• Information and Communications Magazine
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• v.25 no.10
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• pp.7-17
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• 2008

RFID 시스템은 유통물류 분야를 비롯해 다양한 분야에서 활용되고 있지만, RFID 시스템에서의 태그 및 리더 충돌로 인해 태그의 인식효율 및 인식속도의 감소가 RFID시스템의 확산에 걸림돌이 되고 있다. 본고에서는 RFID 시스템의 효율을 높이기 위한 태그 및 리더 충돌방지 알고리즘들을 소개한다. 특히, ISO 18000-6 Type C 수동형 RFID 시스템에서의 태그 및 리더 충돌방지 알고리즘에 대하여 집중적으로 알아본다.

• Korean Architects
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• no.6 s.147
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• pp.35-37
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• 1981

• Korean Architects
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• no.3 s.156
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• pp.15-19
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• 1982

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.12A
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• pp.925-932
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• 2009

Precise temperature monitoring is the major preconditioning to supervise quality losses within the transport chain for fresh products. ISO/IEC18000-6REV1 defines new protocols supporting BAP(Battery Assisted Passive) RFID tag which is completely compatible with EPCglobal Class1 Generation2 specification. In this paper, we designed a modem supporting BAP RFID tag with FPGA(Field Programmable Gate Array) and implemented sensor data processing function defined in ISO/IEC18000-6REV1. The transmit block of the modem supports pulse shaping filter and the output signal of the implemented RFID reader is satisfied with the spectrum mask defined in the standard. The receive block of the modem uses Gardner TED to synchronize timing of symbol. In this paper, we designed a modem supporting ISO/IEC18000-6REV1 standard and developed a RFID reader sndard. The developed RFID reader sndard can recognize sensor tag and passive tag in the wireless environment and supports real-time processing of the sensor data in the embedded linux platform.

• Journal of the Institute of Electronics and Information Engineers
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• v.53 no.6
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• pp.29-36
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• 2016

A wireless passive sensor network is a network which, by letting separate RF sources supply energy to sensor nodes, is able to live an eternal life without batteries. Against expectations about an eternal life, however, a wireless passive sensor network still has many problems; scarcity of energy, non-simultaneity of energy reception and data transmission and inefficiency in resource allocation. In this paper, we focus on a wireless passive sensor network providing a packet service which is tolerable to packet losses but requires timely delivery of packets. Perceiving the practical constraints, we then consider a contending-type MAC scheme, rooted in framed and slotted ALOHA, for supporting many sensor nodes to deliver packets to a sink node. Next, we investigate the network-wide throughput achieved by the MAC scheme when the packets transmitted by geographically scattered sensor nodes experience path losses hence capture phenomena. Especially, we derive an exact formula of network-wide throughput in a closed form when 2 sensor nodes reside in the network. By controlling design parameters, we finally optimize the contending-type MAC scheme as to attain the maximum network-wide throughput.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.41 no.10
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• pp.915-921
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• 2017

Recently, studies to reduce vibration and noise of automobiles have been actively conducted. However, previous studies did not concentrate on the optimization of the mount system with passive or active mounts. This study analytically studies an active mounting system with three active structural paths between source and receiver and the feasibility has been verified. Active mounting system has a coupled structure of piezoelectric stack actuators and passive mounts. A dynamic model of the whole system is prepared and the control force and phase of the stack actuators in each path are determined to target full isolation of each path. Its performance on vibration attenuation is investigated and based on it, optimized combinations of passive and active paths for the best attenuation are presented.

• Journal of KIISE:Computer Systems and Theory
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• v.33 no.12
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• pp.907-917
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• 2006

In this paper, we propose a strategy to improve fault-tolerance and scalability of replicated services in mobile agent systems by applying an appropriate passive replication protocol for each replicated service according to whether the service is deterministic or non-deterministic. For this purpose, two passive replication protocols, PRPNS and PRPDS, are designed for non-deterministic and deterministic services respectively. They both allow visiting mobile agents to be forwarded to and execute their tasks on any node performing a service agent, not necessarily the primary agent. Especially, in the protocol PRPDS, after a backup service agent has received each mobile agent request and obtained its delivery sequence number from the primary service agent, the backup is responsible for processing the request and coordinating with the other replica service agents. Therefore, our strategy using the two proposed protocols can promise high scalability of replicated services a large number of mobile agents attempt to access in mobile agent systems. Our simulation results show that the proposed strategy performs much better than the one using only the traditional passive replication protocol.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37 no.2C
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• pp.181-187
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• 2012

Millimeter wave (MMW) readily penetrates fabrics, thus it can be used to detect objects concealed under clothing. A passive MMW imaging system can operate as a stand-off type sensor that scans people in both indoors and outdoors. However, because of the diffraction limit and low signal level, the imaging system often suffers from low image quality. Therefore, suitable statistical analysis and computational processing would be required for automatic analysis of the images. In this paper, a real-time concealed object detection is addressed by means of the multi-level segmentation. The histogram of the image is modeled with a Gaussian mixture distribution, and hidden object areas are segmented by a multi-level scheme involving $k$-means, the expectation-maximization algorithm, and a decision rule. The complete algorithm has been implemented in C++ environments on a standard computer for a real-time process. Experimental and simulation results confirm that the implemented system can achieve the real-time detection of concealed objects.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.20 no.4
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• pp.117-134
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• 2010

A passive RFID tag which received attention as a future technology for automatic and quick identification faces some difficulties about security problems such as tag authentication, reader authentication, data protection, and untraceability in addition to cost and reliable identification. A representative passive RFID technology is the ISO/IEC 18000-6 Type C which is an international standard for 900 MHz UHF-band. This standard has some difficulties in applying to the security services such as originality verification, tag's internal information protection, and untraceability, because it does not provide high-level security solution. In this paper, we summarize security requirements of ISO/IEC ITC 1/SC 31 international standardization group, propose security protocols suitable for the UHF-band passive RFID system using a crypto engine, and analyze its security strength. In addition, we verify that it is possible to implement a tag conforming with the proposed security protocols by presenting concrete command/response pairs and cryptographic method.

• The Journal of Society for e-Business Studies
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• v.16 no.3
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• pp.113-127
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• 2011

An RFID system has been widely applied in many areas over the initial SCM application. In the literature enormous RFID applications in healthcare are documented to improve patient safety, patient/provider logistics, and the efficiency of collecting data. Based on the proposed 4-layered RFID system architecture, we introduce a case that implemented an UHF passive RFID-based tracking system in an outpatient clinic. Particularly, we propose a method to process RFID data that contains noise and missing reads. The proposed method for processing unreliable RFID data is capable to locate the tag accurately and provide additional business information. We finally conclude the paper with identifying obstacles and what is necessary to ensure system reliability.