• Journal of KIISE
• /
• v.42 no.8
• /
• pp.972-978
• /
• 2015

Non-volatile memory (NVM) supports both byte addressability and non-volatility. These characteristics make it feasible for NVM to be employed at any layer of the memory hierarchy such as cache, memory and disk. An interesting characteristic of NVM is that, even though it supports non-volatility, its retention capability is limited. Furthermore NVM has tradeoff between its retention capability and write latency. In this paper, we propose a novel NVM-based file cache management scheme that makes use of the limited retention capability to improve the cache performance. Experimental results with real-workloads show that our scheme can reduce access latency by up to 31% (24.4% average) compared with the conventional LRU based cache management scheme.

• Journal of Korea Multimedia Society
• /
• v.5 no.1
• /
• pp.47-56
• /
• 2002

Previous buffer cache schemes for multimedia storage systems only exploited the sequential references of multimedia files and didn't consider looping references. However, in some video applications like foreign language learning, users mark the scene as loop area and then application automatically playbacks the scene several times. In this paper, we propose a new buffer replacement scheme, called HBM(Hybrid Buffer Management), for multimedia storage systems that have both sequential and looping references. Proposed scheme assumes that application layer informs reference pattern of files to file system. Then HBM applies an appropriate replacement policy to each file. Our simulation experiments show that HBM outperforms previous buffer cache schemes such as DISTANCE and LRU.

• Journal of the Institute of Electronics and Information Engineers
• /
• v.50 no.4
• /
• pp.117-123
• /
• 2013

In the recent cloud storage environment, the amount of SSD (Solid-State Drive) replacing with the traditional hard disk drive is increasing. Management of SSD for its space efficiency has become important since SSD provides fast IO performance due to no mechanical movement whereas it has wearable characteristics and does not provide in place update. In order to manage space efficiency of SSD, data de-duplication technique is frequently used. However, this technique occurs much overhead because it consists of data chunking, hasing and hash matching operations. In this paper, we propose new data de-duplication method using PRAM cache. The proposed method uses hierarchical hash tables and LRU(Least Recently Used) for data replacement in PRAM. First hash table in DRAM is used to store hash values of data cached in the PRAM and second hash table in PRAM is used to store hash values of data in SSD storage. The method also enhance data reliability against power failure by maintaining backup of first hash table into PRAM. Experimental results show that average writing frequency and operation time of the proposed method are 44.2% and 38.8% less than those of existing data de-depulication method, respectively, when three workloads are used.

• Journal of KIISE:Computing Practices and Letters
• /
• v.16 no.1
• /
• pp.1-10
• /
• 2010

Recently heterogeneous storage system such as hybrid hard disk drive (H-HDD) combining flash memory and magnetic disk is launched, according as the read performance of NAND flash memory is enhanced as similar to that of hard disk drive (HDD) and the power consumption of NAND flash memory is reduced less than that of HDD. However, the read and write operations of NAND flash memory are slower than those of rotational disk. Besides, serious overheads are incurred on CPU and main memory in the case that intensive write requests to flash memory are repeatedly occurred. In this paper, we propose the Least Frequently Used-Hot scheme that replaces the data blocks whose reference frequency of read operation is low and update frequency of write operation is high, and the data flushing scheme that rearranges the data blocks into the multi-zone of the rotation disk. Experimental results show that the execution time of the proposed method is 38% faster than those of conventional LRU and LFU block replacement schemes in I/O performance aspect and the proposed method increases the life span of Non-Volatile Cache 40% higher than those of conventional LRU, LFU, FIFO block replacement schemes.

• International Journal of Contents
• /
• v.3 no.1
• /
• pp.14-18
• /
• 2007

General replacement policy includes document-based LRU or LFU technique and other various replacement policies are used to replace the documents within cache effectively. But, these replacement policies function only with regard to the time and frequency of document request, not considering the popularity of each web site. In this paper, we present the document replacement policies with regard to the popularity of each web site, which are suitable for modern network environments to enhance the hit-ratio and efficiently manage the contents of cache by effectively replacing documents on intermittent requests by new ones.

• 한국정보디스플레이학회:학술대회논문집
• /
• 2008.10a
• /
• pp.488-491
• /
• 2008

The variations of the TFT characteristics in AMOLEDs result in the decrease of the uniformity of the displays. Measurement of the long-range uniformity (LRU) is straightforward. However, there is no method for measuring the short-range uniformity (SRU) yet. Quantifying the SRU is important in evaluating various TFT backplanes and compensation circuits. We propose new methods for measuring SRU.

• Proceedings of the KSR Conference
• /
• 2007.05a
• /
• pp.255-261
• /
• 2007

In this paper we introduce the method, procedure and result of RAM prediction for interlocking system which is applied for AREX signaling system. For RAM prediction, we breakdown the interlocking system to the LRU level and select the LRUs of which failure can cause the service delay. The prediction of reliability is based on the Reliability Block Diagram which is the functional diagram composed of selected LRUs and finally, the availability of interlocking system is estimated from the combination of reliability and maintainability.

• Proceedings of the Korea Information Processing Society Conference
• /
• 2005.05a
• /
• pp.1757-1760
• /
• 2005

요구 페이징 방식의 가상메모리 시스템에서 페이지 참조 스트링에 따른 페이지 교체 알고리즘의 성능평가를 위한 시뮬레이션을 개발한다. 참조 집약성을 기반으로 워킹세트(working set) 모델을 수정한 MWS 교체 알고리즘을 제안하였고 다양한 교체 알고리즘(FIFO, SC, LFU, LRU, Rand)들과 비교 실험한 결과 MWS는 발생 페이지 부재 수 측면에서 다른 교체 정책 보다 성능이 우수하였다.

• Proceedings of the Korean Information Science Society Conference
• /
• 2000.04a
• /
• pp.12-14
• /
• 2000

소형의 이동 컴퓨터 시스템이 발전하면서 프로세서의 전력 소모(energy dissipation)가 중요한 이슈가 되고 있다. 현재 대부분의 프로세서들은 성능 향상을 위해 캐쉬를 사용하고 있고 이것은 프로세서내의 많은 비율의 전력을 소모한다. 따라서 저 전력 프로세서를 설계하기 위해서는 내장 캐쉬(on-chip cache)의 전력 소모를 줄이는 것이 중요하다. 본 논문은 캐쉬 대체 전략으로 현재 많이 사용되는 LRU(Least Recently Used) 방식을 LFU(Least Frequently Used), LFUT(LFU with Threshold), FIFO(First In First Out) 방식과 관련 효율적 측면에서 비교 분석 한다.

• 한국항공운항학회:학술대회논문집
• /
• 2015.11a
• /
• pp.42-46
• /
• 2015

This paper is written about the UAS DAA(Detect and Avoidance) of EU MIDCAS project. This project has been performed from 2009 to 2014. The main mission of this project was supporting the certification agency which is ICAO, EASA, and so on. The result of this project would be the base of the UAS operation regulation in the non segregated airspace. UAS usage demand is expanding rapidly, so we also start the development of the regulation, the research of SAA technologies and LRU.