In vitro evaluation of the antioxidant and cytotoxic activities of constituents of the mangrove Lumnitzera racemosa Willd.

Nguyen Phuong Thao,Bui Thi Thuy Luyen,Chau Ngoc Diep,Bui Huu Tai,김은지,강희경,이상현,장해동,Nguyen The Cuong,Nguyen Van Thanh,Nguyen Xuan Cuong,Nguyen Hoai Nam,Chau Van Minh,김영호 대한약학회 2015 Archives of Pharmacal Research Vol.38 No.4

This study performed phytochemical and bioactiveassessments of the mangrove Lumnitzera racemosaWilld. leaves. Bioassay-guided fractionation of the methanolicextracts led to the identification of thirty-six compounds(1–36), their structures were elucidated using detailed NMRspectroscopic and MS analysis. The extracts, fractions, andthe isolated compounds were screened for potential antioxidantand cytotoxic activities. Antioxidant assays wereperformed using peroxyl radical-scavenging and reducingassays, whereas cytotoxicity was measured using MTTassays in HL-60 and Hel-299 cell lines. The methanolicextract, CH2Cl2 and n-BuOH fractions (10.0 lg/mL)exhibited potent antioxidant activity, with Trolox equivalent(TE) values of 24.94 ± 0.59, 28.34 ± 0.20, and27.09 ± 0.37 (lM), respectively. In addition, the isolatedcompounds exerted cytotoxic effects in a dose-dependentmanner; compounds 1 and 14 exhibited the most potentcytotoxicity in HL-60 cells, with IC50 values of 0.15 ± 0.29and 0.60 ± 0.16 lM, respectively. To clarify the mechanism(s) behind these cytotoxic effects, we measured thetime-dependent changes in apoptotic markers including thecondensation and fragmentation of nuclear chromatin, andthe downregulation of p-ERK1/2, p-AKT, and c-Myc levels.

The Impact of Foreign Ownership on Capital Structure: Empirical Evidence from Listed Firms in Vietnam

Van Diep NGUYEN,Quynh Nga DUONG 한국유통과학회 2022 The Journal of Asian Finance, Economics and Busine Vol.9 No.2

The study aims to probe the impact of foreign ownership on Vietnamese listed firms’ capital structure. This study employs panel data of 288 non-financial firms listed on the Ho Chi Minh City stock exchange (HOSE) and Ha Noi stock exchange (HNX) in 2015–2019. In this research, we applied a Bayesian linear regression method to provide probabilistic explanations of the model uncertainty and effect of foreign ownership on the capital structure of non-financial listed enterprises in Vietnam. The findings of experimental analysis by Bayesian linear regression method through Markov chain Monte Carlo (MCMC) technique combined with Gibbs sampler suggest that foreign ownership has substantial adverse effects on the firms’ capital structure. Our findings also indicate that a firm’s size, age, and growth opportunities all have a strong positive and significant effect on its debt ratio. We found that the firms’ profitability, tangible assets, and liquidity negatively and strongly affect firms’ capital structure. Meanwhile, there is a low negative impact of dividends and inflation on the debt ratio. This research has ramifications for business managers since it improves a company’s financial resources by developing a strong capital structure and considering foreign investment as a source of funding.

Numerical Study on Unified Seakeeping and Maneuvering of a Russian Trawler in Wind and Waves

Van Minh Nguyen,Thi Thanh Diep Nguyen,Hyeon Kyu Yoon,Young Hun Kim 한국해양공학회 2021 韓國海洋工學會誌 Vol.35 No.3

The maneuvering performance of a ship on the actual sea is very different from that in calm water due to wave-induced motion. Enhancement of a ship’s maneuverability in waves at the design stage is an important way to ensure that the ship navigates safely. This paper focuses on the maneuvering prediction of a Russian trawler in wind and irregular waves. First, a unified seakeeping and maneuvering analysis of a Russian trawler is proposed. The hydrodynamic forces acting on the hull in calm water were estimated using empirical formulas based on a database containing information on several fishing vessels. A simulation of the standard maneuvering of the Russian trawler was conducted in calm water, which was checked using the International Maritime Organization (IMO) standards for ship maneuvering. Second, a unified model of seakeeping and maneuvering that considers the effect of wind and waves is proposed. The wave forces were estimated by a three-dimensional (3D) panel program (ANSYS-AQWA) and used as a database when simulating the ship maneuvering in wind and irregular waves. The wind forces and moments acting on the Russian trawler are estimated using empirical formulas based on a database of wind-tunnel test results. Third, standard maneuvering of a Russian trawler was conducted in various directions under wind and irregular wave conditions. Finally, the influence of wind and wave directions on the drifting distance and drifting angle of the ship as it turns in a circle was found. North wind has a dominant influence on the turning trajectory of the trawler.

Experimental Study on Application of an Optical Sensor to Measure Mooring-Line Tension in Waves

Nguyen Thi Thanh Diep,박지원(Ji Won Park),Van Minh Nguyen,윤현규,Jung Joseph Chul,Lee Michael Myung Sub 한국해양공학회 2022 韓國海洋工學會誌 Vol.36 No.3

Moored floating platforms have great potential in ocean engineering applications because a mooring system is necessary to keep the platform in station, which is directly related to the operational efficiency and safety of the platform. This paper briefly introduces the technical and operational details of an optical sensor for measuring the tension of mooring lines of a moored platform in waves. In order to check the performance of optical sensors, an experiment with a moored floating platform in waves is carried out in the wave tank at Changwon National University. The experiment is performed in regular waves and irregular waves with a semi-submersible and triangle platform. The performance of the optical sensor is confirmed by comparing the results of the tension of the mooring lines by the optical sensor and tension gauges. The maximum tension of the mooring lines is estimated to investigate the mooring dynamics due to the effect of the wave direction and wavelength in the regular waves. The significant value of the tension of mooring lines in various wave directions is estimated in the case of irregular waves. The results show that the optical sensor is effective in measuring the tension of the mooring lines.

A Study on Sensitivity Analysis of the Hydrodynamic Derivatives on the Maneuverability Prediction of KVLCC2 in Shallow Water by Model Test

Van Minh Nguyen,Thi Thanh Diep Nguyen,Hyeon Kyu Yoon 한국항해항만학회 2020 한국항해항만학회지 Vol.44 No.2

In recent years, there have been concerted efforts toward predicting ship maneuvering in shallow water since the majority of ship’s accidents near harbors commonly occur in shallow and restricted waters. Enhancement of ship maneuverability at the design stage is crucial in ensuring that a ship navigates safely. However, though challenging, establishing the mathematical model of ship maneuvering motion is recognized as crucial toward accurately predicting the assessment of maneuverability. This paper focused on a study on sensitivity analysis of the hydrodynamic coefficients on the maneuverability prediction of KVLCC2 in shallow waters. Hydrodynamic coefficients at different water depths were estimated from the experimental results conducted in the square tank at Changwon National University (CWNU). The simulation of standard maneuvering of KVLLC2 in shallow waters was compared with the results of the Free Running Model Test (FRMT) in shallow waters from other institutes. Additionally the sensitivity analysis of all hydrodynamic coefficients was conducted by deviating each hydrodynamic derivative from the experimental results. The standard maneuvering parameters including turning tests and zig-zag maneuvers were conducted at different water depths and their effects on the standard maneuvering parameters were assessed to understand the importance of different derivatives in ship maneuvering in shallow waters.

Shadow Economy, Corruption and Economic Growth: An Analysis of BRICS Countries

Diep Van NGUYEN,My Tien Ha DUONG 한국유통과학회 2021 The Journal of Asian Finance, Economics and Busine Vol.8 No.4

The paper examines the impact of shadow economy and corruption, along with public expenditure, trade openness, foreign direct investment (FDI), inflation, and tax revenue on the economic growth of the BRICS countries. Data were collected from the World Bank, Transparency International, and Heritage Foundation over the 1991–2017 period. The Bayesian linear regression method is used to examine whether shadow economy, corruption and other indicators affect the economic growth of countries studied. This paper applies the normal prior suggested by Lemoine (2019) while the posterior distribution is simulated using Monte Carlo Markov Chain (MCMC) technique through the Gibbs sampling algorithm. The results indicate that public expenditure and trade openness can enhance the BRICS countries’ economic growth, with the positive impact probability of 75.69% and 67.11%, respectively. Also, FDI, inflation, and tax revenue positively affect this growth, though the probability of positive effect is ambiguous, ranging from 51.13% to 56.36%. Further, the research’s major finding is that shadow economy and control of corruption have a positive effect on the economic growth of the BRICS countries. Nevertheless, the posterior probabilities of these two factors are 62.23% and 65.25%, respectively. This result suggests that their positive effect probability is not high.

An Experimental Study on the Motion of the Floater Moored near Port in Waves Generated by a Ship

Thi Thanh Diep Nguyen,Van Minh Nguyen,윤현규,김영훈 한국항해항만학회 2020 한국항해항만학회지 Vol.44 No.5

In the past, various research on the effects of waves generated by ships has been investigated. The most noticeable effect of the waves generated by a passing ship is the increase of the hydrodynamic forces and the unwanted large motion of the moored ship and high mooring forces that occur. Thus, it is crucial to investigate the effect of the waves generated by the passing ship near port on the motion of the moored ship and the tension of the mooring lines. A model test was performed with virtual ship-generated waves in a square tank at CWNU (Changwon National University). The IMU (Inertial Measurement Unit) and Optical-based system were used to measure the 6DOF (Six Degrees of Freedom) motion of the moored floater. Additionally the tension of mooring lines were measured by the tension gauges. The effects of the wave direction and wave height generated by the virtual ship-generated waves on the motion of the moored floater were analyzed.

An Experimental Study on Hydrodynamic Forces of Korea Autonomous Surface Ship in Various Loading Conditions

Thi Thanh Diep Nguyen,Van Thuan Mai,이산,윤현규 한국항해항만학회 2022 한국항해항만학회지 Vol.46 No.2

Currently, shipping by sea is becoming common because of the low price and the safety of goods. The ship is designed as a larger vessel to meet the need of this development. In the design stage, the investigation of hydrodynamic forces acting on the ship hull is very important in predicting the ship's maneuverability. Given that the ship docks at various ports for loading or discharging goods, the ship usually operates in various loading conditions, depending on the site condition and other various factors. Hence, it is necessary to investigate the effect of the loading condition on the hydrodynamic forces acting on the ship, to most accurately determine the maneuverability of the ship. In this study, an experiment of Korea Autonomous Surface Ship (KASS) was conducted at the towing tank of Changwon National University to measure the hydrodynamic forces acting on the KASS. The loading condition considered in this experiment is determined based on the draft, which was decreased by 5% for each loading condition. The smallest draft is 85% of the design draft. The static test as Oblique Towing Test (OTT), Circular Motion Test (CMT), Circular Motion Test with Drift (CMTD) is performed in the various loading conditions. First, the hydrodynamic forces in the Oblique Towing test (OTT) are compared with the result of other institutes. Second, the hydrodynamic forces in various drift angle, yaw rate and loading conditions are measured. Finally, the influence of the loading conditions on the hydrodynamic coefficient is discussed.

Factors Affecting the Performance of Vietnamese Commercial Banks: Does Basel II Matter?

Duy Khang LE,Thi Minh Nhan TRAN,Van Diep NGUYEN 한국유통과학회 2022 The Journal of Asian Finance, Economics and Busine Vol.9 No.3

This paper examines the main factors affecting the bank performance under the Basel II implementation in Vietnam, a transitional economy in Asia. We pay special attention to the implementation duration of the Basel II convention and how it affects profitability. Thereby, we can evaluate the effectiveness of Basel II in the whole system according to the roadmap to 2020. We employ the panel data regression method to analyze a sample of 300 bank-year observations from 25 commercial banks during the 2008–2019 period. Our empirical findings show that the size of the bank, net interest margin, state ownership, and Basel II convention have positive effects on bank profitability. However, our empirical findings indicate that bank age and branch number negatively reduce bank performance. Finally, our results indicate that commercial banks earn extra profit from delaying the implementation of Basel II. However, commercial banks will encounter higher credit, and operational risks arising from delaying the implementation of Basel II standards. Therefore, our study contributes to the insights into the bank’s management to enhance profitability, especially after implementing Basel II in a transitional economy. Finally, our study also provides policy implications for bank managers and banking supervisory to maintain the sustainable development of the banking system.

The Impact of Foreign Ownership on Firm Performance

Quynh Nga DUONG,Thanh Binh VU,Thi-Phuong VO,Ngoc Hoan NGUYEN-LE,Van Diep NGUYEN 한국유통과학회 2021 The Journal of Asian Finance, Economics and Busine Vol.8 No.6

The purpose of the research examines the relationship between foreign ownership and listed firms’ performance in Vietnam. This study employs an extensive set of panel data comprising 288 non-financial listed Vietnamese firms, over a period from 2015 to 2019 taken for analysis. The results show that the higher the foreign ownership ratio, the higher the performance, however, the relationship between foreign ownership and firm’s performance is U-shaped. In contrast, when the foreign ownership ratio is becoming too high, it will reduce the firm’s performance and firm size, liquidity, financial leverage, capital intensity, and growth opportunities. Furthermore, we find that foreign ownership and performance are linked by an inverted U-shaped relationship. A firm’s performance increases with greater foreign ownership up to the range of 36.26%, and declines thereafter. The paper also found positive effects of firm size and growth opportunities, and an inverse relationship between liquidity, financial leverage and capital intensity, and firm’s performance. This study has several implications for the enhancement of information and understanding of the foreign ownership as it sheds light on the foreign ownershipfirm’s performance relationship. Moreover, the study findings contribute to the literature concerning the ownership structure in the context of developing countries.