• The KIPS Transactions:PartB
• /
• v.11B no.7 s.96
• /
• pp.841-848
• /
• 2004

Evolutionary a1gorithms are well-suited for multi-objective optimization problems involving several, often conflicting objectives. Pareto-based evolutionary algorithms, in particular, have shown better performance than other multi-objective evolutionary algorithms in comparison. However, generalized evolutionary multi-objective optimization algorithms have a weak point, in which the distribution of solutions are not uni-formly distributed onto Pareto optimal front. In this paper, we propose an evolutionary a1gorithm for multi-objective optimization which uses seed individuals in order to overcome weakness of algorithms Published. Seed individual means a solution which is not located in the crowded region on Pareto front. And the idea of our algorithm uses seed individuals for reproducing individuals for next generation. Thus, proposed a1go-rithm takes advantage of local searching effect because new individuals are produced near the seed individual with high probability, and is able to produce comparatively uniform distributed pareto optimal solutions. Simulation results on five testbed problems show that the proposed algo-rithm could produce uniform distributed solutions onto pareto optimal front, and is able to show better convergence compared to NSGA-II on all testbed problems except multi-modal problem.

• The KIPS Transactions:PartB
• /
• v.11B no.7 s.96
• /
• pp.803-812
• /
• 2004

The performance of video-on-demand(VOD) systems is known to be mainly dependent on a scheduling mechanism which they employ. Broadcast-based scheduling schemes have attracted a lot of attention as an efficient way of distributing popular videos to very large client populations. The main motivations of broadcasting scheduling mechanisms are that they scale up extremely well and they have very modest bandwidth requirements. This paper studies this issue and proposes a new broadcasting scheduling mechanism, named fast universal video dis-tribution(FUVD). FUVD scheme dynamically constructs a video broadcasting schedule in response to client requests, and broadcasts video seg-ments according to this schedule. This paper also evaluates the performance of FUVD on the basis of a simulation approach. The simulation results indicate that FUVD protocol shows a superior performance over UD, CBHD, and NPB in terms of the average response time.

• The KIPS Transactions:PartC
• /
• v.13C no.6 s.109
• /
• pp.701-708
• /
• 2006

Since different kinds of home network technologies coexist, seamless connections between different kinds of network protocols are essential for home computing environments. Several kinds of home network middleware have been developed and OSGi(Open Service Gateway Initiative) was initiated mainly for interoperability support with service distribution between various middleware environments. Framework, OSGi service platform, has weaknesses of passive service bundle management, user management and device management. Therefore, this paper resolves passive management parts which are critical weaknesses of OSGi Specification Version 3 and proposes SBM (Service Bundle Manager) to effiently manage various service bundles. Additionally, we verify practical effects of SBM through experiments.

• The KIPS Transactions:PartD
• /
• v.12D no.3 s.99
• /
• pp.471-480
• /
• 2005

Most questions made for remote examinations on web-based education system use methods of making questions using fixed questions or randomly using item pools or automatically using degree of difficulty. Particularly, automatically selection methods using degree of difficulty is the kernel of a question that objectivity of the first degree of difficulty for questions and an effective questions selection using degree of difficulty and mediateness degree of difficulty based result of examination. This paper is use automatically selection methods for examination on web-based education system. Firstly, we present new question selection algorithms as regards degree of difficulty and distribution between all units. Secondly, we present new algorithms of mediateness degree of difficulty as regards education ability of students for adjust the degree of difficulty. We identified this algorithms is more effective as compared with previously algorithms on web-based education system.

• The KIPS Transactions:PartA
• /
• v.10A no.4
• /
• pp.285-294
• /
• 2003

The request scheduling algorithms being used for the cluster web servers are mostly in two categories : load-balancing and contents-based cache affinity The goal of the load-balancing algorithms is to balance the loads between real servers. On the other hand, contents-based scheduling algorithm exploits the cache affinity in a way that the same type of requests are to be directed to a dedicated real server allowing load imbalance. So the performance comparison of the two algorithms is necessary, nevertheless the related experiment results are not much suggested. In this paper, performance evaluations have been done to compare the performance of the two scheduling algorithms. To accomplish this, we first implement a linux cluster web server, and then present the performance measurement results. The main contribution of this paper is to help the cluster web server administrators to select an algorithm fitting in with their circumstances from the two algorithms.

• The KIPS Transactions:PartD
• /
• v.11D no.5
• /
• pp.1197-1204
• /
• 2004

Rights process problem was stated among actors that participated in digital contents distribution while it was various type of digital content service. In order to solve it, It was expressed conceptual and technical elements by reflecting a system. Among them, the interoperability of metadata became a important issue. As for the metadata for contents service, necessity about standardization is stated as a basic framework composing a service system. This paper proposed the metadata element which focus on the rights process that is being a key factor of a DRM(Digital Right Management) system for digital comics contents service. Therefore, it was verified by using Context Model of MPEG-21 RDD with interoperability between metadata elements which developed a XML format and the existing MPEG-21 RDD elements. The study results will become basic materials in the system design that considered metadata element development and interoperability of digital contents of other field

• Journal of Communications and Networks
• /
• v.5 no.2
• /
• pp.157-166
• /
• 2003

This paper deals with the problem of channel identification for Single Input Multiple Output (SIMO) slow fading channels using clustering algorithms. Due to the intrinsic memory of the discrete-time model of the channel, over short observation periods, the received data vectors of the SIMO model are spread in clusters because of the AWGN noise. Each cluster is practically centered around the ideal channel output labels without noise and the noisy received vectors are distributed according to a multivariate Gaussian distribution. Starting from the Markov SIMO channel model, simultaneous maximum ikelihood estimation of the input vector and the channel coefficients reduce to one of obtaining the values of this pair that minimizes the sum of the Euclidean norms between the received and the estimated output vectors. Viterbi algorithm can be used for this purpose provided the trellis diagram of the Markov model can be labeled with the noiseless channel outputs. The problem of identification of the ideal channel outputs, which is the focus of this paper, is then equivalent to designing a Vector Quantizer (VQ) from a training set corresponding to the observed noisy channel outputs. The Linde-Buzo-Gray (LBG)-type clustering algorithms [1] could be used to obtain the noiseless channel output labels from the noisy received vectors. One problem with the use of such algorithms for blind time-varying channel identification is the codebook initialization. This paper looks at two critical issues with regards to the use of VQ for channel identification. The first has to deal with the applicability of this technique in general; we present theoretical results for the conditions under which the technique may be applicable. The second aims at overcoming the codebook initialization problem by proposing a novel approach which attempts to make the first phase of the channel estimation faster than the classical codebook initialization methods. Sample simulation results are provided confirming the effectiveness of the proposed initialization technique.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.14 no.10
• /
• pp.5156-5161
• /
• 2013

In distributed spatial data stream processing, processed tuples of downstream nodes are replicated to the upstream node in order to increase the utilization of distributed nodes and to recover the whole system for the case of system failure. However, while the data input rate increases and multiple downstream nodes share the operation result of the upstream node, the data which stores to output queues as a backup can be lost since the deletion operation delay may be occurred by the delay of the tuple processing of upstream node. In this paper, the adaptive upstream backup scheme based on operation throughput in distributed spatial data stream system is proposed. This method can cut down the average load rate of nodes by efficient spatial operation migration as it processes spatial temporal data stream, and it can minimize the data loss by fluid change of backup mode. The experiments show the proposed approach can prevent data loss and can decrease, on average, 20% of CPU utilization by node monitoring.

• The KIPS Transactions:PartD
• /
• v.19D no.2
• /
• pp.127-132
• /
• 2012

In the Seoul metropolitan bus network, it may be necessary for a bus passenger to pick up a parcel, which has been purchased through e-commerce, at his or her convenient bus stop on the way to home or office. The flow-capturing location-allocation model can be applied to select pickup points for such bus stops so that they maximize the captured passenger flows, where each passenger flow represents an origin-destination (O-D) pair of a passenger trip. In this paper, we propose a fast heuristic algorithm to select pickup points using a large O-D matrix, which has been extracted from five million transportation card transactions. The experimental results demonstrate the bus stops chosen as pickup points in terms of passenger flow and capture ratio, and illustrate the spatial distribution of the top 20 pickup points on a map.

• The KIPS Transactions:PartC
• /
• v.14C no.7
• /
• pp.553-558
• /
• 2007

In this paper, we introduce a set of structures and algorithms for communication efficient public key revocation in wireless sensor networks. Unlike the traditional networks, wireless sensor network is subjected to resources constraints. Thus, traditional public key revocation mechanisms such like the ordinary certificate revocation list is unsuitable to be used. This unsuitability is due to the huge size of required representation space for the different keys' identifiers and the revocation communication as the set of revoked keys grow. In this work, we introduce two communication-efficient schemes for the certificate revocation. In the first scheme, we utilize the complete subtree mechanism for the identifiers representation which is widely used in the broadcast encryption/user revocation. In the second scheme, we introduce a novel bit vector representation BVS which uses vector of relative identifiers occurrence representation. We introduce different revocation policies and present corresponding modifications of our scheme. Finally, we show how the encoding could reduce the communication overhead as well. Simulation results and comparisons are provided to show the value of our work.