Method for Local Contrast Control in DCT Domain

Tran, Nhat Huy,Minh Trung Bui,김원하,김선국 한국방송·미디어공학회 2013 한국방송공학회 학술발표대회 논문집 Vol.2013 No.11

We implement the foveation and frequency sensitivity feature of human visual system in discrete cosine transform (DCT) domain. Resolution of human visual perception decays as distance from the eye-focused point, known as foveation property, and the middle frequency components give most pleasant image quality to human than the low and high frequency components, which is the frequency sensitivity property of human visual system. For satisfying the foveation property, we enhanced the local contrast at the focused regions and smoothed local contrast at the non-focused regions in the DCT domain without bringing the blocking and ringing artifacts. Moreover, the energies at each DCT frequency components is modified with various degree to fulfill the frequency sensitivity property. The proposed method is verified by the subjective and objective evaluations that it can the improve the human perceptual visual quality.

Impact of Service Quality and Perceived Value on Customer Satisfaction and Behavioral Intentions: Evidence from Convenience Stores in Vietnam

TRAN, Van Dat,LE, Nhat Minh Trang Korea Distribution Science Association 2020 The Journal of Asian Finance, Economics and Busine Vol.7 No.9

This research investigates the relationship among product quality, service quality, perceived value, customer satisfaction, and behavior intentions. Validated measurements were identified from a literature review. The measurement model and the conceptual model depicting hypothesized relationships were evaluated based on responses from 220 customers using confirmatory factor analysis and structural equation modeling. The testing results show that, for the direct path, product quality has a significant, positive influence on customer satisfaction, and behavioral intentions. Also, perceived value directly influences customer satisfaction and behavioral intentions and satisfaction is an antecedent of behavioral intentions. For the indirect path, service quality has a significant, positive influence on behavioral intentions through the customer satisfaction. The major finding of this study suggest that service quality easily attract more customers, especially the young consumers. About the sale personnel, communication skills, knowledge and ways of treatment to customers are crucial to retailers to gain competitive advantage over competitors. Therefore, it should have clear and consistent processes, procedures with criteria that create the best condition for organization and individual to open this kind of retailing store. Furthermore, product quality improvement is essential; all products must have clear originality; and diversifying products and services is also the way to appeal more consumers.

Single image dehazing using segmenting dark channel prior

Tran, Nhat Huy,Bui, Minh Trung,Kim, Wonha(김원하) 한국방송·미디어공학회 2014 한국방송공학회 학술발표대회 논문집 Vol.2014 No.11

Desgin of Foveated Frequency Sensitivity

Tran, Nhat Huy,Bui, Minh Trung,Kim, Wonha(김원하) 한국방송·미디어공학회 2014 한국방송공학회 학술발표대회 논문집 Vol.2014 No.11

We develop the signal processing method for implementing the human perceptual variant on frequency and space. The human visual perceptual sensitivity varies as frequency components and the human perceivable resolution diminishes as the distances further from the eye-focused point. For realizing the frequency sensitivity, we developed the signal direction adaptive multiband energy scaling method to weight the frequency components. The low-pass filtering is designed on the developed energy scaling method for diminishing perceivable resolutions as the deviated distance from the eye-focused point. The developed method not only enhances the frequency components of image signals at the eye-focused region but also smoothes non-perceivable detailed image signals at non-focused regions. The proposed method is verified by the subjective and objective evaluations that it can improve human perceptual visual quality.

Robust position and vibration control of an electrohydraulic series elastic manipulator against disturbance generated by a variable stiffness actuator

Nguyen, Minh Nhat,Tran, Duc Thien,Ahn, Kyoung Kwan Elsevier 2018 Mechatronics Vol.52 No.-

<P>This paper presents an electrohydraulic series elastic manipulator (ESEM) system containing a novel variable stiffness actuator (VSA) and a hybrid robust control. The ESEM includes a series elastic manipulator (SEM), an adjustable stiffness mechanism (ASM), and an electrohydraulic servo system (EHS). Thus, the ESEM can benefit from the advantages of the EHS, such as high-power density and a high torque-to-weight ratio. Besides, the ESEM system can use the advantages of the VSA to give the system a suitable dynamic in unknown environments as well as low energy consumption for cyclic tasks. The proposed VSA adjusts the stiffness by changing the position of the springs along the ball screw. This system can provide fast stiffness regulation in a much broader range. However, the variant characteristics of the VSA, and nonlinearities and uncertainties in the EHS, such as friction, leakages, and dependence of bulk modulus on temperature, are major challenges for the control design. The new design of a backstepping adaptive fuzzy sliding mode control (BAFSMC) is addressed in this study. It is developed via sliding mode control, backstepping technique, and an adaptive fuzzy scheme. The controller is separated into two control loops for the mechanical dynamics and the hydraulic dynamics. The SMC is embedded for each loop to reduce the system's order and to ensure that the system's state variables reach and stay on the sliding surface. The adaptive fuzzy scheme is used to replace the robust term in the control effort of the conventional SMC to get rid of the chattering phenomenon and to deal with uncertainties in the mechanical and hydraulic subsystems. The Lyapunov approach and backstepping technique are used to prove the robustness and stability of the controlled system and to derive the adaptive laws. On the other hand, a fuzzy input shaping (FIS) scheme which combines an input shaping technique (IST) and a fuzzy logic system, was proposed to minimize the residual vibration at the end effector robustly over the expected operating range of the VSA system. Numerical experiments and comparisons with some existing algorithms are presented to illustrate the theoretical results and show the efficiency of the proposed controller.</P>

Method for increasing visibility in single image dehazing

Bui, Minh-Trung,Tran Nhat Huy,김원하,김선국 한국방송·미디어공학회 2013 한국방송공학회 학술발표대회 논문집 Vol.2013 No.11

Impact of Temperature and Alkalinity on Nitrogen Removal in the Start-up Period of Partial Nitrification in a Sequence Batch Reactor

( Nguyen Van Tuyen ),( Tran Hung Thuan ),( Chu Xuan Quang ),( Nhat Minh Dang ) 한국공업화학회 2023 공업화학 Vol.34 No.5

The effect of temperature and influent alkalinity/ammonia (K/A) ratio on the start-up of the partial nitrification (PN) process for an activated sludge-based domestic wastewater treatment was studied. Two different sequence batch reactors (SBR) were operated at 26 °C and 32 °C. The relationship between temperature and the concentration of free ammonia (FA) and free acid nitrite (FNA) was investigated. A stable PN process was achieved in the 32 °C reactor when the influent ammonium concentration was lower than 150 mg-N/L. In contrast, the PN process in the 26 °C reactor had a higher nitrite accumulation rate (NAR) and ammonium removal efficiency (ARE) when the influent ammonia concentration was increased to more than 150 mg-N/L. Then three different ranges of the K/A ratio were applied to an SBR reactor. In the K/A range of 2.48~1.65, the SBR reactor achieved the highest NAR ratio (75.78%). This ratio helps to achieve the appropriate level of alkalinity to maintain a stable pH and provide a sufficient amount of inorganic carbon source for the activity of microorganisms. At the same time, FA and FNA values also reached the threshold to inhibit nitrite-oxidizing bacteria (NOB) without a significant effect on ammonia-oxidizing bacteria (AOB). Results showed that the control of temperature and K/A ratio during the start-up period may be important in establishing a stable and steady PN process for the treatment of domestic wastewater.

Factors Affecting Enterprises that Apply the International Financial Report Standards (IFRS): A Case Study in Vietnam

NGUYEN, Thi Le Hang,LE, Tran Hanh Phuong,DAO, Nhat Minh,PHAM, Ngoc Toan Korea Distribution Science Association 2020 The Journal of Asian Finance, Economics and Busine Vol.7 No.12

In the global trend toward economic integration, Vietnamese enterprises desire to attract investment and increase competitiveness in the global market, so they have been required to provide transparent, high-quality financial reports following the International Financial Reports Standards (IFRS). Based on the roadmap drawn by the Vietnam Ministry of Finance, the foreign-invested enterprises, listed enterprises and state-owned enterprises will be applying IFRS in 2030. However, some enterprises in Vietnam have applied IFRS in the presentation of financial statements at the request of related parties for a while. The main research objective of this paper focused on examining the factors affecting the implementation of IFRS in Vietnamese enterprises through descriptive statistics tools, Cronbach's Alpha testing, EFA and logistics regression analysis with the sample collected from 254 Vietnamese enterprises. The methodology in this research was the mixed qualitative and quantitative method. The results show that the higher the profitability, debt ratio and firm size of the enterprise, the more likely it is to apply IFRS. From the results of this study, the appropriate recommendations have been made to promote the implementation of IFRS by Vietnamese enterprises effectively and following the IFRS application roadmap of the Ministry of Finance of Vietnam.

Antimicrobial Activity of Phenolic-Rich Extracts from Mango Seed Kernel on Microorganisms

Tam Dang Thi Thu,Binh Ly Nguyen,Nhan Tran Chi,Loc Nguyen Bao,Phuong Nguyen Nhat Minh 한국미생물·생명공학회 2023 한국미생물·생명공학회지 Vol.51 No.4

Replacing synthetic additives to preserve food products with natural antimicrobial compounds needs to be considered due to public health. In the present study, the phenolic extract from mango seed kernel (MSK) with the total phenolic content (TPC) value of 5300 ± 380 mg gallic acid equivalent (GAE)/L was used for evaluating the antimicrobial properties against five types of bacterial strains, including Listeria monocytogenes, Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, and Salmonella typhimurium in vitro. This extract was also used for in situ method on the storage of Pangasianodon hypophthalmus fish fillets. The minimum inhibitory concentration (MIC) values for all tested strains were determined at an average concentration of 1325 mg GAE/L. Furthermore, the minimum bactericidal concentration (MBC) values of E. coli, S. aureus, and S. typhimurium were seen at 5300 mg GAE/L, while the extract did not show eliminations in the growth of the remaining strains. The bacterial inhibition speed of the extract illustrated that the concentration equal MIC value eliminated S. typhimurium growth after 24 h, the 4 times MIC value had remarkable effects on S. aureus growth after the 9 h of incubation, and 24 h of incubation for E. coli, L. monocytogenes, P. aeruginosa. Additionally, the MSK extract could inhibit the growth of P. aeruginosa on fish fillets in 4 days of storage. These results provide important evidence for the utilization of MSK as a natural source of antimicrobial agents in food products.

E-commerce Adoption in Distribution: An Empirical Study on Household Businesses in Food and Beverage Industry

NGUYEN, Xuan Truong,NGUYEN, Thai Ha,DANG, Huynh Phuong,PHAM, Thi Lan Phuong,BUI, Thi Thanh,TRAN, Nhat Minh,HUYNH, Tri An,NGUYEN, Nam Phong Korea Distribution Science Association 2022 유통과학연구 Vol.20 No.2

Purpose: This study aims to identify factors affecting the adoption of e-commerce by household businesses in Vietnam's food and beverage industry. Research design, data and methodology: The integrated TAM and TOE frameworks and ten hypotheses were developed to test the relationship between relevant factors. A cross-sectional survey was conducted to collect valid data from 992 respondents who run F&B household businesses in Vietnam. Results: The empirical research results confirm all proposed hypotheses that e-commerce adoption is affected by the perceived usefulness, the perceived ease of use, vendor support partners, social expectancy, competitive pressure, subjective norm, and household resources. Meanwhile, technical readiness, environment readiness, and organization readiness are intermediate variables that influence the implementation of e-commerce in food and beverage distribution. Conclusions: The findings suggest effective orientations to foster the food and beverage e-trading practice for household businesses in developing countries. Accordingly, to encourage private household businesses to adopt e-commerce, it is necessary to focus on improving business resources, technology readiness, environment readiness, and organization readiness through raising awareness of usefulness, benefits, perceived ease of use, and increased support of vendor partners. Future research can focus on improving the efficiency of e-commerce applications in F&B distribution for both household businesses and larger-scale enterprises.