• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.24.3-24
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• 2001

In cases where strong a priori knowledge about the object being analyzed is available, it can be embedded into the formulation of the snake model. When prior knowledge of shape is available for a specific application, information concerning the shape of the desired objects can be incorporated into the formulation of the snake model as an active contour model. In this paper we show Five points algorithm can be applied to design invariant energy.

• The Transactions of the Korea Information Processing Society
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• v.4 no.3
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• pp.731-746
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• 1997

The usage of object models for the development of software has been frowung due to the prevalence of the ob-ject oriented paradigm.The object moedels produced as results of requirments analysis and design activities are vety veneficial to the implementation phase.It is even possible for source code to be genrated automatically if object models are concrete enough.Therefore system analyzers and desingners should make an dffort to refine theabstrace ogject model defined at.an early stage in order to achieve a more conrete object model.In general,re-fining an abstrace object model into a concrete model depends too much on the desigver's infromal experience.In this paper,we persent the refinement techniques required for concreting an abstract object model bassed on OMT(Object Modeling Technique)'s notation,We will discuss the definition of the abstraction level of an object model and the transformational rules of refinement.These transformational rules are currently applied to the design of a software tool,named Process Modeler,which is a major component of the software development process modeling system for ICS(Information Communication Service). Finally we can achieve a concrete object model which can easily be translated into C++ source code.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1996.10a
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• pp.45-51
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• 1996

The combined shear and compression behaviors of seismic isolation rubber bearings are analyzed using the hyperelasticity material option of the ABAQUS computer program. The purpose of the analysis is to predict the behavior of laminated rubber bearing before the several tests. Some kinds of strain energy density functions are used as constitutive law for rubber itself having the hyperelasticity. The results are compared with test data peformed in Italy The analysis results show a little different with experimental results depending on the constitutive model and the refinement of finite element. The high order form of strain energy density functions results in good agreements and the mesh refinement above two for one rubber layer is enough to get good results.

• Structural Engineering and Mechanics
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• v.76 no.3
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• pp.379-393
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• 2020

In this paper, we propose an automatic procedure to improve the accuracy of finite element solutions using enriched 2D solid finite elements (4-node quadrilateral and 3-node triangular elements). The enriched elements can improve solution accuracy without mesh refinement by adding cover functions to the displacement interpolation of the standard elements. The enrichment scheme is more effective when used adaptively for areas with insufficient accuracy rather than the entire model. For given meshes, an error for each node is estimated, and then proper degrees of cover functions are applied to the selected nodes. A new error estimation method and cover function selection scheme are devised for the proposed adaptive enrichment scheme. Herein, we demonstrate the proposed enrichment scheme through several 2D problems.

• Journal of the Korean Society of Visualization
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• v.17 no.2
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• pp.67-72
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• 2019

In this study, we investigate the non-reacting and reacting performance of single nozzle for post H class gas turbine by using commercial CFD tool, CONVERGE, based on adaptive mesh refinement. By varying swirl number and mixing length of base nozzle design. Through the numerical analysis, basic phenomena can be well described with respect to fuel concentration for non-reacting flow, temperature distribution, velocity vector and combustion outlet temperature distribution for reacting flow. However, there are rooms for improvements in model accuracy by comparing test results. Comparison between numerical analysis are planning for further study.

• Nuclear Engineering and Technology
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• v.55 no.8
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• pp.2854-2863
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• 2023

Objective: To present a hybrid approach that incorporates a constrained beam-hardening estimator (CBHE) and deep learning (DL)-based post-refinement for metal artifact reduction in dental cone-beam computed tomography (CBCT). Methods: Constrained beam-hardening estimator (CBHE) is derived from a polychromatic X-ray attenuation model with respect to X-ray transmission length, which calculates associated parameters numerically. Deep-learning-based post-refinement with an artifact disentanglement network (ADN) is performed to mitigate the remaining dark shading regions around a metal. Artifact disentanglement network (ADN) supports an unsupervised learning approach, in which no paired CBCT images are required. The network consists of an encoder that separates artifacts and content and a decoder for the content. Additionally, ADN with data normalization replaces metal regions with values from bone or soft tissue regions. Finally, the metal regions obtained from the CBHE are blended into reconstructed images. The proposed approach is systematically assessed using a dental phantom with two types of metal objects for qualitative and quantitative comparisons. Results: The proposed hybrid scheme provides improved image quality in areas surrounding the metal while preserving native structures. Conclusion: This study may significantly improve the detection of areas of interest in many dentomaxillofacial applications.

• Transactions of the Korean Society of Mechanical Engineers
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• v.19 no.8
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• pp.2030-2038
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• 1995

In this study, three turbulent flame propagation models are compared using experimentally measured data of a 4 valves/cylinder spark-ignition engine. First two conventional models are B.K model and GESIM combustion model. The burning rates calculated from the two models are compared with the burning rates calculated from measured pressure data using the one-zone heat release analysis. GESIM combustion model predicts burning rates closer to the data acquired from the experiment in wide operating ranges than B-K model does. The third model is refined based on GESIM combustion model by including the effect of flame stretch, turbulent length scale band pass filter and a variable that considers flame size and the area of flame contacting the cylinder wall surface. The refined combustion model predicts burning rates closer to experimental results than GESIM combustion model does. Also, the refined combustion model predicts flame radius close to the experimental result measured by using optical fiber technique.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.27 no.12
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• pp.1681-1690
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• 2003

The effect of roughness is a change in the velocity and turbulence distributions near the surface. Turbulence models with surface roughness effect are applied to the fully developed flow in a two-dimensional, rough wall channel. Modified wall function model, low-Reynolds number k-$\varepsilon$ model, and k-$\omega$ model are selected for comparison. In order to make a fair comparison, the calculation results are compared with the experimental data. The modified wall function model and the low-Reynolds number k-$\varepsilon$ model require further refinement, while the k-$\omega$ model of Wilcox performs remarkably well over a wide range of roughness values.

• Journal of the Korea Institute of Military Science and Technology
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• v.13 no.1
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• pp.41-49
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• 2010

In this paper, we propose a hierarchical RAM simulation model framework which are used to analyze the RAM specifications on the concept refinement phase. The hierarchical RAM simulation model framework consists of RAM simulation models, class library and each model's input and output data lists. The hierarchical RAM simulation models are co-operated with 3 kinds of model - type I, II, III. Type I, II models are used to analyze the target operational availability and Type III is used to establish the initial RAM specifications. Each model's input and output data lists are defined by considering each model's purpose of RAM analysis. The class library is arranged with each model's classes for implementing the hierarchical simulation models. The proposed framework may be applied for executing the RAM activities effectively.

• The KIPS Transactions:PartC
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• v.8C no.5
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• pp.607-614
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• 2001

With a remarkable growth and expansion of Internet, the security issues emerged from intrusions and attacks such as computer viruses, denial of services and hackings to destroy information have been considered as serious threats for Internet and the private networks. To protect networks from those attacks, many vendors have developed various security systems such as firewalls, intrusion detection systems, and access control systems. However, managing those systems individually requires too much work and high cost. Thus, in order to manage integrated security management and establish consistent security management for various security products, the policy model of PN-ISMS (Policy Based Integrated Security Management System) has become very important. In this paper, present the hierarchical policy model which explore the refinement of high-level/conceptual policies into a number of more specific policies to form a policy hierarchy. A formal method of policy description was used as the basis of the mode in order to achieve precision and generality. Z-Notation was chosen for this propose. The Z-Notation is mathematical notation for expressing and communicating the specifications of computer programs. Z uses conventional notations of logic and set theory organized into expressions called schemas.