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Loi Van Le,Quang Van Vu,Thanh Van Le,Hieu Trung Le,Khue Kim Dang,Tuan Ngoc Vu,Anh Hoang Ngoc Nguyen,Thang Manh Tran 한국간담췌외과학회 2024 Annals of hepato-biliary-pancreatic surgery Vol.28 No.1
Backgrounds/Aims: Hepatolithiasis and choledocholithiasis are frequent pathologies and unfortunately, with the current treatment strategies, the recurrence incidence is still high. This study aimed to assess the outcomes of laparoscopic choledochotomy using cholangioscopy via the percutaneous-choledochal tube for the treatment of hepatolithiasis and choledocholithiasis in Vietnamese patients. Methods: A cross-sectional study of patients with hepatolithiasis and/or choledocholithiasis who underwent laparoscopic choledochotomy using intraoperative cholangioscopy via percutaneous-choledochal tube at the Department of Hepatopancreatobiliary Surgery, 108 Military Central Hospital, from June 2017 to March 2020. Results: A total of 84 patients were analyzed. Most patients were females (56.0%) with a median age of 55.56 years. Among them, 41.8% of patients had previous abdominal operations, with 33.4% having choledochotomy. All patients underwent successful laparoscopic common bile duct exploration followed by T-tube drainage without needing to convert to open surgery. Most patients (64.3%) had both intrahepatic and extrahepatic stones. The rate of stones ≥ 10 mm in diameter was 64.3%. Biliary strictures were observed in 19.1% of patients during cholangioscopy. Complete removal of stones was achieved in 54.8% of patients. Intraoperative complications were encountered in two patients, but there was no need to change the strategy. The mean operating time was 121.85 ± 30.47 minutes. The early postoperative complication rate was 9.6%, and all patients were managed conservatively. The residual stones were removed through the T-tube tract by subsequent choledochoscopy in 34/38 patients, so the total success rate was 95.2%. Conclusions: Laparoscopic choledochotomy combined with cholangioscopy through the percutaneous-choledochal tube is a safe and effective strategy for hepatolithiasis and/or choledocholithiasis, even in patients with a previous choledochotomy.
Van Loi Tran,Byeong-Cheon Kim,Thanh Thuong Do,Shengwei Zhang,Kyoungsik Chang,Sung-Tae Hong,Ulanbek Auyeskhan,Jihwan Choi,Dong-Hyun Kim 한국정밀공학회 2022 International Journal of Precision Engineering and Vol.23 No.12
The design principle of an additively manufactured (AMed) lattice structural conformal cooling channel for hot stamping is investigated. AM with selective laser melting is adopted to fabricate a lab-scale rapid cooling die filled with conformal lattice structures, which provide structural stiffness, act as thermal fins, and expedite the occurrence of turbulent flow in the channel. Three different surface area densities with the same relative volume density were considered to evaluate the heat transfer and cooling performance. Computational fluid dynamics is used to analyze the flow of coolant in the lattice structures with different surface area densities. The experimental and computational results show that if the surface density of the lattice structure is selected properly, the cooling performance can be enhanced significantly while maintaining a constant relative volume density, which directly affects the weight reduction and stiffness of the cooling die.
Electrically assisted stress relief annealing of automotive springs
박기동,Van Loi Tran,홍성태,정용하,여태식,남민재,김문조,진성우,한흥남 대한기계학회 2017 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.31 No.8
In the present study, Electrically assisted (EA) stress relief annealing for automotive springs is experimentally investigated. A concept of EA stress relief annealing is to reduce the process time by superimposing the effect of electroplasticity on that of the elevated temperature. In EA stress relief annealing, the temperature of a cold-coiled spring specimen is rapidly increased to the annealing temperature and held constant by a pulsed electric current. The experimental results show that the performance of EA stress relief annealing clearly surpasses that of a conventional stress relief process, even with a significantly shorter process time and a significantly smaller amount of energy. The result of X-ray diffraction analysis confirms that the annihilation of dislocations during EA stress relief annealing is enhanced, which strongly suggests the occurrence of the electric current induced annealing.
Do Ngoc Khue,Tran Dai Lam,Nguyen Van Chat,Vu Quang Bach,Do Binh Minh,Vu Duc Loi,Nguyen Van Anh 한국공업화학회 2014 Journal of Industrial and Engineering Chemistry Vol.20 No.4
Here we report the study on the utilization of several advanced oxidation processes such as electro-oxidation and Fenton process in simultaneous treatment of two nitramine explosives: 2,4,6-trinitrophenyl-N-metylnitramine (Tetryl) and hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX). The preliminary tests indicated that the electrolytic method using a TiO2/IrO2/RuO2-coated electrode could rapidly degrade Tetryl but not RDX. While the addition of certain amount of H2O2 induced an increase of Tetryl degradation yield but had insignificant effect on RDX decomposition, the use of Fenton’s reagent showed an enhanced efficiency in degradation of both nitramines. It can be concluded that among tested processes, Fenton process is the most effective for treatment of nitramine-containing wastewaters.
Design Approach for Additive Manufacturing of a Dynamically Functioning System: Lifeboat Hook
Ulanbek Auyeskhan,Namhun Kim,Chung-Soo Kim,Tran Van Loi,Jihwan Choi,Dong-Hyun Kim 한국정밀공학회 2022 International Journal of Precision Engineering and Vol.9 No.5
The design freedom provided by Additive Manufacturing (AM) enables the part consolidation (PC) of sophisticated mechanical assemblies. However, PC has been mainly performed for static components in assemblies with nonmoving parts. In this regard, a new approach to assembly-level Design for Additive Manufacturing (A-DfAM) considering an industrial lifeboat hook assembly with a functionally dynamic system is proposed. The methodology comprises steps starting from inputting the Computer-Aided Design (CAD) fi les for the 3D printing of the final assembly and evaluation. Throughout the design stages, opportunistic and restrictive natures of DfAM within our methodology direct engineers and designers to manufacture optimized products. In addition, a comparative assessment of the original and fi nal assemblies is also illustrated. Consequently, a significant part-count reduction after PC was achieved, and the prototype of the lifeboat hook components was printed via laser-powder bed fusion (L-PBF). This shows that by incorporating the suggested A-DfAM framework, it can serve as a potential guide to whoever intends to manufacture dynamic assemblies.