• Journal of the Institute of Electronics Engineers of Korea SD
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• v.44 no.1
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• pp.16-21
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• 2007

A Dual-Path Voltage Multiplier for passive RFID Tags was proposed and fabricated by using a 0.25um CMOS process with additional steps for schottky diodes. The proposed circuit needs only 4 additional diodes, and the area increment compared to conventional one is negligible in multi-stage voltage multipliers. The simulation and measurement results show that the output power capability of proposed multiplier are about two times larger than the conventional half-wave multiplier.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.15 no.10
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• pp.2247-2256
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• 2011

In this paper, we propose a coordinator-based reader protocol that can avoid reader collisions in a passive RFID system. In a proposed protocol, unlike conventional protocols that a reader itself selects its own slot randomly to communicate with tags such as DCS, Colorwave, a coordinator reader allocates an unused slot to a reader to participate in the network and sends a current slot number. A reader allocated a slot can communicate with tags. The proposed protocol can adaptively modified to apply for multiple coordinator readers environment in a wide area. This causes reader collision problem, but can be alleviated partly by applying the frequency planning. In this way, we verifies that a RFID system using the proposed protocol is three to five times better than existing systems through the simulation.

• Journal of the Korea Society for Simulation
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• v.17 no.4
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• pp.99-112
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• 2008

In the passive UHF (860-960MHz) RFID communications, which consists of a set of readers and tags, the readers normally interrogate the tag by using the backscatter mechanism. (i.e., tag response). In practical RFID environment, where multiple readers or tags exist; the interference causes collisions. This paper proposes a centralized arbitration scheme for avoiding the collision problems among multiple readers. The proposed centralized arbitration scheme is modeled in software environments, and is verified with simulation results. Simulated performance is focused on completion time, utilization and response time, and the simulation results show that our proposed scheme provides satisfactory performance grade.

• The KIPS Transactions:PartC
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• v.16C no.2
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• pp.267-274
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• 2009

For the implementation of a RFID system, an anti-collision algorithm is required to identify multiple tags within the range of a RFID Reader. There are two methods of anti-collision algorithms for the identification of multiple tags, conclusive algorithms based on tree and stochastic algorithms based on slotted ALOHA. In this paper, we propose a Dynamic Framed Slotted ALOHA-Slot Congestion(DFSA-SC) Algorithm. The proposed algorithm improves the efficiency of collision resolution. The performance of the proposed DFSA-SC algorithm is showed by simulation. The identification time of the proposed algorithm is shorter than that of the existing DFSA algorithm. Furthermore, when the bit duplication of the tagID is higher, the proposed algorithm is more efficient than Query Tree algorithm.

• Proceedings of the KSR Conference
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• 2008.11b
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• pp.1264-1269
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• 2008

We designed a track circuit of Tag in-tag out type that can be used for light rails and monorails. This method is called RFID-Tag and it literally uses RFID-Tag and replaces a fixed track circuit and implements a moving block. The distance between RFID-Tags is set to the length of a train and thus a train is always in contact with one of the tags. A train runs in RFID-Tag in -RFID-Tag out type at all times and the distance between trains can be precisely controlled through the application of a moving block combined with the basic principle of a fixed block, which enables the continuous speed control and enhances the satisfaction of passengers. When constructing a track circuit using RFID-Tag the Tag in-tag out brings us the cost reduction and is more economical than the existing fixed track circuit in that sense and easy for installation and maintenance. The wireless communication between onboard and wayside makes the continuous control possible and can improve the control capacity of ATP/ATO by the implementation of a moving block on top of a fixed one.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.16 no.6
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• pp.25-35
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• 2006

Radio Frequency identification (RFID) will become an important technology in remotely object identification systems. However, the use of RFID tags may create new threats to the sniな and Privacy of individuals holding RFID tags. These threats bring several problems which are information leakage of a tag, location trace of individuals and impersonation of a tag. Low-cost RFID systems have much restrictions such as the limited computing power, passive power mechanism and low storage space. Therefore, the cost of tag's computation should be considered as an important factor in low-cost RFID systems. We propose an authentication protocol, OHLCAP which requires only one one-way hash function operation and hence is very efficient. Furthermore, our protocol is suitable to distribution database environment. Hence our scheme can be applied to ubiquitous computing environment.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.24 no.10
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• pp.1319-1324
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• 2020

A smart tag complements various problems caused by the expansion of the use of existing magnet cards. This emerged as a result of the need for alternative means to perform safer and more diverse functions. RFID tags are becoming increasingly ubiquitous sensor networks and Internet of Things technologies as they give everything an ID, enabling automatic recognition of objects and forming a communication network between them. In this paper, a contactless RFID smart tag reader composed of RFID tags and readers using AVR processor was developed. The system has a low frequency band of 13.56MHz and is designed by PWM method of communication velocity 26.48kbps. The developed RFID smart tag board showed a faster response rate than the typical RFID system as a result of the simulation, and the actual experiment also showed an improvement in response rate.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.5
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• pp.931-936
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• 2016

The PS algorithm divides the number of tags within the identification range of reader into smaller groups by increasing the transmission power incrementally and identifies them. It limits the number of responding tags by grouping the tags within the identification range of the reader, and thus can reduce the probability of tag collision. Also, in the PS algorithm, the reader takes advantages of the difference of identification ranges. This algorithm uses the fixed frame size at every scan. Therefore, it has problems that the performance can be shown variously according to the number of tags and frame size. In this paper, we propose an EPS algorithm that allocates the optimal frame size by estimating the number of tags at each scan, and apply it into the STAC protocol. The simulation results showed that STAC/EPS algorithm can improve the identification delay about 45% compared with STAC protocol. Also, it provides a stable identification delay regardless of power level increase.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.11A
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• pp.1130-1137
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• 2006

One of the important performance issues in large-scale RFID systems is to resolve collisions among responses from RFID tags. Considering two do facto anti-collision solutions, namely the binary-tree splitting algorithm and the Slotted-Aloha algorithm, we propose to use multi-packet reception (MPR) capability to enhance the RFID tag reading rate (i.e., throughput). MPR allows an RFID reader to receive multiple reponses transmitted by tags at the same time. We analyze the effect of MPR capability in the above anti-collision algorithms, which is also validated by simulation. The analysis and simulation results show that RFID reader antenna design and signal separation techniques play an important role in improving RFID system performance with MPR capability.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.4C
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• pp.197-206
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• 2011

In the RFID system, bulk tag information is stored into the back-end database as plaintext format not ciphertext. In this case, the tags's private informations can be easily compromised by an external hacker or an insider attacker. If the private informations of tags disclosed by the attackers, it can occur serious privacy invasion problem. Recently the database(DB) security is an important issue to prevent the above DB compromised attack. However, DB security for RFID systeme has not been considered yet. If we use the DB security technique into the RFID system, the above described privacy invasion' problem can be easily prevented. Based on this motivation, this paper proposes a secure and efficient back-end database security and authentication(S-DB) scheme with XOR-based encryption/decryption algorithm. In the proposed scheme, all tag's private information is encrypted and stored by using the DB secret key to protect the DB compromised attack. As a result, the proposed S-DB scheme 'can provide stronger security and more efficiency for the secure RFID system environment.