• Journal of the Korea Institute of Information and Communication Engineering
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• v.27 no.1
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• pp.69-75
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• 2023

Small communication devices used in the Internet of Things are vulnerable to various hacking because they do not apply advanced encryption techniques due to their low memory capacity or slow computation speed. In order to increase the authentication reliability of small-sized transmitters operating in 433MHz band, we introduce an RF fingerprint and adopt a convolutional neural network (CNN) as a classification algorithm. The preamble signal transmitted by each transmitter are extracted and collected using software-defined-radio to constitute a training data set, which is used for training the CNN. We tested identification of 20 transmitters in four different scenarios and obtained high identification accuracy. In particular, the accuracy of 95.8% and 92.6% was obtained, respectively in the scenario where the test was performed at a location different from the transmitter's location at the time of collecting training data, and in the scenario where the transmitter moves at walking speed.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.9C
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• pp.836-841
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• 2002

Packet scheduling is an essential function to guarantee a quality of service by differentiating services in the Internet. Scheduling algorithms that have been suggested so far can be devided into Round-Robin methods and Fair Queueing methods Round-Robin methods have the advantage of high-speed processing through simple implementations, while Fair Queueing methods offer accurate services. Fair queueing algorithms, however, have problems of computational overheads and implementation complexity as their schedulers manage the states of every flow. This paper suggests a new method in which each flow performs the calculation in a distributed way to decide the service order. Our algorithm significantly reduces the scheduler's computational overheads while providing the same level of accuracy with the previous Fair Queueing algorithms.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.63 no.4
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• pp.570-574
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• 2014

This paper proposes a wireless digital endoscope with a ultra-wide-angle view. Two key components are implemented to demonstrate the feasibility of the proposed endoscope. First, a ultra-wide-angle lens module with the field of view of 144 degree and F-number of 2.2 is designed and manufactured. Second, a wireless module for a high-speed video transfer is implemented using a USB device server and wireless LAN router. The wireless module can directly transfer a streaming video to a computer with the resolution of 1920x1080, frame rate of 30 fps, and data rate of 53.3 Mbps without an internet connection. Since the wireless module supports two USB devices, two spots can be simultaneously observed using the proposed endoscope.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.39 no.8
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• pp.1-6
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• 2002

In this paper, we considered the CDMA/TDD system suitable for high-speed packet data transmission such as Internet and multimedia services, and a sequential decoding scheme which enables fast decoding and retransmission requirement. In addition, we Proposed an improved FANO algorithm, which adopts the competition path in order to reduce the number of revisit nodes. The conventional FANO algorithm suffered from the drawback of much more revisit nodes. Furthermore, we analyzed the performance of the CDMA/TDD system with the sequential decoding scheme we proposed over multipath channel.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.43 no.2 s.344
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• pp.1-6
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• 2006

This paper proposes association algorithm using load balancing for efficient AP selection under environment of wireless local area network(WLAN). Our scheme measures arrival time of association information when establishing the connection between access points and access terminal, analyzes the load condition of AP, and applies load balancing. AT selects and sets up low traffic AP by measuring traffic of connected access terminal, which can prevent over-franc of access points under hotspot environment that users access simultaneously. According to the above-described selection in a high speed wireless Internet service based on public WLAN technologies that are currently in operations. Further, it is possible to improve the efficiency of network management.

• Asia pacific journal of information systems
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• v.11 no.1
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• pp.1-24
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• 2001

This paper is aimed at proposing a new inference mechanism for B-to-B electronic commerce decision-makings, named IMITAO(Integer Matrix-driven Inference based on Transformed And-Or graph) which is based on integer matrix operation to speed up the inference. During the B-to-B electronic commerce, many kinds of negotiations are needed for mutually satisfactory decision-makings. During such negotiations, several factors including subjective and objective constraints should be considered so as to reach satisfactory decisions. In this respect, we suggest first a Transformed AND-OR Graph(TAOG) which each firm's conditions or judgement are incorporated into, and then we propose a high-speedy inference mechanism named IMITAO which basically depends on TAOG. Firms engaged in B-to-B negotiations on the Internet can get an appropriate decision support from using IMITAO for their negotiation simulations. The proposed IMITAO inference mechanism is characterized by its fast inference because its main inference procedures are based on integer matrix operation. A real-world example for B-to-B negotiations was used to prove the validity of our proposed TAOG and IMITAO approach. Experimental results showed that our approach was very useful in performing the B-to-B electronic commerce decision-makings considering a wide variety of either subjective or objective constraints.

• Proceedings of the KSRS Conference
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• 1999.11a
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• pp.165-170
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• 1999

Previous technology of remote sensing was focused on analyzing raster image and gaining information through image processing. But now it has extended to diverse fields like automatic map generation, material exploitation or monitoring environmental changes with effort to utilizing practical usage. And with rapid expansion of information exchange on Internet and high-speed network, the demand of public which want to utilize remotely sensed image has been increased. This makes growth of service on acquisition and processing remotely sensed image. GeoNet is a Java-based remotely sensed image processing system. It is based on Java object-oriented paradigm and features cross-platform, web-based execution and extensibility to client/server remotely sensed image processing model. Remotely sensed image processing software made by Java programming language can suggest alternatives to meet readily demand on remotely sensed image processing in proportion to increase of remotely sensed data. In this paper, we introduce GeoNet and explain its architecture.

• Journal of the Korea Computer Industry Society
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• v.2 no.4
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• pp.417-424
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• 2001

Internet networks consisting of existing routers show the limits in efficiency of traffic managements. In order to overcome the limits, MPLS System is high speed switching technology and is not based on IP address but based on label was designed. However MPLS system being based on ATM has the difficulties of supporting Qos(Quality of Service). This paper suggested the way to consist a service-assured-network using CR-LDP protocol which was designed for guaranteeing QoS in MPLS system being based on ATM switch and using qGSMP protocol, and the way to implicitly establish LSP by implementing QoS Translation and QoS Mapping in LER System.

• 한국정보통신설비학회:학술대회논문집
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• 2007.08a
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• pp.64-68
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• 2007

Commercial WiBro and 3G HSDPA services are launched last year in order to provide high speed wireless Internet access and multimedia service. Currently mobile communication service providers concentrate on the deployment of indoor mobile network since indoor traffic is remarkably increased. For fine indoor wireless communication, an installation of access point system via Public IP network which is called Femtocell is required. The development of indoor Femtocell system must be considered in the viewpoint of low hardware complexity, cost reduction, interlocking with WiBro/HSDPA network without change of network component and easy element management. In this paper, we review the implementation issue and technology of dual mode AP which provides WiBro and HSDPA signal to the user simultaneously. Especially, we describe on the HSDPA Femtocell standardization status and possible 3 types of HSDPA communication module development design. Furthermore we analyze the merits and demerits of each HSDPA Femtocell design type and propose a system which enables handover between indoor HSDPA Femtocell and outdoor commercial HSDPA mobile network.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.8 no.8
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• pp.1802-1809
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• 2004

This paper discusses cost allocation model of common facilities in voice and data traffic of mobile telephone network. There are several methods to be considered including traffic, facility, revenue, Ramsey, and benchmarking in local loop unbundling for High Speed Internet. It is important to investigate the strength and weakness of each method. This paper reviews the theoretical literatures and compares the characteristics of each methodology. Also, case studies are employed to get the implications concerned. As a result, in the beginning, it is desirable to introduce 50:50 allocation method used in local loop unbundling in UK. Then, it is recommendable to apply the ratio allocation method as the quantities of voice and data traffic become equal.