• Journal of Digital Convergence
• /
• v.11 no.11
• /
• pp.421-427
• /
• 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 Convergence for Information Technology
• /
• v.10 no.1
• /
• pp.22-27
• /
• 2020

With the deployment of 5G infrastructure, content delivery network (CDN) will be a key role to provide explosive growing services for the independent media and YouTube which contain high-speed mobile contents. Without a local cache, the mobile backhaul and fronthaul should endure huge burden of bandwidth request for users as the increase number of direct accesses from contents providers. To deal with this issue, this paper fist presents both fronthaul solutions for CDN that use dark fibers and a passive optical network (PON). On top of that, we propose the aggregated content request specialized for PON caching and evaluate and compare its performance to legacy schemes through the simulation. The proposed PON caching scheme can reduce average access time of up to 0.5 seconds, 1/n received request packets, and save 60% of backhaul bandwidth compared to the no caching scheme. This work can be a useful reference for service providers and will be extended to further improve the hit ratio of cache in the future.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.9 no.8
• /
• pp.1847-1854
• /
• 2005

This paper proposes a approach to configure efficient video-on-demand system by introducing Multicast and Cache Video-on-Demand (MCVoD) system. As a key element or the MCVoD system, interchange agent provides this system with multicasting and switching functions. With the multicasting, the MCVoD system is able to reduce the load on the network as well as VoD servers by transmitting only one video request instead of sending multiple requests on a same video stream. The switching enables clients to receive the lust stream of requested video streams instantly without waiting time and also allows avoiding undesirable duplication of video streams in the system. With various experiment results through simulation about waiting tine and cache hit ratio, we show that the MCVoD system employing the interchange agent provides better performance than current uni-proxy based system.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.41 no.2
• /
• pp.178-188
• /
• 2016

The traffic in the wired and wireless networks has increased exponentially because of increase of smart phone and improvement of PC performance. Multimedia services and file transmission such as Facebook, Youtube occupy a large part of the traffic. CDN is a technique that duplicates the contents on a remote web server of content provider to local CDN servers near clients and chooses the optimal CDN server for providing the content to the client in the event of a content request. In this paper, the content request message between CDN servers and the client used the SCRP algorithm utilizing the MST algorithm and the traffic throughput was optimized. The average response time for the content request is reduced by employing HC_LRU cache algorithm that improves the cache hit ratio. The proposed SCRP and HC_LRU algorithm may build a scalable content delivery network system that efficiently utilizes network resources, achieves traffic localization and prevents bottlenecks.

• Journal of KIISE:Computer Systems and Theory
• /
• v.37 no.5
• /
• pp.285-291
• /
• 2010

Flash memory has many good features such as small size, shock-resistance, and low power consumption, but the cost of flash memory is still high to substitute for hard disk entirely. Recently, some mobile devices, such as laptops, attempt to use both flash memory and hard disk together for taking advantages of merits of them. However, existing OSs (Operating Systems) are not optimized to use the heterogeneous storage media. This paper presents a new buffer cache management scheme. First, we allocate buffer cache space according to access patterns of block references and the characteristics of storage media. Second, we prefetch data blocks selectively according to the location of them and access patterns of them. Third, we moves destaged data from buffer cache to hard disk or flash memory considering the access patterns of block references. Trace-driven simulation shows that the proposed schemes enhance the buffer cache hit ratio by up to 29.9% and reduce the total I/O elapsed time by up to 49.5%.

• Proceedings of the Korea Inteligent Information System Society Conference
• /
• 2005.11a
• /
• pp.241-250
• /
• 2005

New product development (NPD) is defined as the transformation of a market opportunity and a set of assumptions about product technology into a product available for sale. Managers charged with project selection decisions in the NPD process, such as go/no-go choices and specific resource allocation decisions, are faced with a complicated problem. Therefore, the ability to develop new successful products has identifies as a major determinant in sustaining a firm's competitive advantage. The purpose of this study is to develop a new evaluation model for NPD project selection in the high -tech industry using support vector machines (SYM). The evaluation model is developed through two phases. In the first phase, binary (go/no-go) classification prediction model, i.e. SVM for high-tech NPD project selection is developed. In the second phase. using the predicted output value of SVM, feasibility grade is calculated for the final NPD project decision making. In this study, the feasibility grades are also divided as three level grades. We assume that the frequency of NPD project cases is symmetrically determined according to the feasibility grades and misclassification errors are partially minimized by the multiple grades. However, the horizon of grade level can be changed by firms' NPD strategy. Our proposed feasibility grade method is more reasonable in NPD decision problems by considering particularly risk factor of NPD in viewpoints of future NPD success probability. In our empirical study using Korean NPD cases, the SVM significantly outperformed ANN and logistic regression as benchmark models in hit ratio. And the feasibility grades generated from the predicted output value of SVM showed that they can offer a useful guideline for NPD project selection.

• Journal of Korea Multimedia Society
• /
• v.7 no.5
• /
• pp.668-679
• /
• 2004

When users of mobile environments move fast or slow into a number of base stations(BS) and request the services of continuous media data such as video or audio, this study examines what the caching has the usefulness in mobile environments. Namely, to reduce packet disconnections and network overheads in mobile environments and minimize transmission delay time, we propose domain-based hierarchical caching structure and study whether application of caching has the usefulness. So we have a model based on user environments and hierarchical network structure to process continuous media services, and analyze the usefulness of caching which depends on the mobile patterns of user and the locations of caching nodes. And then, we research whether caching offers the usefulness in mobile environments. As the result, we are able to see that an adaptable application of caching is needed because the hit ratio and the number of replacement vary in large according to mobile patterns of user and locations of caching.

• Journal of KIISE:Software and Applications
• /
• v.29 no.7
• /
• pp.487-497
• /
• 2002

As component-based reuse technology is being introduced, software components are more likely distributed on Internet. In order to promote Internet based on-line distribution, distribution model of components should be defined and a distribution system should also be constructed. Furthermore, to run the component distribution system effectively, a logical and practical schema for classifying components should be defined and standardized. In this paper, we propose a classification schema using BNF and representation standards of components using six different views. To verity the effectiveness of proposed classification and compare to other classification methods, we assess proposed classification by measuring hit ratio and correctness. By using the proposed methods that support six views on components, the search for right components and registering new components can be done more effectively.

• Journal of Korean Society on Water Environment
• /
• v.34 no.6
• /
• pp.602-620
• /
• 2018

Korean benthic macroinvertebrate community from 959 sites and 14 environmental factors that could affect the biological distribution were surveyed and analyzed. The 438 taxa were divided into six groups according to TWINSPAN. Based on the environmental factor values corresponding to each taxon, the average and range of environmental factors for each biological group tended to increase or decrease in eight environmental factors (altitude, slope, current velocity, fraction of fine particles in substrates, turbidity, $BOD_5$, T-N and T-P). As a result of discriminant analysis (hit ratio: 69.6 %), environmental factors that significantly influence the distribution of each biological group were $BOD_5$, altitude, catchment area, T-N, T-P and fraction of fine particles in substrates. The discriminant functions 1 and 2 classified the existing six biological groups (clustered by TWINSPAN) into five (group 1: highland highly sensitive group; group 2: lowland sensitive group, group; 3 and 4: lowland slightly tolerant group; group 5: lowland tolerant group; group 6: lowland highly tolerant group). Most of the benthic macroinvertebrates were identified in the species level. However, a few others were identified in genus or family level, too. Even the organisms belonging to the same genus or family may prefer different environmental factors in the species level, the identification of characteristic of the habitat environment preferred by organism and species level identification of these organisms are utmost. The results of this study may be used as basic information on environmental factors which can be considered in preservation and restoration research for biodiversity.

• Journal of the Korea Convergence Society
• /
• v.12 no.6
• /
• pp.173-181
• /
• 2021

In previous research, large companies were analyzed to focus on their past management performance and patent rights, but in this study we looked at the variability in future sales of small and medium-sized enterprises with patents through empirical analysis. We looked at how the quantitative and qualitative value of patent rights affect management performance of company. We used 'the number of patents' as the quantitative value of patents, 'the average score of patents' as the qualitative value of patents, and the average sales growth rate as the management performance of company. Through a discriminant analysis using the statistical program SPSS, both independent variables used in this study were significant for distinguishing between companies with an average growth in sales more than twice that of general small and medium-sized enterprises and those with less than twice the average sales growth rate. Therefore it is meaningful to provide stakeholders with an analysis framework on how sales will change in the future using the results of this study during guarantee or loan screening for small and medium-sized enterprises with patent rights.