Modeling of Doppler Power Spectrum for Underwater Acoustic Channels

Do Viet Ha,Nguyen Van Duc,Nguyen Quoc Khuong 한국통신학회 2017 Journal of communications and networks Vol.19 No.3

In this paper, we propose a closed-form expression of Doppler power spectrum model for underwater acoustic (UWA) channels. Using the geometry model for shallow UWA channels, we analyze the theoretical background of Doppler effects generated by the transmitter/receiver (Tx/Rx) movement, or by the motion of sea-surface. As a result, the Doppler power spectrum can be modeled as a summation of the Spike-shape and the Gaussian-shape. The Spike-shape presents the Doppler component from the Tx/Rx movement, while the Gaussian-shape presents the Doppler component from the sea-surface motion. The proposed model is validated through curve fitting with the Doppler power spectrum measurement results of a real shallow UWA channel in Halong bay, Vietnam. The optimal parameters of the proposed model are derived from the measurement results by applying an optimization algorithm called the Lp-norm method. The curve fitting results show that our proposed model matches well with the measurements. Therefore, the proposed Doppler model can accurately describe the Doppler effects for shallow UWA channels. The proposed model can be used to design UWA channel simulators for the performance evaluation of UWA communication systems.

New execution model for CAPE using multiple threads on multicore clusters

Do, Xuan Huyen,Ha, Viet Hai,Tran, Van Long,Renault, Eric Electronics and Telecommunications Research Instit 2021 ETRI Journal Vol.43 No.5

Based on its simplicity and user-friendly characteristics, OpenMP has become the standard model for programming on shared-memory architectures. Checkpointing-aided parallel execution (CAPE) is an approach that utilizes the discontinuous incremental checkpointing technique (DICKPT) to translate and execute OpenMP programs on distributed-memory architectures automatically. Currently, CAPE implements the OpenMP execution model by utilizing the DICKPT to distribute parallel jobs and their data to slave machines, and then collects the results after executing these distributed jobs. Although this model has been proven to be effective in terms of performance and compatibility with OpenMP on distributed-memory systems, it cannot fully exploit the capabilities of multicore processors. This paper presents a novel execution model for CAPE that utilizes two levels of parallelism. In the proposed model, we add another level of parallelism in the form of multithreaded processes on slave machines with the goal of better exploiting their multicore CPUs. Initial experimental results presented near the end of this paper demonstrate that this model provides significantly enhanced CAPE performance.

Factors Affecting Tourists’ Satisfaction in Associated Tourism Chains

Ha NGUYEN VAN,Thi Kim Hao DO,Thi Viet Ha NGUYEN,Ngoc Tien NGUYEN 한국유통과학회 2021 The Journal of Asian Finance, Economics and Busine Vol.8 No.6

Tourism is an interdisciplinary, inter-regional, inter-territory integrated economy; therefore, the construction of an associated tourism chain will help localities in the region take greater advantage of tourism resources and tourism products to meet the diverse needs of visitors (UNWTO, 2013). This research seeks to identify the factors affecting the satisfaction of tourists in the associated tourism chain in four central provinces of Vietnam – Binh Dinh, Phu Yen, Gia Lai, and Dak Lak. The study surveyed 1,361 tourists who have participated in an affiliated tour chain in these provinces during the March–April 2020 period. The survey was conducted online with the help of Google Form and the data collected were processed using descriptive statistics, exploratory factor analysis, and regression analysis. The research results show that two main factors are affecting the satisfaction of tourists in the associated tourism chain in the above regions, namely, (i) tourism resources (cultural beauty in localities in the associated tourism chain, local cuisine in the affiliated travel chain, natural landscapes/local attractions in the linked tourism chain, etc.); and (ii) tourism environment (the climate in localities in the associated tourism chain, the clean and fresh environment in localities in the associated tourism chain, etc.).

Outcomes of liver transplantation for hepatocellular carcinoma: Experiences from a Vietnamese center

Khai Viet Ninh,Dang Hai Do,Trung Duc Nguyen,Phuong Ha Tran,Tuan Hoang,Dung Thanh Le,Nghia Quang Nguyen 한국간담췌외과학회 2024 Annals of hepato-biliary-pancreatic surgery Vol.28 No.1

Backgrounds/Aims: Liver transplantation (LT) provides a favorable outcome for patients with hepatocellular carcinoma (HCC) and was launched in Vietnam in 2004. In this study, we evaluated the short-term and long-term outcomes of LT and its risk factors. Methods: This retrospective study analyzed HCC patients who underwent LT at Viet Duc University hospital, Vietnam, from 01/2012–03/2022. The following data were gathered: demographics, virus infection, tumor characteristics, alpha-fetoprotein (AFP) level, Child-Pugh and MELD scores, selection criteria, type of LT, complications, 30-day mortality, and disease-free and overall survival (DFS and OS). Results: Fifty four patients were included, the mean age was 55.39 ± 8.46 years. Nearly 90% had hepatitis B virus-related HCC. The median (interquartile range) AFP level was 16.2 (88.7) ng/mL. The average MELD score was 10.57 ± 5.95; the rate of Child-Pugh A and B were 70.4% and 18.5%, respectively. Nearly 40% of the patients were within Milan criteria, brain-dead donor was 83.3%. Hepatic and portal vein thrombosis occurred in 0% and 1.9%, respectively; hepatic artery thrombosis 1.9%, biliary leakage 5.6%, and postoperative hemorrhage 3.7%. Ninety-day mortality was 5.6%. Five-year DFS and OS were 79.3% and 81.4%, respectively. MELD score and Child- Pugh score were predictive factors for DFS and OS (p < 0.05). In multivariate analysis, Child-Pugh score was the only significant factor (p < 0.05). Conclusions: In Vietnam, LT is an effective therapy for HCC with an acceptable complication rate, mortality rate, and good survival outcomes, and should be further encouraged.

Dielectrophoresis Microfluidic Enrichment Platform with Built-In Capacitive Sensor for Rare Tumor Cell Detection

Loc Quang Do,Ha Tran Thi Thuy,Tung Thanh Bui,Van Thanh Dau,Ngoc-Viet Nguyen,Trinh Chu Duc,Chun-Ping Jen 한국바이오칩학회 2018 BioChip Journal Vol.12 No.2

The manipulation and detection of rare cells are important for many applications in early disease diagnosis and medicine. This study presents a dielectrophoresis (DEP) microfluidic enrichment platform combined with a built-in capacitive sensor for circulating tumor cell detection. The microchip is composed of a lollipop-shaped gold microelectrode structure under a polydimethylsiloxane chamber. A prototype of the device was fabricated using standard micromachining technology. With the proposed device, target cells (in this study, A549 non-small human lung carcinoma and S-180 sarcoma cell lines) are firstly guided toward the center of the working chamber via DEP forces. Then, the target cells are captured by an electrode immobilized by anti-EGFR, which has high affinity toward the target cells. After the cell concentration process, the differential capacitance is read to detect the presence of the target cells. Numerical simulations and measurement experiments were performed to demonstrate the high sensitivity of differential capacitive sensing. The obtained results show high sensitivity for S-180 cell detection (3 mV/cell). The proposed platform is suitable for rapid cancer diagnoses and other metabolic disease applications.

The Impact of Vietnam’s New Rural Development Program on Rural Household Income: Cross-sectional Evidence Covering Communes That Hosted Korea’s Saemaul Undong Program

Manh Hung Do,비엣 흥 응웬(Viet Hung Nguyen),투하 응웬 티(Thu Ha Nguyen Thi),한 호앙 티(Hanh Hoang Thi),프엉 투 응웬 티(Phuong Thu Nguyen Thi) 영남대학교 박정희새마을연구원 2018 새마을학연구 Vol.3 No.2

베트남의 1986년도 정치경제 개혁, 즉 도어머이(Doi Moi)는 베트남의 경제를 개방적 사회주의경제로 전환시켰으며, 이를 계기로 베트남 경제는 획기적으로 근대화되었다. 그러나 이 과정에서 급속한 도시화는 도농 간 불균형을 가져왔으며, 이 도농 간 격차를 줄이기 위해 베트남 정부는 2006년에 새농촌개발(NRD) 프로그램을 도입하기에 이르렀다. 이 프로그램은 농촌 지역의 사회기반시설의 확충과 생활환경의 개선, 생산 활동의 종합적 발전, 소득증대, 농민들의 육체적ㆍ정신적 건강 증진 등을 목표로 하고 있었다. 이 논문의 주된 목적은 NRD 프로그램의 시행이 NRD의 궁극적 목적 중 하나인 농가소득 증대에 미치는 영향에 대한 과학적 증거를 제시하는 데 있다. 또한 이와 더불어 새마을운동의 시범사업을 실시한 지역과 그렇지 않은 지역 간에 소득 증대에서 차이가 있는가를 다중회귀분석을 통해 밝혀보고자 한다. 분석 결과는 NRD의 시행이 상당히 긍정적 결과를 가져왔으며 코민 수준에서 농가소득 증대와 생활환경의 개선에 중요한 영향을 미쳤다는 것을 보여주었다. 또한 도로 건설, 전기 도입, 주민 역량 강화, 제도의 발전 등이 농가소득 증대에 큰 영향을 미쳤음을 확인했다. 회귀분석의 결과는 또한 새마을 사업을 시행하고 있는 코뮌들이 그렇지 않은 코뮌에 비해 연소득이 1200만 동(미화530달러) 더 많다(또는 41.8% 더 높다)는 것을 보여주었다. The economic and political reform of Vietnam in 1986 (the Doi Moi) has transformed its economy positively and significantly into an open socialist-oriented market economy. This caused a dramatic change of Vietnam’s economy towards modernization. However, the urbanization process created an unbalanced development between the urban and rural regions. To solve the gaps between these regions, the government of Vietnam firstly introduced the New Rural Development (NRD) program in 2006 to encourage and mobilize a revolutionary and campaign to improve local infrastructure, living condition, comprehensive development of related-production activities in rural regions, as well as increase income, and improve physical and mental health of people living in rural communities. One of the main purposes of this research paper is aimed at providing a scientific evidence for justifying whether the NRD implementation could have an impact on rural households’ income, one of the ultimate goals of the NRD, and examining the difference of incomes between Saemaul Undong (SU)-piloted provinces with the other provinces by employing a multiple regression model. The analysis results show that the NRD implementation has shown positive results and significant impacts on increasing rural households’ income and improving living conditions at the communal levels. Criteria such as road development, access to electricity, capacity building, and institutional development have significantly influenced on the households’ income. The regression model also indicates that the communes currently implementing SU pilots have a better annual income of 12 million VND (~US$ 530) or 41.8% higher than the other communes.

Physicochemical properties of native and partially gelatinized high-amylose jackfruit (<i>Artocarpus heterophyllus</i> Lam.) seed starch

Tran, Phuong Lan,Nguyen, Dang Hai Dang,Do, Viet Ha,Kim, Young-Lim,Park, Sunghoon,Yoo, Sang-Ho,Lee, Suyong,Kim, Yong-Ro Elsevier 2015 LWT- Food science and technology Vol.62 No.2

<P><B>Abstract</B></P> <P>Jackfruit seed starch (JFSS) cultivated in Vietnam had a high amylose content (∼44%). Differential scanning calorimetry thermogram of JFSS consisted of two separate endothermic peaks with distinct onset and conclusion temperatures. When JFSS was heated at 70?°C, the first endothermic peak disappeared, whereas the second endotherm remained. The partially-gelatinized JFSS still possessed A-type X-ray diffraction pattern. SEM images showed that the rim of the starch granule at the hollow bottom of the bell shape first melted during the partial gelatinization at 70?°C. Both native and partially-gelatinized JFSS produced soft and highly elastic gels, but their moduli differed slightly. Additionally, the partially-gelatinized JFSS was successfully used to produce genistin–cycloamylose (CA) and amylose–lysolecithin complexes with and without 4-α-glucanotransferase. Water sorption isotherms of partially gelatinized JFSS showed higher water-holding capacity than that of the native starch.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Vietnamese Jackfruit seed starch had two separate DSC gelatinization endotherms. </LI> <LI> JFSS heated at 70?°C showed one endotherm with crystallinity and granular integrity. </LI> <LI> Vietnamese Jackfruit seed starch produced a soft but highly elastic gel. </LI> <LI> High amylose JFSS was used to enzymatically produce genistin-cycloamylose complex. </LI> </UL> </P>

Screening of Vietnamese Medicinal Plants for Cytotoxic Activity

Nguyen Bich Thu,Trinh Nam Trung,Do Thi Ha,Nguyen Minh Khoi,Tran Viet Hung,Tran Thi Hien,Yim Namhui,배기환 한국생약학회 2010 Natural Product Sciences Vol.16 No.1

Thirty-two methanol extracts of thirty-one Vietnamese medicinal plants were evaluated for the cytotoxic activity against five human cancer cell lines, including A549, MCF-7, HT 1080, Huh-7, and HepG2. Of these, the nine extracts of Acanthopanax trifoliatus (4), Acanthopanax gracilistylus (5), Siegesbeckia orientalis (10), Betula alnoides (11), Passiflora edulis (18), Zanthoxylum simulans (leaf, 23), Adenosma caeruleum (26), Solanum verbascifolium (29), and Alpinia malaccensis (31), exhibited high potent cytotoxic activity showing a certain degree of selectivity against the different cell types, with IC50 values ranging from 2.1 to 3.8 mg/mL.

Zanthoxylum rhetsa Stem Bark Extract Inhibits LPS-induced COX-2 and iNOS expression in RAW 264.7 Cells via the NF-kB Inactivation

Nguyen Bich Thu,Trinh Nam Trung,Do Thi Ha,Nguyen Minh Khoi,Nguyen Viet Than,Thipthaviphone Soulinho,Nguyen Hai Nam,Tran Thi Phuong,배기환 한국생약학회 2010 Natural Product Sciences Vol.16 No.4

The methanol extract of Zanthoxylum rhetsa (MZRR) were evaluated for its ability to suppress the formation of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) in lipopolysaccharide (LPS)-activated RAW 264.7 macrophages. MZRR presented an inhibition of LPS-induced production of nitric oxide (NO) and prostaglandin E2 (PGE2) in RAW 264.7 macrophages. Western blotting and RT-PCR analyses demonstrated that MZRR significantly inhibited the protein and mRNA expressions of iNOS and COX-2 in LPS-activated macrophages in a dose-dependent manner. LPS-induced COX-2, iNOS, and nuclear factor kappa beta (NF-kB) activity were also decreased in the presence of MZRR. The production of tumor necrosis factor-a (TNF-a), the mRNA expression levels of pro-inflammatory cytokines, including TNF-a and IL-1b, were reduced after MZRR administration in a dose dependent-manner. These results suggest that the MZRR extract involved in the inhibition of iNOS and COX-2 via the NF-kB pathway, revealing a partial molecular basis for anti-inflammatory properties of the MZRR extract.

Chemical Composition of Clausena lansium (Lour.) Skeels Leaves and Antifungal Activity

Vu Duc Nam,Fujimatsu Teruhisa,Takigawa Hirofumi,Kusuoku Hiroshi,Nguyen Minh Khoi,Le Viet Dung,Do Thi Ha,Hashimoto Hiroshi 한국생약학회 2016 Natural Product Sciences Vol.22 No.1

The first study on chemical constituents and biological activities of Clausena lansium (Lour.) Skeels (Rutaceae) growing in Vietnam has been done. Phytochemical investigation of n-hexane extract led to the isolation of five compounds: dihydroindicolactone (1), 8-geranyloxy psoralen (2), imperatorin (3), heraclenol (4) and indicolactone (5), in which this is the first report on the presence of dihydroindicolactone (1). Their structures were elucidated based on LC/MS/NMR hyphenated techniques as well as comparison with those of literature data. The n-hexane extract and its subfractions, ethanol 95% extract and several isolated compounds were evaluated for antifungal activity.