• Journal of the Korean Society of Visualization
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• v.14 no.1
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• pp.27-32
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• 2016

The reduction of $CO_2$ emissions has been a key target in the Marine Industry since the IMO's Marine Environment Protection Committee published its findings in 2009. The representative emission index is termed as the EEDI (Energy Efficiency Design Index) for the new ships. Among various flow control techniques ever proposed, the air lubrication method is the one of most promising one in terms of practical applicability. The present study examines the basic characteristics of the flat plate test with intention of applying the air lubrication technology to the reduction of the resistance of a ship. Image analysis technique is proposed as a tool to quantify the effectiveness of the air lubrication method.

• Journal of Advanced Marine Engineering and Technology
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• v.16 no.5
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• pp.50-59
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• 1992

A critical speed analysis of a pump shaft has been investigated. Among various methods in the shaft critical speed calculation, a transfer matrix method has been examined in this research. After a brief review on the transfer matrix method, a modeling procedure for a continuous structure has been discussed. Then, a critical speed of a multistage pump shaft has been estimated up to several low modes. Throughout an analysis, parametric effects on the bearing stiffness, a degree of the modeling order, and attachmant of the impeller have been investigated. As an application example, a critical speed analysis of a verical pump which has been implemented in domestic electric power plants for cooling water circulation has been conducted in order to provide a safe operation as far as a pump vibration is concerned.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2005.11a
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• pp.210-211
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• 2005

Desuperheater is a passive device to control the temperature of steam in various plants. However, in spite of its simple structure, the accurate prediction of a desuperheater is very difficult because there are many designed factors for the design of a desuperheater. In this study, the theory of heat transfer phenomena in a desuperheater was developed and the various design factors are evaluated. As a results, we confirmed that the droplet size of 30 - 200 is best effective for the performance of a desuperheater.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2002.05a
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• pp.239-244
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• 2002

Even though, tanks are used at the many industry plants, it is very difficult to control the tank level without any overflow and shortage; moreover, cause of its complication of dynamics and nonlinearity, it's impossible to realize the accurate control using the mathematical model which can be applied to the various operation modes. However, the sliding mode controller(SMC) is known as having the robust variable structures for the nonlinear control systems with the parametric perturbations and with the sudden disturbances, but the auto-tuning of parameters was a problem. Therefore, in this paper, a Genetic Algorithm based Sliding Mode Controller (GA-SMC) for the precise control of the coupled tank level was tried. GA optimized the SMCs switching parameters easily and rapidly. The simulation results are shown that the tank level could be satisfactorily controlled with less overshoot and steady-stale error by the proposed GA-SMC.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2002.05a
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• pp.261-266
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• 2002

In this Paper, we Propose model-based tuning rules of the PID controller incorporating with genetic algorithms. Three sets of optimal PID parameters for step set-point tracking are obtained based on the first-order time delay model of plants and a genetic algorithm which minimizes performance indices(IAE, ISE and ITAE). Then tuning rules are obtained using the tuned parameter sets, potential rule models and a genetic algorithm. Simulation is carried out to verify the effectiveness of the proposed rules.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2002.05a
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• pp.35-39
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• 2002

The flow characteristics in a bifurcated duct are investigated experimentally. Physical properties such as mean velocity vectors, mean vorticity and total pressure distributions are obtained for three different Reynolds numbers(578, 620, 688) using PIV measurements and CFD analysis. Also, dividing duct $90^{\circ}$ were selected for study. The results of this study would be useful to the engineer in designing the flow systems for heating, ventilation, air conditioning and wastewater purification plants.

• Journal of Marine Bioscience and Biotechnology
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• v.7 no.2
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• pp.71-78
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• 2015

Sulfated polysaccharides from plants or seaweed are well known for antioxidant, anticoagulant activity or other biological activities. The aim of the present study is to optimize the condition for the isolation of water soluble polysaccharides (WSP) and evaluate the biological activity. WSP was isolated from defatted microalgae B. braunii using chlorosulfonic acid or sulfuric acid. Among WSP isolated using sulfuric acid showed the lowest the content of total carbohydrates (g/L), whereas showed the highest antioxidant activity. Also the preliminary structural analysis of WSP was performed by FT-IR spectroscopy analysis.

• Journal of Fisheries and Marine Sciences Education
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• v.29 no.1
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• pp.51-63
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• 2017

Rice Fields have provided large areas of open water for centuries in regions with a variety of rice-growing cultures, and, in addition to producing rice also provide other animal and/or plant food sources and medicinal plants, thus acting as wetland systems and helping to sustain livelihoods and human well-being in these regions. Also rice fields in many parts of the world support important wetland biodiversity, such as reptiles, amphibians, fish, crustacean, insects and mollusca, and play a significant ole in water-bird flyways and the conservation of water-bird populations. The purpose of this study is to find a way conservation of rice fields in connection with paddies's laws, for example, amend the Conservation of Wetlands Law or legislate for the conservation of paddies.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2000.11a
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• pp.152-156
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• 2000

Many industrial equipments use RS-232C interface. But Ethernet using CSMA/CD was widly spread recently. This interface is not compatible with RS-232C and requires PC based system. So In this Paper, We decribe a Internet control and monitoring system that control and watch plants without PC. We developed IP controller consisted of microprocessor and NIC and monitoring system using VC++ and SQL database. The protocol used this system is UDP/IP because it is applicable for real time system.

• Journal of Advanced Marine Engineering and Technology
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• v.24 no.6
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• pp.128-139
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• 2000

Environmental concerns and shortage of petroleum have promoted considerable interest in the use of alternate fuels in stationary diesel engine. In this study, a heavy-duty, intercooler-turbocharged 6-cylinder stationary diesel engine was converted into stationary gas engine fueled with propane or natural gas for the cogeneration plants. One of the most important factors in the combustion features of a stationary gas engine is the fuel composition and operating parameters in terms of compression ratio, spark advance, and engine loads. Experiments with different fuel gas and load conditions were carried out with combustion pressure analysis and NOx measurement. Combustion analysis based on P-$\theta$ diagrams was also investigated by means of combustion duration and cycle variation. Compression ratio is 10.0 and ignition timing is set by using the gasoline setting as a base line and advanced toward BTDC. The results show that fuel composition and spark advance have dominant effects on combustion and NOx characteristics at operating conditions.