• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.7
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• pp.2972-2991
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• 2016

WLAN is the best choice in the place where complex network is hard to set up. Intelligent terminals are more and more assembled in some areas now. However, according to IEEE 802.11n/802.11ac, the access-point (AP) can only serve one user at a single frequency channel. The spectrum efficiency urgently needs to be improved. In theory, AP with multi-antenna can serve multiple users if these users do not interfere with each other. In this paper, we propose a user clustering scheme that could achieve multi-user selection through the mutual cooperation among users. We focus on two points, one is to achieve multi-user communication with multiple antennas technique at a single frequency channel, and the other one is to use a way of distributed users' collaboration to determine the multi-user selection for user clustering. Firstly, we use the CSMA/CA protocol to select the first user, and then we set this user as a source node using users' cooperation to search other proper users. With the help of the users' broadcast cooperation, we can search and select other appropriate user (while the number of access users is limited by the number of antennas in AP) to access AP with the first user simultaneously. In the network node searching, we propose a maximum degree energy routing searching algorithm, which uses the shortest time and traverses as many users as possible. We carried out the necessary analysis and simulation to prove the feasibility of the scheme. We hope this work may provide a new idea for the solution of the multiple access problem.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.9
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• pp.1627-1634
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• 2017

In this work, a junctionless transistor with different film thickness of amorphous InGaZnO has been fabricated and it's instability has been analyzed with different film thickness under positive and negative gate stress as well as light illumination. It was found that the threshold voltage shift and the variation of drain current have been increased with decrease of film thickness under the condition of gate stress and light illumination. The reasons for the observed results have been explained by stretched-exponential model and device simulation. Due to the reduced carrier trapping time with decrease of film thickness, electrons and holes can be activated easily. Due to the increase of vertical channel electric field reaching the back interface with decrease of film thickness, more electrons and holes can be accumulated in back interface. When one decides the film thickness for the fabrication of junctionless transistor, the more significant device instability with decrease of film thickness should be consdered.

• Proceedings of the Korean Magnestics Society Conference
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• 2005.06a
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• pp.128-129
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• 2005

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.12 no.6
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• pp.65-73
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• 2012

Wrist wearable device for the measurement of pulse rate, ECG, and activity during normal daily life, which could be used for the continuous monitoring and remote transmission of acquired data, was developed. Pressure sensor, device attached electrodes, and 3-degree accelerometer were used. Analysis algorithm and firmware program were established for providing diagnostic information for the users. Results of this study, possible for the management of health report and transmission of the results through bluetooth by wearing simple personal wrist device, could be used for the development of portable device in the u-healthcare environment.

• JSTS:Journal of Semiconductor Technology and Science
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• v.5 no.3
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• pp.159-167
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• 2005

Quantization effects (QEs), which manifests when the device dimensions are comparable to the de Brogile wavelength, are becoming common physical phenomena in the present micro-/nanometer technology era. While most novel devices take advantage of QEs to achieve fast switching speed, miniature size and extremely small power consumption, the mainstream CMOS devices (with the exception of EEPROMs) are generally suffering in performance from these effects. In this paper, an analytical model accounting for the QEs and poly-depletion effects (PDEs) at the silicon (Si)/dielectric interface describing the capacitance-voltage (C-V) and current-voltage (I-V) characteristics of MOS devices with thin oxides is developed. It is also applicable to multi-layer gate-stack structures, since a general procedure is used for calculating the quantum inversion charge density. Using this inversion charge density, device characteristics are obtained. Also solutions for C-V can be quickly obtained without computational burden of solving over a physical grid. We conclude with comparison of the results obtained with our model and those obtained by self-consistent solution of the $Schr{\ddot{o}}dinger$ and Poisson equations and simulations reported previously in the literature. A good agreement was observed between them.

• The Journal of the Korea institute of electronic communication sciences
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• v.13 no.5
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• pp.1017-1022
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• 2018

In this paper, a single house fire alarm device, which can solve the problem of fire perception at midnight time and the attenuation of alarm signal due to the wall between rooms based on the wireless communication, was developed. The radio controlled fire alarm device was designed to allow fire to be recognized quickly and accurately by monitoring the temperature and $CO_2$ concentration based on the temperature sensor and gas sensor, by detecting the fire in the house and by transmitting the fire alarm to the individual wireless alarms of other rooms using the wireless transmission/reception module. Using the Arduino as a main control device, three independent fire alarm device prototypes were made, and their usefulness was verified by the correct operations in temperature and gas tests.

• The Journal of the Korea institute of electronic communication sciences
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• v.16 no.5
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• pp.835-844
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• 2021

In this paper, a power facility communication control device was designed to autonomously determine and separate the fault section through communication between power facilities in the smart grid distribution system. In the power facility communication control device, the control module was designed as a DSP to measure three-phase voltage and current, and the communication module was designed as an embedded-based Raspberry Pi to determine the fault section and realize the fault section separation through communication between power facilities. Communication between DSP and Raspberry Pi was designed by SPI communication, and communication between Raspberry Pi was designed based on Wi-Fi. Finally, a performance evaluation system based on three power facility communication control devices was built, and simulation verification was conducted for various fault events that may occur on the distribution line. As a result of the test evaluation, it was possible to confirm the effectiveness of the design methodology of the communication control device by showing the required response of the communication control device to all test cases.

• International Journal of Advanced Culture Technology
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• v.10 no.2
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• pp.194-200
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• 2022

Traditionally, postal services that produce and deliver paper-based notices have been the mainstream. The reason is that it has the function of distribution and proof of delivery in the postal delivery system as well as the advantage of information delivery through postal delivery. After all, for the purpose of distribution and proof of delivery, many organizations use paper-based postal notices. However, in recent years, it has been in the spotlight to produce a paper-based postal notice as an electronic notice and deliver information to a mobile device through the Internet. In this paper, we propose a safe interworking method for user identification information required for private institutions to transmit mobile electronic notices. In order for a private institution to accurately deliver an electronic notice to a mobile service subscriber, a means to confirm whether the private institution and the mobile device subscriber are the same person is required. In the mobile electronic notification service, the connecting information provided by the personal identity proofing agency is used as a means of user identification. Connecting information is called a resident registration number on the Internet and is one-way hash information that can only be created by the personal identity proofing agency designated by the government. In order to transmit a mobile electronic notice, it is necessary to share connecting information for the same user identification between the institution that requests the sending of the electronic notice and the institution that processes the sending of the electronic notice. Connecting information is personal information that can uniquely identify a user, and if it is disclosed, damage such as personal information infringement may occur. As such, it is necessary to prevent problems that may arise from misuse and abuse of connecting information as well as increase in the benefits of sending the mobile electronic notice. In this paper, a safe and effective mobile electronic notification service can be performed by suggesting a method for safe interworking of information related to the mobile electronic notification service.

• International Journal of Internet, Broadcasting and Communication
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• v.12 no.2
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• pp.77-82
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• 2020

IoT devices frequently require input resources to communicate with various sensors or IoT platforms. IoT device wastes a lot of time as idle time or waiting time to check the data of the input resource and use the input resource. In addition, IoT devices use various input resources. We compares and analyzes input idle time and input waiting time generated from hardware serial input resource, software serial input resource, digital port input resource, and analog port input resource using Arduino widely used as IoT device. In order to design the IoT device framework, it is necessary to understand the characteristics of input resources and to design them to minimize unnecessary input idle time and input waiting time. The analog input wait time has a much larger input wait time than the digital input wait time, so it must be designed to receive analog information periodically at the appropriate timing. The characteristics of the input resources analyzed in this way help to design an efficient IoT device.

• Journal of Institute of Control, Robotics and Systems
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• v.11 no.8
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• pp.733-739
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• 2005

Device Description that is described as C-based DDL(Device Description Language) should be provided for the control system to use the progressive function of field device in the distributed control system. DD expresses field device function itself and parameter. DD is used to set a necessary function far a control strategy in the central control system. DD technology which was adopted as international standard IEC 61804-Part 2 is being used in PROFIBUS, Foundation Fieldbus and HART. However, the DD is dependent to the fieldbus and it doesn't have a suitable form in the industrial Ethernet. This paper presents the possibility of a change from EDD(Electronic Device Description) and GSD(General Slave Data) used for integrating field devices to XDD(XML for Device Description) and verifies it's effectiveness. Also, this paper presents research assignment on the XML application in the distributional system from now on by examining the possibility of Ethernet`s development in the industrial area.