• The Transactions of the Korea Information Processing Society
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• v.1 no.1
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• pp.105-113
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• 1994

This paper introduces the Parallel Advanced Loosely coupled Multiprocessor (PALM) architecture, which is based on HCH(m,p), where m is number of links per a communication processor (CP) and p is the number of application processors (APs) connected to the CP. communication links between a pair of CPs and/or between a CP and an AP, are made of dual-Port RAMs, which provide fast and reliable word-parallel communication between processors. Among the wide spectrum of HCH networks, HCH(m,2) is also known to be a cost optimal topology, such that HCH(m,2) consists of the largest number of APs retaining the minimal number of CPs and communication links. We also implement a testbed based on HCH(2,2). The experiment result shows that the small communication/computation ratio of the PALM system would realize fine-grain parallelism on message-passing MIMD systems.

• Journal of Digital Convergence
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• v.11 no.11
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• pp.421-427
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• 2013

Disk Cache Manager(DCM), a functional server of microkernel based, to improve the I/O power of shared disks is designed and implemented in this work. DCM interfaces other different servers with message passing through ports by serving as a system actor the multi-thread mode on the Minix3 micro-kernel. DCM proposed in this paper uses the shared disk logically as a Seven Disk and Sodd Disk to enable parallel I/O. DCM enables the efficient placement of disk data because it raises disk cache hit-ratio by increasing the cache size when the utilization of the particular disk is high. Through experimental results, we show that DCM is quite efficient for a shared disk with higher utilization.

• Journal of applied mathematics & informatics
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• v.11 no.1_2
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• pp.305-316
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• 2003

Recently, an iterative algorithm for finding the interior eigenvalues of a definite matrix by CG-type method has been proposed. This method compares to the inverse power method. The given matrices A, and B are assumed to be large and sparse, and SPD( Symmetric Positive Definite) The CG scheme for the optimization of the Rayleigh quotient has been proven a very attractive and promising technique for large sparse eigenproblems for smallest eigenvalue. Also, it is very amenable to parallel computations, like the CG method for the linear systems. A proper choice of the preconditioner significantly improves the convergence of the CG scheme. But for parallel computations we need to find an efficient parallel preconditioner. Our candidates we ILU(0) in the wave-front order, ILU(0) in the multi-coloring order, Point-SSOR(Symmetric Successive Overrelaxation), and Multi-Color Block SSOR preconditioner. Wavefront order is a simple way to increase parallelism in the natural order, and Multi-coloring realizes a parallelism of order(N), where N is the order of the matrix. Another choice is the Multi-Color Block SSOR(Symmetric Successive OverRelaxation) preconditioning. Block SSOR is a symmetric preconditioner which is expected to minimize the interprocessor communication due to the blocking. We implemented the results on the CRAY-T3E with 128 nodes. The MPI (Message Passing Interface) library was adopted for the interprocessor communications. The test problem was drawn from the discretizations of partial differential equations by finite difference methods. The results show that for small number of processors Multi-Color ILU(0) has the best performance, while for large number of processors Multi-Color Block SSOR performs the best.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.22 no.6
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• pp.527-532
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• 2009

In this paper simulations for the impact into ceramics and/or metal materials have been discussed. To model discrete nature for fracture and damage of brittle materials, we implemented cohesive-law fracture model with a node separation algorithm for the tensile failure and Mohr-Coulomb model for the compressive loading. The drawback of this scheme is that it requires a heavy computational time. This is because new nodes are generated continuously whenever a new crack surface is created. In order to reduce the amount of calculation, parallelization with MPI library has been implemented. For the high-speed impact problems, the mesh configuration and contact calculation changes continuously as time step advances and it causes unbalance of computational load of each processor. Dynamic load balancing technique which re-allocates the loading dynamically is used to achieve good parallel performance. Some impact problems have been simulated and the parallel performance and accuracy of the solutions are discussed.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.21 no.1
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• pp.113-124
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• 2008

Distributed operation of overall structural design process, by which product optimization and process parallelization are simultaneously implemented, is presented in this paper. The database-interacted hybrid method, which selectively takes the accustomed procedure of the conventional method in the framework of the optimal design, is utilized here. The staged application of design constraints reduces the computational burden for large complex optimization problems. Two kinds of numeric and graphic processes are simultaneously implemented by concurrent engineering approach in the distributed environment of PC networks. The former is based on finite element optimization method and the latter is represented by AutoCAD using AutoLISP programming language. Numerical computation and database interaction on servers and graphic works on independent clients are communicated through message passing. The numerical experiments for some steel truss models show the validity and usability of the method. This study has sufficient adaptability and expandability, in that it is based on general methodologies and industry standard platforms.

• The Research Journal of the Costume Culture
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• v.20 no.1
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• pp.72-82
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• 2012

The purpose of this research to look into formative characteristics of eco T-shirt design. Previous study researchers have mostly focused on overall eco fashion design, but on the other hand the research on eco product entity leaves much to be desired. We analyzed formative characteristics of eco T-shirt design that is easily accessible in real life and is easy to passing message. We selected 23 eco brands through internet and analyzed total 500 photos of eco T-shirt. Each photo was categorized by sex and the nations which belong to the eco fashion world associations. The content and statistical analysis was used for data analysis. The content of the research is as the following. First, it was found out that basic straight silhouette, achromatic color, human pattern, plant pattern, and eco-friendly organic material were used for the design of eco T-shirt. Second, it showed difference of silhouette, color, pattern according to nations. Third, it showed difference of silhouette, color, pattern according to sex. Fourth, symbolism of eco T-shirt was nature love, nature support, society ethicality, anti-sociality, and economics. This research aims for providing practical help and assistance to the development of eco T-shirt and its relevant industries.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.31 no.1
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• pp.1-7
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• 2003

The aerodynamic optimization method for airfoil design was described in this paper. The Navier-Stokes equations were solved to consider the viscous flow information around an airfoil. The Modified Method of Feasible Direction(MMFD) was used for sensitivity analysis and the polynomial interpolation was used for distance calculation of the minimization. The Message Passing Interface(MPI) library of parallel computation was adopted to reduce the computation time of flow solver by decomposing the entire computational domain into 8 sub-domains and one-to-one allocating 8 processors to 8 sub-domains. The parallel computation was also used to compute the sensitivity analysis by allocating each search direction to each processor. The present optimization reduced the drag of airfoil while the lift is maintained at the tolerable design value.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2006.05a
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• pp.99-103
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• 2006

In this paper, we focus on the problem of designing an energy efficient MAC protocol for wireless sensor networks and analyze S(Sensor)-MAC and T(Time-out)-MAC. S-MAC is based on the concept of the 'listen/sleep mode cycle'. This applies message passing to reduce contention latency for sensor-network applications that require store-and-forward processing as data moves through the network. However unlike the S-MAC, where the duration of the cycle is fixed, T-MAC introduces an adaptive duty cycle in a novel way: by dynamical ending the active part of it. This reduces the amount of energy wasted on idle listening, in which nodes wait for potentially incoming messages while still maintaining a reasonable throughput. In this paper we discuss the design of these two Protocols. We analyze them from the aspect of latency, throughput, and power savings when using the OMNeT++ simulator in various environments.

• The KIPS Transactions:PartA
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• v.10A no.3
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• pp.215-224
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• 2003

Since there are various networks and heterogeneity of nodes in Internet, the existing load-sharing algorithms are hardly adapted for use in Internet-based clustering systems. Therefore, in Internet-based clustering systems, a load-sharing algorithm must consider various conditions such as heterogeneity of nodes, characteristics of a network and imbalance of load, and so on. This paper has proposed an expanded-WF algorithm which is based on a WF (Weighted Factoring) algorithm for load-sharing in Internet-based clustering systems. The proposed algorithm uses an adaptive granularity strategy for load-sharing and duplicate execution of partial job for fault-tolerance. For the simulation, the to matrix multiplication using PVM is performed on the heterogeneous clustering environment which consists of two different networks. Compared to other algorithms such as Send, GSS and Weighted Factoring, the proposed algorithm results in an improvement of performance by 55%, 63% and 20%, respectively. Also, this paper shows that It can process the fault-tolerance.

• The KIPS Transactions:PartA
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• v.9A no.4
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• pp.563-572
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• 2002

A performance monitor is indispensable to trace and evaluate performance of a program under distributed processing environment. A performance monitor il classified as off-line and on-line according to its output method. An off-line performance monitor analyzes its performance after a program terminates, and an on-line performance monitor analyzes its one while a program runs. Therefore, the on-line function is essential to analyzing and debugging the program fast. JaNeC, distributed processing environment that is implemented in Java, contains an off-line performance monitor for this. However, this performance monitor may not analyze the program running on JaNeC efficiently. Consequently, this paper explains that an on-line performance monitor is designed and implemented for fast analysis and debugging of the program running on JaNeC. This on-line performance monitor is designed to minimize effects on a program to analyze, and provides various forms of graphic output, to analyze the program effectively. In addition, even after a program terminates, it provides interface with the off-line performance monitor, to analyze again.