This paper presents the detection and diagnosis of air-conditioner electromagnetic sound through noise measurements. Electromagnetic sound originating from the motor is an unpleasant source of unwanted noise that should be detected at the manufacturing stage. A detection system using sound measurements was built and a detection algorithm based on FFT analysis is presented. Sound measurements are preferable over direct vibration measurement because it is non-contact and low cost. Experimental results show that our sound measurement system can detect electromagnetic sound effectively compared to using vibration measurements.
This paper presents the design and simulation results of a piezo-driven motion stage that employs a novel cross hinge structure that is more efficient and flexible than previous designs. The newly designed motion stage enables close to nanometer-precision motion control with ranges up to 1.6mm. Simulation results show the effectiveness of the novel hinge structures and the performance of the proposed design.
The main milling cutter used for typical arthroplastic surgery robot, ROBODC system is 7.8 mm milling cutter. this cutter was used in case of traditional total knee arthroplasty, but 7.8mm milling cutter is not appropriate for newest surgical technique, MIS(minimally invasive Surgery). Generally, cutting method for MIS is tunnel cutting and cutter of cantilever type and small diameter is must be developed for MIS. Generally, Main problem of cutting system is chattering due to vibration of cutter by rotation and numerical analysis using finite element method was used for identifying chattering problems in this study. shaft length, cutter length, diameter and so on were proposed by axis displacement, stress, strain analysis through numerical analysis.
A kart is a vehicle without the suspension system and the differential gear. The kart frame as an elastic body plays the role of a spring. By the cornering of a kart, rolling, pitching and twisting motions are induced in the kart frame. Also the slip or noncontact of the wheel and a permanent deformation of the kart frame can be induced. In order to examine closely this phenomenon of the twisting deformation, measurement and analysis on torsion working stress with strain gage and tracking system are needed. According to the measurement result, while steady state driving in a curve in general the torsion working stress of the kart frame will be increased depending on the vehicle velocity, but the kart frame will be not permanent deformed. However, analysis of the torsion working stress in comparison with torsion fatigue limit shows that while unsteady state driving as clash with same drive condition the racing kart frame will be deformed more quickly as the leisure kart frame.
Experimental analysis has been carried out to investigate oil temperature control characteristics of the hydraulic system in a special vehicle. Hydraulic system performance is largely affected by oil temperature, and there are considerable malfunctions in the system for high temperature conditions caused by heavy load and continuous operation. Oil pressure in the hydraulic system decreases with oil temperature, and its variation rate becomes less steep as oil temperature increases. There is severe time delay for oil temperature control due to the operation of heat exchanger system, and it depends on the oil flow rate and pressure in the system. These results in this study can be applied to the design of automatic thermal control system in the special vehicle hydraulic system.
This paper shows how effectively sonar data can be worked with approaches suggested for the indoor SLAM (Simultaneous Localization And Mapping). A sonar sensor occasionally provides wrong distance range due to the wide beam width and the specular reflection phenomenon. To overcome weak points enough to use for the SLAM, several approaches are proposed. First, distance ranges acquired from the same object have been stored by using the FPA (Footprint-association) model, which associates two sonar footprints into a hypothesized circle frame. Using the Least Squares method, a line feature is extracted from the data stored through the FPA model. By using raw sonar data together with the extracted features as observations, the visibility for landmarks can be improved, and the SLAM performance can be stabilized. Additionally, the SP (Symmetries and Perturbations) model, a representation of uncertain geometric information that combines the probability theory and the theory of symmetries, is applied in this paper. The proposed methods have been tested in a real home environment with a mobile robot.
In this study, 3 kinds of motorbike models in common use are studied by flow analysis. The maximum velocity becomes 20 to 21 m/s at the upper part of models and the maximum air pressure resistances becomes 202 to 229 Pa at the front of models. Model 3 becomes the most uniform flow and model 1 becomes the most nonuniform flow among 3 models. In case of outlet planes on flow models, model 3 has the smallest velocity as maximum velocity of 17.49 m/s among 3 models. Model 3 has also the smallest velocity in case of middle planes on flow models. As model 3 has the most uniform air flow stream and the least air resistance than model 1 or 2, it can be thought to cut down on the power consumption.
High power and high efficiency has been required in internal combustion engine. Accordingly, the thermal load deformation, thermal stress and temperature on piston become higher at newly developed engines. To investigate the cooling effect of piston, a few types of piston design is presented and finite element method is carried out to analysis the heat transfer and the thermal stress. The piston which has upwards shifted cooling gallery is also analyzed to investigate the thermal load effect of oil jet cooling.
The purpose of this paper is to provide the optimal grinding conditions of metal components of a spectacles. The main elements of grinding conditions are composed of grain size, grade, structure, grinding wheel velocity and shifting components velocity. The conditions are co- related and influenced at each other. The precision of grinding surface was controled the each grinding conditions, mutual relations and reciprocal actions. It was studied the co-relations of grinding conditions those machining time-grain size-roughness, grade-roughness, machining time-characteristics of structure- roughness, number of production-roughnessgrinding wheel velocity, number of production-shifting velocity-grinding wheel velocity. The optimal grinding working condition satisfied the demanded surface accuracy 0.5 ~ 1.5μm. Based on these results, the optimal conditions were that the grain size was 60, the grade was middle of HIJK and LMNO, wheel velocity was 25 m/sec, shifting velocity was 15 m/min.
This study focuses on the realization of Fiber-Optic network's stabilization light source which is increasingly necessary according to the construction of the current high speed communication network. The stabilization light source is being used as an optical source in constructing the various Fiber-Optic networks, and developing the communication parts. And the light source consists of LED(light emitting diode) and Laser(light amplification by stimulated emission of radiation). LED has some merits, which are cheap and easy to treat, however the output is comparably small. And LED has some restrictions for transmitting the long distance because of broad line width. However, Laser, which has narrow line width and high output, is being used for transmitting the long distance and for the various LED and systems. This study develops the light source using Laser which is essential for the construction of communication networks as well as for the production and inspection of the communication parts. Considering for the portable, the stabilization light source, is developed light and easy to use, which has a structure using a small battery. As a result of an evaluation for the developed parts this study comes to know that an outstanding characteristic was realized because an accidental error occurred within ± 0.1[dB] not only in the characteristic of the initial motion but also in the 10 hour long operation. built-in.