• Journal of the Korean GEO-environmental Society
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• v.17 no.10
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• pp.13-22
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• 2016

An optimized spudcan was designed for the Southwestern Sea, an area mostly comprised of sand and soft clay layers. The spudcan was designed using guidelines by SNAME, ISO, and InSafeJIP, as well as the yield surface for combined loads. The probe test method was applied to define a yield surface used in estimating spudcan stability. Numerical analyses that considered vertical, horizontal, and moment loads in Southwestern Sea resulted in a design of 8 m diameter spudcan. Additionally, the empirical equations suggested by previous studies can estimate a reasonable spudcan bearing capacity at shallow depth. Each yield surface calculated from Mohr Coulomb and Hardening soil model showed different shapes, however the yield surface also grew with increasing spudcan diameter. This yield surface is a useful reference, along with site investigation results and published guidelines, to estimate the stability of a spudcan in the Southwestern Sea.

• Transactions of the Korean Society of Automotive Engineers
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• v.24 no.2
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• pp.137-143
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• 2016

The fifth wheel coupler is a heavy automotive coupling structure which connects a tractor and a trailer used for heavy-duty trucks widely. It is subjected to various loads simultaneously such as rolling, pitching and yawing loads as well as coupling frictional and impact loadings. Most of existing couplers have been overdesigned and, therefore, it is necessary to reduce the dead weight to increase the fuel efficiency. The topology optimization was applied in order to find conceptual layout designs which could show major load paths and ribs locations, and then the size structural optimization was performed in order to determine the heights and thicknesses of coupler ribs with the predetermined various loading conditions for the development of a new slim coupler with a minimum weight and high enough strength and stiffness. As the results of the topology optimum design, an efficient new coupling structure for truck trailers was designed. The weight of the new fifth wheel coupler was reduced by 4.9 %, compared with the existing one, even though all strength requirements were satisfied. The fatigue test of the new coupler was performed with cyclic vertical loads (+78.4 to +235.2 kN) and horizontal loads (-91.2 to +91.2 kN) simultaneously at 1 Hz and the life of 2,000,000 cycles were achieved without failure.

• Biomolecules & Therapeutics
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• v.13 no.3
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• pp.165-173
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• 2005

The main aim of this study was to investigate stress related activities of ginsenosides and their action mechanism. Control group and ginsenoside supplemented groups were exposed to stress while no-stress group was not done. Animals of each group (n=$8\~10$) were orally administerd 100 mg red ginseng extract (R-G), or 10 mg ginsenosides/kg body weight once a day. Animals were given materials for 5 days without stress, and then were given supplements for 5 days with restraint and electroshock stress. Mice were given materials for 5 days for experiments on anti-fatigue effect. After loading final stress, stress-related behavioral changes of experimental animals were examined and plasma corticosterone levels were measured. R-G and ginsenoside $Rb_{1}$ supplementation partially blocked the stress effects on locomotion and elevated plus-maze test in rats and mice. They also partially blocked stress induced behavioral changes such as freezing, smelling, face-washing, rearing behavior in rats. R-G and $Rb_{1}$ decrease adrenal gland size and plasma corticosterone level, which were increased by stress in rats. R-G increased enduring time on the Rota rod, cold water and horizontal wire, but $Rb_{1}$ didn't. Effects of $Rb_{1}$ on plusmaze test were inhibited by administration of flumazenil. These results suggest that $Rb_{1}$ is the main antistress principle in ginseng and it's effect is modulated by GABAnergic nervous system.

• Journal of Korean Society of Steel Construction
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• v.10 no.4 s.37
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• pp.641-655
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• 1998

It researched several jointing-methods of frame consisting of a concrete-filled steel tubular column and H-shaped beam. These beam-to-column connections is parameters to following: columns of square shape pipe infilled with or without concrete, joints assembled two types of diaphragm, outside-type and through-type. And it is testing that cyclically lateral loadings used hydraulic ram. In testing. we'll be on purposed to estimate the hysteretic behavior, strength and stiffness, energy absorption capacity, deformation capacity and failure configuration of each specimen. It is concluded that the frame specimens with outside-type are more stable and exhibit more energy absorption capacity compared with the through-type, in column of filled with concrete.

• Journal of Korean Society of Steel Construction
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• v.24 no.1
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• pp.73-80
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• 2012

The adoption of a composite beam system is regarded as a simple but effective solution because it improves the overall stiffness, strength and stability of the structure by welding shear studs. However, welding shear studs poses problems including electric shock and weld defects. Mechanical methods have emerged as an alternative to metallurgical methods for connecting the H-beam and shear connector. Four specimens were tested in order to compare the structural behavior of the proposed composite beams with that of the classical composite beam given the condition of horizontal loading. With the original composite beam (FCB-SB specimen) using stud bolts, hysteresis loops are stable, but its strength decreased with the crashing of the concrete slab around the column. The suggested composite beams using shear connectors also yielded stable hysteresis loops. Consequently, use of the suggested composite beams instead of the original composite beam are recommended.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.9
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• pp.3599-3609
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• 2010

Recently, the construction of coastal structures and high-rise structures against the horizontal and uplift forces increases with the developing the coastal developments. Especially the application of belled tension pile as foundation type to effectively resist uplift force is increasing in coastal structures. However, research on pullout resistance of belled tension pile has been limited and not yet been fully performed. Therefore, the pullout load tests of belled tension piles in four overseas sites were performed, then the bearing capacity, characteristics on load-displacement of piles and load distribution considering skin friction were investigated in this paper. In addition, the limit pullout bearing capacity calculated by the three-dimensional finite element analysis and theoretical methods were compared with values of in-situ test.

• Journal of Navigation and Port Research
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• v.30 no.1 s.107
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• pp.105-111
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• 2006

A LMTT (Linear Motor-based Transfer Technology) is a horizontal transfer system for the yard automation This system is based on PMLSM (Permanent Magnetic Linear Synchronous Motor) that consists of stator modules on the rail and shuttle car. In this research, the kriging interpolation method using sequential sampling is utilized to find the optimum design of a mover in LMTT. The design variables are considered as the transverse, longitudinal and wheel beam's thicknesses. The objective function is set up as weight, while the constant functions are set up as the stresses generated by four loading conditions. The optimum results obtained by the suggested method are compared with those determined by the GENESIS.

• Earthquakes and Structures
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• v.10 no.5
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• pp.1143-1179
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• 2016

Offshore wind turbines are considered as a fundamental part to develop substantial, alternative energy sources. In this highly flexible structures, monopiles are usually used as support foundations. Since the monopiles are large diameter (3.5 to 7 m) deep foundations, they result in extremely stiff short monopiles where the slenderness (length to diameter) may range between 5 and 10. Consequently, their elastic deformation patterns under lateral loading differ from those of small diameter monopiles usually employed for supporting structures in offshore oil and gas industry. For this reason, design recommendations (API and DNV) are not appropriate for designing foundations for offshore wind turbine structures as they have been established on the basis of full-scale load tests on long, slender and flexible piles. Furthermore, as these facilities are very sensitive to rotations and dynamic changes in the soil-pile system, the accurate prediction of monopile head displacement and rotation constitutes a design criterion of paramount importance. In this paper, the Fourier Series Aided Finite Element Method (FSAFEM) is employed for the determination of static impedance functions of monopiles for OWT subjected to horizontal force and/or to an overturning moment, where a non-homogeneous soil profile has been considered. On the basis of an extensive parametric study, and in order to address the problem of head stiffness of short monopiles, approximate analytical formulae are obtained for lateral stiffness $K_L$, rotational stiffness $K_R$ and cross coupling stiffness $K_{LR}$ for both rough and smooth interfaces. Theses expressions which depend only on the values of the monopile slenderness $L/D_p$ rather than the relative soil/monopile rigidity $E_p/E_s$ usually found in the offshore platforms designing codes (DNV code for example) have been incorporated in the expressions of the OWT natural frequency of four wind farm sites. Excellent agreement has been found between the computed and the measured natural frequencies.

• Ocean Systems Engineering
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• v.7 no.3
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• pp.179-193
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• 2017

Dynamic response analysis of offshore triceratops with stiffened buoyant legs under impact and non-impact waves is presented. Triceratops is relatively new-generation complaint platform being explored in the recent past for its suitability in ultra-deep waters. Buoyant legs support the deck through ball joints, which partially isolate the deck by not transferring rotation from legs to the deck. Buoyant legs are interconnected using equally spaced stiffeners, inducing more integral action in dispersing the encountered wave loads. Two typical nonlinear waves under very high sea state are used to simulate impact and non-impact waves. Parameters of JONSWAP spectrum are chosen to produce waves with high vertical and horizontal asymmetries. Impact waves are simulated by steep, front asymmetric waves while non-impact waves are simulated using Stokes nonlinear irregular waves. Based on the numerical analyses presented, it is seen that the platform experiences both steady state (springing) and transient response (ringing) of high amplitudes. Response of the deck shows significant reduction in rotational degrees-of-freedom due to isolation offered by ball joints. Weak-asymmetric waves, resulting in non-impact waves cause steady state response. Beat phenomenon is noticed in almost all degrees-of-freedom but values in sway, roll and yaw are considerably low as angle of incidence is zero degrees. Impact waves cause response in higher frequencies; bursting nature of pitch response is a clear manifestation of the effect of impact waves on buoyant legs. Non-impact waves cause response similar to that of a beating phenomenon in all active degrees-of-freedom, which otherwise would not be present under normal loading. Power spectral density plots show energy content of response for a wide bandwidth of frequencies, indicating an alarming behaviour apart from being highly nonlinear. Heave, being one of the stiff degrees-of-freedom is triggered under non-impact waves, which resulted in tether tension variation under non-impact waves as well. Reduced deck response aids functional requirements of triceratops even under impact and non-impact waves. Stiffened group of buoyant legs enable a monolithic behaviour, enhancing stiffness in vertical plane.

• Journal of Navigation and Port Research
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• v.32 no.8
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• pp.629-636
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• 2008

Dual Mode Trailer(DMT) systems are significantly considered as future transportation technique particularly to eliminate complicated job process in the railroad based transportation and reduce relevant logistic cost in economic viewpoint. This paper presents survey of Dual Mode Trailer(DMT) systems in terms of technical applicability in domestic industry, technical trends, etc. We provide several DMT systems addressed until now and propose suitable framework of them to our nation.