• International Journal of Ocean Engineering and Technology Speciallssue:Selected Papers
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• v.4 no.1
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• pp.22-30
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• 2001

A new concept wave absorber is proposed. It is a net type wave absorber. Its efficiency was reported in another publication. Since it is based on new concept, the traditional wave absorber theory is not applicable. It is modeled by introducing damping terms in linearized free surface boundary conditions in this study. The length and the thickness of the wave absorber are modeled by the length and the coefficient of the damping terms. Series of experiments are carried out to get the data for the coefficients of the damping term. The boundary element method is adopted to solve the system. The predicted wave heights show excellent agreement with those of experiments when the lengths of the incoming waves are within the length of the wave absorber.

• International Journal of Automotive Technology
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• v.7 no.2
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• pp.129-137
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• 2006

The representative interactive flamelet(RIF) concept has been applied to numerically simulate the combustion processes and pollutant formation in the HSDI diesel engine. In order to account for the spatial inhomogeneity of the scalar dissipation rate, the eulerian particle flamelet model using the multiple flamelets has been employed. The vaporization effects on turbulence-chemistry interaction are included in the present RIF procedure. the results of numerical modeling using the rif concept are compared with experimental data and with numerical results of the widely-used ad-hoc combustion model. Numerical results indicate that the rif approach including the vaporization effect on turbulent spray combustion process successfully predicts the ignition delay characteristics as well as the pollutant formation in the HSDI diesel engines.

• 한국신재생에너지학회:학술대회논문집
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• 2011.05a
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• pp.166.2-166.2
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• 2011

Incheon Bay of Korea is one of the most famous regions for high tidal range. Ministry of Land, Transport and Maritime Affairs(MLTM) has implemented preliminary investigation for tidal power energy development in this area since 2006. Through field observations, various kinds of marine data consisting of depth and geography, marine weather, tidal currents, wave, seawater characteristics, geology, marine ecosystem and marine environment were gathered. To use these data efficiently for the determining of feasibility of developing and appropriateness of project scale, spatial data management and application system is essential. Therefore, in this study, the concept, methodology and procedure of spatial data modeling are defined for tidal energy development. Spatial data modeling consists of essential model relating to tidal energy directly and optional model including environmental factors. Essential model is composed with fundamental elements like as depth, geography, and several numerical modeling results(tide, tidal current, wave).

• The Transactions of the Korean Institute of Power Electronics
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• v.17 no.1
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• pp.67-76
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• 2012

This paper proposes the aggregated modeling and control of integated boost-flyback converter (IBFC) for understanding of dynamics characteristic and designing of relevant controller. The basic concept of the aggregated modeling is to substitute the boost or the flyback converter with an equivalent current source. Since each converter with equivalent current source corresponds to the basic boost and flyback converters, the overall mathematical process is significantly simplified for the modeling. Afterwards each result is combined to construct the complete model of the IBFC, and the relevant controller is designed through the achieved small-signal model. Simulation and experimental results show excellent agreement with the theoretical expectations.

• Journal of Mechanical Science and Technology
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• v.16 no.7
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• pp.1009-1018
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• 2002

The Representative Interactive Flamelet (RIF) concept has been applied to numerically simulate the combustion processes and pollutant formation in the direct injection diesel engine. Due to the ability for interactively describing the transient behaviors of local flame structures with CFD solver, the RIF concept has the capabilities to predict the auto-ignition and subsequent flame propagation in the diesel engine combustion chamber as well as to effectively account for the detailed mechanisms of soot formation, NOx formation including thermal NO path, prompt and nitrous 70x formation, and reburning process. Special emphasis is given to the turbulent combustion model which properly accounts for vaporization effects on the mixture fraction fluctuations and the pdf model. The results of numerical modeling using the RIF concept are compared with experimental data and with numerical results of the commonly applied procedure which the low-temperature and high-temperature oxidation processes are represented by the Shell ignition model and the eddy dissipation model, respectively. Numerical results indicate that the RIF approach including the vaporization effect on turbulent spray combustion process successfully predicts the ignition delay time and location as well as the pollutant formation.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.5 no.11
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• pp.2121-2142
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• 2011

In this paper, we propose an e-Learning process control model that aims to graphically describe and automatically generate the manifest of sequencing prerequisites in packaging SCORM's content aggregation models. In specifying the e-Learning activity sequencing, SCORM provides the concept of sequencing prerequisites to be manifested on each e-Learning activity of the corresponding tree-structured content organization model. However, the course developer is required to completely understand the SCORM's complicated sequencing prerequisites and other extensions. So, it is necessary to achieve an efficient way of packaging for the e-Learning content organization models. The e-Learning process control model proposed in this paper ought to be an impeccable solution for this problem. Consequently, this paper aims to realize a new concept of process-driven e-Learning content aggregating approach supporting the e-Learning process control model and to implement its e-Learning process modeling system graphically describing and automatically generating the SCORM's sequencing prerequisites. Eventually, the proposed model becomes a theoretical basis for implementing a SCORM-based e-Learning process management system satisfying the SCORM's sequencing prerequisite specifications. We strongly believe that the e-Learning process control model and its modeling system achieve convenient packaging in SCORM's content organization models and in implementing an e-Learning management system as well.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.24 no.7
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• pp.537-548
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• 2014

In this paper, horn loudspeaker modeling was suggested, investigated and verified through comparison of test results and simulation ones based on input electrical impedance curves and acoustic sensitivity ones. First, Thiele Small parameters of horn driver were identified by using pseudo loudspeaker model concept and verified in case of both closed and open horndriver. Second, cone-shaped horn models were investigated and compared with input acoustic impedance curves for real horn(cone angle $6.6^{\circ}$) and short horn(cone angle $27.9^{\circ}$). It showed that Leach model for cone horn was well described to test results, which were electrical impedance and acoustic sensitivity, compared to Lemaitre one. To represent horn system model good approximation in wide frequency range, mass correction filter and lowpass filter were adopted and consequently showed good fitted to test results.

• Korean Journal of Computational Design and Engineering
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• v.13 no.2
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• pp.121-130
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• 2008

The concept of integrated product information has been universalized so that many manufacturing industries have applied the concept to their production system. The field of PDM (Product Data Management), which is one of the core components of the integrated product information, is not an exception. Therefore, various PLM (Product Lifecycle Management) software providers are in process of suggesting the PDM solutions. As the PDM solution is widely adopted in the manufacturing industries, the successful application of the solution has been gathering more strength in manipulation of the product information. However, the standardized implementation methodology is stuck in the basic level contrast with the enhanced PDM's functionality and capability. Present study refers to the application of UML (Unified Modeling Language), which is an object oriented modeling description, to PDM system development procedure. The advantage of UML is its efficiency and effectiveness in handling complex requirement often found in PDM implementation works. This paper shows the integration of PDM and UML proposes a philosophy for the support of requirement analysis throughout the full implementation of PDM system.

• Proceedings of the Korea Society of Information Technology Applications Conference
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• 2001.05a
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• pp.121-123
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• 2001

• The Journal of Korean Institute of Communications and Information Sciences
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• v.13 no.6
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• pp.480-489
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• 1988

Although CDP stacking of common depth gathering is used to get the zero-offset-section, the exploding reflector concept is examined for the modeling of zero source to receiver offset sections in this paper. The acoustic wave equation is compared with a one way wave equation which represents the upgoing wave field only. The one way wave equation used is not derived through an expansion and, therefore, can represent dips up do 90b degrees and may not lost the signals by the dipping angles. There is apparently no simple counterpart of this equation is the space domain and it can be conveniently implemented only by a Fourier method. This paper compares their modeling technique with ray tracing and wave method for over thrust structure which is one of the geological structures are dificult to process and interpret. As a result of modeling much clean and accurate signals, especially, diffractions form the corner and dipping angles can be gathered.