• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2006.05a
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• pp.192-195
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• 2006

In this paper, we discuss the user-customized interaction for intelligent home environments. The interactive system is based upon the integrated techniques using speech recognition and fingerprint verification. For essential modules, the speech recognition and synthesis were basically used for a virtual interaction between the user and the proposed system. In experiments, particularly, the real-time speech recognizer based on the HM-Net(Hidden Markov Network) was incorporated into the integrated system. Besides, the fingerprint verification was adopted to customize home environments for a specific user. In evaluation, the results showed that the proposed system was easy to use for intelligent home environments, even though the performance of the speech recognizer was not better than the simulation results owing to the noisy environments

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2011.05a
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• pp.799-802
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• 2011

최근 RFID (Radio Frequency Identification) 기술은 다양한 분야에서 관심을 받고 사용되고 있으며 RFID와 모바일을 접목시켜 현대사회의 의사소통을 해결 하는데 많이 적용되고 있다. 학교에서는 학생과 교수간의 원활한 소통을 위하여 주기적인 상담이나 인터넷 상담과 같은 다양한 방법들을 사용하고 있다. 그러나 교수와 학생이 각자의 바쁜 일정에서 빈 시간을 내어 매번 약속을 해서 만난다는 것은 번거로운 일일 수 있다. 그러므로 교수와 학생간 좀 더 쉽게 소통 할 수 있도록 도와주는 시스템이 필요하다. 이를 위해 RFID와 안드로이드 기반 스마트폰을 이용하여 교수/학생 파워 메시징 시스템을 구축하였으며, 본 논문에서는 그 내용에 대해 기술한다. 이 시스템에서 학생은 RFID 태그가 부착된 학생증을 교수 방 앞에 설치된 RFID 리더기에 인식시키고, 그 순간 교수가 남긴 메시지를 확인할 수 있다. 또한 교수와의 상담시간을 예약 할 수 있으며, 본인의 메시지도 남길 수 있다. 교수는 자신의 일정을 관리 할 수 있고, 스마트폰을 통해 학생이 다녀간 방문 기록, 예약 정보, 학생이 남긴 메시지를 실시간 확인 할 수 있다. 이 시스템을 구축함으로써 교수와 학생의 소통 기회는 증가할 것이고, 또한 교수는 원격으로 학생과 지속적인 의사소통 기회를 가짐으로써 보다 효율적으로 학생을 관리할 수 있게 된다.

• IEIE Transactions on Smart Processing and Computing
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• v.6 no.4
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• pp.299-304
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• 2017

A wireless passive sensor network is a network consisting of sink nodes, sensor nodes, and radio frequency (RF) sources, where an RF source transfers energy to sensor nodes by radiating RF waves, and a sensor node transmits data by consuming the received energy. Against theoretical expectations, a wireless passive sensor network suffers from many practical difficulties: scarcity of energy, non-simultaneity of energy reception and data transmission, and inefficiency in allocating time resources. Perceiving such difficulties, we propose a simple contending-type medium access control (MAC) scheme for many sensor nodes to deliver packets to a sink node. Then, we derive an approximate expression for the network-wide throughput attained by the proposed MAC scheme. Also, we present an approximate expression for the optimal partition, which maximizes the saturated network-wide throughput. Numerical examples confirm that each of the approximate expressions yields a highly precise value for network-wide throughput and finds an exactly optimal partition.

• Proceedings of the CALSEC Conference
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• 2005.11a
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• pp.78-84
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• 2005

As the research activities related to 'Ubiquitous Computing' whose concept was introduced by Mark Weiser are growing, RFID(Radio Frequency Identification) technology has recently gained attention as a technology to advance the ubiquitous computing and a lot of related researches are also in progress. Research works done so far are mainly linked to the situation that the research outputs apply to meet the requirements for asset tracking and data sharing with partners over supply chain by using fixed RFID readers. However, it is essential that users have access to real-time information about the tagged objects and services whenever and wherever they want in the era of ubiquitous computing, so mobile devices-including PDA, smart phone, cellular phone, etc - which are equipped with an RFID reader can be regarded as an essential terminal for users living in ubiquitous computing environment. As far as the application with mobile devices are concerned, there are many considerations due to their limited capabilities of data processing, battery consumption and so on. In this paper, we review the generic RFID network model and introduce the revised RFID network model in consideration of incorporation with mobile devices equipped with an RFID reader. Also, we derive the requirements for software embedded within an RFID- enabled mobile terminal and then discuss essential components for implementation. Moreover, we develop the applications for asset management at museum by using mobile RFID network model.

• Journal of Korea Multimedia Society
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• v.17 no.12
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• pp.1461-1472
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• 2014

Recently, smart devices has been spreaded and the definition of RFID/USN(Radio Frequency Identification/Ubiquitous Sensor Network) technology has also extended. So, originally, human is an agent of communications but now, 'the things' are also an agent of communication. That is, Internet of Things(IoT). IoT is very big IT infra technology that is based on wire-wireless network technologies such as Bluetooth and Wi-Fi. However, in reality, IoT service that can provide various meaning and integrate smoothly is not appear yet. To solve these problems of IoT, we implemented Publish/Subscribe system, which operate in Zigbee based wireless sensor network by using MQTT-SN protocol. Moreover, this system can operate with combining MQTT system that is already existed in external Internet network so, extensibility and flexibility aspect is excellent. We show that possibility of IoT services that is combined between different heterogeneous network through the MQTT-SN.

• Journal of the Institute of Convergence Signal Processing
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• v.9 no.1
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• pp.46-53
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• 2008

This paper presents a 13.56 MHz RFID reader that can be used as a door-lock system for smart home security. The RFID reader consists of a transmitter, a receiver, and a data processing block. To verify the operation of the developed RFID reader, we present both a PSPICE simulation for transmitter/receiver and a digital simulation for data processing block. In particular, a CRC block for error detection of received data and a Manchester decoding block for position detection of collided data are designed using VHDL. In addition, we applied a binary search algorithm for multi-tag anti-collision. The anti-collision procedure is carried out by PIC microcontroller on software. The experimental results show that the developed reader can provide the right multi-tag recognition.

• ETRI Journal
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• v.38 no.6
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• pp.1052-1063
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• 2016

We propose a millimeter wave (MMW)-based mobile hotspot network (MHN) system for application in high-speed railways that is capable of supporting a peak backhaul link throughput of 1 Gbps per train at 400 km/h. The MHN system can be implemented in subways and high-speed trains to support passengers with smart devices and provide access to the Internet. The proposed system can overcome the inherent high path loss in MMW through system designs and high antenna gains. We present a simulation of the system performance that shows that a fixed beamforming strategy can provide high signal-to-interference-plus-noise-ratio similar to those of an adaptive beamforming strategy, with the exception of 15% of the train path in which the network can use link adaptation with low-order modulation formats or trigger a handover to maintain the connection. We also demonstrate the feasibility of the MHN system using a test bed deployed in Seoul subway line 8. The backhaul link throughput varies instantaneously between 200 Mbps and 500 Mbps depending on the SNR variations while the train is running. During the field trial, the smartphones used could make connections through offloading.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2016.05a
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• pp.579-580
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• 2016

In molds management systems using radio frequency identification (RFID), in the case where the RFID tag is lost, the RFID technology cannot be utilized to identify the location of the logistics. In order to solve this problem, a multi-sensor-based mold management system using RFID and infrared sensors is proposed in this paper. The proposed system uses RFID to identify the location of the mold and, by installing infrared sensors on the mold racks, the manager can identify the presence and location of the mold by reaffirming whether the mold exists in that location or not.

• JSTS:Journal of Semiconductor Technology and Science
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• v.10 no.1
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• pp.1-10
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• 2010

This paper proposes a two-phase clocked adiabatic static CMOS logic (2PASCL) circuit that utilizes the principles of adiabatic switching and energy recovery. The low-power 2PASCL circuit uses two complementary split-level sinusoidal power supply clocks whose height is equal to $V_{dd}$. It can be directly derived from static CMOS circuits. By removing the diode from the charging path, higher output amplitude is achieved and the power consumption of the diode is eliminated. 2PASCL has switching activity that is lower than dynamic logic. We also design and simulate NOT, NAND, NOR, and XOR logic gates on the basis of the 2PASCL topology. From the simulation results, we find that 2PASCL 4-inverter chain logic can save up to 79% of dissipated energy as compared to that with a static CMOS logic at transition frequencies of 1 to 100 MHz. The results indicate that 2PASCL technology can be advantageously applied to low power digital devices operated at low frequencies, such as radio-frequency identifications (RFIDs), smart cards, and sensors.

• International Journal of Contents
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• v.14 no.2
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• pp.1-6
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• 2018

In a wireless mobile communication system, a pilot signal has been considered to be a necessary signal for estimating a changing channel between a base station and a terminal. All mobile communication systems developed so far have a specification for transmitting pilot signals. However, although the pilot signal transmission is easy to estimate the channel,(Ed: unclear wording: it is easy to use the pilot signal transmission to estimate the channel?) it should be minimized because it uses radio resources for data transmission. In this paper, we propose a pilotless channel estimation scheme (PCE) by introducing the clustering method of unsupervised learning used in our deep learning into channel estimation.(Ed: highlight- unclear) The PCE estimates the channel using only the data symbols without using the pilot signal at all. Also, to apply PCE to a real system, we evaluated the performance of PCE based on the resource block (RB), which is a resource allocation unit used in LTE. According to the results of this study, the PCE always provides a better mean square error (MSE) performance than the least square estimator using pilots, although it does not use the pilot signal at all. The MSE performance of the PCE is affected by the number of data symbols used and the frequency selectivity of the channel. In this paper, we provide simulation results considering various effects(Ed: unclear, clarify).