• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.1
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• pp.315-323
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• 2016

This study examined the durability and method for making a mockup of bobsled tracks for constructing a bobsled stadium, which is a sport in the Winter Olympics. As bobsleigh games are very fast and dangerous, a safety design for players and a precise construction using highly efficient shotcrete is necessary. Moreover, a general molding construction is difficult because bobsleigh tracks are composed of various curves and slopes, and it is necessary to construct them using high-strength and high durability materials. The developed method for making a mockup and performing durability evaluation of bobsleigh tracks through this research will be applied in the construction of the 2018 Pyeongchang Winter Olympics Sliding centre and bobsleigh tracks using domestic techniques.

• Journal of the Society of Naval Architects of Korea
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• v.57 no.1
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• pp.23-34
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• 2020

This paper covers the development of prediction techniques for ice load on ice-breakers operating in continuous ice-breaking under level ice conditions using particle-based continuum mechanics. Ice is assumed to be a linear elastic material until the fracture occurs. The maximum normal stress theory is used for the criterion of fracture. The location of the crack can be expressed using a local scalar function consisting of the gradient of the first principal stress and the corresponding eigen-vector. This expression is used to determine the relative position of particle pair to the new crack. The Hertz contact model is introduced to consider the collisions between ice fragments and the collisions between hull and ice fragments. In order to verify the developed technique, the simulation results for the three-point bending problems of ice-specimen and the continuous ice-breaking problem around a wedge-type model ship with bow angle of 20° are compared with the experimental results carrying out at Korea Research Institute of Ships and Ocean Engineering (KRISO).

• International Area Studies Review
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• v.13 no.1
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• pp.167-186
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• 2009

The purpose of this study was to estimate the economic impact of the 23 sport-events in the city of Sokcho using an input-output(I-O) model. The multipliers of the sport-events were derived with respect to output, value added, personal income, indirect tax, and employment. The survey was conducted to estimate the total expenditures from participants (players, staffs, and spectators) (N = 1,026). In results, the lifetime sport-events were much more efficient than the elite sport-events in qualitative perspectives. Consequently, the result of this study can be used as an objective indicator to help to establish sport policies for the city of Sokcho.

• Journal of the Society of Naval Architects of Korea
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• v.32 no.1
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• pp.103-117
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• 1995

A design-oriented method for analysis of the structural damage due to ship collisions is developed by using the idealized structural unit method(ISUM). The method takes into account yielding, crushing, rupture, the coupling effects between local and global failure of the structure, the influence of strain-rate sensitivity and the gap/contact conditions. The method is verified by a comparison of experimetal and numerical results obtained from test models of double-skin plated structures in collision/grounding situations with the present solutions. As an illustrative example, the method has been used for analyses of a side collision of a double-hull tanker. Several factors affecting ship collision response. namely the collision speed and the scantlings/arrangements of strength members, are discussed.

• Journal of the Society of Naval Architects of Korea
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• v.38 no.2
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• pp.33-43
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• 2001

The design and construction of special purpose vessels such as drillship and shuttle tankers have been increased. These vessels install the DPS(dynamic positioning systems) to maintain the position and heading for long-time operation. This paper deals with the experimental method for model-based DP system and the control theory and filter algorithms. In this experiment, the length of model ship is 4 meters and it has three thrusters to maintain the position. The ability of tracking along the given course and keeping of heading in waves are confirmed. For the calculation of thruster input the PID control theory are adopted and the effects of PID gain were investigated. To estimate the low frequency motions Kalman filter and digital filter were used and their effects were investigated.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.30 no.3
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• pp.209-219
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• 1994

The practical application of riblet to three dimensional double model, for viscous drag reduction, was studied analytically by intergal solution to three dimensional turbulent boundary layers. The case of a V-groove riblet technique on the shear stress and boundary layer velocities were incooperated in the computation of the flow over a smooth slender ship hull. As the results the possible mechanism of turbulent drag reduction by riblets are then suggested based on detailed studies of near-wall turbulence characteristics. And a turbulent boundary layer calculation scheme based on a momentum integral method was modified for the computer program. An example of the calculation results is presented.

• Journal of Ocean Engineering and Technology
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• v.26 no.6
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• pp.46-52
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• 2012

The motions and drift forces of side-by-side moored FSRU and LNGC including the sloshing effect, were studied using experiments. The FSRU and LNGC contained LNG cargo tanks and the LNG sloshing could affect the motions and drift forces of the structures due to its coupling with floating body motion. The effect of coupling can vary with the LNG filling level, and the effect of the filling level was investigated. The coupling effect was stronger at lower filling level. It was confirmed that longitudinal sloshing influenced the surge and surge mean drift force in head sea. In addition, gap flow affected the sway and mean drift forces. Sloshing attenuated the sway and yaw excited by gap flow in side-by-side configuration.

• Journal of Navigation and Port Research
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• v.28 no.8
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• pp.753-757
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• 2004

The free-surface flow is simulated to make clear the viscous interaction of stem waves and the sub-breaking phenomena around a high speed vehicle. The Navier-Stokes equation is solved by a finite difference method where the body-fitted coordinate system, the wall function and the triple-grid system are invoked They are applied to study precisely on the stem flow of S-103 as to which extensive experimental data are available. Computations are extended to the submerged revolutional body. The numerical result shows that the gradient of M/Us is greatly influenced by the submerged depth And the stem wave is influenced by the separation due to the bow wave.

• Journal of Ocean Engineering and Technology
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• v.23 no.4
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• pp.38-46
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• 2009

Two sets of numerical simulations were carried out for a planing hull model ship. In the first, the WAVIS 1.4 linear and nonlinear potential solver was utilized with the free support condition, in which the running posture was determined during calculation. The linear and nonlinear potential calculation results showed qualitative agreement in the trim and resistance coefficient with the MOERI towing tank test. However, the nonlinear potential calculation gave better results than the linear method. In the next simulation, Fluent 6.3.26 with a VOF model and the WAVIS 1.4 nonlinear potential solver were used with the given running posture from the measurement carried out in the MOERI towing tank. Fluent with the VOF method had substantially better agreement with model test results than the results from the WAVIS nonlinear potential calculation for the total resistance coefficient, and for the bow and stern wave patterns, in spite of the much greater computational costs. Both methods can be utilized in planing hull design when their limitations are perceived, and the running posture should be predicted correctly.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.33 no.5
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• pp.287-296
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• 2020

The wave-impact load on offshore structures can be divided into green-water and wave-slamming impact loads. These wave impact loads are known to have strong nonlinear characteristics. Although the wave impact loads are dealt with in the current classification rules in the shipping industry, their strong nonlinear characteristics are not considered in detail. Therefore, to investigate these characteristics, wave-impact loads induced by a breaking wave on a circular cylinder were analyzed. A model test was carried out to measure the wave-impact loads due to breaking waves in a two-dimensional (2D) wave tank. To generate a breaking wave, the focusing wave method was applied. A series of 2D tank tests under a horizontal wave impact was carried out to investigate the structural responses of the cylindrical structure, which were obtained from the measured model test data. According to the results, we proposed a structural damage-estimation procedure of an offshore tubular member due to a wave impact load. Furthermore, a recommended wave-impact load is suggested that considers the minimum required thickness of each member. From the experimental results, we found that the required minimum thickness is dependent on the impact pressure located in a three-dimensional space on the surface of a tubular member.