• Journal of Communications and Networks
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• v.4 no.2
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• pp.118-127
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• 2002

This paper proposes a new scheme - parallel control scheme with feedback control (PCFC) for ABR services in ATM networks. The information from a source is split into a number of streams, for delivery over separate parallel connections with particular coding. At the receiver, the original information is reconstructed by the received packet from the parallel connections. The effects of PCFC on the network performance are due to two factors: Traffic splitting and load balancing. By combinations of analysis and simulation, this paper studies the implications of PCFC for how the ABR parameters should be scaled and the advantages of PCFC compared with other existing schemes.

• Journal of Ocean Engineering and Technology
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• v.27 no.4
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• pp.83-89
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• 2013

A numerical scheme based on a mode superposition method is presented for the dynamic response analysis of a top-tensioned riser (TTR) under sheared current loads. The natural frequencies and mode shapes of the TTR have been calculated analytically for a beam with a slowly varying tension and pinned-pinned boundary conditions at the top and bottom ends. The lift coefficients and corresponding amplitudes used to estimate the vortex-induced modal force and damping for each mode were predicted via iterative calculations based on the input and output power balancing concept. Here, the power-in regions were controlled by the normal distribution function, for which the center was coincident with the lock -in location by local vortex-shedding, and the range was defined by the constant standard deviation for the reduced velocity by the local current speed. Finally, dynamic responses such as root-mean-squared displacement and stress were calculated using the mode superposition technique. In order to verify the presented scheme, a numerical calculation was performed for a TTR under an arbitrary linearly sheared current and linearly varying tension. A comparison with the results of the existing software showed that the presented scheme could give reliable and feasible solutions. Case studies were performed to investigate the effects of various current loads and tensions.

• KIPS Transactions on Computer and Communication Systems
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• v.4 no.6
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• pp.177-184
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• 2015

This paper proposes a minimum-power scheduling scheme of real-time parallel tasks while meeting deadlines of the real-time tasks on DVFS-enabled multicore processors. The proposed scheme first finds a floating number of processing cores to each task so that the computation load of all processing cores would be equalized. Next the scheme translates the found floating number of cores into a natural number of cores while maintaining the computation load of all cores unchanged, and allocates the translated natural number of cores to the execution of each task. The scheme is designed to minimize the power consumption of the frequency-sharing multicore processor operating with the same processing speed at an instant time. Evaluation shows that the scheme saves up to 38% power consumption of the previous method.

• Journal of the Korea Society for Simulation
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• v.12 no.4
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• pp.51-59
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• 2003

Real-Time applications on Grid environment have several problems in terms of resource management addressed as follows; (1) dynamic resource allocation to provide QoS objectives, (2) heterogeneous resources that is different scale, or capacity in same unit, and (3) resource availability, and resource needs. This paper describes the techniques of resource manager (RM) handling above problems to support QoS of dynamic real-time applications on Grid. The contributions of this paper to solve problems are as follows: unification of dynamic resource requirements among heterogeneous hosts, control of resources in heterogeneous environments, and dynamic load balancing/sharing. Our heuristic allocation scheme works not only 257% better than random, 142% better than round robin, and 36.4% better than least load in QoS sensitivity, but also 38.6% better than random, 28.5% better than round robin, and 31.6% better than least load in QoS.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39A no.5
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• pp.280-292
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• 2014

Recently, heterogeneous networks consisting of small-cells on top of traditional macro-cellular network has attracted much attention, because traditional macro-cellular network is not suitable to support more demanding mobile data traffic due to its limitation of spatial reuse. However, due to the transmit power difference between macro- and small-cells, most users are associated with macro-cells rather than small-cells. To solve this problem, enhanced inter-cell interference coordination (eICIC) has been introduced. Particularly, in eICIC, the small-cell coverage is forcibly expanded to associate more users with small-cells. Then, to avoid cross-tier interference from macro-cells, these users are allowed to receive the data during almost blank subframe (ABS) in which macro-cells almost remain silent. However, this approach is not sufficient to balance the load between macro- and small-cells because it only expands the small-cell coverage. In this paper, we propose a load balance scheme improving proportional fairness for heterogeneous networks employing eICIC. In particular, the proposed scheme combines the greedy-based user association and the ABS rate determination in a recursive manner to perform the load balance.

• The KIPS Transactions:PartA
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• v.13A no.7 s.104
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• pp.615-622
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• 2006

Caching in a Wireless Internet Proxy Server Cluster Environment has an effect that minimizes the time on the request and response of Internet traffic and Web user As a way to increase the hit ratio of cache, we can use a hash function to make the same request URLs to be assigned to the same cache server. The disadvantage of the hashing scheme is that client requests cannot be well-distributed to all cache servers so that the performance of the whole system can depend on only a few busy servers. In this paper, we propose an improved load balancing scheme using hashing and Round Robin scheme that distributes client requests evenly to cache servers. In the existing hashing scheme, if a hashing value for a request URL is calculated, the server number is statically fixed at compile time while in the proposed scheme it is dynamically fixed at run time using round robin method. We implemented the proposed scheme in a Wireless Internet Proxy Server Cluster Environment and performed experiments using 16 PCs. Experimental results show the even distribution of client requests and the 52% to 112% performance improvement compared to the existing hashing method.

• The KIPS Transactions:PartC
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• v.15C no.5
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• pp.375-382
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• 2008

As the use of Internet and information communication technology is being generalized, the SSL protocol is essential in Internet because the important data should be transferred securely. While the SSL protocol is designed to defend from active attack such as message forgery and message alteration, the cipher suite setting can be easily modified. If the attacker draw on a malfunction of the client system and modify the cipher suite setting to the symmetric key algorithm which has short key length, he should eavesdrop and cryptanalysis the encrypt data. In this paper, we examine the domestic web site whether they generate the security session in the symmetric key algorithm which has short key length and propose the solution of the cipher suite setting problem.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.4
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• pp.2058-2074
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• 2017

Dense Heterogeneous Cellular Networks(HCNs) offer a promising approach to meet the target of 1000x increase in aggregate data rates in 5G wireless communication systems. However how to best utilize the available radio resources at densely deployed small cells remains an open problem as those small cells are typically unplanned. In this paper we focus on balancing loads across macro cells and small cells by offloading users to small cells, as well as dynamically switching off underutilized small cells. We propose a joint user association and base station(BS) sleep mangement(UA-BSM) scheme that proactively offloads users to a fraction of the densely deployed small cells. We propose a heuristic algorithm that iteratively solves the user association problem and puts BSs with low loads into sleep. An interference relation matrix(IRM) is constructed to help us identify the candidate BSs that can be put into sleep. User associations are then aggregated to selected small cells that remain active. Simulation results show that our proposed approach achieves load balancing across macro and small cells and reduces the number of active BSs. Numerical results show user signal to interference ratio(SINR) can be improved by small cell sleep control.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.25 no.2
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• pp.314-319
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• 2021

Problems that satisfy various constraints while maintaining weight balance in ships or aircraft were studied. In addition, a study was conducted to solve the problem with a mathematical method under the condition that the shape and weight of the load are the same and the m×n (m and n are all odd) mesh structures. The problem is that the existing mathematical weight balancing method is not suitable for circular structures. In this paper, we studied the load stowing problem in a circular space where objects are loaded at the vertices of N equilateral polygons. Assuming that all N conformal polygons have an even number of angles, it was proved that a loading method that always maintains weight balance regardless of the variety of number of loads. By providing the structure and loading method of the drone loading ship, we showed that our method was appropriate.

• Journal of KIISE:Computer Systems and Theory
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• v.29 no.8
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• pp.445-455
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• 2002

In this paper, we present a new task scheduling scheme ior the efficient execution of the tasks of compound nodes of hierarchical task graph(HTG) on shared memory system. The proposed scheme for exploitation functional parallelism is autoscheduling that performs the role of scheduling by processor itself without any dedicated global scheduler. To adapt the proposed scheduling scheme for various platforms, Including a uni-processor systems, Java threads were used for implementation, and the performance is analyzed in comparison with a conventional bit vector method. The experimental results showed that the proposed method was found to be more efficient in its execution time and exhibited good load-balancing when using the experimental parameter values. Furthermore, the memory size could be reduced when using the proposed algorithm compared with a conventional scheme.