• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.12 no.3
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• pp.89-97
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• 2012

In recent years, efficient energy management technologies are required, as environmental problems have emerged worldwide. In response to this, smart home services focused on efficient energy management technology seems to be emerging. And the integration of technology of user-oriented real-time energy monitoring and control systems is required. In this paper, we present a location-based green home service using smart phones for efficient energy management in a house. We design a green home network system to apply the green home service, and implement an integrated gateway system which connects and controls each appliance in a house. We develop appliance control services and indoor location services on smart phones, and determine whether user's occupancy of each room by measuring the location according to the variation of signal strength. In order to evaluate the performance of the energy savings, we have set up the scenarios of energy usage pattern and have compared the energy variation resulting from the application of the indoor location services with smart meters. A comparison of energy usage demonstrated that the energy saving of a house with the proposed location-based green home service was down up to 30%.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.1B
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• pp.162-175
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• 2010

Currently, geographical information is interpreted and adopted in a wide range of context, and used for meeting diverse demands, such as, battlefield, traffic management, or public safety. With such an explosive increase of location-based applications, a considerable amount of research on the localization technique has been carried out. Among them, RSS (Received Signal Strength)-based approach is used especially for the indoor localization due to intrinsic limitations of the indoor environment. In this paper, we perform theoretical and empirical studies on enhancing the accuracy of the RSS-based localization on the IEEE 802.15.4 network. To this end, we set up an indoor testbed and implement a localization system on it. In addition to the theoretical analysis of the localization algorithm that we used, an empirical analysis on the effect of the factors which affect the accuracy of a localization system is carried out. Finally, we suggest some critical guidelines that should be considered for building a highly accurate localization system.

• Smart Media Journal
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• v.12 no.4
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• pp.41-46
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• 2023

UWB is a type of technology used for indoor positioning and is characterized by higher accuracy than RSSI-based schemes. Mobile equipment operating based on ROS can monitor the environment around the equipment using lidar and cameras. When applying the loop closing technique to determine the starting position in this monitoring process, the existing method has a problem of low accuracy because the closing operation occurs only when there are feature points on the image. In this paper, to solve this problem, we designed a system that increases the accuracy of loop closing work by providing location information by mounting a UWB tag on a mobile device. In addition, the accuracy of the UWB-based indoor positioning system was evaluated through experiments, and it was verified that it could be used for loop closing techniques.

• Journal of Korea Multimedia Society
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• v.12 no.1
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• pp.156-167
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• 2009

Computing environment is evolving rapidly to ubiquitous environment. It thus makes people access and utilize any resource on the move and makes location of objects rise to the rank of the most important information. However provision of location information is too restrictive in small environments such as a home or building. In this paper we propose a home entertainment system which supports user mobility based on sensor networks and distributed devices. The proposed system estimates a user location by using signal strength received from Bluetooth ad-hoc networks. This estimated location information can tell which device a user can take advantage of while moving. In order to prove possibility of user mobility support, the system is implemented on our UPnP A/V framework home entertainment system to provide content streaming and the result shows that a provision of service for mobile users could be possible in small ubiquitous computing environments.

• Proceedings of the KSRS Conference
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• 2007.10a
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• pp.564-567
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• 2007

GPS(Global Positioning System) data has a high accuracy at outdoor positioning generally, but its accuracy decreases in the urban areas with dense buildings. Moreover insufficient number of satelllites prevent us GPS positioning at inside of buildings. To complement these shortcomings of GPS, RFID(Radio Frequency IDentification) has been studied on indoor positioning parts. In Ubiquitous environment, LBS(Location Based Service) which can be used anytime and anywhere is an essential component. We use kalman filter to estimate the real location in GPS and RFID handover area. This study's purpose is to make a continuous positioning system using interlocking RFID and GPS.

• Journal of the Korea Safety Management & Science
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• v.13 no.2
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• pp.147-155
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• 2011

For an effective energy management in intelligent buildings it is necessary to gather information about position/absence of people and the level of population. In this paper the smart occupancy detection system based on the active RFID is developed to satisfy such a demand. The performance of the developed system is tested and verified through various experiments. Furthermore the feasibility test of the active RFID tag is performed to verify whether it can be used as a location-based occupancy sensor. The developed core technology can be also applied to other fields such as security, healthcare, smart home, etc.

• IEMEK Journal of Embedded Systems and Applications
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• v.19 no.1
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• pp.39-46
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• 2024

In this paper, we propose an efficient method for estimating the number of people and their locations using multiple IR-UWB radar sensors. Using three IR-UWB radar sensors in the indoor space, the measured signal from the target is processed to remove the clutter using rejection methods. Then, to further remove the clutter and to determine the presence of the human, the time-frequency image representing the micro-Doppler is obtained and classified by a convolutional neural network. Finally, the system finds the number of human objects and estimates each position in a two-dimensional space. In experiments using the measured data, the system successfully estimated the location and number of individuals with a high accuracy ≈ 88.68 %.

• Journal of Institute of Control, Robotics and Systems
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• v.20 no.11
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• pp.1098-1102
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• 2014

Localization of aerial vehicles and map building of flight environments are key technologies for the autonomous flight of small UAVs. In outdoor environments, an unmanned aircraft can easily use a GPS (Global Positioning System) for its localization with acceptable accuracy. However, as the GPS is not available for use in indoor environments, the development of a SLAM (Simultaneous Localization and Mapping) system that is suitable for small UAVs is therefore needed. In this paper, we suggest a vision-based SLAM system that uses vision sensors and an AHRS (Attitude Heading Reference System) sensor. Feature points in images captured from the vision sensor are obtained by using GPU (Graphics Process Unit) based SIFT (Scale-invariant Feature Transform) algorithm. Those feature points are then combined with attitude information obtained from the AHRS to estimate the position of the small UAV. Based on the location information and color distribution, a Gaussian process model is generated, which could be a map. The experimental results show that the position of a small unmanned aircraft is estimated properly and the map of the environment is constructed by using the proposed method. Finally, the reliability of the proposed method is verified by comparing the difference between the estimated values and the actual values.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.1
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• pp.786-791
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• 2021

In this paper, in order to minimize limitations such as signal interference and positioning errors in existing indoor positioning systems, a smart LED-based positioning system for excellent line-of-sight radio environments and precise location tracking is proposed to improve accuracy. An IEEE 802.4 Zigbee module is mounted on the SMPS board of a smart LED; RSSI and LQI signals are received from a moving tag, and the system is configured to transmit the measured data to the positioning server through a gateway. For the experiment, the necessary hardware, such as the gateway and the smart LED module, were separately designed, and the experiment was conducted after configuring the system in an external field office. The positioning error was within 70cm as a result of performing complex calculations in the positioning server after transmitting a vector value of the moving object obtained from the direction sensor, together with a signal from the moving object received by the smart LED. The result is a significantly improved positioning error, compared to an existing short-range wireless communications-based system, and shows the level at which commercial products can be implemented.

• Journal of KIISE
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• v.42 no.2
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• pp.264-271
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• 2015

The general way to use a triangulation method is based on PTMP communication between an object and wireless modules in an environment, which is established by more than three wireless modules, to recognize the location of an object. Thus, this method has a problem that the PTMP-based system can only be applied in an environment where the wireless infra is already established. In order to solve this problem, the PTP communication schemes have been proposed but they are insufficient to generalize because they lack specific verification. In this paper, problems of an existed location estimation algorithm based on PTP communication are analyzed, and we propose a location estimation algorithm of a fixed object that satisfyies the condition of a single receiver being substituted to multiple receivers. A location estimation system we designed and implemented using CSS wireless communication modules to evaluate the proposed algorithm. We verify, by experimental results, that the optimum moving interval for the location estimation is 3m in indoor environment of $10m{\times}16m{\times}1m$.