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A Novel Design of Suspension System for Driver's Seat
Thanh-Tung Luu(Thanh-Tung Luu),박성태(Sung-Tae Park) 한국자동차공학회 2005 한국자동차공학회 춘 추계 학술대회 논문집 Vol.2005 No.5_2
A driver's seat can be modeled with a suspension system of spring, mass and damper. To increase the capacity of anti-vibration, the natural frequency should be decreased as low as possible. In this paper, the method to decrease the natural frequency by the potential energy is introduced. In addition, the experiment is done on a small model to prove the theorem.
Thanh-Tung Duonga,Phan Huy Hoang,Luu Thi Nhan,Luong Van Duong,Man Hoai Nam,Le Quoc Tuan 한국물리학회 2019 Current Applied Physics Vol.19 No.11
Large-grain-size and void-free CH3NH3PbI3 films with bilayer structure are fabricated by spin-coating a PbI2 layer onto a mesoporous TiO2 layer and sequentially spraying CH3NH3I (methylammonium iodide, MAI) multilayers. The sprayer is controlled by a homemade three-axis computer numerical control machine; thus, the substrates are coated by successive parallel passes achieved by moving the nozzle. Spray deposition at the optimal spray rate and substrate temperature produces a large-grain-size and void-free methylammonium lead iodide (MAPbI3) bilayer structure. The mesoporous TiO2 layer plays an important role in electron transport by preventing the return of electrons to the perovskite layer and decreasing the contact resistance at the perovskite/ compact TiO2/fluorine tin oxide interface. When the films are incorporated into a solar cell device with a conductive carbon counter electrode, a maximum power conversion efficiency of 10.58% is realised.
Thanh Nguyen,Tung M. Luu,Thang Vu,Chang D. Yoo 대한전자공학회 2021 대한전자공학회 학술대회 Vol.2021 No.6
The main challenge of reinforcement learning from image-based observation is sample inefficient. Learning a good general feature representation on upstream task which then fine-tune to multiple downstream tasks is a good strategy but haven’t well explore. Using this strategy, this paper proposes a Self-supervised Pretraining Framework for Learning feature Representation (SPF) in visual observation reinforcement learning. SPR pre-train an general feature encoder on proxy task follow forward dynamic model signal using contrastive learning loss instead of relying on specific task reward. Then, this general feature encoder can be reuse on multiple downstream tasks to learn reinforcement policy. Experimental results on a diverse set of image-based continuous control tasks from Deep Mind Control Suite shows that SPF significantly improve sample efficiency compare to recent advance approaches.
Electromigration with enhanced green emission in the titanium dioxide nanotube/graphene composite
Tri Tuan Nguyen,Tran Thanh Tung,Dusan Losic,Luu Thi Lan Anh,Le Hong Phuc,Xuan Sang Nguyen 한국물리학회 2019 Current Applied Physics Vol.19 No.10
One of the most studied photoluminescence emission peaks of anatase titanium dioxide (TiO2) is green, located at about 520 nm, which is assigned to the radiative recombination between a mobile electron in the conduction band and oxygen vacancy defect as a trapped hole in the bandgap. Composite materials of TiO2 with graphene are normally shown by the gradual quenching of photoluminescence intensity as a result of carrier lifetime extension, which is important to enhance photocatalytic activity. Herein we report an observation of the intensity enhancement of the green PL emission in a composite TiO2 nanotube (TNT) and graphene produced through facile hydrothermal synthesis. The heterojunction formation of graphene and TNT makes the excited photoelectrons easy to diffuse from TNT to graphene. Hence, the recombination rate of mobile electrons in graphene and trapped holes located on the nanotube surface is enhanced due to the high mobility of electrons in graphene.
Huynh Quynh Thi Vu,Ho Ban Tran,Le Nguyen Quoc Khanh,Trinh Tung Huu,Lam Luu Ho Thanh,Nguyen Ngan Thi Kim,Huang Shih-Yi 대한소아내분비학회 2022 Apem Vol.27 No.2
Purpose: Cranial magnetic resonance imaging (MRI) is recommended to identify intracranial lesions in girls with central precocious puberty (CPP). Yet, the use of routine MRI scans in girls with CPP is still debatable, as pathological findings in girls 6 years of age or older with CPP are limited. Therefore, we aimed to identify the prevalence of brain lessons in CPP patients stratified by age group (0–2, 2–6, and 6–8 years).Methods: This retrospective cross-sectional study recruited 257 girls diagnosed with CPP for 6 years (2010–2016). MRI was used to detect brain abnormalities. Levels of luteinizing hormone, follicle-stimulating hormone, and sex hormones in blood samples were measured.Results: Most girls had no brain lesions (82.9%, n=213), and of the minor proportion of girls with CPP that exhibited brain lesions (17.1%, n=44), 32 girls had organic CPP. Pathological findings were detected in 33.3% (2 of 6) of girls aged 0–2 years, 15.6% (5 of 32) of girls aged 2–6 years, and 3.6% (8 of 219) of girls aged 6–8 years. Hypothalamic hamartoma and tumors in the pituitary stalk were the most common pathological findings. The likelihood of brain lesions decreased with age. Girls with organic CPP were more likely to be younger (6.1±2.4 vs. 7.3±1.3 years, p<0.01) than girls with idiopathic CPP.Conclusion: Older girls appeared to have a lower prevalence of organic CPP. Clinicians should cautiously use cranial MRI for girls aged 6–8 years with CPP.
Huynh Quynh Thi Vu,Ho Ban Tran,Le Nguyen Quoc Khanh,Trinh Tung Huu,Lam Luu Ho Thanh,Nguyen Ngan Thi Kim,Huang Shih-Yi 대한소아내분비학회 2022 Annals of Pediatirc Endocrinology & Metabolism Vol.27 No.2
Purpose: Cranial magnetic resonance imaging (MRI) is recommended to identify intracranial lesions in girls with central precocious puberty (CPP). Yet, the use of routine MRI scans in girls with CPP is still debatable, as pathological findings in girls 6 years of age or older with CPP are limited. Therefore, we aimed to identify the prevalence of brain lessons in CPP patients stratified by age group (0–2, 2–6, and 6–8 years). Methods: This retrospective cross-sectional study recruited 257 girls diagnosed with CPP for 6 years (2010–2016). MRI was used to detect brain abnormalities. Levels of luteinizing hormone, follicle-stimulating hormone, and sex hormones in blood samples were measured. Results: Most girls had no brain lesions (82.9%, n=213), and of the minor proportion of girls with CPP that exhibited brain lesions (17.1%, n=44), 32 girls had organic CPP. Pathological findings were detected in 33.3% (2 of 6) of girls aged 0–2 years, 15.6% (5 of 32) of girls aged 2–6 years, and 3.6% (8 of 219) of girls aged 6–8 years. Hypothalamic hamartoma and tumors in the pituitary stalk were the most common pathological findings. The likelihood of brain lesions decreased with age. Girls with organic CPP were more likely to be younger (6.1±2.4 vs. 7.3±1.3 years, P<0.01) than girls with idiopathic CPP. Conclusion: Older girls appeared to have a lower prevalence of organic CPP. Clinicians should cautiously use cranial MRI for girls aged 6–8 years with CPP.