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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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The KIPS Transactions:PartA
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Korea Information Processing Society
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Volume & Issues
Volume 14A, Issue 7 - Dec 2007
Volume 14A, Issue 6 - Dec 2007
Volume 14A, Issue 5 - Oct 2007
Volume 14A, Issue 4 - Aug 2007
Volume 14A, Issue 3 - Jun 2007
Volume 14A, Issue 2 - Apr 2007
Volume 14A, Issue 1 - Feb 2007
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MPICH-GP : An MPI Extension to Supporting Private IP Clusters in Grid Environments
Park, Kum-Rye ; Yun, Hyun-Jun ; Park, Sung-Yong ; Kwon, Oh-Young ; Kwon, Oh-Kyoung ;
The KIPS Transactions:PartA, volume 14A, issue 1, 2007, Pages 1~14
DOI : 10.3745/KIPSTA.2007.14-A.1.001
MPICH-G2 is an MPI implementation to solve complex computational problems by utilizing geographically dispersed computing resources in grid environments. However, the computation nodes in MPICH-G2 are exposed to the external network due to the lack of supporting the private IP clusters, which raises the possibility of malicious security attacks. In order to address this problem, we propose MPICH-GP with a new relay scheme combining NAT(Network Address Translation) service and an user-level proxy. The proxy running on the front-end system of private IP clusters forwards the incoming connection requests to the systems inside the clusters. The outgoing connection requests out of the cluster are forwarded through the NAT service on the front-end system. Through the connection path between the pair of processes, the requested MPI jobs can be successfully executed in grid environments with various clusters including private IP clusters. By simulations, we show that the performance of MPICH-GP reaches over 80% of the performance of MPICH-G2, and over 95% in ease of using RANK management method.
MediaFrame: Parallel multimedia system architecture through HTTP redirection
Kim, Seong-Ki ; Han, Sang-Yong ;
The KIPS Transactions:PartA, volume 14A, issue 1, 2007, Pages 15~24
DOI : 10.3745/KIPSTA.2007.14-A.1.015
As a single video server exposes its limitation in scalability, capability, fault-tolerance, and cost-efficiency, solutions of this limitation emerge. However, these solutions have their own problems that will be discussed in this paper. To solve these problems and exploit various video silvers, we designed a parallel multimedia system architecture that supported a content-aware routing to heterogeneous personal computer (PC), operating system (OS), video servers through a HTTP-level redirection. We also developed a prototype, added different video servers into the prototype, and measured its overheads.
Policy Factors in the Development of IT Assistive Devices: A Comparative Study between Korea and America
Cho, Joo-Eun ;
The KIPS Transactions:PartA, volume 14A, issue 1, 2007, Pages 25~30
DOI : 10.3745/KIPSTA.2007.14-A.1.025
Korea has deeper digital divide between disabled and non-disabled people than other industrialized countries have. This study attributes the deep divide to policy factors and attempts to discern differences in policies concerning IT assistive devices between Korea and America. This study finds that major differences in policy exist between the two countries, and the differences account for Korea's unsatisfactory state of digital divide. Firstly, Korra has different 'perception' of assistive devices. While IT assistive devices are perceived as rehabilitation tools as well as bridges over digital divide in America, they are still foreign to social welfare and rehabilitation of disabled people in Korea. Secondly, the two countries differ in 'enforcement of policy.' In Korea, unlike in America, compliance with regulations on assistive devises is not compulsory. Besides, laws and regulations do not clarify possible sources of financing and legal sanctions, thus their enforcement is hardly effective. Thirdly, Korea's strategy for assistive device 'market' is very different from America's. America has long-term strategies to enliven the market for IT assistive devices. But Korea provided a lump sum of device development fund, and then gave out the assistive devices free of charge. As a result, the IT assistive device market has not been formed, and the foundation for further device development is yet to be constructed.
Automatic Generation of Code Optimizer for DFA Pattern Matching
Yun, Sung-Lim ; Oh, Se-Man ;
The KIPS Transactions:PartA, volume 14A, issue 1, 2007, Pages 31~38
DOI : 10.3745/KIPSTA.2007.14-A.1.031
Code Optimization is converting to a code that is equivalent to given program but more efficient, and this process is processed in Code Optimizer. This paper designed and processed Code Optimizer Generator that automatically generates Code Optimizer. In other words Code Optimizer is automatically generated for DFA Pattern Matching which finds the optimal code for the incoming pattern description. DFA Pattern Matching removes redundancy comparisons that occur when patterns are sought for through normalization process and improves simplification and structure of pattern shapes for low cost. Automatic generation of Code Optimization for DFA Pattern Matching eliminates extra effort to generate Code Optimizer every time the code undergoes various transformations, and enables formalism of Code Optimization. Also, the advantage of making DFA for optimization is that it is faster and saves cost of Code Optimizer Generator.
A garbage collector design and implementation for flash memory file system
Kim, Ki-Young ; Son, Sung-Hoon ; Shin, Dong-Ha ;
The KIPS Transactions:PartA, volume 14A, issue 1, 2007, Pages 39~46
DOI : 10.3745/KIPSTA.2007.14-A.1.039
Recently flash memory is widely accepted as a storage devise of embedded systems for portability and performance reasons. Flash memory has many distinguishing features compared to legacy magnetic disks. Especially, a file system for flash memory usually assumes the form of log-structured file system and it employs garbage collector accordingly. Since the garbage collector can greatly affect the performance of file system, it should be designed carefully considering flash memory features. In this paper, we suggest a new garbage collector for existing JFFS2 (Journaling Flash File System II) file system. By extensive performance evaluation, we show that the proposed garbage collector achieves improved performance in terms of flash memory consumption rate, increased flash memory life time, and improved wear-leveling.
Low Power TLB System by Using Continuous Accessing Distinction Algorithm
Lee, Jung-Hoon ;
The KIPS Transactions:PartA, volume 14A, issue 1, 2007, Pages 47~54
DOI : 10.3745/KIPSTA.2007.14-A.1.047
In this paper we present a translation lookaside buffer (TLB) system with low power consumption for imbedded processors. The proposed TLB is constructed as multiple banks, each with an associated block buffer and a corresponding comparator. Either the block buffer or the main bank is selectively accessed on the basis of two bits in the block buffer (tag buffer). Dynamic power savings are achieved by reducing the number of entries accessed in parallel, as a result of using the tag buffer as a filtering mechanism. The performance overhead of the proposed TLB is negligible compared with other hierarchical TLB structures. For example, the two-cycle overhead of the proposed TLB is only about 1%, as compared with 5% overhead for a filter (micro)-TLB and 14% overhead for a same structure without continuos accessing distinction algorithm. We show that the average hit ratios of the block buffers and the main banks of the proposed TLB are 95% and 5% respectively. Dynamic power is reduced by about 95% with respect to with a fully associative TLB, 90% with respect to a filter-TLB, and 40% relative to a same structure without continuos accessing distinction algorithm.
An Energy Efficient and High Performance Data Cache Structure Utilizing Tag History of Cache Addresses
Moon, Hyun-Ju ; Jee, Sung-Hyun ;
The KIPS Transactions:PartA, volume 14A, issue 1, 2007, Pages 55~62
DOI : 10.3745/KIPSTA.2007.14-A.1.055
Uptime of embedded processors for mobile devices are dependent on battery consumption. Especially the large portion of power consumption is known to be due to cache management in embedded processors. This paper proposes an energy efficient data cache structure for high performance embedded processors. High performance prefetching data cache issues prefetching instructions before issuing demand-fetch instructions based on reference predictions. These prefetching instruction bring reduction on memory delay by improving cache hit ratio, but on the other hand those increase energy consumption in proportion to the number of prefetching instructions. In this paper, we adopt tag history table on prefetching data cache for reducing energy consumption by minimizing parallel tag comparison. Experimental results show the proposed data cache improves performance on energy consumption as well as memory delay.
Request Distribution for Fairness with a Non-Periodic Load-Update Mechanism for Cyber Foraging Dynamic Applications in Web Server Cluster
Lu, Xiaoyi ; Fu, Zhen ; Choi, Won-Il ; Kang, Jung-Hun ; Ok, Min-Hwan ; Park, Myong-Soon ;
The KIPS Transactions:PartA, volume 14A, issue 1, 2007, Pages 63~72
DOI : 10.3745/KIPSTA.2007.14-A.1.063
This paper introduces a load-balancing algorithm focusing on distributing web requests evenly into the web cluster servers. The load-balancing algorithms based on conventional periodic load-information update mechanism are not suitable for dynamic page applications, which are common in Cyber Foraging services, due to the problems caused by periodic synchronized load-information updating and the difficulties of work load estimation caused by embedded executing scripts of dynamic pages. Update-on-Finish algorithm solves this problem by using non-periodic load-update mechanism, and the web switch knows the servers' real load information only after their reporting and then distributes new loads according to the new load-information table, however it results in much communication overhead. Our proposed mechanism improve update-on-finish algorithm by using K-Percents-Finish mechanism and thus largely reduce the communication overhead. Furthermore, we consider the different capabilities of servers with a threshold Ti value and propose a load-balancing algorithm for servers with various capabilities. Simulation results show that the proposed K-Percents-Finish Reporting mechanism can at least reduce 50% communication overhead than update-on-finish approach while sustaining better load balancing performance than periodic mechanisms in related work.
A study on the Automatic Algorithm for Numerical Conformal Mapping
Song, Eun-Jee ;
The KIPS Transactions:PartA, volume 14A, issue 1, 2007, Pages 73~76
DOI : 10.3745/KIPSTA.2007.14-A.1.073
The determination of the conformal maps from the unit disk onto a Jordan region has been completed by solving the Theodorsen equation which is an nonlinear equation for the boundary correspondence function. Wegmann's method has been well known for the efficient mothed among the many suggestions for the Theodorsen equation. We proposed an improved method for convergence by applying a low-frequency pass filter to the Wegmann's method and theoretically proved convergence of improved iteration[1, 2]. And we proposed an effective method which makes it possible to estimate an error even if the real value is nut acquired. In this paper, we propose an automatic algorithm for numerical conformal mapping bared on this error analysis in our early study. By this algorithm numerical conformal mapping is determined automatically according to the given domain of problem and the required accuracy. The discrete numbers and parameters of the low-frequency filter were acquired only by experience. This algorithm, however, is able to determine the discrete numbers and parameters of the low-frequency filter automatically in accordance with the given region This results from analyzing the function, which may decide the shape of the given domain under the assumption that the degree of the problem depends of the transformation of a given domain, as seen in the Fourier Transform. This proposed algorithm is also ploved by numerical experience.