• International Journal of Aeronautical and Space Sciences
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• v.6 no.2
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• pp.17-22
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• 2005

As one of validation tool for attitude determination system, we have used various constraints using priori information which is known through base vector set up. However these conventional constraints cannot guarantee validity in terms of final solutions such as Euler angle. So we suggest attitude boundary concept to verify the final attitude solution on the flying airplane, it is based on the combination of velocity based attitude estimation technique and ambiguity resolution. we can say it can check invalid solution effectively at just one epoch without repeatability test of resolved cycle ambiguity. In this paper we show that the suggested constraint can effectively reject incorrectly resolved cycle ambiguity the conventional constraints have missed.

• International Journal of Aeronautical and Space Sciences
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• v.11 no.1
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• pp.41-48
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• 2010

In the present study, the turbulent flow fields around a circular cylinder at $Re=3.6{\times}10^6$ were investigated based on an unstructured mesh technique, and the comparisons between URANS(S-A, SST) and hybrid RANS/LES(DES, SAS) methods for the simulation of high Reynolds number flow have been conducted. For this purpose, unsteady characteristics of vortex shedding and time-averaged quantities were compared. A quasi-steady solution-adaptive mesh refinement was also made for the URANS and hybrid RANS/LES approaches. The results showed that the simple changes in the turbulent length scale or source term of turbulent models made the flow fields less dissipative and more realistic in hybrid RANS/LES methods than the URANS approaches.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.16 no.11
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• pp.1194-1200
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• 1991

The FEM is a computer-aided mathematical technique for obtaining approximate solution to the differential equations. The pointwise convergence defines the relationship between the mesh size and the tolerance. This will play an important role in improving quality of finite element approximate solution. In the paper. We evaluate the convergence on a certain unknown point with a 1-irregular mesh refinement and spectral order enrichment. This means that the degree of freedom is minimized within a tolerance.

• Structural Engineering and Mechanics
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• v.22 no.4
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• pp.433-447
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• 2006

The problem of very large deflection of a circular cantilever arc device subjected to inward or outward polar force is studied. An exact elliptic integral solution is derived for the two cases and the results are checked using large displacement finite element analysis via the ANSYS package by performing a new novel modeling simulation technique for this problem. Excellent agreements have been obtained between the exact analytical solution and the numerical approach. From this study, a design chart for engineers is developed to predict the required value for the inward polar force for the device to switch on for a given angle forming the circular arc (${\theta}_o$). This study has several interesting applications in mechanical engineering, integrated circuit technology, nanotechnology and especially in microelectromechanical systems (MEMs) such as a MEM circular device switch subjected to attractive or repulsive magnetic forces due to the attachments of two magnetic poles at the fixed and at the free end of the circular cantilever arc switch device.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2002.05a
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• pp.625-631
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• 2002

A module design aims to develop product architecture that consists physically detachable units such as module. To develop the system of module design, this paper suggests the methodology of part grouping, evaluation of modularization of a product for improving modularization. To determine modules, module concept is proposed to satisfy the objectives of a modular design. Therefore, there are functional, structural, and process modularizations in a modular concept. Module grouping can be accomplished by using an optimization model that maximizes the sum of the weighting. The present study proposes the p-median model and the direct clustering technique. The optimal clustering solution can be obtained by comparing two clustering techniques. To find the best solution among part groups, evaluation of modularization is performed based on the concept of module design. For the evaluation of modularization, evaluation criteria of modularization are used in the matrix table.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.34S no.8
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• pp.92-103
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• 1997

This paper proposes a new gray-level image segmentation method using GA(genetic algorithm) and an ACA(adaptive clustering algorithm). The solution in the general GA can be moving because of stochastic reinsertion, and suffer from the premature convergence problem owing to deficiency of individuals before finding the optimal solution. To cope with these problems and to reduce processing time, we propose the new GBR algorithm and the technique that resolves the premature convergence problem. GBR selects the individual in the child pool that has the fitness value superior to that of the individual in the parents pool. We resolvethe premature convergence problem with producing the mutation in the parents population, and propose the new method that removes the small regions in the segmented results. The experimental results show that the proposed segmentation algorithm gives better perfodrmance than the ACA ones in Gaussian noise environments.

• Bulletin of the Korean Chemical Society
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• v.24 no.1
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• pp.32-36
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• 2003

Co nanoparticles were prepared by the reverse micelle technique (NaBH₄reduction of cobalt chloride in a reversed micelle solution of didodecyldimethylammoniumbromide (DDAB)/toluene). The size and the shape of Co nanoparticles could be easily controlled by changing the water contents and micelle concentrations, and the solubility of Co nanoparticles was systematically tuned by choosing appropriate surface capping organic ligand molecules. Furthermore, a novel nanofabrication process was clearly demonstrated, which generated oxide over-coated Co nanorods from Co nanoparticles in organic solution by slow oxidation with an external magnetic field.

• Proceedings of the IEEK Conference
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• 2002.07c
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• pp.1851-1854
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• 2002

The Internet with conventional routing scheme cannot meet user demands driven from drastic growth in the Internet user and various service and traffic type. MPLS(Multi Protocol Label Switching) was introduced to the Internet fur solution to resolve this problem. MPLS is a paradigm to integrate higher layer’s software routing functions including layer-3 routing with layer-2 switching. But, the exponential growth of Internet traffic brings out of label space. One scalable solution to cope with this problem is to introduce flow merge technique, i. e. a group of flows is forwarded using the same label. Specially, IETF(Internet Engineering Task Force) recommends that ATM based MPLS system may include VC merge function, so it is scalable to increase of internet traffic. We implemented the MPLS LER system that includes the look-up and forwarding function in incoming path and VC merging function and limited traffic management function in outgoing path. This paper describes the implementation of the LER’s outgoing parts.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.59 no.3
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• pp.245-252
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• 2010

This paper proposes a constrained multi-area dispatch scheduling algorithm applicable to interconnected power system operations. The dispatch scheduling formulated as an MIP problem can be efficiently computed by GBD algorithm. GBD guarantees adequate computation speed and solution convergence by reducing the dimension of the dispatch scheduling problem. In addition, the regional decomposition technique based on ADM is introduced to obtain efficient inter-temporal OPF solution. It can find the most economic dispatch schedule incorporating power transactions without each regional utility's private information open.

• Proceedings of the KIEE Conference
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• 2000.07d
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• pp.2918-2920
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• 2000

A new multi-planar interpolation technique for three dimensional medical image rendering is proposed. In medical imaging. resolution in the slice direction is usually much lower than those in the transverse planes. The proposed method is based on the solution of the Laplace's equation used in the electrostatics. In this approach. two contours in the source and destination planes for a given object is assumed to have equi-potentials. Some preprocessing and post-processing including scaling. displacement. rotation from the centers of mass are involved in the algorithm. The interpolation solution assumes mostly smoothing changes in between the source and destination planes. Simultaneous multiple interpolation planes are inherently obtained in the proposed method. Some experimental and simulation results are shown.