Power-saving mechanism with delay bound for Mobile WiMAX systems

Nga, D. T. T.,Lim, H. IET 2011 IET COMMUNICATIONS Vol.5 No.13

<P>In Mobile World Interoperability for Microwave Access (WiMAX), the power-saving mechanism (PSM), which operates alternately in sleep and awake modes, works to extend the lifetime of mobile stations (MSs), although it concurrently induces a medium access control (MAC) service data unit (SDU) response delay. In this study, the authors derive the analytical models for two of the most important performance metrics: the average power consumption and the average MAC SDU response delay of an MS in sleep mode. These metrics are given as a function of the sleep mode system parameters: initial sleep window <I>T</I><SUB>min</SUB> and final sleep window <I>T</I><SUB>max</SUB>. Based on these models, the authors show that a tradeoff relationship exists between them. The authors then propose an optimised power-saving mechanism (OPSM) that jointly determines the optimal <I>T</I><SUB>min</SUB> and <I>T</I><SUB>max</SUB> to minimise the power consumption under a given MAC SDU response delay constraint. Through both numerical analyses and subsequent simulations, the authors show that the OPSM effectively minimises the power consumption of an MS in its sleep mode while guaranteeing the MAC SDU response delay constraint.</P>

Seed Layer Impact on Magnetic Properties of Ultra-thin IrMn₃ Films

Nga T. Do,Trang Huyen Cao Pham,Sehwan Song,Sungkyun Park,Chanyong Hwang,Tae Hee Kim 한국자기학회 2022 한국자기학회 학술연구발표회 논문개요집 Vol.32 No.2

The fig wax scale Ceroplastes rusci (Linnaeus) (Homoptera: Coccidae) in south-east Vietnam: Pest status, life history and biocontrol trials with Eublemma amabilis Moore (Lepidoptera: Noctuidae)

Nga Thi VU,Rod EASTWOOD,Chat Thi NGUYEN,Lam Van PHAM 한국곤충학회 2006 Entomological Research Vol.36 No.4

The fig wax scale Ceroplastes rusci (Linnaeus) is a serious pest of fruit trees in many countries. In the present study we investigated the extent of C. rusci infestation and the range of host species, particularly in fruit orchards, in south-east Vietnam. Captive populations of C. rusci were established to record life history parameters and to investigate the efficacy of an endemic predacious moth, Eublemma amabilis Moore, as a potential biocontrol agent. Heavy infestation of C. rusci (up to 100%) was recorded in soursop and other fruit orchards, and the culturally important Hoa Mai flower was also affected. Captive breeding trials found E. amabilis to be an efficient predator of C. rusci, but an unusual hyperactive trait in early instars of E. amabilis resulted in lower than expected survival rates.The implications of this trait in terms of the laboratory environment, augmentative release protocols and as a survival strategy are discussed.

The Impact of Exchange Rate on Exports and Imports: Empirical Evidence from Vietnam

Nga Hong NGUYEN,Hat Dang NGUYEN,Loan Thi Kim VO,Cuong Quoc Khanh TRAN 한국유통과학회 2021 The Journal of Asian Finance, Economics and Busine Vol.8 No.5

The exchange rate is considered a tool improving the volume of exports and reducing imports. This paper aims to determine the impact of the exchange rate on exports and imports between Vietnam and the United States in the context of the trade war. The research uses Autoregressive Distributed Lag (ARDL) and Nonlinear Autoregressive Distributed Lag (NARDL) Model in the time-series data from 2010:1 to 2020:9. The ARDL’s results support that real exchange rate impact on export and import volumes, but less than the trade war. The trade war helps trade balance increase 0.35%, while the exchange rate increases trade balance 0.191% when the Vietnamese currency devalues 1% in the long run. In the short term, the real exchange rate makes the trade balance decrease. Therefore, the J curve exists between Vietnam and the U.S. The NARDL expresses that the exchange rate is asymmetric both in the short term and the long term. The findings of this study point to two important elements. Firstly, the exchange rate plays a minor role in exports and imports. Secondly, trade war plays a vital role in increasing exports and imports volume between two countries, and the J curve exists between the two countries.

Cultural Factors Affecting Tendency of Ethical Decision-Making by Accounting Students: An Empirical Study in Vietnam

Nga Thanh DOAN,Trang Thu TA,Ha Thi Thanh CHU,Anh Thi Quynh LE,May Thi LE,Tuan Hoang PHAM,Thao Thu VUONG 한국유통과학회 2022 The Journal of Asian Finance, Economics and Busine Vol.9 No.2

The purpose of this study is to look at the precise direction and magnitude of cultural elements such as education, gender, power distance, and risk-taking proclivity on ethical decision-making. Data was collected from 194 interviewees in three groups: general business students, accounting major students, and professional auditors in Vietnam. The path analysis is used to test the impact of cultural factors on ethical awareness, ethical judgment, and ethical intention in different dubious scenarios at the personal level as independent variables, intermediate variables, and moderating variables. The metric is the percentage of respondents who believe a particular behavior is unethical based on a set of ethical principles. The researchers used SPSS AMOS software to conduct a confirmatory factor survey to evaluate the convergent and discriminant validity of latent variables. The results show differences between the two groups of students and professionals on these measures, suggesting that all of the four factors have an effect on ethical decision-making. Based on research results, some recommendations are proposed related to the four factors to improve the ethics of future generations of auditors in Vietnam. This study also contributes to the theory of culture in particular and cultural interference in general in the field of accounting-auditing in Vietnam in the process of international integration.

Nonlinear Speed Control of PM Synchronous Motor with Extended Kalman Filter Observer

Nga Thi-Thuy Vu,Jin-Woo Jung 한국조명·전기설비학회 2011 조명·전기설비학회논문지 Vol.25 No.3

This paper proposes a nonlinear speed controller for a permanent magnet synchronous motor (PMSM). In this paper, the load torque is estimated by an extended Kalman filter (EKF) observer because the proposed controller needs its knowledge. To confirm the effectiveness of the proposed control scheme, simulations and experiments are performed under motor parameter variations with a prototype PMSM drive system.

The Effect of Brand Equity Components on Automobile Purchase Intention of Consumers in Ho Chi Minh City, Vietnam

Nga Thi Hang PHAN,Thang Quyet Nguyen,Dung TRUONG,Nguyen The HUYNH 한국유통과학회 2019 The Journal of Asian Finance, Economics and Busine Vol.6 No.2

The paper aims to investigate the factors of brand equity affecting the purchase intention of car buyers in Ho Chi Minh City. The authors use qualitative method and quantitative research to study the matters, specifically using scales and data collected for Cronbach alpha reliability testing, analysizing the discovery factor of EFA, CFA and verifying the regression models through AMOS software with SEM linear modeling. The study proposes four factors: (1) brand awareness, (2) self-expression value, (3) perceived quality, (4) brand psychology impacting on the brand loyalty and intention to buy cars of customers. The results show that all four factors are statistically significant for positive brand loyalty and purchase willing. The results showed that brand loyalty positively affects consumers' intention to buy cars. Among the factors included in the study, the brand psychology is a new factor which developed by experts in the context of Vietnam. This is the first study in Vietnam to quantify clearly the element of "crowd psychology" affecting the interests and habits of Vietnamese consumers. This explains why Vietnamese consumers prefer brands that are familiar in the market and some new cars with nice models and colors suitable for Vietnamese psychology.

A Study on Particle Filter based on KLD-Resampling for Wireless Patient Tracking

Nga Ly-Tu,Thuong Le-Tien,Linh Mai 대한산업공학회 2017 Industrial Engineeering & Management Systems Vol.16 No.2

In this paper, we consider a typical health care system via the help of Wireless Sensor Network (WSN) for wireless patient tracking. The wireless patient tracking module of this system performs localization out of samples of Received Signal Strength (RSS) variations and tracking through a Particle Filter (PF) for WSN assisted by multiple transmit-power information. We propose a modified PF, Kullback-Leibler Distance (KLD)-resampling PF, to ameliorate the effect of RSS variations by generating a sample set near the high-likelihood region for improving the wireless patient tracking. The key idea of this method is to approximate a discrete distribution with an upper bound error on the KLD for reducing both location error and the number of particles used. To determine this bound error, an optimal algorithm is proposed based on the maximum gap error between the proposal and Sampling Important Resampling (SIR) algorithms. By setting up these values, a number of simulations using the health care system’s data sets which contains the real RSSI measurements to evaluate the location error in term of various power levels and density nodes for all methods. Finally, we point out the effect of different power levels vs. different density nodes for the wireless patient tracking.

Effects of Interlayer on Magnetotransports In Graphene-based Spintronic Devices

Nga T. Do,Youngrok Jang,Sijin Park,Chanyong Hwang,Tae Hee Kim 한국자기학회 2022 한국자기학회 학술연구발표회 논문개요집 Vol.31 No.2

Effect of UV-Curable Inkjet Printing Parameters on Physical, Low-Stress Mechanical, and Aesthetic Properties of Polypropylene Knitted Fabrics

Nga-wun Li,Chu-po Ho,Kit-lun Yick,Jin-yun Zhou 한국섬유공학회 2020 Fibers and polymers Vol.21 No.12

As the use of textile polypropylene (PP) fibers becomes more common in commercial textiles and sportswear, theinvestigation of the effects of UV-curable ink on the heat-sensitive PP knitted fabrics is crucial to optimize functional clothingdesign. This study investigated the effects of UV-curable ink on the heat-sensitive PP knitted fabrics when the ink was curedusing UV light at room temperature, to avoid degradation of the PP fabric by high temperature, and provided an alternativecoloring method for PP fabric used in sportswear. The influences of printing parameters such as the printing distance, numberof overprints, and color of ink on fabrics as well as aesthetic, physical, and low-stress mechanical properties in terms oftensile, bending, shearing, surface, and compression were systematically investigated. The results indicated that the physicalproperties and low-stress mechanical properties of PP fabrics printed with UV-curable ink were significantly affected by thenumber of overprints and the color of the prints, whereas the color appearance was affected mainly by the number ofoverprints and the printing distance. In terms of the fabric’s hand value, only 2HB and 2HG5 were significantly affected bythe number of overprints and the color of the prints, with the prediction rate exceeding 40 % among the low-stress mechanicalproperties. The fabric’s hand value was not significantly affected by the thin UV-cured ink film when compared with thefabric itself. Fabric printed in a color with the greatest lightness and the fewest overprints had the lowest fabric weight,thickness, and color difference (ΔE) towards the reference color, in addition to better bending recovery and resilienceproperties. The new knowledge from this study can provide an alternative coloring method for PP knitted fabric to increasethe design variety available to textile designers who use PP fabric. The results from this study contribute to the textile andknitwear design industry.