping position with splint. 2. In forward head posture, the mandible was less raised with splint on swallowing, but features in horizontal plane were almost same as those in normal head posture. 3. In natural dentition, significant difference between NHP and FHP were observed in horizontal plane trajectory for swallowing and tapping position. But the difference for same positions were observed in frontal trajectory with splint. 4. Total amount of mandibular movement of two groups classified with sagittal interocclusal distance of swallowing position generally showed significant difference between the higher and the lower height group in head posture without splint. 5. Correlationship among total amount of mandibular movement for three mandibular planes were observed between sagittal plane and horizontal plane, and between sagittal plane and frontal plane in head posture without splint.

• Journal of the Korean Society of Industry Convergence
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• v.18 no.2
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• pp.99-109
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• 2015

This study proposes a new approach to analyze the impedance and the elasticity of a serial chain of spring-damper system, areal-time collision-free trajectory generation algorithm is proposed. The reference points on a trajectory connected by the spring-damper system have a mechanism for self-position adjustment to solve a collision problem by the impedance, and the local adjustment of each reference point is propagated through the elasticity to a real robot at the end of the spring-damper system. As a result, the overall trajectory consisting of the reference points becomes free of collision with environmental obstacles and efficient having the shortest distance as possible. In this process,, the reference points connected by the spring-damper system take role of virtual robot as global guidance for a real robot, and a cooperative is carried out by the system of robots. A control technology is proposed to implement for mobile robot.

• 제어로봇시스템학회:학술대회논문집
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• 1990.10b
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• pp.990-995
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• 1990

A minimum-time trajectory planning for two robot arms with designated paths and coordination is proposed. The problem considered in this paper is a subproblem of hierarchically decomposed trajectory planning approach for multiple robots : i) path planning, ii) coordination planning, iii) velocity planning. In coordination planning stage, coordination space, a specific form of configuration space, is constructed to determine collision region and collision-free region, and a collision-free coordination curve (CFCC) passing collision-free region is selected. In velocity planning stage, normal dynamic equations of the robots, described by joint angles, velocities and accelerations, are converted into simpler forms which are described by traveling distance along collision-free coordination curve. By utilizing maximum allowable torques and joint velocity limits, admissible range of velocity and acceleration along CFCC is derived, and a minimum-time velocity planning is calculated in phase plane. Also the planning algorithm itself is converted to simple numerical iterative calculation form based on the concept of neural optimization network, which gives a feasible approximate solution to this planning problem. To show the usefulness of proposed method, an example of trajectory planning for 2 SCARA type robots in common workspace is illustrated.

• International Journal of Control, Automation, and Systems
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• v.5 no.2
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• pp.184-191
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• 2007

Autonomous navigation of mobile robot requires a ranging system for measurement of distance to environmental objects. It is obvious that the wider and the faster distance measurement gives a mobile robot more freedom in trajectory planning and control. The active omni-directional ranging system proposed in this paper is capable of obtaining the distance for all 3600 directions in real-time because of the omni-directional mirror and the structured light. Distance computation including the sensitivity analysis and the experiments on the omni-directional ranging are presented to verify the effectiveness of the proposed system.

• Journal of Navigation and Port Research
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• v.47 no.6
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• pp.367-375
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• 2023

This study developed a new distance metric for vessel trajectories, applicable to marine traffic control services in the Korean coastal waters. The proposed metric is designed through the weighted summation of the traditional Hausdorff distance, which measures the similarity between spatiotemporal data and incorporates the differences in the average Speed Over Ground (SOG) and the variance in Course Over Ground (COG) between two trajectories. To validate the effectiveness of this new metric, a comparative analysis was conducted using the actual Automatic Identification System (AIS) trajectory data, in conjunction with an agglomerative clustering algorithm. Data visualizations were used to confirm that the results of trajectory clustering, with the new metric, reflect geographical distances and the distribution of vessel behavioral characteristics more accurately, than conventional metrics such as the Hausdorff distance and Dynamic Time Warping distance. Quantitatively, based on the Davies-Bouldin index, the clustering results were found to be superior or comparable and demonstrated exceptional efficiency in computational distance calculation.