• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.53 no.4
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• pp.446-455
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• 2017

The improvement of resistance performance for the 4.99 ton class fishing boats was shown. The 4.99 ton fishing boats are the most commonly used one in the Korean coastal region. The evaluation of resistance performance was estimated by the Computational Fluid Dynamics (CFD) analysis. The CFD simulation was performed by the validation for various types of bow shapes on the hull. The optimized hull form from the simulation was selected and showed the best resistance performance. This hull type was tested on the towing tank in the National Institute of Fisheries Science (NIFS). The effective horsepower (EHP) was estimated by the resistance test on the towing tank with the bare hull condition. The drag force on the three service speed conditions was obtained for the resistance analysis to power prediction. The measured drag forces are compared with the results from the CFD simulation with one another. As results of the model tests, it was confirmed that the shape of the bow is an important factor in the resistance performance. The effective horsepower decreased about 30% in comparison with the conventional hull form. Also, the resistance performance improved the reduction of required horsepower, which especially contributed to the energy-saving for the fisheries industry. In the CFD analysis, the resistance performance improved slightly. In this case, the ratio of the residual resistance ($C_R$) in the total resistance ($C_T$) was high. Therefore, the CFD analysis was not enough to satisfy with reflection for the free surface and wave form in the CFD procedure. Both model test and CFD calculation in this study can be applied to the initial design process for the coastal fishing vessel.

• Korean Journal of Construction Engineering and Management
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• v.13 no.2
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• pp.58-69
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• 2012

In modern society, rooftops and underground spaces are utilized for overcoming a confined space limitation of metropolitan areas. Therefore, floor covering construction is also increasing steadily. From the user's viewpoint, skid resistance performance of floor covering methods is a very important performance criterion for safety and amenity, but an appropriate design and assessment criteria for skid resistance performance are not available. This study presents the skid resistance performance assessment method of floor covering methods considering the sidewalk skid resistance standard of Seoul city and the guideline of the Ministry of Land, Transport and Maritime Affairs(MLTM) of Korea for road safety facilities'installation and maintenance. For this research, three alternatives among urethane floor covering methods are selected and their skid resistance performance is analyzed through an experimental study. The analyzed performance is also evaluated by the skid resistance performance assessment method. Finally, the comprehensive performance assessment including the results of skid resistance performance assessment is conducted by Value Analysis(VA) in order to encourage the construction methods of floor covering which have a high skid resistance performance. As a result of VA, the particle method which the skid resistance performance is improved up to four times more than other alternatives shows the highest performance index of 83.86.

• Journal of Korean Society of Steel Construction
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• v.21 no.1
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• pp.27-35
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• 2009

Main structural steel members need fire-resistance measures to ensure their fire-resistance performance for a prescribed time. This paper analyzes and evaluates the fire-resistance performance of approved Korean fire-protection products for steel columns. These products are classified into products for board protection and for spray protection, samples of which were selected for the analysis. The fire-resistance performance was analyzed on the basis of Korean and European standards. The Korean standards are considered additional to the Euro-code standards for performance design. The Korean standards generally take more precautions to ensure safety on the temperature side, but require the reflection of material properties, the steel temperature calculation methodology, the profile factor, and the strength verification in a fire.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2011.05a
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• pp.7-10
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• 2011

In this study, evaluation system of impact resistance performance is proposed. Compressive strength of concrete is 40, 60 and 80MPa. It evaluate impact resistance performance to use projectile 6, 7 and 8mm size. As a result, safety performance is more higher when the compressive strength is increased in. Compared with Hughes's formula, evaluation system of impact resistance performance is appropriated.

• Journal of Navigation and Port Research
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• v.37 no.1
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• pp.63-69
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• 2013

Since most merchant vessels are mainly influenced by the added resistance in an actual sea, they could be navigated more efficiently if this added resistance could be precisely predicted and then effectively reduced. In this paper, we have computed the effective horsepower based on the resistance performance in still water and then calculated the added resistance in regular wave in order to estimate a ship's propulsion performance on a voyage. Firstly, we have performed experiments using a model of KCS in a circulating water channel to estimate the flow characteristics around a container ship and the ship's resistance in still water. Then we have calculated the motion response function in regular wave as well as the values for the increase in resistance, and evaluated the ship's motion performance in waves according to the calculated response function. It was found that the resistance in waves increased because the ship's motion response value became larger as the ship's speed increased in the case of head sea. The effect of the added resistance could be reduced by maneuvering the ship to the encounter angle of $120^{\circ}$ in areas of long wavelengths and to head sea in areas of short wavelengths.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.41 no.3
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• pp.222-226
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• 2005

A series of model tests carried out at the CWC of WJFEL for the purpose of prediction of resistance for the performance and improvement of resistance by attaching appendage for the ship of 50 knots class planing hull. The resistance performance evaluation has been carried out for the bare hull and for the appendage hull with two different depth of vertical type wedges. In the bare model test, trim and sinkage is calculated for the planing hull and the resistance is calculated. For minimizing the resistance, wedge appendage is attached and tested. Analysis and tests shows that for a 12.5mm wedge, resistance is minimum and overall power tallied to 5636ps.

• International Journal of Concrete Structures and Materials
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• v.11 no.2
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• pp.315-325
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• 2017

The purpose of the paper is to determine the influence of two widely used steel fibers and polypropylene fibers on the sulphate crystallization resistance, freeze-thaw resistance and surface wettability of ultra-high performance concrete (UHPC). Tests were carried out on cubes and cylinders of plain UHPC and fiber reinforced UHPC with varying contents ranging from 0.25 to 1% steel fibers and/or polypropylene fibers. Extensive data from the salt resistance test, frost resistance test, dynamic modulus of elasticity test before and after freezing-thawing, as well as the contact angle test were recorded and analyzed. Fiber hybridization relatively increased the resistance to salt crystallization and freeze-thaw resistance of UHPC in comparison with a single type of fiber in UHPC at the same fiber volume fraction. The experimental results indicate that hybrid fibers can significantly improve the adhesion properties and reduce the wettability of the UHPC surface.

• Fire Science and Engineering
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• v.23 no.5
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• pp.78-83
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• 2009

17 kinds of fire resistant paint which are currently used were painted on the MDF, to find flame resistance performance and smoking characteristics according to principal ingredient and characteristics of fire resistant paint. 45 degree combustion test and smoke density test were conducted to investigate the flame resistance performance and smoking characteristics. According to the 45 degree combustion test, acrylic resin type fire resistant paint showed the most excellent fire resistance performance. And the water soluble fire resistant paint showed better fire resistance performance compare to the solvent soluble paints. Also gloss paint showed better fire resistance performance than the flat paint. Based on the smoke density test, the smoke generation of fire resistant treated specimen of acrylic resin type was least. And the water soluble fire resistant paint generate little smoke than solvent soluble fire resistant paint.

• Journal of Korean Association for Spatial Structures
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• v.17 no.2
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• pp.33-41
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• 2017

Composite Floor system infilled with PCM(Phase Change Material) between upper and lower steel plates was developed to apply the steel frame. When steel frames were applied this system, it can absolutely reduce the duration of construction due to dry construction method. However to apply this system as a structural floor member without fire resistance covering, it must have 2 hours fire resistance performance. Because PCM consisted of three quarters of section with thermal insulation performance, fire resistance performance of this floor system was expected to easily have 2 hours fire resistance performance. This paper was to investigate behavior characteristics of PCM infilled floor system at elevated temperature using FEM analysis to develop the fire resistance performance of it.

• Journal of the Society of Naval Architects of Korea
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• v.59 no.6
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• pp.393-399
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• 2022

During the ship hull design process, resistance performance estimation is generally calculated by simulation using computational fluid dynamics. Since such hull resistance performance simulation requires a lot of time and computation resources, the time taken for simulation is reduced by CPU clusters having more than tens of cores in order to complete the hull design within the required deadline of the ship owner. In this paper, we propose a method for estimating resistance performance of ship hull by simulation using a graph neural network. This method converts the 3D geometric information of the hull mesh and the physical quantity of the surface into a mathematical graph, and is implemented as a deep learning model that predicts the future simulation state from the input state. The method proposed in the resistance performance experiment of simple hull showed an average error of about 3.5 % throughout the simulation.