MXene is one of the most fascinating 2D materials owing to its great electrical properties and unique performance. Among various application areas, the performance of organic material adsorption has been highlighted with the growing interest in the biocompatible applications of MXene. Although previous research revealed that the huge surface area of this 2D nanomaterial could lead to superior organic material adsorption performance, surface functional groups were usually controlled by changing the pH, and the MXene was generally produced by HF etchant. In this study, a surface modification method of Ti₃C₂Tx MXene film was proposed to enhance organic material adsorption by irradiating the pulsed plasma electron beam (EB). Methylene blue (MB)-dispersed DI water was prepared, and pristine MXene was prepared at pH 7. The MB concentration was only reduced by 20% by pristine MXene. However, EB-treated MXene adsorbed about 75% of the MB within 20 min and over 90% within 80 min when the MXene film was ground to powder form. The results showed that the increased surface area and formation of hydrophilic functional groups successfully modified MB adsorption following EB irradiation under optimal processing conditions.
In this study, the production process of eccentric head bolts that fasten flanges for water supply pipe connections, which can only be achieved through the cold forging process, was improved. For axial forging, forming analysis was performed for a 200-ton header machine to check the raw material specifications, forming load, and metal flow improvements suitable for forming. The analysis found that the forging of high-strength bolts of M14×65 ㎜ with eccentric heads was possible under the maximum load condition of 137.2 tons with low carbon boron steel of ø13.8×89.7 ㎜ and 105.2 g. By mounting the prototype mold on the header machine, it was possible to prevent metal flow breakage, as shown by the trial mass production test. It was possible to improve the strength of the eccentric head bolt and reduce the weight of the input material through the cutting process. Therefore, manufacturing costs could be reduced.
In this research, the small punch (SP) test was applied to examine the local creep characteristics of a narrow gap weldment. To find the local creep property, an Ni-based 617 alloy and its narrow gap weldment. which is one of candidates for advanced fossil power plants, were employed. Thin square specimens were machined at three different locations: weld metal, base metal, and HAZ near the base metal from the Inconel 617 alloy narrow gap weldment. The results of the SPC test were evaluated. The microstructure of narrow gap weldment was observed by scanning electron microscopy and optical microscopy to investigate the effect of the microstructure on the creep properties of the weld zone. The creep rupture part of the weldment was observed by scanning electron microscopy. Finally, four different creep characteristics of the narrow gap weldment were obtained by the SPC test with good validity.
In this study, the design for additive manufacturing of shoe molds with complex and precise patterns was performed to achieve rapid prototyping. Low alloy steels such as AISI4340 and SAE1524 were selected to make shoe molds to apply to the conventional chemical etching process. A lattice-oriented design and optimization of toolpath was tested to reduce the processing time. A reduction of 60% in processing time and pattern precision of 0.3 ㎜ was been achieved. Moreover, to improve the reliability of pattern formation, single-layer image analysis with computer vision and machine learning was developed and non-destructive analysis by X-ray CT was been performed. It was found that the quality of shoe molds can be decreased with a single defective layer.
Directed energy deposition (DED) additive manufacturing technology enhances the functionality of existing or damaged parts by adding metallic materials to the surfaces. Blown-powder DED technology utilizes a focused, high-energy source to fuse the part’s surface with the supplied metal powder. Maintaining a constant stand-off distance (SOD), the distance between the deposition head and the workpiece, is a key factor in ensuring deposition quality, as variations in SOD will change the powder focus position and the laser spot size on the surface. Therefore, traditional additive manufacturing systems require CAD or pre-scanned surface data. In this study, we proposed auto-surface tracking technology. No workpiece CAD data or pre-scanned surface data are required, and in-situ measurement and feedback control can automatically consider the deposition height differences that cause a change in SOD when depositing the next layer. The accuracy of the SOD measurements and feedback control error was verified using a step height sample. The mean SOD measurement error was 4.7 ㎛ with a standard deviation of 42 ㎛ (reference SOD, 14 ㎜). The feasibility of the autosurface tracking technology was confirmed through the additive manufacturing processes of the gear and an actual blanking mold applied in the defense and industrial fields.
The gear overlap ratio shows the characteristics of the spur gear and the helical gear and varies according to the torsional angle. The gear ratio, tooth width, and center distance, which are restricted in a space of performance and manufacturing and design in the gearbox, are fixed. A parametric study on modules, the number of teeth, and torsion angles was conducted to analyze the relationship between the overlap ratio and PPTE. Then, contact analysis was performed by correcting the tooth profile to improve the transmission error. Contact analysis was performed through correction of the tooth modification to improve transmission error, and the noise was analyzed according to the overlap ratio by applying a noise prediction equation.
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Study on the Modification of the Contact Pattern and Teeth Shape of Tapping Device Drive Gears Sung-Min Moon, Yong-Woo Park, Do-Young Lee, Sung-Ki Lyu Journal of the Korean Society of Manufacturing Process Engineers.2025; 24(9): 76. CrossRef
A Study on the High Efficiency and Low Noise Design of Electric Industrial Gearboxes Nam Yong Kim, Jin-Uk Baek, Sung Ki Lyu Journal of the Korean Society for Precision Engineering.2024; 41(4): 243. CrossRef
Optimal Design of Surface Pressure Strength to Prevent Gear System Pitting Phenomenon Gi-Myung Gwak, Jin-Uk Baek, Nam-Yong Kim, Sung-Ki Lyu Journal of the Korean Society of Manufacturing Process Engineers.2024; 23(1): 76. CrossRef
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With advancements in semiconductor manufacturing processes and the development of precision processing technology, flexure hinge-based ultra-precision positioning stages are widely used. In the flexure hinge, axial and bending stiffness properties greatly influence positioning performance. This study examined the stiffness properties of elliptic and parabolic 2-degrees-of-freedom (DOF) hinges, which have not been extensively discussed. The Timoshenko beam theory was applied to derive the stiffness equations for the axial and bending directions of each hinge. The stiffness properties were examined in several design conditions by comparing theoretical and finite element analyses. Based on the results of the analyses, an empirical formula in exponential form for the design of an elliptic hinge was constructed through surface-fitting. The elliptic hinge was found to be a better alternative to a circular hinge under certain design conditions by adjusting two design parameters. In the future, we will develop sophisticatedly designed hinges with improved axial and bending stiffness properties compared to the existing circular and elliptic hinges.
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Derivation and Verification of Novel Phenomenon-based Theoretical Formulas for the Axial Compliance of Circular Flexure Hinges Jun-Hee Moon, Hyun-Pyo Shin Journal of the Korean Society for Precision Engineering.2025; 42(1): 47. CrossRef
Drill processing is essential in various industries, such as automobiles and aviation. Carbide is mainly used for drilling, but cermet is also one of the most used materials. Since cermet has low reactivity with iron and low reactivity at high temperatures, excellent surface roughness can be obtained. However, experimental research comparing the performance of carbide and cermet drills is lacking. The purpose of this study was to investigate the difference in the cutting characteristics of cermet and carbide tools. The experimental conditions were feed rates of 150, 200, 250, and 300 ㎜/min and 1,000, 1,500, and 2,000 revolutions per minute. S45C was used as the workpieces. In this study, surface roughness, inner diameter, and spindle load were derived as experimental results and used as indicators to evaluate the performance of carbide and cermet drills. The results showed that the performance of the cermet drill was superior to that of the carbide drill.
A microfluidics chip is a miniature analytical system that injects a small amount of reagent into microchannels formed in the chip. It controls fluid flow to perform pretreatment, detection, reaction, mixing, separation, and analysis in parallel. In this study, polygonal microchannel structures were fabricated using a microstereolithography 3D printer based on an LCoS microdisplay projector. In the experiment, the width of the microchannel structure was changed from 50 ㎛ to 500 ㎛, and the output and width of the structure were measured. Inspection of the shape of the resulting microchannel structure showed that the tip of the structure was elliptical instead of the expected rectangular shape, and the fabrication width error increased as the channel width decreased to 200 ㎛ or less. Nevertheless, it was possible to fabricate microfluidics chip structures with widths less than 100 ㎛. The results of this study demonstrate the applicability of an LCoS microdisplay project-based 3D printer for the fabrication of microfluidic channel structures.
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Single-Layer Photopolymerization Process for the Rapid Fabrication of Nature-Inspired Multifunctional Films Sai Hamsitha Reddy Guvvala, Mohammed Gayasuddin Shaik, Ketki M. Lichade Journal of Manufacturing Science and Engineering.2025;[Epub] CrossRef
As electrification trends for the automotive industry have accelerated and the demand for high efficiency has increased, hybrid transmissions have been pushed to enlarge the operating range of EOP. And in conventional transmissions, an Idle Stop and Go (ISG) EOP is becoming imperative. The operating conditions of the ISG EOP make it difficult to gain advantages by masking the effects of engine firing or drive noise. Thus, it is necessary to study noise in operating ISG EOPs. Also, the EOP inner components require precise processing and manufacturing because they should be made to a compact size owing to vehicle layout limitations. This paper first describes the results of an experimental study on the abnormal vibration phenomenon, which makes EOP operating noise worse. And secondly it was investigated the cause of abnormal vibration phenomenon which occurs due to processing and manufacturing problems in the process of developing the operating noise of the EOP for ISG on FF type automatic transmission. Finally, the verification results after improvement were described.
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