• Proceedings of the Korean Information Science Society Conference
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• 2006.06c
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• pp.334-336
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• 2006

본 논문에서는 계층적인 센서 네트워크에서 하위 센서 노드의 인증이나 센싱된 정보의 암호화를 위해 사용할 수 있는 키를 관리하기 위하여 키 선분배를 기본으로 키 재분배 방법을 제공하는 키 관리 메커니즘을 제안한다. 본 키 관리의 특징은 첫째, 중앙 관리의 약점을 극복하기 위해 키 관리를 다른 aggregator 노드들에 분산시켰다. 둘째, SINK 노드는 키의 재분배를 위한 키 스페이스를 제외하고, 이미 분배된 키에 대해서는 어느 노드에게 어떤 키를 분배했는지 또는 그 키 자체를 저장하지 않고, 키 계산을 위한 일부 정보만 저장하고 있다가 노드가 메시지에 첨부하여 주는 키 정보를 이용해 사용된 키를 간단히 계산하며, 키 풀의 확장이 용이하여 확장성을 제공한다. 마지막으로 계산 및 메모리 측면에서의 오버헤드 분석을 통해 제안된 키 관리의 확장성 제공을 입증한다.

• Proceedings of the Korean Society of Computer Information Conference
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• 2019.07a
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• pp.383-384
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• 2019

본 논문에서는 이더리움 기반 블록체인 확장성 문제해결을 위해 데이터 저장방법인 Merkle patricia tree를 응용하여 데이터에 따라 트리 이원화 사용을 제안한다. 이 연구는 시스템 자원인 CPU와 메모리를 효율적으로 사용하여 트랜잭션 처리량을 최대화하고, 작업시간을 최소화하기 위함이다. 본 논문에서는 기존 이더리움 블록체인의 트랜잭션 처리속도와 확장성 향상을 목표로 하며. 기존의 방식과 비교하여 제안을 분석한다.

• Journal of KIISE:Computer Systems and Theory
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• v.32 no.4
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• pp.177-185
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• 2005

NAND-type flash memory is becoming increasingly popular as a large data storage for mobile computing devices. Since flash memory is an order of magnitude more expensive than magnetic disks, data compression can be effectively used in managing flash memory based storage systems. However, compressed data management in NAND-type flash memory is challenging because it supports only page-based I/Os. For example, when the size of compressed data is smaller than the page size. internal fragmentation occurs and this degrades the effectiveness of compression seriously. In this paper, we present an efficient flash compression layer (FCL) for NAND-type flash memory which stores several small compressed pages into one physical page by using a write buffer Based on prototype implementation and simulation studies, we show that the proposed scheme offers the storage of flash memory more than $140\%$ of its original size and expands the write bandwidth significantly.

• The KIPS Transactions:PartA
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• v.13A no.2 s.99
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• pp.137-146
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• 2006

Shared Memory Multiprocessor (SMP) systems adopting Chip-level MultiThreading (CMT) technology are becoming mainstream servers in commercial applications and High Performance Computining (HPC) applications as well. OpenMP has become the standard paradigm to parallelize applications for SMP mostly because of its ease of use. As the demand for more computing power in HPC applications is growing rapidly, obtaining high performance and scalability for these applications parallelized using OpenMP API's will become more important. In this paper, we study the performance and scalability of HPC applications parallelized using OpenMP, SPEC OMPL (standard OpenMP benchmark suite), on the Sun Fire E25K server which adopts CMT technology. We also study the effect of CMT on SPEC OMPL.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.15 no.9
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• pp.1947-1954
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• 2011

There are various attacks such as tampering, bypassing and spoofing which are caused with system-wide vulnerabilities of Windows operating system. The underlying operating system is responsible for protecting application-space mechanisms against such attacks. This paper provides the implementation of mandatory access control known as multi-level security (MLS) rating with TCSEC-B1 level on th kernel of Windows$^{TM}$. By adding especially the protection feature against tampering memory of processes to the security kernel, this implementation meets the responsibility against system-wide vulnerabilities.

• Journal of Korean Society of Archives and Records Management
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• v.20 no.3
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• pp.161-166
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• 2020

"Gyeonggi-do Memory," established and operated by Gyeonggi-do Cyber Library, is a local digital archive aiming to broaden the access to Gyeonggi-do's cultural resource records. Since 2014, the library has been expanding its digital information service, starting with the said archive. Through cooperation with various cultural institutions in the province, it builds the digital archive by collecting numerous records. In particular, the archive is expected to establish itself as a repository that stores records of production or dealing in Gyeonggi-do and a platform to share with researchers and citizens.

• Journal of the Korean Data and Information Science Society
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• v.12 no.2
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• pp.95-102
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• 2001

최적의 SVM 가중치를 선택하는 방법 중에서 메모리와 속도의 문제를 해결하는 방법 중 하나가 커널애더트론 방법(Kernel Adatron, KA)이다. 본 연구에서는 KA방법을 제곱무감각손실함수까지 확장을 한 알고리즘을 개발한다. 그리고 추정해야 될 라그랑제 배수(Lagrange multiplier)의 수를 반으로 줄이는 알고리즘을 제시한다. 그리고 제시된 알고리즘의 효율성을 여러 모의실험을 통해서 입증한다.

• Journal of the Institute of Convergence Signal Processing
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• v.7 no.3
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• pp.136-142
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• 2006

Existing buffer management schemes for shared-memory output queueing switches can be classified into two types: In the first type, some constant amount of memory space is guaranteed to each virtual queue using static queue thresholds. The static threshold method (ST) belongs to this type. On the other hand, the second type of approach tries to maximize the buffer utilization in 머 locating buffer memories. The complete sharing (CS) method is classified into this type. In the case of CS, it is very hard to protect regular traffic from mis-behaving traffic flows while in the case of ST the thresholds can not be adjusted according to varying traffic conditions. In this paper, we propose a new buffer management method called weighted dynamic thresholds (WDT) which can process packet flows based on loss priorities for quality-of-service (QoS) functionalities with fairly high memory utilization factors. We verified the performance of the proposed scheme through computer simulations.

• Journal of Korea Spatial Information System Society
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• v.6 no.1 s.11
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• pp.3-17
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• 2004

With the rapid growth of the Internet geographic information services through the WWW such as a location-based service and so on. Web GISs (Geographic Information Systems) have also come to be a cluster-based architecture like most other information systems. That is, in order to guarntee high quality of geographic information service without regard to the rapid growth of the number of users, web GISs need cluster-based architecture that will be cost-effective and have high availability and scalability. This paper proposes the design of the cluster-based web GIS with high availability and scalability. For this, each node within a cluster-based web GIS consists of main memory spatial databases which accomplish role of caching by using data declustering and the locality of spatial query. Not only simple region queries but also the proposed system processed spatial join queries effectively. Compare to the existing method. Parallel R-tree spatial join for a shared-Nothing architecture, the result of simulation experiments represents that the proposed spatial join method achieves improvement of performance respectively 23% and 30% as data quantity and nodes of cluster become large.

• The Transactions of the Korea Information Processing Society
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• v.4 no.3
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• pp.821-830
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• 1997

The directory-based cache coherence scheme is an attractive approach to solve the caceh coherence problem in a large-scale shared-memory multiprocessor.However, the exsting directory-based schemes have some problens such as the enormous storage overhead for a directory, the long invalidation latency, the heavy network condes-tion, and the low scalability.For resolving these problems, we propose a new directroy- based caceh coherence scheme which is suitable for building scalable, shred-memory multiprocessors.In this scheme, each directory en-try ofr a given memory block is a number-balanced binaty tree(NBBT) stucture.The NBBT has several proper-ties to effciently maintain the directory for the cache consistency such that the shape is unique, the maximum depth is [log$_2$n], and the tree has the minimum number of leaf nodes among the binarry tree with n nodes.Therefore, this scheme can reduce the storage overhead, the network traffic, and the inbalidation latency and can ensutr the high- scalability the large-scale shared-memory multiprocessors.