‘In structural system, a certain amount of uncertainties always persists in material properties, geometric parameters and applied loads. In this study, the structure is designed to withstand the uncertainties which are caused by either measurement inaccuracy or system complexity. Random structures are modelled by using ANSYS probabilistic design module. It can be applied easily to any structural system with random parameters. The aim of this paper is to make optimal design for the beam with random input variables due to width and height and response parameters due to displacements and stresses. The probabilistic design is also carried out with ANSYS APDL and then the optimal design is sequentially solved. As the total volume of beam, stresses and displacements at the beam are treated as random parameters, the numerical results are obtained.'
Recently, there are a lot of fires breaking out at special structures. To suppress this fire break down at early stage is very important because it leads to bigger damage in case of special structures. For early suppression, outer wall of building has to be destroyed and need waterproofing for Ignition temperature. So far there is no equipment developed local and all of them are imported from a broad. In this study, In this study, The CAE analysis was the Leading-in of the boom conditions for the development of demolition fire according to the environment of Korea. As a result of this, could be confirmed that decreases stress reduction. maximum 51% to 12% depending on the part. It was possible structural integrity and design. about Telescopic Boom and Outrigger on the basis of this result.
The proposed cone type CVT(Continuously variable transmission) is consisted of drive pulley, belt, belt move equipment, tensioner, belt guide and driven pulley. In this study, the function and the relationship of all parts in the cone type CVT were investigated. The speed ratio of cone type CVT at case in parallel and incline movement of belt was analyzed. Proposed cone type CVT can apply to electrical vehicle, scooter and golf cart etc..
The author introduces a test platform system that has been developed for variable-speed control moment gyroscopes(VCMGs). VCMGs are important actuators for spacecraft attitude control. The test platform consists of two VCMGs driven by servo motors and sensor modules. The control program has been coded by the NI LabVIEW. Accelerometers and gyros have been used to measure the attitude angle and angular speed of the platform. The 2nd order low pass filters have effectively filtered out noises from measurements. Wheel speeds and gimbal angles have been controlled satisfactory by PI control. Through some tests, moment generation has been verified. The moment has been generated as commanded. However, friction effect by a ball bearing, that supports the platform’s rotation, has been not negligible. As further studies, friction reduction will be studied. In conclusion, this test platform will be used for engineering education and research.
In recent years, there was many conflagration about special structure such as wooden cultural assets, warehouses and factories. The common causes of increase in the fire damage were difficulty of the initial suppression and absence of equipment for appropriate disaster prevention. In this study, the destruction-spray nozzles, a core technology of destruction-spray fire vehicle which is possible for fire suppression of special structure was studied using the finite element method. As a result, the maximum deviation of the part nozzle was 18.1% compared with the reference value. Second, the maximum deviation of the nozzle module was 13.5% compared with the part nozzle. Third, the safety factor about internal pressure of the nozzle module was suitable as 13.6. Finally, the performance of the designed destruction-spray nozzle was satisfied with 4,652.1L/min in excess of the target performance.
In this study, the weldability of ADC12 FSW joints obtained by the load control type of the FSW machine is examined. The higher the tool plunge downforce the wider the range of the optimum FSW conditions is obtained. However, there is a limit of optimum range with increasing the tool plunge downforces. The three different types of defects are formed in ADC12 FSW joints, depending on the welding conditions. One is a large mass of flash due to the excess heat input, another is a cavity or groove-like defects caused by insufficient heat input and the other is a cavity caused by the abnormal stirring. As for the abnormal stirring, it is very clearly seen that the shape of the top part on the advancing side in the stir zone is completely different. For this type of defect, the effect of the tool plunge downforce is not significant, though the size of the defect due to insufficient heat input significantly is decreased with the increasing downforce
In GMAW welding used mostly at the scene of a welding industry, welders can not see control panels in internal welds of vehicles and tanks, and can not adjust the current and voltage properly during the welding, which is caused by distance from the working area. Therefore, welders have to move to control the current and voltage by stopping welding. This, however, can result in the welding defects by momentary cooling. In this research related to the existing GMAW welding methods and the manners with the remote control torch their performances were evaluated by comparing and analyzing the welds of V-type butt using SM50A 6 mm and welding structural rolled steels. As the result of conducting the visual inspection and bending test one by one against the V-type butt welds, the amount of spatter by the remote control torch method showed reducing effects about five times lower and it had a performance that did not affect the weld defects by displaying suitable effects on the bending test of welds. Consequently, the experimental study on the possibility of replacement and compatibility with the existing commercial welder for the remote control torch was performed.
The monolithic glass, without damage, subjected to ballistic impact, is studied by the use of the coded finite element program. To analyze the impact response of monolithic glass like ordinary annealed glass and tempered glass, a finite element approach based on the Hertzian contact law and Sun's higher-order beam finite element is proposed. For verifying effectiveness of this finite element program, the contact force history is analyzed in conjunction with the loading and unloading processes. And, also, the time history of the impact responses such as the strain and stress according to the thickness changes due to transverse impact at the center are calculated
Biodiesel fuel as an alternative fuel for diesel engine has a great possibility to solve the problem such as air pollution caused by exhaust gas emission of the automobile. In this study, the usability of non-esterfied biodiesel fuel as alternative fuel is investigated in an indirect injection diesel engine. New concept biodiesel fuel has no glycerin generated by esterfication process and reduces the 20% of cost because of no use of methanol in the production process. Experiments were conducted by using the four blends with different volumetric percentage of biodiesel (0, 20, 50 and 100) in baseline diesel fuel. The smoke emission of biodiesel fuel was reduced in comparison with diesel fuel, but power and brake specific energy consumption was similar to diesel fuel
This study is done as a comparison analysis on existing studies on analysis and interpretations of solenoids. When there is no power in a solenoid valve, a flow passage is formed from a pressurized ports, Pc, to Ps, which are connected to a crankcase of a pressurizer. An inlet to Pc port is varied in three different sizes: 3.8 ㎜(Type-1), 4.0 ㎜(Type-2) and 4.2 ㎜(Type-3). It is determined that there will be changes in coolant flow into the solenoid valve and the flow properties from Pc port to Ps port are compared and analyzed. As the results, the flow demonstrates the maximum speed of 500 ㎧, 46 ㎧ and 433 ㎧ with 0.2 ㎫ for the inflow pressure and the maximum speed of 1400 ㎧, 129 ㎧ and 1200 ㎧ with 1.5 ㎫ for the inflow pressure.
In this article, to predict the wear amount of nano particles in a worn nano composite, computational analysis pre/post-processor were developed using ABAQUS and visual basic programs. The abrasion, which is one of nano particles release scenarios, was applied in the computational analysis. Moreover, reciprocation, which is the abrasion type, was selected and incarnated in abrasion computational analysis. Also, to predict wear amount of nano composite in computational analysis, archard equation was applied and the predicted wear amount was evaluated compare with experimental value. The predicted wear amount of nano composite was increased in accordance with increasing force and was similar to result of experimental value.
The monolithic glass, without damage, under impact loading, is studied by the use of the coded finite element program. To predict the impact energy of monolithic glass like annealed glass and tempered glass, a finite element approach based on Sun's higher-order beam finite element and impact energy equation is proposed. For this purpose, the contact force-displacements, energy-displacement histories and velocity-acceleration histories etc. are calculated during all impact processes. And, also, by the calculations of the coded FEM program, the geometric parameter like thickness is investigated to determine their impact energy prediction of monolithic glass.
A three dimensional numerical analysis was performed to study the effect of cathode inlet relative humidity on PEMFC performance characteristics. As cathode inlet relative humidity increases from 0 percent to 60 percent, the current density increases. Then, as cathode inlet relative humidity increases from 60 percent to 100 percent, the current density decreases. The two dimensional contour map analysis shows that the flooding phenomenon in cathode gas channel, gas diffusion layer, and catalyst layer leads to the decrease of current density.
The dissertation is on the measurement of the strain caused by the characteristics and the temperature changes of the TIG welded zone which is used with 3D ESPI system that is functionally modified through the laser ESPI system. Experimental results have derived from the fact that the welded zone has micro crack during the various phased of the process such as rolling, alkali cleaning, air cooling and heat processing due to the repetitious up-and-down of the temperature. Especially, both 60℃ and 90℃ are selected to measure the strain on the welded zone which can be effected by these two temperatures in the manufacturing process. The flat plate differences between ESPI and the strain gage are within 2 %, and they are the exactly same with the results from the temperature changes of 60 ℃ and 90 ℃, and also within 3 % and 4 %. As the tensile load increase, the strain of aluminum material increases linearly. Also the same effect are observed as the temperature goes up with irregular-line type. The comparison of the strain by ESPI and the strain gage in the welded specimen is within the 2.6% when it is under the room temperature and low-load conditions, while it is measured within 3 % under the high load condition.
Numerical analysis has been carried out to investigate particles behavior characteristics during the grinding process in the air. Grinding particles behavior is largely affected by many parameters such as operating conditions and process room geometry. Transient particle motion in the air is predicted, and the effects of particle diameter and device rotational speed on the behavior characteristics were compared. When particle size is not large enough, they shortly moves in a tangential direction of the device rotation, and then are mostly influenced by the air flow in the room. These results could be applicable to the optimal design of the grinding process room.
The latest weight reduction research of automotive industry and technology was improved. In this paper, we aim to evaluate the composite frame to manufacture the floor assembly of commercial vehicle. The design of subframe incorporated into the floor module was determined by FEM(Finite Element Method) simulation. The mechanical properties used for the simulations were obtained from the tests for samples of glass fiber/epoxy composites. We made two kinds of pultrusion products, one was aluminum profile, the other was unidirectional composites with aluminum profile. Based on the results from the simulation and bending test, the design of the subframe was finally determined prior to adoption of the commercial vehicle floor.
This research is to investigate the performance analysis of fuel cell for flow channel with four different types of the channel (Serpentine I, II, Inter-digitated, Parallel) in the fuel cell stack. Velocity, pressure. and temperature distributions of fluid over the flow domain of the flow channel are numerically calculated for the optimum design of flow channel with unifrom inlet velocity. According to the calculations of low pressure drop between inlet and outlet in the flow channel, Serpentine I type is of highest performance of the flow channel shapes in the present fuel cell model.
The improvement of car driving comfort is requested according to development of automobile manufacturing technology. Therefore, many experts have been studying automotive vibration of normally driving cars to improve automotive driving comfort. Vibration characteristics of a tire play an important role to judge a ride comfort ability and sound quality for a vehicle. A lots of study on the ride and the noise to reduce the vibration in the 20∼100Hz frequency range was being carried out for years. The tire impact due to the bump is the main factor of the vibration in the 20∼100Hz. This vibration is related to the harshness which perceive the displeasure or noise. In this study, we investigated the characteristics of the impact harshness due to the stiffness of the tire tread part according to change the tread compound.
This development is for non-destructive machine using X-Ray source about detecting outline faults of below middle size products. The market share of previous non-destructive machine has three major companies, such as GE, Siemens and Philips. In fact, Korea has a import of this product over 90 percentage. Fortunately, The major companies have not various kinds below middle size non-destructive machine. This machine has superior performance than previous X-Ray equipment in below middle size non-destructive machine. This machine is satisfactory needs for customers looking for X-Ray machine of a line detector. This research is for design and manufacturing of non-destructive X-Ray machine. This research will give rise to major effects for other various non-destructive market industries except car-industry. The most important fact is that this developed non-destructive machine is controlled below 0.2 micro-μSv.