Glass Molding Process (GMP) is an effective method for producing precise optical elements such as lenses. This simulation study aimed to predict the distribution of temperature and stress within a lens during a multi-stage cooling process of GMP. To develop an accurate simulation model including molds and lens, thermal contact conductance and boundary conditions were determined by analyzing experimental and simulation results. The developed model was used to investigate changes in temperature and maximum principal stress within the lens, considering variations in cooling time, speed, and method at each cooling stage. Simulation results indicated that trends of maximum temperature difference and maximum principal stress within the lens were consistent over time. Results also showed that the maximum principal stress inside the lens increased significantly with additional cooling after uneven temperature distribution caused by a relatively short cooling time. Compared to simulation results of the cooling process involving contact only with bottom surface of the mold, contact cooling with both top and bottom surfaces showed decreased residual stress at the end of cooling and maximum temperature difference within the lens. However, the maximum principal stress could be higher during the cooling process involving both surfaces.
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Optimization of heating and molding temperatures in multi‐station glass molding for a meniscus aspheric lens Jian Zhou, Baocheng Huang, Shihu Xiao, Lihua Li International Journal of Applied Glass Science.2026;[Epub] CrossRef
Recent advancements in additive manufacturing (AM) have made it possible to create compact heat exchangers (HXs) with complex geometries. This study introduces a new approach that uses Triply Periodic Minimal Surface (TPMS)-based designs for HXs. Mathematical filtering techniques are incorporated to optimize the local morphology changes. The goal of the proposed mathematical filtering method is to improve the flow characteristics and heat exchange capability of TPMS HXs by modifying the structure’s morphology at the inlet and outlet regions. This modification facilitates flow selection and reduces pressure drop. The HX design includes cylindrical flow domains at the inlet and outlet regions. Three different HX designs with varying inlet/outlet domains (through-hole, half-hole, and taper-hole) were fabricated using polymer AM and DLP 3D printing. These designs were then tested for pressure drop. Among the three designs, the taper-hole configuration showed the best flow characteristics, with a 50% reduction in pressure drop compared to previous studies. The taper-hole design was then replicated using metal AM technology, resulting in a 70-125% improvement in heat exchange capacity compared to previous studies.
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Multifunctional gradations of TPMS architected heat exchanger for enhancements in flow and heat exchange performances Seo-Hyeon Oh, Jeong Eun Kim, Chan Hui Jang, Jungwoo Kim, Chang Yong Park, Keun Park Scientific Reports.2025;[Epub] CrossRef
The purpose of this study is to propose a better contact surface pattern of a heat radiating block in a progressive GMP (Glass Molding Process) heating assembly. In this study, a simulation model based on FEM was developed to perform a thermal analysis for the heating assembly. It was verified by comparing experimental results. The temperature distribution on the heating block surface and heating energy consumption was analyzed with the change of contact surface pattern and area of a heat radiating block. The considered pattern on the contact surface was cross (+) and straight (-) shape. The contact area ratio was changed from 16 to 100%. The simulation results show that the heating energy consumption increased to reach a target temperature with the increase of contact area ratio. The straight-shaped patterns on a heat radiating block presented more uniform temperature distribution on the mold heating surface than the cross shaped surface, whereas it resulted in a slightly higher energy consumption of up to 9%. This study shows that the contact surface pattern on a heat dissipating block can control the temperature distribution on the mold heating surface.
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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
A Study on Numerical Analysis for Determination of Glass Molding Process Conditions for Glass Lenses Jaehun Choi, Sajan Tamang, Heesung Park Journal of the Korean Society for Precision Engineering.2024; 41(3): 207. CrossRef
Injection molding is one of most widely-used polymer processing technologies in which hot polymer fills a mold cavity, and is solidified during the subsequent cooling process. In the mold filling stage, the mold temperature should be high to improve flow characteristics, and low to reduce cooling time during the cooling stage. To fulfill these objectives, rapid mold heating technology has been developed to raise mold temperature, without significant increase in cycle time. While the conventional rapid heating technologies required dedicated facilities such as steam heating or high-frequency induction heating system and has a limitation in uniform heating, the purpose of this study was to develop a facile and conformal mold heating unit that uses a carbon nanotube (CNT) film heater. The CNT film heater was used to heat a curved mold with high temperature uniformity, by maintaining uniform distance from the mold surface. The developed conformal heating technology was then applied to a singly curved mold and a multiply curved mold. Considering that the resulting temperature uniformity is superior to the conventional oil heating, the conformal mold heating technology using the CNT film heater can be used to improve part quality and productivity in various molding processes.
Research on the application of additively manufactured polymer (AMP) to the conventional manufacturing process is underway. In this study, an additively manufactured die-set (AMDS) was used and applied to the warm forming of the magnesium alloy. Heat transfer and coupled temperature-displacement analysis were conducted in the V-Bending and UBending processes to study the applicability of the AMDS to the warm-forming process of the magnesium alloy sheet (AZ31B). A heat transfer experiment was conducted to determine the thermal contact conductance between the AZ31B material and two types of die-set, the metal and AMP. V-Bending and U-Bending experiments were conducted at 373 and 423 K; reduction in temperature between metal die-set and the additively manufactured polymer die-set were compared. The springback after the bending process with different initial temperatures and die materials was investigated. The simulation model showed good agreement. The springback of AZ31B was more decreased with the additively manufactured polymer die-set than with the metal die-set. The stress of the additively manufactured polymer die-set in the bending process was very small. It was confirmed that in the AZ31B material, the additively manufactured polymer die set helps increase the formability and decrease springback by keeping the temperature of AZ31B better.
Owing to recent advances in additive manufacturing technology, design for additive manufacturing (DfAM) has been used to overcome design limitations due to constraints in traditional manufacturing processes. In this study, we applied DfAM technology to design lightweight and consolidated vacuum grippers for inspection equipment. We proposed a consolidated design to reduce manufacturing time and costs, which previously encompassed assembling eleven components. Topology optimization was used to reduce part weight while maintaining structural rigidity and safety, and two optimization models were designed: two-piece and one-piece models. Based on these optimized geometries, the internal vacuum paths were designed in a curved shape to enhance adsorption characteristics. Numerical simulations were conducted to evaluate the structural performance and flow characteristics of the initial design and the two optimization models. The pressure drop of the one-piece model, which was the best design, was reduced to 1/8 of the initial design and the structural safety factor was predicted to be 6.37. This final design was then additively manufactured by a digital light processing type 3D printer and the weight of the resulting parts was reduced from 12.94 to 2.08 g. Experimental observation found that the additively manufactured vacuum gripper showed enhanced absorption performance compared to the initial design.
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A Study on Improvement of Flow Characteristics of TPMS Heat Exchanger based on Mathematical Filtering Seo-Hyeon Oh, Jeong Eun Kim, Ji Seong Yun, Do Ryun Kim, Jungwoo Kim, Chang Yong Park, Keun Park Journal of the Korean Society for Precision Engineering.2024; 41(7): 541. CrossRef
A Study on Injection Mold Design Using Topology Optimization Mi-Jin Kim, Jae-Hyuk Choi, Gyeng-Yun Baek Journal of the Korean Society of Manufacturing Process Engineers.2022; 21(4): 100. CrossRef
The purpose of this study was to design a sledge frame for para ice hockey in which an athlete sits and plays on a sledge. A sledge comprises a bucket, a blade carrier, and a frame. A sledge frame is usually fabricated by welding a number of pipes, and thus its structural safety is degenerated at the welded joints. In this study, the sledge frame was redesigned using the principle of DfAM (Design for Additive Manufacturing), to reduce the frame weight as well as to have sufficient structural safety. As an application of DfAM, the part consolidation was performed for six joints from which the number of welding spots was reduced to 56% (From 16 to 9). Among the resulting four consolidated joints, topology optimization was performed for three joints to reduce their weight while maintaining higher structural stiffness and safety. As a result, the structural stiffness and safety of the joints improved remarkably, and the resulting frame weight was reduced by 20% (From 1.66 to 1.34 kg). This weight reduction with structural enhancement is expected to improve athletes’ performance and safety in para ice hockey games.
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A Study on Improvement of Flow Characteristics of TPMS Heat Exchanger based on Mathematical Filtering Seo-Hyeon Oh, Jeong Eun Kim, Ji Seong Yun, Do Ryun Kim, Jungwoo Kim, Chang Yong Park, Keun Park Journal of the Korean Society for Precision Engineering.2024; 41(7): 541. CrossRef
Additive Manufacturing of a Release Agent Injection Manifold for Hot Forging Hak-Sung Lee, Min-Kyo Jung, Eun-ah Kim, Soonho Won, Do Wock Chun, Taeho Ha Journal of the Korean Society for Precision Engineering.2021; 38(9): 675. CrossRef
Analysis on the Warm Bending Process of Magnesium Alloy Sheet Using Additively Manufactured Polymer Die-Set Hyung-Won Youn, Jun-Hyun Kyeong, Keun Park, Chang-Whan Lee Journal of the Korean Society for Precision Engineering.2021; 38(10): 775. CrossRef
Lightweight Design of a Vacuum Gripper for Inspection Equipment Using Topology Optimization Euddeum Cha, Tae-Young Kim, Taeho Ha, Keun Park Journal of the Korean Society for Precision Engineering.2021; 38(9): 683. CrossRef
The purpose of this study was to develop an efficient mold heating technology by an embedded heating unit. To localize the heating effect in the mold core and prevent heat transfer to surrounding mold plates, the core module with embedded heating unit was assembled to a mold plate in a detachable manner. The detachable core module was then separated from the mold plate when the mold was opened, and thus could be rapidly heated by the embedded heater. The heated core contacted with the mold plate when the mold was closed, and could be cooled by heat conduction to the mold plate of which thermal inertia was much larger than that of the core module. To verify thermal efficiency of the proposed structure, heat transfer simulation was performed with an experimental validation. Mold filling simulation was also performed to investigate the effect of mold heating on improving flow characteristics through a thin and narrow channel. Injection molding experiments were also conducted by adopting the proposed embedded heating module.
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Analysis of Rapid Heating Performance in Multi-Layered Injection Mold System for CNT Surface Heating Element Application Hyeon Min Lee, Young Bae Ko, Woo Chun Choi Journal of the Korean Society for Precision Engineering.2022; 39(7): 461. CrossRef
Energy Saving of Rubber Forming by Direct Heating Press Mold Development Young Tae Cho Journal of the Korean Society for Precision Engineering.2022; 39(7): 485. CrossRef
A Study on Conformal Heating of Curved Mold Using CNT Film Heater Seo-Hyeon Oh, Eun-Ji Jeon, Hyeon-Min Lee, Yeong-Bae Ko, Keun Park Journal of the Korean Society for Precision Engineering.2022; 39(7): 469. CrossRef
Conformal Mold Heating and Cooling Using a Carbon Nanotube Film Heater and Additively Manufactured Cellular Metamaterial Jeong-Hee You, Jun-Won Lee, Seo-Hyeon Oh, Keun Park International Journal of Precision Engineering and Manufacturing-Green Technology.2022; 9(6): 1463. CrossRef
A Study on the Heat Transfer Characteristics of a Glass Lens Mold Heating Block according to Design of a Heat Radiating Block Bo Min Seo, Dong Yean Jung, Keun Park, Chang Yong Park Journal of the Korean Society for Precision Engineering.2022; 39(7): 493. CrossRef
The objective of this study was to investigate the effect of heat treatment on electrochemical performance of aluminum (Al)-air battery. We prepared a pure Al and an annealed Al under an annealing environment [a mixture gas of Ar (97%) and H2 (3%)] of 400°C for 1 hr. Based on electron backscatter diffraction analysis of Al at the anode, the relative misorientation of the pristine Al was higher than that of the annealed Al. Electrochemical performances of the pristine Al-air and the annealed Al-air were also compared. The annealed Al-air battery showed slightly higher power density than the pristine Alair battery. These results suggest that annealing with heat treatment is an important process to improve the electrochemical performance of aluminum-air battery.
For 3D printing of high-strength polymers, such as PC (Polycarbonate) and PEI (Polyetheimide), the temperature of the nozzle should exceed the melting temperature of the high-strength materials. At the same time, the temperature of the transfer part, composed of the shaft extruder and the Teflon hose, should be cooled below the glass transition temperature and below the limit temperature of the transfer part. In this study, we analyzed the effect of the flow rate of the cooling fan when the extruder nozzle is heated to 300oC. We compare the natural convection environment, in which the cooling fan is not operated, and the forced convection condition, in which the cooling fan is operated, and analyze the effect on the cooling fan flow rate. The simulation considered the heat transfer in the air and the nozzle, as well as the flow characteristics of the air.
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A Study on the Improving Extrusion Defects in FDM 3D Printers Jun-Seok Do Journal of the Korean Society of Manufacturing Process Engineers.2024; 23(4): 80. CrossRef
Analysis of Correlation between FDM Additive and Finishing Process Conditions in FDM Additive-Finishing Integrated Process for the Improved Surface Quality of FDM Prints Ji Won Yu, Hyung Jin Jeong, Jae Hyung Park, Dong Hun Lee Journal of the Korean Society for Precision Engineering.2022; 39(2): 159. CrossRef
Analysis on the Warm Bending Process of Magnesium Alloy Sheet Using Additively Manufactured Polymer Die-Set Hyung-Won Youn, Jun-Hyun Kyeong, Keun Park, Chang-Whan Lee Journal of the Korean Society for Precision Engineering.2021; 38(10): 775. CrossRef
Indirect Temperature Measurement in High Frequency Heating Systems Alexander Oskolkov, Igor Bezukladnikov, Dmitriy Trushnikov Sensors.2021; 21(7): 2561. CrossRef
This study aims at developing a high temperature extruder for an FDM (Fused Deposition Modeling) type 3D printer that uses engineering thermoplastic filaments. An extruder is a key part of an FDM type printer, in which a filament moves to a heating block and is extruded through a nozzle with a specific diameter. For an appropriate extrusion, the filament should be heated above its softening temperature. Specifically, the filament should not be melted nor softened before it reaches the heating block for appropriate delivery. Hence, the extruder temperature should be carefully controlled to ensure its heating capability as well as its proper delivery. To meet these requirements, thermal-structural finite element (FE) analyses were performed for the prediction of the distributions of temperature and thermal stress. Various extruder designs were then considered to maximize the temperature difference between the nozzle and delivery parts, as well as to ensure structural safety.
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A Study on the Improving Extrusion Defects in FDM 3D Printers Jun-Seok Do Journal of the Korean Society of Manufacturing Process Engineers.2024; 23(4): 80. CrossRef
Optimization Design of Student KSAE BAJA Knuckle Using SLM 3D Printer Young Woo Im, Geon Taek Kim, Hyeon Sang Shin, Kang Min Kim, Bu Hyun Shin, Jong Won Lee, Jinsung Rho Journal of the Korean Society for Precision Engineering.2023; 40(9): 719. CrossRef
Thermal-Fluid Coupled Analysis of the Nozzle Part for the FDM 3D Printers Considering Flow Characteristics of Cooling Fan Chang-Whan Lee, Hyun-Woo Kim, Jea-Hyeong Yu, Keun Park Journal of the Korean Society for Precision Engineering.2018; 35(5): 479. CrossRef
The mold manufacturing is one batch production that the same process does not repeat. The digital model in software is processed with a real mold fabricated in high performance without error. In this study process planning, and machining simulation software are integrated with a smart machine tool for the mold industry. It reduces the operational complexity to four button clicks after dragging and dropping of 3d model data to fabricate multiple-numbers of graphite electrodes. The smart machine tool fabricated 27 graphite electrodes with minimum interference of humans in 35 hours.
Recent use of mobile phones as a multimedia device has increased the development of micro-speaker modules having high quality and a compact size. Micro-speakers use polymer diaphragms fabricated by the thermoforming process. To improve the sound quality, micro-speaker diaphragms are usually designed to contain a number of micro-corrugations. This study investigated the effects of the corrugation depth on the acoustic characteristics of the diaphragm, using finite element (FE) analysis. Structural FE analysis was performed to investigate the stiffness change according to the corrugation depth. Modal FE analysis was used to compare the change in natural frequencies for each case. Harmonic response analysis further investigated the resulting variation in acoustic power. The effects of the corrugation depth on the acoustic characteristics of the diaphragm were discussed by reviewing all the FE analysis results synthetically.
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Design and Analysis of a Novel Microspeaker with Enhanced Low-Frequency SPL and Size Reduction Ki-Hong Park, Zhi-Xiong Jiang, Sang-Moon Hwang Applied Sciences.2020; 10(24): 8902. CrossRef
In this study, we developed a 3D chocolate printer and studied the conditions needed for chocolate printing. Because chocolate is a mixture of cocoa mass, cocoa butter and sugar particles, its properties vary with temperature, and care is required in melting and extrusion. A chocolate supply unit is composed of a heating block and a syringe pump. It is integrated with a 3-axis linear robot. In order to be more accurate than the existing 3D chocolate printer is, the system was configured so that the printing line width became 430 μm. Printing performance was studied according to various parameters. The condition needed for printing lines with a stable width was discovered by the experimental design method and has been confirmed by a 2D line test. These 3D printing experiments showed that it was possible to build a 3D shape with an inclination angle of up to 45° without support. Further, chocolate printing of a 3D shape has been successfully verified with the developed system.
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Quality Characteristics of Jujube Brownie with Jujube Paste Hyeon Sook Lim, Mi Ra Choi, Su In Kim, Gyung Hee Cha Journal of the East Asian Society of Dietary Life.2021; 31(3): 191. CrossRef
Development of a Material Mixing Extrusion Type Chocolate 3D Printer MinSoo Park, HyungJik Jeong, JaeHyuek Moon, JungMuk Lim Journal of the Korean Society for Precision Engineering.2021; 38(2): 145. CrossRef
Ceramic Direct Rapid Tooling with FDM 3D Printing Technology Geun-Sik Shin, Hyun-Kyu Kweon, Yong-Goo Kang, Won-Taek Oh Journal of the Korean Society of Manufacturing Process Engineers.2019; 18(7): 83. CrossRef
Thermal-Structural Coupled Numerical Analysis for Design of High-Temperature Extruder of FDM 3D Printers Da-Yeon Shin, Hyun-Joong Lee, Chang-Whan Lee, Keun Park Journal of the Korean Society for Precision Engineering.2018; 35(3): 341. CrossRef
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