• International Journal of Contents
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• v.10 no.4
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• pp.69-74
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• 2014

General location aware systems are only applied to indoor and outdoor environments using more than three transmitters to estimate a fixed object location. Those kinds of systems have environmental restrictions that require an already established infrastructure. To solve this problem, an Object Location Estimation (OLE) algorithm based on PTP (Point To Point) communication has been proposed. However, the problem with this method is that deduction of performance parameters is not enough and location estimation is very difficult because of unknown restriction conditions. From experimental tests in this research, we determined that the performance parameters for restriction conditions are a maximum transmission distance of CSS communication and an optimum moving distance interval between personal locations. In this paper, a system applied OLE algorithm based on PTP communication is implemented using a CSS (Chirp Spread Spectrum) communication module. A maximum transmission distance for CSS communication and an optimum moving distance interval between personal locations are then deducted and studied to estimate a fixed object location for generalization.

• Journal of Institute of Control, Robotics and Systems
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• v.14 no.8
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• pp.760-766
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• 2008

This paper proposes an efficient location technique to find an indoor location under the IEEE 802.11 wireless local area networks. The proposed method is based on the range measurements obtained from a simple radio frequency propagation model. Thus, unlike the radio frequency fingerprint correlation method, it does not suffer from the computational burden during the real-time location service period and can quickly reply the location requests of many users at the same time. To increase the location accuracy in spite of the frequent non-line-of-sight error occurrences, the proposed method calibrates the distortion of the non-line-of-sight error by a simple measurement surveying procedure that does not require the surveyor's manual interaction. Experimental results show the capability of the proposed method.

• Journal of Korea Society of Industrial Information Systems
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• v.18 no.6
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• pp.1-8
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• 2013

Recently, as increasing use of smartphone, the development of social network service(SNS) applications is very active because of the mobility of smartphone. In addition, as the demand of the location based service(LBS) supporting mobile information is expanded, LBS combined with SNS improves the usability of smart phones. This paper proposes the smartphone application that provides the information for SNS generated depending on the location, by tracking the user's location in real time.

• Journal of Institute of Control, Robotics and Systems
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• v.16 no.2
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• pp.158-163
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• 2010

In this paper, we propose the location measurement algorithm of unknown tag based on RFID (Radio-Frequency IDentification) by using RSSI (Received Signal Strength Indication) and TDOA (Time Difference of Arrival) and extended Kalman filter in smart space. To do this, first, we recognize the location of unknown tag by using the RSSI and TDOA recognition methods. Second, we set the coordinate of the tag location measured by using trilateration and SX algorithm. But the tag location data measured by this method are included complex environmental error. So, we use the extended Kalman filter in order to revise error data of the tag location. Finally, we validate the applicability of the proposed method though the simulation in a complex environment.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.52 no.1
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• pp.29-35
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• 2003

This paper presents a fault location algorithm when there are parallel circuits in power system networks. In transmission networks, a fault location method using the distribution factor of fault currents is introduced and in distribution networks a method using direct 3-phase circuit analysis is developed, because the distribution networks are unbalanced. The effect of parallel circuits in fault location is studied in this paper. The effect is important for the range of protecting zones of distance relay in transmission networks and fault location in distribution networks. The result of developed fault location algorithm shows high accuracy in the simulation that using the EMTP.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.46 no.4
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• pp.238-245
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• 2023

As technologies have been more quickly developed in this 4th Industry Revolution era, their application to defense industry has been also growing. With these much advanced technologies, we attempt to use Manned-Unmanned Teaming systems in various military operations. In this study, we consider the Location-Routing Problem for reconnaissance surveillance missions of the maritime manned-unmanned surface vehicles. As a solution technique, the two-phase method is presented. In the first location phase, the p-median problem is solved to determine which nodes are used as the seeds for the manned vehicles using Lagrangian relaxation with the subgradient method. In the second routing phase, using the results obtained from the location phase, the Vehicle Routing Problems are solved to determine the search routes of the unmanned vehicles by applying the Location Based Heuristic. For three network data sets, computational experiments are conducted to show the performance of the proposed two-phase method.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2003.09a
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• pp.191-194
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• 2003

Location-allocation problem is known as one of the important problem faced in Industrial Engineering and Operations Research fielde. There are many variations on this problem for different applications, however, most of them consider no obstacle existing. Since the location-allocation problem with obstacles is very complex and with many infeasible solutions, no direct method is effective to solve it. In this paper we propose a hybrid Genetic Algorithm (hGA) method for solving this problem. The proposed hGA is based on Lagrangian relaxation method and Dijkstra's shortest path algorithm. To enhance the proposed hGA, a Fuzzy Logic Controller (FLC) approach is also adopted to auto-tune the GA parameters.

• Journal of Computing Science and Engineering
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• v.4 no.2
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• pp.173-187
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• 2010

Recent technological advances in mobile communication systems have made explosive growth in the number of mobile device users worldwide. One of the most important issues in designing a mobile computing system is location management of users. The hierarchical systems had been proposed to solve the scalability problem in location management. The scalability problem occurs when there are too many users for a mobile system to handle, as the system is likely to react slow or even get down due to late updates of the location databases. In this paper, we propose a top-down clustering algorithm for hierarchical location database systems in a wireless network. A hierarchical location database system employs a tree structure. The proposed algorithm uses a top-down approach and utilizes the number of visits to each cell made by the users along with the movement information between a pair of adjacent cells. We then present a modified algorithm by incorporating the exhaustive method when there remain a few levels of the tree to be processed. We also propose a capacity constraint top-down clustering algorithm for more realistic environments where a database has a capacity limit. By the capacity of a database we mean the maximum number of mobile device users in the cells that can be handled by the database. This algorithm reduces a number of databases used for the system and improves the update performance. The experimental results show that the proposed, top-down, modified top-down, and capacity constraint top-down clustering algorithms reduce the update cost by 17.0%, 18.0%, 24.1%, the update time by about 43.0%, 39.0%, 42.3%, respectively. The capacity constraint algorithm reduces the average number of databases used for the system by 23.9% over other algorithms.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.10 no.7
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• pp.1295-1300
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• 2006

In this paper, we have developed RFID systems with integrated tag location data for efficient logistics information systems. These are consist of RFID readers with GPS module and RFID networks to service tag location data. The developed RFID readers can get location informations Of the tags, transfer them high speed by TCP/IP protocols, and operate as web servers. And we presented a simple service network system based on EPC network to service both location and tag data. The proposed system can be applicable to tracebility or finding locations of the products.

• Journal of Korean Institute of Industrial Engineers
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• v.24 no.4
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• pp.519-528
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• 1998

This paper examines the effect of storage location configurations on dual command cycle times for the efficient operation of automated storage/retrieval systems. We use a contour line approach to determine storage location configurations. We present a contour line configuration generating scheme and a location indexing scheme. Given a contour line configuration, the location indexing scheme provides a unique priority to each location. The location priority is then used for determining the storage location of an incoming load. To investigate the effect of alternative contour line configurations on dual command cycle times, we perform a series of experiments under various storage policies.