• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.1
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• pp.565-568
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• 2005

RFID system allows contactless identification of objects, where small tags are attached to objects and information of objects are transferred using radio frequency. In recent years, industries have incorporated several identification systems to its production processes, which allow collecting automatically information about goods. In order to communicate with a single tag out of a group of tags, the target tag has to be identified. Therefore the read has to attempt to obtain the unique identification code of each tag within its read range. This paper presents performance results of QT and QT-sl protocols, which are tag identification protocols incorporating memoryless property. The memoryless property is that the current response of each tag only depends on the current query of the reader but not on the past history of the reader's queries.

• The Journal of the Korea Contents Association
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• v.7 no.4
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• pp.10-19
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• 2007

In this paper, Class-1 Air-interface protocols of EPCglobal applied to RFID system in UHF band are analyzed, and the standard anticollision algorithms are realized. Also, the improved anticollision algorithms of the Class-1 Generation-1 and Generation-2 protocol are proposed and the performances of anticollision algorithms are compared. As the results, reduction ratio of total tag recognition time of the improved Generation-1 algorithm is 54.5% for 100 tags and 63.4% for 1000 tags with respect to standard algorithm, respectively. And the reduction ratio of the improved Generation-2 algorithm is 7.9% for 100 tags and 11.7% for 1000 tags. Total recognition times of the improved algorithms are shorter than those of standard algorithms according to increasing the number of tag. Therefore, the improved anticollision algorithm proposed in this paper is the advanced method improving the performance of tag recognition in the RFID system.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.10
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• pp.41-49
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• 2013

This paper suggests the dielectric resonator antenna using LTCC process for mm-wave car radar system. In this paper, dielectric resonator antennas (DRA) operated in 76-77 GHz frequency band are designed. And, using the LTCC process, the structures of dielectric resonator with SRR (split ring resonator) inside and those of dielectric resonator with probe inside are suggested. Linear polarization antennas and circular polarization antenna are designed for the DRA with probe inside. Three kinds of the DRA antennas are designed and their characteristics are calculated using CST RF simulation tool. The designed antennas are fabricated and measured and the measured results are compared with calculated results. The measured operating frequencies of DRAs are within 76 GHz to 77 GHz, which are close to the calculated results, and the measured gains are about 8.15 dBi to 10.82 dBi.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.3
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• pp.470-475
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• 2012

In Q-algorithm of EPCglobal Class-1 Gen-2 RFID system, the initial value of $Q_{fp}$, which is the slot-count parameter, is not defined in the standard. And the values of weight C, which is the parameter for incrementing or decrementing the slot-count size, are not determined. Therefore, if the number of tags is small and we let the initial $Q_{fp}$ be large, the number of empty slot will be large. On the other hand, if we let the initial $Q_{fp}$ be small in spite of many tags, almost all the slots will be collided. Also, if the reader selects an inappropriate weight, there are a lot of empty or collided slots. As a result, the performance will be declined because the frame size does not converge to the optimal point quickly during the query round. In this paper, we propose a scheme to allocate the optimal initial $Q_{fp}$ through the tag number estimation and select the weight based on the slot-count size of current query round.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.6B
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• pp.585-594
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• 2009

Efficient filtering is an important factor in RFID system performance. Because of huge volume of tag data in future ubiquitous environment, if RFID readers transmit tag data without filtering to upper-layer applications, which results in a significant system performance degradation. In this paper, we provide an efficient filtering technique which operates on RFID air protocol. RFID air protocol filtering between tags and a reader has some advantages over filtering in readers and middleware, because air protocol filtering reduces the volume of filtering work before readers and middleware start filtering. Exploiting the air protocol filtering advantage, we introduce a geometrical algorithm for generating air protocol filters and verify their performance through simulation with analytical time models. Results of dense RFID reader environment show that air protocol filtering algorithms reduce almost a half of the total filtering time when compared to the results of linear search.

• The Korean Journal of Physiology
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• v.25 no.2
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• pp.211-221
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• 1991

Although the existence of nerve cells which determine the activity of sympathetic nervous system in ventrolateral medulla is advocated recently, there are wide varieties on the location and function of them according to authors. Present study aimed to identify and characterize the medullospinal tract cells in rostral and caudal medulla of cats .which branch to the lateral horn of the upper thoracic spinal cord. Cats were anesthetized with ${\alpha}-chloralose$. The upper thoracic spinal cord and floor of the IVth ventricle were exposed. Medullospinal tract cells in rostral and caudal medulla were identified by anti-dromic stimulation of the intermediolateral nucleus in the upper thoracic cord and then the location and physiological characteristics of these cells were studied. A total of seventy cells in medulla had constant latency and responded to high frequency stimulation to thoracic cord. Among them fifty-six cells were identified as medullospinal tract cells either by collision with spontaneous activities or activities evoked by sciatic nerve stimulation(27/56), or by determining the refractory period (29/56). Thirty-one of these cells branched to the contralateral thoracic spinal cord, twenty-one cells to the ipsilateral side and remaining four cells branched to both sides. The conduction velocity of cells branching to the contralateral side was $29{\pm}2.9\;m/sec$ and that of cells to the ipsilateral side was $39.1{\pm}6.0\;m/sec$. When medulla was devided into two by a horizontal plane at 3 mm rostral to the obex, fifty-one among seventy cells were in the rostral medulla and nineteen were in the caudal medulla. The conduction velocities of these two groups were $21.6{\pm}1.0\;and\;33.3{\pm}3.9\;m/sec$, respectively. In this study, we confirmed the existence of two groups of medullospinal tract cells in rostral and caudal ventrolateral medulla, which branch to the lateral horn of thoracic cord and these cells have relatively few spontaneous activities and rapid conduction velocity, so we concluded that these cells are different from the previously known sympatho-related cells in ventrolateral medulla.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.5C
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• pp.415-421
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• 2005

Passive RFID tag does not have its own power, so it has very poor computation abilities and it can deliver signals in very short range. From the facts, most RFID Tag security schemes assumed that the backward channel from tags to a reader is safe from eavesdropping. However, eavesdroppers near a tag can overhear message from a tag illegally. In this paper, we propose a method to protect the backward channel from eavesdropping by illegal readers. The proposed scheme can overcome the problems of conventional schemes such as randomized tree walking, which have been proposed to secure tag information in tree-walking algorithm as an anti-collision scheme for RFID tags. We showed the efficiency of our proposed method by using an analytical model, and it is also shown that the proposed method can provide the probability of eavesdropping in some standardized RFID tag system such as EPCglobal, ISO, uCode near to '0'.