• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.37 no.5
• /
• pp.641-648
• /
• 2013

A beam is a major load-carrying member in many engineering structures. Beams with properly designed cross sections and stiffeners are required to enhance the structural properties. Such a design may cause various coupling behaviors, and therefore, an accurate analysis is essential for the proper design of beams. In this research, we manufactured box-beams with stiffeners, which mimic the out-of-plane composite bending-shear coupling behavior reported in literature. A modal test is carried out to obtain the dynamic characteristics, such as natural frequencies and mode shapes, of the box-beam. The obtained results are compared with those of 3D FEM, which confirm that the out-of-plane bending-shear coupling behavior reported in literature is possible. The coupling behavior can be controlled by the proper design of the stiffeners.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2011.11a
• /
• pp.213-217
• /
• 2011

Unsteady numerical simulations of pintle nozzles were implemented for solid rocket thrust vector control. The variation of pintle location was considered using unsteady numerical techniques, and dynamic characteristics of various pintle models were investigated. In order to consider the variation of the pintle location, a moving mesh method was applied. The effects of shape and location of the pintle nozzle have been analytically investigated. And the results were compared with numerical results. The chamber pressure, mass flow and thrust are analyzed to take account dynamic characteristics of pintle performance.

• Journal of the Korean earth science society
• /
• v.30 no.3
• /
• pp.294-304
• /
• 2009

A statistical prediction model for the typhoon intensity and track in the Northwestern Pacific area was developed based on the artificial neural network scheme. Specifically, this model is focused on the 5-day prediction after tropical cyclone genesis, and used the CLIPPER parameters (genesis location, intensity, and date), dynamic parameters (vertical wind shear between 200 and 850hPa, upper-level divergence, and lower-level relative vorticity), and thermal parameters (upper-level equivalent potential temperature, ENSO, 200-hPa air temperature, mid-level relative humidity). Based on the characteristics of predictors, a total of seven artificial neural network models were developed. The best one was the case that combined the CLIPPER parameters and thermal parameters. This case showed higher predictability during the summer season than the winter season, and the forecast error also depended on the location: The intensity error rate increases when the genesis location moves to Southeastern area and the track error increases when it moves to Northwestern area. Comparing the predictability with the multiple linear regression model, the artificial neural network model showed better performance.

• Journal of Broadcast Engineering
• /
• v.16 no.3
• /
• pp.448-461
• /
• 2011

H.264/AVC significantly outperforms the previous video coding standards with many new coding tools. Among these tools, several intra-block coding tools can particularly improve coding efficiency. For intra prediction, H.264/AVC supports most probable mode in the entropy coding process to reduce syntax elements indicating intra prediction modes and most probable mode selection ratio is very high. Also, in general, natural images and videos have many homogeneous regions whose high correlation with neighbouring blocks. In this paper, we propose intra prediction mode SKIP mode using decoder-side prediction to improve the coding efficiency. The proposed method is determined the optimal prediction mode using only neighbouring block's information and coded on the basis of the conventional prediction/transform coding. And the prediction modes are not send to decoder at all. Skipped intra prediction mode is determined by decoder. Experimental results show that the proposed method achieves coding gains of 1.40% for common intermediate format(CIF), 3.24% for 720p sequences against the H.264/AVC JM 17.0 reference software.

• Nuclear Engineering and Technology
• /
• v.27 no.6
• /
• pp.833-844
• /
• 1995

In self-tuning predictive control algorithm for steam generator is presented. The control algorithm is derived by suitably modifying the generalized predictive control algorithm. The main feature of the unposed method relies on considering the measurable disturbance and a simple adaptive scheme for obtaining the controller gain when the parameters of the plant are unknown. This feature makes the proposed approach particularly appealing for water level control of steam generator when measurable disturbance is used. In order to evaluate the performance of the proposed algorithm, computer simulations are done for an PWR steam generator model. Simulation result show satisfactory performances against load variations and steam flow rate estimation errors. It can be also observed that the proposed algorithm exhibit better responses than a conventional PI controller.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.31 no.10
• /
• pp.40-50
• /
• 2003

The operational orbit evolution of the KOMPSAT-l over 3 years was analyzed. During LEOP, four orbit maneuvers were performed to obtain the optimized orbit and eight safe-hold modes happened. The effects of unpredictable occurrence of the safe-hold mode and the highest solar activity on the orbit evolution during the mission life were analyzed. The comparison of orbital elements between long-term predicted orbit and determined orbit from observed data was also performed. The operational orbit started from the optimized one was evolved within the boundary of the designed mission orbit except altitude and it was verified the sun-synchronous orbit was successfully maintained.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.41 no.4
• /
• pp.271-277
• /
• 2017

In this paper, the amplitude and frequency dependent dynamic characteristics of the equivalent stiffness of a rubber bushing are investigated. A new mathematical model is proposed to explain the large deformation and size effect of a rubber bushing. The proposed model consists of elastic, viscous, and frictional stress components and the equivalent strain. The proposed model is verified using experimental results. The comparison shows that the proposed model can accurately predict the equivalent stiffness values of a rubber bushing under various magnitudes and frequencies. The developed model could be used to predict the dynamic equivalent stiffness of a rubber bushing in automotive engineering.

• Journal of the Korean Institute of Intelligent Systems
• /
• v.16 no.5
• /
• pp.601-607
• /
• 2006

This paper proposes a novel balance control scheme of a biped robot to predict the next position of ZMP using Kalman Filter. The mathematical model of the biped robot is generally approximated by 3D-LIPM(3D-Linear Inverted Pendulum Mode), but it cannot completely express the robot's dynamics. The stability of the biped robot depends on whether the ZMP(Zero Moment Point) position is in the stability region or out of. And the internal error between the robot mechanism and its model could affect the stability of a robot. Therefore, the proposed balance control not reduces the internal error, but also timely generates the proper control. The experiment of the proposed balance control is simulated on the virtual workspace where the biped robot may encounter with various difficulties.

• Nuclear Engineering and Technology
• /
• v.27 no.6
• /
• pp.853-858
• /
• 1995

The initial condition of a core transient should be consistent with real core state for the simulation of the core tansient. The initial xenon distribution, which can not be measured in the core, has a significant effect on the transient with xenon dynamics. In the simulation of the transient starting from non-equilibrium xenon state, the accurate initialization of the non-equilibrium xenon distribution is essential for the prediction of the core transient behavior. In this study, a xenon initialization method to predict the core transient more accurately was developed through the equivalent pre-xenon-oscillation which represents the tenon oscillation before the transient and verified by the application of the simulation for a startup test of Yonggwang Unit 3.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.11 no.5
• /
• pp.1791-1798
• /
• 2010

This research predicted the change and characteristics of space structure by new residential area development through objective and quantitative analysis of urban spatial configuration using space syntax and associated the prediction with the city status statistics data and quantitative analysis, and the results are summarized as follows: (1) If large scale new residential area of Dongnae township proceeds to be developed according to present plan, accessibility to the new residential area will drop, and also as the outside space ripple effects by new residential area development also are anticipated small, the new residential area apprehensibly will not succeed to play the role of integrating the entire city structurally, but will cause structural problem, severing the city structure. (2) If the city planned road between existing urban center planned based on 2004 Chuncheon city plan overall drawing and main road which is the entrance road of the planned new residential area is developed together, the accessibility to the entire space of Chuncheon city and the new residential area will be easy, allowing the new residential area properly integrated into the entire space of Chuncheon city, consequently giving a prediction that classification of land use between the central part of Chuncheon city and surrounding residential area would become conspicuous.