• The KIPS Transactions:PartD
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• v.15D no.4
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• pp.441-450
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• 2008

Recently, access control on form-based web information systems has become one of the useful methods for implementing client systems in a service-oriented architecture. In particular, XForms language is being adopted in many systems as a description language for XML-based user interfaces and server interactions. In this paper, we propose an efficient algorithm for the evaluation of XPath-based access rules for XForms pages. In this model, an XForms page is a sequence of queries and the client system performs user interface realization along with XPath rule evaluations. XPath rules have instance-dependent predicates, which for the most part are shared between rules. For the efficient evaluation of shared predicate expressions in access control rules, we proposed a predicate graph model that reuses the previously evaluated results for the same context node. This approach guarantees that each predicate expression is evaluated for the relevant xml node only once.

• Journal of the Korea Society of Computer and Information
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• v.12 no.5
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• pp.49-56
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• 2007

This paper deals with grid job allocation and grid resource scheduling to provide a stable and quicker job processing service to grid users. In this paper, we proposed a fuzzy logic-based grid job scheduling model for an effective job scheduling in computational grid environment. The fuzzy logic-based grid job scheduling model measures resource efficiency of all grid resources by a fuzzy logic system based on diverse input parameters like CPU speed and network latency and divides resources into several groups by resource efficiency. And, the model allocates jobs to resources of a group with the highest resource efficiency. For performance evaluation, we implemented the fuzzy logic-based grid job scheduling model on the DEVS modeling and simulation environment and measured reduction rates of turnaround time, job loss, and communication messages in comparison with existing job scheduling models such as the random scheduling model and the MCT(Minimum Completion time) model. Experiment results that the proposed model is useful to improve the QoS of the grid job processing service.

• Journal of the Korea Society of Computer and Information
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• v.18 no.2
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• pp.69-76
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• 2013

Reader-to-reader interference in RFID system is occurred due to the use of limited number of frequencies, and this is the main cause of read rate reduction in the passive RFID tags. Therefore, in order to maximize the read rate under the circumstances of limited frequency resources, it is necessary to minimize the frequency interference among RFID readers. This paper presents a hybrid FDM/TDM constraint satisfaction problem models for frequency interference minimization problems of the RFID readers, and assigns optimal channels to each readers using conventional backtracking search algorithms. A depth first search based on backtracking are accomplished to find solutions of constraint satisfaction problems. At this moment, a variable ordering algorithm is very important to find a solution quickly. Variable ordering algorithms applied in the experiment are known as efficient in the graph coloring. To justify the performance of the proposed constraint satisfaction problem model, optimal channels for each readers in the passive UHF RFID system are allocated by using computer simulation satisfying various interference constraints.

• Journal of the Korea Society of Computer and Information
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• v.17 no.6
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• pp.119-130
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• 2012

In this paper, we propose ubiquitous tree management system based on GIS and smart-phone using the object-oriented design modeling to maximize the efficiency of tree management. For this, proposed system is implemented in the form of client/server (C/S). The spot tree management system as the client is based on the mobile(PDA, Smart-Phone), whereas the tree management system based on PC as the server makes use of GIS. Also, Web service method instead of CDMA used in exist studies is used for tree data communication among C/S. And problems of existing studies, that is excessive maintenance costs, accessibility shortage of variety users, connectivity shortage of geographic information system will be settled through the convergence of the proposed system development methods, GIS system, smart devices. Therefore, we verify proposed system by using the systemic unit test and qualitative assessment respectively and prove to be more excellent than the existing system based on the mobile, in terms of systemic effectiveness and extendability.

• Spatial Information Research
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• v.17 no.3
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• pp.277-285
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• 2009

Each system should have a suitable data model about their purpose for efficiently managing, analyzing, and manipulating data. And the usable range of application is determined by the data model, and suitable data models are being developed for each application. In GIS, diversity spatial data model is being developed too. The accuracy and update of the spatial data would be important for applying efficient application as well as the data modeling is important as constructing the spatial data structure. Therefore, the purposes of this research are to 1)compare domestic spatial data models with oversea spatial data models about their geometry model, topology model and visualizing method of 3D spatial data 2)to compare the features of the data model by analyzing each data structures. We 3)compare and analyze features of each spatial data models via the quantitative analysis of each spatial data models.

• Journal of The Korean Association of Information Education
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• v.14 no.3
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• pp.427-435
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• 2010

As the e-Learning plays an increasingly larger important part in education and has been increased as an alternative to offline education, academic organizations are moving ahead to set guidelines for quality assurance in e-Learning. And various quality assurance techniques in e-Learning have been developed because the e-Learning does not always match well traditional models of teaching and learning, much care needs to be taken in the design, creation and implementation of service. But the present quality assurances in e-Learning which are focused in learning objects have much problems because they use partial and static management. In this thesis we suggested dynamic quality assurance using CLD(Causal Loop Diagram) in e-Learning. The suggested method has more efficiency than existing methods and it can provide important strategies with regard to administrative issues in e-Learning.

• Journal of Digital Convergence
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• v.16 no.7
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• pp.199-211
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• 2018

Ever since Korea was geopolitically divided into North and South Korea in the 1940s, South Korea has depended on maritime transportation for global trade and logistics. Now, however, South Korea is preparing to develop a new global route for trans-Eurasia logistics passing through North Korea. Even though there are difficulties to overcome, South Korea expects that a new overland route, shorter than the existing seaways in the Europe-Asia section, will bring more frequent trade with more rapid and cost-effective logistics services in the future. Related to this issue, this study aims to proactively analyze dynamic logistics changes in South Korea when a trans-Korea railway is developed and linked with the trans-China railway and the trans-Siberian railway. This study employed a system dynamics simulation approach to model the logistics system in South Korea. The simulation results indicated that the traffic of the Uiwang inland container depot near the capital area may increase but the traffic of the Port of Busan may decrease. With supplementary research, consequently, follow-up studies on adjusting the traffic capacity in Korea are required to attain successful trans-Eurasia logistics by rail.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.38 no.8
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• pp.30-41
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• 2001

In this paper, the architecture of Dynamic GSMP V3(General Switch Management Protocol Version 3), an open interface protocol with resource management functions for efficient IP service on ATM over MPLS, is proposed and implemented in hardware. And we compare and analyze the proposed GSMP with the GSMP under standardization process in terms of CLR (Cell Loss Rate). We design the Slave block of the Dynamic GSMP V3 using SAM-SUNG SoG $0.5{\mu}m$ process, which performs functions for switch connection control in the ATM Switch. In order to compare difference performanaces between the proposed method and the conventional one, we conducts simulations using the minimum buffer search algorithm with random cell generation. The exponential results show that the proposed method leads to performance enhancement in CLR.

• Journal of the Korea Society for Simulation
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• v.20 no.3
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• pp.89-100
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• 2011

The MAGLEV (Magnetically Levitated Vehicle) system, which is under commercialization as a new transportation system in Korea, is operated by means of unmanned automatic control system. Therefore the plan of train operation should be carefully established and validated in advance. In general, when making the train operation plan, the statistically predicted traffic data is used. However, traffic wave can occur when real train service is operated, and the demand-driven simulation technology is required to review train operation plans and service qualities considering traffic wave. This paper presents a method and model to simulate the MAGLEV's operation considering continuous demand changes. For this purpose, we employed the discrete event model which is suitable for modeling the behavior of railway passenger transportation, and modeled the system hierarchically using DEVS (Discrete Event System Specification) formalism. In addition, through the implementation and experiment using DEVSim++ simulation environment, we tested the feasibility of the proposed model and it is also verified that our demand-driven simulation technology could be used for the prior review of the train operation plans and strategies.

• Journal of the Korea Society of Computer and Information
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• v.13 no.2
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• pp.51-57
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• 2008

We present a modeling of constraint satisfaction problems and provide heuristic algorithms of backtracking search to optimize the frequency assignment. Our research objective is to find a frequency assignment that satisfies all the constraints using minimum number of frequencies while maximizing the number of community radio stations served for a given area. In order to get a effective solution, some ordering heuristics such as variable orderings and value orderings are provided to minimize the backtracking in finding all solutions within a limited time. To complement the late detection of inconsistency in the backtracking, we provide the consistency enforcing technique or constraint propagation to eliminate the values that are inconsistent with some constraints. By integrating backtracking search algorithms with consistency enforcing techniques, it is possible to obtain more powerful and effective algorithms of constraint satisfaction problems. We also provide the performance evaluation of proposed algorithms by comparing the theoretical lower bound and our computed solution.