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

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.38A no.3
• /
• pp.277-288
• /
• 2013

3GPP LTE-Advanced (Third Generation Partnership Project Long Term Evolution-Advanced) as a next generation mobile communication standard introduced small base stations such as femto cells or pico cells, and D2D (Device-to-Device) communications between mobiles in the proximity in order to satisfy the needs of rapidly growing wireless data traffic. A diverse range of topics has been studied to solve various interference situations which may occur within a single cell. In particular, an introduction of a small base station along with D2D communication raises important issues of how to increase the channel capacity and frequency efficiency in HetNets (Heterogeneous Networks). To this end, we propose in this paper methods to manage the interference between the macro cell and other small cells in the HetNet to improve the frequency efficiency. The proposed CCN (Cluster Coordinator Node)-assisted ICI (Inter-Cell Interference) avoidance methods exploit the CCN to control the interference in HetNet comprising of an MeNB (Macro enhanced Node-B) and a large number of small cells. A CCN which is located at the center of a number of small cells serves to avoid the interference between macro cell and small cells. We propose methods of resource allocation to avoid ICI for user equipments within the CCN coverage, and evaluate their performance through system-level computer simulations.

• The Journal of the Korea Contents Association
• /
• v.9 no.8
• /
• pp.64-72
• /
• 2009

AMR(Automatic Meter Reading), which means that it reads the meter of electricity, gas, or water, etc at a remote place automatically through wired or wireless communication, has been studied in terms of Power Line Communication method and Local Area Wireless Communication method, etc. In this paper, we designed and implemented JCA(Java Card for AMR) capable of AMR, which is based on java Card technology indispensable to the ubiquitous world. In this paper, JCA follows standard transactional procedures offered by power supply company and manages power usage log and billing data, and is designed in order to satisfy EMV multi-functional specifications. Because JCA is a multi-functional smart card capable of post-issuance applets as an open platform, it is installed into other applications of affiliated concerns as well as credit card and traffic card applications. Not only the proposed JCA is a low cost system, compared to other AMR systems, but is capable of paying rates in advance or later by applying authentication and security function of java Card. In addition the proposed JCA system can create value added services such as affiliated services with corporate alliance.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.30 no.5B
• /
• pp.479-486
• /
• 2010

Reliable hydrologic data acquisition is the basic and essential requirement for efficient water management. Especially the acquisition of various stream data in a certain location is very important to construct on alarm system to response an urban flood which occurs frequently due to the effect of climate change. Although the frequency of stream inundation flood occurrence becomes low owing to the consistent stream improvement, the urban flood due to the drainage system problems such as deterioration and bad management occurs continuously. The consistent management and current status understanding of the urban drainage system is essential to reduce the urban flood. The purpose of this study is to develop the urban runoff network flow velocity monitoring system which has the capability of collecting stream data whenever, wherever and to whomever without expert knowledge using Code Division Multiple Access technique and Bluetooth near-distance wireless communication technique. The urban runoff network flow velocity monitoring system consists of three stages. In the first stage, the stream information obtained by using ubiquitous floater is transferred to the server computer. In the second stage, the current state of the urban drainage system is assessed through the server computer. In the last stage, the information is provided to the user through a GUI. As a result of applying, the developed urban runoff network flow velocity monitoring system to Woncheon-Stream in Suwon, the information necessary for urban drainage management can be managed in real time.

• Journal of Digital Convergence
• /
• v.11 no.2
• /
• pp.257-262
• /
• 2013

In mobile market which has been developed drastically, short distance mobile Near Field Communication is becoming the conversation topic. Google adopted this NFC technology to Android 플랫폼 for securing the leadership and many another countries including domestic companies are putting spurs to develop service and technology by connecting mobile carrier and the financial. Within this circumstance, most noticeable issue is securing stability of nfc application service. Android 플랫폼 is operating system of mobile device and also a software stack which is required limited hardware and immediate response. However, since its structural characteristic which is suitable for limited hardware, the response is not quite stable for real time process. That is, this paper researches by analyzing real time response of NFC related library provided from Android 플랫폼 and applying the result to NFC application for securing stable data process and response.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.14 no.7
• /
• pp.3431-3436
• /
• 2013

Band-notched ultra-wideband (UWB) antennas using frequency selective surfaces (FSSs) are presented. The proposed antennas utilized the band rejection characteristic of typical FSS unit cells. We loaded the FSS unit cells on the same plane of planar UWB antenna. These antennas are designed to reject the interference from the wireless local area network band, 5.15-5.825 GHz in the UWB band, 3.1-10.6 GHz. The measured peak gains of the proposed antennas are more than 2 dBi at both operation edge and center frequencies, and sufficient to apply for commercial purpose. The antennas are small size and planar shape for the purpose of the small mobile application, and enhanced design freedom by using various existing FSS unit cells.

• The Journal of the Korea Contents Association
• /
• v.16 no.8
• /
• pp.202-208
• /
• 2016

The scope of activities of the visually impaired is increasing. But they are not easy to visit the destination safely because the building was complicated and larger than ever. There is a guide system for visually impaired such as GPS and Audio alerts, Braille guide block, Acoustic signaller, etc. But they are not suitable for indoor because most of them are the outdoor guide system. Therefore, in this paper, I propose a system that provides guidance information to the visually impaired using Voice Technology, TTS (Text to Speech) and Haptic Technology, Beacon based on the wireless sensor networks. It informed the visually impaired of guidance information about destination such as distance, height, and obstacle to the destination using the generalized smart phone. The user could be received guide info about searches for the optimal route to the destination using the TTS technology and Haptic technology in test result of the proposed system.

• 한국HCI학회:학술대회논문집
• /
• 2008.02a
• /
• pp.280-285
• /
• 2008

ZigBee is Low Power and Low Data Rate Wireless Communication protocol. It apply to much Ubiquitous Sensor Network. ZigBee PAN is two type PAN. One is Beacon Enabled PAN, the other is Non Beacon Enabled PAN. To support Low Power in Non Beacon Enabled PAN, End-Device enter Active status at End-Device's wishing time and send a data. So, Router does not know End-Device sends a data time. To solving this problem, Router must always exist to Active status. In this case, Router receive a power supply always in Non Beacon Enabled PAN. But Router does not receive a power supply always, Router can not normal operation, such as Router use a battery. To solve this problem, Router will be support low power. In this paper, we will present Router's Low Power Algorithm. And we suggest 'PAN Time'. Device use 'PAN Time' for PAN synchronous. Router using Low Power Algorithm can be enter to inactive status. So Non Beacon Enabled PAN of Router support the low power mode Therefore Router does not receive a power supply always, Router can normal operation.

• Journal of the Institute of Electronics and Information Engineers
• /
• v.50 no.10
• /
• pp.31-40
• /
• 2013

In this paper, the spatial modulation (SM) multi-input multi-output (MIMO) system is proposed for indoor wireless local area networks (WLANs) with improved spectral efficiency. SM is suitable for high speed WLANs with avoiding the inter channel interference (ICI). Only one transmit antenna is activated in SM at each symbol interval. Therefore, it fails to attain the maximum coding gain of MIMO. The space time block code (STBC)-SM MIMO system can attain the maximum diversity gain at the expense of spectral efficiency. The proposed Golden-SM MIMO system uses the Golden code to improve the coding gain and spectral efficiency at the same time. The Golden code is adapted for STBC-SM and it makes the new code book for transmission symbols. The performance of the proposed system is compared with the conventional systems with computer simulations.

• Journal of Fashion Business
• /
• v.20 no.1
• /
• pp.142-156
• /
• 2016

Convergence of IT devices and fashion is enabling the industry to take fully different approaches in various areas including product planning, fabric selecting, distributing, and marketing. At the same time, it also transforms the definition of clothing itself. Convergence of IT technologies in the realm of fashion and textiles industries can create a powerful synergy through connection digital devices, such as mobile phone. In this context, this study attempts to suggest how IT technology can be efficiently harnessed through the usage of mobile devices in the planning stage of fashion materials, where the initial production plan of a clothing item is mapped out. This study ultimately aims to enhance the effectiveness of databases on fashion material information by using mobile devices to utilize NFC, an RFID technology having as much revolutionary power as Internet - which can be the convergence between IT and fashion across the software dimensions. To pursue this research, data on fashion material information regarding 200 woven fabric specimens were provided by textile companies. The information includes elements such as its composition, weight, width, yarn, density and sales report. These pieces of information were organized into a database. Drawing on this data, Android-based applications that allow smart phones to read off fabric information from NFC tags were developed for this study using two methods. The system works as follows: 1. NFC tag stickers are attached onto the hangers where 200 fabric samples are hanging. 2. The NFC tag stickers are tagged, or read off from a smart phone that support NFC functions. 3. Upon tagging, the Smart phone swiftly displays all information available on its screen - not only the aforementioned six elements, but also the image of the clothing item from the fabric in its finalized product form, and the video of the model wearing the item - for convenient view. The method harbors immense potential for the fashion industry in general, and will also be useful in those fields inside the industry that harness NFC technology.