• ETRI Journal
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• v.30 no.3
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• pp.486-488
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• 2008

In this paper, a scheme to increase the throughput of RFID systems is presented, which considers the capture effect in the context of framed ALOHA protocol. Under the capture model in which the probability of one tag is identified successfully depending on the number of tags involved in the collision, two probabilistic methods for estimating the unknown number of tags are proposed. The first method is the maximum likelihood estimation method, and the second method is an approximate algorithm for reducing the computational time. The optimal frame size condition to maximize the system throughput by considering the capture effect is also presented.

• Journal of information and communication convergence engineering
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• v.6 no.4
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• pp.391-395
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• 2008

Wideband terminal and base station is required to serve not only existing 1st and 2nd generation mobile communication systems but also 3rd generation systems. In this paper, we present a feasibility study on coaxial feed compact wideband antenna for UHF RFID reader application. The original antenna was designed for partial discharge detection sensor in high voltage diagnostic system. However, we modified the original prototype to achieve shifted down resonant frequency for wideband wireless communication applications. The experimental result shows good return loss characteristics and radiation patterns except for the total gain at each resonant frequency. The maximum measured gain was 2.45 dBi$\sim$3.18 dBi at 910MHz.

• Journal of information and communication convergence engineering
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• v.5 no.4
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• pp.311-315
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• 2007

This paper proposes a revised query tree algorithm in RFID systems. The proposed QT_ecfi algorithm revises the QT algorithm, which has a memory-less property. In the QT_ecfi algorithm, the tag will send the remaining bits of their identification codes when the query string matches the first bits of their identification codes. When the reader receives all the responses of the tags, it knows which bit is collided. If the collision occurs in the last bit, the reader can identify two tags simultaneously without further query. While the tags are sending their identification codes, if the reader detects a collision bit, it will send a signal to the tags to stop sending. According to the simulation results, the QT_ecfi algorithm outperforms the QT algorithm in terms of the number of queries and the number of response bits.

• Journal of Institute of Control, Robotics and Systems
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• v.13 no.9
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• pp.915-919
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• 2007

This paper proposed a transponder detection method to reduce recognition time in RFID system. It's also shown that conventional procedure of communication in the system could cause a waste of time when a reader recognizes a transponder. The reduction of recognition time can be obtained by developing a circuit to detect a transponder actively. Detecting a transponder is achieved by using the voltage variation of reader antenna voltage that happens when a transponder approaches to the vicinity of magnetic field formed by the reader. By adding a comparator to the antenna receiver of a reader, the reader can perceive approach or existence of a transponder. A reader for experiment is made using the MFRC500 by Phillips that supports ISO/IEC 14443 protocol. Comparing the proposed method with the conventional methods by experiment, there are 47.5ms reduction of recognition time maximally and 12ms in average.

• Journal of information and communication convergence engineering
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• v.7 no.3
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• pp.292-296
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• 2009

The performance of anti-collision algorithm in RFID systems, which are based on FSA algorithm, may be affected by the frame size a query round. In this paper, an anti-collision algorithm with early cancellation of query round is proposed to enhance the performance of EPCglobal Class-1 Gen-2. The Q-algorithm calculates a Q value to determine the next frame size during a query round. In the proposed algorithm, if the new Q value is different from the previous one, the reader transmits a QueryAdjust command to cancel the current query round. The simulation results show that the proposed algorithm can have a stable performance irrespective of the C value of Q-algorithm and the number of tags.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.8 no.11
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• pp.3997-4015
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• 2014

Radio frequency identification (RFID) is an emerging wireless communication technology which allows objects to be identified automatically. The tag anti-collision is a significant issue for fast identifying tags due to the shared wireless channel between tags and the reader during communication. The EPCglobal Class-1 Generation-2 which uses Q algorithm for the anti-collision is widely used in many applications such as consumer electronic device and supply chain. However, the increasing application of EPCglobal Class-1 Generation-2 which requires the dynamic environment makes the efficiency decrease critically. Furthermore, its frame length (size) determination and frame termination lead to the suboptimal efficiency. A new anti-collision algorithm is proposed to deal with the two problems for large-scale RFID systems. The algorithm has higher performance than the Q algorithm in the dynamic environment. Some simulations are given to illustrate the performance.

• Proceedings of the Korea Society for Industrial Systems Conference
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• 2006.05a
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• pp.407-410
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• 2006

최근 들어 반도체의 기술적인 성장과 네트워크의 발전으로 유비쿼터스 컴퓨팅 환경이 대두되고 있으며 이에 따라 RFID라는 신기술이 등장과 응용에 관한 연구가 활발히 진행되고 있다. 이에 본 논문에서는 기존 RFID 시스템에서 유선망을 사용한 데이터 전송으로 인하여 발생될 수 있는 공간 및 이동성의 제약을 극복하기위하여 저가의 무선전송모듈을 적용하여 휴대형 상품정보제공 시스템을 개발하였다. 무선전송 모듈은 900MHz 대역의 Texas Instruments 사의 TRF6901 chipset을 이용하였고, 이를 제어하는 MPU는 TI사의 MSP430F149로 설계하였다. 본 논문에서 개발한 시스템은 도서관리, 출입통제 시스템등에 범용적으로 적용될 수 있을 뿐 아니라 핸드 헬드형 RFID 시스템에 혁신적인 기대 효과를 예상할 수 있다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.10 no.8
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• pp.1428-1434
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• 2006

In this paper, we propose the scheme solving privacy infringement in RFID systems with improving the scalability of back-end server. With RFID/USN becoming important subject, many approaches have been proposed and applied. However, limits of RFID, low computation power and storage, make the protection of privacy difficult. The Hash Chain scheme has been known as one guaranteeing forward security, confidentiality and indistinguishability. In spite of that, it is a problem that requires much of computation to identify tags in Back-End server. In this paper, we introduce an efficient key search method, the Hellman Method, to reduce computing complexity in Back-End server. Hellman Method algorism progresses pre-computation and (re)search. In this paper, after applying Hellman Method to Hash chain theory, We compared Preservation and key reference to analyze and apply to parallel With guaranteeing requistes of security for existing privacy protecting Comparing key reference reduced computation time of server to reduce computation complex from O(m) to $O(\frac{m{^2/3}}{w})$ than the existing form.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.15 no.9
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• pp.1971-1978
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• 2011

In RFID-based cold-storage systems, product locations are recognized as the logical locations of RFID readers which are attached to the entrance of the cold rooms. However, through these methods, product locations can be incorrect in many different situations of a storage. Cold storage rooms have a huge rage in temperature, and the product in the cold-storage spoils easily. Therefore, highly precise product locations is very important for the product quality In this paper, a new approach is suggested to manage the storage location inaccuracy by adding two readers to existing forklift and attaching RFID tags to the ceiling. One reader recognizes ceiling tags to acquire location data, and the other recognizes product tags to acquire product detail data loaded on the forklift. The product can be seamlessly tracked and traced in realtime by monitoring and analyzing data gathered from these readers. Through the proposed location management method, the effectiveness of the product management in cold-storage can be improved consequently.

• The Journal of the Korea Contents Association
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• v.11 no.6
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• pp.33-41
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• 2011

RFID technology is already used in the various application fields such as identification card, traffic card and etc. Many RFID application systems using UHF have been developed in the field of asset management, logistics and security. Because a human being can make mistakes, we need the system that can efficiently manage the special assets such as small arms, jewelry and medicine and can monitor them in real time. In this paper, we proposed a special assets management system to keep assets in safe custody, to monitor their safety status in real time and to manage distribution channels and history of those assets. The developed system is called Smart Cabinet because it has cabinet's form. Smart Cabinet integrates such technologies as RFID, smart card, fingerprint recognition, several sensors and LCD display in order to provide the functions for special asset management. Those functions include condition monitoring of assets, traceability management, distribution channels and security logs, which are to interact with a management server. The article demonstrated the potentiality of RFID by presenting special asset management solutions dedicated to guns and medicine management, and also showed the effectiveness and possibility of those solutions.