• Journal of IKEEE
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• v.24 no.4
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• pp.1093-1097
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• 2020

This work describes the design and characterization of a Ku-band monolithic microwave integrated circuit (MMIC) power amplifier (PA) for satellite communication applications. The device technology used relies on 0.25 ㎛ gate length gallium arsenide (GaAs) pseudomorphic high electron mobility transistor (PHEMT) of wireless information networking (WIN) semiconductor foundry. The developed Ku-band PHEMT MMIC power amplifier has a small-signal gain of 22.2~23.1 dB and saturated output power of 34.8~35.4 dBm over the entire band of 13.75 to 14.5 GHz. Maximum saturated output power is a 35.4 dBm (3.47 W) at 13.75 GHz. Its power added efficiency (PAE) is 30.6~37.83% and the chip dimensions are 4.4 mm×1.9 mm. The developed 3 W PHEMT MMIC power amplifier is expected to be applied in a variety of Ku-band satellite communication applications.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2002.04a
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• pp.614-618
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• 2002

In hot strip mills, Portable Roll Scanner (the portable roll surface temperature and profile measuring device) can be used to calibrate on-line Process models for strip crown and flatness by measuring the thermal expansion and wear profile of the rolls. And the surface temperature measurement can be used to optimize the roll cooling system. Portable Roll Scanner consists of the measuring device, which has two contact inductive distance transducers for roll profile measurement and one infrared Pyrometer for surface temperature measurement, and computer-based controller that is equipped with the measuring device. By the wireless data communication, the data is transferred to the memory of notebook for further analysis. After roll extraction from mills, Portable Roll Scanner measure the roll profile and surface temperature simultaneously along the work roll face and display the results in the TFT color monitor of notebook. Portable Roll Scanner is useful at mill-side and roll grinding shop.

• Electronics and Telecommunications Trends
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• v.32 no.6
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• pp.27-39
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• 2017

A variety of medical devices are utilized to repair or help injured body functions after accidental injury(such as a traffic accident), population aging, or disease. Such medical devices are being actively researched and developed in portable form, skin patchable type, and further, implantable form. In the future, active implantable medical devices for neuro and brain sciences are expected to be developed. Active implantable medical devices that detect brain signals and control neurology for a wider understanding of human cognition and nerve functions, and for an understanding and treatment of various diseases, are being actively pursued for future use. In this paper, the core elements of implantable devices that can be applied to neuro and brain sciences are classified into electrode technologies for bio-signal acquisition and stimulation, analog/digital circuit technologies for signal processing, human body communication technologies, wireless power transmission technologies for continuous device use, and device integration technologies to integrate them. In each chapter, the latest technology development trends for each detailed technology field are reviewed.

• Proceedings of the KIEE Conference
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• 2007.10c
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• pp.172-174
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• 2007

An electronic watt-hour meter with high-precision measurement technology can provide many valuable metering data of a real-time system measurements, such as per-phase voltage, ampere, active power, reactive power, apparent power, power factor, and system frequency. Also many of accumulated metering data such as active energy, reactive energy, apparent energy, and load profile can be gettable from an electronic watt-hour meter[1]. This paper presents an approach of the small-sized AMR (Automatic Meter Reading) that provides customers with a very valuable electrical service. This AMR service transmits lots of a valuable metering data by using ZigBee communication module, so that users resided in their premises can use the information to audit a power quality and improve their electrical conditions by using the PQ monitoring device equipped with ZigBee receiver. This PQ monitoring device shows metering data on LCD and transmits to the PC through an internal network. Also, the device can keep the valuable meter data into a built-in non-volatile memory. The final goal of this paper is to better understand the power quality of electrical systems and offer the power qualify information for the convenience of all power consumers.

• Proceedings of the KIEE Conference
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• 2003.04a
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• pp.402-404
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• 2003

Radio frequency identification (RF-ID) is an automatic data capture (ADC) technology that comprises small data-carrying device(is called Tag) and fixed or mobile device(is called reader). Tags are attached or deattached device. Readers may be installed at locations where data capture is required, and may also be in the form of portable readers. In this paper, we are proposing an application for the subway station using the RF-ID system and a system for the gateless fare collection passing through the booth in only carrying the card. In this system that RF-ID system and Bluetooth are applied. We designed two wireless communication channels. One is the 125kHz communication channel by FSK and PSK for power supplying on the card and identification and the other is 2.4GHz channel for the collection.

• International Journal of Internet, Broadcasting and Communication
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• v.10 no.2
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• pp.7-12
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• 2018

The spread of IoT (Internet of Things) technology that connects objects based on wired / wireless networks is accelerating, and IoT-based smart home technology that constitutes a super connected network connecting sensors and home appliances existing inside and outside the home is getting popular. In addition, demand for alternative energy technologies such as photovoltaic power generation is rapidly increasing due to rapid increase of consumption of energy resources. Recently, small solar power systems for general households as well as large solar power systems for installation in large buildings are being introduced, but they are effectively implemented due to limitations of small solar panels and lack of power management technology. In this paper, we have studied smart home structure and IoT / IoL device discovery algorithm for energy harvesting system based on photovoltaic power generation, It is possible to construct an efficient smart home system for device control.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.6 no.1
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• pp.131-146
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• 2012

As one of the four basic technologies of IOT (Internet of Things), M2M technology whose advance could influence on the technology of Internet of Things has a rapid development. Mobile Payment is one of the most widespread applications in M2M. Due to applying wireless network in Mobile Payment, the security issues based on wireless network have to be solved. The technologies applied in solutions generally include two sorts, encryption mechanism and authentication mechanism, the focus in this paper is the authentication mechanism of Mobile Payment. In this paper, we consider that there are four vital things in the authentication mechanism of Mobile Payment: two-way authentication, re-authentication, roaming authentication and inside authentication. Two-way authentication is to make the mobile device and the center system trust each other, and two-way authentication is the foundation of the other three. Re-authentication is to re-establish the active communication after the mobile subscriber changes his point of attachment to the network. Inside authentication is to prevent the attacker from obtaining the privacy via attacking the mobile device if the attacker captures the mobile device. Roaming authentication is to prove the mobile subscriber's legitimate identity to the foreign agency when he roams into a foreign place, and roaming authentication can be regarded as the integration of the above three. After making a simulation of our proposed authentication mechanism and analyzing the existed schemes, we summarize that the authentication mechanism based on the mentioned above in this paper and the encryption mechanism establish the integrate security framework of Mobile Payment together. This makes the parties of Mobile Payment apply the services which Mobile Payment provides credibly.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.8 no.6
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• pp.89-95
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• 2008

The introduction of wireless information technology gives rise to new mobile services in all kinds of areas of out daily life. Mobile healthcare system is a production of composite ICT (Information and Communication Technology) which focused on signal sensing, processing, and communication in wireless environment. The mobile and wireless revolution promises not only expanded access to patient health information, but also improved patient care. In this paper, we describe a surrogate host based mobile healthcare information system which utilized Grid computing for real-time ECG signal processing. The surrogate host provides seamless interface between mobile device and Medical Grid portal. The security extension of GSI (Grid Security Infrastructure) allows mobile users to access Grid portal in a secure and convenient manner. The presented system architecture can be used as a secure enterprise mobile healthcare system for hospital physicians.

• KIPS Transactions on Computer and Communication Systems
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• v.3 no.4
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• pp.107-114
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• 2014

Things in the IoT(Internet of Things) make various services by exchanging information over networks. The IoT includes many types of WSNs(Wireless Sensor Networks) that consists of spatially distributed wireless sensor nodes and operates with the various purposes with useful technologies such as identification, sensing and communication. Typically, Zigbee network composed of low-cost and lowpower devices is mainly used for wide-area monitoring and remote device control systems. The IoT composed of various WSNs cannot interoperate among networks because of heterogeneous communication protocol and different data representation of each network, but can facilitate interconnection and information exchange among networks via the DDS, which is communication middleware standard that aims to enable real-time, high performance and interoperable data exchanges. In this paper, we proposed design of Zigbee Adaptor for two-way interoperation and data exchange between Zigbee network and other networks in the IoT. Zigbee Adaptor communicates with Zigbee network according to the Zigbee protocol and communicates with external networks via DDS. DDS-based Zigbee Adaptor can facilitate interoperation between a Zigbee network and external networks by systematic cooperation among its components.

• Journal of the Korean Magnetics Society
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• v.24 no.6
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• pp.179-185
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• 2014

The existing USB connection type of the clip-type pulsmeter equipped with a Hall sensor and a permanent magnet does not have any error or malfunction to measure the pulse wave. The property of the wireless networking system communicating the pulse wave data through the wireless LAN communication by combination USB with Ethernet and Ethernet to Wi-Fi converting system instead of existing USB connection method was investigated. There are exited that the patient needs to stay at close site of the desktop PC without USB connector and the wireless transfer and receiver networking system has pulse wave measurement SW to receive the pulse wave data. Thus it is expected that the study becomes helpful to measure and transfer the exact pulse wave of the patient in a comfortable pose at close range.