• Proceedings of the IEEK Conference
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• 2002.07b
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• pp.723-726
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• 2002

This paper describes the design, fabrication, and measurement of a sequential-rotation microstrip-array antenna for the Electronic Toll Collection System (ETCS). The ETCS is made possible by using roadside equipment with radiation pattern that can accurately pinpoint the designated communication area, without interference from other lanes. The sequential-rotation microstrip-array antenna was applied to the absorber to reduce the side lobe level (SLL). Results showed that the antenna yields a return loss at a center frequency of -20.675 dB, an axial ratio of 1.15 dB, and a gain of 20.26 dBi.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.1 no.1
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• pp.105-111
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• 1997

This Paper Proposes a new efficient system design strategies for the acoustic-based underwater multiple modem and media access control protocol. The system aims to establish the acoustic-based communication network of an underwater vehicles for deep sea mining, which ensures a certain level of maximum throughput regardless of the propagation delay of acoustic and allows fast data transmission through the acoustic-based multiple channel. A media access control protocol for integrated communication network and it's acoustic-based communication modems that allows 'peer-to-peer' communication between a surface mining plant multiple underwater system is designed, and the proposed media access control protocol is implemented for its verification. Furthermore, a proposed design strategies which make it possible to control the multiple vehicle for an underwater mining is presented in this paper.

• ETRI Journal
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• v.36 no.4
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• pp.625-634
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• 2014

This paper studies a dual-hop multiple-access relay network where two independent source nodes transmit information to a common destination node with the aid of multiple single-antenna amplify-and-forward relays. Each relay node is subject to an individual power constraint. We focus on the design of distributed beamforming schemes for the relays to support the transmission rate requirements of the two sources. To this end, we first characterize the achievable rate region for this network via solving a sequence of corner point optimization problems proposed in this paper. We also develop several low-complexity suboptimal schemes in closed form. Two inner bounds of the achievable rate region are theoretically shown to be approximately optimal in two special scenarios. Finally, numerical results demonstrate the effectiveness of our proposed approaches.

• Proceedings of the IEEK Conference
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• 1999.11a
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• pp.939-942
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• 1999

In this paper, Tele-Test System for ASIC Design is constructed. It consists of the server, and the clients. The server and clients are implemented by Java. Using Java RMI system, the remote access via information network is implemented. In this Tele-test system, fault simulation, test pattern compaction, test pattern generation, and path-delay fault test generation services are implemented. All service can be peformed parallel by network access.

• The Transactions of the Korea Information Processing Society
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• v.6 no.11S
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• pp.3190-3198
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• 1999

Because of the rapid growth of the mobile communication, the need for the mobile internet access has grown up as well. since the current mobile communication network, however, is optimized for a voice communication system, which exclusively occupies a channel for a given time, it is not suitable for variable rate packet data. In order to support the mobile internet access, it is essential do design a reasonable packet switching network which supports the mobility. Since mobile packet network has longer latency, high speed switching and QoS are required to meet the user's requirements. In this paper, we suggest an resonable way to construct a network and its operation procedures utilizing GPRS(General Packet Radio Service) network and MPLS(Multi Protocol Label Switching) to provide a high speed switching and QoS mobile internet access. GPRS is used as a network which supports the mobility and MPLS guarantees the QoS and high speed IP protocol transmission based on the ATM switching technology.

• Journal of Industrial Technology
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• v.28 no.B
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• pp.245-250
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• 2008

Recently, mobile devices have supported wireless LAN as well as bluetooth, where the services such as heterogeneous network access and seamless mobility connection are important. Even though the mobility and physical network might be varied, an efficient communication mechanism for the network access and a robust mobility management of mobile devices are needed. In this paper, we design and implement a Bluetooth system with mobile LAN access capability. The proposed system has the following features; 1) IP connection is enabled by BENP in the link layer, 2) The networks devices of heterogeneous mobile devices are integrated into a single virtual network interface, 3) IP mobility between the bluetooth and wireless LAN is supported by mobile IP. The experimented results show that the packet loss and delay time during the handover duration is reduced by predicting the handover among different networks followed by the setup of any required parameters in advance.

• Journal of Convergence Society for SMB
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• v.6 no.3
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• pp.29-35
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• 2016

This paper presents the design of a user authentication system (DCIAS) using the device constant information. Defined design a new password using the access device constant information to be used for user authentication during system access on the network, and design a new concept the user authentication system so that it can cope with the threat required from passive replay attacks to re-use the password obtained in other applications offer. In addition, by storing a password defined by the design of the encrypted random locations in the server and designed to neutralize the illegal access to the system through the network. Therefore proposed using the present system, even if access to the system through any of the network can not know whether any where the password is stored, and if all right even stored information is not easy to crack's encrypted to neutralize any replay attacks on the network to that has strong security features.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.9 no.11
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• pp.4331-4346
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• 2015

The femtocell network, which is designed for low power transmission and consists of consumer installed small base stations, coexists with macrocells to exploit spatial reuse gain. For its realization, cross-tier interference mitigation is an important issue. To solve this problem, we propose a joint access and power control scheme that requires limited information exchange between the femto and macro networks. Our objective is to maximize the network throughput while satisfying each user's quality of service (QoS) requirement. To accomplish this, we first introduce two distributed interference detection schemes, i.e., the femto base station and macro user equipment based schemes. Then, the proposed scheme dynamically adjusts the transmission power and makes a decision on the access mode of each femto base station. Through extensive simulations, we show that the proposed scheme outperforms earlier works in terms of the throughput and outage probability.

• Journal of the Korea Society of Computer and Information
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• v.11 no.1 s.39
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• pp.167-176
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• 2006

In this paper, a home network access agent, which controls and monitors networked appliances at home using various terminals regardless of user's location, is designed and implemented. The proposed access agent integrates wire and wireless network on a home gateway (or home server) and is accessed with consistent messages using various terminals such as a web terminal, a PDA and a cellular phone. Also, in order to verify the operation and availability of the agent, a user interface for the various terminals is designed and a home network testbed which is accessed and controlled by the terminals is implemented.

• Journal of Communications and Networks
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• v.6 no.4
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• pp.317-330
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• 2004

In this paper, we explore the utility of recently discovered multiple-antenna techniques (namely MIMO techniques) for medium access control (MAC) design and routing in mobile ad hoc networks. Specifically, we focus on ad hoc networks where the spatial diversity technique is used to combat fading and achieve robustness in the presence of user mobility. We first examine the impact of spatial diversity on the MAC design, and devise a MIMO MAC protocol accordingly. We then develop analytical methods to characterize the corresponding saturation throughput for MIMO multi-hop networks. Building on the throughout analysis, we study the impact of MIMO MAC on routing. We characterize the optimal hop distance that minimizes the end-to-end delay in a large network. For completeness, we also study MAC design using directional antennas for the case where the channel has a strong line of sight (LOS) component. Our results show that the spatial diversity technique and the directional antenna technique can enhance the performance of mobile ad hoc networks significantly.