A Study on Factor that Effect on Consumer’s Behaviour on Cross-Border E-Commerce in Vietnam - Ho Chi Minh City

Dao,Duy Thang,Hyun,In-Gyou 한국유통과학회 2019 KODISA ICBE (International Conference on Business Vol.2019 No.-

Vietnam E-commerce has been used and developed 10 years ago but recently, with removing tariff barriers, Vietnam’s customer can easily buy almost thing in the foreign web-site. However, little research has been done to study how to customer’s using intention on across national borders. This study aims to find the factors that effect to customer’s using intention on foreign direct online shopping. A conceptual model is developed from the perspectives of customer’s trust and value. We also examine the impact of information’s signal, security and safe, country image on customer’s trust, as well as the impact of benefits, innovation, cost on customer’s perceived value. This study use an online survey to make questionnaire about the factor and use the answer to test the research model. Our findings can help researchers and practitioners understand the barriers and behaviour of Ho Chi Minh City’s customers to cross-border e-commerce and devise strategies to make profit.

Ultrasonic Vibration Assisted Cutting of Nomex Honeycomb Core Materials

Dao‑Hui Xiang,Bang‑Fu Wu,Yun‑Long Yao,Bo Zhao,Jin‑Yuan Tang 한국정밀공학회 2019 International Journal of Precision Engineering and Vol.20 No.1

Nomex honeycomb core materials have been widely used in the aviation industry due to their special structure and performance. Conventional high-speed machining have resulted in the poor machinability of the honeycomb core so that the ultrasonic machining technology was applied. The kinematic characteristics in the ultrasonic vibration assisted cutting process were analyzed according to the movement of the sharp tool. Based on slide effect, a cutting force model was proposed to study the relationship between cutting parameters and cutting force. Ultrasonic vibration assisted cutting and ordinary cutting tests of Nomex honeycomb core material were conducted by considering feed rate, the inclined angle and the deflected angle. Besides, the effects of cutting parameters on machined surface quality of honeycomb core wall were studied. The test results show that slide effect caused by ultrasonic vibrations can reduce cutting resistance compared with ordinary cutting. The developed cutting force model can be applied to evaluated the cutting force in the ultrasonic vibration assisted cutting of Nomex honeycomb core material. The inclined angle has a great influence on the cutting force during ultrasonic vibration assisted cutting. High-speed reciprocating sliding action can effectively cut aramid fibers so that burrs and tearing defects of the incision have been greatly improved under condition of ultrasonic vibration assisted cutting.

Influence of Rain Gauge Density and Temporal Resolution on the Performance of Conditional Merging Method

Dao,Duc Anh,Kim,Soohyun,Kim,Tae-Woong,Kim,Dongkyun 한국방재학회 2019 한국방재학회논문집 Vol.19 No.6

본 연구는 in-situ 강우자료와 레이더자료를 병합하는 조건부 합성(CM)기법의 성능 평가를 목표로 한다. 합성방법은 다음 단계를 통해 처리된다. (1) 정규 크리깅(OK) 기법은 관측소와 레이더 기반 크리깅 강우장을 얻기 위해 적용한다. (2) 보정 강우장은 원래 레이더 강우장에서 레이더기반 크리깅 강우장의 차로 계산한다. (3) 합성강우량은 관측소기반 크리깅 강우장에 보정 강우장을 더하여 도출한다. 분석결과는 CM기반 강우장이 조사된 모든 33개의 10분 강우장 중 22개 사례에 대해 관측소기반 강우장보다 더 정확한 것으로 나타났다. CM 방법과 관측소기반 OK기법의 상관계수는 각각 0.63과 0.83 그리고 0.01과 0.74 사이 값을 보인다. 두 방법의 성능은 관측소 밀도가 높고 시간해상도가 낮을수록 향상되었다. OK기법의 성능은 관측소 밀도에 더 민감하고, CM 기법의 성능은 시간해상도에 더 민감한 것으로 나타났다. 또한, 기존 관측소 밀도가 100 km2 당 1개 일 때, 관측소를 추가하면 두 방법의 성능이 크게 향상되었다. 관측소 증가에 의한 강우량 측정 개선 정도는 관측소 개수가 100 km2 당 4개 이상에 도달할 시 효과가 미미한 것으로 나타났다. This study aims to evaluate the performance of conditional merging (CM) technique to merge radar and in-situ rain gauge data. The merging method contains the following steps: (1) the ordinary kriging(OK) technique is applied to obtain the gauge-only and radar-only kriged rainfall fields; (2) the correction field is calculated by subtracting the radar-only kriged rainfall field from the original radar field; (3) the composite rainfall is derived by adding the correction field to the gauge-only kriged field. We investigated 33 10-min rainfall fields; there were 22 instances where the CM-based rainfall fields were more accurate than the gauge-only fields. The correlation coefficients of the CM and the gauge-only OK methods varied between 0.63 and 0.83, and 0.01 and 0.74 respectively. The performance of both methods improved with greater gauge density and coarser temporal resolution. Furthermore, the OK and CM techniques’performances were more sensitive to gauge density and temporal resolution respectively. We also found that the addition of gauge significantly improved the performance of both methods when the existing gauge density is approximately 1 gauge/100 km2. However, this effect is absent when the density reaches 4 gauges/100 km2.

당송(唐宋)시기 도통(道統)내용의 전환 -당말(唐末)에서 북송(北宋)시기 도의 전승 내용에 관한 담론을 중심으로-

임명희 ( Myung Hee Lim ) 한국철학사연구회 2013 한국 철학논집 Vol.0 No.36

住居移動의 理念的 모델 定立

韓大鉉 강릉대학교 영동산업문제연구소 1985 産經論叢 Vol.4 No.-

Stewardship Theory and Information on Family Firm Performance in Vietnam

Thi Thanh Binh DAO(Thi Thanh Binh DAO ),Linh Chi HOANG(Linh Chi HOANG ) 한국유통과학회 2022 유통과학연구 Vol.20 No.12

Purpose: The paper contributes to the existing literature on Vietnamese corporate governance and firm performance with a focus on listed family firms and the use of a more suitable econometric framework to analyze firm performance. The study investigates how family firm performance is affected by corporate governance under the standpoint of stewardship theory in Vietnam. Research design, data and methodology: With the use of different measures for firm performance (Tobin’s Q, ROA, and ROE), regression models were estimated using Generalized Least Square (GLS) method on a panel data of a total of 113 listed companies during the five-year period from 2015 to 2019. Results: We found that family ownership as the main characteristic of the stewardship theory affects family firms positively. In addition, several other characteristics in corporate governance as board composition (board independence, board audits, and board committees), CEO (age and tenure) and firm characteristics (size, age, expansion, and annual sales) showed significant impacts on firm performance. Our findings also suggest that family firm performance can be either positively or negatively affected based on the characteristics of corporate governance. The findings can help companies evaluate the significance of corporate governance through deciding board structure and the selection of CEOs to match family firm characteristics. It also gives insights for investors, rating agencies, and policymakers for relevant purposes.

Optimized surface passivation of n and p type silicon wafers using hydrogenated SiN_x layers

Dao, V.A.,Heo, J.,Kim, Y.,Kim, K.,Lakshminarayan, N.,Yi, J. North-Holland 2010 Journal of non-crystalline solids Vol.356 No.50

We have investigated surface passivation of n and p type silicon wafers, obtained by controlling silicon-hydrogen bonding and fixed charge densities with the use of hydrogenated SiN<SUB>x</SUB> films. The hydrogenated SiN<SUB>x</SUB> films were deposited by single PECVD at 13.56MHz with SiH<SUB>4</SUB>/NH<SUB>3</SUB> gas mixture. The hydrogenated SiN<SUB>x</SUB> films of refractive indices 2.55-1.92 and high optical band-gap (>3.1eV) were obtained by varying the hydrogenated SiN<SUB>x</SUB> film composition. The fixed charge densities, hydrogen-bonding and carrier lifetime performance in n and p type silicon wafer were analyzed. The highest fixed positive charge of 2.66x10<SUP>12</SUP> (cm<SUP>-2</SUP>) was for the hydrogenated SiN<SUB>x</SUB> film composition of 1.21. Fourier transform infrared spectroscopy measurement was carried out to evaluate the bonding concentration of Si-H and N-H. The minority carrier lifetimes of the hydrogenated SiN<SUB>x</SUB> passivated silicon wafers were up to 153μs and 84μs for p and n type, respectively. Mechanism of surface passivation depends on the type of silicon wafer. The higher Si-H bond density is the key point of n type passivation quality. The large fixed positive charge is used to measure p type passivation quality.

Converter-level Reliability of Wind Turbine with Low Sample Rate Mission Profile

Dao Zhou,Frede Blaabjerg 전력전자학회 2019 ICPE(ISPE)논문집 Vol.2019 No.5

The thermal dynamics of power semiconductors and power capacitors are closely related to the reliability and the cost of power electronic converter. However, the component loading in a wind turbine system is disturbed by many factors of the converter system, which is present at various time-constants from microseconds to years. In the case of a mission profile with 1-hour sample rate, the circuit model, loss model, and thermal model of the active power switches and passive capacitors are described and presented. The percentile lifetime of a single component can be predicted according to the long-term electro-thermal profile, and the Weibull function based time-to-failure distribution of the active component and passive component can be obtained. In a 2 MW wind turbine system, it can be seen that the dc-link capacitor bank dominates the converter-level reliability.

Benefit of the Drinking Water Supply System in Office Building by Rainwater Harvesting: A Demo Project in Hanoi, Vietnam

Dao, Anh-Dzung,Nguyen, Viet-Anh,Han, Mooyoung Korean Society of Environmental Engineers 2013 Environmental Engineering Research Vol.17 No.1

Vietnam is a developing country with the rate around 5%-6% per year, especially in urban areas. Rapidly developed urban areas lead to stress for infrastructure and the water supply is also stressed. In Hanoi city, total water capacity from the manufactories is around one million cubic meters per day and almost the entire main water source is groundwater but it is not enough to supply all of Hanoi's people, especially in the summer. A demo project is implemented in Hanoi University of Civil Engineering (HUCE) to produce drinking water by using the rainwater and membrane system and supply for people. In this project, rainwater is collected on the rooftop of the lecture building with an area of around $500m^2$ and $100m^3$ volumetric rainwater tanks. Afterwards, the rainwater is treated by the micro-membrane system and supplied to the tap water. Total cost for construction, technology and operation in the first year is around USD 48,558. In the long-term (15 yr) if HUCE invests in the same system, with $20m^3$ volumetric storage tank, it can provide drinking water for 500 staffs in every year. The cost of investment and operation for this system is lower than 30% compared to buying bottled water with the price USD 1.8/bottle. The drinking water parameters after treatment are pH, 7.3-7.75; turbidity, 0.6-0.8 NUT; total dissolved solids, 60-89 mg/L; coliform, 0; heavy metal similar with water quality in the bottle water in Vietnam.

Magnetic Properties and Impedance Spectroscopic Studies of Multiferroic Bi<SUB>1-x</SUB>Nd<SUB>x</SUB>FeO₃ Materials

Dao Viet Thang,Du Thi Xuan Thao,Nguyen Van Minh 한국자기학회 2016 Journal of Magnetics Vol.21 No.1

Nd-doped BiFeO₃ materials were synthesized via a sol–gel method. The crystal structure, magnetic properties, and complex impedance spectroscopy of multiferroic Bi1-xNdxFeO₃ (BNFO) materials were investigated by Xray diffraction (XRD), Raman scattering, vibrating sample magnetometer (VSM), and complex impedance spectroscopy. Our results show that the lattice crystal constants (a, c) and the ratio c/a of BNFO materials decreased with increasing Nd concentration. All samples exhibited weak ferromagnetism at room temperature, and the magnetization of samples was enhanced by the presence of Nd<SUP>3+</SUP> ions. There was an enhancement in the spontaneous magnetization of BFO with increasing Nd concentration, which is attributable to the collapse of the spin cycloid structure.