• Journal of Korean Society of Coastal and Ocean Engineers
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• v.2 no.1
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• pp.43-50
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• 1990

This study is concerned with the optimization of steel jacket subjected to wave forces using the allowable stress design method. The optimization of member section is considered here. Objective function for the minmum cost design is obtained by considering the weight of steel jecket. Constraints are imposed to insure that structural displacement and strength are within allowable values. The nonliner otimization problems are solved by SUMT method including the modified Newton-Raphson method.

• Journal of the Korean Society for Precision Engineering
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• v.14 no.2
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• pp.33-40
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• 1997

Recently, there are an increasing needs for high speed rotating spindle which is an important mechanical ele- ment for a high efficiency machine tool in order to shorten machining time and cut production costs. The heat gen- eration is the most important problem in the motor integrated spindle. In this study, the effects of temperature distribution and thermal behavior according to the oil-air lubrication and cooling conditions are investigate theo- retically and experimentally on the motor-integrated spindle under unloading condition. The experimental spin- dle system is composed with the angular contact steel ball bearings, oil-air lubrication, air or oil jacket cooling system. To analyze the thermal behavior and cooling characteristics for the motor integrated spindle, the analysis using the finite element method is carried out. The analytical results are compared with the experimental results.

• Journal of KIBIM
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• v.12 no.1
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• pp.62-71
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• 2022

In order to overcome the limitations of th 2D method regardless of the client's request, the application of BIM was reviewed to create hight-quality products using 3D models and various BIM information for offshore wind jacket-type structures. First, we defined the input value through analysis of the target structure and wrote an algorithm(script library) and library to complete the BIM model. Design review using geometry information based on th BIM model, usage for visualization drawings and quantity calculation were reviewed. For the purpose of initial review, only libraries with a limited number of subjects limitations on the scope of research were used. However, in the futrue, various libraries will be developed and research will be conducted to expand the scope of subjects.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.34 no.1
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• pp.87-94
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• 2014

This study analyzes the characteristics of bond behavior of concrete, which is confined by external jackets such as shape memory alloy (SMA) and steel, according to confinement and stiffness ratios of the external jackets. For this purpose, SMA wires with 1.0 mm diameter and steel plates with 1.0 and 1.5 thickness are used to induce difference on confinement and stiffness ratios and, then, bond strength and behavior are analyzed considering the two factors. When external jakcets are used for the concrete cylinders, bond strengths of specimens increase and their bond failures are transferred from splitting failure to pull-out failure and, thus, the external jackets show confining effect. Bond strenght of concrete increase with increasing confinement and stiffness ratios of the external jackets. However, maximal circumferential strains decrease linearly with increasing the two values.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.17 no.4
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• pp.83-93
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• 2017

In everyday life, the ratio of credit card aspect ratio is 1: 1.56, and A4 printer paper is 1: 1.414, which is relatively balanced golden ratio. In this paper, we show the Fibonacci Golden ratio as a polynomial based on the golden ratio, which is the most balanced and ideal visible ratio, and show that the application of Euler and symmetric jacket polynomial is related to BPSK and QPSK constellation. As a proof method, we have derived Fibonacci Golden and Galois field element polynomials. Then mathematically, We have newly derived a golden jacket code that can be used to generate an appropriate code with orthogonal properties and can simply be used for inverse calculation. We also obtained a channel capacity according to the channel correlation change using a block jacket matrix in a MIMO mobile communication.

• Journal of the Korea Convergence Society
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• v.12 no.2
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• pp.185-191
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• 2021

The characteristics of the foundry sand were analyzed for water jacket core required to prevent structural deformation from the heat generated in the cylinder bore during the casting of the cylinder block of an automobile. The sand core tensile strength tester, AFS-GFN, and optical microscope were used to evaluate the its properties. If the SiO2 content is high in the foundry sand, the dimensional defects and veining defects occur due to high temperature expansion. Also, if it is too low, the core breakage, porosities, chemical burn-on defects occur. The particle size index and grain shape influenced the core strength and resin consumption, resulting in fluctuations in defect types. The higher the alkalinity of the dried sand, the lower the core strength. And the more basic, the lower the core strength. At the resin content of 1.6~1.8%, the increase in core strength after 1 hour curing was approximately at its maximum.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.35 no.2
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• pp.93-100
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• 2022

The collision behaviors of the tripod and jacket structures, which are considered as support structures for offshore wind towers at the Southwest sea of Korea, were compared by nonlinear dynamic analysis. These structures, designed for the 3 MW capacity of the wind towers, were modeled using shell elements with nonlinear behaviors, and the tower structure including the nacelle, was modeled by beam and mass elements with elastic materials. The mass of the tripod structure was approximately 1.66 times that of the jacket structure. A barge and commercial ship were modeled as the collision vessel. To consider the tidal conditions in the region, the collision levels were varied from -3.5 m to 3.5 m of the mean sea level. In addition, the collision behaviors were evaluated as increasing the minimum collision energy at the collision speed (=2.6 m/s) of each vessel by four times, respectively. Accordingly, the plastic energy dissipation ratios of the vessel were increased as the stiffness of collision region. The deformations in the wind tower occurred from vibration to collapse of conditions. The tripod structure demonstrated more collision resistance than the jacket structure. This is considered to be due to the concentrated centralized rigidity and amount of steel utilized.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2008.11a
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• pp.463-464
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• 2008

• Journal of Advanced Marine Engineering and Technology
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• v.40 no.4
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• pp.282-287
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• 2016

Recently in order to protect the ocean environment and to reduce energy consumption, shipbuilders have been developing highly economized ships. This research analyzed the possibility of adopting the onshore absorption refrigerator to offshore ships having a cooling system with refrigerant by using the waiste heat of the engine jacket cooling water instead of compression refrigerators. The results showed that R236fa could be a suitable medium for absorbing the heat of the absorber and condenser in an absorption refrigerator. The cooling system using R236fa achieved a high COP of 0.798, which is 15% and 5% higher than an air cooling system with a cooling tower and a water cooling system with a heat exchanger, respectively. The cooling system with R236fa achieved high efficiency with a 25% reduction in flow rate of LiBr solution and only 15.7% flow rate of cooling medium as compared to the water cooling system. The heating of sea water by the engine jacket water flowing out from the generator can prevent the crystallization of LiBr solution due to the low temperature of sea water.

• Journal of the Korea institute for structural maintenance and inspection
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• v.13 no.2 s.54
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• pp.215-222
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• 2009

In this study, steel and FRP jackets are used to confine concrete cylinders. The FRP jacket behaviors compositely with concrete since there is bonding between them. However, the used steel jacket in this study do not behavior compositely with concrete since there is not an adhesive between them. The steel jackets are attached by external forces and the welding. This study suggests the measuring method of the axial strain for the confined concrete cylinders showing noncomposite behavior with the jackets and the correcting method of the measured strain for the composite-behavior jackets. For the noncomposite-behavior steel jacket, the axial strain of the steel surface does not represent the axial strain of the concrete inside. Also, a compressormeter can not be used. Thus, the two rigid plates at the top and bottom of a cylinder are placed and the distance of the two plates are measured and used for estimating the axial strain of the concrete. For the composite-behavior FRP jacket, the vertical strain measured on the FRP surface can be used for estimating the axial strain of the concrete. However, the vertical strain on the FRP surface contains the tensile strain due to the bulge of the concrete and, thus, the tensile strain should be corrected from the vertical strain. The corrected verticals strains compared with the measured strain or a existing constitute model; the result is satisfactory. The uncorrected stress-strain curves have the potential to under estimate the ductile behavior and the energy-dissipation-capacity of the composite-behavior FRP jackets.