• Journal of computational fluids engineering
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• v.17 no.4
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• pp.32-40
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• 2012

Efficient Global Optimization (EGO) method is a global optimization technique which can select the next sample point automatically by infill sampling criteria (ISC) and search for the global minimum with less samples than what the conventional global optimization method needs. ISC function consists of the predictor and mean square error (MSE) provided from the kriging model which is a stochastic metamodel. Also the constrained EGO method can minimize the objective function dealing with the constraints under EGO concept. In this study the constrained EGO method applied to the RAE2822 airfoil shape design formulated with the constraint. But the noisy CFD data caused the kriging model to fail to depict the true function. The distorted kriging model would make the EGO deviate from the correct search. This distortion of kriging model can be handled with the interpolation(p=free) kriging model. With the interpolation(p=free) kriging model, however, the search of EGO solution was stalled in the narrow feasible region without the chance to update the objective and constraint functions. Then the accuracy of EGO solution was not good enough. So the three-step search method was proposed to obtain the accurate global minimum as well as prevent from the distortion of kriging model for the noisy constrained CFD problem.

• Journal of the Society of Naval Architects of Korea
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• v.51 no.5
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• pp.349-355
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• 2014

The resistance test of a high speed craft such as planing ship is performed with a high speed towing carriage instead of ordinary towing carriage because of the speed limitation. In the resistance test using high speed towing carriage, the model ship is fixed to the carriage to restrain the running attitude for enough measuring time. Such method is called fixed model test method. In the fixed model test method, to get the appropriate running attitude, the model test is iteratively repeated until the trim moment and lift force are close to zero. In this research, trim free model test method is investigated to reduce the number of iteration. And, the limitation of towing speed range in the trim free model test method is investigated.

• Microbiology and Biotechnology Letters
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• v.20 no.6
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• pp.704-706
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• 1992

A model peptide, N-carbobenzoxy-L-phenylalanyl-L-phenylalanine methyl ester, was synthersized with free and immobilized thermolysin in a microaqueous system. The model peptide was formed mostly during the initial phase of the reaction. The yields of the compound with free and immobilized thermolysin after 4hr of reaction were 77.8 and 71.2, respectively.

• Structural Engineering and Mechanics
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• v.41 no.1
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• pp.67-81
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• 2012

Differential Quadrature Method (DQM) is a powerful method which can be used to solve numerical problems in the analysis of structural and dynamical systems. In this study the governing equation which represents the free vibration of coupled shear walls is solved using the DQM method. A one-dimensional model has been used in this study. At the end of study various examples are presented to verify the accuracy of the method.

• Journal of the Korean Society of Visualization
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• v.9 no.3
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• pp.59-64
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• 2011

In this study the change of free surface vortex is expressed through the time volume fraction using multiphase unsteady condition in sump, because in previous studies of the pump sump did not represent the behavior of the free surface vortex exactly due to the reason it was calculated using single phase and steady condition. The reliability of the computational analysis is verified through comparing experimental results with that of present numerical analysis. Homogeneous free surface model is used to apply interactions of air and water. The results show that the free surface vortex can be identified on the isotropic surface at air volume fraction 1%~5%. The vortices make an air column from the free surface to the sump intake and are created and destroyed repeatedly. The behavior of free surface vortex at numerical analysis is quite similar to experimental test. The result of vortex motion according to time, works on a cycle.

• Journal of Korea Port Economic Association
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• v.21 no.3
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• pp.19-34
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• 2005

The purpose of this paper is to introduce the new way of location choice for free trade zone in Busan area by using Obata and Ishii(2003) model of preference discrimination score. And also, this paper investigates the result of Choi, Bong-ho(200l) that deals with the choice of tariff free area in Busan area. Empirical main results are as follows: First, the North Port(Sinsundae)and the New Busan Port are efficient. Final winer of location choice for free trade zone is the North Port(Sinsundae). Second, the ranking result of this paper for 10 potential sites of free trade zone shows the almost similar to that of Choi, Bong-ho(200l). Policy planner for location choice of free trade zone should introduce the preference discrimination score method by Obata and Ishii(2003), because this method shows the very positive empirical results like questionaire method by expert groups and common people in Busan which should cause the much time and much money.

• Journal of the Institute of Convergence Signal Processing
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• v.9 no.3
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• pp.208-212
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• 2008

This paper proposes a model of a voice communication using bluetooth and a mobile, and implements a hands-free for this model. A Proposed model uses bluetooth for a voice network, and is possible to share a voice with a great number of people using preemptive algorithm proposed in this paper. There are two types of models. One is a model only using a hands-free, the other is a model using a mobile. Second model uses a scatternet and a call forwarding service for a call on a voice communication. In case of using a scatternet, scatternet is composed of a piconet of a voice communication and a piconet of a call. In case of using a call forwarding service, the mobiles share information of each others before formation of a network.

• Journal of the Society of Naval Architects of Korea
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• v.57 no.5
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• pp.262-270
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• 2020

An outdoor free-running model test system was designed for assessing ship maneuverability with test uncertainty. The test model was a surface combatant of tumblehome hull geometry. The straight forward tests were conducted first to obtain the relationship between the propeller revolution rate and advance speed. During the outdoor tests, the propeller revolution rate to achieve a certain Froude number condition was higher than that in the indoor free-running model tests. Turning circle and zigzag tests for evaluating ship maneuverability criteria were carried out at the propeller revolution rate determined by the straight forward test results. The random and systematic standard uncertainties of maneuvering criteria were obtained by repeated tests and comparison with the indoor free-running model test results, respectively. The test uncertainty was largely dominated by the systematic standard uncertainty, while the random standard uncertainty was small with good repeatability.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.19 no.1
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• pp.1-6
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• 2011

The free-wing tilt-body aircraft is researched in the flight performance characteristics such as short take-off and landing capability, and reduced sensitivity to gust and center of gravity (CG) change. Due to the main wing separating from the fuselage, the high tiltable empennage, and the stub-wing strongly influencing from the propeller wake, the resulting vehicle aerodynamics and flight dynamics are quite different from those of a conventional fixed-wing aircraft. Using the governing flight dynamics model was studied previously, all of speed and body tilt angle is simulated to determine the flight envelope by a non-linear 3-DOF flight simulation analysis. Though flight performance and trimmability are studied, the flight model of free-wing tilt-body aircraft is to reduce the hidden risk and to achieve the successful flight test. It is analyzed the flight characteristics that distinguishes free-wing tilt-body aircraft from the conventional aircraft.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.19 no.4
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• pp.1-5
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• 2011

The free-wing tilt-body aircraft is researched in the flight performance characteristics for center of gravity (CG) change. All of speed, body tilt angle and center of gravity change are simulated to determine the flight envelope by a non-linear 3-DOF mathematical model. In flight, this aircraft configuration changes by the tiltable empennage. Then, flight dynamics distinguishes from those of a conventional fixed-wing aircraft. Though flight performance and trimmability are studied by CG change, the flight model of free-wing tilt-body aircraft is to reduce the hidden risk and to achieve the successful flight test. It is analyzed the flight characteristics by CG change that distinguishes free-wing tilt-body aircraft from the conventional aircraft.