Papers by Author: Jae Yeol Kim

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Authors: Seung Hyun Choi, Jae Yeol Kim
Abstract: Spread of household air conditioning system is continued to be increased. Along with the spread, the acknowledgement on product quality by the customer is increasing. Therefore, not only basic performances like cooling and power consumption but also design and noise level of in-house and external unit become the important factors. Axial fan in the external unit of air conditioning system is for ventilation and air supplying unit, and the related products have been widely adopted as household electronics, automobile engine, big sized blower in factory, tunnel, and subway. In this study, commercial 3-winged propeller fan from S company is modified to 2-winged fan for the cost reduction. Using 3D modelling, the fan shape is modified, and analysis flow is adopted to provide the way to reduce cost while maintaining the same wind capacity.
Authors: Nam Su Kwak, Jae Yeol Kim, Dae Gwang Park
Abstract: In this study, piezoelectric actuator, flexure guide, power transmission element and control method are considered for nanopositioning system apparatus. The main objectives of this thesis were to develop 2-axis nanostage which enables 2-axis control with the aid of piezoelectric actuator, and to improve the precision of the ultra-precision lathe (UP2) which is responsible for the ductile mode machining of the hardened-brittle material where the machining uses a the single-crystal diamond. Through simulation and experiments on ultra-precision positioning, stability and priority of the nanopositioning system with 2-axis nanostage and control algorithm are developed using Matlab/Simulink. Then the system, is applied to analyze surface morphology of the titanium alloy (Ti-6Al-4V)
Authors: Jin Ho Choi, Seung Hyun Choi, Kyung Seok Song, Jae Yeol Kim
Abstract: For the analysis of various extruder models are used not only testing, but also diverse simulation techniques. Of them, the three-dimensional technique is widely used recently. In this study, the breaker plate in a polymer resin extruder was analyzed. The breaker plate changes the rotational motion of the polymer resin extruded from the screw barrel into a straight line motion before it passes through the die. Also, the size and number of circular holes in a breaker plate directly affect polymer resin extrusion molding. In this study, a 3-D modeling was used to conduct the structural improvement of breaker plates, and the thermal/flow analysis program CFdesign was used to conduct a dynamic property analysis in a bid to achieve the production stability of extruders.
Authors: Jae Yeol Kim, S.U. Yoon, Kyeung Cheun Jang, Myung Soo Ko, Jae Sin An
Abstract: In the present study, a Nd;YAG Laser (pulse type) was used to emit ultrasonic signals to a test material. In addition, a total ultrasonic investigation system was designed by adopting a Fabry-Perot interferometer, which receives ultrasonic signals without any contact. For non-destructive test SM45C, which contains some flaws was used as a test material. Because it is easy to align light beam in receiver, and the length of the light beam does not change much even if convex mirror leans towards one side, confocal Fabry-Perot interferometer, which has stable frequency, and PI control are used to correct interfered and unstable signals from temperature, fluctuation and time shift of laser frequency. Stable signals are always obtained by the feedback of PI circuit signals in the confocal Fabry-Perot interferometer. The type, size and position of flaws inside the test material were examined by achieving the stabilization of an interferometer. This study presented a useful method, which could quantitatively investigate the fault of objects by using a Fabry-Perot interferometer.
Authors: Kyung Seok Song, Myung Seok Ko, Jae Yeol Kim
Abstract: Importance on the detection of corrosion-related defect is undeniable from the fact that it can prevent significant economic loss and enhanced safety in mechanical equipments, pipes, ships, bridges, and other applications. Conventionally researched measurement methods for defect and thinning from corrosion are acoustic emission, EMAT using ultrasound, laser induced ultrasound, etc. However, these non-destructive testing methods have the shortcoming of accessibility to on-site. For instance, EMAT should be close to several millimeters to generate magnetic field in structure. For laser application, it can be applied to remote non-destructive testing, but some defect might not be possible to be detected by the surface condition of structure. In this study, infrared thermography camera is utilized to determine the degree of corrosion on paint-coated metal. In addition, fundamental researches to develop corrosion detection system for on-site metallic structure are conducted to provide the applicability of IR camera and possibility of thermal analysis method.
Authors: Choul Jun Choi, Jae Yeol Kim, Dong Jo Yang, Kyung Seok Song, Yeon Shik Ahn
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.
Authors: Dong Jo Yang, Jae Yeol Kim, Jae Ho Han
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.
Authors: Jae Yeol Kim, Lee Ku Kwac, Jae Ho Han
Abstract: Recently, the world is preparing for new revolution, called, ‘IT(Information Technology), NT(Nano-Technology), and BT(Bio-Technology).’ NT can be applied to various fields such as semiconductor-micro technology. Ultra precision processing is required for NT in the field of mechanical engineering. Because of radical advancement of electronic and photonics industry, necessity of ultra precision processing is on the increase for the manufacture of various kernel parts. In this paper, stability of ultra precision cutting unit is investigated and this unit is the kernel unit in ultra precision processing machine. According to alteration of shape and material of hinge, stability investigation is performed. Hinge shapes of micro stage in UPCU (Ultra Precision Cutting Unit) are designed in two types, where, hinge shapes are composed of round and rectangularity. Elasticity and strength are analyzed on micro stage with respect to hinge shapes by FE analysis. The micro stage in ultra precision processing machine has to keep hinge shape under cutting condition with 3-component force (cutting component, axial component, and radial component) and to reduce modification against cutting force. Then we investigated its elasticity and strength under these conditions. The material of the micro stage is generally used for duralumin with small thermal deformation. Since the elasticity and the strength quiet become important, the stability of the micro stage is investigated. Used materials are composed of aluminum of low strength and cooper with medium strength and spring steel with high strength. Through this stability investigation, trials and errors are reduced in design and manufacture at the same time, and we are accumulated foundation data for a unit control.
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