• Journal of the Institute of Electronics Engineers of Korea SD
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• v.41 no.5
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• pp.43-50
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• 2004

The clock skew is one of the major constraints for high-speed operation of synchronous integrated circuits. In this paper, we propose a hierarchical partitioning based clock network design algorithm called Advanced Clock Tree Generation (ACTG). Especially new effective partitioning and refinement techniques have been developed in which the capacitance and edge length to each sink are considered from the early stage of clock design. Hierarchical structures obtained by parhtioning and refinement are utilized for balanced clock routing. We use zero skew routing in which Elmore delay model is used to estimate the delay. An overlap avoidance routing algorithm for clock tree generation is proposed. Experimental results show significant improvement over conventional methods.

• International Journal of Computer Science & Network Security
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• v.23 no.7
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• pp.61-70
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• 2023

Image segmentation is a very crucial step in effective digital image processing. In the past decade, several research contributions were given related to this field. However, a general segmentation algorithm suitable for various applications is still challenging. Among several image segmentation approaches, graph-based approach has gained popularity due to its basic ability which reflects global image properties. This paper proposes a methodology to partition the image with its pixel, region and texture along with its intensity. To make segmentation faster in large images, it is processed in parallel among several CPUs. A way to achieve this is to split images into tiles that are independently processed. However, regions overlapping the tile border are split or lost when the minimum size requirements of the segmentation algorithm are not met. Here the contributions are made to segment the image on the basis of its pixel using min-cut/max-flow algorithm along with edge-based segmentation of the image. To segment on the basis of the region using a homogenous optimum cut algorithm with boundary segmentation. On the basis of texture, the object type using spectral partitioning technique is identified which also minimizes the graph cut value.

• Management Science and Financial Engineering
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• v.6 no.2
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• pp.29-45
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• 2000

We consider the design of a two-level telecommunication network having logical full-mesh/star topology, with the implementation of conduit systems taken together. The design problem is then viewed as consisting of three subproblems: locating hub facilities, placing a conduit network, and installing cables therein to configure the logical full-mesh/star network. Without partitioning into subproblems as done in the conventional approach, the whole problem is directly dealt with in a single integrated framework, inspired by some recent successes with the approach. We successfully formulate the problem as a variant of the classical multicommodity flow model for the fixed charge network design problem, aided by network augmentation, judicious commodity definition, and some flow restrictions. With our optimal model, we solve some randomly generated sample problems by using CPLEX MIP program. From the computational experiments, it seems that our model can be applied to the practical problem effectively.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.14 no.6
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• pp.675-685
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• 1989

The interconnection network is an integral part of parallel processing system. The multistage interconnection networks(MINs) have been the objects of intense research in recent years. In this paper, simulation techniques for circuit switchign MIN are extended to allow the performance evaluation of partitioned ADM/IADM network. Based on simulation data, the relationship between the netwrok performance, the partitioning scheme employed, and the conflict resolution strategies used within the network is enumerated. It is shown that IADM network coupled with the use of the hold strategy produces the best network operation in terms of RST (Request Service Time).

• IE interfaces
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• v.10 no.3
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• pp.179-187
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• 1997

The efficiency of material flow systems in terms of optimal network flow and minimum cost flow has always been an important design and operational goal in material handling and distribution system. In this research, an attempt was made to develop a new algorithm and the model to solve a stochastic material flow network with bidirectional and uncertain flows. A stochastic material flow network with bidirectional flows can be considered from a finite set with unknown demand probabilities of each node. This problem can be formulated as a special case of a two-stage linear programming problem which can be converted into an equivalent linear program. To find the optimal solution of proposed stochastic material flow network, some terminologies and algorithms together with theories are developed based on the partitioning and subgradient techniques. A computer program applying the proposed method was developed and was applied to various problems.

• KIPS Transactions on Software and Data Engineering
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• v.6 no.1
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• pp.1-8
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• 2017

Given a multi-dimensional dataset of tuples, a skyline query returns a subset of tuples which are not 'dominated' by any other tuples. Skyline query is very useful in Big data analysis since it filters out uninteresting items. Much interest was devoted to the MapReduce-based parallel processing of skyline queries in large-scale distributed environment. There are three requirements to improve parallelism in MapReduced-based algorithms: (1) workload should be well balanced (2) avoid redundant computations (3) Optimize network communication cost. In this paper, we introduce MR-SEAP (MapReduce sample Skyline object Equality Angular Partitioning), an efficient angular space partitioning based skyline query processing using sampling-based pruning, which satisfies requirements above. We conduct an extensive experiment to evaluate MR-SEAP.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.13 no.9
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• pp.4463-4483
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• 2019

Privacy-preserving collaborative filtering schemes take privacy concerns into its primary consideration without neglecting the prediction accuracy. Different schemes are proposed that are built upon different data partitioning scenarios such as a central server, two-, multi-party or peer-to-peer network. These data partitioning scenarios have been investigated in terms of claimed privacy promises, recently. However, to the best of our knowledge, any peer-to-peer privacy-preserving scheme lacks such study that scrutinizes privacy promises. In this paper, we apply three different attack techniques by utilizing auxiliary information to derive private ratings of peers and conduct experiments by varying privacy protection parameters to evaluate to what extent peers' data can be reconstructed.

• Journal of Korea Multimedia Society
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• v.6 no.7
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• pp.1256-1265
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• 2003

Content Delivery Network(CDN) is a mechanism to deliver multimedia content to end users on behalf of web content providers. Provider's content is distributed from content server to a set of delivery platforms located at Internet Service Providers(ISPs) through the CDN in order to realize better performance and availability than the system of centralized provider's servers. Existing work on CDN has primarily focused on techniques for efficiently multicasting the content from content server to the delivery platforms or to end users. Multimedia contents usually require broader bandwidth and accordingly WDM broadcast network has been highly recommended for the infrastructure network of CDN. In this paper, we propose methods for partitioning a multicast group into smaller subgroups using the previous status of receivers. Through the computer simulation, we show that proposed algorithm are useful to reduce the average receiver's waiting time and the number of transmissions.

• The KIPS Transactions:PartC
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• v.16C no.4
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• pp.521-526
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• 2009

Disruption/Delay Tolerant Network(DTN) is a technology for interconnecting partitioned networks. These days, DTN, especially routing in DTN, draws significant attention from the networking community. In this paper, we investigate DTN routing strategies for highly partitioned ad hoc networks where Unmanned Aerial Vehicles (UAVs) perform store-carry-forward functionality for improved network connectivity. Also we investigate UAV trajectory control mechanisms via simulation studies.

• Journal of Korean Society of Forest Science
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• v.81 no.4
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• pp.363-371
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• 1992

This study was aimed at developing a computer model to determine rational road networks in mountainous forests. The computer model is composed of two major subroutines for digital terrain analyses and route selection. The digital terrain model(DTM) provides various information on topographic and vegetative characteristics of forest stands. The DTM also evaluates the effectiveness of road construction based on slope gradients. Using the results of digital terrain analyses, the route selection subroutine, heuristically, determines the optimal road layout satisfying the predefined road densities. The route selection subroutine uses the area-partitioning method in order to fully of roads. This method leads to unbiased road layouts in forest areas. The size of the unit partitiones area can be calculated as a function of the predefined road density. In addition, the user-defined road density of the area-partitioning method provides flexibility in applying the model to real situations. The rational road network can be easily achived for varying road densities, which would be an essential element for network design of forest roads. The optimality conditions are evaluated in conjuction with longitudinal gradients, investment efficiency earthwork quantity or the mixed criteria of these three. The performance of the model was measured and, then, compared with those of conventional ones in terns of average skidding distance, accessibility of stands, development index and circulated road network index. The results of the performance analysis indicate that selection of roading routes for network design using the digital terrain analysis and the area-partitioning method improves performance of the network design medel.