• Journal of the Society of Naval Architects of Korea
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• v.51 no.6
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• pp.503-509
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• 2014

This paper describes the time-domain numerical method for prediction of slamming loads on a ship in waves using the strip theory. The slamming loads was calculated considering the relative vertical velocity between the instantaneous ship motion and wave elevation. For applying the slamming force on a ship section, the momentum slamming theory and the empirical formula-based bottom slamming force were used corresponding to the vertical location of wetted body surface. Using the developed method, the vertical bending moments, relative vertical velocities, and impact forces of S175 containership were compared in the time series for various section locations and wave conditions.

• Journal of the Society of Naval Architects of Korea
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• v.45 no.1
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• pp.1-9
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• 2008

The free-surface motions interacting with structures are investigated numerically using the Moving Particle Semi-implicit (MPS) method proposed by Koshizuka et al. (1996) for solving incompressible flow. In the method, Lagrangian moving particles are used instead of Eulerian approach using grid system. Therefore the terms of time derivatives in Navier-Stokes equation can be directly calculated without any numerical diffusion or instabilities due to the fully Lagrangian treatment of fluid particles and topological failure never occur. The MPS method is applied to the numerical study on the fluid impact loads for wet-drop tests in a LNG tank, and the results are compared with experimental ones.

• International Journal of Naval Architecture and Ocean Engineering
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• v.4 no.2
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• pp.83-95
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• 2012

In the present study, the structural response of breakwaters installed on container carriers against green water impact loads was numerically investigated on the basis of the fluid-structure interaction analysis. A series of numerical studies is carried out to induce breakwater collapse under such conditions, whereby a widely accepted fluid-structure interaction analysis technique is adopted to realistically consider the phenomenon of green water impact loads. In addition, the structural behaviour of these breakwaters under green water impact loads is investigated simultaneously throughout the transient analysis. A verification study of the numerical results is performed using data from actual collapse incidents of breakwaters on container carriers. On the basis of the results of a series of numerical analyses, the pressure distribution of green water was accurately predicted with respect to wave mass and velocity. It is expected that the proposed analytical methodology and predicted pressure distribution could be used as a practical guideline for the design of breakwaters on container carriers.

• Smart Structures and Systems
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• v.31 no.6
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• pp.585-599
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• 2023

Field monitoring techniques offer an attractive approach for understanding bridge behavior under in-service loads. However, the investigations on bridge behavior under high-speed train load using field monitoring data are limited. The focus of this study is to explore the structural behavior of an in-service long-span steel truss arch bridge based on field monitoring data. First, the natural frequencies of the structure, as well as the train driving frequencies, are extracted. Then, the train-induced bearing displacement and structural strain are explored to identify the effects of train loads and bearings. Subsequently, a sensitivity analysis is performed for the impact factor of strain responses with respect to the train speed, train weight, and temperature to identify the fundamental issues affecting these responses. Additionally, a similar sensitivity analysis is conducted for the peak acceleration. The results indicate that the friction force in bearings provides residual deformations when two consecutive trains are in opposite directions. In addition, the impact factor and peak acceleration are primarily affected by train speed, particularly near train speeds that result in the resonance of the bridge response. The results can provide additional insight into the behavior of the long-span steel truss bridges under in-service high-speed train loads.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.21 no.4
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• pp.439-450
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• 2023

In this study, the impact load resulting from collision with the fuel rods of surrogate spent nuclear fuel (SNF) assemblies was measured during a rolling test based on an analysis of the data from surrogate SNF-loaded sea transportation tests. Unfortunately, during the sea transportation tests, excessive rolling motion occurred on the ship during the test, causing the assemblies to slip and collide with the canister. Hence, we designed and conducted a separate test to simulate rolling in sea transportation to determine whether such impact loads can occur under normal conditions of SNF transport, with the test conditions for the fuel assembly to slide within the basket experimentally determined. Rolling tests were conducted while varying the rolling angle and frequency to determine the angles and frequencies at which the assemblies experienced slippage. The test results show that slippage of SNF assemblies can occur at angles of approximately 14° or greater because of rolling motion, which can generate impact loads. However, this result exceeds the conditions under which a vessel can depart for coastal navigation, thus deviating from the normal conditions required for SNF transport. Consequently, it is not necessary to consider such loads when evaluating the integrity of SNFs under normal transportation conditions.

• Journal of Environmental Impact Assessment
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• v.21 no.2
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• pp.315-325
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• 2012

The characteristics of stormwater runoff and estimation of unit loads were examined in suburban industrial complex areas. During rainfall event, the peak concentrations occurred within the first 100 minutes after rainfall and then the highest concentration of NPS pollutants sharply decreased, showing strong first flush effect in suburban industrial complex. The cumulative load curves for NPS pollutants showed above the straight line, indicating that first flush effect occurred in suburban industrial complex. While the mean TSS, BOD, COD, TN and TP EMCs values were shown the highest values as 120.6 mg/L, 20.8 mg/L, 44.0 mg/L, 5.58 mg/L and 1.46 mg/L respectively. Unit loads estimated from the EMCs were TSS $43.86kg/km^2/day$, COD $52.45kg/km^2/day$, BOD $24.79kg/km^2/day$, T-N $6.65kg/km^2/day$, T-P $1.75kg/km^2/day$, and Pb $0.10kg/km^2/day$. Results of unit loads were compared with the unit pollutant loads from land-use in Korea and USA. The unit load of TSS was lower than that of USA. Estimated BOD and T-N and T-P unit loads were lower than that of Korea.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2008.04a
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• pp.561-566
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• 2008

Recently, because of development of the high speed train technology, the vibration loads by train is significantly increased ever than before. This buried gas pipelines are exposed to both repeated impact loads, and, moreover, they have been influencing by vibration loads than pipeline which is not located under vehicle loads. The vibration characteristic of pipeline is examined by dynamic analysis, and variable is only train speed. Since an effect of magnitude of vibration loads is more critical than cover depth, as increasing the train speed, the vibration speed of buried pipelines is also increased. The slope of vibration velocity is changed by attenuation of wave, at train speed, 300 km/h. From the analysis results, the vibration velocity of pipelines is satisfied with the vibration velocity criteria which are established by Korea Gas Corporation. The results present operation condition of pipelines under rail loads has fully sound integrity based on KOGAS specification.

• Journal of Environmental Impact Assessment
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• v.18 no.2
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• pp.59-67
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• 2009

Water quality of the Lake Youngrang in the Sokcho City is eutrophic. Jangcheon is the largest inflow source to the lake. Major pollutant sources are stormwater runoff from resort areas and various land uses in the Jangcheon watershed. A storm sewer on the southern end of the lake is also an important pollution source. In this study, water quality modelling for Lake Youngrang was carried out considering the rainfall-runoff pollution loads from the watershed. The rainfall-runoff curves and the rainfall-runoff pollutant load curves were derived from the rainfall-runoff survey data during the recent 4 years. The rainfall-runoff pollution loads and flow from the Jangcheon watershed and the storm sewer were estimated using the two kinds of curves, and they were used as the flow and the boundary data of the WASP model. With the measured water quality data of the year 2005 and 2006, WASP model was calibrated. Non-point pollution control measures such as wet pond and infiltration trench were considered as the alternative for water quality management of the lake. The predicted water quality were compared with those under the present condition, and the improvement effect of the lake water quality were analyzed.

• Journal of the Korean Institute of Gas
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• v.13 no.1
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• pp.1-8
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• 2009

Recently, the vibration of underground structure due to high speed railway loads has been increased substantially as compared with middle and slow speed. The buried gas pipelines under continuous impact forces and repeated loading are more influenced by the vibrational loads than another pipelines. However, the static analysis was not enough to allow for the effect of vibrations because it uses impact factors for the design or analysis process. In this study, characteristics of Pipelines was quantitatively estimated through each conditions of soil covers and train speed, and the new vibration prediction is presented about the vibrational velocity.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1997.04a
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• pp.42-48
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• 1997

The dynamic response of symmetric cross-ply and angle-ply composite laminated plates under impact loads is investigated using a higher order shear deformation theory. A modified Hertz law is used to predict the impact loads and a four node finite element is used to model the plate. By using a higher order shear deformation theory, the out-of-plane shear stresses, which can be a crucial factor in the failure of composite plates, are determined with significant accuracy. The results compared with previous investigations showed good agreement. The effect of ply sequence and ply angle on the contact force is also studied.