• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.7B
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• pp.686-693
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• 2009

In this paper, we propose an efficient tag sleep method utilizing empty time slots for improving the tag collection performance in active RFID systems. In the proposed tag sleep method, the reader detects the occurrence of empty time slots by carrier sensing and utilizes the wasted empty time slots to transmit sleep commands to the collected tags throughout the framed slotted aloha-based tag collection process, resulting in reducing the time required for tag collection. Via the simulation experiments, we evaluated the performance of the tag collection applied with the proposed tag sleep method, compared with that of the basic tag collection. The simulation results showed that the tag collection applied with the proposed tag sleep method could reduce the average tag collection time by 12.28%, 12.30%, and 13.31 %, for the framed slotted aloha with the fixed 128 time slots and 256 time slots, and the dynamic framed slotted aloha anticollision protocols, respectively.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.15 no.5
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• pp.25-33
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• 2005

We propose a method to protect the tag's information from illegal reader in RFID system. In this method, a special tag called ownership tag makes intentionally collisions during singulation. By the forced collision of an ownership tag a reader can obtain the information of ordinary tags. Whereas a reader can not find my information on tag's ID without the ownership tag.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2011.10a
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• pp.231-234
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• 2011

Recently, the smart RFID tag technology which can measure external changing environment is globally interesting. In this paper, development of the Smart RFID tag using temperature sensor was represented. Smart RFID tag is basically comprised of antenna which has its bandwidth of 13.56Mhz, temperature sensors and data processing controller. Antenna design and smaller PCB production can be used to agri-food wrap. Since the smart RFID tag is distributed as an attachment to agri-food wrap, consumer can check temperature changes in the distribution process. Because temperature change check in real time, food confirm the status of transportation and the freshness. Also, smart RFID tag can be applied to proposed smart refrigerator.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.1 no.1
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• pp.19-31
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• 2007

RFID tag is detected by an RFID antenna and information is read from the tag detected, by an RFID reader. RFID tag detection by an RFID reader is very important at the deployment stage. Tag detection is influenced by factors such as tag direction on a target object, speed of a conveyer moving the object, and the contents of an object. The water content of the object absorbs radio waves at high frequencies, typically approximately 900 MHz, resulting in unstable tag signal power. Currently, finding the best conditions for factors influencing the tag detection requires very time consuming work at deployment. Thus, a quick and simple RFID tag detection scheme is needed to improve the current time consuming trial-and-error experimental method. This paper proposes a back-propagation learning-based RFID tag detection prediction scheme, which is intelligent and has the advantages of ease of use and time/cost savings. The results of simulation with the proposed scheme demonstrate a high prediction accuracy for tag detection on a water content, which is comparable with the current method in terms of time/cost savings.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.46 no.5
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• pp.70-77
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• 2009

In an RFID network consisting of a single reader and many tags, a framed and slotted ALOHA, which provides a number of slots for the tags to respond, was introduced for arbitrating a collision among tags' responses. In a framed and slotted ALOHA, the number of slots in each frame should be optimized to attain the maximal efficiency in tag cognizance. While such an optimization necessitates the knowledge about the number of tags, the reader hardly knows it. In this paper, we propose a tag cognizance scheme based on framed and slotted ALOHA, which is characterized by directly taking a Bayes action on the number of slots without estimating the number of tags separately. Specifically, a Bayes action is yielded by solving a decision problem which incorporates the prior distribution the number of tags, the observation on the number of slots in which no tag responds and the loss function reflecting the cognizance rate. Also, a Bayes action in each frame is supported by an evolution of prior distribution for the number of tags. From the simulation results, we observe that the pair of evolving prior distribution and Bayes action forms a robust scheme which attains a certain level of cognizance rate in spite of a high discrepancy between the Due and initially believed numbers of tags. Also, the proposed scheme is confirmed to be able to achieve higher cognizance completion probability than a scheme using classical estimate of the number of tags separately.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.13 no.4
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• pp.753-758
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• 2009

This paper is proposed the hardware structure and signal processing method of the RF-Tag based on heart sound to develop the mobile biomedical information device for the u-healthcare system. The RF-Tag in this study is consisted of a skin temperature sensor, a dynamic microphone for heart sound detection, Bluetooth communication to transmute healthcare data, and pulse period detection algorithm with adaptive gain controller. We experimented to evaluate performance of the RF-Tag in noisy environments. In addition, the RF-Tag has shown the good performance in the results of experiment. If the proposed methods in this study apply to design the u-healthcare device, we will be able to get the exact health data on real time in mobile environments.

• 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.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.27 no.11
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• pp.972-977
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• 2016

This paper introduces development process and results of HF & UHF band(13.56 MHz, 920 MHz) tag antennas using a single-side printing method on a PE film. The size of tag antenna is designed in the area of $80mm{\times}50mm$, little bit smaller than a credit card. The UHF tag antenna, $76mm{\times}44mm$, is located at the outside of the card size tag antenna, and the HF tag antenna, $40 mm{\times}42 mm$, is located at the center of the UHF tag antenna. The UHF and HF tag antennas are designed with consideration of coupling effects. The single-side printing method with a jumper structure without using a via is used to make a loop antenna of HF tag antenna. The reading range of UHF tag antenna is about 6m, and the reading of HF tag antenna is about 5 cm. The designed tag antennas have long enough reading ranges for both bands. The tag is applicable to logistics and authentification.

• The Journal of the Korea Contents Association
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• v.19 no.9
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• pp.637-645
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• 2019

The RFID group proof is an extension of the yoking proof proving that multiple tags are scanned by a reader simultaneously. Existing group proof schemes provide only delayed tag loss detection which detects loss of tag response in a verification phase. However, delayed tag loss detection is not suitable for real-time applications where tag loss must be detected immediately. In this study, I propose a tag response loss detection scheme which detects loss of tag response in the proof generation process quickly. In the proposed scheme, the tag responds with the sequence number assigned to the tag group, and the reader detects the loss of the tag response through the sequence number. Through an experiment for indistinguishability, I show that the sequence number is secure against an analyzing message attack to distinguish between specific tags and tag groups. In terms of efficiency, the proposed scheme requires fewer transmissions and database operations than existing techniques to determine which tags response is lost.

• Journal of Korea Multimedia Society
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• v.16 no.11
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• pp.1305-1314
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• 2013

The existing tag based system deducts a retrieval result with low accuracy through the usage of a single tag matching by using tags tagged in contents. And the system doesn't provide effectively contents related information which the tags have, as the users place tags on contents without considering the priority and associative relation between tags. For a solve of above problems, this paper suggests a tag ranking system which extracts semantic similarity between tags and re-ranks the tags tagged in contents. In order to evaluate the performance of suggested system, this paper experiments and compares the ranking result of this paper's tag ranking system with the result of baseline method using tags tagged in images and frequency method adapting tag co-appearance frequency.