• Journal of Biomedical Engineering Research
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• v.28 no.6
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• pp.791-797
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• 2007

This paper proposes a semiautomatic vertebra segmentation method that overcomes limitations of both manual segmentation requiring tedious user interactions and fully automatic segmentation that is sensitive to initial conditions. The proposed method extracts fence surfaces between vertebrae, and segments a vertebra using fence-limited region growing. A fence surface is generated by a deformable model utilizing valley information in a valley emphasized Gaussian image. Fence-limited region growing segments a vertebra using gray value homogeneity and fence surfaces acting as barriers. The proposed method has been applied to ten patient data sets, and produced promising results accurately and efficiently with minimal user interaction.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• v.20 no.1
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• pp.83-106
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• 2016

This paper reviews and compares three different methods for modeling incompressible and immiscible ternary fluid flows: the immersed boundary, level set, and phase-field methods. The immersed boundary method represents the moving interface by tracking the Lagrangian particles. In the level set method, an interface is defined implicitly by using the signed distance function, and its evolution is governed by a transport equation. In the phase-field method, the advective Cahn-Hilliard equation is used as the evolution equation, and its order parameter also implicitly defines an interface. Each method has its merits and demerits. We perform the several simulations under different conditions to examine the merits and demerits of each method. Based on the results, we determine the most suitable method depending on the specific modeling needs of different situations.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.2
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• pp.399-405
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• 2002

This paper proposes a new type of piezoactuator-driven valve system. The piezoceramic actuator bonded to both sides of a flexible beam surface makes a movement required to control the pressure at the flapper-nozzle of a pneumatic valve system. After establishing a dynamic model, an appropriate size of the valve system is designed and manufactured. Subsequently, a robust H$_{\infty}$ control algorithm is formulated in order to achieve accurate tracking control of the desired pressure. The controller is experimentally realized and control performance for the sinusoidal pressure trajectory is presented in time domain. The control bandwidth of the valve system, which directly represents the fastness, is also evaluated in the frequency domain.

• Journal of Institute of Control, Robotics and Systems
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• v.5 no.3
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• pp.267-274
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• 1999

This paper proposes an adaptive sliding mode control scheme for an autopilot design of Skid-to-Turn (STT) missiles. The feedback linearization controller eliminates nonlinear terms in STT dynamics and makes the entire system linear. But the modeling errors in dynamics and the external disturbances exert bad influence on the performance of the feedback linearization controller. To handle these uncertainties, an adaptive control scheme is developed, where a bound of the uncertainties is estimated by an adaptive law based on a sliding surface. The asymptotic output tracking is proved by using the Lyapunov stability theory. Simulations for STT missiles illustrate the validity of the proposed scheme.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.2130-2131
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• 2011

Electric fire breaks out by various causes such as electric short, overload(over current), leakage current, poor contact, static electricity, insulation deterioration, partial disconnection and etc. In this paper, we studied analysis technique for scientific and systematic judgment for distinction of electricity fire existence and nonexistence, and described about electricity fire cause analysis process for collecting physical evidences. We handled external form analysis, Substance extension analysis, X-ray transmission analysis, cross-section analysis, thermal analysis, chemical structure analysis, surface structure analysis, component analysis, electrical properties analysis, and circuit analysis by analysis technique for electricity fire cause judgment. We expect that analysis technic elevation and correct cause of fire analysis of scene of a fire investigators and analysts through this paper which see help.

• Journal of the Korea Institute of Military Science and Technology
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• v.10 no.1
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• pp.78-85
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• 2007

A gun is still one of the major weapons of a combat ship. To assess the ship's fire control capability which is influenced by tracking system, fire control algorithm, gun, the ship itself, target behavior, environment and engagement situation, simulation system for gun-oriented engagement for surface ship is needed. This paper proposes the process for designing and implementing a gun-oriented engagement simulation system using DEVS(Discrete Event Simulation Specification), which is a formalism based on the set theory. It consists of the following activities : 1) analyzing the characteristics of a gun-oriented engagement, 2) constructing the deterministic model of the combat ship of study with DEVS, 3) modeling properties of each entity showing as stochastic errors. With this process, the gun-oriented engagement simulation system is developed and applied for the combat system under development.

• 한국지구물리탐사학회:학술대회논문집
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• 2005.09a
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• pp.11-18
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• 2005

Filament inversion routines are highly effective for target definition whenever total-field DHTEM vectors can be obtained using three-component logging tools. However most cross-hole components contain significant noise related to sensor design and errors in observation of probe rotation. Standard stacking methods can be used to improve data quality but additional statistical methods based on cross-correlation and spatial averaging of orthogonal components may be required to ensure a consistent vector migration path. Apart from assisting with spatial averaging, multiple filaments generated for successive time-windows can provide additional imaging information relating to target geometry and current migration. New digital receiver systems provide additional time-windows to provide better tracking options necessary for high-resolution imaging of this type.

• Korea-Australia Rheology Journal
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• v.11 no.3
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• pp.247-253
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• 1999

The growth of a spherical vapor bubble contained in a large body of upper convected Maxwell fluid is theoretically analyzed under the devolatilization condition of polymer by using a Galerkin FEM in the Lagrangian frame. Using the finite element technique, a fully explicit numerical scheme is developed both for the calculation of pressure distribution and for the tracking of bubble surface. Oscillatory behavior in bubble radius is observed during growth and the oscillatory behavior is found to be due to the interaction of mass transfer resistance and elasticity. It is found that the elasticity of fluid accelerates the growth and removal of volatile component. It is also found that the bubble growth in the devolatilization of polymers is affected by both mass transfer resistance and viscoelasticity of fluids.

• Journal of computational fluids engineering
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• v.12 no.3
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• pp.41-46
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• 2007

Dynamic behavior of immiscible gas bubble attached to the wall in channel flow plays very important role in many engineering applications. Special attention has been paid to micro direct methanol fuel cell(${\mu}$DMFC) where surface tension becomes dominant factor with minor gravitational effect due to its reduced size. Therefore, displacement of $CO_2$ bubble generating on a cathode side in ${\mu}$DMFC can be very difficult and efficient removal of $CO_2$ bubbles will affect the overall machine performance considerably. We have focused our efforts on studying the dynamic behavior of immiscible bubble attached to the one side of the wall on 2D rectangular channel subject to external shear flow. We used Level Contour Reconstruction Method(LCRM) which is the simplified version of front tracking method to track the bubble interface motion. Effects of Reynolds number, Weber number, advancing/receding contact angle and property ratio on bubble detachment characteristic has been numerically identified.

• Proceedings of the KOSOMBE Conference
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• v.1994 no.05
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• pp.32-34
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• 1994

An automatic multiframe procedure for tracking signalized points on multiple, differently moving discontinuous surface is described. The position of markers which attached on human body give us some important information such as velocity, acceleration, angular velocity and angular acceleration, etc, of the rigid objects. Generally, the detected objects occufying some area in images rather than a point because of the generic size of the marks or the smeared effects of the camera. To solve the problem we used a modified clustering algorithm.