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.

Effect of a Towed Trawl on the Hydrodynamic Forces of Acting on the Fishing Vessel

Thi Thanh Diep Nguyen,Hoang Thien Vu,Hyeon Kyu Yoon 한국항해항만학회 2025 한국항해항만학회 학술대회논문집 Vol.2025 No.5

Fishing vessels experience significant hydrodynamic changes when towing a trawl, affecting their stability, maneuverability, and fuel efficiency. Understanding these effects is crucial for optimizing vessel performance and ensuring safe and efficient fishing operations. This study investigates the influence of a towed trawl on the hydrodynamic forces acting on a fishing vessel. The interaction between the vessel and the trawl introduces additional resistance, affects maneuverability, and alters the overall dynamic behavior of the system. To analyze these effects, a model test was conducted to predict the hydrodynamic forces acting on the fishing vessel by towing a trawl behind the model ship. The Antarctic krill trawl was selected as the target trawl in this study. A series of captive model tests such as static drift test, circular motion test with drift and dynamic test were performed with and without a towed trawl to obtain the hydrodynamic forces. The influence of drift angle, yaw rate and acceleration is also considered. The towed trawl significantly affects the ship's hydrodynamic forces, particularly in the large drift angle and large yaw rate. It created an additional drag in water and it made the ship's hydrodynamic forces increase. The hydrodynamic coefficients were calculated due to the influence of the towed trawl. The results provide insights into optimizing fishing operations by improving vessel performance and efficiency under trawling conditions through changes in hydrodynamic forces due to the towed trawl.

A Study of Maneuverability Prediction of Air Cushion Vehicles Using Virtual Captive Model Test Results

Thi Thanh Diep Nguyen,Thi Loan Mai,Hoang Thien Vu,윤현규,박종열 한국항해항만학회 2024 한국항해항만학회지 Vol.48 No.5

The maneuverability of an Air Cushion Vehicle (ACV) is a critical aspect of its performance, affecting its stability, control, and overall operational effectiveness. Despite the operational complexity due to the interaction of aerodynamic and hydrodynamic forces, significant strides have been made in predicting its maneuverability. This paper discusses the maneuverability prediction of ACV based on virtual captive model tests. Hydrodynamic and aerodynamic forces on ACV's were assessed through computational fluid dynamics (CFD) calculations. Subsequently, a maneuvering simulation considering these forces was performed. The paper explores the results of aerodynamic and hydrodynamic forces during static tests such as static drift and circular motion tests. Additionally, the maneuverability performance in turning and zig-zag tests was evaluated. Furthermore, these performances were compared with the maneuvering standards suggested by the International Maritime Organization (IMO). The outcomes from the virtual captive model tests have significantly enhanced the predictive accuracy of ACV maneuverability, contributing to refined design and operational strategies.

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.

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 한국해양공학회지 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.

Effect of a Trawl Net on Hydrodynamic Forces Acting on a Fishing Vessel

Thi Thanh Diep Nguyen,Hoang Thien Vu,윤현규 한국항해항만학회 2025 한국항해항만학회지 Vol.49 No.3

Fishing vessels experience significant hydrodynamic changes when towing a trawl net, which can impact their stability, maneuverability, and fuel efficiency. Understanding these effects is crucial for enhancing vessel performance and ensuring safe and efficient fishing operations. This study explored effects of a trawl net on hydrodynamic forces exerted on a fishing vessel. The interaction between the vessel and the trawl net introduces additional resistance, affects maneuverability, and alters the overall dynamic behavior of the system. To analyze these effects, a model test was conducted to predict hydrodynamic forces acting on the fishing vessel when a trawl net was towed behind the model ship. An Arctic krill trawler was selected as the target for this study. A series of captive model tests, including static drift tests, circular motion tests with drift, and dynamic tests were carried out with or without the towed trawl net to determine hydrodynamic forces. Consideration was also given to effects of drift angle, yaw rate, and acceleration. The trawl net significantly impacted the ship's hydrodynamic forces, especially at large drift angles and high yaw rates, creating additional drag in the water and increasing the ship's hydrodynamic forces. Hydrodynamic coefficients were estimated in relation to the effect of the trawl net. These results provide insights into the optimization of fishing operations by improving vessel performance and efficiency under towing conditions through modifications in hydrodynamic forces induced by a trawl net.

Investigation of Seakeeping Performance of Trawler by the Influence of the Principal Particulars of Ships in the Bering Sea

Nguyen Thi Thanh Diep,VU HOANG THIEN,조애리,윤현규 한국해양공학회 2024 한국해양공학회지 Vol.38 No.2

Investigating ship motion under real conditions is vital for evaluating the seakeeping performance, particularly in the design process stage. This study examined the influence of the principal particulars of a trawler on its seakeeping performance. The wave conditions in the Bering Sea are investigated using available data. The length-to-beam (L/B) and beam-to-draft (B/T) ratios of the ship are changed by 10% for the numerical simulation. The response amplitude operator (RAO) motion, root mean square (RMS) value and sensitivity analysis are calculated to evaluate the influence of the trawler dimensions on ship motions. The peak RAO motion affected the ship motions noticeably because of the resonance at the natural frequency. The L/B and B/T ratios are important geometric parameters of a ship that significantly influence its RMS motion, particularly in the case of roll and pitch. The change in the B/T ratio has a good seakeeping performance based on a comparison of the roll and pitch with the seakeeping criteria. The present results provide insights into the seakeeping performance of ships due to the influence of the principal dimensions in the design stage.

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.

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.

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 한국해양공학회지 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.