• Journal of electromagnetic engineering and science
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• v.4 no.4
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• pp.183-189
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• 2004

In this paper, the Eigen-RAKE receiver in wideband direct sequence code-division multiple access(DS-CDMA) systems with downlink smart antenna is analyzed for different spreading bandwidths(1.25 MHz, 5 MHz, 10 MHz) and different channel environments(macro, micro). The realistic spatio-temporal wideband multipath channel is assumed, one of which is standardized multiple-input single-output(MISO) radio channel model for WCDMA link-level simulations proposed by $3^{rd}$ generation partnership project(3GPP) contributions. We assumed spatial scattering phenomenon in which many unresolvable path signals within a limited range of spatial angle simultaneously contribute to the signals received at the receiver. Several multipaths within one chip are distinguished into each one and the first multipath components are selected as the desired signal and the others are considered self-interference. Downlink DS-CDMA system with eigenbeamformer using wider bandwidth present better performance than that using narrow bandwidth system by employing Eigen-RAKE receiver of many number of branches. It is shown that the downlink eigenbeamformer is more effective in typical urban macro cellular environments when using Eigen-RAKE receiver.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.6
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• pp.1261-1267
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• 2011

Electricity meters using in Korea are about 1.8 million units. From among these, electronic meters for high voltage, about 170 thousand units were installed to the digital type meter and ones for low voltage installed hundreds of thou-sands of meters through a model project. Recently, low voltage meter are expected to complete the installation within several years. Domestic power metering technology is being beyond a simple framework with an electronic type and is rapidly evolving to intelligent smart metering systems in conjunction with promotion of a national smart grid project. Accordingly, it is important to ensure an immunity of meter for electromagnetic field and environmental noise at the installation site. In this paper, we are going to check the validity of international standard that focusing on RF electromagnetic field immunity of meter to secure the quality and improve the reliability in field operation of meter. And we will verify the validity of test specification focused on actual installation environment and are going to offer the improvement plan of test standard.

• Journal of the Korea Society of Computer and Information
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• v.15 no.11
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• pp.173-183
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• 2010

The purpose of this study is to examine the factors influencing RFID(Radio Frequency IDentification) diffusion. This study has been reviewed various theoretical research relating to innovation diffusion theory and RFID. The model was tested Structural Equation Modeling(SEM) using Smart PLS 2.0 analysis on the sample collected from 73 companies. The result of hypothesis testing is as follows. First, standardization, IS infrastructure influence positively RFID integration. Second, perceived benefits, inter-organizational cooperation, competitive pressure influence positively RFID usage. Third, RFID integration influence positively RFID usage. The results of this study will provide various implications on RFID diffusion.

• Journal of Korean Society of Water and Wastewater
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• v.31 no.2
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• pp.141-148
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• 2017

The waterworks company is in charge of managing water facilities buried underground, and the management has been centered on manholes. However, since there is no standard management manual, it has been impossible to introduce and operate a systemized managing tool by water service providers and managers, and manhole management has been carried out by individual data recording personnel for each water service provider. When the management is carried out individually, the data to be shared by other waterworks managers tend to be privatized, and consequently, it may become a big obstacle to proceed with many civil works such as emergency leak repair, road excavation, replacement of old buildings. This report introduces RFID (Radio Frequency Identification) system which is based on the magnetic field capable of IOT. It also describes the necessity of leveraging the system for smart managing of pipe management record that has been done by hand writing. The RFID system includes RFID marker, data reader, portable computer operating program, and data base server operating program. In this system, the data is managed with a single communication device, and it would be possible to share the information on the underground facilities and water treatment facilities. This RFID technology is expected to provide water service providers with opportunities to develop more scientific and modernized underground facilities information systems.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.29 no.4
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• pp.285-289
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• 2018

In this paper, we demonstrate electromagnetic wave focusing and rectification based on time reversal as a smart method for far-field wireless power transfer. Time reversal in a complex propagation environment allows for transmission of high peak power pulses by focusing the electromagnetic waves selectively regardless of the receiver position. We demonstrate wave focusing and radio frequency (RF) to direct current (DC) rectification via numerical simulation of a complex propagation environment. The results reveal that time reversal can ensure peak power up to 12 dB greater compared to a narrowband continuous wave signal, thereby enhancing the rectified DC voltage with better efficiency.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.6 no.2
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• pp.480-497
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• 2012

As a new business concept, machine-to-machine (M2M) communications are born from original telemetry technology with the intrinsic features of automatic data transmissions and measurement from remote sources typically by cable or radio. M2M includes a number of technologies that need to be combined in a compatible manner to enable its deployment over a broad market of consumer electronics. In order to provide better understanding for this emerging concept, the correlations among M2M, wireless sensor networks, cyber-physical systems (CPS), and internet of things are first analyzed in this paper. Then, the basic M2M architecture is introduced and the key elements of the architecture are presented. Furthermore, the progress of global M2M standardization is reviewed, and some representative applications (i.e., smart home, smart grid and health care) are given to show that the M2M technologies are gradually utilized to benefit people's life. Finally, a novel M2M system integrating intelligent road with unmanned vehicle is proposed in the form of CPS, and an example of cyber-transportation systems for improving road safety and efficiency are introduced.

• Proceedings of the KSR Conference
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• 2008.06a
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• pp.535-544
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• 2008

Unlike MS(Magnetic Stripe), SMART CARD is equipped with COS(Chip Operating System) consisting of the Microprocessor and Memory where information can be stored and processed, and there are two types of cards according to the contact mode; the contact type that passes through a gold plated area and the contactless one that goes through the radio-frequency using an antenna embedded in the plastic card. the contactless IC card used for the transportation card was first introduced into local area buses in Seoul, and expanded throughout the country so that it has removed the inconvenience such as possession of cash, fare payment and collection. Focusing on the Seoul metropolitan area in 2004, prepaid and pay later cards were adopted and have been used interchangeably between a bus and subway. The card terminal compatible between a bus and subway is Proximity Integrated Circuit Card(PICC) as international standards(1443 Type A,B), communicates in the 13.56MHz dynamic frequency modulation-demodulation system, and adopts the Multi Secure Application Module(SAM). In the second half of 2009, the system avaliable nationwide will be built when the payment SAM standard is implemented.

• Journal of the Korea Society of Computer and Information
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• v.12 no.5
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• pp.155-162
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• 2007

For providing smart home service, middleware technologies for electronic appliance control by network and user location information for location based service are important. Recently research using ultrasonic and radio signal are affected by the obstacle. In this paper, we suggest inertial sensor that is not affected by the obstacle. Also, we use RFID for initializing position. It solve error accumulation and position initialize problem. In this paper, we suggest following system for smarthome service and localization. This system are composed smarthome middleware, user localization system on middleware, inertial sensor and RFID Reader. This system shows operation without affect of obstacle in smarthome environment.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2010.10a
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• pp.438-440
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• 2010

As market expansion and demand for smart phone have increased, the wireless data trafic is rapidly growing now. To solve this problem, common carriers in Korea distribute the trafic over Wi-Fi. Smart phones have multi interfaces such as 3G radio, Wi-Fi, Bluetooth, and etc and can utilize them. However these interfaces support seamless handover between not different interfaces but same interfaces, so that users couldn't be supported continuity for handover. In this paper, we describe the Media Independent Handover(MIH) services that is proposed by IEEE 802.21. The standard enhance the handovers across heterogeneous access networks and to optimize the service continuity during handovers.

• Healthcare Informatics Research
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• v.24 no.4
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• pp.387-393
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• 2018

Objectives: This paper describes an experience of implementing seamless service trials online and offline by adopting Internet of Things (IoT) technology based on near-field communication (NFC) tags and Bluetooth low-energy (BLE) beacons. The services were provided for both patients and health professionals. Methods: The pilot services were implemented to enhance healthcare service quality, improve patient safety, and provide an effective business process to health professionals in a tertiary hospital in Seoul, Korea. The services to enhance healthcare service quality include healing tours, cancer information/education, psychological assessments, indoor navigation, and exercise volume checking. The services to improve patient safety are monitoring of high-risk inpatients and delivery of real-time health information in emergency situations. In addition, the services to provide an effective business process to health professionals include surveys and web services for patient management. Results: Considering the sustainability of the pilot services, we decided to pause navigation and patient monitoring services until the interference problem could be completely resolved because beacon signal interference significantly influences the quality of services. On the other hand, we had to continue to provide new wearable beacons to high-risk patients because of hygiene issues, so the cost increased over time and was much higher than expected. Conclusions: To make the smart connected hospital services sustainable, technical feasibility (e.g., beacon signal interference), economic feasibility (e.g., continuous provision of new necklace beacons), and organizational commitment and support (e.g., renewal of new alternative medical devices and infrastructure) are required.