• Journal of Convergence for Information Technology
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• v.8 no.6
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• pp.237-242
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• 2018

There are various 'wireless communication technologies' around us. Wireless mobile communication has evolved through various stages, and its utilization is also diverse. However, due to the development of wireless communication technology, the demand for frequency resources is much higher than the supply, so frequency shortage is serious. Recently, 'visible light communication' has been attracting attention as an emerging communication technology that can solve the frequency shortage. 'Visible light communication' is a communication method based on serial data transmission / reception, and there is a difficulty in transmitting / receiving parallel data because the transmitter and the receiver are arbitrarily present. In this paper, we have studied parallel data processing of visible light communication. We could solve the problem by analyzing parallel data using image processing. Through this study, communication performance can be verified through I / O data comparison by implementing parallel data analysis method. It is expected that diversity in parallel data analysis will be presented through the results.

• Journal of the Korea Society of Computer and Information
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• v.27 no.2
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• pp.1-8
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• 2022

In this paper, we design and implement a GPU-based parallel algorithm to effectively solve the traveling salesman problem through an ant color system. The repetition process of generating hundreds or thousands of tours simultaneously in TSP utilizes GPU's task-level parallelism, and the update process of pheromone trails data actively exploits data parallelism by 32x32 thread blocks. In particular, through simultaneous memory access of multiple threads, the coalesced accesses on continuous memory addresses and concurrent accesses on shared memory are supported. This experiment used 127 to 1002 city data provided by TSPLIB, and compared the performance of sequential and parallel algorithms by using Intel Core i9-9900K CPU and Nvidia Titan RTX system. Performance improvement by GPU parallelization shows speedup of about 10.13 to 11.37 times.

• Journal of the Korean Institute of Intelligent Systems
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• v.10 no.5
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• pp.409-416
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• 2000

In the shared-memory mutiprocessor systems, shared processing techniques such as time-sharing, space¬sharing, and gang-scheduling are used to improve the overall system utilization for the parallel operations. Recently, LLPC(Loop-Level Process Control) allocation technique was proposed. It dynamically adjusts the needed number of processors for the execution of the parallel code portions based on the current system load in the given job. This method allocates as many available processors as possible, and does not save any processors for the parallel sections of other later-arriving applications. To solve this problem, in this paper, we propose a new processor allocation technique called FPA(Fuzzy Processor Allocation) that dynamically adjusts the number of processors by fuzzifYing the amounts ofueeded number of processors, loads, and estimated execution times of job. The proposed method provides the maximum possibility of the parallism of each job without system overload. We compare the performances of our approaches with the conventional results. The experiments show that the proposed method provides a better performance.

• The KIPS Transactions:PartC
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• v.8C no.6
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• pp.765-774
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• 2001

In this paper, we proposed the striping policy for the storage nodes in the Linux-based parallel media stream server. We newly developed a storage clustering architecture, and named it as a system RAID architecture. In this system, many storage cluster nodes are grouped to operate as a single server. This system uses unique striping policy to distribute multimedia files into the parallel storage nodes. If a service request occurs, each storage cluster node transmits striped files concurrently to the clients. This scheme can provide the fair distribution of the preprocessing load in all storage cluster nodes. The feature of this system is a relative striping policy based on the file types, service types, and the number of storage nodes to provide the best service.

• Journal of KIISE:Computer Systems and Theory
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• v.26 no.7
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• pp.752-765
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• 1999

대부분 병렬처리 시스템에서 성능 파라미터는 복잡하고 프로그램의 수행 시 예견할 수 없게 변하기 때문에 컴파일러가 프로그램 수행에 대한 최적의 성능 파라미터들을 컴파일 시에 결정하기가 힘들다. 본 논문은 병렬 처리 시스템의 프로그램 수행 시, 변화하는 시스템 성능 상태에 따라 전체 성능이 최적화로 적응하는 적응 수행 방식을 제안한다. 본 논문에서는 이 적응 수행 방식 중에 적응 프로그램 수행을 위한 이론적인 방법론 및 구현 방법에 대해 제안하고 적응 제어 수행을 위해 프로그램의 데이타 공유 단위에 대한 적응방식(적응 입도 방식)을 사용한다. 적응 프로그램 수행 방식은 프로그램 수행 시 하드웨어와 컴파일러의 도움으로 프로그램 자신이 최적의 성능을 얻을 수 있도록 적응하는 방식이다. 적응 제어 수행을 위해 수행 시에 병렬 분산 공유 메모리 시스템에서 프로세서 간 공유될 수 있은 데이타의 공유 상태에 따라 공유 데이타의 크기를 변화시키는 적응 입도 방식을 적용했다. 적응 입도 방식은 기존의 공유 메모리 시스템의 공유 데이타 단위의 통신 방식에 대단위 데이타의 전송 방식을 사용자의 입장에 투명하게 통합한 방식이다. 시뮬레이션 결과에 의하면 적응 입도 방식에 의해서 하드웨어 분산 공유 메모리 시스템보다 43%까지 성능이 개선되었다. Abstract On parallel machines, in which performance parameters change dynamically in complex and unpredictable ways, it is difficult for compilers to predict the optimal values of the parameters at compile time. Furthermore, these optimal values may change as the program executes. This paper addresses this problem by proposing adaptive execution that makes the program or control execution adapt in response to changes in machine conditions. Adaptive program execution makes it possible for programs to adapt themselves through the collaboration of the hardware and the compiler. For adaptive control execution, we applied the adaptive scheme to the granularity of sharing adaptive granularity. Adaptive granularity is a communication scheme that effectively and transparently integrates bulk transfer into the shared memory paradigm, with a varying granularity depending on the sharing behavior. Simulation results show that adaptive granularity improves performance up to 43% over the hardware implementation of distributed shared memory systems.

• KIPS Transactions on Computer and Communication Systems
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• v.12 no.7
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• pp.209-216
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• 2023

Modern HPC systems are equipped with many-core CPUs with dozens of cores. When performing parallel I/O in such a system, there is a limit to scalability due to the problem of the LRU lock management policy of the Linux system. The study proposes an improved FinerLRU to solve this problem. Our new FinerLRU improves the parallel write performance of file systems using the buffer cache through granular lock management by increasing the number of LRU locks upto the maximum number of cores. The proposed method was implemented in Linux 5.18.11, and the performance was measured on two types of CPUs, Intel Icelake Xeon and Intel Knights landing, with different characteristics, and it was found that a performance improvement of about two times can be obtained in both types of systems.

• The Journal of the Acoustical Society of Korea
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• v.18 no.1
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• pp.3-9
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• 1999

This paper concerns performance of a parallel digital signal processing system. The performance of the system is analyzed in terms of CPU cycles required for 1024-point FFT computation. The number of cycles is estimated in three different approaches; FFT algorithm-based, assembly level source code-based, and probability-based. The results of analysis indicate that on a bus-based system the best performance for FFT is achieved with a single board. Because in some applications like FFT, where frequent data exchanges among processors occur, the number of communication cycles increases as the number of boards. It is observed that inter-board communication degrades overall system performance for the FFT computation. Also shown is that linear increase in performance can be obtained if multiple buses are employed.

• Proceedings of the Korea Contents Association Conference
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• 2007.11a
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• pp.547-549
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• 2007

Recently with increasing the use of parallel computing and cluster system which was connected high speed network, the interest about distributed and parallel file system is increasing. Specially, there are many researches, which focused on optimizing the performance of distributed and parallel file system for the more efficient use of cluster system. In this paper, we analyzed the performance of PVFS(Parallel Virtual File System) in small cluster system. In addition, to improve the PVFS performance we proposed the chancing the size of flow buffer according to the network speed and we optimized the PVFS performance on small cluster system.

• Proceedings of the KIEE Conference
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• 2007.04c
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• pp.223-226
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• 2007

본 연구에서는 Z-소스 네트워크를 갖는 능동전력필터 시스템을 제안하였다. 제안된 방식의 동작원리는 종전의 V-소스 능동전력필터와 동일하나, 고조파 보상 전류가 Z-소스 인버터에 의하여 발생된다는 점이 차이가 있다. 또 제안된 시스템을 서로 병렬 운전하는 경우와 종전의 능동전력필터와 병렬 운전하는 방법을 제안하였다. 제안된 시스템은 PSIM 시뮬레이션에 의하여 타당성이 입증되었다.

• Proceedings of the Korean Information Science Society Conference
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• 2003.04a
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• pp.97-99
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• 2003

대칭형 다중프로세서 (SMP: Symmetric Multiprocessors) 시스템은 고성능의 병렬 연산을 위한 중요하고 효과적인 기반환경을 제공하고 있다. SMP에서 태스크 클러스터링과 스케줄링 기법은 시스템의 성능에 큰 영향을 미친다. 본 논문에서는 버스 기반의 SMP에서 사용할 수 있는 태스크 중복 기반의 클러스터링과 스케줄링 기법을 소개한다. 본 논문에서 제안한 클러스터링 기법에서는 휴리스틱을 사용하여 중복할 태스크를 선택한 후 프로세서에 할당하고, 스케줄링 기법에서는 잠재하는 통신 충돌을 방지하기 위하여 네트워크 통신 자원을 사전에 할당한다. 새로운 클러스터링과 스케줄링 기법의 성능을 확인하기 위하여 시뮬레이션에서는 통신비용의 변화에 대한 병렬연산시간을 비교하였다.