Study on the Design of Underwater Chain Trencher

N. L. D. Hai(Nguyen Le Dang Hai),J. Kim,O S. Kwon,J. H. Ko 유공압건설기계학회 2019 유공압건설기계학회 학술대회논문집 Vol.2019 No.6

In this study, a design process for an underwater trencher is introduced. Design optimization based on genetic algorithm is applied to obtain an optimal design and then chain-sprocket selection is followed. The prototype is fabricated based on the design process and is successfully demonstrated.

4개의 Halbach 어레이를 사용한 풍력 에너지 수확기의 설계 및 실험

Hai Dang Le,Soon Duck Kwon 한국풍공학회 2021 학술대회초록집 Vol.24 No.-

The Impact of Capital Requirement on Bank Performance: Empirical Evidence from Vietnamese Commercial Banks

LE, Trung Hai,NGUYEN, Ngan Bich,NGUYEN, Duong Thuy Korea Distribution Science Association 2022 The Journal of Asian Finance, Economics and Busine Vol.9 No.6

This paper examines the effects of regulatory capital on a bank's profitability and risk. We employ annual data from Vietnamese commercial banks from 2005 to 2020 and use the dynamic GMM regression method to address the potential endogeneity issue, more suitable for panel data with relatively low time dimensions. Our panel regressions indicate that higher regulatory capital would significantly improve the bank's profitability and lower the bank risks. In particular, a one percent increase in the regulatory capital would significantly increase the bank's return on assets by 1.9%. We further explore the heterogeneous impacts of regulatory capital on the Vietnamese bank's performance across bank characteristics. We find that smaller, non-state-owned and non-listed banks would benefit from stringent regulatory capital requirements. The improvements in bank performance are mainly driven by reductions in the risk premium of the banks, resulting in lower funding costs and higher profitability. These findings are essential since Vietnam, as an emerging market, has only implemented the Basel II reform recently on a stable and fast-growing background rather than as a reaction to the global financial crisis. Thus, our empirical results support stringent regulatory capital in emerging countries to ensure a stable banking sector and boost economic growth.

Effects of electron beam treatment on cotton linter for the preparation of nanofibrillated cellulose

Le Van Hai,Yung Bum Seo 한국펄프·종이공학회 2016 펄프.종이기술 Vol.48 No.2

Nanofibrillated cellulose (NFC) was prepared from cotton linter after electron beam irradiation to investigate its effects on the manufacturing efficiency of the NFC preparation and the property changes by the treatment. Mechanical device (Super Masscolloider) was used to prepare the NFC and its passing frequency for each NFC preparation was recorded. More electron beam irradiation resulted in less passing frequency. Alpha cellulose content, molecular weight, crystallinity index, and thermal decomposition behavior of each treatment were lowered by electron beam treatment (10 and 100 kGy) and grinding process. NFC films were prepared to investigate their mechanical properties. There were little changes in tensile properties of the NFC films.

Hybrid Energy Harvesting from Wind and Structural Vibration

Hai Dang Le,Phan Canh Hoang,Kwon Soon-Duck 대한토목학회 2022 대한토목학회 학술대회 Vol.2022 No.10

Right lumbar lymph trunk injury after right laparoscopic donor nephrectomy: a case report

Le Thanh Dung,Le Nguyen Vu,Than Van Sy,Tran Ha Phuong,Ninh Viet Khai,Dao Xuan Hai,Nguyen Quang Nghia 대한이식학회 2023 Korean Journal of Transplantation Vol.37 No.2

Laparoscopic donor nephrectomy (LDN) is increasingly popular because of its advantages over open surgery. Chyle leak after donor nephrectomy is a rare but potentially lethal complication if not treated appropriately. We describe a case of a 43-year-old female patient with no remarkable history who presented a chyle leak on day 2 after right transperitoneal LDN. Since conservative treatment failed, the patient underwent magnetic resonance imaging (MRI) and intranodal lipiodol lymphangiography, which confirmed the chyle leak from the right lumbar lymph trunk into the right renal fossa. The chyle leak was percutaneously embolized twice, on postoperative day (POD) 5 and POD 10, by a mixture of N-butyl-2-cyanoacrylate and lipiodol. The drainage fluid decreased significantly after the second embolization. The subhepatic drainage tube was withdrawn on POD 14, and the patient was discharged on POD 17. MRI lymphangiography and intranodal lipiodol lymphangiography effectively identified the chyle leak point. Percutaneous embolization seems to be a safe, effective method for treating high-output chyle leaks.

Adaptive hierarchical sliding mode control using an artificial neural network for a ballbot system with uncertainties

Hai Le Xuan,Quoc-Dong Hoang,Soon Geul Lee,Dat Pham Xuan,Hoang Tran Viet,Minh Pham Van,Hung Pham Van,Hung Pham Viet,PHAM DUC TUAN,Duc Anh Nguyen 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.2

Ballbots, which have been studied for over ten years, are under-actuated mobile robots that operate using the inverted pendulum paradigm. Controlling a ballbot poses a number of challenges, including maintaining the stable upright posture from the ground in all directions and making sure it follows the desired trajectory. External factors such as a minor change in contact surface properties or fabrication errors can affect the system's stabilization and transfer capabilities. In this study, an adaptive hierarchical sliding mode control algorithm based on an artificial neural network is developed to make the ballbot robust to external factors. The use of the proposed controller ensures system stability despite uncertainties including friction, accidental centrifugal forces and gravity that occur when the ballbot follows the reference trajectory. The system stability is guaranteed on the basis of Lyapunov theory. Control efficiency and robot stability under system uncertainties are demonstrated by numerical simulation.

Optimal Control Design for Block-Ice Production Process Using Time of Use Tariff

Hai Minh Le,DavidBanjerdpongchai 제어로봇시스템학회 2009 제어로봇시스템학회 국제학술대회 논문집 Vol.2009 No.8

This paper presents an application of optimal control design to a block-ice production process using the time of use tariff. The optimal strategy is developed to minimize the electricity cost over a finite-time horizon and is subjected to constraints involving control signals and state variables. Applying the principle of optimality, the control input is calculated by dynamic programming. Various factors have been analyzed with respect to energy consumption and cost. The optimal controller is then compared to the conventional control strategy. The simulation reveals that the proposed control design has asignificant advantage over the conventional control strategy.

유기물로 개질한 나노점토-폴리(에틸렌 테레프탈레이트) 복합재료의 기계적 특성

( Hai Anh Thi Le ),박용태 ( Yong Tae Park ) 한국복합재료학회 2023 Composites research Vol.36 No.4

고분자 기반 복합재료는 가볍고 우수한 물성을 가지고 있기 때문에, 단일 소재가 갖기 어려운 물성을 충족하기 위한 방법으로서 그 수요는 급격하게 증가되고 있다. 그에 따라, 크기가 1-100 nm를 갖는 입자를 고분자 기지에 분산시켜 제작하는 고분자 나노 복합재료에 대한 연구가 많이 진행되고 있다. 그리고, 나노입자 강화 복합재의 기지 재료로 열가소성 수지를 사용한 복합재료 연구를 많이 진행하고 있다. 본 연구를 통해 세틸트리메틸 암모늄브로마이드(CTAB)으로 층간 물질을 개질한 유기 나노 점토가 포함된 폴리(에틸렌 테레프탈레이트)(PET) 기반 나노 복합체를 제조하였다. 다양한 나노 점토 중에서, 질석 (vermiculite, VMT)은 저가이며 풍부한 매장량과 고유의 물성으로 인해 고분자 재료의 기계적 및 열적 특성을 증가시키는 연구들이 수행되고 있다. 하지만, VMT의 강한 층간 결합으로 인해 고분자 기지 내에서 박리 및 분산 성능이 낮아 그 활용이 제한되었다. 본 연구에서는 나노 점토의 함유량에 따른 기계적 물성을 인장 시험으로 확인하였고, 나노 점토 입자가 PET 기재 내에 분산되는 정도를 TEM 단면 사진으로 평가하고, 그리고 질소 가스 차단 특성을 측정하였다. Because polymer-based composites are lightweight and have excellent properties, their demand is growing rapidly as a way to fulfill properties that are difficult to achieve with a single material. As a result, there has been a lot of research on polymer nanocomposites, which are made by dispersing particles with a size of 1-100 nm in a polymer matrix. In addition, many nanocomposites using thermoplastic resins as matrix materials are being studied. In this study, poly(ethylene terephthalate) (PET)-based nanocomposites containing organic nanoclays modified with cetyltrimethylammonium bromide (CTAB) as interlayer materials were prepared. Among various nanoclays, vermiculite (VMT) has been studied to increase the mechanical and thermal properties of polymeric materials due to its low cost, abundant reserves and unique properties. However, the strong interlayer bonding of VMT has limited its utilization due to its poor exfoliation and dispersion performance within polymer matrices. In this study, the mechanical properties of the VMT content were confirmed by tensile tests, the dispersion of VMT particles in the PET matrix was evaluated by TEM cross-sectional images, and the nitrogen gas barrier properties were evaluated.

Diuretic efficacy and prophylactic effects of hydroethanolic extract from Musa balbisiana fruits against urolithiasis

Hai Trieu Ly,Thi Kim Oanh Le,Nguyen Minh Khoi,Van Minh Le 경희대학교 융합한의과학연구소 2022 Oriental Pharmacy and Experimental Medicine Vol.22 No.4

The use of herbs as prophylactic and prevent recurrence of urolithiasis was counseled. Musa balbisiana fruits have long been used folk in the treatment of urinary stones. However, there is no clear scientific evidence. This study was designed to investigate the diuretic and prophylactic effects of M. balbisiana fruit extract in ethylene glycol-induced urolithiasis in rats. In this study, crude extracts were extracted by maceration, hot extraction, and decoction methods. The extracts were examined in vitro biological activities of anti-urolithiatic, anti-inflammatory, antibacterial, and antioxidant properties. For in vivo study, the experimental groups of rats were given the extract for 7-day to evaluate the diuretic potential. In prophylactic activity against urolithiasis, rats were given the extract for 28-day on ethylene glycol-induced urolithiasis in male Wistar rats. The results showed that all extracts of M. balbisiana fruits exhibited in vitro anti-urolithiatic, anti-inflammatory, antibacterial, and antioxidant activities with the hydroethanolic extract by hot extraction presented the highest activities. The hydroethanolic extract at the doses of 0.8 and 1.6 g/kg had diuretic effect after 7-day of treatment. The extract at these two doses had significantly prophylactic activity restored the parameters in urine and serum to near-normal level. The histopathological examinations revealed that calcium oxalate crystal deposits in the renal tubules and congestion and dilation of the renal tubules were significantly reverted after the extract treatment for 28-day. Taken together, the hydroethanolic extract of M. balbisiana fruits had diuretic effect and reduced the growth of urinary stones showing its effect as an antiurolithiatic support agent.