• Nuclear Engineering and Technology
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• v.48 no.1
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• pp.64-71
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• 2016

Void fraction is an important parameter in the oil industry. This quantity is necessary for volume rate measurement in multiphase flows. In this study, the void fraction percentage was estimated precisely, independent of the flow regime in gas-liquid two-phase flows by using ${\gamma}-ray$ attenuation and a multilayer perceptron neural network. In all previous studies that implemented a multibeam ${\gamma}-ray$ attenuation technique to determine void fraction independent of the flow regime in two-phase flows, three or more detectors were used while in this study just two NaI detectors were used. Using fewer detectors is of advantage in industrial nuclear gauges because of reduced expense and improved simplicity. In this work, an artificial neural network is also implemented to predict the void fraction percentage independent of the flow regime. To do this, a multilayer perceptron neural network is used for developing the artificial neural network model in MATLAB. The required data for training and testing the network in three different regimes (annular, stratified, and bubbly) were obtained using an experimental setup. Using the technique developed in this work, void fraction percentages were predicted with mean relative error of <1.4%.

• Journal of Fisheries and Marine Sciences Education
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• v.21 no.3
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• pp.373-389
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• 2009

The aims of this study are to examine urgent problems for reorganization into future-proof large purse seine fisheries in order to positively cope with rapidly changing domestic and foreign fisheries circumstances. First, this paper provides current situations of the large purse seine fisheries. The current situations of it are composed of fisheries influence such as vessel number, vessel power, and fisher number, use of resource and fishing places, and changes in products and sales of species caught by the large purse seine. Secondly, this paper reviews current problems of the large purse seine fisheries including cost reduction and increase of value added. Thirdly, this paper suggests basic development direction and countermeasures for strengthening competitiveness of the large purse seine fisheries. In conclusion, urgent problems of the larger purse seine fisheries can be summarized as inefficiency of distribution structures and retarded landing system and facilities as well as the worse of profitability according to shrink of fishing places, reduction of products, lack of workers, and increase in oil price. To solve the urgent problems, the large purse seine fisheries should be changed into an industry with low cost and high efficiency, and also need to introduce of new production system, strengthen autonomous management of natural resource, and increase in value added to products.

• Bulletin of the Korea Photovoltaic Society
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• v.3 no.2
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• pp.48-54
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• 2017

Nowadays Viet Nam's energy supply which is mainly produced by fossil fuels energy such as coal, gas, and oil. However, the operation of fossil fuel power plants is one of the major causes of environmental pollution and climate change as well. It has a serious impact on the survival of human beings in general. As can be seen, the manufacturing industry is strongly invested, the demand for energy is also increasing. As traditional fossil fuels are being depleted and to minimize environmental pollution, renewable energy is the solution widely used by many countries in the world. Therefore, renewable energy has a significant role in maintaining the sustainability of world economy. Renewable energy sources such as solar energy, wind energy, biomass energy, geothermal energy can supply clean and nature-sourced energy to replace fossil fuels. Encouraging development of renewables is a general trend in the world today, which is also a common goal of COP21 commitment on global GHG reduction. The objective of this study is to assess the opportunities and challenges for renewable energy development in Vietnam, particularly for solar power. This study also discusses policies to promote the development of solar energy in Vietnam. While solar power provides ecological, economic and social benefits, it is exploited very modestly in Vietnam, where there are many barriers to slow down the development of renewable energy.

• Journal of Energy Engineering
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• v.23 no.2
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• pp.57-61
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• 2014

Challenges the automotive industry as the increase in consumption of oil and energy, $CO_2$ emissions of global warming, caused by exhaust emissions and urban air pollution, it is time for a deal is needed. The solution of these highly regarded in the market as there is a demand of electric cars. In this study, electric car motor, battery and high-voltage core components, including the drive motor of the effective thermal management technologies, thermal management of the battery and the drive motor to evaluate the technology and development trends.

• Journal of the Korean Society for Precision Engineering
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• v.30 no.10
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• pp.1041-1049
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• 2013

One of the causes of malfunction of commercial vehicle is corrosion or wear. In order to prevent corrosion and wear, lubricants have to be supplied periodically. However, the period of lubrication usually depends on operator's judgment. If the period is too short, excess lubricant will cause pollution and unnecessary expenses, where as long periodic supply of lubricant might cause wear, damage and eventual breakdown. Therefore, an automatic lubrication system with predetermined interval will reduce the excessive supply of lubricating oil and prevent wear and damage. This thesis presents an automatic lubrication system which consists of a lubricant pump and an embedded controller. An automatic lubrication operating algorithm is used to operate the lubricant pump and feedback the pressure status of the system using pressure sensors. The developed system shows an efficient periodic supply of lubricant.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.18 no.9
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• pp.64-71
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• 2019

We herein propose a systematic design method of hydraulic pipes used in heavy construction equipment. We found that even though many design studies have been conducted regarding major hydraulic components such as pumps, cylinders, and control valves, studies regarding the optimal design of hydraulic pipes are scarce. In this study, the design of four types of pipes is considered: two high-pressure and two low-pressure pipes. First, fluid flow analysis was conducted based on oil flow and pressure for various radii of curvature. For a check-valve pipe, we considered the location of an inlet pipe. We could visualize fluid flow inside the pipe according to the flow velocity and pressure distribution. Based on fluid flow analysis, we conducted a structural analysis that revealed the stress distribution and concentration for each pipe design. We selected the best design parameters for each pipe design, fabricated the pipes, and subsequently tested them for validity.

• International Journal of Naval Architecture and Ocean Engineering
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• v.7 no.3
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• pp.435-451
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• 2015

Evaluation of the performance of aging structures is essential in the oil and gas industry, where the inaccurate prediction of structural performance can have significantly hazardous consequences. The effects of structure failure due to the significant reduction in wall thickness, which determines the burst strength, make it very complicated for pipeline operators to maintain pipeline serviceability. In other words, the serviceability of gas pipelines and elbows needs to be predicted and assessed to ensure that the burst or collapse strength capacities of the structures remain less than the maximum allowable operation pressure. In this study, several positions of the corrosion in a subsea elbow made of API X42 steel were evaluated using both design formulas and numerical analysis. The most hazardous corrosion position of the aging elbow was then determined to assess its serviceability. The results of this study are applicable to the operational and elbow serviceability needs of subsea pipelines and can help predict more accurate replacement or repair times.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.20 no.10
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• pp.95-101
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• 2021

An analysis was conducted to predict the behavior of gasket by applying an optimal-strain energy-density function selected through a uniaxial tensile test and an analysis of the gasket used in an actual hydrogen fuel cell. Among the models compared to predict the materials' properties, the Mooney-Rivlin secondary model showed the behavior most similar to the test results. The maximum stress of the gasket was not significantly different, depending on the location. The maximum surface pressure of the gasket was higher at positions "T" and "Y" than at other positions, owing to the branch-shape effect. In the future, a jig that can measure the surface pressure will be manufactured and a comparative verification study will be conducted between the test results and the analysis results.

• Korean Journal of Veterinary Service
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• v.41 no.4
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• pp.251-255
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• 2018

Bordetella bronchiseptica and Pasteurella multocida are two main pathogens responsible for atrophic rhinitis (AR), which causes considerable economic losses in swine industry worldwide. Commercial vaccine has been widely used to prevent the damage from AR in Korea. Adverse effects of vaccination at the injection site have been reported, which results in the numerous complaint from farms. However, data on about local reaction at the injection site remains limited. In this study, we compared the local adverse effects of three commercial vaccines following intramuscular injection. The results showed that no gross lesion was founded at the injection sites of all three vaccines. In histopathologic examination, a various level of lesions was identified. Especially, the local reaction of vaccine including saponin as an adjuvant showed the lowest level of histopathological lesions, when compared to those of oil-based and vitamin E-based vaccines. Therefore, this study would provide the information about the extent of local reaction at the injection site and help the farmer to select AR vaccine in order to avoid adverse reaction due to vaccination.

• Journal of Ocean Engineering and Technology
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• v.33 no.4
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• pp.330-339
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• 2019

Radiant heat shields are normally installed on offshore oil and gas platforms to protect personnel, equipment, and structures from the thermal radiation emitted by a flare system. A heat shield should be individually designed to reduce the thermal radiation to the target level, and then manufactured and installed after the performance verification. However, in general, a heat shield is designed and manufactured by trial and error based on the performance test. For this reason, it is difficult to develop and design radiant heat shields in the Korean shipbuilding and marine equipment industry because of the lack of performance test data and limited experience. In the present study, the results of experiments conducted to verify the performances of radiant heat shields were analyzed, and the thermal radiation characteristics and performance characteristics of the radiant heat shields were investigated. The insights and conclusions developed in the present study will be useful in terms of the design and development of radiant heat shield, as well as in their performance verification tests.