• The Transactions of the Korean Institute of Electrical Engineers P
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• v.65 no.4
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• pp.335-339
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• 2016

Output power in photovoltaic systems changes steeply with the change of the sun intensity. The change of output power has influence on the electric power quality of the system. This paper proposes a residential distributed generation system using photovoltaic power generation and polymer electrolyte fuel cells(hybrid systems). In order to level the output power which changes steeply the polymer electrolyte fuel cells are connected to the photovoltaic power generation system in parallel. Thus the generated power of all the system can be leveled. However, the steep generated power in the photovoltaic power generation system can not be leveled. Therefore, the electric double layer capacitor(EDLC) is connected in parallel with the hybrid systems. It is confirmed by the simulation that the proposed distributed generation system is available for a residential supply.

• The Transactions of the Korea Information Processing Society
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• v.4 no.11
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• pp.2903-2913
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• 1997

This paper describes the design and implementation of the ParaC language that supports parallel programming on the shared memory and distributed memory parallel machine. The ParaC language is designed for the effective use of system resources of scalable parallel systems. The goal is achieved by adding parallel and synchronization constructs for shared address spaces, and remote task constructs for distributed address spaces. This paper also shows the translation method, and we implement the translator and the run-time library for parallel execution of extended constructs.

• Journal of Korea Multimedia Society
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• v.14 no.6
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• pp.835-848
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• 2011

In this paper, we propose a client server based distributed/parallel system to effectively visualize huge geographic data. The system consists of a web-based client GUI program and a distributed/parallel server program which runs on multiple PC clusters. To make the client program run on mobile devices as well as PCs, the graphical user interface has been designed by using JOGL, the java-based OpenGL graphics library, and sending the information about current available memory space and maximum display resolution the server can minimize the amount of tasks. PC clusters used to play the role of the server access requested geographic data from distributed disks, and properly re-sample them, then send the results back to the client. To minimize the latency happened in repeatedly access the distributed stored geography data, cache data structures have been maintained in both every nodes of the server and the client.

• Journal of the Korea Society for Simulation
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• v.2 no.1
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• pp.31-44
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• 1993

Zeigler's DEVS(Discrete Event Systems Specification) formalism supports formal specification of discrete event systems in a hierarchical , modular manner. Associated are hierarchical, distributed simulation algorithms, called abstract simulators, which interpret dynamics of DEVS models. This paper deals with performance evaluation of P-DEVSIM ++, a parallel simulation environment which implements the DEVS formalism and associated simulation algorithms in a parallel environment. Performance simulator has been developed and used to experiment models of parallel simulation executions in different conditions. The experimental result shows that simulation time depends on both the number of processors in the parallel system and the communication overheads among such processors.

• Journal of the Korean Society for Precision Engineering
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• v.22 no.1
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• pp.122-129
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• 2005

On the cluster system, the parallel code of rigid-plastic FEM has been developed. The cluster system, Simforge, has 15 processors and the total memory is 4.5GBytes. In the developed parallel code, the distributed data of the column-wise partitioned stiffness are stored as the compressed row storage and the diagonal preconditioned conjugate gradient solver is applied. The analysis of block upsetting is performed with the parallel code on Simforge cluster system. In this paper, the analysis results are compared and discussed.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2001.04a
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• pp.61-68
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• 2001

A parallel nonlinear analysis program of prestressed concrete frame is migrated on a PC cluster system and a massively parallel processing system, CRAY T3E system, using MPI. The PC cluster system is configured with Pentium Ⅲ class PCs and fast ethernet. The CRAY T3E system is composed of a set of nodes each containing one Processing Element (PE), a memory subsystem and its distributed memory interconnect network. Parallel computing algorithms are implemented on element-wise processing parts including the calculation of stiffness matrix, element stresses and determination of material states, check of material failure and calculation of unbalanced loads. Parallel performance of the migrated program is evaluated through typical numerical examples.

• Proceedings of the Korea Inteligent Information System Society Conference
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• 2001.01a
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• pp.111-115
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• 2001

In this paper, a simple and systematic control design method is proposed for a discrete-time Takagi-Sugeno(TS) fuzzy system, which employs the parallel distributed compensation(PDC) to determine the structure of a fuzzy controller so as to mark all the Lyaunov exponents of the controlled TS fuzzy system strictly positive. This approach is proven to be mathematically rigorous for anticontrol of chaos for a TS fuzzy system in the sense that any given discrete-time TS fuzzy system can be made chaotic by the designed PDC controller along with the-operation. A numerical example is included to visualize the anticontrol effect.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2004.04a
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• pp.389-395
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• 2004

We consider the interface between the parallel distributed memory multifrontal solver and the finite element method. We give in detail the requirement and the data structure of parallel FEM interface which includes the element data and the node array. The full procedures of solving a large scale structural problem are assumed to have pre-post processors, of which algorithm is not considered in this paper. The main advantage of implementing the parallel FEM interface is shown up in the case that we use a distributed memory system with a large number of processors to solve a very large scale problem. The memory efficiency and the performance effect are examined by analyzing some examples on the Pegasus cluster system.

• Journal of Communications and Networks
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• v.18 no.2
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• pp.218-226
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• 2016

Coordination among users is an inevitable but time-consuming operation in wireless networks. It severely limit the system performance when the data rate is high. We present FC-MAC, a novel MAC protocol that can complete a contention within one contention slot over a joint frequency-code domain. When a node takes part in the contention, it generates randomly a contention vector (CV), which is a binary sequence of length equal to the number of available orthogonal frequency division multiplexing (OFDM) subcarriers. In FC-MAC, different user is assigned with a distinct signature (i.e., PN sequence). A node sends the signature at specific subcarriers and uses the sequence of the ON/OFF states of all subcarriers to indicate the chosen CV. Meanwhile, every node uses the redundant antennas to detect the CVs of other nodes. The node with the minimum CV becomes the winner. The experimental results show that, the collision probability of FC-MAC is as low as 0.05% when the network has 100 nodes. In comparison with IEEE 802.11, contention time is reduced by 50-80% and the throughput gain is up to 200%.

• Proceedings of the KIEE Conference
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• 2004.07d
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• pp.2215-2217
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• 2004

In this paper, a systematic design approach based on the parallel distributed compensation technique is proposed for chaotifying a general continuous-time Takagi-Sugeno (TS) fuzzy system. The fuzzy parallel distributed compensation controller (FPDCC) is composed of the feedback gain and time-delay feedback. The verification of chaos in the controlled continuous-time TS fuzzy system is done by the following procedures. First, we establish an asymptotically approximate relationship between a time-delay continuous-time TS fuzzy system and a discrete-time TS fuzzy system. Then, Marotto theorem is applied. Therefore, the generated chaos is in the sense of Li and Yorke. The boundedness in the controlled continuous-time TS fuzzy system is also proven via its associated discrete-time TS fuzzy system.