To reduce the use of fossil fuels, the adoption of battery electric vehicles (BEVs) using lithium-ion batteries has been increasing in internal combustion engine alternatives. Accordingly, significant efforts have been made to improve the manufacturing process of lithium-ion batteries within electric vehicles. In particular, the cutting process of lithium-ion batteries has been actively discussed as it is closely related to battery performance. Laser-based cutting enables a more precise and sustainable manufacturing process. The laser ablation threshold has been investigated in many studies to achieve high-precision laser processing. While laser parameters and ambient conditions have been examined to determine the laser ablation threshold, studies focusing on the effect of relative humidity remain insufficient. Thus, this study investigated the laser ablation threshold of aluminum foil under varying relative humidity conditions. First, a laser interaction chamber was fabricated to control the relative humidity during experiments. A scanning electron microscope (SEM) was then used to observe laser ablation craters and analyze the threshold. The variation of the laser ablation threshold with relative humidity revealed changes in the interaction between the laser and aluminum foil depending on the humidity level.
The demand for high-speed processing and big data has accelerated the adoption of three-dimensional integrated circuits (3D ICs), where interposers serve as essential components for chip-to-chip connectivity. However, silicon interposers using the through-silicon via (TSV) technology have structural limitations. As alternatives, glass-based interposers employing the through-glass via (TGV) technology are gaining attention. This study explored the fabrication of via holes in glass substrates using the selective laser etching (SLE) process. A spatial light modulator (SLM) was used to generate donut- shaped bessel beams by inserting an image pattern without relying on phase modulation. The machinability of via holes fabricated with these beams was compared to that of holes formed using phase-modulated beams. Effect of pulse energy on taper angle was also investigated. Hourglass-shaped holes were observed at lower pulse energies. However, taper angles approaching 90° were observed at higher energies, indicating an improved verticality.
The propulsion system of a projectile is very important for the aerospace industry. To perform space exploration mission, controlling position and posture of the projectile in the terminal stage is very important. In this study, a new lateral thrust system is proposed to control the position and posture of the projectile at the terminal stage. Based on nozzles in a lateral thruster, a high-speed projectile can instantly change its position and posture. After changing its position and posture, reverse thrust is generated to control unnecessary movements for stabilizing. Based on various tests, the operation and performance of the nozzle opening device (NOD) of the separation mechanism were validated. As a result, excellent reproducibility was confirmed with standard deviation of 0.057 ms for the time from the end of igniter operation to the start of NOD separation. The internal pressure of the chamber and NOD separation time were inversely proportional to each other with a linear relation. The internal pressure of the chamber and flight speed of NOD were also proportional to each other. The flight speed of NOD was 37.53 m/s at the maximum expected operation pressure (β), 30.26 m/s at 0.5 β, and 17.05 m/s at 0 psi.
This study presents results of Computational fluid dynamics (CFD) analysis conducted to evaluate performances of various functional products developed for smart bathroom systems. The primary objective was to analyze the efficiency of space heating, direct drying, and dehumidification functions in a winter bathroom environment. Representative bathroom models in South Korea were selected and detailed CFD simulations were performed on these models. Results showed that bathtub models exhibited higher efficiency overall in space heating and dehumidification than shower booth models. This was attributed to differences in bathroom structure and internal air flow. Additionally, the direct drying function showed higher efficiency in bathtub models, determined by the placement of air outlets and inlets. This study provides essential foundational data that can contribute to the design and enhancement of smart bathroom systems' functionality, offering valuable insights for the development of optimized smart bathroom products.
Recent advancements in science and technology have enabled even microsatellites to perform various high-level tasks. As the range of missions that satellites undertake expands, even microsatellites now require thrust systems for orbit adjustment and collision avoidance. In such satellite applications, sizes and weights of all electrical components and propulsion systems are restricted, emphasizing the importance of miniaturization and weight reduction. Research is ongoing in various methods to address these needs. To solve these challenges, this study proposed a design model for miniaturizing and lightening both Anode Power Module (APM) and gas supply system. The APM utilizing an LLC resonant converter achieved an efficiency of up to 86%. An evaluation of flow control characteristics of the proposed gas supply device showed that the flow control error was less than 2.3%, indicating effective results. A thermal mass flow sensor was developed to measure the flow of gas. Temperature characteristics derived from experiments were analyzed to assess their applicability to electric thruster systems for satellites.
Chemical mechanical planarization (CMP) is an essential polishing process in semiconductor manufacturing. Advances in memory technology, including increased capacity and performance, have increased the importance of electronic packaging. In heterogeneous integration, the interposer acts as an important intermediary between the logic die and the substrate, solving numerous I/O bump problems in high-bandwidth memory (HBM) and logic chips. Traditionally, board-to-memory connections were made through wire bonding, which required additional space for wire connections and introduced latency due to extended signal transmission paths. A through-type approach has emerged as a solution that can significantly reduce waiting time and installation space by improving space efficiency and enabling vertical connections without extending wiring. Due to these new approaches, the importance of CMP is reemerging. Implementation of this important process requires precise control of the CMP dishing/protrusion of bonding surfaces. Improper selection of Cu pad dishing/protrusion can cause problems such as increased RC delay time and signal short circuit in the wiring. In this paper, we proposed a strategy to control dishing using CMP, especially for Through-glass-via (TGV).
Automatic transmissions, which have the advantages of compact structure and smooth shifting, are installed in various vehicles with engines and hybrid power sources. Research and development are continuously being conducted to improve power and fuel efficiency. In this study, the influence of helix direction and helix angle of the planetary gear set on thrust-bearing power loss in an automatic transmission was analyzed. A sample automatic transmission model was constructed to analyze the axial load and bearing relative rotation speed, which are the main factors in thrust-bearing power loss. The relative rotation speed of the bearing was analyzed using the sample model, and the thrust-bearing load in the axial direction was analyzed according to the helix direction of the planetary gear set constituting the model and the helix angle of the planetary gear set. The power loss occurring in thrust-bearing was derived using the analysis results of relative rotational speed and load, and the influence of the helix direction and helix angle of the planetary gear set was analyzed.
Currently digital transformation has a huge impact on human lives. Digital transformation does not just mean a transformation of a (non-) physical element to a digitally identifiable element. It focuses on the utilization of digital technology for transforming (improving) procedures or routines of business and operation. The manufacturing industry has been adopting the most recent digital technology, and lots of digital data are being created. To utilize the stored data, data analysis is essential. Because the manufacturing data is created in a different format at every manufacturing step, the integration of the data is always the bottleneck of the data analysis. Querying of the right data at the proper time is fundamental for high-level data analysis. The digital thread is introduced to provide the inter-reference of digital data based on a context. This paper proposes a digital thread framework for the machining process. The context of the proposed framework consists of the questions of how the product will be machined, how it is (was) being produced, and how it was made. A prototype software was developed to verify the proposed framework by implementing the creating, storing, and querying modules for simulation, monitoring, and inspection data.
Citations
Citations to this article as recorded by
A Review of Intelligent Machining Process in CNC Machine Tool Systems Joo Sung Yoon, Il-ha Park, Dong Yoon Lee International Journal of Precision Engineering and Manufacturing.2025; 26(9): 2243. CrossRef
Knee contact forces and knee stiffness are biomechanical factors worth considering for walking in knee osteoarthritis patients. However, it is challenging to acquire these factors in real time; thus, making it difficult to use them in robotic rehabilitation and assistive systems. This study investigated whether trained deep neural networks (DNNs) can capture the biomechanical factors only using kinematics during gait, which is possible to measure via sensors in real time. A public dataset of walking on the ground was analyzed through biomechanical analysis to train and test DNNs. Using the training dataset, several DNN topologies were explored via Bayesian optimization to tune the hyperparameters. After optimization, DNNs were trained to estimate the biomechanical factors in a supervised manner. The trained DNNs were then evaluated using two new datasets, which were not used in the training process. The trained DNNs estimated the biomechanical factors with a high level of accuracy in both types of test datasets. Results confirmed that DNNs can estimate the biomechanical factors based on only kinematics during gait.
This paper proposed the simulation model of the servo system with three-stage reducer and presented the result of frequency analysis of the servo system considering backlash ratios and motor input voltage. By virtue of this work, we realized that if the motor input voltage of the system was large, the influence of each stage backlash ratio could be minimized or removed. Besides, we also found that if the motor input voltage was small, this created an optimal backlash ratio combination which could maximize the anti-resonance and resonance frequency of the servo system. This paper could be useful for determining each stage backlash ratio in designing a three-stage geared servo system with fast response.
A femtosecond laser is used in various fields such as microscale machining, OLED repair, micro 3D structure fabrication, and eye surgery. Particularly, because of non-thermal property, ablation and ablation threshold are the most representative characteristics of femtosecond laser. The ablation system is accompanied by many optics, stage, or gantry. In the case of the gantry, an ordinary optic system delivers a beam where mirrors and lens are required. If the gantry moves to the sample, external stimulation such as vibration will occur. Vibration has an influence on optics such as transforming beam path and becomes an error that decreases accuracy, precision, and spatial resolution. Generally, Fiber Optic Beam Delivery System (FOBDS) is used to solve this issue. But in the case of the femtosecond laser, FOBDS is incompatible. Recently, another FOBDS model that is compatible with the femtosecond laser has been developed. In this paper, the ablation threshold was obtained by FOBDS and femtosecond laser. The results present a possibility of ablation without external stimulation.
Citations
Citations to this article as recorded by
257 nm Deep UV Femtosecond Laser Ablation with Minimized Crack and Chipping on Display Ultra-Thin Glass Kwangwoo Cho, Junha Choi, Changdeok Ko, Muhyun Kim, Joohan Lee, Eunhyang Eom, Sung-Hak Cho International Journal of Precision Engineering and Manufacturing.2024; 25(2): 271. CrossRef
This paper describes a new design method for constructing a heat exchanger computational model comprising TPMS (Triply Periodic Minimal Surface) core structures. These TPMS-Based core structures cannot be designed using the existing CAD systems, especially for heat exchangers with a high level of geometric complexity. This paper introduces a new implicit design algorithm based on the VDF (Volumetric Distance Field) calculation. All geometric components, including the TPMS-based core structures, heat exchanger exterior shapes, a set of parts for inlets and outlets, are represented by the VDF in a given design area. This enables the efficient design of computational models for the arbitrary-complex heat exchangers. The proposed design method extends the 2D flow pattern of the existing CHE into the 3D flow pattern, providing high heat transfer efficiency and low-pressure drop. Investigation of the design results and manufactured prototypes using the AM (Additive Manufacturing) technology showed that the proposed TPMS CHE design method can open a new paradigm for generating high-performance next-generation CHEs which cannot be designed and manufactured with the existing CAD and CAM technologies.
Citations
Citations to this article as recorded by
Analysis of Convective Heat Transfer Coefficient of Double-wall Gyroid TPMS under Constant Surface Temperature Conditions Sohyun Park, Jihyun Sung, Dahye Kim, Kunwoo Kim Journal of the Korean Society for Precision Engineering.2025; 42(12): 1071. CrossRef
A Study on Design and Fabrication Characteristics of TPMS Structures Hyun Kim, Kwang-Kyu Lee, Dong-Gyu Ahn Journal of the Korean Society of Manufacturing Process Engineers.2024; 23(2): 52. CrossRef
Triply Periodic Minimal Surface Structures: Design, Fabrication, 3D Printing Techniques, State‐of‐the‐Art Studies, and Prospective Thermal Applications for Efficient Energy Utilization Mohamed G. Gado, Oraib Al‐Ketan, Muhammad Aziz, Rashid Abu Al‐Rub, Shinichi Ookawara Energy Technology.2024;[Epub] CrossRef
A Study on the Dissolution Characteristics of 3D Printed Tablet with Lattice Structures Sang Hoon Lee, Seung Min Oh, Seo Rim Park, Seok Kim, Young Tae Cho Journal of the Korean Society for Precision Engineering.2023; 40(8): 633. CrossRef
Design analysis of the “Schwartz D” based heat exchanger: A numerical study Reza Attarzadeh, Marc Rovira, Christophe Duwig International Journal of Heat and Mass Transfer.2021; 177: 121415. CrossRef
Rotary tables are often used to fix and support work-pieces in machine tools. Because the deformation of the rotary table is known to significantly affect the precision in the work of the machine tool, it is very important to accurately predict the static displacements of the rotary table subjected to internal and external loads. This paper deals with modeling and experimental verification of the static displacements of a large-size rotary table supported by a thrust cylindrical roller bearing (T-CRB) and a double row cylindrical roller bearing (D-CRB). To this end, a rotary table model was developed along with the quasi-static models for T-CRB and D-CRB. The equilibrium equation of the rotary table was derived, and solved one by one in the looping manner, to overcome its statically indeterminate characteristics. The proposed modeling method was verified by means of comparing to the experimental results. Finally, an extensive simulation was carried out to investigate the deflection of the rotary table subjected to cutting forces.
Citations
Citations to this article as recorded by
Absolute Inductive Angular Displacement Sensor for Position Detection of YRT Turntable Bearing Yangyang Wang, Yi Qin, Xihou Chen, Qifu Tang, Tianheng Zhang, Liang Wu IEEE Transactions on Industrial Electronics.2022; 69(10): 10644. CrossRef
Study on the Guide Rail Deformation in Linear Roller Bearings Subjected to External Loading Jun-Ho Heo, Sun-Woong Kwon, Seong-Wook Hong Journal of the Korean Society for Precision Engineering.2019; 36(1): 79. CrossRef
Recently, a Total Ankle Arthroplasty (TAA) has been commonly used when no other options are available for patients with severe arthritis at the ankle joint. But bone resorption, aseptic loosening, instability, malalignment and fractures are generally known as the main reasons of TAA failures. Those TAA which have been designed up until now are generally based on the morphological and kinesiological characteristics of the ankle joint. They are adjusted by the ankle joint size of Westerners, although both the morphological and mechanical (strength) characteristics of the ankle joints of Asian are important in the development of a TAA suitable to Asians. Little information about the morphological and mechanical characteristics of the ankle joint of Asians is available for the development of a TAA suitable to Asians. The purpose of this study was, therefore, to analyze the morphological and mechanical characteristics of the ankle joints of Asians. Computed tomography data obtained from 50 patients (mean age: 64.14 ± 9.34 years) were analyzed.
Citations
Citations to this article as recorded by
Evaluating the validity of lightweight talar replacement designs: rational models and topologically optimized models Yeokyung Kang, Seongjin Kim, Jungsung Kim, Jin Woo Lee, Jong-Chul Park Biomaterials Research.2022;[Epub] CrossRef
In this study, we propose a fabrication method of three-dimensional complex shape polydimethylsiloxane microstencils. Three-dimensional complex shape polydimethylsiloxane (PDMS) microstencils were fabricated by an air-knife system and PDMS casting form preparing master mold by photolithography, diffuser lithography and polyurethane acrylate (PUA) replication. PDMS microstencils shape was a production of the hemispherical and quadrangular pyramid. When the prepolymer of PDMS was spin-coated onto the three-dimensional complex shape master mold, a thin layer of prepolymer remained on top of the master"s structure and consequently prevented formation of perforated patterns. This residual layer was easily removed by the air-knife. The air-knife system was controlled by the flow rate of N2 gas and conveying speed of the master mold. Results revealed the fabricated three-dimensional complex shape PDMS microstencils, could be useful for application of three-dimensional cell culture device.
Citations
Citations to this article as recorded by
Review on Microstencil Lithography Technologies Jin Ho Choi, Hye Jin Choi, Gyu Man Kim Journal of the Korean Society for Precision Engineering.2018; 35(11): 1043. CrossRef
First
Prev
