• Journal of the Korean Society of Safety
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• v.9 no.1
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• pp.146-154
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• 1994

A series of numerical calculations are performed in order to investigate the dispersion mechanism of toxic gaseous and solid pollutants in extremely short-term and short range. The calculations are carried out in an open space characterized by turbulent boundary layer. The simulation is made by the use of numerical model, in which a control-volume based finite difference method is used together with the SIMPLEC algorithm for the resolution of the pressure-velocity coupling problem. The Reynolds stresses are solved by two-equation, k-$\varepsilon$ model modified for buoyancy. The major parameters consider-ed in this study are temperature, velocity and Injection height of toxic gases, environmental conditions such as temperature and velocity of free stream air, and topographic factor. The results are presented and discussed in detail. The flow field is commonly characterized by the formation of a strong recirculation zone due to the upward motion of the hot toxic gas and ground shear stress. The driving force of the upward motion is explained by the effect of thermal buoyancy of hot gas and the difference of inlet velocity between toxic gas and free stream.

• Proceedings of the KIEE Conference
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• 2006.10c
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• pp.172-174
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• 2006

In this paper, we propose the trajectory generation method for bipedal walking on the stairs. This method is based on multi-masses inverted pendulum mode (MMIPM). MMIPM can effectively reduce the ZMP error but it is only applied to walking on the flat ground. In order to reduce ZMP error when a robot walks on the stairs, we generate the walking motion by MMIPM and modify that motion using parametric functions. We determine the values of the parameters by the simulations. Simulation results show that the robot can walk more stable on the stairs.

• 제어로봇시스템학회:학술대회논문집
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• 1992.10a
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• pp.959-964
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• 1992

This study treats the method for kinematic modeling of the biped walking robot, for synthesizing various gait trajectories, and for calculating adequate values of the joint torque inside the stable region. To synthesize various and anthropomorphic walking easily, the gait trajectory is specified by a set of ten walking prameters, and the trunk motion equation is derived by the zero moment point and the gait trajectory. By distributing ground reaction force and moment reduced at the zero moment point to the both feet, the joint torque equation can be derived readily, and according to this equation, the joint torque to stable walking can be computed.

• Proceedings of the KIEE Conference
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• 2004.05a
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• pp.138-140
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• 2004

This paper mainly deals with the dynamic walking of a biped robot. At first, in order to walk in various environments, it is desirable to adapt to such ground conditions with a suitable foot motion, and maintain the stability of the robot by a smooth hip motion. A method to plan a walking pattern consisting of a foot trajectory and a hip trajectory is presented. The effectiveness of the proposed method is illustrated by simulation results. Secondly, the paper brings forward a balance control technique based on off-line walking pattern with real-time modification. At last, the concept of Zero Moment Point (ZMP) is used to evaluate dynamic stability.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.04a
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• pp.388-392
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• 1996

Orbit Determination is process of obtaining values of those parameter which completely specify the motion of an orbiting body through space, based on a set of observation of the body. For the narrow land of Korea, the ground tracking system has very limited time of operation. In this connection the use of GPS for orbit determination has advantage of full autonomy on the ground station. It would be more powerful economical method for near-earth satellites. Therfore we have better to pay attention to the research of satellites of orbit determination by use of GPS. So in this research, we studied themotion of the satellites with estimation using GPS. As a result, the result of computer simulation show that good convergence and indicated effective for real operation.

• Journal of Institute of Control, Robotics and Systems
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• v.18 no.3
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• pp.251-257
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• 2012

Unmanned ground vehicles have important military, reconnaissance, and materials handling application. Many of these applications require the UGVs to move at high speeds through uneven, natural terrain with various compositions and physical parameters. This paper presents a framework for high speed autonomous navigation based on the integrated real time traversability. Specifically, the proposed system performs real-time dynamic simulation and calculate maximum traversing velocity guaranteeing safe motion over rough terrain. The architecture of autonomous navigation is firstly presented for high-speed autonomous navigation. Then, the integrated real time traversability, which is composed of initial velocity profiling step, dynamic analysis step, road classification step and stable velocity profiling step, is introduced. Experimental results are presented that demonstrate the method for a $6{\times}6$ autonomous vehicle moving on flat terrain with bump.

• Proceeding of EDISON Challenge
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• 2016.03a
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• pp.473-476
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• 2016

In this study, important design factors in Jansen leg mechanism by which two legs can be driven by only one input like a motor are considered through method of transmitting motion in three-bar linkage and Grashof law in four-bar linkage. In preliminary design, by using EDISON m-sketch and its simulation which can observe trace of feet, two identical four-bar linkages are initially designed and two three-bar linkages are added to four-bar linkages sequentially. By analyzing GL(Ground Length) and GAC(Ground Angle Coefficient), the adequacy of the preliminary design was estimated. Final design of walking apparatus is implemented using CAD software, Assembly2 of EDISON Designer. Finally, proposals to improve software used in this study are suggested.

• Proceeding of EDISON Challenge
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• 2016.03a
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• pp.506-509
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• 2016

In this paper, the multi-leg robot is designed using Teo Jansen mechanism. The purpose of this paper is to develop unique robot, which operates efficiently in any environment. In that case, speed and accuracy are required. The indication which evaluate the value is Ground Score according to the Jansen's mechanism. To optimize the Ground Score. Genetic Algorithm (GA) in MATLAB Toolbox is used, which is numerical analytic algorithm to quickly convergence into optimum point. The Optimization of value is visualized by M-Sketch. M-Sketch was useful for simulation and evaluation of mechanic's dynamic motion. The robot's draft is produced into finished product by Edison Designer.

• Journal of Korea Water Resources Association
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• v.53 no.9
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• pp.661-670
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• 2020

The water supply system has a wider installation range and various components of it than other infrastructure, making it difficult to secure stability against earthquakes. Therefore, it is necessary to develop methods for evaluating the seismic performance of water supply systems. Ground Motion Prediction Equation (GMPE) is used to evaluate the seismic performance (e.g, failure probability) for water supply facilities such as pump, water tank, and pipes. GMPE is calculated considering the independent variables such as the magnitude of the earthquake and the ground motion such as PGV (Peak Ground Velocity) and PGA (Peak Ground Acceleration). Since the large magnitude earthquake data has not accumulated much to date in Korea, this study tried to select a suitable GMPE for the domestic earthquake simulation by using the earthquake data measured in Korea. To this end, GMPE formula is calculated based on the existing domestic earthquake and presented the results. In the future, it is expected that the evaluation will be more appropriate if the determined GMPE is used when evaluating the seismic performance of domestic waterworks. Appropriate GMPE can be directly used to evaluate hydraulic seismic performance of water supply networks. In other words, it is possible to quantify the damage rate of a pipeline during an earthquake through linkage with the pipe failure probability model, and it is possible to derive more reasonable results when estimating the water outage or low-pressure area due to pipe damages. Finally, the quantifying result of the seismic performance can be used as a design criteria for preparing an optimal restoration plan and proactive seismic design of pipe networks to minimize the damage in the event of an earthquake.

• Steel and Composite Structures
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• v.20 no.2
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• pp.317-335
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• 2016

Concentrically braced steel frames (CBFs) can be optimised during the seismic design process by using lateral loading distributions derived from the concept of uniform damage distribution. However, it is not known how such structures are affected by uncertainties. This study aims to quantify and manage the effects of structural and ground-motion uncertainty on the seismic performance of optimum and conventionally designed CBFs. Extensive nonlinear dynamic analyses are performed on 5, 10 and 15-storey frames to investigate the effects of storey shear-strength and damping ratio uncertainties by using the Monte Carlo simulation method. For typical uncertainties in conventional steel frames, optimum design frames always exhibit considerably less inter-storey drift and cumulative damage compared to frames designed based on IBC-2012. However, it is noted that optimum structures are in general more sensitive to the random variation of storey shear-strength. It is shown that up to 50% variation in damping ratio does not affect the seismic performance of the optimum design frames compared to their code-based counterparts. Finally, the results indicate that the ground-motion uncertainty can be efficiently managed by optimizing CBFs based on the average of a set of synthetic earthquakes representing a design spectrum. Compared to code-based design structures, CBFs designed with the proposed average patterns exhibit up to 54% less maximum inter-storey drift and 73% less cumulative damage under design earthquakes. It is concluded that the optimisation procedure presented is reliable and should improve the seismic performance of CBFs.