• Journal of Korea Society of Digital Industry and Information Management
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• v.11 no.2
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• pp.67-72
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• 2015

As new Information technology such as IoT develops rapidly, a lot of changes are occurred in our lives. The Internet of Things is the network of physical objects or things embedded with electronics, software, sensors and connectivity to enable it to achieve greater value and service by exchanging data with the manufacturer, operator and/or other connected devices. This change is also applied to tourism industry. These days many people make a tour reservation using the internet. But it is required to consider the efficiency and security of tour reservation system. In this paper, we suggest a tour reservation system. First, we describe the computer reservation system, hotel reservation system and reservation system. Second, we perform the modeling of general reservation system and suggested reservation system. Third, performance evaluation is carried out with respect to efficiency and security. The results show that the suggested reservation system has a better performance than a general reservation system. At last we described the results and future works.

• International Journal of Internet, Broadcasting and Communication
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• v.12 no.4
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• pp.18-25
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• 2020

In the fifth generation (5G) and beyond 5G (B5G) mobile communication, non-orthogonal multiple access (NOMA) has attracted great attention due to higher spectral efficiency and massive connectivity. We investigate the impacts of the channel estimation errors on the bit-error rate (BER) of NOMA, especially with the single-user decoding (SUD) receiver, which does not perform successive interference cancellation (SIC), in contrast to the conventional SIC NOMA scheme. First, an analytical expression of the BER for SUD NOMA with channel estimation errors is derived. Then, it is demonstrated that the BER performance degrades severely up to the power allocation less than about 20%. Additionally, we show that for the fixed power allocation of 10% in such power allocation range, the signal-to-noise (SNR) loss owing to channel estimation errors is about 5 dB. As a consequence, the channel estimation error should be considered for the design of the SUD NOMA scheme.

• International Journal of Internet, Broadcasting and Communication
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• v.12 no.4
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• pp.204-211
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• 2020

The era of the 4th industrial revolution is a complex environment in which the cyber world and the physical world are integrated and interacted. In order to successfully implement and be sustainable the 4th industrial revolution of hyper-connectivity, hyper-convergence, and hyper-intelligence, not only the technological aspects that implemented digitalization but also the social aspects must be recognized and dealt with as important. There are socio-technical systems and socio-technical systems theory as concepts that describe systems involving complex interactions between the environmental aspects of human, mechanical and tissue systems. This study confirmed how the Socio-technical System was applied in the research literature for the last 10 years through machine learning-based analysis. Eight clusters were derived by performing co-occurrence keywords network analysis, and 13 research topics were derived and analyzed by performing a structural topic model. This study provides consensus and insight on the social and technological perspectives necessary for the sustainability of the 4th industrial revolution.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.12 no.6
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• pp.2619-2643
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• 2018

In this paper, a new clustering algorithm based on the connected region generation (CRG-clustering) is proposed. It is an effective and robust approach to clustering on the basis of the connectivity of the points and their neighbors. In the new algorithm, a connected region generating (CRG) algorithm is developed to obtain the connected regions and an isolated point set. Each connected region corresponds to a homogeneous cluster and this ensures the separability of an arbitrary data set theoretically. Then, a region expansion strategy and a consensus criterion are used to deal with the points in the isolated point set. Experimental results on the synthetic datasets and the real world datasets show that the proposed algorithm has high performance and is insensitive to noise.

• Proceedings of the IEEK Conference
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• 1998.10a
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• pp.15-18
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• 1998

Most existing FRADs support only permanent virtual circuit-based frame relay services. But several applications such as intranets, desktop video conferencing, remote access and voice applications typically do not require the dedicated bandwidth capabilities of PVCs because connections are only occasionally needed. So it drives the need of switched virtual circuit-based FRADs which offer potentail cost savings associated with dynamic bandwidth on demand connectivity. In this paper, we describe Frame Relay Network Access System(FNAS) that provides switched virtual circuit-based frame relay access for dial-up Internet services. The hardware configuration, software architecture and call processing flow of FNAS is explained.

• The Transactions of the Korea Information Processing Society
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• v.7 no.7
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• pp.2169-2178
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• 2000

This paper proposes the structure of an agent and rules for fault detection and location on LAN. To find out a reason of critical fault incurred LAN, collision detection rule, error detection rule, broadcast detection rule, system location rule, and Internet application location rule ar shown. Also, the structure of multi-agent system and state transition diagram is portrayed to have connectivity with he set of rules. To verify availability of proposed rules, the process to find a faulty system is shown by monitoring and analyzing the LAN fault occurrences from the proposed set of rules. Such an rule based agent system is helpful to an Internet manager to solve a reason of fault and make ad decision from gathering management information.

• IE interfaces
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• v.15 no.1
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• pp.20-25
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• 2002

In this research, a nameplate engraving system for images and texts downloaded through Internet on nameplate is developed. The system consists of two subsystems: thinning algorithm and NC code generation module. In the thinning algorithm, the concept of connectivity is used and center lines of images and texts, which will be used as NC tool paths, can be obtained successfully. Because the center lines are composed of a lot of pixels, NC code would be too long. In the NC code generation module, many useless pixel data are removed and linear interpolation algorithm is applied to only the remaining pixels. By performing actual experiments, the thinning algorithm and the NC code generation module are verified.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.12 no.3
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• pp.171-177
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• 2012

Network mobility support has been taken into consideration for users who have multiple terminals to enjoy the seamless connectivity. This paper proposes a network mobility support scheme in the LISP architecture. During the mobile router attachment, the EID-to-RLOC mapping database is refreshed in the map server. Furthermore, map update is developed to support smooth handoff for the mobile network. An analysis of performance is given by comparing the proposed scheme with NEMO.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.2 no.4
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• pp.171-183
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• 2008

Nowadays, wireless packet data services are provided over Wireless MAN (WMAN) at a high data service rate, while 3G cellular networks provide wide-area coverage at a low data service rate. The integration of mobile WiMAX and 3G networks is essential, to serve users requiring both high-speed wireless access as well as wide-area connectivity. In this paper, we propose a cross-layer optimization scheme for a vertical handover between mobile WiMAX and 3G cellular networks. More specifically, L2 (layer 2) and L3 (layer 3) signaling messages for a vertical handover are analyzed and reordered/combined, to optimize the handover procedure. Extensive simulations using ns-2 demonstrate that the proposed scheme enhances the performance of a vertical handover between mobile WiMAX and 3G networks: low handover latency, high TCP throughput, and low UDP packet loss ratio.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.7A
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• pp.781-785
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• 2004

Mobile IP maintains Internet connectivity while Mobile Hosts moving from one Internet attachment point to another. However, Mobile If is not appropriate for seamless mobility. Some micromobility protocols were proposed to complement Mobile IP by offering fast and seamless handoff control in limited geographical areas. In this paper, a new scheme, based on path prediction and resource reservation, is proposed to reduce the handoff latency by trying to eliminate the link setup time for fast handoff in all-IP wireless networks. Analytical results show that the proposed scheme offers shorter handoff delay and can improve the handoff efficiency.