• The Journal of Korean Association of Computer Education
• /
• v.12 no.2
• /
• pp.77-86
• /
• 2009

Large-scale applications, that needs large-capacity R&D resources and realtime data transmission, have demanded more stable and high-performance network environment than current Internet environments. Recently, global R&D networks have focuses on utilizing Lambda networking technologies and resource reservation systems to be satisfied with various applications' requirements. In this paper, we modify the existing DRS (Dynamic Right-Sizing) model to reflect various advantages in terms of the stability and high-capacity of Lambda network. In addition, we suggest the design methodology of high-performance Lambda network, which can integrate NRPS (Network Resource Provisioning System) into our modified DRS model.

• Journal of Communications and Networks
• /
• v.18 no.4
• /
• pp.639-648
• /
• 2016

Next-generation (4G) systems are designed to support universal frequency reuse (UFR) to achieve best use of valuable spectra. However, it leads to undesirable interference level near cell borders. To control this, 4G systems adopt techniques, such as network multiple-input multiple-output (MIMO) and inter-cell interference coordination (ICIC), to improve cell-edge throughput. Network MIMO aims at mitigating inter-cell interference towards cell-edge users (CEUs) through multi-cell cooperation, where each collaborative base station serves both cell-center users (CCUs) and CEUs, including other cells' CEUs, under a power constraint. The present ICIC strategies cannot be directly applied to network MIMO because they were designed in absence of multi-cell coordination. In the presence of network MIMO, this paper investigates antenna orientations in ICIC and the method of power management. Results show that a proper antenna orientation can improve the cell-edge capacity and meantime lower the interference to CCUs. Capacity inconsistency between CCUs and CEUs is detrimental to mobile communications. Simulation results show that the proposed power management for ICIC in network MIMO systems can achieve a uniform data rate regardless users' position.

• Proceedings of the Korean Institute of Communication Sciences Conference
• /
• 2006.07a
• /
• pp.555-555
• /
• 2006

• Korean Management Science Review
• /
• v.17 no.1
• /
• pp.17-30
• /
• 2000

This paper addresses the effect of protective capacity on the lead time and throughput of a re-entrant line where statistical fluctuations exist in the form of variation in processing times and machine breakdowns. The specific framework employed in the paper is a five station re-entrant line structured as a closed network mode. This paper argues that protective capacity can be used in conjunction with WIP inventory in order to reduce the lead time and to increase the increase the throughput of a line. Simulation analyses are included to give insight into the effectiveness of protective capacity.

• IE interfaces
• /
• v.16 no.2
• /
• pp.195-200
• /
• 2003

In this paper, the selective use of RTS and CTS frames is considered to analyze the capacity of IEEE 802.11 WLAN (Wireless Local Area Network). The RTS and CTS frames are used to transmit the data frames longer than dot11RTSThreshold according to IEEE 802.11 specification. The analysis of the optimal RTS-CTS threshold is derived to maximize the capacity of IEEE 802.11 WLAN. And, numerical examples are also presented for IEEE 802.11 a and b WLANs.

• Journal of Electrical Engineering and Technology
• /
• v.13 no.2
• /
• pp.733-741
• /
• 2018

Capacity estimation is indispensable to ensure the safety and reliability of lithium-ion batteries in electric vehicles (EVs). Therefore it's quite necessary to develop an effective on-board capacity estimation technique. Based on experiment, it's found constant current charge time (CCCT) and the capacity have a strong linear correlation when the capacity is more than 80% of its rated value, during which the battery is considered healthy. Thus this paper employs CCCT as the health indicator for on-board capacity estimation by means of relevance vector machine (RVM). As the ambient temperature (AT) dramatically influences the capacity fading, it is added to RVM input to improve the estimation accuracy. The estimations are compared with that via back-propagation neural network (BPNN). The experiments demonstrate that CCCT with AT is highly qualified for on-board capacity estimation of lithium-ion batteries via RVM as the results are more precise and reliable than that calculated by BPNN.

• The KIPS Transactions:PartC
• /
• v.10C no.5
• /
• pp.635-640
• /
• 2003

Due to the development of information technology and widespread use of telecommunications networks, the design of mesh-survivable net works has received considerable attention in recent years. This paper deals with spare capacity planning scheme in mesh-based fiber-optic networks. In this study, a new spare capacity planning scheme is proposed utilizing path restoration with maximal sharing of share capacity that is traced by the spare capacity incremental factor (after this, we called "SCIF"). We compare it with three other spare capacity planning scheme : link capacity of IP (Integer Programming), SLPA(Spare Link Placement Algorithm) and GA(Genetic Algorithm). The approach shows better performance with heuristics algorithm for determining the spare capacity assignment and the computational time is easily controlled allowing the approach to scale to large networks. The major advantages of the new approach are reduction of spare capacity and a polynomial time complexity.omplexity.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
• /
• v.6 no.4
• /
• pp.216-223
• /
• 2013

As the fast growth of using Internet, the requests of clients having different types and pressing loads on the server have been increased in World Wide Web. Thus the interesting issue is how to measure the real capacity of a Web Server. There have been much recent studies about measuring the capacity of web server. But the cause of Server response time delay is not just server itself but also network packet loss. To measure the practical capacity of web server, we generate scalable clients using Posix Thread, transport packets which were generated by scalable clients to the server using UDP and receive the packets which were the remain packet from network packet loss using TCP. In this paper, we propose a method to measure the practical capacity of a web server using the Scalable Clients based on Posix Thread and the transport on Application level.

• Journal of Electrical Engineering and Technology
• /
• v.9 no.4
• /
• pp.1163-1170
• /
• 2014

Due to global environmental regulations and policies with rapid advancement of renewable energy technologies, the development type of renewable energy sources (RES) in power systems is expanding from small-scale distributed generation to large-scale grid-connected systems. In the near future, it is expected that RES achieves grid parity which means the equilibrium point where the power cost of RES is equal to the power costs of conventional generators. However, although RES would achieve the grid parity, the cost related with development of large-scale RES is still a big burden. Furthermore, it is hard to determine a suitable capacity of RES because of their output characteristics affected by locations and weather effects. Therefore, to determine an optimal capacity for RES becomes an important decision-making problem. This study proposes a method for determining an optimal installed capacity of RES from the business viewpoint of an independent power plant (IPP). In order to verify the proposed method, we have performed case studies on real power system in Incheon and Shiheung areas, South Korea.

• Steel and Composite Structures
• /
• v.39 no.3
• /
• pp.319-335
• /
• 2021

This study proposes a new and highly-accurate artificial intelligence model, namely ANN-IP, which combines an interior-point (IP) algorithm and artificial neural network (ANN), to improve the axial compression capacity prediction of elliptical concrete-filled steel tubular (CFST) columns. For this purpose, 145 tests of elliptical CFST columns extracted from the literature are used to develop the ANN-IP model. In this regard, axial compression capacity is considered as a function of the column length, the major axis diameter, the minor axis diameter, the thickness of the steel tube, the yield strength of the steel tube, and the compressive strength of concrete. The performance of the ANN-IP model is compared with the ANN-LM model, which uses the robust Levenberg-Marquardt (LM) algorithm to train the ANN model. The comparative results show that the ANN-IP model obtains more magnificent precision (R² = 0.983, RMSE = 59.963 kN, a20 - index = 0.979) than the ANN-LM model (R² = 0.938, RMSE = 116.634 kN, a20 - index = 0.890). Finally, a new Graphical User Interface (GUI) tool is developed to use the ANN-IP model for the practical design. In conclusion, this study reveals that the proposed ANN-IP model can properly predict the axial compression capacity of elliptical CFST columns and eliminate the need for conducting costly experiments to some extent.