Papers by Author: Jae Yeol Kim

Abstract: Extrusion screw that is used on market of present extrusion molding catapult is divided by single-axle extrusion screw and multi-axles extrusion screw. Simulation technique of screw that is used in extrusion molding has become so far various. Consist of that analyze third dimension model and that analyze two-dimension model but most Analysis that display dynamic characteristic of screw inside of heat and flow in detail was not until present. Transfer of polymer site that typical single-axle extrusion screw that is analysis target of this treatise is mixed in most melting state is good, but has some controversial points. First melting transfer of balance that is not done difficult. Second melting causes effect that weaken mechanical special quality of screw by power excessive last month if heighten the screw speed to increase amount of done balance. Third Screw dynamic characteristic symptoms by thermal expansion that happen in screw of heater is fallen.

Abstract: We present a study on the development of a practical and quantitative technique for the assessment of the structural health condition with using piezoceramic (PZT) sensors. The electroimpedance- based technique with the PZT patches is very sensitive for evaluation of the incipient and small damage in a high frequency range, and however the commonly traditional modal analysis method is effective only for considerably larger damages in low frequency range. The paper presents the performance of the performance of the electro-impedance-based technique in detecting and characterizing real-time damage on the specimen that is an aluminum plate fastened with bolts and nuts by different torques. By using the special arrangement of the PZT sensors, the required longitudinal wave is generated through the specimen. A large number of experiments are conducted and the different conditions of the specimen, i.e. the location of loosening bolts and the loosening extent of bolts are simulated, respectively. Since fixing and loosening the loosened bolt is controlled by a torque wrench, we can control exactly the experiment of the different torques. Compared with the simulated healthy condition, we can find whether or not there is a damage in the specimen with using an impedance analyzer with the PZT sensors. Several indices are discussed and used for assessing the different simulated damages. As for the location of bolt loosening, the RMSD is found to be the most appropriate index for numerical assessment and as well the RMSD shows strongly linear relationship for assessing the extent of the bolt loosening. The possibility of repeatability of the pristine condition signatures is also presented and the appropriate frequency range and interval are uniquely selected through large numbers of experiments. The analytical results strongly show the sensibility and reliability of the electro-impedance based technique.

Abstract: The Infrared Camera usually detects only Infrared waves emitted from the light in order to illustrate the temperature distribution. An Infrared diagnosis system can be applied to various fields. But the defect discrimination can be automatic or mechanized in the shoes total inspection system. The thermal images of the specimens were analyzed. In shoes, weak bonding due to the separation of the bonded parts delamination causes defects. The most serious defect occurs in the bonding between the outer covering of the shoe and the sole, and to up now, this defect has been detected only by inspection with the naked eye. This study introduces a method for special shoes nondestructive total inspection. Performance of the proposed method is shown through thermo-Image. In search of superior inspection methods, we evaluated an applicable non-destructive inspection method and also carried out basic research for developing an innovative nondestructive inspection system for shoes. The total inspection system using infrared thermal camera for special shoes, its applicability, and system configuration are introduced.

Abstract: In this investigation, we evaluated diagnoses of a defect concerning coating of land-base gas turbine using infrared thermography camera. In this camera method has a strong point which is able to save time and costs compared with former method. Because it can be long field acquire temperature distribution by using non-contact method. But it has a week point that method applies thermal load about inspection sample. Presently, Method used widely in detection of crack is ultrasonic inspection. But this method, There is problem in application in place that uneven surface. In order to check cracks on a blade coating of a gas turbine, a part with cracks in a waste blade disposed after having been used in the field was extracted to produce a sample. So we apply the method by a infrared thermography camera to the produced sample, the sample was heated by means of a halogen lamp. In this paper, we want to describe production of land-base turbine sample, a method of applying thermal load at produced sample, infrared thermography camera technique, an analysis technique of thermography, a defect analysis of coating of land-base gas turbine blades.

Abstract: After Industrial Revolution, energy has been recognized as an important factor which enhances the motive power for industry in the industrial society. However, recently the excessive consumption of energy pursuant to the rapid expansion of industry created serious problems of the exhaustion of fossil fuels as well as unusual change in the weather due to the mass discharge of carbon dioxide. We can say that after all proposals will boil down to the development of New & Renewable energy. The most suitable source of energy for this required change is solar energy. The advantages of solar energy are that it is renewable, infinite supplied and environmentally safe energy source, and the method of energy supply is in small scale and is decentralized. However, solar energy related products have the problems such as the limitation for installation, problems in maintenance and insufficient reliability, which have been the barrier to consumers to satisfy the purchase need for solar heat related products. In this research will perform thermodynamic analysis through the application of infrared ray thermal imaging camera and will discuss about the applicability of solar energy system and other fields as well.

Abstract: In this research, we used nondestructive test based on ultrasonic test as inspection method, and made up inspection robot in order to control of ultrasonic probe on the SWP surface, and programmed to signal processing code and pattern classifying code by user made programming code. For evaluation of flaw signal is reflected on welding flaw, user-made program codes are composed of signal processing and probability neural network (PNN) and backpropagation neural network (BPNN). And then, we actually confirmed to the theoretical advantage of each neural network method compared probability neural network with backpropagation neural network for classification and recognition rate. For the application of classifier to SWP inspection system, BPNN classifier is adequate in the first stage. And then, the application of PNN classifier is adequate as the next stage. Because of PNN application need enough sample data that is due to probabilistic density function.

Abstract: Contact type detection, one of UT for the detection of defects in welding area, has several weak-points. Proximity type ultrasonic inspection using laser is being studied these days to make up for the weak points of contact type ultrasonic inspection. In this paper, automatic inspection system of the welding area of spiral welding pipe has been developed, of which mechanical characteristic is better than that of circular directional pipes, and executed the proximity ultrasonic inspections using laser. The usefulness of proximity ultrasonic inspection using laser will be verified in this paper through the analysis of the inspection results.

Abstract: Recently, the demand for Ultra-precision products is rapidly increasing, especially in such industries as semi-conductors, computers, aerospace, and precision machinary. Ultra-precision processing is also extremely needed for NT in the field of mechanical engineering. Lately, together with drastic advancement of electronic and photonics industry, the need of Ultra-precision processing is increased in the manufacturing of various kernel parts, which are connected with these industrial fields. Especially, motion accuracy to nanometers is required in order in stroke of hundreds millimeters according as the diameter of the processed object great and the processing accuracy rises. In this case, the response speed absolute delay due to inertial mass of the moving parts is very large. Therefore, real-time motion error compensation becomes the barest necessity. In this paper, we used ultra-precision cutting unit (UPCU) to cope with the problem. A special UPCU was designed and tested to obtain sub-micrometer from accuracy in diamond turning of flat surfaces. The thermal growth spindle error was compensated in real time using the UPCU driven by piezoelectric actuator along with a laser encoder displacement sensor.

Abstract: The main purpose of this investigation was to evaluate the performance of the solar hot water heater for dwellings in a long period of time. In order to evaluate the performance, there were 11 solar hot water heaters located in Gwangju Chosun University examined for their performance in 30 month period as a long term. The specific monitoring systems of each heater were constructed for the demonstrational research and the data base associated to each monitoring systems were assembled for an extensive analysis for variety of data obtained. The demonstrational experiments were conducted through following the routine procedures of 4 specific tests (the replicated drainage test, the daily drain test, the daily agitation test, the short-term test). The performance evaluation was based on the performances in insulating and solar collecting and the experimental routines and the performance experiments had incorporated the consumers’ use and need of the product. The ultimate goals of this investigation were to achieve consumers’ trust on the products and to promote the extensive distributions of the solar hot water heaters. The demonstrational research of this investigation was to evaluate the performance of the solar hot water heater for the residents for a long period of time. This research will be continued extensively.