• Journal of the Korean Society of Manufacturing Process Engineers
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• v.21 no.2
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• pp.46-53
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• 2022

This paper presents the design and manufacture of a Solid State Relay (SSR) life prediction device that can predict the lifetime of an SSR, which is a key component of a glass forming machine. The lifetime of an SSR is over when the current supplied to the relay is overcurrent (20 A or higher), and the operating time is 100,000 h or longer. Therefore, the life prediction device for the SSR was designed using DSP to accurately read the current and temperature values from the current and temperature sensors, respectively. The characteristic test of the manufactured non-contact relay life prediction device confirmed that the current and temperature were safely measured. Thus, the SSR lifetime prediction device developed in this study can be used to predict the lifetime of an SSR attached to a glass forming machine.

• Composites Research
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• v.24 no.6
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• pp.31-36
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• 2011

According to the evaluation on GMT-sheet by molding conditions, fiber projection on the moldings surface was investigated. Fiber projection is one of the major defects on moldings surface due to matrix shrinkage. That is, fiber projection happens from different shrinkage of matrix and glass fiber. Height of fiber projection from moldings surface becomes smaller when molding pressure is higher during holding pressure and cooling process. Height of fiber projection is dominantly affected by molding pressure. With consideration of molding pressure, the formation of surface unevenness and change in fiber projection height was elucidated. In addition, coating layer is effective to suppress surface defects, and there is no fiber projection or crack in case that coating is applied. Coating layer improves surface roughness up to the level of the polypropylene which is a single material.

• Journal of the Institute of Convergence Signal Processing
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• v.5 no.1
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• pp.40-45
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• 2004

This paper presents the parallel distributed control scheme for shaping of the bent glass. The designed system consists of a PC, a main controller and 11 servo-controllers, the precision motion controllers. Each elements are connected by using RS-232C and 8-bit data bus. In order to guarantee the stability and the control performance, we use a precision PID motion controller and a H-bridge on the servo-drivers. PC calculates position values of 11 DC motors by using the pre-determined curvature value and offers the user interface environment operator. The main controller provides the control instructions and parameter values to 11 servo-controllers by chip enable signal, simultaneously. Using the received commands and parameter values, the servo-controllers control the positions of the DC motors based on PID control scheme.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.19 no.6
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• pp.43-48
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• 2020

This study explores the compression molding of diffractive-aspheric lenses using GeSbSe chalcogenide glasses. A mold core with diffractive structure was prepared and a chalcogenide glass lens was molded at various temperatures using the corresponding core. The effect of molding temperature on the transcription characteristics of diffractive structure was examined, by measuring and comparing the diffractive structure between the mold core and the molded chalcogenide glass lens using a microscope and a white light interferometer. In addition, the applicability of the molded lens for thermal imaging was evaluated, by measuring the form error.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.19 no.6
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• pp.36-42
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• 2020

Nowadays, the touch screen panel (TSP) cover glass for mobile smart devices is being developed with a curved glass shape due to different design requirements. Because the sizes of mobile smart devices continue to increase, there has also been a great increase in the demand for large-area curved glass greater than 20 inches. In this study, heat and fluid flow analysis using CFD was performed to optimize the heating surface temperature distribution of the large curved glass formation system. Five cooling water flow paths in the cooling block were designed and analyzed for each case. A function that can quantitatively calculate the temperature uniformity of the heating surface was proposed and these values were obtained for the five models. The temperature distributions of the heating surface and the energy consumption of the heating system were also compared and comprehensively analyzed. Based on the analysis results of the five different cooling channel path models, the optimal path design could be presented.

• Proceedings of the KAIS Fall Conference
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• 2004.06a
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• pp.86-88
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• 2004

본 연구에서는 고주파 이동통신 기기용 칩형 세라믹 안테나의 사용을 위한 저유전율 및 저온동시소성이 가능한 CaO-B2O3-SiO2계 유리를 제조하고자 하였다. 제조된 CaO-B2O3-SiO2계 유리는 열분석을 통하여 낮은 연화온도를 갖는 안정한 유리조성을 선정하였다. 유리분말을 이용하여 성형된 샘플은 소결온도에 따른 특성을 조사하였다. 소결온도변화에 따라 유전율(${\epsilon}_r$)은 4-4.5값을 나타냈으며, 유전손실(tan$\delta$)은 <$0.1\%$ 보였으나, 품질계수(Q$\times$f)는 큰 변화폭을 보였다.

• Proceedings of the KAIS Fall Conference
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• 2010.11b
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• pp.824-827
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• 2010

본 논문은 전동형 모터의 Rotor의 자동 성형을 위한 자동화된 주조기 개발에 대한 결과이다. 개발된 자동화된 Rotor 전용 주조기는 수평형에 비해 금형의 크기가 약 1/2정도 이므로 금형 체결력이 반감되고, 기계 구조는 매우 작아진다. 그리고 Al용탕이 사출되는 과정에서 Spool -> Runner -> Gate -> Cavity(제품)에 이르기까지의 Runner를 최소화하여 재용융을 위한 에너지의 비용 절감을 할 수가 있다. 금형 구조가 간단하므로 금형비가 저렴하여 다품종 소량생산에 매우 유리하다. 개발제품은 수직형 구조로 알루미늄 용탕의 윗면의 공기가 금형의 유로 상측에 위치하므로 공기(gas)가 먼저 배출되어 사출(주조)후 Rotor 성형부에 남아 있는 기포가 최소화된다. 그러므로 충진도가 높아진다. Rotor 코아(규소강)가 크더라도 수직형은 금형내에 삽입(Inset)하기가 쉽고 또한, 제품의 착탈 부위와 사출부위가 다르기 때문에 작업성, 안전성이 우수하고 생산성이 매우 높다. 수직형은 충진 밀도가 매우 높고 밀도가 균일하기 때문 Rotor의 회전 소음, 진동에 대한 품질이 매우 우수하다. 따라서 고효율, 고품질의 전동모터 Rotor 제품 생산에 매우 효과적인 장비라 할 수 있다.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.11
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• pp.1649-1657
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• 2010

We have investigated the unexpected phenomena on the surface of molded GFRP composites. The major cause of the unevenness, as a result of which the surface becomes rough, is a shrinking of the matrix in the process of holding pressure and cooling temperature. The higher holding pressure load in a molding process and the lower demolding temperature in an annealing experiment, the better GFRP composites moldings improved its appearance. In addition, by taking the holding pressure and demolding temperature into consideration, we evaluate the process that causes the surface unevenness and the variation in the fiber projection height.

• Elastomers and Composites
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• v.35 no.2
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• pp.115-121
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• 2000

In comparison with thermosetting rubber, thermoplastic elastomer (TPE) has various advantages such as simple processing, short cycle time and recycling of scrap. These advantages can lead to development of the high value-added rubber products due to reduction of the waste material, manufacturing cost and the defected product. This article involves a dynamic vulcanization method for EPDM/polypropylene blend, and the manufacturing of a fixed glass weather-strip by glass insert molding method using the blend. In order to investigate mechanical properties of the product, tensile strength, elongation, hardness and specific gravity were measured. Also morphological study was carried out using SEM. Developments of an efficient system of production and automatic process by molding of TPE and glass simultaneously are expected.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.5
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• pp.80-85
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• 2016

Carbon fiber-reinforced composite materials have been widely used in various industrial fields, but there are limits to increasing their strength and stiffness, because of the short-length fibers that are impregnated in them. In this study, a lab-scale small extruder system was developed with the capability to perform the carbon fiber impregnation and extrusion process in order to evaluate the properties of long-length carbon fiber reinforced thermoplastic composite materials molded by the LFT-D method. Specimens were made with the small extruder to press-mold long-length carbon fiber composite materials and evaluate their material properties. As a result, it was found that the carbon fiber length, press load and carbon fiber contents have a considerable influence on the strength and stiffness. Additional studies on such factors as the mixing screw design and coating of the carbon fiber are needed in order to improve the mechanical properties of carbon fiber composite materials.