Three-dimensional motion analysis systems and force plates are used for gait phase detection and ground reaction force(GRF) or ground reaction moment(GRM) data collection. But force plates as measurement systems are restricted to laboratory environments and have limitations for abnormal walking with foot dragging. Therefore the methods were proposed to compute the GRM from the kinematic data of three-dimensional motion analysis systems. Gait phase detection with kinematic data using foot velocity algorithm(FVA) was performed. The validity of gait phase detection was obtained comparing with the results of force plates. A gait model with 7 segments was composed to compute GRM. The results of gait model with kinematic data were compared with those of force plates. The result of the vertical direction is similar. But anterior-posterior direction and lateral direction show similar tendency with some gaps.
The limitations and problems of the rechargeable battery and short mileage per one electric charging have not been overcome at the electric vehicles. To solve these problems, the hybrid vehicle has been developed by securing the performance of automotive with the conventional internal combustion engine and the environmental benefit. Meanwhile, the electric UTV (utility terrain vehicle) which has this environmental benefit has been widely used for factories, parks, leisure and agricultural areas. In this study, the electric UTV was fabricated and attached the auxiliary power drive systems including the photovoltaic power generation system into this electric vehicle in order to make up the hybrid (motor + photovoltaic) vehicle system. As the range of the hybrid UTV would be extended over 20% than that of the existing golf cart per one electric charging through this successful development, the dynamic stiffness was improved through light-weight body design.
In this study, factors analysis is performed for reducing friction in elevation motion of a large television stand over 50-inch. The first is a pipe type cross-section control for accurate position control of the piston rod. Here, it was compared with the pipe type and labyrinth type orifice cross-section. The second study attempted to reduce the frictional force the gas seal lip technology. As the result of the first study, in the orifice cross section study between pipe type and labyrinth type through CAE and experimental consideration, cross section of labyrinth type orifice is preferred for reducing of friction. As the result of the second study, in the gas seal lip technology, the outer-inner diameter of φ20×φ8 in the test result of hollow rod is revealed more proper if the weight of 50 inch television assumed as 30kgf.
Mechanical fatigue tests which consist of an alternate load and compression cycle show that droppers for 400km/h operation have cyclic mechanical strength of 300N with compression amplitude 0.05m. Numerical simulations for forces on the dropper during the passage of a train tell that dynamic forces can be varied up to 15% due to installation tolerance. Taking into account of the 15% variation, we end up with the maximum allowable peak load of 260N for the dropper. Peak value of measured forces on the dropper at the speed of 400km/h is 152N, which is less than the maximum allowable peak load of 260N. Conclusively, the possibility of fatigue fracture for the dropper is quite low.
In this study, the curvature FSW experiments were performed with the 2 mm thickness of Al 5083-O using by the 5 axis(X/Y/Z/A/C) position control system. For the mechanical test of the butt joints, the tungsten heavy alloy as the tool material without necessary after finishing the heat treatment such as quenching was used. In particular, the insertion depth and the welding speed was changed at the constant rotation speed in order to select the optimum FSW condition. The test results were visually satisfactory for the approximate joint length of 300 mm. Sound joint was formed at the condition of 1.9 mm-1000 rpm-100 mm/min and its tensile strength of joint was the most high almost the same as that of the base material.
The objective of this study is to evaluate the structural safety of the spherical-helical turbine for hydro-power. We analyze fluid-structure interaction of the spherical-helical turbine for hydro-power using ANSYS-CFX and Mechanical. The maximum combined stress, deformation and safety factor of the spherical-helical turbine in cases of three types of materials were obtained by fluid-structural analysis. From structural analysis, the maximum value of the equivalent stress occurred at the shaft of the turbine for three material types. In case of a polyethylene turbine blades, the maximum equivalent stress and safety factor were 3.46 MPa and 7.23. Polyethylene turbine blades were evaluated to be safe except of the turbine shaft. Several researches will be performed based on the results of this study and more research and development of technologies are needed in this field.
To overcome recent emission regulation, various hybrid systems are being developed. In the E-4WD(electric four wheel drive) system, the engine and transmission drive the front wheel, electric motor and single reduction gear drive the rear wheel. As the gear ratio of the reduction gear set determines the electric motor's operating point, the gear ratio is important to enhancement efficiency of hybrid system. This study is to analyze motor reduction gear ratio's influence on E-4WD hybrid system for optimized efficiency and driving performance. Fuel economy, operating point of power source and hybrid mode are analyzed using simulation developed with dynamic programming method.
The vehicle weight and alternative light materials development like aluminum alloys are hot issues around the world. In order to obtain the goal of the weight reduction of automobiles, the researches about lighter and stronger suspension links have been studies without sacrificing the safety of automotive components. Therefore, in present study, the structure analysis of the torque strut links made by aluminum alloys (A356) was performed by using CAE (computer aided engineering) to investigate the light weight design process from the reference of the rear suspension torque strut link which was made by STKM11A steel and was already proven in the commercial market. Especially, the simulated maximum von Mises stresses after strength analysis were normalized as fatigue limit and these were converted to the WF (weight factor) of the same type as the fatigue safety factor suggested and named like that in present study. From these, it was suggested that the fatigue properties of the torque strut could be simply predicted only from this static CAE simulation.
Aircraft simulators are very useful tools to study aircraft behaviour and to develop flight control systems. Nowadays, these simulators are used for UAV's development. In this paper, a PC-based aircraft simulator system is developed by the LabVIEW software. It consists of a simulation program run on a computer, an input stick, and a control surface. The simulation program calculates aircraft dynamics and displays aircraft motion by a 3D graphic object. The program measures the movement of the input stick and rotates the control surface as commanded. The simulator system has been demonstrated by several simulation tests. The system will be used for UAV development.
The characteristics of the turbulent MHD channel flows are analysed within the elliptic blending model. The evaluation of additional terms representing the MDH interactions in the transport equation for the turbulent kinetic energy and dissipation rate is carried out firstly. And then, the improvement of model coefficients for the additional terms is achieved. Regardless of the magnetic field orientation, perpendicular and parrel to the main flow, the model coefficients for the additional terms are not changed to maintain the generality of the present model. The prediction results are directly compared to the DNS data to assess the performance of the present model.
In order to provide the basis data for broad use and safe design of carbon fiber reinforced plastic, this paper aims at investigating the fracture behavior on CFRP specimen composed of one directional fiber through three point bending test. On the basis of experimental result, the improvement of composite layer specimen can be secured with the other data to compare the existing specimen. The fracture behavior happened at the experimental procedure is investigated in this study. The maximum loads of 1200 N, 1700N and 1600N are shown respectively at the specimens with the layer angles of 30°, 45° and 60°. The highest load is shown at the layer angle of 60° among all specimens and the longest displacement is maintained until each of the layer structure is broken down. The fracture due to the force applied from the outside can be prevented by applying the result of this study to the real structure. As structural safety can be evaluated and anticipated through this study, it is thought that the safe design is devoted.
In this study, factors analysis is performed for reducing friction in elevation motion of a large television stand over 50-inch. The first is a pipe type cross-section control for accurate position control of the piston rod. Here it was compared with the pipe type and labyrinth type orifice cross-section. The second study is for specification decision and volume compensation experiment as an apparatus for compensating of the volume of the cylinder is compressed as the volume of piston rod. Consequently, in the orifice cross section study between pipe type and labyrinth type through CAE and experimental consideration, cross section of labyrinth type orifice is preferred for reducing of friction. The result of total consideration in stability problem and performance of volume compensation for specification decision and volume compensation experiment is determined the final speculation of hollow rod φ8×φ4 and riveting system.
Homogeneous liquid crystal (LC) alignment on hafnium strontium oxide (HfSrO) films prepared by sol-gel process via ion-beam (IB) bombardment was investigated. Uniform LC alignment was achieved on the IB-irradiated HfSrO films at IB intensity of 1.8 keV. We confirmed the effect of surface morphology on LC alignment using field-emission scanning electron microscope (FE-SEM). In addition, we observed electro-optical characteristics of the twisted-nematic (TN)-LC cells based on HfSrO films to verify the possibility of LC display (LCD) application.
Recently, car industry trend is downsizing, a lean-burn engine, green car and cost cutting. A turbocharger is the key components to improve fuel efficiency and power. This research is to study on the flow analysis in the performance analysis for change rotating speed of turbocharger turbine with three different rotating speed in the turbine. After measuring real design features, modeling, velocity distribution, pressure distribution and temperature distribution are conducted numerically. Torque and power are compared with three different cases in order to analyze the performance for turbine. Finally, optimum power is determined with the sequence of case 1, case 2, and case 3.
One of the important advantages of Thermosonics is that it can be applied to complex structures such as a turbine blade as a convenient and quick screening test method. For a reliable thermosonic test, the vibrational characteristics of the system comprising the tested structure and the clamp at ultrasonic frequency range should be identified. Therefore, this study presented the analysis results of frequency response functions and mode shapes of the turbine blade and clamp system and investigate the possibility of the reliable excitation system for the thermosonic test.
When working on electrical wiring and cable, Electrically insulated aerial work platforms must be used to prevent the electrocution hazards. Aerial work platforms with composition boom is able to increase the weight and height of the workspace due to the lightweight of boom. The aim of this paper is to clarify structural stability of 3 stage telescopic booms having an operator platform and an upper boom of composition(Fiber Reinforced Plastic) by comparing the general telescopic booms with steel material using computational analysis.
The performance of organic Rankine cycle was numerically investigated to recover heat from the exhaust of a heavy-duty diesel engine. Exhaust flow rates and temperatures are obtained from the simulation of diesel cycle by using GT-Power. The net power outputs of organic Rankine cycle for 9 working fluids were calculated by cycle simulations. The results showed that as for the net power outputs and the pressure of working fluids, R21 and R245fa are suitable as working fluids for ORC in diesel engine.
Composite materials have the strong durability and light weight as inhomogeneous material. These material are manufactured by combining and maximizing the advantage of each material. Among these various materials,
stainless steel, aluminum and brass has been used generally. Prior to using, the preparatory experiments are demanded in order to obtain the material strengths. In this study, the tensile tests are carried out with the specimens of stainless steel, aluminum and brass. These tensile specimens of same standards are made with the
notches at both sides of specimen. When the forced displacement of about 11 mm proceeds in case of stainless steel specimen, the maximum load of 31000 N is shown simultaneously with the fracture of specimen. When the forced displacement of about 6 mm proceeds in case of aluminum specimen, the maximum load of 20600 N is shown simultaneously with the fracture of specimen. When the forced displacement of about 7 mm proceeds in case of brass specimen, the maximum load of 25000 N is shown. In this study, the finite element analysis as ANSYS program is carried out in order to verify these experimental results. The experimental and analysis results are similarly shown each other. Through the result of this study, the analysis data with no experiments are thought to be trustworthy as the tensile experimental data.
The effect of gasoline-ethanol blends on performance and NOx emission was investigated in a SI engine with port and direct fuel injection systems. The 1-D cycle simulation program of GT-Power was utilized to analyze the performance of thermodynamic cycle. The results showed that the brake torques are increased with the addition of ethanol to gasoline because of the improvements of volumetric efficiency. The engine with direct ethanol blends injection system has more power than that with port gaoline injection system, which is caused by the higher latent heat of ethanol.
In this study, we analysed the influence of the flow and performance of the generated micro gas turbine with different rotational speeds. CFD analysis was also performed using commercial code called ANSYS CFX 14.5. It adopted the turbine of radial flow type suitable for power generation for small rotating equipment. The number of blades was designed with each radial turbine 8, vane nozzle 14. The boundary layer flow analysis was widely used to the SST model. Mass flow rate of the turbine was 1.45 kg/s. While the rpm varies from 38,000rpm to 48,000rpm under various boundary conditions, the distributions of Mach number and pressure were numerically analyzed for electric power output, turbine isentropic efficiency. We analyze the inlet pressure, outlet temperature, electric power output, turbine isentropic efficiency. It compared maximum and minimum revolution through CFD analysis. Power output of maximum revolution has been increased 18% more than minimum revolution. Isentropic efficiency of maximum revolution has been increased 16.5% more than minimum revolution. Therefore, maximum power output was 332kW, amaximum isentropic efficiency was 33.2%.