• Special Issue of the Society of Naval Architects of Korea
• /
• 2008.09a
• /
• pp.68-75
• /
• 2008

This paper describes the design and implementation of a low cost inertial navigation system(INS) using an inertial measurement unit(IMU), a digital compass, GPS, and an embedded system. The system has been developed for a transporter that load and unload ship blocks in a shipbuilding yard. When the transporter would move from place to place, they would periodically pass under obstructions that would obscure the GPS signal. This increases the error when estimating the position. Thus the INS has been used to improve position accuracy. INS is also capable of providing continuous estimates of the transporter's position and orientation. Even though IMU is typically very expensive, this INS is made of "low cost" components and the indirect Kalman filtering algorithm.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.19 no.2
• /
• pp.143-150
• /
• 2015

At present, the actual condition is that Korean modular structures are limited to a low rise detached house and military barracks. And there is no standardized structural design method of stacked modular structure. Accordingly, in general, they don't review impact force in the stage of stacking and installing a module, the effect which wind load has on a structure in the stage of lifting, and inertial force occurring in the stage of lifting or transporting a module in the process of constructing a structure. Therefore, this study investigated the construction method of modular system to be studied in stages, and decided on the position to which load was applied and boundary condition in structural analysis at each construction stage. Besides, inertial force according to each speed was calculated in the lifting and wheeled transport of module. And we calculated impact load according to lifting speed in module stacking and installation work and wind load due to instantaneous wind speed in the installation work by lifting. On the basis of the suggested method, in the modular system to be studied, it carried out review of structure by changing determining conditions of load being applied by construction stage, such as in the stage of lifting, in the stage of transport, and in the stage of installation, and drew construction conditions securing stability structurally.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.38 no.7
• /
• pp.647-654
• /
• 2010

In this study, an efficient ornithopter aerodynamic model, which is applicable to ornithopter wing design considering fluid-structure interaction or ornithopter flight dynamics and control simulation, was proposed and experimentally validated through the wind tunnel experiments. Due to the ornithopter aerodynamics governed by unsteady low Reynolds number flow, an experimental device was specially designed and developed. A part of the experimental device, 2-axis loadcell, was situated in the non-inertial frame; the dynamic calibration method was established to compensate the inertial load for pure aerodynamic load measurements. The characteristics of proposed aerodynamic model were compared with the experimental data in terms of mean and root-mean-square values of lift and drag coefficients with respect to the flow speed, flapping frequency, and fixed angle of attack.

• Transactions of the Korean Society of Machine Tool Engineers
• /
• v.13 no.4
• /
• pp.64-72
• /
• 2004

In this paper, the dynamic stability of a hydraulic excavator using ZMP concept is considered. When a load is moved in an excavator based on automation, an excavator often loses the stability and falls over. This is because a dynamic element is not included in the moment equilibrium equation that is used in order to judge a reversal. Consequently, reversal distinction algorithm including all a static and a dynamic element along a load movement in crane work is necessary. Zero Moment Point(ZMP) is a point on the floor where the resultant moment of the gravity, the inertial force of the manipulator and the external force is zero. This study is going to interpret the reversal stability of the excavator to which is applied ZMP concept through simulation.

• International Journal of Railway
• /
• v.3 no.1
• /
• pp.1-6
• /
• 2010

The steel plate-girder bridges with concrete gravity piers have possibilities of overturning by lateral inertial force which can be reproduced by sudden earthquake attack. This paper explores an overturning mechanism of existing concrete gravity pier onto the sandy soil in the event of lateral push-over load by in-situ experimental observation. The in-situ push-over experiment for pier with earth anchors between spread footing and rock beds exhibits a reasonable enhancement of ductility against overturning. In unanchored system, a flexural crack at cold joint of concrete pier is not developed because of the over-turning of the pier. This leads a global instability (rotation) of pier-footing system with relatively low stresses in pier itself. While a lateral load is persistently increased in anchored system, the successive flexural cracking failure at cold joint is observed even after the local shear failure of soil due to redistribution of stress equilibrium between soil and pier structure as long as a tensile action of anchor cable is active.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.50 no.7
• /
• pp.507-514
• /
• 2022

The EO/IR targeting pod mounted on a fighter to acquire information about tactical targets is typically mounted and operated at the bottom of the aircraft fuselage. Since the aircraft equipped with such an external attachment has complexed aerodynamic and inertial characteristics compared to the aircraft flying without an external attachment, a method of system performance analyses is required to identify development risk factors in the early stages of development and reflect them in the design. In this study, a development plan was presented to provide the necessary modeling and simulation tools to develop a pod that can acquire measurement data stably in a highly maneuverable environment. The limiting operating conditions of the pods mounted on the highly maneuverable aircraft were derived, the aerodynamics and inertial loads of the mounted pods were analyzed according to the limiting operating conditions, and a flight data generation and transmission system were developed by simulating the mission of the aircraft equipped with the mounted pods.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.33 no.5
• /
• pp.34-40
• /
• 2005

Most analyses and researches on Micro Aerial Vehicle(MAV) have focused upon propulsion, automatic control, aerodynamic configuration in low Reynolds number region, and miniaturization of telemetric parts. In the present study, a structural concept for MAV is designed by using the composite material suitable for light flight structures. In order to study the load path and stress state of the MAV, the load and structural analyses are simultaneously performed by the aeroelasticity module of MSC/NASTRAN. The stability derivatives of the MAV are obtained for three symmetric, two antisymmetric, and four unsymmetric maneuvering conditions. Although the aerodynamic theory in MSC/NASTRAN could not be proper for MAV analysis, it provides an traditional and effective tool for trim and load analyses and may be corrected with the results by more accurate theory or test. The results show that the inertial load due to payloads has a more effect on stress rather than the aerodynamic load.

• Wind and Structures
• /
• v.20 no.5
• /
• pp.609-622
• /
• 2015

This study presents a dynamic response analysis of operational and parked wind turbines in order to gain better understanding of the roles of wind loads on turbine blades and tower in the generation of turbine response. The results show that the wind load on the tower has a negligible effect on the blade responses of both operational and parked turbines. Its effect on the tower response is also negligible for operational turbine, but is significant for parked turbine. The tower extreme responses due to the wind loads on blades and tower of parked turbine can be estimated separately and then combined for the estimation of total tower extreme response. In current wind turbine design practice, the tower extreme response due to the wind loads on blades is often represented as a static response under an equivalent static load in terms of a concentrated force and a moment at the tower top. This study presents an improved equivalent static load model with additional distributed inertial force on tower, and introduces the square-root-of-sum-square combination rule, which is shown to provide a better prediction of tower extreme response.

• Journal of Korean Society of Steel Construction
• /
• v.18 no.5
• /
• pp.535-542
• /
• 2006

In this study, the effects of cross beams on the lateral distribution of live loads in composite rolled H-beam girder bridges, were investigated through three-dimensional finite element analysis. The parameters considered in this study were the inertial moment ratio between the main girder and the cross beam, the presence of the cross beam, and the number of cross beams. The live load lateral distribution factors were investigated through finite element analysis and the customary grid method. The results show that there was no difference between the bridge models with and without a cross beam. The cross beam of the beam and frame types also showed almost the same live load lateral distribution factors. However, the finite element analysis showed that the concrete slab deck plays a major role in the lateral distribution of a live load, and consequently, the effect of the cross beam is not so insignificant that it can be neglected.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.14 no.2
• /
• pp.822-827
• /
• 2013

In this paper, how to stop a moment to experiment with stop function, electric brake type scale model propulsion system is designed and fabricated by control of the braking torque is proposed. Scale model system for motor-driven, inertial load, the structure of the load for the motor and the inverter system was constructed with two sets of converters, the actual range of the rotational speed of the vehicle DDM experiments to be able to. In Additional, observer to estimate the rotor position and speed of using resolver, and the pole at low speed, speed detection methods have been developed. As a result of this study, first, stop the moment Second, the reduction of braking torque, and how to initiate the operation of the air brake blending by using the braking, improve braking methods that only use the electric brake to stop brought.