Browsing by Author "Hsu, Keng-Wei"

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A NOVEL METHOD FOR LOCATING SOLDER JOINTS BASED ON MODIFIED BINARY POTENTIAL FUNCTION
(2012-01-01)
Su, Miin-Tsair
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Lin, Chin-Teng
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Hsu, Keng-Wei
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電機工程學系
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Department of Electrical and Computer Engineering
The solder joint location on inductors is an extremely important aspect of the industrial process; in particular, the visual location plays a fundamental role. The visual-location process is often carried out by human experts. The disadvantages associated with manual location are the large amount of time required and reduced efficiency as operator fatigue occurs. In addition, as electronic products now tend to be miniaturized, portable and with dense component layout, manual location is becoming unreliable. This has prompted the development of automatic visual-location systems to speed up the location process, increase production efficiency and improve manufacture yield rate. In this paper, we propose an automatic visual-location method for solder joints to address the problem of feature extraction in digital images, using the concept of potential functions (PF). In order to make the location method more suitable for the inductor industry, the virtual external electric field concept is introduced. The proposed location system, which uses modified binary potential functions (MBPF), has been implemented and tested with three kinds of inductors. The experimental results show that the proposed scheme performs with a high degree of accuracy, even with testing samples that are significantly different in appearance.
Modeling an Uncertain Productivity Learning Process Using an Interval Fuzzy Methodology
(2020-06-01)
Chiu, Min-Chi
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Chen, Tin-Chih Toly
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Hsu, Keng-Wei
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工業工程與管理學系
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Department of Industrial Engineering and Management
Existing methods for forecasting the productivity of a factory are subject to a major drawback-the lower and upper bounds of productivity are usually determined by a few extreme cases, which unacceptably widens the productivity range. To address this drawback, an interval fuzzy number (IFN)-based mixed binary quadratic programming (MBQP)-ordered weighted average (OWA) approach is proposed in this study for modeling an uncertain productivity learning process. In the proposed methodology, the productivity range is divided into the inner and outer sections, which correspond to the lower and upper membership functions of an IFN-based fuzzy productivity forecast, respectively. In this manner, all actual values are included in the outer section, whereas most of the values are included within the inner section to fulfill different managerial purposes. According to the percentages of outlier cases, a suitable forecasting strategy can be selected. To derive the values of parameters in the IFN-based fuzzy productivity learning model, an MBQP model is proposed and optimized. Subsequently, according to the selected forecasting strategy, the OWA method is applied to defuzzify a fuzzy productivity forecast. The proposed methodology has been applied to the real case of a dynamic random access memory factory to evaluate its effectiveness. The experimental results indicate that the proposed methodology was superior to several existing methods, especially in terms of mean absolute error, mean absolute percentage error, and root mean square error in evaluating the forecasting accuracy. The forecasting precision achieved using the proposed methodology was also satisfactory.
Orientation effect on heat transfer of a shrouded LED backlight panel with a plate-fin array
(2013-03-01)
Shyu, Jin-Cherng
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Hsu, Keng-Wei
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Yang, Kai-Shing
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Wang, Chi-Chuan
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機械工程學系
This study reports thermal performance of a shrouded 348 mmx 558 mm aluminum plate-fin heat sink subject to various input powers and orientations. Effects of clearance (C) and the orientation on the heat transfer of the heat sink were investigated. Results show that the clearance effect is detectable only in a "window region" between 5 mm and 10 mm where an appreciable rise of heat transfer coefficient is encountered. As the tilted angle (theta) of the LED panel is increased, the heat transfer coefficient is reduced and the clearance effect on heat transfer becomes more pronounced. The heat transfer coefficients are similar between two cases in which the tilted angles of the LED panel are supplementary irrespective of clearance and input power. Except the cases of a horizontal heat sink, heat transfer coefficient of the shrouded heat sink having a fin array facing downward is usually slightly higher than that having supplementary tilted angle. (C) 2012 Elsevier Ltd. All rights reserved.
Thermal characterization of shrouded plate fin array on an LED backlight panel
(2011-10-01)
Shyu, Jin-Cherng
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Hsu, Keng-Wei
;
Yang, Kai-Shing
;
Wang, Chi-Chuan
;
機械工程學系
This study experimentally investigates a 348 mm x 558 mm LED backlight panel consisting of 270 1-W LEDs and a plate-fin heat sink in an acrylic housing. Effects of shroud clearance, obstructions at entrance or exit on the overall performance are also examined. The results show that the heat transfer coefficient is very slightly reduced with the rise of shroud clearance from 0 mm to 5 mm, followed by a notable rise but it peaks at a shroud clearance between 10 and 20 mm. A further increase of shroud clearance leads a marginal decrease of heat transfer coefficient. It is found that the maximum temperatures within the LED panel are not necessarily located at the center region due to the edge effect. On the other hand, the temperature variation along the longitudinal direction indicates a local minimum Nusselt number occurring near the exit of LED panel. This unique phenomenon is associated with the development of velocity and temperature field, and is consistent with previous numerical examinations. On the other hand, the obstruction placed at the exit are often severe than at the entrance. (C) 2011 Elsevier Ltd. All rights reserved.