• Journal of IKEEE
• /
• v.26 no.4
• /
• pp.681-685
• /
• 2022

Including the COVID-19 crisis, humanity is constantly exposed to viral infections, and efforts are being made to prevent the spread of infection by quickly isolating infected people and tracing contacts. Passive epidemiological investigations that confirm contact with an infected person through contact have limitations in terms of accuracy and speed, so automatic tracking methods using various digital technologies are being proposed. This paper verify contact by utilizing Bluetooth Low Energy (BLE) technology and present an algorithm that identifies close contact through analysis and correction of RSSI (Received Signal Strength Indicator) values. Also, propose a system that can prevent the spread of viruses in a centralized server structure.

• Journal of Advanced Navigation Technology
• /
• v.13 no.6
• /
• pp.916-925
• /
• 2009

4S (Ship to Ship, Ship to Shore) communication is the key to strategic development of e-navigation, a core element of IT vessel convergence. 4S communication is intended to integrate and standardize various communication infrastructures on land and communication equipment complying with communication equipment equipped in ships. This paper aims to apply the Korean technology IEEE 802.16e adopted as an international standard, to replace and compensate for existing vessel communication media such as low speed HF/MF/VHF to the ocean environment. To this end, various experimental conditions between the coast station where a relay station was installed and related equipment equipped on a ship are set. Communication signals were monitored and the RSSI and CINR were measured. Based on experimental analysis and results, various challenges and solutions which may occur in ocean environment were sought, and communication availability was analyzed through transmission data throughput, at the maximum effective distance range of the signal. It was proven that high speed multimedia data could be exchanged for up to 20 km even among 80km kph ships moving around near the sea, ensuring that this technology could be applied to the ocean environment.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.18 no.10
• /
• pp.2523-2529
• /
• 2014

Location estimation service can be provided outdoors using various location estimation system based on GPS. However, location estimation system is based on existing indoor resources as GPS cannot be used because of insufficient visible satellites and weak signals. The fingerprinting technique that uses WLAN signal, in particular, is good to use indoors because it uses RSSI provided by AP to estimate location. However, its accuracy may vary depending on how accurate data the offline stage used where the fingerprinting map is built. The study sampled various data at the stage that builds the fingerprinting map and suggested a location estimation system that enhances its precision by saving the data of high frequency among them to improve this problem. The suggested location estimation system based on majority sampling data estimates location by filtering RSSI data of the highest frequency at the client and server to be saved at a map, building the map and measuring a similar distance. As a result of the test, the location estimation precision stood at minimum 87.5 % and maximum 90.4% with the margin of error at minimum 0.25 to 2.72m.

• Journal of Institute of Control, Robotics and Systems
• /
• v.19 no.2
• /
• pp.107-112
• /
• 2013

In this paper, we discuss a 3-dimensional localization sensor node using EM waves (Electromagnetic waves) with RSSI (Received Signal Strength Indicator). Generally EM waves cannot be used in underwater environment, because the signal is highly attenuated by the water medium according to the distance. Although the signal quickly reduces in underwater, the reducing tendency is very clear and uniform. Hence EM waves have possibility as underwater distance sensors. The authors have verified the possibility by theory and several experiments, and developed calibration methods in case of linear and planer environment. For 3-dimensional localization in underwater, it must be known antenna's radiation pattern property in electric plane(called E-plane). In this paper, we proceed experiments to verify attenuation tendency with z axis movement, PLF (Polarization Loss Factor) and ILF (Inclination Loss Factor) with its theoretical approach.

• Journal of Electrical Engineering and Technology
• /
• v.10 no.1
• /
• pp.436-442
• /
• 2015

In this paper, we develop an indoor localization device which embeds localization information into indoor light-emitting-diodes (LED) lighting systems. The key idea of our device is the use of the newly proposed "bit stuffing method". Through the use of stuff bits, our device is able to measure signal strengths even in transient states, which prohibits interference between lighting signals. The stuff bits also scatter the parts of the signal where the LED is turned on, thus provides quality indoor lighting. Additionally, for the indoor localization system based on RSSI and TDM to be practical, we propose methods for the control of LED lamps and compensation of received signals. The effectiveness of the proposed scheme is validated through experiments with a low-cost implementation including an indoor navigation task.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
• /
• 2013.04a
• /
• pp.50-51
• /
• 2013

화재발생시 기존의 비상경보설비는 화재경보라는 단순한 정보만을 제공함으로서 대피자의 입장에서는 건축물의 안전상황 및 피난상황을 식별할 수 없다. 따라서 화재발생시 대피자들이 밀집되는 병목현상이나 화재 영향에 노출되어 있는 피난경로로의 대피 등은 화재 피해를 가중시키고 있다. 본 연구의 목적은 현재 응용 가능한 대표적인 Ubiquitous 기술 중 개인의 위치를 식별하여 이용하는 위치인식기술 RSSI(Received Signal Strength Indication)을 활용한다. RSSI를 기반으로 한 LQI(Link Quality Indication)는 무선통신기간의 거리인식을 통해 대피자 정보 시스템 정보를 획득한다. 이러한 위치정보시스템을 응용하여 개발한 화재 안전 시스템은 화재 위치를 식별하고 화재위험 지역의 상황변화를 예측하여 피난경로 선정을 위한 안전정보를 제공하여 준다.

• Journal of Institute of Control, Robotics and Systems
• /
• v.13 no.10
• /
• pp.983-989
• /
• 2007

Most of life thing including human being have tendency of reaction with inherently their own pattern against environmental change caused by such as light, sound, smell etc. Especially, a sense of direction often works as a very important factor in such reaction. Actually, human or animal lift that can react instantly to a stimulus determine their action with a sense of direction to a stimulant. In this paper, we try to propose how to give a sense of direction to a robot using sound being representative stimulant, and tracking sensors being able to detect the direction of such sound source. We also try to propose how to determine the relative directions among devices or robots using the digital compass and the RSSI on wireless network.

• Proceedings of the KIEE Conference
• /
• 2011.07a
• /
• pp.1884-1885
• /
• 2011

In the wireless sensor network (WSN) environment, the approximate point-in-triangulation (APIT) is a kind of range-free localization algorithm. This algorithm provides high precision, however, the coverage rate is somewhat poor. In this paper, we propose an improved APIT algorithm for the localization of swarm robots, which is based on the received signal strength indicator (RSSI) and the center of gravity (COG) methods.

• Journal of the Korea Society of Computer and Information
• /
• v.21 no.10
• /
• pp.55-62
• /
• 2016

In this paper, we present indoor localization technologies using the bluetooth signal categorizing them into proximity based, triangulation based and fingerprinting based technologies. Then we provide localization accuracy improvement algorithms such as moving average, K-means, particle filter, and K-Nearest neighbor algorithms. We define important performance issues for indoor localization technologies and analyze recent technologies according to the performance issues. Finally we provide experimental results for correlation between RSSI and distance. We believe that this paper provide wise view and necessary information for recent localization technologies using the bluetooth signal.

• ETRI Journal
• /
• v.34 no.4
• /
• pp.625-628
• /
• 2012

In this letter, a novel method for localizing a user in a smart home environment is presented. We propose a two-level structure, in which the first level determines an occupant's location in the block level using RSSI in a ZigBee network, while the second level accurately estimates the occupant's location using a particle filter to handle the variations in the signal strength measurement. We devise an experimental setup with people performing significant tasks in the smart home. The results obtained from the testbed indicate that the proposed model leads to an improvement in the mean distance error.