• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2006.05a
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• pp.970-973
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• 2006

In this paper, this system implements a wireless parking lots management using RFID. Universal RFID Reader uses the software and specifies the class of UHF band. And then, it can recognize UHF band tags controlling the hardware. It can provide more efficient administration of physical distribution.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.7 no.7
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• pp.1624-1637
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• 2013

In RFID systems, one important issue is how to effectively address tag collision, which occurs when multiple tags reply simultaneously to a reader, so that all the tags are correctly identified. However, most existing anti-collision protocols assume isotropic collisions where a reader cannot detect any of the tags from the collided signals. In practice, this assumption turns out to be too pessimistic since the capture effect may take place, in which the reader considers the strongest signal as a successful transmission and the others as interference. In this case, the reader disregards the other collided tags, and in turn, fails to read the tag(s) with weaker signal(s). In this paper, we propose a capture effect-aware anti-collision protocol, called Multi-Round Collision Tree (MRCT) protocol, which efficiently identifies the tags in real RFID environments. MRCT deals with the capture effect as well as channel error by employing a multi-round based identification algorithm. We also analyze the performance of MRCT in terms of the number of slots required for identifying all tags. The simulation results show that MRCT significantly outperforms the existing protocol especially in a practical environment where the capture effect occurs.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.2B
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• pp.279-286
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• 2010

RFID reader protocol is an interface between RFID readers and higher (host) such as RFID middlewares and applications. At present, reader protocols provided by vendors are different from each other and there are compatibility problems in environment using heterogeneous readers. In this paper, to solve this problem, an RFID reader which supports LLRP(Low Level Reader Protocol), a well-known standard reader protocol presented by EPCglobal is designed and implemented. It is designed with two modules and supports various interfaces for easy adaptation to various applications. The LLRP protocol is implemented over a embedded LINUX multi-thread environment. It not only supports almost all properties of LLRP, and is designed with flexible hardware/software architecture to meet various requirements.

• Journal of the Korean Operations Research and Management Science Society
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• v.37 no.4
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• pp.95-109
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• 2012

Being able to quickly locate valuable medical equipment is critical inside hospitals. In order to utilize limited budget and resources efficiently, accurate locating or tracking is required in many fields. In this research, we focus on how to find the location of missing assets by using RFID in real time indoors to track equipment. When equipment needs to be searched, the purpose of a RFID device is to minimize the time, investment cost and effort spent searching for the equipment. Thus, this research presents a mathematical model of using RFID (both handheld reader and stationary reader) for efficient asset location. We derive the expected time of locating RFID-tagged objects in a multi-area environment where hand-held RF readers are used. We then discuss where to deploy stationary RF readers in order to maximize the efficiency of the search process.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.1
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• pp.358-362
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• 2013

RFID reader platform with self-diagnosis function studied in this paper has an automatic state recognition function, a report function, and an automatic upgrade function. Also, since it uses frequency operation policy in multiple reader environments, it will be frequently used in the large operation environment and multi-readers environment. Therefore, the technology can meet the demands not only in the domestic RFID market, but in the global market.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.6 no.3
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• pp.101-110
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• 2007

This study has designed a circular polarization antenna for UHF bandwidth RFID reader. As a result of performance test of the antenna designed it is found that return loss (S11) is about -45.529dB at 914MHz, which is relatively small, and antenna gain is about 6.09dBi. It has also been confirmed that $50{\Omega}$ impedance matching is about $50.48{$\Omega}$ and it can be applied to every RFID reader. Therefore, the antenna is designed to have higher gain of circular polarization by improving reception, which is one of the most important parameters of RFID reader and is expected to be extensively used to recognize multi-tag in the distance.

• Korean Journal of Radiology
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• v.25 no.4
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• pp.351-362
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• 2024

Objective: To measure inter-reader agreement and identify associated factors in interpreting complete response (CR) on magnetic resonance imaging (MRI) following chemoradiotherapy (CRT) for rectal cancer. Materials and Methods: This retrospective study involved 10 readers from seven hospitals with experience of 80-10210 cases, and 149 patients who underwent surgery after CRT for rectal cancer. Using MRI-based tumor regression grading (mrTRG) and methods employed in daily practice, the readers independently assessed mrTRG, CR on T2-weighted images (T2WI) denoted as mrCR_T2W, and CR on all images including diffusion-weighted images (DWI) denoted as mrCR_overall. The readers described their interpretation patterns and how they utilized DWI. Inter-reader agreement was measured using multi-rater kappa, and associated factors were analyzed using multivariable regression. Correlation between sensitivity and specificity of each reader was analyzed using Spearman coefficient. Results: The mrCR_T2W and mrCR_overall rates varied widely among the readers, ranging 18.8%-40.3% and 18.1%-34.9%, respectively. Nine readers used DWI as a supplement sequence, which modified interpretations on T2WI in 2.7% of cases (36/1341 [149 patients × 9 readers]) and mostly (33/36) changed mrCR_T2W to non-mrCR_overall. The kappa values for mrTRG, mrCR_T2W, and mrCR_overall were 0.56 (95% confidence interval: 0.49, 0.62), 0.55 (0.52, 0.57), and 0.54 (0.51, 0.57), respectively. No use of rectal gel, larger initial tumor size, and higher initial cT stage exhibited significant association with a higher interreader agreement for assessing mrCR_overall (P ≤ 0.042). Strong negative correlations were observed between the sensitivity and specificity of individual readers (coefficient, -0.718 to -0.963; P ≤ 0.019). Conclusion: Inter-reader agreement was moderate for assessing CR on post-CRT MRI. Readers' varying standards on MRI interpretation (i.e., threshold effect), along with the use of rectal gel, initial tumor size, and initial cT stage, were significant factors associated with inter-reader agreement.

• Journal of the Korea Safety Management & Science
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• v.10 no.2
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• pp.155-162
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• 2008

The ubiquitous, which is developed for human's convenience, uses the concept of situation awareness that communicates with computer and performs a certain work without user's recognition. In order to collect the information of situation, many devices are required. Also, in the condition of ubiquitous middleware, priority is given to effective controls of various devices. There are many devices for collecting the information of situation awareness such as sensor, RFID, etc. Among them, in the use of RFID, the researcher performed the experiment, in which multiple readers were used depending on the necessity of awareness information, and found the problem of intervention between readers occurring when multiple readers are used. The paper handles the problem of intervention causing from using multiple readers and suggests middleware design module using session manager to solve the problem.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.12
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• pp.1719-1724
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• 2013

In this paper, a size-reduction technique is presented for the RFID reader antenna working at two UHF bands. To tackle the problem of size increase in multi-band applications, two resonance paths are made to occur in one geometry with a single feed. While one resonance path is combined with the other, the entire geometry is determined to guarantee the resonance at the target frequencies through the dual-band input impedance matching. The antenna performance is predicted by the full-wave simulation, and the design method is verified by observing the good agreement between the simulated and measured results. At the two frequencies, the satisfactory return loss as well as the antenna efficiency and peak gain of the far-field pattern is obtained.

• Journal of KIISE:Information Networking
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• v.36 no.2
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• pp.118-129
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• 2009

The ISO 18000-7 Active RFID standard, a single channel system operating in the 433Mhz, faces technical difficulties in supporting some recently introduced application demands because of its low transmission rates and radio interference between readers. We propose a new multi-channel active RFID system operating in the 2.4Ghz. The special feature of the proposed system is that a reader makes use of multiple interfaces to improve its performance like a multi-core processor. However if only a small part of interfaces are actually used, the performance improvement would not meet the expectation. To overcome this problem, a new multi-channel multi-interface active RFID protocol, which balances communication loads among all available interfaces, is necessary. 3 protocols, named as "Aggregated", "LP-Combined", "AP-Balanced", are proposed. Through simulation, we compare them for various conditions by changing number of tags, number of interfaces, tag data size. AP-Balanced shows the best performance and its performance increases almost linearly as the number of interface increases, which meets our expectation.