• International Journal of Control, Automation, and Systems
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• v.6 no.6
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• pp.915-927
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• 2008

Networked control systems(NCSs) have gained increasing attention in recent years due to their advantages and potential applications. The network Quality-of-Service(QoS) in NCSs always fluctuates due to changes of the traffic load and available network resources. To handle the network QoS variations problem, this paper presents an intelligent scheduling control method for NCSs, where the sampling period and the control parameters are simultaneously scheduled to compensate the effect of QoS variation on NCSs performance. For NCSs with network-induced delays and packet dropouts, a discrete-time switch model is proposed. By defining a sampling-period-dependent Lyapunov function and a common quadratic Lyapunov function, the stability conditions are derived for NCSs in terms of linear matrix inequalities(LMIs). Based on the obtained stability conditions, the corresponding controller design problem is solved and the performance optimization problem is also investigated. Simulation results are given to demonstrate the effectiveness of the proposed approaches.

• Journal of Computing Science and Engineering
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• v.2 no.1
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• pp.44-73
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• 2008

There is general agreement that the problem of data semantics has to be addressed for XML data to become machine-processable. This problem can be tackled by defining a semantic mapping between an XML schema and an ontology. Unfortunately, creating such mappings is a tedious, time-consuming, and error-prone task. To alleviate this problem, we present a solution that heuristically discovers semantic mappings between XML schemas and ontologies. The solution takes as input an initial set of simple correspondences between element attributes in an XML schema and class attributes in an ontology, and then generates a set of mapping formulas. Once such a mapping is created, it is important and necessary to maintain the consistency of the mapping when the associated XML schema and ontology evolve. In this paper, we first offer a mapping formalism to represent semantic mappings. Second, we present our heuristic mapping discovery algorithm. Third, we show through an empirical study that considerable effort can be saved when discovering complex mappings by using our prototype tool. Finally, we propose a mapping maintenance plan dealing with schema evolution. Our study provides a set of effective solutions for building sustainable semantic integration systems for XML data.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.8
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• pp.3701-3727
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• 2016

Recently Service Function Chaining (SFC) is promising to innovate the network service mode in modern networks. However, a feasible implementation of SFC is still difficult due to the need to achieve functional equivalence with traditional modes without sacrificing performance or increasing network complexity. In this paper, we present a configurable network service chaining (CNSC) mechanism to provide services for network traffics in a flexible and optimal way. Firstly, we formulate the problem of network service chaining and design an effective service chain construction framework based on integrating software-defined networking (SDN) with network functions virtualization (NFV). Then, we model the service path computation problem as an integer liner optimization problem and propose an algorithm named SPCM to cooperatively combine service function instances with a network utility maximum policy. In the procedure of SPCM, we achieve the service node mapping by defining a service capacity matrix for substrate nodes, and work out the optimal link mapping policies with segment routing. Finally, the simulation results indicate that the average request acceptance ratio and resources utilization ratio can reach above 85% and 75% by our SPCM algorithm, respectively. Upon the prototype system, it is demonstrated that CNSC outperforms other approaches and can provide flexible and scalable network services.

• Journal of the Korean Society for Nondestructive Testing
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• v.15 no.1
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• pp.299-309
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• 1995

A geometrical inverse heat conduction problem is solved for the development of Infrared Computerized-Axial-Tomography (IR CAT) Scan by using a boundary element method in conjunction with regularization procedure. In this problem, an overspecified temperature condition by infrared scanning is provided on the surface, and is used together with other conditions to solve the position of an unknown boundary (cavity). An auxiliary problem is introduced in the solution of this problem. By defining a hypothetical inner boundary for the auxiliary problem domain, the cavity is located interior to the domain and its position is determined by solving a potential problem. Boundary element method with regularization procedure is used to solve this problem, and the effects of regularization on the inverse solution method are investigated by means of numerical analysis.

• Journal of Digital Convergence
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• v.19 no.10
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• pp.15-20
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• 2021

The crisis of university must be overcome by emphasizing the acquisition and use of knowledge for students to participate in and solve contemporary and diverse social/regional problems through educational method innovation. University classes should be a way of contributing to solving human problems, the UN's Sustainable Development Goals(SDGs) and various issues in the community. This study focused on project-based learning to cultivate socially engaged and problem-solving talents. In addition, a problem definition toolkit model was produced and tested to improve problem solving ability. Through follow-up research, I plan to develop a performance measurement model corresponding to the field application-improvement-feedback of Living Lab project classes, and suggest a method that universities can easily apply to the existing curriculum.

• The Journal of the Korea Contents Association
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• v.7 no.2
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• pp.161-169
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• 2007

This study examines the effects of learner's metacognition and scaffolding types on problem solving processes by examined 49 undergraduates to identify effective scaffolding type in Web-based PBL. This study classifies problem solving processes as defining the problem, developing solutions, making selections and justifications for the Proposed solution(s), and monitoring the solution. Moreover, it classifies scaffolding types as subject-related scaffolding and process-related scaffolding. As a result, the upper metacognition group showed higher performance only in monitoring solutions than the lower metacognioon group. This study also showed that offered scaffolding effects are not statistically significant. However, the lower metacognition group showed higher performance when subject-related scaffolding was offered and the upper metacognition group showed higher performance when process-related scaffolding was offered in making selections and justifications for the proposed solution(s) and monitoring solution. This study, based on the result of research, can partially verify the effects of learner's metacognition on problem solving processes and interaction effects between scaffolding and metacogniton in Web-based PBL.

• Journal of Engineering Education Research
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• v.14 no.1
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• pp.64-73
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• 2011

This study had a purpose to examine that problem solving process through the product design and conceptual design in engineering design education affected the improvement of students' self-directed learning ability. For this, we conducted in-depth interview with students that taken the introductory engineering design course. The main findings were as follows. First, the importance of diagnosing the learning needs and defining the problem was realized. Second, the importance of organizing lesson plans for problem solving and performing it out systematically was acknowledged. Third, they knew that continuous modification and supplements were needed, and also reviews and checks were needed after the evaluation process. Based on these results, the problem solving process of engineering design education affected a positive effect to students' self-directed learning.

• The Journal of Korean Association of Computer Education
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• v.11 no.4
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• pp.1-12
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• 2008

This paper proposes basic algorithmic thinking based problem models applicable immediately without additional learnings and it problems basic problems and evaluation methods using material factors in an elementary course of mathematics For these purposes, an algorithmic thinking based problem model and it's basic problem models are proposed based on flowchart design methods with 5 degrees of difficulties. And algorithmic thinking based basic problems are developed by applying the proposed basic problem models into material domain in an elementary course of mathematics. And this paper proves the validity of developed basic problems in defining then as algorithmic thinking based basic problems through experiments and statistical analyses. The experimental results are analyzed in views of variety and effectiveness evaluation of answer algorithms and suitability of allocating 5 degrees of difficulties to the developed basic problems.

• Journal of the Korean earth science society
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• v.25 no.4
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• pp.205-213
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• 2004

The purpose of this study was to design the coaching strategies for the problem based learning and examine 'the problem situation' to analyze the process of learning as it applies to the students' perception on problem based learning. The steps of this model were as follows: 1) presentation of the problem situation 2) confrontation of the problem 3) know/ need to know 4) definition of the problem statement 5) collection and sharing of information 6)generation of possible solutions 7) assessment of the best fit of solutions 8) presentation of the solution. Problem-based learning steps and coaching strategies were designed and implemented to 2nd grade high school students for the environment teaching unit. The results demonstrated that group discussion in the know/need to know step was most helpful for students to review what they know and generate solutions. At first students tend to state problems widely but through repeated group discussions they gradually clarified the problems. In the students' personal reflection notes and perception questionnaire of problem-based learning, many students especially showed difficulties in defining the problem statement. In contrast they participated actively in the learning process and express their opinions enthusiastically. Therefore, this study suggests that developing problem situation based on real context is of great importance for implementing a problem based teaming model continuously.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.663-668
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• 2003

This paper presents a new observation system which is useful to observe the scene of the remote controlled robot vision. This system is composed of a motionless camera and head motion detector with a motion sensor. The motionless camera has a fish eye lens and is for observing a hemisphere space. The head motion detector has a motion sensor is for defining an arbitrary subspace of the hemisphere space from fish eye lens. Thus processing the angular information from the motion sensor appropriately, the direction of face is estimated. However, since the fisheye image is distorted, it is unclear image. The partial domain of a fish eye image is selected by head motion, and this is converted to perspective image. However, since this conversion enlarges the original image spatially and is based on discrete data, crevice is generated in the converted image. To solve this problem, interpolation based on an intensity of the image is performed for the crevice in the converted image (space problem). This paper provides the experimental results of the proposed observation system with the head motion detector and perspective image conversion using the proposed conversion and interpolation methods, and the adequacy and improving point of the proposed techniques are discussed.