• The KIPS Transactions:PartD
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• v.11D no.5
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• pp.1143-1148
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• 2004

To develop multi-tier model or distributed architecture based distributed application needs to consider various aspects such as division of role between web-designer and software developer, defining entity and its usage, database connection and transaction processing etc. This paper presents DONSL(Data Server of Non SQL-Query) architecture that provides solution to above aspects through web-tier object modeling. This is the architecture that guarantees the transaction processing and performance between web-tier and DBMS through simplified usage of query logic property. This new conceptual framework also solves enterprise site implementation problems simplifying tier, and removing DAO(Data Access Object) and entity.

• The Korean Journal of Applied Statistics
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• v.29 no.3
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• pp.449-462
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• 2016

This paper considers a long-run variance estimation using a block bootstrap method under strong dependence also known as long range dependence. We extend currently available methods in two ways. First, it extends bootstrap methods under short range dependence to long range dependence. Second, to accommodate the observation that strong dependence may come from deterministic trend plus noise models, we propose to utilize residuals obtained from the nonparametric kernel estimation with the bimodal kernel. The simulation study shows that our method works well; in addition, a data illustration is presented for practitioners.

• Aerospace Engineering and Technology
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• v.10 no.1
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• pp.63-69
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• 2011

In this study, we developed a dispersion analysis program of the gas-generator cycle liquid propellant rocket engine by expanding the mode analysis software(GEMAT). The performance dispersions of an engine that are arisen from the internal dispersion factors of engine's sub-components were formulated and solved to find the effects of each dispersion factor. We were also able to present the calculation method to find the required pressure margin for the compensation of those dispersion to satisfy the required performances of engine. Using this method, we could propose a novel procedure of compensating during the ground firing test which would induce the performance improvement by lessening the pumps discharge pressures or augmenting the combustion chamber pressure.

• Korean Chemical Engineering Research
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• v.51 no.3
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• pp.403-406
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• 2013

This paper describes a simple route to synthesis of water-dispersible monodisperse maghemite (${\gamma}-Fe_2O_3$) nanocrystals using 6-aminohexanoic acid (AHA) as a stabilizer. The water-dispersible ${\gamma}-Fe_2O_3$ nanocrystals with an average size of 5 nm were obtained simply by addition of $Fe(CO)_5$ into an octyl ether solution containing AHA at $195^{\circ}C$ under argon condition. As-prepared AHA coated ${\gamma}-Fe_2O_3$ nanocrystals exhibited highly crystallinity and magnetic property while keeping a good dispersity in an aqueous phase. We also obtained water-dispersible AHA coated ${\gamma}-Fe_2O_3$ nanocrystals using ligand-exchange method, demonstrating that AHA can be a good candidate for preparing water-dispersible uniform metal oxide nanocrystals.

• Proceedings of the Materials Research Society of Korea Conference
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• 2006.11a
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• pp.9.1-9.1
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• 2006

• Journal of the Korean Data and Information Science Society
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• v.25 no.1
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• pp.87-95
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• 2014

In the regression model, Kang and Huh (2006) studied the estimation of the discontinuous variance function using the Nadaraya-Watson estimator with the squared residuals. The local linear estimator of the log-variance function, which may have the whole real number, was proposed by Huh (2013) based on the kernel weighted local-likelihood of the ${\chi}^2$-distribution. Chen et al. (2009) estimated the continuous variance function using the local linear fit with the log-squared residuals. In this paper, the estimator of the discontinuous log-variance function itself or its derivative using Chen et al. (2009)'s estimator. Numerical works investigate the performances of the estimators with simulated examples.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.17 no.1
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• pp.75-82
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• 2004

With an aim at eliminating the numerical dispersion error arising from the numerical simulation of stress wave propagation, numerical dispersion characteristics of the wave equation based one-dimensional finite element model are analyzed and some dispersion control scheme are proposed in this paper The dispersion analyses are carried out for two types of mass matrix, namely the consistent and the lumped mass matrices. Based on the finding of the analyses, dispersion correction techniques are developed for both the implicit and explicit schemes. For the implicit scheme, either the weighting factor for the spatial derivatives of each time level or the lumping coefficient for mass matrix is adjusted to minimize the numerical dispersion. In the case of the explicit scheme an artificial dispersion term is introduced in the governing equation. The validity of the dispersion correction techniques proposed in this study is demonstrated by comparing the numerical solutions obtained using the Present techniques with the analytical ones.

• Journal of KIISE:Computer Systems and Theory
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• v.33 no.3
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• pp.193-204
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• 2006

In most existing distributed Web systems, incoming requests are distributed to servers via Domain Name System (DNS). Although such systems are simple to implement, the address caching mechanism easily results in load unbalancing among servers. Moreover, modification of the DNS is necessary to load considering the server's state. In this paper, we propose a new dynamic load balancing method using dynamic DNS update and round-robin mechanism. The proposed method performs effective load balancing without modification of the DNS. In this method, a server can dynamically be added to or removed from the DNS list according to the server's load. By removing the overloaded server from the DNS list, the response time becomes faster. For dynamic scheduling, we propose a scheduling algorithm that considers the CPU, memory, and network usage. We can select a scheduling policy based on resources usage. The proposed system can easily be managed by a GUI-based management tool. Experiments show that modules implemented in this paper have low impact on the proposed system. Furthermore, experiments show that both the response time and the file transfer rate of the proposed system are faster than those of a pure Round-Robin DNS.

• The Korean Journal of Applied Statistics
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• v.35 no.5
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• pp.579-591
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• 2022

Functional data is collected in various fields. It is often necessary to test whether there are differences among groups of functional data. In this case, it is not appropriate to explain using the point-wise ANOVA method, and we should present not the point-wise result but the integrated result. Various studies on functional data analysis of variance have been proposed, and recently implemented those methods in the package fdANOVA of R. In this paper, I first explain ANOVA and multivariate ANOVA, then I will introduce various methods of analysis of variance for univariate and multivariate functional data recently proposed. I also describe how to use the R package fdANOVA. This package is used to test equality of weekly temperatures in Seoul and Busan through univariate functional data ANOVA, and to test equality of multivariate functional data corresponding to handwritten images using multivariate function data ANOVA.

• Journal of the Korean Institute of Intelligent Systems
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• v.15 no.4
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• pp.425-430
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• 2005

Many problems can be formulated in terms nf graphs and thus solved by graph-theoretic algorithms. This paper is concerned with finding paths between nodes over the distributed and overlapped graphs. The proposed method allows multiple agents to cooperate to find paths without merging the distributed graphs. For each graph there is a designated agent which is charged of providing path-finding service for hot graph and initiating the path-finding tasks of which path starts from the graph. The proposed method earlier on constructs an abstract graph so-called viewgraph for the distributed overlapped graphs and thus enables to extract the information about how to guide the path finding over the graphs. The viewgraph is shared by all agents which determine how to coordinate other agents for the purpose of finding paths. Each agent maintains the shortest path information among the nodes which are placed in different overlapped subgraphs of her graph. Once an agent is asked to get a path from a node on her graph to another node on another's graph, she directs other agents to provide the necessary information for finding paths.