• Proceedings of the Korean Society of Computational and Applied Mathematics Conference
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• 2003.09a
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• pp.13.1-13
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• 2003

The Markovian arrival process with marked transitions (MMAP) is useful in modeling input processes of stochastic system with several types. Especially, the MMAP can be used to model the phenomena where the correlation of different types is considered. In this talk we discuss modeling issues for the queue with three types of customers; ordinary customers, negative customers and disasters which are correlated by using MMAP. We also present the recent results and further studies.

• Korean Journal of Computational Design and Engineering
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• v.16 no.3
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• pp.167-177
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• 2011

This paper describes an ontology-based intelligent CAD system for injection mold design, which has been developed based on a commercial CAD system called Unigraphics and an ontological framework for representing the implicit design knowledge as well as the explicit based on the extended function-behavior-structure (FBS) engineering design model that includes the constraint. The system also provides various convenient solid modeling capabilities for mold design and the design process modeling capability that facilitates mold redesign process.

• Proceedings of the Korean Society for Emotion and Sensibility Conference
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• 2002.05a
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• pp.3-8
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• 2002

This paper introduces the basic concept of computational modeling of perception processes for multimedia data. Such processes are modeled as hierarchical inter- and intra- relationships amongst information in physical, physiological, psychological and cognitive layers in perception. Based on our framework, this paper gives the algorithms for content-based retrieval for multimedia database systems.

• Korean Journal of Computational Design and Engineering
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• v.13 no.3
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• pp.187-199
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• 2008

This paper describes a C++ class hierarchy of implicit objects for geometry modeling and processing. This class structure provides a software kernel for integrating many various models and methods found in current implicit modeling areas. The software kernel includes primitive objects playing a role of unit element in creating a complex shape, and operator objects used to construct more complex shape of implicit object formed with the primitive objects and other operators. In this paper, class descriptions of these objects are provided to better understand the details of the algorithm or implementation, and its instance examples to show the capabilities of the object classes for constructive shape geometry. In addition, solid modeling system shown as an application example demonstrates that the proposed implicit object classes allow us to carry out modern solid modeling techniques, which means they have the capabilities to extend to various applications.

• Korean Journal of Computational Design and Engineering
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• v.16 no.2
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• pp.114-125
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• 2011

Construction industries worldwide have moved to Building Information Modeling environment in conjunction with IT technology progress. Korean domestic construction market is in the midst of enthusiastically adopting BIM technique and the public sectors try to apply the method to their projects. Difficulties have been introduced, however, in doing so mainly due to the complexity in reflecting the distinctions of the public cost estimate requirements to BIM modeling. The main objective of this study is to propose four kinds of BIM property information modeling methodologies which would be used in the quantity surveys of the public construction projects. To evaluate the applicability of the suggested modeling methods, the research performed a case study.

• Korean Journal of Computational Design and Engineering
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• v.12 no.5
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• pp.395-404
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• 2007

Feature-based modeling and history-based modeling are the two main paradigms that are used in most of current CAD systems. Although these modeling paradigms make it easier for designers to create solid model, it may pose dependency constraints on features that are interacting one with another. When editing such features, these constraints often cause unpredictable and unacceptable results. For example, when a parent feature is deleted, the child features of the parent feature are also deleted. This entails re-generations of the deleted features, which requires additional modeling time. In order to complement this situation, we propose a method to delete only the features of interest by disconnecting the dependency constraints. This method can provide designers with more efficient way of model modification.

• Korean Journal of Computational Design and Engineering
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• v.12 no.4
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• pp.283-297
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• 2007

Seamless data integration in the CAx chain of the CAD/CAPP/CAM/CNC has been achieved to a high degree, but research concerning the transfer of data from conceptual sketches to a CAD system should be carried out further. This paper presents a method for reconstructing a 3D model from a freehand sketch. Sketch-based modeling research can be classified into gestural modeling methods and reconstructional modeling methods. This research involves the reconstructional modeling method. Here, Mitani's seminal work, designed for box-shaped 3D model using a predefined template, is improved by leveraging a relational template and specialized for automotive design. Matching between edge graphs of the relational template and the sketch is formulated and solved as the assignment problem using the feature vectors of the edges. Including the stroke preprocessing method required to generate an edge graph from a sketch, necessary procedures and relevant techniques for implementing the template-based modeling method are described. Examples from a working implementation are given.

• Journal of Computational Design and Engineering
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• v.3 no.3
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• pp.286-294
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• 2016

In this paper we present an efficient technique for sketch-based 3D modeling using automatically extracted image features. Creating a 3D model often requires a drawing of irregular shapes composed of curved lines as a starting point but it is difficult to hand-draw such lines without introducing awkward bumps and edges along the lines. We propose an automatic alignment of a user's hand-drawn sketch lines to the contour lines of an image, facilitating a considerable level of ease with which the user can carelessly continue sketching while the system intelligently snaps the sketch lines to a background image contour, no longer requiring the strenuous effort and stress of trying to make a perfect line during the modeling task. This interactive technique seamlessly combines the efficiency and perception of the human user with the accuracy of computational power, applied to the domain of 3D modeling where the utmost precision of on-screen drawing has been one of the hurdles of the task hitherto considered a job requiring a highly skilled and careful manipulation by the user. We provide several examples to demonstrate the accuracy and efficiency of the method with which complex shapes were achieved easily and quickly in the interactive outline drawing task.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2011.10a
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• pp.614-622
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• 2011

In this study, the computational structural dynamic modeling of floating offshore wind turbine system is presented using efficient equivalent modeling technique. Structural dynamic behaviors of the offshore floating platform with 5MW wind turbine system have been analyzed using computational multi-body dynamics based on the finite element method. The considered platform configuration of the present offshore wind turbine model is the typical spar-buoy type. Equivalent stiffness and damping properties of the floating platform were extracted from the results of the baseline model. Dynamic responses for the floating wind turbine models are presented and compared to investigate its structural dynamic characteristics. It is important shown that the results of the present equivalent modeling technique show good and reasonable agreements with those by the fully coupled analysis considering complex floating body dynamics.

• Journal of The Korean Association of Information Education
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• v.23 no.6
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• pp.607-619
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• 2019

As software education was introduced through the 2015 revised curriculum, various research activities have been carried out to improve the computational thinking of learners beyond the existing ICT literacy and software utilization education. With this change, the purpose of this study is to examine the research trends of various research activities related to computational thinking which is emphasized in software education. To this end, we extracted the key words from 190 papers related to computational thinking subject published from January 2014 to September 2019, and conducted frequency analysis, word cloud, connection centrality, and topic modeling analysis on the words. As a result of the topical modeling analysis, we found that the main studies so far have included studies on 'computational thinking education program', 'computational thinking education for pre-service teacher education', 'robot utilization education for computational thinking', 'assessment of computational thinking', and 'computational thinking connected education'. Through this research method, it was possible to grasp the research trend related to computational thinking that has been conducted mainly up to now, and it is possible to know which part of computational thinking education is more important to researchers.