Optimal design method of bulbous bow for fishing vessels

Tran Thai Gia,Van Huynh Chinh,Kim Hyun Cheol 대한조선학회 2021 International Journal of Naval Architecture and Oc Vol.13 No.1

Although widely used, the design of the bulbous bow for ships has been difficult due to the complex interference between the wave system generated by the bulb and the wave system of the ship hull. Until now, a bulbous bow has been often designed using Kracht charts, which were established based on model test data, but these charts apply only to ships with a block coefficient CB ¼ 0.56-0.82, Froude number Fn ¼ 0.20-0.40, and the obtained bulb sizes are only close to optimal. This paper presents a new method for the optimal design of bulbous bow, starting from the design of an initial bulb using Kracht charts for ships with any block coefficient or Froude number, then resizing this initial bulb to define the optimal bulb sizes based on a multi-objective function of the required power reduction, and a combined solution of Computation Fluid Dynamics (CFD) analysis and surrogate models. This study was applied to a fishing vessel FAO 75, which has been model tested and used to design steel fishing vessels in Vietnam recently. The obtained quantitative results showed the same trend as the theory and practice, with a reduction of the ship’s required power by about 14%.

Optimization strategy for planing hull design

Tran Thai Gia,Van Huynh Quang,김현철 대한조선학회 2022 International Journal of Naval Architecture and Oc Vol.14 No.1

The planing hull optimization has always been a difficult problem due to the trim changes caused by lift force and complex hydrodynamic interactions at high speeds. In this paper, a strategy is presented to optimize a planing hull design, starting from using dimensional analysis to establish a resistance objective function depending on three dimensionless hull form parameters, then using CFD or Savitsky method to predict resistance for each hull variant formed by changing each pair of hull form parameters in the resistance objective function, and finally, determining an optimal hull formvariant with minimum resistance based on the combination of the Kriging surrogate model and Neldel-Mead optimization algorithm. In addition, our modified Savitsky computational procedure and suitable inputs for the CFD solver are also applied to improve the accuracy of planing hull resistance predictions. For practicality, the proposed strategy was applied to evaluate the design of a high-speed vessel, named K88, which was model tested but did not achieve the expected performance. As a result, this vessel can be optimally redesigned with the ability to reduce total resistance by about 11.3% when simultaneously correcting deadrise angle and breadth, and by about 19.4% when simultaneously correcting deadrise angle and chine height at the bow.

A study on the matching problem of engine, propeller, and ship hull under actual service conditions

Tran Thai Gia,김현철 대한조선학회 2023 International Journal of Naval Architecture and Oc Vol.15 No.-

In ship design, the matching of engine, propeller, and hull is an analytical process to establish the optimal operating mode so that the engine works safely with full power and the lowest fuel consumption, and a ship reaches desired speed. In theory, the operating process of the engine, hull, and propeller is usually expressed by their characteristics, and the matching problem is solved by finding the intersection of these characteristics. The problem here is that the above characteristics are determined under design conditions, corresponding to the standard technical conditions of the engine, hull, and propeller, however, all of these will be changed under actual service conditions, leading to a change in the position of the defined design match points and thereby greatly affect the safety and performance of the ships. This paper presents a new approach to determining the actual characteristics of the engine, hull, and propeller and how to use them to solve the matching problem under service conditions. This study was verified and validated on three study ships and was also applied to solve the matching problem of the Glory Star tanker. All the obtained results are in good agreement with the published real experimental data for this ship with a power loss of 21.5% under current service conditions, including 6.5% due to changes in propeller characteristics by changing technical conditions of propeller and hull surface, 6.3% due to engine deterioration, and 8.7% due to the engine - propeller mismatch after 5 years of operation.

Facile synthesis of multifunctional Ag/Fe3O4-CS nanocomposites for antibacterial and hyperthermic applications

Ngoan Thi Nguyen,Dai Lam Tran,Duc Cuong Nguyen,Thai Loc Nguyen,Thi Cham Ba,Binh Hai Nguyen,Thi Duong Ba,Nam Hong Pham,Dzung Tuan Nguyen,Thai Hoa Tran,Gia Dien Pham 한국물리학회 2015 Current Applied Physics Vol.15 No.11

Nanocomposites containing two or more functional constituents are attractive candidates for advanced nanomaterials. In this study, multifunctional Ag/Fe3O4-CS nanocomposites were successfully prepared, using chitosan as a stabilizing and cross-linking agent. The as-synthesized nanocomposites were characterized by Transmission Electron Microscopy (TEM), Scanning Electron Microscopy (SEM), X-ray diffraction (XRD), Energy-dispersive X-ray spectroscopy (EDS), UVevisible spectrophotometer (UVeVis) and vibrating sample magnetometer (VSM). The results demonstrated that Ag/Fe3O4-CS composite nanoparticles (NPs) were composed of parent components, Fe3O4 and Ag NPs, which were uniformly dispersed in the chitosan matrix. The hybrid NPs exhibited strong antibacterial property against Pseudomonas aeruginosa. With high magnetization value (67 emu/g), the synthesized Ag/Fe3O4-CS composite can be easily separated or recycled in potential biomedical applications. Furthermore, the results showed that the multicomponent hybrid nanostructures appeared to be the promising material for local hyperthermia, which can be used as thermoseeds for localized hyperthermia treatment of cancers.

The Impact of Country of Origin on Consumption Intention: A Case Study of COVID-19 Vaccines in Vietnam

Minh Sang VO,Ngoc Phu TRAN,Thi Kieu Thu NGUYEN,Thi Cam Tien HUYNH,Thi Kim Loi NGUYEN,Le Phuong Nghi THACH,Gia Nhu THAI,Thi Thanh Sang TRAN 한국유통과학회 2022 The Journal of Asian Finance, Economics and Busine Vol.9 No.4

This study intends to analyze the impact of the country of origin on the intention to ingest COVID-19 vaccinations by measuring Vietnamese people’s perceptions of India in the manufacture of COVID-19 vaccines. The research is done using a quantitative method, and primary data was obtained using a conventional manner based on the willingness of the research respondents, who are Vietnamese persons aged 18 and up, to contribute information. The findings revealed that perceived brand association and perceived brand quality directly positively impact the COVID-19 vaccine’s consumption intention and willingness. Meanwhile, while the perceived country image component has no direct effect on consumption intention, it does have a positive indirect effect on consumption intention through perceived brand linkage and perceived brand quality. The findings also emphasize the importance and significance of a country’s image in brand association and quality perception. The study’s findings imply that to increase consumers’ willingness to buy India’s COVID-19 vaccination, the country should develop communication initiatives to improve consumer perceptions of the country’s image, the perceived value of the brand association, and brand quality.

Biomedical and Environmental Applications of Chitosan-based Nanomaterials

( Jae Kweon Park ),( Lam Dai Tran ),( Hoang Vinh Tran ),( Trang Thu Mai ),( Thu Phuong Ha ),( Binh Hai Nguyen ),( Hoang Thai ),( Hoang Dinh Vu ),( Dien Gia Pham ),( Phuc Xuan Nguyen ) 한국키틴키토산학회 2011 한국키틴키토산학회지 Vol.16 No.1

Being naturally abundant resources and having many interesting physicochemical and biological properties, chitin/chitosan have been found useful in many fields. This paper describes the strategy to design a multifunctional, chitosan based nanomaterials and their biomedical and environmental applications. Different physicochemical methods including FESEM/TEM, PPMS were used to characterize the obtained nanomaterials. For each application, a series of specific characterizing methods were used for evaluating the applicability/capacity of materials.

Consumer Perceptions and Consumer Behavior Toward Bio-Based Products: An Empirical Study in Vietnam

Trong Luan NGUYEN,Ngoc Phu TRAN,Thi Kieu Thu NGUYEN,Thi Cam Tien HUYNH,Thi Kim Loi NGUYEN,Le Phuong Nghi THACH,Gia Nhu THAI,Thi Thanh Sang TRAN 한국유통과학회 2021 The Journal of Asian Finance, Economics and Busine Vol.8 No.12

Green economy, also known as sustainable economy, is a current development trend in which consumers prefer products that are wholly or partly derived from materials of biological origin since they have become more concerned about their health and the environment in which they live. This study aims to examine consumer behavior toward bio-based products with three key goals in mind. First, it helps to understand the perception of consumers toward Bio-based products. Second, it properly helps consumers be aware of products derived from materials of biological origin so that the consumer can make purchasing decisions to protect their health and contribute to the protection of the environment. Third, the study on consumer behavior towards bio-based products will provide a more accurate view and assessment to companies looking to develop Bio-based products. Based on that, the research is carried out through surveying, collecting data from consumers, and then using the deductive approach, descriptive statistics, and quantitative method analysis. The results demonstrated that a positive relationship and a direct impact are established between the variables of Attitude and Social Norms and the Purchase Intention toward Bio-based products. Furthermore, the findings reveal that customers have positive feelings towards bio-based products in terms of trust, knowledge, and the environment.