Memristor Binarized Neural Networks

Khoa Van Pham,Tien Van Nguyen,Son Bao Tran,HyunKyung Nam,Mi Jung Lee,Byung Joon Choi,Son Ngoc Truong,Kyeong-Sik Min 대한전자공학회 2018 Journal of semiconductor technology and science Vol.18 No.5

Binarized Neural Networks (BNNs) use only binary synapses of +1 and -1, not allowing any intermediate weights between -1 and +1. Though the recognition rate of BNNs is lower than the conventional Deep Neural Networks (DNNs), BNNs have attracted many interests nowadays, because BNNs do not need the complicated multiplication such as DNNs. Binary memristor crossbars can be very suitable to realize BNN hardware. This is because, in memristor BNNs, simple binary operation can be performed in bitwise manner for all the columns in memristor crossbars, simultaneously. In this paper, single-column and double-column memristor BNNs are presented, respectively. In addition, ReLU and sigmoid activation function circuits are also proposed with CMOS circuits. The designed Memristor-CMOS hybrid circuits of BNNs have been tested for MNIST vectors. The memristor BNNs could recognize almost 90% MNIST digits when the memristance variation is as large as 25%. For variation tolerance, the memristor BNNs are compared with the multi-valued memristor neural networks such as 4-bit, 6-bit, etc, in this paper. As a result, it has been confirmed the memristor BNNs become more variation-tolerant than the multi-valued memristor NNs when the variation becomes larger than 22%. Comparing the single-column and doublecolumn BNNs in this paper indicates that the singlecolumn BNN can save power consumption and array area almost by half than the double-column. This is because the single-column has just half memristors than the double-column. And, we measured the single-column and double-column BNNs using the fabricated memristor array. In this measurement, both the double-column and single-column BNNs were observed to work well.

Efforts in the Formation and Development of Nuclear Medicine in Vietnam

Trong Khoa Mai,Cam Phuong Pham,Tien Cong Bui,Hai Binh Tran,Van Thai Pham,Manh Phuong Dao,Dinh Ha Tran 대한핵의학회 2019 핵의학 분자영상 Vol.53 No.2

The foundations of nuclear medicine in Vietnam were established from 1970. Until now, after 48 years of development, in Vietnam, we have some basic equipment including 31 SPECT, 4 SPECT/CT machines, 11 PET/CT scanners, five cyclotrons, and one nuclear reactor.Many nuclearmedicine techniques in diagnosis and treatment have been routinely performed at provincial and central level health facilities such as tumor scintigraphy, thyroid scintigraphy, bone scintigraphy, kidney scintigraphy, cardiac scintigraphy, and radio-isotope therapy with I-131 and P-32. Selective internal radiation therapy with Y-90 microsphere and I-125 radioactive seed implantation has been also successfully applied in some big hospitals. However, there are still many difficulties for Vietnam as the lack of new widely used radioisotopes such as Ga-67, Cu-64, Samarium-153, and Lutetium-177 and the lack of nuclear medicine specialists. In the future, we are putting our efforts on the applications of new isotopes in diagnosis and treatment of cancers (theranostic) like Ga-68-DOTATATE, Lutetium-177-DOTATATE, Ga-68-PSMA, and Lutetium-177-PSMA, equipping modern nuclear medicine diagnostic tools, strengthening the human resources training in nuclear medicine. At the same time, we are trying our best to strengthen the cooperation with international nuclear medicine societies in over the world.

A highly sensitive fluorescent chemosensor for simultaneous determination of Ag(I), Hg(II), and Cu(II) ions: Design, synthesis, characterization and application

Hien, Nguyen Khoa,Bao, Nguyen Chi,Ai Nhung, Nguyen Thi,Trung, Nguyen Tien,Nam, Pham Cam,Duong, Tran,Kim, Jong Seung,Quang, Duong Tuan Elsevier 2015 Dyes and pigments Vol.116 No.-

<P><B>Abstract</B></P> <P>A fluorescent chemosensor based on dimethylaminocinnamaldehyde-aminothiourea (DA) has been designed, synthesized, and applied with a combined theoretical and experimental study. The synthetic path, optimized molecular structure and characteristics of DA were carried out using the calculations at the B3LYP/LanL2DZ level of theory. The experimental investigations have a good agreement with the theoretical results. DA can be used as a chemosensor for simultaneous quantification of silver, copper, and mercury ions in aqueous solution at the ppb level. The stable geometric structures of the complexes between DA and Ag<SUP>+</SUP>, Hg<SUP>2+</SUP>, Cu<SUP>2+</SUP> with stoichiometry of 1:1, 2:1, and 2:1, have been found and investigated for electronic properties and fluorescence quenching phenomena by using Atoms in Molecules (AIM) and Natural Bond Orbitals (NBO) analyses.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A chemosensor has been studied with a combined theoretical and experimental study. </LI> <LI> Suitable for detecting trace amounts of Ag(I), Hg(II), Cu(II) ions at the ppb concentration level. </LI> <LI> High water solubility, simplicity, rapid analysis time, wide range of pH. </LI> <LI> The stable geometric structures of the complexes have been found and investigated. </LI> <LI> The fluorescence quenching of complexes is studied by using AIM and NBO analyses. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Fabrication and modification of cellulose aerogels from Vietnamese water hyacinth for oil adsorption application

La Nam Phat,Tran Quoc Thang,Huynh Cam Nguyen,Dang Thi My Duyen,Dao Xuan Tien,Bui Dang Dang Khoa,Pham Tan Khang,Nguyen Thi Huong Giang,Hoang Minh Nam,Mai Thanh Phong,Nguyen Huu Hieu 한국화학공학회 2021 Korean Journal of Chemical Engineering Vol.38 No.11

Recycling biomass to cellulose aerogel (Cell-A) provides a promising approach to develop adsorbent materials for spilled-oil recovery. In this work, Cell-A was fabricated from Vietnamese water hyacinth via crosslinking methods using PVA as a crosslinker and freeze-drying process. Various cellulose to PVA ratios were investigated to obtain the optimal synthesis condition. The Cell-A was additionally modified by dip-coating in poly(dimethylsiloxane) (PDMS) and pyrolyzing to form PDMS-coated cellulose aerogels (Cell-AP) and carbon aerogels (CA), respectively. Results of the oil adsorption tests show that pyrolysis produced aerogels with greater adsorption capacity with an optimal mass ratio of 15 : 1 cellulose to PVA. Furthermore, the pseudo-second-order model was found to be more accurate than the pseudo-first-order model for the study of oil absorption kinetics. As a result, the modified cellulose aerogel is promising for replacing earth-unfriendly polymer-based oil sorbents due to their high oil absorption capacity.

Solution-Processed Transparent Intermediate Layer for Organic Tandem Solar Cell Using Nitrogen-Doped Graphene Quantum Dots

Ho, Nhu Thuy,Van Tam, Tran,Tien, Huynh Ngoc,Jang, Se-Jeong,Nguyen, Tri Khoa,Choi, Won Mook,Cho, Shinuk,Kim, Yong Soo American Scientific Publishers 2017 Journal of Nanoscience and Nanotechnology Vol.17 No.8

<P>The solution-processed intermediate layer (IML), which physically and electrically connects two subcells, is critical in the fabrication of efficient organic tandem solar cells. Several studies have examined solution-processed electron transport materials that can be used as n-type layers in the IML. On the other hand, forming an Ohmic contact for holes is limited by the choice of an aqueous-based hole transport layer (HTL) material except for PEDOT:PSS or vacuum evaporating materials. Here, this paper reports highly transparent and solution-processable nitrogen-doped graphene quantum dots (N-GQDs) as an efficient HTL in the IML. Using an IML based on N-GQDs/PEI, the present P3HT:PCBM tandem device showed a slight improvement in the fill factor (10%) and efficiency (15%) compared to the devices using the PEDOT: PSS/PEI-based junction. The optimal tandem cells with N-GQDs showed a double open-circuit voltage of 1.16 V, short-circuit current density of 5.80 mA/cm(2), fill factor of 0.55, and power conversion efficiency of 3.69% under AM 1.5G solar irradiation. This result thus makes a start on the use of functional graphene quantum dots in organic tandem solar cells.</P>

Thermal Energy Harvesting용 센서회로의 저전력 구동 방법

남현경,코아반팜,트란바오손,응웬반티엔,민경식,Nam, Hyun Kyung,Pham, Van Khoa,Tran, Bao Son,Nguyen, Van Tien,Min, Kyeong-Sik 한국전기전자학회 2018 전기전자학회논문지 Vol.22 No.3

본 논문에서는 열전에너지 하베스팅에 의해 구동되는 센서 회로를 저전력으로 동작시킬 수 있는 방법을 제안하였다. 본 논문에서 사용되는 열전소자를 이용하면 에너지 하베스팅 회로에서 8uA의 전류를 얻을 수 있다. 그러나 구동하려고 하는 센서의 전류 소비는 이보다 훨씬 크기 때문에, 본 논문에서는 하드웨어 방법으로 power gating scheme을 이용한 저전력 구동과 소프트웨어적으로 active/sleep control scheme을 이용한 저전력 구동 방법을 센서 회로에 적용하여 센서 회로의 전류 소비를 감소시킬 수 있음을 보였다. 먼저 하드웨어 power gating scheme을 사용할 때에는 파워 게이트의 Toff/Ton의 비를 22보다 더 크게 하면, 센서 회로의 전류 소비가 8uA 이하로 줄어드는 것을 확인하였다. 또한 소프트웨어 기반의 active/sleep control scheme에 의한 저전력 구동에서는 Tslp/Tact의 비를 3 이상으로 설정해주면 전류 소비를 8uA 이하로 줄일 수 있음을 확인하였다. 본 논문에서의 결과는 열전에너지 하베스팅에 의해서 구동되는 다양한 센서 회로 설계 및 구현에 도움이 될 것으로 생각된다. In this paper, we propose low-power operational methods for thermal-energy-harvesting sensor circuits. Here, the amount of harvested current has been measured as low as 8uA. However the DC power consumption of the sensor circuit is known to consume much larger than 8uA. Thus, We propose the hardware-based power gating and software-based active/sleep timing control schemes, respectively, for controlling the power consumption of sensor circuit. In the hardware-based power gating scheme, if the ratio of Toff/Ton is larger than 22, the sensor can consume less than 8uA. For the software-based active/sleep control scheme, if the ratio of Tslp/Tact is larger than 3, we can suppress the current consumption below 8uA. The hardware-based and software-based schemes proposed in this paper would be helpful in various applications of energy-harvesting sensor circuits, where the power consumption is limited by an amount of harvested energy.

Intra-Organizational Factors Affecting Business Performance: An Empirical Study in Vietnam

Khuong Ngoc MAI,Thao Thi Thanh NGUYEN,Phuong Ngoc Duy NGUYEN,Khoa Tien TRAN 한국유통과학회 2021 The Journal of Asian Finance, Economics and Busine Vol.8 No.10

In the era of industry 4.0 with the robust digital transformation, especially under the trigger of the Covid-19 pandemic, the process of transforming businesses to achieve the desired business performance depends much on the mindset transformation of each member of the organization, beginning with the thoughts of leadership and stakeholders. This study will evaluate the relationship between leadership’s strategic reasoning perspectives on employee engagement or commitment and the company’s reputation, thereby directly or indirectly affecting organizational performance. The study examines data from 382 companies out of 500 samples in typical industries in Vietnam using the exploratory factor analysis (EFA) and partial least squares structural equation modeling (PLS-SEM) techniques. The results show that holistic thinking is closely related to employee retention and corporate reputation, thereby increasing the business outcomes of the organization, whereas there was no evidence to support analytical thinking in this study. As a consequence, transforming the business to achieve the desired business performance is heavily reliant on changing the mindset of each member of the organization, beginning with the top leaders and influencers of the business. This will assist Vietnamese leaders in gaining a comprehensive understanding of corporate governance and controlling the relationships between organizational constructs.

Copper Tolerance of Novel Rhodotorula sp. Yeast Isolated from Gold Mining Ore in Gia Lai, Vietnam

Kim Cuc Thi Nguyen,Phuc Hung Truong,Cuong Tu Ho,Cong Tuan Le,Khoa Dang Tran,Tien Long Nguyen,Manh Tuan Nguyen,Phu Van Nguyen 한국균학회 2023 Mycobiology Vol.51 No.6

In this study, twenty-five yeast strains were isolated from soil samples collected in the goldmining ore in Gia Lai, Vietnam. Among them, one isolate named GL1T could highly tolerateCu2þ up to 10 mM, and the isolates could also grow in a wide range of pH (3–7), and temperature(10–40 �C). Dried biomass of GL1 was able to remove Cu2þ effectively up to 90.49%with a maximal biosorption capacity of 18.1 mg/g at pH 6, temperature 30 �C, and incubationtime 60 min. Sequence analysis of rDNA indicated this strain was closely related toRhodotorula mucilaginosa but with 1.53 and 3.46% nucleotide differences in the D1/D2domain of the 28S rRNA gene and the ITS1-5.8S rRNA gene-ITS2 region sequence, respectively. Based on phylogenetic tree analysis and the biochemical characteristics, the strainappears to be a novel Rhodotorula species, and the name Rhodotorula aurum sp. nov. is proposed. This study provides us with more information about heavy metal-tolerant yeasts andit may produce a new tool for environmental control and metal recovery operations.