• 한국정보통신설비학회:학술대회논문집
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• 2006.08a
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• pp.39-42
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• 2006

There are various analysis functions(including prediction of path loss, analyzing of capacity and coverage, etc.) of simulation tool to design and optimize the mobile communication network. Its reliability absolutely effects the performance of mobile communication network. Especially as the wireless network highly advancing focused on data service, it more needs to research and develop on the standard establishment of reliability of the simulation tool. Also it is important the systematic research how to improve the reliability of simulation tool. In this paper, to give the concrete process and skill about how to improve reliability, we define the kinds of reliability at first. And then we explain the comparison results between real field measurement data and theoretic simulation data.

• Journal of information and communication convergence engineering
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• v.20 no.3
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• pp.143-152
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• 2022

The ongoing adoption of 5G will increase the data traffic, throughput, multimedia services, and power consumption for future wireless applications and services, including sensor and mobile networks. Multipath fading on wireless channels also reduces the system performance and increases energy consumption. To address these issues, device-to-device (D2D) and cooperative communications have been proposed. In this study, we propose two inter-clustering models using the relay selection method to improve system performance and increase energy efficiency in cooperative D2D networks. We develop two inter-clustering models and present their respective algorithms. Subsequently, we run a computer simulation to evaluate each model's outage probability (OP) performance, throughput, and energy efficiency. The simulation results show that inter-clustering model II has the lowest OP, highest throughput, and highest energy efficiency compared with inter-clustering model I and the conventional inter-clustering-based multirelay method. These results demonstrate that inter-clustering model II is well-suited for use in 5G overlay D2D and cellular communications.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37C no.10
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• pp.915-924
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• 2012

Though a mobile device is equipped with a number of wireless communication interfaces in general such as Zigbee, Bluetooth, Wi-Fi, 3G, it uses only one interface for a specific service. In this paper, we propose a mechanism of adaptive switching between wireless communication interfaces in order to efficiently use various communication interfaces. Depending on the application service and the characteristics of wireless communication interface, mobile devices select an appropriate wireless communication interface and may switch to another interface during the service. As a result, power consumption can be reduced and the utilization of communication interface can be improved by using this mechanism.

• The Journal of the Korea Contents Association
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• v.13 no.5
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• pp.19-27
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• 2013

This paper implements the standby power control system composed of a master device and slave devices. The standby power is managed by cutting power supply after controlling the relay of a slave device based on the authentication of master device's RFID card. RFID interface and wireless communication module are embedded in a master device, and one master device is linked with many slave devices in wireless. Each slave device executes the operation needed in power control independently. We implements the function of manual power on/off system in a slave device, and the function of user ID enrollment by switch manipulation in a master device. Also this system can communicate bidirectionally in wireless and runs on TinyOS. The result of experiment shows that the user authentication is executed in a master device and this authenticated information is transmitted to a slave device in wireless, and standby power is cutted by controlling the relay of a slave device. Installing this system in a building or an office, we can expect energy saving.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.11a
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• pp.151-154
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• 2002

AP/RPCVD를 이용하여 $650^{\circ}C$의 저온에서 실리콘-게르마늄의 선택적 단결정 성장 (Selective Epitaxy Growth: SEG) 을 수행하였다. 본 실험에서는 $SiH_4$, $GeH_4$ 그리고 HCl 가스를 사용하여 잠입시간 동안 실리콘-게르마늄막을 성장시키고 연속해서 HCI 가스만을 주입하여 산화막 위에 형성되어진 작은 결정입자들을 식각하는 공정을 반복적으로 수행하였다. HCl 의 식각에 의해 한 주기의 잠입기 후에도 다시 잠입기가 존재함을 확인하였고, 이 성장법을 통하여 한 주기의 잠업시간 동안 증착할 수 있는 두께 이상으로 실리콘-게르마늄막의 선택적 성장이 가능하였다. 이는 저온 선택적 실리콘-게르마늄 성장 시 RPCVD에서 보이는 낮은 선택성과 $SiH_4$의 짧은 장입시간으로 인해 원하는 두께까지 확보하기 힘든 단점을 극복한 것이다. 선택성을 향상시키기 위해 실리콘-게르마늄 증착중 주입된 HCI의 유량에 따라 잠입시간과 증착속도에 영향을 주었으며, 연속공정을 위한 식각공정은 20sccm의 HCI을 20초간 주입하여 선택성을 유지하였다. 또한 보론 불순물의 첨가가 선택적으로 성장되는 박막의 결정성에 미치는 영향도 분석되었다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39C no.8
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• pp.696-707
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• 2014

In this paper, firstly, performance degradation due to the Private Distributed Reservation Protocol (DRP) conflict problem caused by devices' mobility is analyzed. And a novel relay transmission protocol combined with Private DRP conflict resolution is proposed to overcome the performance degradation at Private DRP conflicts. In order to give the loser device due to Private DRP conflicts another chance to maintain resources, the proposed relay transmission protocol executed at each device helps the loser device reserve another indirect link maintaining the required resources via a relay node.

• Journal of information and communication convergence engineering
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• v.8 no.4
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• pp.399-404
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• 2010

We propose a seamless IPTV transport technology of mobile device. This technology uses multiple interfaces of wireless communication on mobile device. This proposal for transportation of mobile IPTV contents is more mobile and adaptable than other wireless technologies that are currently being used. Algorithm of proposed technology is as follow. When the signal strength of the connected wireless network interface of mobile device is getting lower than specified level, another wireless network interface is connected to continue downloading the IPTV contents in advance. Another connection is maintained until the signal strength of the first connected interface is stable or the interface is connected to another base station (or AP) that have good signal strength. For more seamless services, we consider classifying the packets of mobile IPTV and using dynamic content quality select techniques. Dynamic content quality selection is based on notifying transfer rate to the content delivery network (CDN) server. The proposed technology is expected to use efficiently with both mobile IPTV and the transportation of mobile P2P/P4P.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.64 no.5
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• pp.739-745
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• 2015

In this paper, a flexible wireless power receiving system is proposed for wearable device applications. The proposed system is designed with printable component configuration to be integrable to textile material. While the defected ground structures(DGSs) are utilized for planar printable filter designs, direct impedance matching technique is considered for flexible circuit performance. The proposed system has been implemented on a flexible substrate with a thickness of 5 mils, and experimented for power conversion efficiencies and converted voltages. In order to evaluate the hardware flexibility, the system performance are measured a bended circuit board at a radius of curvature of 5 cm. The system performance is analyzed for the degradation due to the curvature. The proposed system has shown the excellent capability of far-field wireless power transfer systems in flexible device environments.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.12 no.10
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• pp.1830-1834
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• 2008

At the present day, devices for measurement and control of data by wireless based computer have been generalized. The devices with low cost and high performance have been spotlighted. If Zigbee communication solution is used in dangerous places and places that can not in use wire communication, computer can process data without limitation. Zigbee communication solution is effective in power consumption as compared with RF or bluetooth and can use battery. System cost of Zigbee also is very low, so can install lots of nodes. The system made in this paper transmit by wireless many LMCs(Laser Measuring Control) of wireless transmission system for distance measurement and many slave Zigbee to a master Zigbee.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.6 no.2
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• pp.566-579
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• 2012

Ubiquitous computing called pervasive one is based on the thought of pervading ability of computation in daily life applications. In other words, it aims to include computation in devices such as electronic equipment and automobiles. This has led to disengagement of computers from desktop form. Accordingly, the notice in ubiquitous computing being taken of a world steeped in remote and wireless computer-based-services. Handheld and wearable programmed devices such as sense and control appliances are such devices. This advancement is rapidly moving domestic tasks and life from device-and-human communication to the device-and-device model. This model called Machine to Machine (M2M) has led to acceleration of developments in sciences such as nano-science, bio-science, and information science. As a result, M2M led to appearance of applications in various fields such as, environment monitoring, agricultural, health care, logistics, and business. Since it is envisaged that M2M communications will play a big role in the future in all wireless applications and will be emerged as a progressive linkage for next-generation communications, this paper aims to consider how much M2M architectures can realize ubiquitous computing in daily life applications. This is carried out after acquainting and initiating readers with M2M architectures and arguments for M2M. Some of the applications was not achievable before but are becoming viable owing to emergence of M2M communications.