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A Theoretical Deformation Prediction of Micro Channels in Ultra-precision Machining
Duong, Thanh-Hung,Kim, Hyun-Chul,Lee, Dong-Yoon,Lee, Seok-Woo,Park, Eon-Seok,Je, Tae-Jin 한국정밀공학회 2013 International Journal of Precision Engineering and Vol.14 No.2
In ultra-precision machining for micro channels, deformation occurs with high frequency. A high aspect ratio, high cutting speed, high feed rate, etc. all lead to deformation. Several studies on the deformation of the machined part of a workpiece have been conducted, but almost all of them have focused on experimental and finite element analyses, which take time and money. This paper presents a theoretical prediction solution for the deformation of the micro channels. To obtain maximum principle stress and deflection of micro rectangular pattern, the model used was a cantilever beam with a distributed load. Furthermore, for verifying this solution, experiments have been carried out to rectangular patterns by diamond turning. The maximum error between the predicted deformation and experimental deformation was approximately $5{\mu}M$, which means that this prediction solution works well.
Selection of machining conditions for microchannels in ultraprecision diamond turning
Duong, Thanh-Hung,Kim, Hyun-Chul,Lee, Dong-Yoon SAGE Publications 2013 PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGIN Vol.227 No.10
<P>In ultraprecision machining for microchannels, deformation occurs with high frequency because the diamond tool pushes against the channel structure during the machining process. Conservative cutting conditions decrease the cutting force and avoid deformation, but they reduce productivity. Therefore, it is important to select suitable cutting conditions in practice. This article presents a theoretical decision model for optimum machining conditions in manufacturing rectangular micropatterns. The model involves the prediction of cutting force and deformation. To forecast deformation phenomena, a rectangular pattern was considered as a cantilever beam with a distributed load, and the maximum principal stress that acts on the rectangular micropatterns could then be determined. For verifying this solution, several experiments were carried out to obtain a rectangular pattern by single-point diamond turning. Finally, the machining condition decision model was implemented and verified in practice.</P>
Duong, Thanh-Hung,Kim, Hyun-Chul American Chemical Society 2018 INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH - Vol.57 No.8
<P>Recently, flexible transparent electrodes have been fabricated successfully by using silver and copper nanowires. Silver is expensive and scarce, while copper is inexpensive but it requires a complex post-treatment process to obtain copper nanowire electrodes with an equivalent performance. In this study, by using polyvinylpyrrolidone-based ink and ultralong copper nanowires, a simple and low-cost approach has been presented for the fabrication of excellent copper nanowire-based flexible transparent electrodes. When ultrahigh aspect ratio copper nanowires and 0.5 wt % polyvinylpyrrolidone-based ink are applied to coat onto a substrate, the post-treatment process can be simplified to dipping once in acetic acid for 60 s. When compared to previously reported studies, our copper nanowire electrodes proved to be one of the best quality transparent electrodes. Moreover, these electrodes were applied successfully in the fabrication of self-capacitance button touch sensors.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/iecred/2018/iecred.2018.57.issue-8/acs.iecr.7b04709/production/images/medium/ie-2017-04709a_0010.gif'></P>
A dense, pinholes-free pure cubic phase CsPbBr3 nanocrystals film for high-performance photodetector
Thanh-Tung Duong,Phuong-Nam Tran,Tuan-Pham Van,Duy-Hung Nguyen,Van-Dang Tran 대한금속·재료학회 2024 ELECTRONIC MATERIALS LETTERS Vol.20 No.2
This study demonstrates a simple centrifugal coating method to prepare high-quality pure cubic phase CsPbBr 3 nanocrystalfi lm. The resultant perovskite layers possess a uniform and dense 500 nm-thick, with a bandgap of 2.38 eV, a low trap-statedensity of 6.9 × 10 − 15 cm − 3 , and carrier mobility of approximately 19.8 cm 2 V − 1 s − 1 . Furthermore, CsPbBr 3 NCs-basedself-powered photodetectors with high charge carriers’ charge transfer are fabricated. The device shows a low dark currentdensity of 1.93 × 10 − 7 A/cm 2 at room temperature. Such photodetectors show the highest responsivity of 3.0 AW − 1 ,specifi c detectivity of 1.2 × 10 13 Jones, and external quantum effi ciency (EQE) of 920% at zero bias voltage. The proposedmethod shows signifi cant promise for use in the lab fabrication of optoelectronic devices based on thin fi lms of nanocrystalperovskite materials.
Salvage embolization after surgery failure in hemodynamically unstable severe-grade liver trauma
Duc Hung Duong,Thanh Dung Le,Van Sy Than,Huu Khuyen Pham 소화기인터벤션의학회 2024 International journal of gastrointestinal interven Vol.13 No.3
The liver is commonly injured after blunt abdominal trauma. The choice of treatment for liver trauma depends not only on injury severity but also on the patient’s hemodynamic status. Most minor- and moderate-grade liver injuries in hemodynamically stable patients allow for conservative treatment or minimal intervention, while emergency laparotomy is indicated for patients with severe-grade liver trauma and hypotensive shock. We describe a 19-year-old male patient with traumatic shock due to grade IV liver injury and multiple fractures. An emergency laparotomy was performed, but the bleeding could not be controlled, and the patient remained hemodynamically unstable. Hyperacute transarterial embolization was successfully performed. In this case report, we emphasize the importance of transarterial embolization in cases of residual bleeding after initial damage-control surgery, even in hemodynamically unstable patients.