• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.7
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• pp.3351-3369
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• 2017

In recent years, datacenters, network devices and computers have proliferated. The power consumed by information and communication technology (ICT) devices has inflated in an extraordinary manner. Green communication has emerged as a new approach to reduce and optimize power consumption in ICT sector. Many methods and protocols have been proposed and implemented to achieve green communication. Nevertheless, the increase of power consumption remains a problem. In this work, we attempt to reduce and optimize power consumption of network devices in datacenters environment utilizing software defined network (SDN) paradigm. To gain more insight of the power consumption requirements of network switches, a power measurement system is constructed to measure power consumption levels of network devices. Subsequently, we propose a duplication resolver algorithm (DRA) to power off/on switches reactively. DRA algorithm reduces the required time by switches to construct their flow tables after rebooting. To this end, DRA-based external circuit has been constructed utilizing Ethernet module and an Arduino kit to control power supplies of network devices. To facilitate our work, a testbed has been constructed utilizing Ryu SDN controller, HP2920-24G switches and Arduino kits. Our results show that DRA algorithm can reduce both the power usage and start-up time delay of network switches after failures.

• Journal of Advanced Marine Engineering and Technology
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• v.39 no.1
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• pp.52-57
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• 2015

In this paper, we studies on the RF characteristics of the transmission line employing IPACD (inverted periodically arrayed capacitive devices) on MMIC (monolithic microwave integrated circuit) for application to wireless communication system. According to measured results, the novel transmission line employing IPACD showed a wavelength much shorter than conventional transmission lines. In addition, the IPACD structure showed an effective permittivity much higher than conventional ones. We also extracted the bandwidth characteristic of the IPACD structure using equivalent circuit analysis. According to the results, the cut-off frequency of the proposed structure was 129.2 GHz.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.6
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• pp.1106-1112
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• 2017

As the Internet of Things (IOT) is evolving into an industry-wide service and expanded to the concept of Internet of Everything (IoE), services using IoT devices are easily accessible in everyday life. IoT requires more devices to collect information and is expected to increase the number of devices by 50 billion by 2020, and is about the number of devices currently available. Gradually, the number of mobile devices, smart devices, and Internet devices is increasing, and energy resources are required to operate such a large number of Internet devices, and the energy consumed by each device is small. In this paper, we consider the number of devices to be increased and generate a signal irrespective of transmission information so that power other than the energy required for signal transmission is consumed. When transmission information is generated and near to a receiver to receive information, The method to be used as an analysis is designed through experiments.

• Proceedings of the IEEK Conference
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• 2000.11b
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• pp.25-28
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• 2000

In this paper, three types of organic electroluminescent devices(OELD) were fabricated on mechanically flexible plastic substrate by using vacuum deposition method. The devices consist of a hole transporting material such as TPD, a light-emitting material such as Alq$\sub$3/ and an electron transporting material, blocking material such as PBD. Electrical and optical properties of these OELDs were measured. This paper shows that organic small molecules based on OELD can be successfully deposited on a flexible plastic substrate. This points open the potential for low cost mass production of flexib]e displays, including roll to roll processing.

• Proceedings of the Korea Contents Association Conference
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• 2019.05a
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• pp.7-8
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• 2019

This paper presents a hybrid blockchain-based Identity Management Framework for devices in Microgrid. It incorporates the use of a Public and Private Blockchain platform to store and authenticate Microgrid device identities. It also emphasizes the shared responsibility of the manufacturers to provide the first layer of authentication for the devices they produce. Identities of each device are stored in the private and public Blockchain and authenticated using physically unclonable functions (PUF) and cryptographic functions.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.12 no.4
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• pp.1396-1414
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• 2018

With the proliferation of the Internet of Things (IoT) healthcare devices, significant interoperability issue arises where devices use proprietary data transfer protocols. The IHE PCD-01 standard has been suggested for the exchange of healthcare data in ISO/IEEE 11073 PHD data model. However, the PCD-01 is not efficient to be used in the IoT environment. This is because the use of SOAP for PCD-01 may be too complex to be implemented in the resource-constrained IoT healthcare devices. In this paper, we have designed a communication system to implement ISO/IEEE 11073 and IHE PCD-01 integration using the IETF CoAP. More specifically, we have designed the architecture and procedures, using CoAP, to seamlessly transmit the bio-signal from the tiny resource-constrained IoT healthcare devices to the server in a standardized way. We have also built the agent, gateway, and PCD-01 interface at the server, all of which are using the CoAP as a communication protocol. In order to evaluate the performance of the proposed system, we have used the PCD data to be transmitted over CoAP, MQTT, and HTTP. The evaluation of the system performance shows that the use of CoAP results in faster transaction and lesser cost than other protocols, with less battery power consumption.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2005.11a
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• pp.391-396
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• 2005

In this dissertation, we discuss the trends of policy and analyze the technical regulation for the extremely low power devices in other countries. In addition, this paper proposes a draft revision of technical regulation for new efficient electric field strength of extremely low power devices in accordance with the technical requirement of Electromagnetic Compatibility. Based on these researches, the contents of this study will be useful to contribute a domestic efficient expansion and development of extremely low power devices and strengthen a competitiveness on international communication markets.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.48 no.6
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• pp.47-55
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• 2011

The performance of data transmission from mobile devices to cloud storages is limited by the amount of data being transferred, communication speed and battery consumption of mobile devices. Especially, when the large-scale data communication takes place using mobile devices, such as smart phones, the performance turbulence and power consumption become an obstacle to establish the reliable communication environment. In this paper, we present an efficient data transmission method using USB Hijacking. In our approach, the synchronization to transfer a large amount of data between mobile devices and user PC is executed by using USB Hijacking. Also, there is no need to concern about data capacity and battery consumption in the data communication. We presented several experimental results to verify the effectiveness and suitability of our approach.

• Journal of Electrical Engineering and Technology
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• v.12 no.3
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• pp.1307-1313
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• 2017

Sensor networks are composed of provide low powered, inexpensive distributed devices which can be deployed over enormous physical spaces. Coordination between sensor devices is required to achieve a common communication. In low cost, low power and short-range wireless environment, sensor networks cope with significant resource constraints. Security is one of main issues in wireless sensor networks because of potential adversaries. Several security protocols and models have been implemented for communication on computing devices but deployment these models and protocols into the sensor networks is not easy because of the resource constraints mentioned. Memory intensive encryption algorithms as well as high volume of packet transmission cannot be applied to sensor devices due to its low computational speed and memory. Deployment of sensor networks without security mechanism makes sensor nodes vulnerable to potential attacks. Therefore, attackers compromise the network to accept malicious sensor nodes as legitimate nodes. This paper provides the different security models as a metric, which can then be used to make pertinent security decisions for securing wireless sensor network communication.

• Journal of the Korea Convergence Society
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• v.8 no.8
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• pp.27-32
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• 2017

The several wearable devices are not able to communicate through cable due to its portability. The wireless communication method is used because of its good communication quality and group action features when the several wearable devices communicate with each other. In this paper, we proposed the group decision algorithm for grouping display of the several wearable devices. It means that recognize as a group member after measuring distance in the wireless communication environment. The result of experience showed that the group-type display of several wearable devices method overcome the limit of the display of single wearable device.