• Journal of Institute of Control, Robotics and Systems
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• v.17 no.5
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• pp.429-435
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• 2011

This paper presents a sensor fusion-based estimation of heading and a Bezier curve-based motion planning for unmanned ground vehicle. For the vehicle to drive itself autonomously and safely, it should estimate its pose with sufficient accuracy in reasonable processing time. The vehicle should also have a path planning algorithm that enables to adapt to various situations on the road, especially at intersections. First, we address a sensor fusion-based estimation of the heading of the vehicle. Based on extended Kalman filter, the algorithm estimates the heading using the GPS, IMU, and wheel encoders considering the reliability of each sensor measurement. Then, we propose a Bezier curve-based path planner that creates several number of path candidates which are described as Bezier curves with adaptive control points, and selects the best path among them that has the maximum probability of passing through waypoints or arriving at target points. Experiments under various outdoor conditions including at intersections, verify the reliability of our algorithm.

• Physical Therapy Korea
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• v.23 no.3
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• pp.40-47
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• 2016

Background: Assessments of Sit-to-Stand (STS) and gait functions are essential procedures in evaluating level of independence for the patients after stroke. In a previous study, we developed the software to analyze center of pressure (COP) in standing position on Wii Balance Board (WBB). Objects: This purpose of this study is to measure test-retest reliability of ground reaction forces, COP and time using WBB on STS and gait in healthy adults. Methods: Fifteen healthy participants performed three trials of STS and gait on WBB. The time (s), vertical peak (%) and COP path-length (cm) were measured on both tasks. Additionally, counter (%), different peak (%), symmetry ratio, COP x-range and COP y-range were analyzed on STS, 1st peak (%), 2nd peak (%) of weight were analyzed on gait. Intra-class correlation coefficient (ICC), standard error measurement (SEM) and smallest real difference (SRD) were analyzed for test-retest reliability. Results: ICC of all variables except COP path-length appeared to .676~.946 on STS, and to .723~.901 on gait. SEM and SRD of all variables excepting COP path-length appeared .227~8.886, .033~24.575 on STS. SEM and SRD excepting COP path-length appeared about .019~3.933, .054~11.879 on gait. Conclusion: WBB is not only cheaper than force plate, but also easier to use clinically. WBB is considered as an adequate equipment for measuring changes of weight bearing during balance, STS and gait test which are normally used for functional assessment in patients with neurological problems and elderly. The further study is needed concurrent validity on neurological patients, elderly patients using force plate and WBB.

• Journal of Gifted/Talented Education
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• v.25 no.4
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• pp.511-528
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• 2015

The development process from creative potential to realized talent is complex and non-linear. This feature of the process stands out more in the process of living a creative life in the long-term rather than in a situation to solve certain problems in the short-term. The purpose of this study is to develop Creativity Path Inventory (CPI) for undergraduate students based on Sawyer's Zigzag Model which is one of creative process theories and to verify reliability and validity of the inventory. Thus, reflecting the characteristics of each stage of the model, this study developed 88 items in 8 factors and finally confirmed 38 items in 7 factors through item analysis and verification process on construct validity. Internal consistency of a total of 38 items in CPI turned out to be .835, confirming the reliability of the inventory and goodness-of-fit index of the final model also demonstrated an appropriate result. CPI with verified reliability and validity will help enable people who want to manifest creativity in view of everyday creativity to realize self-improvement by self-reporting their strengths and weaknesses on their own.

• Journal of the Korean Operations Research and Management Science Society
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• v.33 no.2
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• pp.103-114
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• 2008

Overlay Multicast is a promising approach to overcome the implementation problem of IP multicast. Real time services like Internet broadcasting are provided by the overlay multicast technology due to the complex nature and high cost of IP multicast. To reduce frequent updates of multicast members and to support real time service without delay, we suggest a reliable overlay multicast tree based on members' sojourn probabilities. Path reliabilities from a source to member nodes are considered to maximize the reliability of an overlay multicast tree. The problem is formulated as a binary integer programming with degree and delay bounds. A tabu search heuristic is developed to solve the NP-complete problem. Outstanding results are obtained which is comparable to the optimal solution and applicable in real time.

• Proceedings of the Korean Reliability Society Conference
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• 2002.06a
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• pp.297-302
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• 2002

An efficient method is developed to obtain the maximum capacity flow for a network when its simple paths are known. Most of the existing techniques need to convert simple paths into minimal cuts, or to determine the order of simple paths to be applied in the process to reach the correct result. In this paper, we propose a method based on the concepts of signed simple path and signed flow defined in the text. Our method involves a fewer number of arithmetic operations at each iteration, and requires fewer iterations in the whole process than the existing methods. Our method can be easily extended to a mixed network with a slight modification. Furthermore, the correctness of our method does not depend on the order of simple paths to be applied in the process.

• Journal of Internet Computing and Services
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• v.7 no.6
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• pp.175-183
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• 2006

An ad-hoc network is a group of mobile nodes acting as routers. The of hoc node has a precondition of mobility, allowing path to be easily disconnected when transmitting data, thereby increasing network overhead. However, most of hoc routing protocols set up the path based only on the number of hops without considering other practical factors. Here we consider a path with the least substantial number of transmission (SNT) from source to destination based on reliabilities of links. This includes retransmissions due to unreliable links. In this paper, an efficient ad-hoc link reliability based routing (PU) protocol suitable for mobile ah-hoc network in terms of SNT, is proposed. The network overhead and data transmission delay ore reduced, by considering both ad-hoc link reliability and the number of hops. Our empirical performance evaluation comparing to AODV (8) shows that the enhancement is up to about 31% for SNT depending upon the mobility of nodes.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2006.11a
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• pp.312-315
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• 2006

Overlay Multicast is a promising approach to overcome the implementation problem of IP multicast. Real time services like internet broadcasting are provided by overlay multicast technology due to the complex nature of IP multicast and the high cost to support multicast function. Since multicast members can dynamically join or leave their multicast group, it is necessary to keep a reliable overlay multicast tree to support real time service without delay. In this paper, we consider path level reliability that connects each member node. The problem is formulated as a binary integer programming which maximizes the reliability of multicast tree. Tabu search based algorithm is presented to solve the NP-hard problem.

• Journal of the Korea Institute of Military Science and Technology
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• v.10 no.2
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• pp.107-114
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• 2007

This paper describes the Petri Net(PN) model for reliability analysis of fault-tolerant dual Ethernet which Is applied in Naval Combat System. The network for Naval Combat System performs failure detection and auto path recovery by handling redundant path in case of temporary link failure. After studying the behavior of this kind of network, the reliability analysis model is proposed using stochastic Petri Net and continuous-time Markov chains. Finally, the numerical result is analyzed according to changing the failure rate and the recover rate of link.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.24 no.63
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• pp.33-43
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• 2001

To estimate the reliability of a large and complex network with a small variance, we propose two dynamic Monte Carlo sampling methods: the sequential minimal cut set (SMCS) and the sequential minimal path set (SMPS) methods. These methods do not require all minimal cut sets or path sets to be given in advance and do not simulate all arcs at each trial, which can decrease the valiance of network reliability. Based on the proposed methods, we develop the importance sampling estimators, the total hazard (or safety) estimator and the hazard (or safety) importance sampling estimator, and compare the performance of these simulation estimators. It is found that these estimators can significantly reduce the variance of the raw simulation estimator and the usual importance sampling estimator. Especially, the SMCS algorithm is very effective in case that the failure probabilities of arcs are low. On the contrary, the SMPS algorithm is effective in case that the success Probabilities of arcs are low.

• Journal of the Korean Data and Information Science Society
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• v.16 no.1
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• pp.1-11
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• 2005

A network consisting of a set of N nodes and a set of links is considered. The nodes are assumed to be perfect and the states of links to be binary and associated to each other. After defining a network structure function, which represents the state of network as a function of the states of links, we obtain some lower and upper bounds on the network reliability by adopting minmax principle and minimal path and cut set arguments. These bounds are given as functions of the reliabilities of links. The bridge network is considered as an example.