• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.22 no.4
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• pp.67-72
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• 2022

This study presents the design of power amplifier (PA) in 60 nm GaN/Si HEMT technology. A customized transistor model enables the designing circuits operating at W-band. The all matching network of the PA was composed of equivalent transformer circuit to reduce matching loss. And then, equivalent transformer is several advantages without any additional inductive devices so that a wideband power characteristic can be achieved. The designed die area is 3900 ㎛ × 2300 ㎛. The designed results at center frequency achieved the small signal gain of 15.9 dB, the saturated output power (Psat) of 29.9 dBm, and the power added efficiency (PAE) of 24.2% at the supply voltage of 12 V.

• International journal of advanced smart convergence
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• v.12 no.3
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• pp.1-12
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• 2023

A public address (PA) system installed in a building is a system that delivers alerts, announcements, instructions, etc. in an emergency or disaster situation. As for the products used in PA systems, with the development of information and communication technology, PA products with various functions have been introduced to the market. PA systems recently launched in the market may be connected through a single network to enable efficient management and operation, or use voice recognition technology to deliver quick information in case of an emergency. In addition, a system capable of locating a user inside a building using a location-based service and guiding or responding to a safe area in the event of an emergency is being launched on the market. However, the new PA systems currently on the market add some functions to the existing PA system configuration to make system operation more convenient, but they do not change the complex PA system configuration to reduce facility costs, maintenance, and management costs. In this paper, we propose a novel PA system configuration for buildings using audio networks and control hierarchy over peer-to-peer (Anchor) technology based on audio over IP (AoIP), which simplifies the complex PA system configuration and enables convenient operation and management. As a result of the study, through the emergency signal processing algorithm, fire broadcasting was made possible according to the detection of the existence of a fire signal in the Anchor system. In addition, the control device of the PA system was replaced with software to reduce the equipment installation cost, and the PA system configuration was simplified. In the future, it is expected that the PA system using Anchor technology will become the standard for PA facilities.

• The Journal of Korean Association of Computer Education
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• v.16 no.2
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• pp.69-78
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• 2013

For the increasingly complicated and technology dependent 21st century, ICT literacy is being emphasized by education authorities as a key ability needed to succeed in a knowledge-based society. Accordingly, since 2007, several studies have been conducted to measure the ICT literacy levels of students. This study aimed at analyzing how ICT literacy levels vary according to students' skill sets from the viewpoint of educational convenience. To fulfill this goal, the ICT literacy abilities of 167 elementary students and 159 middle school students (all receiving education at "gifted students" education centers) were compared with the following results. First, elementary students displayed differences with regards to 'computer and network' and 'information society and ethics' among the content elements, and 'critical mind' and 'information communication' among capability elements according to their skill sets. Second, middle school students displayed differences with regards to 'information society and ethics' and 'information organization and creation' elements according to their skill sets. The significance of this study lies in the fact that it measured the ICT literacy levels of --and made suggestions for education to-- students specially gifted in information, science and mathematics rather than general students.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.43 no.5 s.347
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• pp.113-120
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• 2006

This thesis deals with solutions such as coverage area extension, reduction of the shadow region and performance enhancement of handover caused by structural modification of WiBro network. The More far the distance of RAS(Radio Access Station) and SS(Subscriber Station) is in micro cell, the more bad the quality of channel environment becomes owing to radio interference. Consequently, it causes the deterioration of the throughput and also the deterioration of communication quality in many sides. In fact, most users of WiBro are located in the region, the QPSK region which is bad in point of channel quality. It brings the service complaint by user. We select RS(relay station) to solve the matter caused by channel environment in this cell, and extend coverage and improve the performance of handover call blocking.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.5
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• pp.937-941
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• 2016

This paper proposed an efficient multiple TCP mechanism using Android smartphones for remote control video Wi-Fi stream transmission via network communications in real time. The wireless video stream transmission mechanism can be applied in various area such as real time server stream transmissions, movable drones, disaster robotics and real time security monitoring systems. Moreover, we urgently need to transmit data in timely fashion such as medical emergency, security surveillance and disaster prevention. Our parallel TCP transmission system can play an important role in several area such as real time server stream transmissions, movable drones, disaster robotics and real time security monitoring systems as mentioned in the previous sentence. Therefore, we designed and implemented a parallel TCP transmission (parallel stream) for an efficient real time video streaming services. In conclusion, we evaluated proposed mechanism using parallel TCP transmission under various environments with performance analysis.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.7
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• pp.1313-1319
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• 2017

In this paper, we evaluate the performance of multi-hop transmissions in IEEE 802.15.6 ultra wide band (UWB) wireless body area network (WBAN). The packet structure in the physical layer, and encoding and decoding are considered for multi-hop transmissions in IEEE 802.15.6 UWB WBAN. We analyze the data success rate and energy efficiency of multi-hop transmissions with considering the length of data payload, transmission power, and distances between the nodes in IEEE 802.15.6 UWB WBAN. Through simulations, we evaluate the data success rate and energy efficiency of multi-hop transmissions with varying the length of data payload, transmission power, and distances between the nodes in IEEE 802.15.6 UWB WBAN. Finally, we can select an energy-efficient multi-hop transmission in IEEE 802.15.6 UWB WBAN depending on the length of data payload, transmission power, and distances between the nodes.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.9
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• pp.1999-2007
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• 2010

Proxy Mobile IPv6(PMIPv6) is a network-based mobility management protocol and it does not require mobile node's involving in mobility management. In PMIPv6, the Mobile Access Gateway (MAG) incurs a high signaling cost to update the location of a mobile node to the remote Local Mobility Anchor (LMA) if it moves frequently. It may cause excessive signaling traffic and increase a high traffic load on LMA. Therefore, we propose a new mobility management scheme in proxy mobile IPv6 networks with dynamic paging support. To minimize signaling overhead, in our proposal, the size of the paging area is determined dynamically according the changes of mobility and traffic patterns of the mobile node. An analytic model is applied to determine the optimal size of the paging area. The cost analysis using fluid flow model presented in this paper shows that our proposal can achieve performance superior that of PMIPv6 scheme.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37B no.12
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• pp.1119-1127
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• 2012

The one of features of M2M communications, which are recently attracted attention as a future business of mobile communications, is that there is a large number of devices compared with traditional communication services. Hence, the control signal that are generated by the M2M devices may cause a significant congestion in the network and in order to solve this problem, a standardization is progressing for reducing the redundant signaling by managing M2M devices as a group in 3GPP standardization. In this paper, we propose a method of group based mobility management by managing M2M devices that have the same mobility as a group. In the proposed method, M2M devices that have the same mobility are grouped by the Mobility Management Entity (MME) and the MME elects a group header among the M2M devices in the group. Then, the group header performs the Tracking Area Update (TAU) on behalf of the group members to reduce the signaling overhead of mobility management. With the proposed method, we can achieve 80% decrease of the signaling overhead of mobility management compared with the case where each M2M device individually performs its TAU procedure.

• Journal of Convergence Society for SMB
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• v.1 no.1
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• pp.29-37
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• 2011

As the area of informatization has been expanding followed by the development of information communication technology, cloud computing which can use infra sources like server, storage, and network in IT area as an efficient service whenever and wherever skyrockets. But users who use cloud computing technology may have some problems like exposure personal data, surveillance on person, and process on commercial purpose on their personal data. This paper proposes a security technique which protect user's privacy by creating imaginary user information not to be used by other people. The proposed technique virtualizes user's information as an anonymity value not to let other people know user's identity by combining PIN code with it and guarantees user's anonymity. Also it can manage and certificate personal information that is important in cloud computing, so that it can solve security problem of cloud computing which centers all informations. Therefore this paper can assist upgrading of the level of information of poor SMBs through safe use of cloud computing.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.9C
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• pp.922-927
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• 2009

Utilization problem of the limited spectrum is the one of the most important issues in wireless communication systems. Cognitive radio technique which is finding and utilizing frequency holes is also one of those techniques. Specially, the spectrum sensing technique to detect the primary user signal is a core technology in cognitive radio area. In this paper, we propose the spectrum sensing algorithm using Bussgang theorem. The proposed algorithm calculates the statistical difference between the Gaussian noise and the primary user signal by applying Bussgang theorem to the received signal. The algorithm is not affected by noise uncertainty and can detect the primary user signal in the very low SNR environment. We evaluate the algorithm through computer simulations with 12 ATSC A/74 DTV signal captures based on IEEE 802.22 WRAN and formulate the sensing threshold for the proposed scheme.