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.

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.

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.

Hydrogenated Amorphous Silicon Layer Formation by Inductively Coupled Plasma Chemical Vapor Deposition and Its Application for Surface Passivation of p-Type Crystalline Silicon

Dao, Vinh Ai,Duy, Nguyen Van,Heo, Jongkyu,Choi, Hyungwook,Kim, Youngkuk,Lakshminarayan,Yi, Junsin IOP Publishing 2009 Japanese journal of applied physics Vol.48 No.r6

Anti-Obesity and Hypolipidemic Effects of Ethanolic Extract from Alpinia officinarum Hance (Zingiberaceae) in Rats Fed High-Fat Diet

Dao-Zong Xia,Xin-Fen Yu,Hui-Ming Wang,Qi-Ya Ren,Bing-Mei Chen 한국식품영양과학회 2010 Journal of medicinal food Vol.13 No.4

To investigate the anti-obesity and hypolipidemic effects of Alpinia officinarum ethanolic extract (AOE) for the first time, anti-obesity models in vivo were used. Ten male Sprague-Dawley rats were fed normal control diet (NC); other groups of rats were fed a high-fat diet (HFD) with or without different proportions of AOE (AOE-1, 3%; AOE-2, 5%) for 6 weeks to examine feed intake, body and adipose tissue weight, serum total cholesterol (Total-C), triacylglycerol (TG), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), and leptin levels, alanine aminotransferase (ALT) and aspartate aminotranferase activities, hepatic Total-C and TG levels, and the pathological changes in liver and epididymal adipose tissues. Interestingly, feed intakes among the experimental groups were not significantly different. Body weight gains were significantly lowered in the AOE-1 and AOE-2 groups compared with the HFD group (P<.05) and near to the level of the NC group. AOE also improved the lipid profile in serum and the pathological changes in liver and adipose tissue and decreased the relative weights of epididymal and perirenal white adipose tissues. They improved lipid profile by lowering serum Total-C, TG, and LDL-C concentrations, leptin content, and the atherogenic index compared with the HFD group. The HDL-C concentration and the ratio of HDL-C/Total-C significantly increased compared with those of the HFD group. The serum ALT activity of the AOE-2 group was notably lower than that of the HFD group. Our data suggest that AOE can be considered as an anti-obesity agent that is effective for suppressing body weight gain and decreasing lipid profile.

A microfluidic enrichment platform with a recombinase polymerase amplification sensor for pathogen diagnosis

Dao, Thuy Nguyen Thi,Lee, Eun Yeong,Koo, Bonhan,Jin, Choong Eun,Lee, Tae Yoon,Shin, Yong Elsevier 2018 Analytical Biochemistry Vol.544 No.-

<P><B>Abstract</B></P> <P>Rapid and sensitive detection of low amounts of pathogen in large samples is needed for early diagnosis and treatment of patients and surveillance of pathogen. In this study, we report a microfluidic platform for detection of low pathogen levels in a large sample volume that couples an Magainin 1 based microfluidic platform for pathogen enrichment and a recombinase polymerase amplification (RPA) sensor for simultaneous pathogenic DNA amplification and detection in a label-free and real-time manner. Magainin 1 is used as a pathogen enrichment agent with a herringbone microfluidic chip. Using this enrichment platform, the detection limit was found to be 20 times more sensitive in 10 ml urine with <I>Salmonella</I> and 10 times more sensitive in 10 ml urine with <I>Brucella</I> than that of real-time PCR without the enrichment process. Furthermore, the combination system of the enrichment platform and an RPA sensor that based on an isothermal DNA amplification method with rapidity and sensitivity for detection can detect a pathogen at down to 50 CFU in 10 ml urine for <I>Salmonella</I> and 10<SUP>2</SUP> CFU in 10 ml urine for <I>Brucella</I> within 60 min. This system will be useful as it has the potential for better diagnosis of pathogens by increasing the capture efficiency of the pathogen in large samples, subsequently enhancing the detection limit of pathogenic DNA.</P>

Effect of Torrefied Biomass on the Physicochemical Properties of Biocomposites Blending with Polylactic Acid and Torrefied Biomass

( Dao Kha Giang ),( Se-eun Ban ),( Chan-duck Jung ),( June-ho Choi ),( Hyo-lin Seong ),( Hoyong Kim ),( Jae-won Lee ) 한국목재공학회 2022 한국목재공학회 학술발표논문집 Vol.2022 No.1

In this study, the physicochemical properties of torrefied biomass was investigated depending on torrefaction temperature and particle size (< 100 mesh and > 100 mesh). The effect of torrefied biomass addition to the hydrophobicity and mechanical properties of biocomposites was evaluated by thermal, morphology, and mechanical analysis for food and beverages packaging application. The hemicellulose (mannan and xylan) content of the biomass decreased with increasing torrefaction temperature. Most mannan of larch and xylan of yellow poplar were degraded at sever condition (280℃ for 50 min). The biomass color was darker with increasing torrefaction temperature regardless species. Carbon content of larch (49.0%) was higher than that of yellow poplar (46.6%) and it was gradually increased with increasing torrefaction temperature. The tensile strength of PLA was 68.0 MPa, and the value decreased in all biocomposite. The tensile strength of biocomposite containing untreated biomass was decreased for both biomass regardless particle size used in this study. In the <100 mesh particle size, the tensile strength of biocomposite containing torrefied biomass decreased compare to that of untreated biomass.