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방세윤,성관제,Bang Se-Yoon,Seong Kwan-Je 대한용접접합학회 2005 대한용접·접합학회지 Vol.23 No.2
A numerical model for multiple reflection effects of a polarized beam on laser grooving has been developed. The surface of the treated material is assumed to reflect laser irradiation in a fully specular fashion. Combining electromagnetic wave theory with Fresnel's relation, the reflective behavior of a groove surface can be obtained as well as the change of the polarization status in the reflected wave field. The material surface is divided into a number of rectangular patches using a bicubic surface representation method. The net radiative flux far these patch elements is obtained by standard ray tracing methods. The changing state of polarization of the electric field after reflection was included in the ray tracing method. The resulting radiative flux is combined with a set of three-dimensional conduction equations governing conduction losses into the medium, and the resulting groove shape and depth are found through iterative procedures. It is observed that reflections of a polarized beam play an important role not only in increasing the material removal rate but also in forming different final groove shapes. Comparison with available experimental results for silicon nitride shows good agreement for the qualitative trends of the dependence of groove shapes on the electric field vector orientation.
방세윤(Se Yoon Bang) Korean Society for Precision Engineering 2005 한국정밀공학회지 Vol.22 No.7
In laser machining such as drilling with C0₂ or Nd:YAG laser, and etching or ablation with Excimer laser, one of the most important parameters affecting the machining is known to be beam characteristics. In this paper a numerical study is performed to investigate the effects of beam parameters, especially in the process of excimer laser ablation of polymers. Results of different beam conditions reveal that if the ablated depth is small compared to beam size the simple photochemical etching model is suitable to predict the etched shape, and that the importance of precise alignment becomes large as beam quality factor becomes larger.
방세윤(Se Yoon Bang) Korean Society for Precision Engineering 2017 한국정밀공학회지 Vol.34 No.11
An integrated simulation program for virtual laser ablation is developed to help understand and predict the effects of machining parameters on the final machined results. The main solver of the program is based on the model for polymer ablation with short-pulse Excimer lasers. The GUI of the program is built using Visual Fortran and OpenGL so that the user can work in a visual environment, such as Windows on a PC, where the important machining parameters can be input via a dialog box and the calculated results for the machined shape can be plotted by means of a 3D graphics window using OpenGL. The developed GUI can be implemented for use with most pre-developed FORTRAN solvers for Windows application, allowing the user to control the input parameters and to see the results in a 3D plot; hence most FORTRAN users could create their own visual programs on PC Windows systems similarly, widening the range of application of FORTRAN solvers.
방세윤(Se Yoon Bang),신귀성(Kui Sung Shin),윤경구(Kyung Koo Yoon),황경현(Kyung Hyun Whang) Korean Society for Precision Engineering 2005 한국정밀공학회지 Vol.22 No.7
This paper summarizes the work on the development of a simulation program for modelling the process of machining quasi-three dimensional shape with the excimer laser beam on a constantly moving polymers. Relatively simple masks of rectangle, triangle and half circle shape are considered. The etching depth is calculated by considering the number of laser pulses irradiated on the specimen surface. It was found that similar shapes as experimental results can be obtained by choosing suitable parameters of moving velocity, moving distance and mask sizes.
방세윤(Se Yoon Bang),이호용(Ho Yong Lee),임중연(Joong Yeon Lim),신귀성(Kui Sung Shin),윤경구(Kyung Koo Yoon),황경현(Kyung Hyun Whang) Korean Society for Precision Engineering 2005 한국정밀공학회지 Vol.22 No.7
A simulator for virtual laser machining is developed to help understanding and predicting the effects of machining parameters on the final machined results. Main program is based on the model for polymer ablation with short pulse excimer lasers. Version I of the simulator is built using Visual Fortran to make the user work under visual environment such as Windows on PC, where the important machining parameters can be input via dialog box and the calculated results for machined shape, beam fluence, and temperature distribution can be plotted through the 2-D graphics windows. Version Ⅱ of the simulator is built using HTML, CGI and JAVA languages, allowing the user to control the input parameters and to see the results plot through the internet.
윤경구(Kyung Koo Yoon),방세윤(Se Yoon Bang) Korean Society for Precision Engineering 2005 한국정밀공학회지 Vol.22 No.9
To investigate the effects of beam focusing in the etching of polymers with short pulse Excimer lasers, a polymer etching model of SSB's is combined with a beam focusing model. Through the numerical simulation, it was found that in the high laser fluence region, SSB model considering both photochemical and thermal contribution is considered to be suitable to predict the etched hole shape than a simple photochemical etching model. The average temperature distribution into the substance obtained by assuming 1-D heat transfer is found to be fairly similar to the fluence distribution on the ablated surface. The experimental etching data for polymers are used to give material properties for ablation model. The fitted etch depth curve gives a nice agreement with the experimental data.