• Proceedings of the Korean Association of Geographic Inforamtion Studies Conference
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• 2008.10a
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• pp.297-302
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• 2008

The positioning technology for a moving object is an important and essential component of ubiquitous computing environment and applications, for which Radio Frequency Identification(RFID) has been considered as a core technology. RFID-based positioning system calculates the position of moving object based on k-nearest neighbor(k-nn) algorithm using detected k-tags which have known coordinates and kcan be determined according to the detection range of RFID system. In this paper, RFID-based positioning system determines the position of moving object not using weight factor which depends on received signal strength but assuming that tags within the detection range always operate and have same weight value. Because the latter system is much more economical than the former one. The geometries of tags were determined with considerations in huge buildings like office buildings, shopping malls and warehouses, so they were determined as the line in I-Dimensional space, the square in 2-Dimensional space. In 1-Dimensional space, the optimal detection range is determined as 125% of the tag spacing distance through the analytical and numerical approach. Here, the analytical approach means a mathematical proof and the numerical approach means a simulation using matlab. But the analytical approach is very difficult in 2-Dimensional space, so through the numerical approach, the optimal detection range is determined as 134% of the tag spacing distance in 2-Dimensional space. This result can be used as a fundamental study for designing RFID-based positioning system.

• Proceedings of the Korean Association of Geographic Inforamtion Studies Conference
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• 2008.10a
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• pp.270-271
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• 2008

The positioning technology for a moving object is an important and essential component of ubiquitous communication computing environment and applications, for which Radio Frequency IDentification Identification(RFID) is has been considered as also a core technology for ubiquitous wireless communication. RFID-based positioning system calculates the position of moving object based on k-nearest neighbor(k-nn) algorithm using detected k-tags which have known coordinates and k can be determined according to the detection range of RFID system. In this paper, RFID-based positioning system determines the position of moving object not using weight factor which depends on received signal strength but assuming that tags within the detection range always operate and have same weight value. Because the latter system is much more economical than the former one. The geometries of tags were determined with considerations in huge buildings like office buildings, shopping malls and warehouses, so they were determined as the line in 1-Dimensional space, the square in 2-Dimensional space and the cubic in 3-Dimensional space. In 1-Dimensional space, the optimal detection range is determined as 125% of the tag spacing distance through the analytical and numerical approach. Here, the analytical approach means a mathematical proof and the numerical approach means a simulation using matlab. But the analytical approach is very difficult in 2- and 3-Dimensional space, so through the numerical approach, the optimal detection range is determined as 134% of the tag spacing distance in 2-Dimensional space and 143% of the tag spacing distance in 3-Dimensional space. This result can be used as a fundamental study for designing RFID-based positioning system.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.4
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• pp.731-736
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• 2017

In this paper, we propose a simplified tag collection algorithm to improve the performances of ISO/IEC 18000-7, which is a standard for an active RFID system. The proposed algorithm modifies the collection command that enables to start a tag collection round. The modified collection command includes the results of the listen period response for the previous collection round. Tags that receive the collection command check the collision status for their responses. If there is no collision, tags transmit their additional data and go into the sleep mode without the point-to-point read command and sleep command. A collection round for the standard consists of a collection command and response, a read command and response, and sleep command. On the other hand, in the proposed algorithm, a collection round consists of a collection command and response. The simulation results showed that the proposed algorithm can improve the identification delay about 16% compared with the standard when the number of tags are 300.

• Journal of the Korea Society of Computer and Information
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• v.16 no.4
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• pp.149-157
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• 2011

Passive tags are inferior to active tags in processing efficiency, so they have difficulty in largevolume processing. The proposed protocol reduces the volume of computation in passive tags and, at the same time, improves authentication for enhanced safety and security. That is, different from existing RFID protocols that return the same value even if an error happens when the reader reads a tag, the improved RFID security protocol returns a new value using a re-counter and processes the computation part of a tag in the reader or in a back.end system. Even if the information of a tag is acquired by an malicious way, it is not actual information but encrypted information that is not usable. In addition, even if tag information is read in sequence, it is changed in each read, so the protocol is safe from Location Tracking.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.41 no.8
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• pp.55-62
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• 2004

This paper proposes and analyzes two anti-collision algorithms in Ubiquitous ID system. We mathematically compares the performance of the proposed algorithms with that of binary search algorithm slotted binary tree algorithm using time slot, and bit-by-bit binary tree algorithm proposed by Auto-ID center. We also validated analytic results using OPNET simulation. Based on analytic result comparing the proposed Modified bit-by-bit binary tree algorithm with bit-by-bit binary tree algorithm which is the best of existing algorithms, the performance of Modified bit-by-bit binary tree algorithm is about 5% higher when the number of tags is 20, and 100% higher when the number of tags is 200. Furthermore, the performance of proposed Enhanced bit-by-bit binary tree algorithm is about 335％ and 145% higher than Modified bit-by-bit binary tree algorithm for 20 and 200 tags respectively.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.45 no.6
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• pp.204-212
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• 2008

Active RFID tags are currently used in harbor transportation; they are attached to cargo containers for sea transportation. They are designed to be able to be identified by RFID readers installed at ports in many countries. The international standard ISO/IEC 18047-7 regarding RFID conformance test methods suggests the use of air interface evaluation between an RFID reader and a tag. However, the test method suggested by the international standard is intended to detect a radio signal over only a very short period. Outcomes were uncertain, making it difficult to evaluate the system accurately. This paper proposes a new evaluation method by incorporating a 'self-running test mode' environment into the RFID tags in order to reduce the test time and increase testing accuracy. We found that the application of the suggested method to actual tags improves measurement time and uncertainty over that obtained using existing methods.

• Fashion & Textile Research Journal
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• v.16 no.5
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• pp.800-810
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• 2014

In this study, the current status of product information of functional outdoor jackets in the hang-tags was investigated in perspective of consumer protection. Effectiveness and preferred alternatives to hang-tag information were also investigated. For the market survey, 1560 hang-tags from 676 functional outdoor jackets were investigated. For the effectiveness and preferred alternatives, 472 adults in their 20-60's were surveyed. The average number of hang-tags was 2.3 but 5.9% did not provide any product information. The contents included functional property of fabric; quality guarantee; brand introduction; product characteristics; instructions for care/usage; subsidiary material information, and they were different depending on end-use of jackets. Consumers strongly wanted explanations of the terms used in the hang-tag and could not accurately figure out the functions of the products from hang-tag information regardless of expression methods. The percentage of incorrect answer of 'figure/foreign language' method was extremely high. It is a noticeable feature of graph method that customers perceived that the graph was difficult to understand, but the percentage of correct answers was much higher than other methods, implying that graph method was possibly more useful at delivering accurate information to the customers who pursuit information. Customers strongly agreed to need of alternative methods and preferred an unified performance grade from selected functions based on the end-use of products. Customers also wanted to include the information of performance change after laundering. The results could provide practical insights to the consumers, companies, and the government to prepare proper guideline/policies for consumer protection.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.1B
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• pp.17-26
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• 2005

RFID(Radio Frequency IDentification) is a technology that automatically identifies objects attached with electronic tags by using radio wave. For the implementation of an RFID system, an anti-collision algorithm is required to identify several tags within the RFID reader's range. Few researches report the performance trade-off among anti-collision algorithms in terms of the communications traffic between the reader and tags, the identification speed, and so on. In this paper, we analyze both tree based memoryless algorithms and slot aloha based algorithms that comprise of almost every class of existing anti-collision algorithms. To compare the performance, we evaluated each class of anti-collision algorithms with respect to low-cost RFID system with 96-bit EPC(Electronic Product Code). The results show that the collision tracking tree algorithm outperforms current tree based and aloha based algorithms by at least 2 times to 50 times.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.3
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• pp.747-754
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• 2013

This paper proposed a new transponder detection method to reduce tag recognition time and simplify anti-collision process in RFID systems. In conventional systems, a transponder in detectable area is passively recognized by responding to a reader command. In addition, if there are multiple tags in the area, a collision between tags occurs by responding at the same time to a command and anti-collision process begins. In the proposed method, tags are actively recognized without any command from a reader which results to reducing a tag recognition time and simplifying anti-collision process. To compare transponder recognition time, the process of transponder recognition in conventional systems is analysed. A circuit to detect transponder directly is developed and antenna voltage variation of a reader in the appearance of multiple transponders is analysed for the implementation of the proposed method.

• Journal of KIISE:Computing Practices and Letters
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• v.14 no.4
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• pp.401-411
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• 2008

Folksonomy, which is created through the collaborative tagging from many users, is one of the driving factors of Web 2.0. Tags are said to be the web metadata describing a web document. If we are able to find the semantic subsumption relationships between tags created through the collaborative tagging, it can help users understand the metadata more intuitively. In this paper, targeting del.icio.us tag data, we propose a method named FolksoViz for deriving subsumption relationships between tags by using Wikipedia texts. For this purpose, we propose a statistical model for deriving subsumption relationships based on the frequency of each tag on the Wikipedia texts, and TSD(Tag Sense Disambiguation) method for mapping each tag to a corresponding Wikipedia text. The derived subsumption pairs are visualized effectively on the screen. The experiment shows that our proposed algorithm managed to find the correct subsumption pairs with high accuracy.