Chemically strengthened glass has recently gained attention for use in mobile device display covers due to its enhanced mechanical properties. However, cutting chemically strengthened glass poses challenges because of its high surface compressive stress, derived from the ion exchange between Na+ and K+ during the strengthening process. To address this, we propose an efficient method for cutting chemically strengthened glass by integrating electrochemical discharge (ECD) and grinding processes. The ECD process helps alleviate surface compressive stress through reverse ion exchange, while the grinding process helps mitigate compressive stress on the bottom surface without flipping the glass. Chemical composition analysis of the cross-section of glass cut along the line treated by the ECD process revealed that this method can induce reverse ion exchange on both the upper and bottom surfaces of chemically strengthened glass. Furthermore, nano-indentation hardness tests conducted on the cross-section demonstrated that the subsurface hardness could be reduced by the ECD process, indicating a relaxation of the surface compressive layers. It has also been proven that chemically strengthened glass can be successfully cut using this method, suggesting it offers a viable solution for efficient glass cutting.
In this paper, the relationship between various physical and chemical dynamics included in a gas cutting process was analyzed and a mathematical model was presented. To express the gas cutting process in a formula that could reflect the physics and chemical reaction dynamics, the entire process was classified into three stages: flame spurt, metal oxidation, and metal oxide melting. Flame spurt is caused by combustion of fuel gas and oxygen. It was modeled through fluid dynamics, chemical species transport, and reaction kinetics. Metal oxidation was modeled as a chemical reaction of surface oxidation and oxide growth based on temperature and concentration of species of the metal surface obtained through flame and cutting oxygen spurt results. Finally, the melting of metal oxide was expressed as a rate equation based on melting conditions, heat flux obtained in the previous two stages, and changed properties of the metal. The presented mathematical model could analyze dynamic relationships for each stage of a gas cutting process and connect them into one process. Results of this study can be used as basic data for future finite element analysis and simulations.
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A Comprehensive Review on Flame Scarfing of Steel Slabs: Fundamentals, Challenges, Evolution, and Future Jin Gao, Fengsheng Qi, Zhongqiu Liu, Sherman C. P. Cheung, Baokuan Li, Deqiang Li steel research international.2025;[Epub] CrossRef
There are no known studies on the changes in walking ability in patients with transfemoral amputations returning to daily activities after prosthetic gait training. The ability to walk after discharge may vary depending on an individual’s physical, psychological, and social factors. This study compared spatiotemporal variables and lower limb coordination ability at the end of training and one year after the end of training in seven unilateral transfemoral amputees and analyzed the factors affecting walking ability. The study results confirmed that there was no significant difference in spatiotemporal parameters such as walking speed and lower limb coordination ability after one year of training, and walking ability was well maintained after training. Five out of seven (71.4%) participants in this study returned to work, and there was a strong correlation between employment and gait improvement (r = 0.806, p < .05). In conclusion, activities such as social participation, employment, and exercise were very important factors in maintaining and improving an individual’s walking ability. The findings are intended to be used as basic data to provide guidelines for maintaining the health of lower limb amputees.
Social interest in the 4th industry, intelligent factories, and smart manufacturing is continually growing along with the core technologies like big data and artificial intelligence, which can generate meaningful information by collecting and accumulating sensor data. Demand for industrial automation equipment is increasing worldwide due to the efforts needed to modernize manufacturing facilities, reduce automation and cycle time, and improve quality. Currently, the majority of research is focused on the development of automation facilities and improving productivity. The research on the contents of real-time data considering the characteristics of the cutting machine plasma machine is insufficient. In this study, based on the current data measured according to cutting current and cutting speed, a reference value for cutting quality is presented and the optimal process parameter has been selected. A model for predicting cutting quality by introducing the Mahalanobis Distance Method is presented. An attempt has been made to derive selection and optimal cutting process variables. Based on the predictive model, threshold values were specified and used in real-time data to consider the correlations between multivariate variables and evaluate the degree of scattering around the average of specific values of each variable. Also, process parameters suitable for surface roughness were calculated.
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A quantitative diagnostic method of feature coordination for machine learning model with massive data from rotary machine Yoonjae Lee, Byeonghui Park, Minho Jo, Jongsu Lee, Changwoo Lee Expert Systems with Applications.2023; 214: 119117. CrossRef
Silicon nanoparticles: fabrication, characterization, application and perspectives Taeyeong Kim, Jungchul Lee Micro and Nano Systems Letters.2023;[Epub] CrossRef
Feature selection algorithm based on density and distance for fault diagnosis applied to a roll-to-roll manufacturing system Hyogeun Oh, Yoonjae Lee, Jongsu Lee, Changbeom Joo, Changwoo Lee Journal of Computational Design and Engineering.2022; 9(2): 805. CrossRef
Impact of Sensor Data Characterization with Directional Nature of Fault and Statistical Feature Combination for Defect Detection on Roll-to-Roll Printed Electronics Yoonjae Lee, Minho Jo, Gyoujin Cho, Changbeom Joo, Changwoo Lee Sensors.2021; 21(24): 8454. CrossRef
Many countries are trying to overcome global warming due to greenhouse gas emissions, such as CO₂. In particular, the regulation on CO₂ emissions of internal combustion engine vehicles has become strictly important. Thus, the automobile companies are putting more effort for improving the manufacturing of the battery, which is the main power supply of electrical vehicles. In the electrode cutting process, laser cutting has been actively discussed to solve problems originating from the conventional electrode cutting processes. However, there is a lack of research considering the effect of thickness of the active material on laser cutting. In this paper, the effect of thickness of the active material on laser cutting of electrodes is analyzed. First, the cut electrodes are observed through a scanning electron microscope (SEM). Next, the kerf width and clearance width of the electrodes are measured and compared at the same laser parameter. The kerf width and clearance width of relatively thick electrodes are narrowly formed. Finally, the cutting quality of the electrode is compared. A uniform cut edge is observed as the scanning speed increases.
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Comparison of laser processability for LiFePO4 cathode material with nanosecond and femtosecond laser Jaegeun Shin, Juhee Yang, Dongkyoung Lee Journal of Science: Advanced Materials and Devices.2024; 9(3): 100753. CrossRef
Gait analysis is the best objective measurement tool for monitoring rehabilitation. However, it has limitations to evaluate gait recovery. Previous studies have evaluated the effect of gait training using continuous relative phase. The objective of this study was to determine the effect of gait recovery by rehabilitation gait training on lower limb coordination. We analyzed spatio-temporal parameters and CRP values of hip and knee joints based on gait analysis data obtained by 3D motion analysis system at 15 days intervals in 24 uni-lateral transfemoral amputees participated in IRP. Our results revealed that walking velocity of uni-lateral transfemoral amputees who participated in the program during a mean of 107.1 days was 49.2% faster than that at initial stage. The walking velocity showed a 46% increase at the end of 30 days after training. In gait coordination, values of CRP-RMS and CRP-SD were increased and maintained in-phase pattern. CRP showed symmetry in both limbs at the end of 90 days after training. Therefore, CRP is a significant factor in the gait recovery process. Effects of various rehabilitation training methods can be determined through CRP analysis.
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A Comparative Study of the Effects of Augmented Reality Application on Movement Accuracy and Subjective Satisfaction in Rehabilitation Training for Individuals with Lower Limb Amputations Yunhee Chang, Jungsun Kang, Hyeonseok Cho, Sehoon Park Applied Sciences.2025; 15(12): 6703. CrossRef
Changes in Gait Characteristics after Completion of Prosthetic Gait Training in Patients with Unilateral Transfemoral Amputation: Follow-Up after 1 Year Bo Ra Jeong, Gyoo Suk Kim, Yun Hee Chang Journal of the Korean Society for Precision Engineering.2022; 39(11): 849. CrossRef
In this study, beam divergence through an optical fiber has been controlled through shaping of the optical fiber tip using a CO₂ laser, which make the beam divergence smaller than the conventional diamond wheel cleaving method. Precise length cleaving of an optical fiber inserted in a ferrule using a femtosecond laser has also been investigated with respect to changes of the laser pulse energy. A ribbon fiber composed of 12 optical fibers could be cut precisely at different lengths in a micrometer scale.
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Fabrication of Lensed Optical Fibers for Biosensing Probes Using CO2 and Femtosecond Lasers Ki-Dong Lim, Hun-Kook Choi, Ik-Bu Sohn, Byeong-Ha Lee, Jin-Tae Kim Applied Sciences.2021; 11(9): 3738. CrossRef
To evaluate the quality of the cross section of Ni alloy thin plate cut by laser, we have proposed an analysis method using SEM image to measure surface roughness of cross section. The surface roughness of the cut area of the thin plate is considerably difficult to analyze using conventional measurement technique such as profile measurement with a probe. When the SEM image is used, the roughness value can be collected quantitatively while judging the surface status qualitatively. A Hastelloy C-276 thin plate with a thickness of 50 μm coated with HTS was cut by Nd:YAG laser, and the state of the cross section was analyzed by applying the proposed method in this research. The optimum laser cutting process condition could be found for the lowest surface roughness.
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