• Proceedings of the Korea Information Processing Society Conference
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• 2013.05a
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• pp.68-70
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• 2013

대량의 데이터를 효과적으로 저장하고 관리하기 위해서 클라우드 스토리지 시스템에서는 분산 파일 시스템 기술이 이용되고 있다. 그러나 데이터가 증가함에 따라 분산 파일 시스템을 이용함에도 스토리지 확장 비용이 증가하게 된다. 본 논문에서는 분산 파일 시스템의 스토리지 확장 비용을 줄이기 위해서 우리는 중복제거 파일 시스템을 적용한 분산 파일 시스템에서의 청크 배치 기법을 제안한다. 오픈 소스 기반의 분산 파일 시스템인 MooseFS 에 중복제거 파일 시스템인 lessfs 를 적용함으로써 스토리지의 가용공간을 늘릴 수 있으며, 이는 스토리지 확장 비용을 줄이는 효과를 가져온다. 또한, 동일한 청크는 같은 청크 서버에 배치 시킴으로써 중복제거 기회를 높인다. 실험을 통해서 제안 시스템의 중복제거량과 성능에 대해서 평가한다.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.27 no.4
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• pp.971-980
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• 2017

Data deduplication can be utilized to reduce storage space in cloud storage services by storing only a single copy of data rather than all duplicated copies. Users who are concerned the confidentiality of their outsourced data can use secure encryption algorithms, but it makes data deduplication ineffective. In order to reconcile data deduplication with encryption, Liu et al. proposed a new server-side cross-user deduplication scheme by exploiting password authenticated key exchange (PAKE) protocol in 2015. In this paper, we demonstrate that this scheme has side channel which causes insecurity against the confirmation-of-file (CoF), or duplicate identification attack.

• Journal of KIISE:Software and Applications
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• v.37 no.8
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• pp.647-652
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• 2010

Esterel is an imperative synchronous language well-adapted to control-intensive systems. When an Esterel program is translated to a circuit, the synchronizer of a parallel statement may be executed more than once in a clock; the synchronizer is called schizophrenic. Existing compilers cure the problems of schizophrenic parallel synchronizers using logic duplications. This paper proposes the conditions under which a synchronizer causes no problem in circuits when it is executed more than once in a clock. In addition we design a detection algorithm based on those conditions. Our algorithm detects schizophrenic parallel synchronizers that have to be duplicated in Esterel source codes so that compilers can save the size of synthesized circuits

• The KIPS Transactions:PartA
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• v.15A no.3
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• pp.135-140
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• 2008

This paper describes a high-speed CMOS demultiplexer using redundant multi-valued logic (RMVL). The proposed circuit receives serial binary data and is converted to parallel redundant multi-valued data using RMVL. The converted data are reconverted to parallel binary data. By the redundant multi-valued data conversion, the RMVL makes it possible to achieve higher operating speeds than that of a conventional binary logic. The implemented demultiplexer consists of eight integrators. Each integrator is composed of an accumulator, a window comparator, a decoder and a D flip flop. The demultiplexer is designed with TSMC $0.18{\mu}m$ standard CMOS process. The validity and effectiveness are verified through the HSPICE simulation. The demultiplexer is achieved the maximum data rate of 20 Gb/s and the average power consumption of 95.85 mW.

• Journal of KIISE:Computer Systems and Theory
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• v.35 no.9_10
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• pp.421-428
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• 2008

A. Ghafoor proposed Even networks as a class of fault-tolerant multiprocessor networks in [1] and analyzed so many useful properties include node disjoint paths. By introducing node disjoint paths in [1], fault diameter of Even networks is d+2(d=odd) and d+3(d=even). But the lengths of node disjoint paths proved in [1] are not the shortest. In this paper, we show that Even network Ed is node symmetric. We also propose the shortest lengths of node disjoint paths using cyclic permutation, and fault diameter of Even networks is d+1.

• The Journal of the Korea Contents Association
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• v.16 no.1
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• pp.470-481
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• 2016

The purpose of this study is to identify the actual condition of poly-victimization and examine the difference in the levels of psychological adaptation and delinquency by victimization types among adolescents. A total 6,174 cases from '2013 Adolescent Deviant Behaviors and Policy Issues' of NYPI was used for the analysis. Main findings are that 8.3% of adolescents exposed to more than two types of victimization and 2.1% of them experienced more than three types of victimization. There were significant differences in the levels of psychological adaptation and delinquency by victimization types. Study findings were discussed in terms of implications for research and intervention of adolescent poly-victimization.

• Journal of KIISE:Computer Systems and Theory
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• v.36 no.5
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• pp.429-436
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• 2009

Odd network was introduced as one model of graph theory. In [1], it was introduced as a class of fault-tolerant multiprocessor networks and analyzed so many useful properties such as simple routing algorithms, maximal fault tolerance, node axsjoint path, etc. In this paper, we sauw a construction algorithm of edge-axsjoint spanning trees in Odd network $O_d$. Also, we prove that edge-disjoint spanning tree generated by our algorithm is optimal edge-disjoint spanning tree.

• 한국공간정보시스템학회:학술대회논문집
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• 2003.11a
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• pp.147-152
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• 2003

TPR-tree는 이동체의 위치 데이터에 대해 현재 및 미래 위치 질의를 지원하기 위하여 시간 함수 기반의 경계사각형(Sounding Rectangle)으로 이동체를 색인한다. 경계사각형의 각 축은 가장 빠른 속도로 이동하는 이동체의 속도 값을 이용하여 시간에 따라 확장한다. 경계사각형 영역의 확장으로 중복(overlap)이 심화되고 사장영역(dead space)이 커지는 문제가 있다. 따라서 시간이 지날수록 영역질의 시 성능이 떨어진다. 이 논문에서는 시간이 지남에 따라 발생하는 노드간의 심한 중복과 사장영역을 줄이기 위해 중복이 심한 두 개의 단말노드를 강제 합병하고 재분할하는 강제 합병 정책과 이동체의 삭제가 발생한 노드의 모든 이동체들을 강제적으로 재삽입하는 삭제노드 강제 재삽입 정책과 삭제가 발생한 노드와 중복되는 노드들의 이동체들을 강제적으로 재삽입하는 중복 노드 강제 재삽입 정책을 이용한다. 강제 합병 정책과 삭제 노드 강제 재삽입 정책, 그리고 중복 노드 강제 재삽입은 TPR-tree의 구조를 점진적으로 재구성하기 때문에 이동체의 현재 분포를 고려하여 색인 구조를 동적으로 개선하는 장점을 가진다.

• Journal of KIISE:Software and Applications
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• v.34 no.6
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• pp.503-518
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• 2007

Normalization transforms one parent genotype to be consistent with the other before crossover. In this paper, we explain how normalization alleviates the difficulties caused by non-synonymously redundant encodings in genetic algorithms. We define the encodings with maximally non-synonymous property and prove that the encodings induce uncorrelated search spaces. Extensive experiments for a number of problems show that normalization transforms the uncorrelated search spaces to correlated ones and leads to significant improvement in performance.

• Smart Media Journal
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• v.4 no.4
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• pp.33-38
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• 2015

Cloud storage server do not detect duplication of conventionally encrypted data. To solve this problem, Convergent Encryption has been proposed. Recently, various client-side deduplication technology has been proposed. However, this propositions still cannot solve the security problem. In this paper, we suggest a secure source-based deduplication technology, which encrypt data to ensure the confidentiality of sensitive data and apply proofs of ownership protocol to control access to the data, from curious cloud server and malicious user.