• The Journal of the Korea Contents Association
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• v.9 no.11
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• pp.90-99
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• 2009

This paper presents the implementation of RFID EPC global network educational system based on using 900MHz air interface between the reader and the active tag. The software of reader and the active tag is developed on embedded environment, and the software of PC controlling the reader is based on window OS operated as the server. The ATmega128 VLSI chip is used for the processor of the reader and the active tag. As the development environment, AVR compiler is used for the reader and the active tag of which the programming language is C. The visual C++language of the visual studio on the PC activated as the server is used for development language. Main functions of this system are to control tag containing EPC global Data by PC through the reader, to obtain information of tag through the internet and to read/write data on tag memory. Finally the data written from the active tag's memory is sent to the PC via the reader as "read" operation and compare the received data with one already sent to the tag. Software implementation of 900MHz EPC global RFID educational system is done on the basis of these functions.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.48 no.2
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• pp.21-28
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• 2011

We consider an RFID network configured as a star in which tags stationarily move into and out of the vicinity of the reader. To cognize the neighboring tags in the RFID network, we propose a scheme based on dynamic framed and slotted ALOHA which determines the number of slots belonging to a frame in a dynamic fashion. The tag cognizance scheme distinctively employs a rule for estimating the expected number of neighboring tags, identified as R-retrospective maximum likelihood rule, where the observations attained in the R previous frames are used in maximizing the likelihood of expected number of tags. Simulation result shows that a slight increase in depth of retrospect is able to significantly improve the cognizance performance.

• Journal of Institute of Control, Robotics and Systems
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• v.12 no.10
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• pp.968-974
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• 2006

We are moving into the era of ubiquitous computing. Ubiquitous Sensor Network (USN) is a base of such computing paradigm, where recognizing the identification and the position of objects is important. For the object identification, RFID tags are commonly used. For the object positioning, use of sensors such as laser and ultrasonic scanners is popular. Recently, there have been a few attempts to apply RFID technology in robot localization by replacing the sensors with RFID readers to achieve simpler and unified USN settings. However, RFID does not provide enough sensing accuracy for some USN applications such as robot navigation, mainly because of its inaccuracy in distance measurements. In this paper, we describe our approach on achieving accurate navigation using RFID. We solely rely on RFID mechanism for the localization by providing coordinate information through RFID tag installed floors. With the accurate positional information stored in the RFID tag, we complement coordinate errors accumulated during the wheel based robot navigation. We especially focus on how to distribute RFID tags (tag pattern) and how many to place (tag granularity) on the RFID tag-floor. To determine efficient tag granularities and tag patterns, we developed a simulation program. We define the error in navigation and use it to compare the effectiveness of the navigation. We analyze the simulation results to determine the efficient granularities and tag arrangement patterns that can improve the effectiveness of RFID navigation in general.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.16 no.2
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• pp.81-94
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• 2006

This study, in particular, aims to regulate the core techniques of ubiquitous computing, such as the use of an ad hoc network and the smart-tag technique, and to look more closely into RFID Tag's smart-tag-related security service. The study aims to do so because several important technical factors and structures must be taken into account for RFID Tag to be applied in the ubiquitous-computing-related infrastructure, and the security of the tag is considered one of the core technologies. To realize secure ubiquitous computing in the case of the Passive-tag-Performing RF communication, a less costly security service, the technical items needed to carry this out, a security service to be applied to passive tags, and network management techniques are required. Therefore, the passive-tag-based networks as the authentication level is established based on the secure authentication of each tag and the service that the tag delivers in the passive-tag-based networks and as the same service and authentication levels are applied, and the active-tag-based network system proposed herein is not merely a security service against illegal RFID tags by performing a current-location and service registration process after the secure authentication process of the active RFID tag, but is also a secure protocol for single and group services, is proposed in this study.

• The Journal of the Korea institute of electronic communication sciences
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• v.11 no.6
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• pp.581-590
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• 2016

This paper proposes an efficient collision avoidance algorithm that a group of RFID readers manage each of their affiliated active RFID tags in a space by establishing wireless network and avoids communication collision between RFID reader to reader and RFID tag to tag, and reader to tag. RF readers operate as wireless network nodes, create synchronous links each other, and can exchange messages. Active tags also are operated communicating each reader devices synchronously, and competing slot position between tags algorithm using unique tag identification number is implemented. Each reader node operates their own reader function different time slot network communication period to prevent collision between readers communication.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.11B
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• pp.1272-1282
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• 2009

This paper consists of two parts: the protocol for tag-to-tag mesh network and the implementation of dual-radio RFID system. Recently, RFID has been adopted in ports or warehouse, being attached to containers and palettes for loading/unloading automation. However, the RFID system has encountered one problem - some tags cannot receive any command from reader intermittently due to signal interference by containers or field equipments (e. g. cranes and yard tractors). This area where reader signal cannot reach is called dead-zone. The proposed method for solving the dead-zone problem is as follows. A zone which can be communicated directly between readers and tags communicates in 433MHz frequency band in compliance with ISO/IEC 18000-7 standard. On the other hand, dead-zone communicates in 2.4GHz frequency band by using tag-to-tag mesh network in compliance with IEEE 802.15.4 standard. The proposed method can not only save much cost to install additional readers but also help resolve the dead-zone problem. Furthermore, it can provide the easier, faster, and more economical network infrastructure.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.1 s.116
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• pp.31-36
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• 2007

In the RFID system, one of the important criteria of tag antenna performance is the detection distance. The most important factor determining the detection distance of the tag antenna is the Radar Cross Sections(RCS). In this paper, we propose a method to simply measure the RCS of the RFID tag antenna using two reader antennas(Tx and Rx) and a network analyzer. We estimate RCS' from the RCS equation based on the measured $S_{21}$ using the network analyzer. We compare the measured $S_{21}$ values with the calculated $S_{21}$ values and the simulated $S_{21}$ values using EM simulator. The used tag antennas are two kinds of dipole-type, metal-type, and an inductively-coupled type ones. In case of the dipole type, the measured, simulated and calculated values of the RCS are almost the same. In case of other types, we obtain the measured RCS values with a difference of about 3 dB.

• 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 the Institute of Electronics Engineers of Korea TC
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• v.45 no.5
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• pp.12-20
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• 2008

RFID(Radio frequency indentification) technology, that the reader detect the tag information attached on the objects without contact, is considered the kernel of realizing tile Ubiquitous Sensor Network. Particularly, because there are lots of tags(which the reader have to detect) in the UHF RFID system(that is applied at the Logistic & Distribution industry). In the UHF RFID system the negative effects, we called the tag-collision, may occur and we should solve these effects. So, in the EPCglobal Gen2 protocol they present the Slotted Random Anti-collision algorithm to prevent the tag-collision effect. In this paper, in order to minimize the tag-collision effect and bring on the system efficiency, we propose the Power Increasing Method that controls the transmission power of the reader depending on the environment and verily the improved performance.

• Journal of the Korea Society of Computer and Information
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• v.11 no.5 s.43
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• pp.211-221
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• 2006

Manufacturing Execution System(MES) immediately enables users to share the information of systems industrywide, efficiently manages synthetic information with data collection through treating the data in a fast way, and helps their decision-making. MES for real-time information processing requires certain conditions such as data modeling of RFID, which has recently attracted attentions, and monitoring of each product unit from manufacture to sales. However, in the middle of processing the unit with a RFID tag, transponders(readers) can't often read the tag due to reader's malfunctions, intentional damages, loss and the circumstantial effects; for that reason, users are unable to confirm the location of the product unit. In this case, users cannot avoid tracing the path of units with uncertain clues. In this paper we suggest that the unique MES based on RFID and Bayesian Network can immediately track the product unit, and show how to evaluate it.