• Bulletin of the Society of Naval Architects of Korea
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• v.27 no.3
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• pp.107-116
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• 1990

The liquid sloshing in an elastic tank is a fluid-structure interaction problem. It requires nonlinear analysis to solve the complicated physics involved in the large interaction of fluid-structure, the variation of dynamic characteristics of structure due to hydrodynamic loading, and the distorsion of fluid flow due to structural vibration. In this paper a Lagrangian FEM is introduced to analyze the liquid sloshing in an elastic tank assuming that the elastic wall is one degree of freedom rigid wall. Numerical integration is performed using an implicit-explicit algorithm, which is formed by mixing the predictor-corrector method and the Runge-Kutta 4th order method. The influence of dynamic characteristics of the sloshing tank on the fluid flow is discussed. The numerical method is also applied for the simulation of the wall generated wave in the tank.

• Journal of the Society of Naval Architects of Korea
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• v.37 no.4
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• pp.66-74
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• 2000

In this paper, hydroelastic responses of the very large floating structure are studied based on the linear potential theory. A theoretical method is developed to analyze the hydroelastic reponses of very large floating structures(VLFS) using the pressure distribution method and the modal expansion method. The singularities distributed on a zero draft plate at the free surfaces and hydrodynamic pressures are evaluated. The deflections of structure are expanded approximately in terms of natural mode functions of free-free beam. The calculated items are pressure distributions. vertical motions, hydrodynamic coefficients and bending moments of VLFS. The numerical results are compared with those measured by experiments.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.3 no.2
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• pp.92-99
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• 1991

A moored body in the sea is subjected to second-order wave forces as well as to linear oscillatory ones. The second-order farces contain slowly-varying components, of which the characteristic frequency can be as low as the natural frequency of horizontal motions of the moored body. As a consequence, the slowly-varying force can excite unexpectedly large horizontal excursion of the body, which may cause a serious damage on the mooring system. In design analysis of Turret-type mooring system which is one of the interesting mooring systems for a floating body. the slowly-varying drift forces and the transient motion of the system during weathervaning are very important. In this paper the slowly-varying drift forces were calculated by using the Quadratic Transfer Function with considering the second order free-wave contributions. Additionaly the transient surge motion of the moored body was simulated with including the roll of the time-memory effect. In this simulation the spring constant of the spread Turret mooring system is updated at every time step for considering the nonlinear effect.

• Journal of Advanced Marine Engineering and Technology
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• v.37 no.6
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• pp.644-652
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• 2013

This paper describes the development and field experiments of Manta-type Unmanned Underwater Vehicle (UUV). Various simulations for Manta UUV are performed by using the nonlinear 6-DOF motion of equations. Through this simulation we verified the motion performances of Manta UUV. To acquire the blueprint of Manta UUV, it was designed with the simulation results. The Manta UUV uses a Doppler Velocity Log (DVL), gyrocompass, GPS, pressure sensor and other minor sensors, applied to measure the motion, position and path of Manta UUV. For its propulsion and changing a direction in the underwater, one vertical fin and four horizontal fins are installed at the hull of UUV. The Manta UUV system was verified with motion and autonomous navigation test at field.

• Journal of Advanced Marine Engineering and Technology
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• v.34 no.6
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• pp.816-824
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• 2010

The forces applying to an object in the transferring pipe of waste are analyzed and the equation of motion is established in this paper. It is shown that the equation of motion becomes the 1st order non-linear differential equation. Using its general solution, the velocity of the object in the transferring pipe of waste can be expressed in the explicit form. Noting that the velocity of object is impact velocity to the elbow or curved part of the transferring pipe of waste, the kinetic energy of the object can be calculated and the necessary impact strength of inner wall is obtained. The velocity of object is also calculated and presented in the graphic forms with the condition of air velocity 30m/sec. The impact test of cast basalt tube is carried out by the free fall of a weight and the test results show that the impact strength of the cast basalt tube is sufficient to apply to protecting inner wall of the transferring pipe of waste.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.1
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• pp.21-28
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• 2010

This paper describes the mathematical model and controller design for Manta-type Unmanned Underwater Test Vehicle (MUUTV) with 6 DOF nonlinear dynamic equations. The mathematical model contains hydrodynamic forces and moments expressed in terms of a set of hydrodynamic coefficients which were obtained through the PMM (Planar Motion Mechanism) test. Based on the 6 DOF dynamic equations, numerical simulations have been performed to analyze the dynamic performances of the MUUTV. In addition, using the mathematical model PID and sliding mode controller are constructed for the diving and steering maneuver. Simulation results show that the control performances of the MUUTV and compared with these of NPS (Naval Postgraduate School) AUV II.

• Journal of Biomedical Engineering Research
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• v.20 no.3
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• pp.315-321
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• 1999

The purpose of this study is to develop a mathematical model for system identification in order to predIct muscle force based on eledromyographic signal. Therefore, a finding of the relalionship between characteristics of electromyographic signal and the corre spondng muscle force should be necessiiry through dynamic, joint model. To develop the dynamic joint model, the upper limb mcludmg the wrist and elbow joint has been considered. The kinematic and dynamic data, such as joint angular displacement, velocity, deceleration along with the moment of inertla, required to establish the dynamic model has been obtained by electrical flexible goniometer which has two degree-of-frcedoms. ln this model, muscle force can be predicted only electromyographs through the relationship between the integrated lorce and the mtegrated electromyographic signal over the duration of muscle contraclion in this study.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.9
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• pp.688-693
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• 2016

This paper describes the parachute dynamics modeling and simulation results for the development of training simulator of a HALO (High Altitude Low Opening) parachute, which is currently in use for military purposes. The target parachute is a rectangular shaped parafoil and its dynamic model is derived based on the real geometry data as the 9-DOF nonlinear equations of dynamics. The simulation was conducted through the moment of inertia and its aerodynamic derivatives to reflect the real characteristics based on the MATLAB/Simulink. In particular, its modeling includes the typical characteristics of the added mass and moment of inertia, which is shown in the strong effects in Lighter-Than-Air(LTA) flight vehicle. The proposed dynamic modeling was evaluated through the simulation under the spiral turning flight conditions of the asymmetric control inputs and compared with the performance index in the target parachute manual.

• The Journal of the Korea Contents Association
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• v.21 no.7
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• pp.477-487
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• 2021

Alternative education in Korea has grown into an educational movement since the 1990s. The alternative education is affecting and growing the public education system such as innovative schools, free semester systems, and high school credit systems. In 2021, an institutional foundation was also established to be recognized and supported as an educational institution. As a result of reflecting on the alternative education movement for 20 years, it is understood as stagnant lost time in the second half of the decade. It is discussing reorganizing the meaning of future-oriented "alternatives" with the new "alternatives". The poverty of educational philosophy has also been highlighted as an issue, but no special discussions have been underway. Thus, the study discussed to propose an educational philosophy that could capture the ideologies of alternative education. Critical pedagogy aims to foster human beings who are subjective, autonomous, active and self-reliant through conscious emancipation. In recent years, critical pedagogy have discussed ecological environment and feminism. The educational philosophy of scholars such as Freire and Illich was the basis of the early alternative educational movement. Considering this, the study discusses that Korea's alternative education movement can be understood through critical education and is reasonable as an educational philosophy for new alternatives in the future.

• The Journal of the Convergence on Culture Technology
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• v.9 no.5
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• pp.105-110
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• 2023

This article attempts to analyze John Greenleaf Whittier's anti-slavery poems. As a Quaker, he criticizes and satirizes the rife slavery in the mid nineteenth century. His thoughts are based on his religious belief. "The Farewell of a Virginia Slave Mother" depicts the mother who lost daughter for she was sold to the South. The harsh state of the corrupt South is described. In "Massachusettes to Virginia," the speaker, deploring the moral corruption of Virginia, denounces any attempt to return slaves to slave states. With a moonrise as a socio-political symbol, "Arisen at Last" celebrates the passage of law to protect fugitive slaves. Written after the Civil War, "The Peace Autumn" celebrates the peaceful situation in which Emancipation was declared. His efforts contributed to the abolitionist literature.