• International Journal of Reliability and Applications
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• v.12 no.1
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• pp.49-60
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• 2011

The geometric process (GP) has been widely used for modeling failure and repair time sequences of repairable systems. The GP is mathematically tractable but restrictive in reliability applications since it actually assumes that the mean function of inter-failure times sequence asymptotically decreases to zero; and the mean function of successive repair times sequence asymptotically increases to infinity. This is generally unrealistic from an engineering perspective. This paper presents three extended GP models for modeling reliability deterioration and improvement (or growth) process. The extensions maintain the advantage of mathematical tractability of GP model. Their usefulness and appropriateness are illustrated with three real-world examples.

• IEMEK Journal of Embedded Systems and Applications
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• v.5 no.2
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• pp.67-76
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• 2010

Although both functional verification and performance evaluation are necessary for the development of effective and reliable communication systems, they have been often performed independently; by functional modeling with formal language tools and by performance modeling with professional network performance evaluation tools, respectively. Separate and repeated modeling of one system, however, would often result in cost increase and inconsistency between the models. This paper proposes an integrated model design approach in order to overcome this problem that evaluates the performance of a communication protocol designed in SDL with SDL-OPNET model conversion. The proposed technique generates OPNET skeleton code from Tau-generated C code of the SDL model by analyzing the relations between SDL and OPNET models. IEEE 802.2 LLC protocol was used as an example of model conversion to show the applicability and effectiveness of the proposed technique.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.10
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• pp.1748-1753
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• 2010

This paper suggests an improved technique to establish the modeling regarding steady and transient state on three phase-in one cryostat type HTS(High Temperature Superconducting) cable. The proposed modeling is established using EMTP/ATPDraw and TACS and MODELS provided by that. It has higher accuracy than the conventional method, as the actual HTS cable is modelled. Steady and transient state analysis performed by EMTP/ATPDraw calculate the current of conductor, shield and former, respectively. In case of the transient state modeled quench state occurred by a single line-to-ground fault, current of conductor shield and former are also calculated, respectively. Especially, various fault resistances and angles are considered to improve the reliability during transient state analysis. Analysis results reveal that the proposed technique improves the accuracy of modeling.

• Journal of the Korean Operations Research and Management Science Society
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• v.15 no.2
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• pp.85-95
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• 1990

Structured modeling provides a formal mathematical framework, language, and computer-based environment for conceiving, representing, and manipulating a wide variety of model. It provides a natural framework for integrated modeling owing to its explicit representation power for computational dependencies among submodles. Nevertheless, it doesn't seem to offer a systematic way of composing a structured model from submodels. In order to develop a systematic way, this paper discusses three key issues : (1) Genus structure for model composition, (2) Storage of structured models, and (3) Integration of structured models. To formalize and visualize the approach, a programming module is developed to implemented the step-by-step integration.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2011.10a
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• pp.607-613
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• 2011

In this study, structural vibration analyses for a 5MW offshore wind wind-turbine model have been performed for different substructure models. The efficient equivalent modeling method based on computational multi-body dynamics are applied to the finite element models of the present offshore wind turbines. Monopile and tri-pod substructure types of the typical offshore wind-turbine are considered herein. Detailed finite element modeling concepts and boundary conditions are described and the comparison results for previous analyses are presented in order to show the verification of the present numerical approach. Campbell diagrams are also present to investigate the rotational resonance characteristics of the offshore wind-turbines with different substructures.

• Proceedings of the Korea Water Resources Association Conference
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• 2007.05a
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• pp.58-66
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• 2007

This paper introduces the new generic dynamic neuro-fuzzy local modeling system (DNFLMS) that is based on a dynamic Takagi-Sugeno (TS) type fuzzy inference system for complex dynamic hydrological modeling tasks. The proposed DNFLMS applies a local generalization principle and an one-pass training procedure by using the evolving clustering method to create and update fuzzy local models dynamically and the extended Kalman filtering learning algorithm to optimize the parameters of the consequence part of fuzzy local models. The proposed DNFLMS is applied to develop the inference model to forecast the flow of Waikoropupu Springs, located in the Takaka Valley, South Island, New Zealand, and the influence of the operation of the 32 Megawatts Cobb hydropower station on springs flow. It is demonstrated that the proposed DNFLMS is superior in terms of model accuracy, model complexity, and computational efficiency when compared with a multi-layer perceptron trained with the back propagation learning algorithm and well-known adaptive neural-fuzzy inference system, both of which adopt global generalization.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.179-179
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• 2012

Low pressure radio-frequency glow discharges are investigated using theoretical modeling and various experimental diagnostic methods. In the calculations, global models and transformer models are developed to understand the chemical kinetics as well as the electrical properties such as the effective collision frequency, the heating mechanism and the power transferred to the plasma electrons. In addition, Boltzmann equation solver is used to compensate the effect of the electron energy distribution function (EEDF) shape in the global model, and the general expression of energy balance for non-Maxwellian electrons is developed. In the experiments, a number of traditional plasma diagnostic methods are used to compare with calculated results such as Langmuir probe, optical emission spectroscopy (OES), optical absorption spectroscopy (OAS) and two-photon absorption laser-induced fluorescence (TALIF). These theoretical and experimental methods are applied to understand several interesting phenomena in low pressure ICP discharges. The chemical and physical properties of low pressure ICP discharges are described and the applications of these methods are discussed.

• Asia pacific journal of information systems
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• v.8 no.2
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• pp.69-83
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• 1998

Some simulation tools have been developed to support business process reengineering. These tools can be used to not only analyze an as-is model of the existing process but also assess the potential value and feasibility of to-be models. But most of them are restricted to analyzing and redesign of the workflow only. Little attention is paid to the organization of people and their roles. This paper Presents a new methodology for business process simulation modeling and analysis. The methodology is based on the concepts of roles and customer-supplier chains. So the proposed methodology allows for tracking people and their roles affected by reengineering the business process. It enables one to analyze and evaluate not only workflow, but roles that are part of the flow. This paper developed a simulator to systematically construct simulation models and conduct simulations easily and efficiently. A case study is also presented as an illustrative example.

• Journal of Integrative Natural Science
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• v.7 no.4
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• pp.234-240
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• 2014

C-C chemokine receptor type 4 (CCR4) is a chemokine receptor with seven transmembrane helices and it belongs to the GPCR family. It plays an important role in asthma, lung disease, atopic dermatitis, allergic bronchopulmonary aspergillosis, cancer, inflammatory bowel disease, the mosquito-borne tropical diseases, such as dengue fever and allergic rhinitis. Because of its role in wide spectrum of disease processes, CCR4 is considered to be an important drug target. Three dimensional structure of the protein is essential to determine the functions. In the present study homology modeling of human CCR4 was performed based on crystal structure of CCR5 chemokine receptor. The generated models were validated using various parameters. Among the generated homology models the best one is selected based on validation result. The model can be used for performing further docking studies to identifying the critical interacting residues.

• Proceedings of the IEEK Conference
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• 2006.06a
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• pp.521-522
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• 2006

This paper presents behavioral models using SIMULINK and Verilog-a for a PLL based fractional-N frequency synthesizer. The SIMULINK modeling was built in the frequency-time mixed domain whereas the Verilog-a modeling was built purely in the time domain. The simulated results of the two models were verified to show the same performance within the error tolerance. This top-down design method can provide the readiness for the transistor-level design.