• Journal of KIISE:Computer Systems and Theory
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• v.33 no.10
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• pp.746-758
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• 2006

Many objects existing on wide area environments have the replication characteristics according to how to categorize using their own names or properties. From the clients' requests, the existing naming and trading services have not supported with the binding service for replicated solver object with the same service type. For this reason, we present an integrated model that can support the selection of replicated object and dynamic binding services on wide-area computing environments. This model suggests provides not only location management of replicated objects but also active binding service which enables to select a least-loaded object on the system to keep the balance of load between systems. In this purpose, constructing both the service plan and model for support solver object's binding with replication property on wide area computing environments has been researched. In this paper, we showed the test environment and analyzed the performance evaluation of client/server binding procedures via integrated binding service in federation model and verified our model under the condition to see whether load balance can be applied to our model. For the performance evaluation of suggested wide area integrated binding service federation model, evaluated the integrated binding service of each domain and analyzed the performance evaluation of process for non-replication object's under federation model environment. Also, we analyzed the performance evaluation of the federation model between domains for wide area environment. From the execution results, we showed the federation model provides lowers search-cost on the physical tree structure of network.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.40 no.4
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• pp.363-372
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• 2016

When a system consisting of rigid and flexible bodies is optimized to improve its dynamic characteristics, its eigenfrequencies are typically maximized. While topology optimization formulations dealing with simultaneous design of a system of rigid and flexible bodies are available, studies on eigenvalue maximization of the system are rare. In particular, no work has solved for the case when the target frequency becomes one of the repeated eigenfrequencies. The problem involving repeated eigenfrequencies is solved in this study, and a topology optimization formulation and sensitivity analysis are presented. Further, several numerical case studies are considered to demonstrate the validity of the proposed formulation.

• Journal of KIISE:Computing Practices and Letters
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• v.14 no.7
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• pp.657-668
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• 2008

Traditional off-the-shelf file server has several potential drawbacks to store data blocks. A first drawback is a lack of practical de-duplication consideration for storing data blocks, which leads to worse storage capacity waste. Second drawback is the requirement for high performance computer system for processing large data blocks. To address these problems, this paper proposes a clustering backup system that exploits file fingerprinting mechanism for block-level de-duplication. Our approach differs from the traditional file server systems in two ways. First, we avoid the data redundancy by multi-level file fingerprints technology which enables us to use storage capacity efficiently. Second, we applied a cluster technology to I/O subsystem, which effectively reduces data I/O time and network bandwidth usage. Experimental results show that the requirement for storage capacity and the I/O performance is noticeably improved.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.14 no.6
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• pp.1465-1474
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• 1994

For a vertical wall with standing waves on its front face, the unsteady flow in a flow conduit installed through the wall is analyzed. A nonlinear standing wave theory making use of Fourier expansion is applied, and the results are verified by a hydraulic experiment. It is found that the nonlinear theory better predicts the behavior of the flow compared to its linear counterpart. The investigation of the water transmissibility through the conduit shows that the variation of the flow rate becomes larger as the standing wave height and period increase and as the length of conduit decreases. The relationship is presented by a nondimensional equation. The net flow gain per one wave period, which is directly related to water exchanging capability of the conduit, appears to be negative in both theory and experiment when the conduit is located near the bottom. The maximal flow gain occurs in the conduit whose mouth is located at the still water level. In addition, it is shown that the longer wave period and the shorter conduit length are more effective in the water exchanging performance.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.10B
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• pp.1076-1085
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• 2009

In this paper, a new method for efficient computation of CGH patterns for 3-D video images is proposed by combined use of temporal redundancy and look-up table techniques. In the conventional N-LT method, fringe patterns for other object points on that image plane can be obtained by simply shifting these pre-calculated PFP (Principle Fringe Patterns). But there have been many practical limitations in real-time generation of 3-D video holograms because the computation time required for the generation of 3-D video holograms must be massively increased compared to that of the static holograms. On the other hand, as ordinary 3-D moving pictures have numerous similarities between video frames, called by temporal redundancy, and this redundancy is used to compress the video image. Therefore, in this paper, we proposed the efficient hologram generation method using the temporal redundancy of 3-D video image and N-LT method. To confirm the feasibility of the proposed method, some experiments with test 3-D videos are carried out, and the results are comparatively discussed with the conventional methods in terms of the number of object points and computation time.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.14 no.1
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• pp.29-36
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• 2021

The amount of data generated has been growing exponentially, and the complexity of data has been increasing owing to the advancement of information technology (IT). Big data analysts and engineers have therefore been actively conducting research to minimize the analysis targets for faster processing and analysis of big data. Hadoop, which is widely used as a big data platform, provides various processing and analysis functions, including minimization of analysis targets through Hive, which is a subproject of Hadoop. However, Hive uses a vast amount of memory for data deduplication because it is implemented without considering the complexity of data. Therefore, an efficient algorithm has been proposed for data deduplication of complex structures. The performance evaluation results demonstrated that the proposed algorithm reduces the memory usage and data deduplication time by approximately 79% and 0.677%, respectively, compared to Hive. In the future, performance evaluation based on a large number of data nodes is required for a realistic verification of the proposed algorithm.

• ETRI Journal
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• v.14 no.4
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• pp.148-164
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• 1992

본 논문에서는 TDX-10 데이터베이스 데이터의 고장을 주기적으로 진단하고 복구할 수 있는 고장진단 전문가 시스팀을 제안하고 구현하였다. 실시간 환경 및 분산구조를 갖는 데이터베이스 관리 시스팀에서 데이터베이스의 효과적인 접근을 위해서 필요한 데이터베이스의 데이터 즉, 디렉토리와 딕셔너리는 매우 중요하며 고장이 발생할 경우 데이터베이스 관리시스팀에 미치는 영향은 치명적이다. 따라서, 실시간 환경을 갖는 데이터베이스 관리 시스팀에서 데이터베이스 데이터에 대한 고장 진단 및 복구는 필수적이라고 할 수 있다. 본 논문에서 제안한 고장진단 전문가 시스팀은 데이터베이스 데이터를 운용중 변하는 부분과 변하지 않는 부분으로 분류하고 미리 주어진 고장진단 규칙에 따라 진단하는 방법이다. 데이터베이스 데이터의 고장진단 데이터, 고장진단 규칙, 고장진단 데이터 생성기, 고장진단 데이터 검증기, 그리고 고장진단기로 구성되어 있다. 고장진단 데이터는 고장진단기가 데이터베이스 데이터를 주기적으로 진단하기 위하여 사용하는 마스터 데이터로서 두개가 존재한다. 고장진단 데이터 생성기는 데이터베이스 데이터의 고장진단을 위한 데이터 구조를 생성하고 데이터베이스로부터 데이터베이스를 데이터를 중복하여 읽어들이는 역할을 한다. 이와 같은 과정은 시스팀이 초기에 동작을 시작하거나 운용중 운용자에 의해서 릴레이션의 추가 및 삭제, 그리고 튜플의 추가등과 같은 사건이 발생할 경우에 이루어진다. 데이터베이스 검증기는 고장진단 데이터 생성기가 중복하여 생성한 데이터에 대해서 데이터베이스 데이터의 제작시의 초기 오류를 검증해냄으로써 데이터베이스 관리 시스팀의 안전한 운용을 가능하게 하며 고장진단기가 데이터베이스 데이터를 주기적으로 진단할 데이터를 탄생시킨다. 마지막으로 고장진단기는 주기적으로 데이터베이스 데이터의 고장을 진단하여 고장이 발생한 데이터를 미리 분류한 규칙에 따라 원래의 데이터로 복구하거나 운용자에게 보고함으로써 고장에 대비하도록 한다. 그리고 데이터베이스 상의 운용자에 의한 변경을 감지하여 고장진단 데이터의 재생성을 지시한다. 본 논문에서 제시하고 구현한 데이터베이스 데이터의 고장진단 및 복구를 위한 전문가 시스팀은 실시간 환경과 고장허용 환경, 분산 구조 그리고 빈번한 접근을 갖는 데이터베이스 관리 시스팀에서 아주 중요한 역할을 할 수 있다.

• Journal of the Korean Geographical Society
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• v.33 no.2
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• pp.325-338
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• 1998

본 연구에서는 시.공 복합적인 선형 점 자료를 대상으로 시간과 공간을 함께 고려했을 때 자료 내에 군집(cluster)-시.공 복합 군집(space-time cluster)-이 존재하는 가를 검증하는 방법에 대해 논의하고, 실제 교통사고지점의 분포자료를 분석하여 군집의 유무를 통계적으로 검증하였다. 통계 분석의 결과 다음과 같은 사실이 확인되었다. 첫째, Knox의 분할표 방법과 Mantel의 역수 변환을 이용한 일반화된 회귀분석방법 모두 임계 거리 및 임계 시간 간격의 선택이 분석결과에 영향을 미친다. 둘째, 이러한 임의성을 극복하기 위해 다양한 임계 거리 및 임계 시간 간격(혹은 부가 상수)에 대해 반복 실험한 결과, 일부 임계값의 조합에서 시간과 공간이 서로 독립적이라는 귀무가설을 기각할 수 있는 증거가 발견되었다. 셋째, 시.공 복합 군집의 파악에 가장 적합한 임계 거리와 임계 시간 간격은 공간적으로는 7000m, 시간적으로는 14일 혹은 21일이다. 마지막으로, 통계 분석과정에서 자료에 존재하는 중복 기록 사고들의 존재가 밝혀짐으로써 시.공 복합군집 검증이 탐험적 자료 분석(exploratory data analysis)의 도구로서 가지는 가치를 확인할 수 있었다.

• Proceedings of the Korea Information Processing Society Conference
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• 2014.04a
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• pp.479-482
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• 2014

최근 모바일 컴퓨팅 환경이 발전함에 따라 모바일 디바이스 이용자들에게 다양한 서비스를 제공하기 위한 방법으로 클라우드 스토리지 서비스가 주목받고 있으며, 여러 장치의 데이터 동기화를 지원해준다. 이러한 편리성을 제공하고 있지만, 개인과 기업의 핵심 자료 유출에 따른 보안 이슈가 중요한 문제로 대두되고 있기 때문에, 클라우드 스토리지 보안 검증의 중요성도 증대되었다. 이처럼 클라우드 스토리지 서비스는 보안 검증 과정을 거친다. 본 논문에서는 기존의 클라우드 스토리지 보안 평가 가이드라인의 문제점을 분석하여 다형성, 종속성, 병렬성, 중복성 등을 고려해 효율적인 클라우드 스토리지 보안 평가를 위한 새로운 방법론을 제시 하였다. 제시한 방법론을 이용해 클라우드 스토리지 보안검증 프로세스를 설계하였다.

• Journal of Korean Society of Transportation
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• v.20 no.7
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• pp.15-22
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• 2002

Transportation project appraisal should be precise in order to increase the social welfare and efficiency, and it has been evaluated by only a single criterion analysis such as benefit/cost analysis. However, this method cannot assess some qualitative items, and cannot get a proper solution for the clash of interests among various groups. Therefore, the multi-criteria analysis, which can control these problems, is needed, and then Saaty has developed one of these methods, AHP(Analytic Hierarchy Process) method. In AHP, the project is evaluated through weighted score of the criteria and the alternatives, which is surveyed by a questionnaire of specialists. It is based on some strict suppositions such as reciprocal comparison, homogeneity, expectation, independence relationship between multi-criteria, but supposing that each criterion has independence relation with others is too difficult in two reasons. First, in real situation, there cannot be perfect independence relationship between standards. Second, individuals, even though they are specialists of that area, do not feel the degree of independence relation as same as others. This paper develops a modified AHP method for solving this dependence relationship between multi-criteria. First of all. in this method, the degree of dependence relationship between multi-criteria that the specialist feels is surveyed and included to the weighted score of multi-criteria This study supposes three methods to implement this idea. The first model products the degree of dependence relationship in the first step for calculating the weighted score, and the others adjust the result of weighted score from the basic AHP method to the dependence relationship. One of the second methods distributes the cross weighted score to each standard by constant ratio, and the other splits them using Fuzzy measure such as Bel and Pl. Finally, in order to validate these methods, this paper applies them to evaluate the alternatives which can control public resentments against Korean rail path in a city area.