Exit CTA Conscious Warp Scheduling

Viet Tan Vo,Xuan Thien Cao,Jinsul Kim 한국디지털콘텐츠학회 2021 The Journal of Contents Computing Vol.3 No.1

Modern GPU architecture achieves a significant performance improvement over several previous GPU generations. Unfortunately, hardware resources upgrade is still underutilized. This paper targets this problem by reducing the warp waiting time when they approach the exit point at the end of CTA. Our proposed exit CTA conscious warp scheduler prioritizes warps in CTA (Cooperative Thread Arrays) which has the largest number of warps waiting at the exit point. The experiments prove that our implementation can improve the performance by 8.4% on average over the performance of baseline warp scheduler.

KAWS: Coordinate Kernel-Aware Warp Scheduling and Warp Sharing Mechanism for Advanced GPUs

Viet Tan Vo,김철홍 한국정보처리학회 2021 Journal of information processing systems Vol.17 No.6

Modern graphics processor unit (GPU) architectures offer significant hardware resource enhancements for parallel computing. However, without software optimization, GPUs continuously exhibit hardware resource underutilization. In this paper, we indicate the need to alter different warp scheduler schemes during different kernel execution periods to improve resource utilization. Existing warp schedulers cannot be aware of the kernelprogress to provide an effective scheduling policy. In addition, we identified the potential for improving resource utilization for multiple-warp-scheduler GPUs by sharing stalling warps with selected warp schedulers. To address the efficiency issue of the present GPU, we coordinated the kernel-aware warp scheduler and warp sharing mechanism (KAWS). The proposed warp scheduler acknowledges the execution progress of the running kernel to adapt to a more effective scheduling policy when the kernel progress attains a point of resource underutilization. Meanwhile, the warp-sharing mechanism distributes stalling warps to different warpschedulers wherein the execution pipeline unit is ready. Our design achieves performance that is on an average higher than that of the traditional warp scheduler by 7.97% and employs marginal additional hardware overhead.

Coordinated thread block scheduling and warp scheduler for workload distribution

Vo Viet Tan,Jihoon Lee,Pyungkoo Park 한국디지털콘텐츠학회 2020 The Journal of Contents Computing Vol.2 No.2

Throughput-oriented applications require special systems such as graphics processing units (GPUs) to achieve high efficiency. Complex applications are normally divided into smaller species of workload to be executed by utilizing parallelism. However, the workload cannot be distributed equally to every GPU resources, leading to resource underutilization. This paper proposes a simple approach to balance the workload distribution by limiting new issued Cooperative Threads Array (CTAs) to streaming processors (SMs) if they receive enough CTA. Our proposal can increase the resource utilization by prioritizing the warps belong to the last issued CTA. Experimental results show performance improvement by 1.26% on average compared to the baseline GTO (Greedy Then Oldest) warp scheduler.

Biodiesel Production From Fat of Tra Catfish and Basa Catfish (Viet Nam) Using Alkaline Catalysts

Huong, Le Thi Thanh,Tan, Phan Minh,Hoa, Tran Thi Viet,Lee, Soo The Korean Society of Applied Science and Technolo 2008 한국응용과학기술학회지 Vol.25 No.3

The fat of Tra and Basa catfish (Mekong Delta, Viet Nam) was evaluated for the first time as the potential feedstock for biodiesel production, due to its abundance, availability and cheap cost. The unsaturated fatty acid contents of Tra and Basa fat were 57.97% and 64.17%, respectively. Biodiesel was prepared from Tra and Basa fat by methanolysis reaction using alkali catalysts like sodium hydroxide and potassium hydroxide. Effects of various process parameters on biodiesel production, such as molar ratio of methanol to fat, catalyst concentration, temperature and time were investigated. As those results, the transesterification can be performed under moderate conditions, and the biodiesel yields were shown more than 90%. KOH catalyst was the best catalyst for biodiesel production from both Basa and Tra fat. As the feedstock aspect, Basa fat was indicated more efficiency than that of Tra fat. The maximum yield could be achieved by the transesterification from Basa fat with 5:1 molar ratio of methanol to fat, 0.8% KOH catalyst, $50^{\circ}C$, and 50 min. For Tra fat, the optimal condition were at 6:1 molar ratio of methanol to fat, 0.8% KOH catalyst, $50^{\circ}C$, and 45 min. Nowadays, due to cheaper cost and abundance, Tra fat is a promised resource for cheap biodiesel production in Viet Nam.

Determinants of Technical Efficiency of Microenterprises in Vietnam

Nghiem Tan LE,Hau Long LE,Truc Viet Thanh TRAN 한국유통과학회 2021 The Journal of Asian Finance, Economics and Busine Vol.8 No.6

The aim of this study is to examine the determinants of technical efficiency (TE) of microenterprises (MEs) operating in the coconut handicraft industry in the Mekong Delta of Vietnam. In the first stage of analysis, output-oriented Data Envelopment Analysis (DEA) method is employed to estimate the technical efficiency of the 120 microenterprises operating in the coconut handicraft industry in the Mekong Delta, specifically in Ben Tre province over the year 2019 by using pre-determined three input and one output variables. The estimation results reveal that on average, variable returns to scale technical efficiency (VRS TE), constant returns to scale technical efficiency (CRS TE) and scale efficiency (SE) are 68.4%, 58.0%, and 87.3%, respectively. Tobit regression is applied in the second stage to examine the influences of the determinant factors on VRS TE. The empirical findings of the study imply that firm size, membership in economic association, application of science and technology, and cost-to-revenue ratio positively affect the technical efficiency of the microenterprises operating in the coconut handicraft industry in the Mekong Delta of Vietnam. Considering the results, several governance recommendations are given for business owners to improve firm technical efficiency in order to enhance the brand name of coconut handicrafts.

An Improved LEACH Routing Protocol for Energy-Efficiency of Wireless Sensor Networks

Nguyen Duy Tan,Longzhe Han,Nguyen Dinh Viet,Minho Jo 한국산학기술학회 2012 SmartCR Vol.2 No.5

A wireless sensor network (WSN) is a wireless network consisting of a base station (BS) and multiple micro-sensor nodes. The micro-sensor nodes run on batteries that are not recharged during the network’s lifetime. Therefore, prolonging WSN lifetime is a significant problem. There are some energy-efficient hierarchical routing protocols designed especially for WSNs, such as sensor protocols for information negotiation (SPIN), low-energy adaptive clustering hierarchy (LEACH) and LEACH-centralized (LEACH-C). In this article, we propose an improvement on the LEACH routing protocol to decrease energy consumption and prolong network lifetime. LEACHDistance Energy (LEACH-DE) selects a cluster head node not only by considering residual energy of the node greater than the average residual energy level of nodes in network, but also by examining the geometric distance between the candidate node to the BS as a key parameter. The results of simulation show our proposed algorithm outperforms LEACH and LEACH-C in terms of conserving energy and prolonging WSN lifetime.

Structural Analysis of the Streptomyces avermitilis CYP107W1-Oligomycin A Complex and Role of the Tryptophan 178 Residue

Songhee HAN,Tan-Viet Pham,Joo-Hwan Kim,임영란,Hyoung-Goo Park,Gun-Su Cha,Chul-Ho Yun,Young-Jin Chun,강린우,김동학 한국분자세포생물학회 2016 Molecules and cells Vol.39 No.3

CYP107W1 from Streptomyces avermitilis is a cytochrome P450 enzyme involved in the biosynthesis of macrolide oligomycin A. A previous study reported that CYP107W1 regioselectively hydroxylated C12 of oligomycin C to produce oligomycin A, and the crystal structure of ligand free CYP107W1 was determined. Here, we analyzed the structural properties of the CYP107W1-oligomycin A complex and characterized the functional role of the Trp178 residue in CYP107W1. The crystal structure of the CYP107W1 complex with oligomycin A was determined at a resolution of 2.6 Å. Oligomycin A is bound in the substrate access channel on the upper side of the prosthetic heme mainly by hydrophobic interactions. In particular, the Trp178 residue in the active site intercalates into the large macrolide ring, thereby guiding the substrate into the correct binding orientation for a productive P450 reaction. A Trp178 to Gly mutation resulted in the distortion of binding titration spectra with oligomycin A, whereas binding spectra with azoles were not affected. The Gly178 mutant’s catalytic turnover number for the 12-hydroxylation reaction of oligomycin C was highly reduced. These results indicate that Trp178, located in the open pocket of the active site, may be a critical residue for the productive binding conformation of large macrolide substrates.

Buckling resistance of axially loaded square concrete-filled double steel tubular columns

Junchang Ci,Mizan Ahmed,Viet-Linh Tran,Hong Jia,Shicai Chen,Tan N. Nguyen 국제구조공학회 2022 Steel and Composite Structures, An International J Vol.43 No.6

Thin-walled square concrete-filled double steel tubular (CFDST) columns composed of the inner circular tube filled with concrete can be used to carry the large axial loads or strengthen existing CFST columns in composite constructions. This paper reports an experimental program carried out on short square CFDST columns loaded concentrically. The influences of important column parameters on the post-buckling performance of such columns are investigated. Test results exhibit that the inner circular tube significantly improves the ultimate loads and the ductility of such columns compared to conventional concrete-filled steel tubular (CFST) and double-skin CFST (DCFST) columns with an inner void. A mathematical model developed is used to simulate the ultimate strengths and load-strain curves of such columns loaded axially. Furthermore, the ultimate strengths of such columns are predicted using existing codified design models for conventional CFST columns as well as the formulas proposed by previous researchers and compared against a large database comprising 500 CFDST columns. Lastly, an accurate artificial neural network model is developed for the practical applications of such columns under axial loading.

Kinetics of the KOH Catalyzed-Methanolysis for Biodiesel Production from Fat of Tra Catfish

Huong, Le Thi Thanh,Tan, Phan Minh,Hoa, Tran Thi Viet,Lee, Soo The Korean Society of Applied Science and Technolo 2008 한국응용과학기술학회지 Vol.25 No.4

Transesterification of fat of Tra catfish with methanol in the presence of the KOH catalyst yields fatty acid methyl esters (FAME) and glycerol (GL). The effects of the reaction temperature and reaction time on rate constants and kinetic order were investigated. Three regions were observed. In the initial stage, the immiscibility of the Tra fat and methanol limited the reaction rate, hence this region was controlled by the mass transfer. Subsequent to this region, produced FAME like a co-solvent made the reaction mixture homogeneous, therefore the conversion rate increased rapidly so it was controlled by the kinetic parameters of the reaction until the equilibrium was approached in the final slow region. A second-order kinetic mechanism was proposed involving second regions for the forward reaction. The rate determining step for the overall KOH catalyzed-methanolysis of Tra fat was the conversion of triglycerides (TG) to diglycerides (DG). This rate constant was increased from 0.003 to $0.019min^{-1}$ when the reaction temperature was increased from 35 to $60^{\circ}C$. Its calculated activation energy was 14.379 ($kcal.mol^{-1}$).

Biodiesel Refining and Glycerin Recovering Process of Transesterification from Tra Catfish Fat

Huong, Le Thi Thanh,Tan, Phan Minh,Hoa, Tran Thi Viet,Lee, Soo The Korean Society of Applied Science and Technolo 2009 한국응용과학기술학회지 Vol.26 No.1

Nowadays, Tra catfish fat is given attention as an appropriate material for biodiesel production in Vietnam. The aim of this work is to investigate the optimal conditions of refining biodiesel and recovering glycerin by the transesterification from Tra catfish fat using KOH catalyst. As our results, the yield of transesterification was achieved to 94.17% at $50^{\circ}C$ for 45 min with 6:1 molar ratio of methanol to fat in the presence of 0.8% KOH catalyst, and wherein the biodiesel was refined by washing with distilled water at $70^{\circ}C$ and dried in a microwave oven. The yield of raw glycerin recoveries from the transesterification process was 78.58%. The purity of raw glycerin was 84.14% by the conditions of neutralization state with $H_{3}PO_{4}$ solution (pH = 5), $70^{\circ}C$, and 60 min. Activated carbon (3.0 wt.%) was used for the bleaching process at $80^{\circ}C$ for 20 min. The biodiesel was obtained in accordance with for ASTM D 6751 (biodiesel standard). The ash and water of raw glycerins were 7.32 and 8.01%, respectively, and implied that the raw glycerin is very promising candidate to be used as a raw material for textile and cosmetic industries.