http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Van-Hoang Tran,Thanh-Huan Nguyen,Frédéric Plourde,Khanh-Duy Cong Do,Duy-Hung Chung,Cong-Truong Dinh,Gia-Diem Pham 한국유체기계학회 2023 International journal of fluid machinery and syste Vol.16 No.2
In order to increase turbine efficiency while retaining structural integrity, modern jet engines need an effective cooling system. Pin-fin arrays play a significant role in the internal cooling system of the turbine blade. In examining the efficacy of cooling techniques using pin-fins, the other papers focus on pin-fin configurations. In contrast, the current study is a step toward optimizing cooling cascade endwalls for better maneuvering and reservation of vortices, which leads to more considerable heat transfer near the endwalls. This study examines the flow field and heat transfer of roughed endwall in the pin-fin channel, including varieties with flat endwall and extruded endwall. The heat transfer of the channel and pressure drop properties of the extruded endwall case are quantitatively assessed to contrast with those of the flat endwalls scenario for an intake Reynolds number range of 7400 to 36000. The leading and trailing surfaces of the channel are divided into five streamwise regions to understand better how well the pin-fins and endwalls transmit heat. The results show that the new endwall construction significantly increases the high heat transfer zones around the pin-fins compared to the flat endwall scenario. In the meantime, the heat transfer of the channel to the pin-fins is enhanced by the modified endwall configuration. The redesigned endwall outperformed the basic case regarding the HTEI, rising by 15.9%. It is found that the friction factor of the new design is increased due to the narrowing channel. However, due to their much higher heat transfer capacity, the HTEI of extruded endwall is up to 41.5% higher than the HTEI of the channel with flat endwalls. These results demonstrate that the heat transfer properties of pin-fins can be significantly improved by optimizing endwall design.
Van Duy, Nguyen,Jung, Sungwook,Nga, Nguyen Thanh,Son, Dang Ngoc,Cho, Jaehyun,Lee, Sunhwa,Lee, Wonbaek,Yi, Junsin Elsevier 2010 Materials science and engineering B. Advanced Func Vol.175 No.2
<P><B>Abstract</B></P><P>Beside silicon nitride, silicon rich SiO<SUB><I>x</I></SUB> is a good charge storage material for the charge trap type of nonvolatile memory due to the high density of the charge traps. In this study, the charge storage ability of various amorphous SiO<SUB><I>x</I></SUB> materials has been investigated. By controlling the ratio of N<SUB>2</SUB>O/SiH<SUB>4</SUB> gases from a 1:6 to a 2:1 input gas flow rate, the deposited SiO<SUB><I>x</I></SUB> bandgap changed from 2.3 to 3.9eV. The charge storage properties of the SiO<SUB><I>x</I></SUB> system were studied on metal–insulator–semiconductor structures with an insulator stack of SiO<SUB>2</SUB>/SiO<SUB><I>x</I></SUB>/SiO<SUB><I>x</I></SUB>N<SUB><I>y</I></SUB> on an n-type silicon wafer. In this structure, the SiO<SUB>2</SUB> was used for the blocking layer and the SiO<SUB><I>x</I></SUB>N<SUB><I>y</I></SUB> was used for the tunneling layer. By analyzing the FTIR and the photoluminescence spectra, it is shown that the richest silicon material incorporates numerous non-bridging oxygen hole-center (NBOHC) defect sources and a rich silicon phase in the base material. These defects, as well as the amorphous silicon clusters that exist in the SiO<SUB><I>x</I></SUB> layer, enhanced the charge storage capacity of the device compared to the oxygen rich SiO<SUB><I>x</I></SUB> cases. The retention property was optimized by surveying the tunneling thickness of the 2.3, 2.6, 2.9, and 3.2nm SiO<SUB><I>x</I></SUB>N<SUB><I>y</I></SUB> layers.</P>
Duy Van Pham,Ngoc Thuy Nguyen,강기혁,서필원,김규태,박용기,박선영 한국화학공학회 2022 Korean Journal of Chemical Engineering Vol.39 No.5
Hydrocracking of solvent deasphalted (SDA) pitch was performed in batch and semi-batch systems, at differentreaction temperatures (380-430 oC) with varying amounts of Mo-octoate precursor (0-1,000 ppm Mo) under 70-130 bar of H2 pressure. The reusability of the catalyst was also examined. Coke formation was unavoidable in thehydrocracking of the asphaltene-rich feed. The coke induction period was prolonged when the catalyst was introduced. Increasing the Mo catalyst concentration decreased the coke yield and improved the product quality. The catalytichydrocracking of the SDA pitch under high H2 pressure suppressed coke formation, promoted desulfurization,and increased the H/C ratio of the liquid products. At least 500 ppm of Mo catalyst and H2 pressur above 110 bar wererequired for the hydrocracking of SDA pitch with controllable coke generation in the semi-batch system. Sufficienthydrogen supply and moderate catalyst concentration were essential for the slurry-phase hydrocracking of asphaltenerichfeedstocks to enhance the product quality and suppress coke formation.
Van Hoang, Nguyen,Hung, Chu Manh,Hoa, Nguyen Duc,Van Duy, Nguyen,Park, Inkyu,Van Hieu, Nguyen Elsevier Sequoia 2019 Sensors and actuators. B Chemical Vol.282 No.-
<P><B>Abstract</B></P> <P>Cost-effective fabrication of sensors and detection of ultralow concentrations of toxic gases are important concerns for environmental monitoring. In this study, the reduced graphene oxide (RGO)-loaded ZnFe<SUB>2</SUB>O<SUB>4</SUB> nanofibers (ZFO-NFs) were fabricated by facile on-chip electrospinning method and subsequent heat treatment. The multi-porous NFs with single-phase cubic spinel structure and typical spider-net morphology were directly assembled on Pt-interdigitated electrodes. The diameters of the RGO-loaded ZFO-NFs were approximately 50–100 nm with many nanograins. The responses to H<SUB>2</SUB>S gas showed a bell-shaped behaviour with respect to RGO contents and annealing temperatures. The optimal values of the RGO contents and the annealing temperatures were found to be about 1.0 wt% and 600 °C, respectively. The response of the RGO-loaded ZnFe<SUB>2</SUB>O<SUB>4</SUB> NFs to 1 ppm H<SUB>2</SUB>S gas was as high as 147 at 350°C while their cross-gas responses to SO<SUB>2</SUB> (10 ppm), NH<SUB>3</SUB> (100 ppm), H<SUB>2</SUB> (250 ppm), C<SUB>3</SUB>H<SUB>6</SUB>O (1000 ppm), and C<SUB>2</SUB>H<SUB>5</SUB>OH (1000 ppm) were rather low (1.8−5.6). The high sensor response was attributed to formation of a heterojunction between RGO and ZnFe<SUB>2</SUB>O<SUB>4</SUB> and due to the fact that NFs consisted of many nanograins which resulted in multi-porous structure and formation of potential barriers at grain boundaries.</P> <P><B>Highlights</B></P> <P> <UL> <LI> rGO-loaded ZnFe<SUB>2</SUB>O<SUB>4</SUB> nanofibers have simply prepared by electrospinning. </LI> <LI> rGO-loaded ZnFe<SUB>2</SUB>O<SUB>4</SUB> nanofiber sensors can detect H<SUB>2</SUB>S gas down to ppb level. </LI> <LI> The loading rGO can result in an enhancement of H<SUB>2</SUB>S gas ensing performance. </LI> </UL> </P>
Van Duy, Nguyen,Jung, Sungwook,Kim, Kwangryul,Son, Dang Ngoc,Nga, Nguyen Thanh,Cho, Jaehyun,Choi, Byoungdeog,Yi, Junsin Institute of Physics [etc.] 2010 Journal of physics. D, applied physics Vol.43 No.7
<P>Silicon-rich SiO<SUB><I>x</I></SUB> material is a good charge storage candidate for memory applications that promise a large memory window and low operation voltage. Nonvolatile memory (NVM) devices fabricated on excimer laser-annealed polysilicon using SiO<SUB>2</SUB>/SiO<SUB><I>x</I></SUB>/SiO<SUB><I>x</I></SUB>N<SUB><I>y</I></SUB> (OOxOn) structure are investigated with SiO<SUB>2</SUB> blocking thicknesses changing from 15 to 20 to 30 nm. The Si-rich SiO<SUB><I>x</I></SUB> material exposed numerous non-bridging oxygen hole-centre defect sources and a rich silicon phase in the base material. These defects, as well as amorphous silicon clusters existing in the SiO<SUB><I>x</I></SUB> layer, enhance the charge storage capacity of the device. Retention properties were ensured by 3.2 nm SiO<SUB><I>x</I></SUB>N<SUB><I>y</I></SUB> tunnelling layer growth via N<SUB>2</SUB>O plasma-assisted oxynitridation. NVM characteristics showed a retention exceeding 85% of the threshold voltage shift after 10<SUP>4</SUP> s and greater than 70% after 10 years. Depending on the blocking thickness of 15, 20 or 30 nm, operating voltages varied from ±9 to ±13 V at a programming/erasing duration of only 1 ms. These excellent operating properties of the OOxOn structure make it a potential competitor among the new generation of memory structures on glass.</P>
Influence of Overconfidence and Cash Flow on Investment in Vietnam
NGUYEN, Duy Van,DANG, Duong Quy,PHAM, Giang Hoang,DO, Du Kim Korea Distribution Science Association 2020 The Journal of Asian Finance, Economics and Busine Vol.7 No.2
CEOs Overconfidence can bring potentially risky early decisions to businesses, along with large enterprise free cash flow that can bring different investment decisions with CEOs Overconfidence. Especially in the context of Vietnamese enterprises, CEOs are often influenced by behavioral psychology about overconfidence in investment decisions (due to individual cultural characteristics as well as operating financial markets also depend on many factors outside the market). Therefore, the authors study the impact of overconfidence and cash flow on investment in Vietnamese to find the internal relationship between these three factors in the financial environment in Vietnam. With 480 companies listed on the Vietnam Stock Exchange from 2014 to 2018 (companies have continuous reports), the regression analysis results with panel data (FEM, GLS models, correction of robust and GMM dealing with endogenous problems) have shown Overconfidence has a positive impact on investment. At the same time, the results also indicated that enterprises with overconfident CEOs and large cash flows tend to invest less than enterprises with low cash flow. The results of this study have shown the behavioral behavior of CEOs in Vietnamese enterprises that exist under both prospect theory and effective market theory.
Tobacco Control Policies in Vietnam: Review on MPOWER Implementation Progress and Challenges
Hoang, Van Minh,Tran, Thu Ngan,Vu, Quynh Mai,Nguyen, Thi Tuyet My,Le, Hong Chung,Vu, Duy Kien,Tran, Tuan Anh,Nguyen, Bao Ngoc,Vu, Van Giap,Nguyen, Manh Cuong,Pham, Duc Manh,Kim, Bao Giang Asian Pacific Journal of Cancer Prevention 2016 Asian Pacific journal of cancer prevention Vol.17 No.no.sup1
In Vietnam, the WHO Framework Convention on Tobacco Control (WHO FCTC) took effect in March 2005 while MPOWER has been implemented since 2008. This paper describes the progress and challenges of implementation of the MPOWER package in Vietnam. We can report that, in term of monitoring, Vietnam is very active in the Global Tobacco Surveillance System, completing two rounds of the Global Adult Tobacco Survey (GATS) and three rounds of the Global Youth Tobacco Survey (GYTS). To protect people from tobacco smoke, Vietnam has issued and enforced a law requiring comprehensive smoking bans at workplaces and public places since 2013. Tobacco advertising and promotion are also prohibited with the exception of points of sale displays of tobacco products. Violations come in the form of promotion girls, corporate social responsibility activities from tobacco manufacturers and packages displayed by retail vendors. Vietnam is one of the 77 countries that require pictorial health warnings to be printed on cigarette packages to warn about the danger of tobacco and the warnings have been implemented effectively. Cigarette tax is 70% of factory price which is equal to less than 45% of retail price and much lower than the recommendation of WHO. However, Vietnam is one of the very few countries that require manufacturers and importers to make "compulsory contributions" at 1-2% of the factory price of cigarettes sold in Vietnam for the establishment of a Tobacco Control Fund (TCF). The TCF is being operated well. In 2015, 67 units of 63 provinces/cities, 22 ministries and political-social organizations and 6 hospitals received funding from TCF to implement a wide range of tobacco control activities. Cessation services have been starting with a a toll-free quit-line but need to be further strengthened. In conclusion, Vietnam has constantly put efforts into the tobacco control field with high commitment from the government, scientists and activists. Though several remarkable achievements have been gained, many challenges remain. To overcome those challenges, implementation strategies that take into account the contextual factors and social determinants of tobacco use in Vietnam are needed.