• 한국정보통신학회논문지
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• 제18권1호
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• pp.63-71
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• 2014

본 논문에서는 Active-Active 방식의 웹서버 이중화 방법에 관해 연구하였다. Rsync과 crontab을 이용하여 웹서버간에 주기적인 복사가 이루어지도록 하여 동일한 상태를 유지시켰다. 로드밸런싱서버가 웹서버를 교대로 실행하여 부하를 분산하고, 빠른 서비스가 제공되도록 하였다. 또한 임의의 웹서버에 장애가 발생하더라도 또 다른 웹서버에 의해 서비스가 계속 유지되도록 하였다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제10권8호
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• pp.3689-3700
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• 2016

It is not practically feasible to apply hardware-based fault-tolerant schemes, such as hardware replication, in mobile devices. Therefore, software-based fault-tolerance techniques, such as checkpoint and rollback schemes, are required. In checkpoint and rollback schemes, the optimal checkpoint interval should be applied to obtain the best performance. Most previous studies focused on minimizing the expected execution time or response time for completing a given task. Currently, most mobile applications run in real-time environments. Therefore, it is extremely essential for mobile devices to employ optimal checkpoint intervals as determined by the real-time constraints of tasks. In this study, we tackle the problem of determining the optimal inter-checkpoint interval of checkpoint and rollback schemes to maximize the deadline meet ratio in real-time systems and to build a probabilistic cost model. From this cost model, we can numerically find the optimal checkpoint interval using mathematical tools. The performance of the proposed solution is evaluated using analytical estimates.

• 환경영향평가
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• 제15권6호
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• pp.385-394
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• 2006

Land resources should be managed not only for human utilizations but also for environmental preservation. Based on that, environmental capacity should be estimated in both environmental and developmental ways. This study was performed for developing an estimation model for relative environmental capacity, considering both Development Tolerance Index(DTI), which shows environmental and ecological conservation value and is based on national environmental assessment indicators of the Korea Ministry of Environment, and Development Attractiveness Index(DAI), which shows topographical characteristics and geographical accessibility. The relative environmental capacity in this study can be helpful to coping with the conflict in planning and managing the use of land resources. The relative environmental capacity in this study, however, did not include either environmental or ecological sensitivity of land resources. This limitation should be solved through further research.

• Journal of information and communication convergence engineering
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• 제6권3호
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• pp.320-322
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• 2008

We present efficient algorithms for solving the piecewise-cubic approximation problems in the plane. Given a set D of n points in the plane, we find a piecewise-cubic polynomial curve passing through only the points of a subset S of D and approximating the other points using the uniform metric. The goal is to minimize the size of S for a given error tolerance $\varepsilon$, called the min-# problem, or to minimize the error tolerance $\varepsilon$ for a given size of S, called the min-$\varepsilon$ problem. We give algorithms with running times O($n^2$ logn) and O($n^3$) for both problems, respectively.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2008년도 춘계학술대회논문집
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• pp.373-382
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• 2008

A method to investigate the design variable tolerance effects on the variances of the response, the characteristics, and the performance of a mechanical system is presented in this paper. The Monte-Carlo method has been conventionally employed to achieve such goals. However, the Monte-Carlo method has some serious drawbacks related to the computation time and the consistent solution convergence. To resolve the drawbacks of the method, a method employing sensitivity information is proposed. Sensitivity equations for a mechanical system are obtained analytically by differentiating the multi-body formulation with respect to a design variable. By using the chain rule along with the sensitivity information, the variances of the response, the characteristics, and the performance of a dynamic system can be calculated.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제12권10호
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• pp.4774-4796
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• 2018

Wireless sensor networks are composed of a large number of inexpensive and tiny sensors used in different areas including military, industry, agriculture, space, and environment. Fault tolerance, which is considered a challenging task in these networks, is defined as the ability of the system to offer an appropriate level of functionality in the event of failures. The present study proposed an intelligent throughput descent and distributed energy-efficient mechanism in order to improve fault tolerance of the system against soft and permanent faults. This mechanism includes determining the intelligent neighborhood radius threshold, the intelligent neighborhood nodes number threshold, customizing the base paper algorithm for distributed systems, redefining the base paper scenarios for failure detection procedure to predict network behavior when running into soft and permanent faults, and some cases have been described for handling failure exception procedures. The experimental results from simulation indicate that the proposed mechanism was able to improve network throughput, fault detection accuracy, reliability, and network lifetime with respect to the base paper.

• Journal of Information Technology Applications and Management
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• 제23권1호
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• pp.25-32
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• 2016

Using a sample of employees in various hospitality organizations, we proposed that individual disposition such as tolerance for ambiguity, positve affectivity, internal locus of control, and self-efficacy, will influence hospitality employees' resitance to change. The results supported hypotheses. Ultimately, we hope the results of this study provide propoer guidelines with hospitality managers and employees to decrease thiere resistance to change such as new IS implementation and thus increase their willingness to adopt in implementing new IS.

• 한국통신학회논문지
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• 제16권11호
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• pp.1194-1200
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• 1991

유한요소법(Finite Element Method)은 컴퓨터를 이용하여 미분방정식의 근사해를 얻기위한 수학적인 기법이다. 유한요소법의 pointwise convergence는 매쉬 크기와 허용 오차와의 관계를 분석해 보려는 것이다. 이들 상호 관계에 과난 연구는 유한요소법에 의한 근사식의 질을 높이는데 중요한 계기가 되어 결과를 예측 하는데 효과적이다. 본 논문을 1-Irregular 매쉬를 이용한 세분화(refinement) 및 형상 함수의 차수 변화에 따른 미지절점(unknown node) 수의 증가에 따른 수렴성을 분석하였다.

• 한국통신학회논문지
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• 제30권5C호
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• pp.320-328
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• 2005

하이퍼 큐브는 정규적이며 결함 허용 능력을 갖고 있기 때문에 결함 허용 알고리즘을 구현하기 쉽다. 하이퍼 큐브를 이용한 결함 허용 알고리즘들이 많이 개발되었다. 이러한 알고리즘들 중에 안전(safe)과 불안정(unsafe) 개념을 이용한 알고리즘이 Masuyama등에 의해 개발되었다. 이 논문에서는 Masuyama의 알고리즘을 개선한 새로운 알고리즘을 제안하고 시뮬레이션을 통하여 성능을 비교한다.

• 공학논문집
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• 제2권1호
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• pp.73-82
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• 1997

실시간 분산처리 시스템 개발을 위한 설계 동향을 분석한 바, 기존의 실시간 분산처리 시스템은 통신, 근사치 계산, 객체지향 패러다임, 멀티프로세서 하드웨어, 동적 시간 처리 및 에러 용인 등의 특성을 반영하여 설계되고 있다. 이러한 주요 설계 요소들의 장점, 단점을 분석하여 차세대 실시간 시스템 개발을 위한 방안을 논의하였다.