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"Sajan Tamang"

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"Sajan Tamang"

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A Study on Numerical Analysis for Determination of Glass Molding Process Conditions for Glass Lenses
Jaehun Choi, Sajan Tamang, Heesung Park
J. Korean Soc. Precis. Eng. 2024;41(3):207-214.
Published online March 1, 2024
DOI: https://doi.org/10.7736/JKSPE.023.136
The Glass Molding Process (GMP) produces large quantities of glass optical parts and provides the advantages of high molding accuracy, short production cycle, low cost, and little pollution. Developments in different sectors, such as cameras and telescopes, are prompting studies on the design of aspherical optical components. Modeling heat transfer and deformation at high temperatures are crucial aspects of studying glass because its properties are significantly influenced by temperature-induced phase changes. In this study, temperature changes and geometric deviations of lenses were studied with respect to heating, pressing, and cooling times and the heat capacity of the heater used. A 3D model was designed for the heating, pressing, and cooling steps, and heat transfer was subjected to numerical analysis considering the specific heat of glass and the temperature dependence of thermal conductivity. Lens molding temperature conditions were then analyzed with the heat capacity of the lens molding heating system. Lens molding conditions were derived by analyzing lens temperatures with respect to heating and cooling capacities at each process step.

Citations

Citations to this article as recorded by  Crossref logo
  • Precision glass aspherical lens manufacturing by compression molding: a review
    Xiaohua Liu, Jian Zhou, Bo Tao, Yang Shu, Zexin Feng, Shih-Chi Chen, Yingying Zhang, Allen Y. Yi
    Light: Advanced Manufacturing.2026; 7: 1.     CrossRef
  • A Study on Temperature and Stress Distribution in a Lens under Multi-Stage Cooling Conditions in Progressive Glass Molding Processes
    Ji Hyun Hong, Jeong Taek Hong, Dong Yean Jung, Young Bok Kim, Keun Park, Chang Yong Park
    Journal of the Korean Society for Precision Engineering.2025; 42(2): 157.     CrossRef
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A Numerical Investigation of Heat Transfer Characteristics with Varying Film Cooling Hole Shapes for Gas Turbine Blade Cooling
Chan Hyeok Park, Sajan Tamang, Hwabhin Kwon, Jaemun Choi, Heesung Park
J. Korean Soc. Precis. Eng. 2022;39(6):443-450.
Published online June 1, 2022
DOI: https://doi.org/10.7736/JKSPE.022.018
Recently, film cooling has been continuously studied to increase the efficiency of gas turbines. A turbine inlet temperature increase occurs as a way to improve the efficiency. However, it is essential to improve the cooling performance of the blade surface because of the melting point of the part. In this paper, a side hole shape wherein a general cylinder hole and two auxiliary holes are combined, is proposed to improve the film cooling efficiency, and the blowing ratio was set to 0.4, 0.8, 1.2, and 2.0. When side hole was applied, the vortex interference at the hole entrance occurred less than that of the cylinder hole. That is, the flow rate of the coolant adsorbed to the surface increased to improve the cooling performance. In conclusion, compared to the cylinder hole, the cooling efficiency of the shape to which the side hole was applied was excellent, and in particular, the average area cooling efficiency with spanwisely designed side holes improved by 83%.
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