This study aims to find an appropriate window for apartment to provide proper sound insulation. To achieve this goal, measured windows with various thicknesses of the sound insulation performance of inner air space and sound absorption materials in the inner air space. As a result of this study the improvement of the sound insulation performance of windows was shown through the analysis and the measuring of window these characteristics. These results may be applied to the manufacture of window frames and provide basic data for the improvement of the sound insulation performance of windows.
Metal matrix composites(MMC) can obtain mechanical characteristics of application purposes that a single material is difficult to obtain. Al2 O3/AC8A composites were fabricated by low pressure infiltration process. The purpose is establishing the optimal casting conditions for composite preparation under low pressure. It is known the inorganic binder help infiltration. Therefore Al2O3 fiber preform's optimum sinter temperature is 1160℃, added inorganic binder is mixed binder(SiO2 sol:Al2O3 sol=5:2). And three fibers have been compared (Al2O3 80%/SiO2 20%, Al2O3 80%/SiO2 10% and Al2O3 97%/SiO2 3%). Al2O3/AC8A composites was made by each melting temperatures(650℃, 700℃, 750℃) and wear test was performed about effect of temperatures, kind of fiber, matrix and composites, aging time. Wear test is Ball on disk wear test. The resistance increased with the low melting temperature and Al2O3 80%/SiO2 20% fiber.
Finite Element analysis were carried out to investigate the deformation behaviours of a buckled automotive seat frames made of three different types of materials, i.e., SAPH440, Al6082-T6 and Al7021-T7, when they were subject to external load, based on the ECE R14 regulation to achieve lightweight structure. Also, several thicknesses were applied to the seat frame structures of each material for characterising deformations. It was found that light weight seat frame structure was obtained compared to conventional steel structure when it was made of aluminium under the condition of satisfying ECE R14 regulation. Interpretation result, when changing from SAPHH440 material has a thickness of 1.5mm to Al material has a thickness of 3.0mm, that could checking weight lightening about 47%.
In this study, TbDyFe thin films with the thickness of 1000 Å are fabricated by DC magnetron sputtering. TbDyFe thin films are prepared by DC magnetron sputtering method. The pressure of Ar gas below 1.33 kPa and DC input power of 200 W are used for the sputtering conditions. During sputtering process the substrate holder is heated up to 150 ℃. The thin films are deposited to a thickness of 1000 Å on polyimide substrate with a thickness of 2 μm. The fabricated microstructures are observed by X-ray diffraction (XRD) and the film thickness is measured. Magnetostrictions are determined from the curvature of the thin films which are measured by the optical cantilever method. The experimental results are discussed with numerical data.
The MLCC electronic materials are used to make many industrial parts, for instance, such as smart phone, radio, LCD TV and so on. The screen ways and the rotor ways are known as methods that form electrode in MLCC. In these days, rotor ways have been frequently utilized because of its stability of quality. In this study, mixing characteristics for the inside of barrel of planetary mixer driver were investigated by numerical analysis using k-ε model of unsteady state, including effects for rotation and revolution. As the results, it showed that the flow of radius direction was mixed with regular pattern depending on time, however, the flow of longitudinal direction was mixed with same pattern regardless of time.
This study was purposed to develope a titanium alloy with low elastic modulus to be used as dental implant. The new titanium alloy was prepared as titanium alloy by adding Tantalum(Ta), Zirconium(Zr), Molybdenum(Mo) into the Ti-X-Y-Z system alloys. In designing the new titanium alloys, two physical variables bond order (Bo) and d-electron orbit energy level (Md) were varied. Mean bond order ( ) was around 2.818∼2.8784eV, and Mean d-electron orbit energy level ( ) was 2.4541~2.4747eV. In the cases of titanium alloys of T-3M and T-3Z, the XRD analysis showed β phase. On the other hand, the phase of α+ β were observed in the T-6Z and T-8Z alloys. Exhibited the highest hardness value to result in T-3Z 309.7Hv alloy Vickers hardness with respect to titanium alloy. In the resulting T-3Z alloy of measuring the elastic modulus value for a titanium alloy exhibited the smallest modulus of elasticity value to 89.81GPa. TEM analysis identified additional feature for T-3Z alloy was detected in addition to the ß-phase.
With increasing demands of transportation services for disabled or aged people, who need wheelchairs, it is recommended to install wheelchairs inside automotive vehicles. However, wheelchairs are not effectively safe devices during car crash unless they are properly fixed. So far, few data have been found related to wheelchair safety or characteristics during car crash, therefore, frontal crash simulations have been carried out based on the FE models of a dummy and a conventional wheelchair including the wheelchair fixing belts and the install plate in the present study. Head injury criteria (HIC) and motion criteria (MC) are investigated and the optimum value of the design variable was found by the Robust design.
Magnetostrictive actuator is fabricated with powder nano bonding method instead of sputtering method. Fabrication process and experimental measurement method for magneto-mechanical characteristics is proposed. For the design of highly flexible magnetostrictive actuator, TbDyFe nano powder bonding with Teflon substrate is adopted. The fabrication process for Teflon substrate and nano powder bonding is suggested and magnetostrictive behaviors are investigated. Variable magnetic field is applied to measure the magnetostrictive characteristics and magnetostriction is measured with different waves and different magnitude of magnetic field.
Through this study, velocity distribution characteristics of exit section and downstream straight length of square sectional 180° and 90° curved ducts were numerically analyzed with RSM (Reynolds Stress Model) by changing various flow parameters such as air velocity, surface roughness and hydraulic diameter etc. As a result of it, the maximum velocity profiles according to air velocity in 180° and 90° curved ducts were indicated at Y/D=0.8 and X/D=0.7 region. Also, the efficient measuring location in bended duct downstream was able to suggest when the most stable straight duct length in flow deviations were indicated at L/D=30 and L/D=10 region, and the standard deviation characteristics according to hydraulic diameter were mostly indicated at L/D=15∼30 and L/D=10 region considering minimum deviations in the same velocity condition.
Separately from a single body, crash box is maufactured into the two alumnae by bonding adhesive. Crashbox has the property to absorb the shock by impact transferred to the car body at the collision between cars. In this study, the structural effect and performance are investigated according to the positions of holes punched at this crash box. The optimal structure is investigated for optimal design data of aluminum crash box. The equivalent stresses of study models distributed by compressive loads are compared with each other by using the analysis program of ANSYS. Total energies and mechanical strengths of study models at the real situation are also analyzed. As analysis results, the maximum equivalent stresses of 40880MPa, 42368MPa, 43176MPa, 44960MPa and 43476MPa are shown at study models due to the hole positions of 10mm, 15mm, 20mm, 25mm and 30mm from the upper plane of crash box respectively. Also, the total energy on analysis are verified within the error range of 10 % by comparing that on experiment at the hole position of 10mm. It is thought that the crash box due to the hole position from the upper plane of crash box can be effectively designed through this study result.
A new design concept for integrated thermal energy storage system is suggested to increase energy saving rate for heating and cooling system of the closed glass greenhouse. Heat pump of air source is installed in the mechanical room and air flows then controlled by damper system located between the greenhouse and outdoor environments. A damper control algorithm is designed to enhance the usage of excessive energy in the glass greenhouse. Since the proposed system is installed at the actual glass greenhouse site for experimental verification of energy savings, the proposed system with damper control is compared with conventional greenhouse heating and cooling system. From results, it is found that more than 10% increase of energy saving rate is achieved.
As CFRP as the single material has various material properties, it has been used at many fields. CFRP is utilized at the mechanical structure on the basis of the brittle fracture property and the performance of vibration damping. CFRP composed of multiple axes has the high natural frequency. It is shown to have more reinforced material property with the fiber design. This paper investigates the fatigue property of the bonded specimen for mode 1 at the laminate angles of 30°, 45° and 60°. According to the fiber design, each specimen bonded with the laminate angle is shown to have different fatigue property repectively. As the laminate angle is increased, the reaction force tends to be increased. In this paper, the laminate angle through the fiber design of CFRP is applied and the fatigue property at mode 1 is investigated. Through the study result, The safety of fatigue fracture is also checked at applying to the composite structure.
The axial thrust acting on the turbocharger rotor is basically generated by the unbalance between turbine wheel gas forces and compressor wheel air forces. It has a significant influence on the friction losses, which reduces the overall efficiency and performance of high-speed turbocharger. Therefore, it’s important to calculate the thrust forces under operating conditions (surge, choke and etc.) in a turbocharger. The purpose of this paper is the development of numerical simulation methods which were verified by experimental results of axial thrust and thermally induced constraint tests of the turbocharger. The first FE model showed the relationship between thrust forces and strains by calculating the strains on specially designed thrust bearing and were compared with test results. And the second one is to identify the thermally induced strains in order to remove the thermal effects from measured strains. With these models, it’s possible to inversely predict the magnitudes of the axial thrust by directly measured strains and temperatures under operating turbocharger.
This experimental study was conducted to identify the correlation between speaker design factors and T/S parameters. For experiments to be conducted in the study, the sample speakers modified the damper, sub-cone, and mass of diaphragm of woofer speaker for vehicles were made to find characteristics of mechanical factors of speaker and non-linear factors; and the sound pressure characteristics were investigated. The correlation between design factors and T/S parameters showed that the strength of suspension system and the mass of motor part increased with the increase of mass of cone paper; and the force factor and resonance frequency tended to exhibit different behaviors according to the changes of damper.
In military, empty cartridge recovery case of personal small arms is a device used to collect the empty cartridge after consumption of bullets. It has different shapes depending on the shape of small arms. However, It should be designed in a shape that wraps around the outlet for empty cartridge and it should be no restrictions to the movement of small arms. It has been used to spread military. but military is demanding design improvement due to frequent damage of empty cartridge recovery case. In this report, We improved the shape of the product in order to prevent damage to the product and verified through the FEM analysis and prototype test. According to the result of simulation, best modified modelling of this study has been reduced about 19% of the stress compared to initial modelling. In addition, modified products were confirmed durability, wearability and fixability through fire test.
In this research, the inspection system for the concentricity of hole-saws through the image analysis is developed. The hole-saw, made by being rolled manually with bimetals, is the tool to make a hole in the wall. Its quality is definitely depended on the concentricity of hole-saws. However, it is difficult to check its concentricity and make a decision for the quality control without any automatic inspection system. This research made the automatic image analysis program based on the singular value decomposition model with only a webcam. Experimental results and evaluations demonstrate the validity of the proposed methods.
In this study, environmental new feeding and management system that are suitable for hot and cool water supply and floor heating system was developed and analyzed the effect for productivity and meat quality with supplying hot water in winter, the results were as follow as. HWSS was not affecting improvement with broiler productivity in initial time. Supplying hot water made the temperature inside broiler barn not go down rapidly as time went by from former term to latter term and continuous supplying hot water made boiler be adapted properly to the temperature and humidity of breeding environment that was requiring at its own growth phases. With unsaturated fatty acid / saturated fatty acids, HWSS was higher in broiler breast but CWSS was higher in the leg. With AST, ALT in blood, HWSS is higher than CWSS but with neutral lipid, protein, glucose, albumin, cholesterol, HWSS is higher than CWSS. Water circulation heating system gave an impact on meat quality and PH showed a higher in CWSS system. Also, redness and yellowness of the meat color was confirmed to be greater in HWSS. It was proved that the temperature difference of drinking water affected farm productivity, the blood and flesh quality, therefore, that could be estimated to be utilized successfully, if that should be used appropriately for productivity improvement according to the week-old of growth phase.
The suspension system of special tracked vehicle is using hydraulic piston pump to adjust track tension and control vehicle position change. During operation of vehicle on rough field, failure of suspension control was occurred due to the piston pump failure. In this study, investigation was performed to analyze the cause of hydraulic piston pump failure. Main reason of piston pump failure is strong peak pressure and insufficient structural safety of shoe. The static stress analysis considering peak pressure was performed to find the weak point of the shoe. From the result, it is confirmed that pass hole of lubrication is the weakest point. Improved piston shoe shows 27% decrease in maximum stress and satisfies the design target which is less than 40% of stress margin.
In this study, new Continuously Variable Transmission(CVT) system which is adaptable to a small size electric vehicle is proposed available to gradient response CVT. New pulleys consist of springs adapted driving pulley and driven pulley. At the moment a small electric vehicle drive a slope, new system respond to a gradient as overcoming tensional force of springs. We made prototype of gradient response CVT to test parts performance. As a result of test, belt pitch diameter varied for high torque direction at the gradient.
In order to guarantee reliability of the environmental testing on defense systems, it is important to use test equipment that meets requirements of the related test standards. Especially with regard to the rain test method in MIL-STD-810G w/change 1, the latest standard, it has been highly needed to introduce a novel technique and system to provide droplet-size and precipitation-rate conditions. In this study, droplet-diameter spectra of various nozzles were measured by a high-speed camera. Then, a pair of nozzles were selected based on the experimental results showing the spectra lie within the range from 0.5 mm to 4.5 mm, as suggested in the rain test method. Also, the flow-precipitation rate calibration system was developed to precisely correlate the precipitation rate measured in the chamber and the flow rate into the nozzle bank. In conclusion, the rain test equipment has been successfully developed fulfilling the requirements of the test standard.