• Steel and Composite Structures
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• v.15 no.3
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• pp.247-266
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• 2013

This paper presents a comparison of results obtained by a newly developed numerical model for predicting the behaviour of structures under fire with experimental study carried out on heated and simply supported steel beam elements. A newly developed numerical model consists of three submodels: 3D beam model designed for calculating the inner forces in the structure, 2D model designed for calculation of stress and strain distribution over the cross section, including the section stiffness, and 3D transient nonlinear heat transfer model that is capable of calculating the temperature distribution along the structure, and the distribution over the cross section as well. Predictions of the calculated temperatures and vertical deflections obtained by the numerical model are compared with the results of the inhouse experiment in which steel beam element under load was heated for 90 minutes.

• Proceedings of the KSME Conference
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• 2004.11a
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• pp.1466-1471
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• 2004

In this paper, we report the numerical and experimental solutions of the axi-symmetric flows in the axial plane driven by an impingement of fluid from the bottom wall of a circular cylinder. We managed to visualize successfully the flow pattern shown on the vertical plane through the container axis. The numerical results are not show to compare well with the experimental results for the case of the Rossby number 3. Because the numerical results calculate on the assumption that vortex flows are axi-symmetric flow on the other hand real experimental results are show asymmetric flow. The numerical solutions reveal that inertial oscillation plays an important role at small Rossby numbers, or at a larger background rotation.

• Proceedings of the Korea Concrete Institute Conference
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• 2002.05a
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• pp.455-460
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• 2002

In this study, a numerical analysis that can effectively predict the effect of strengthening of cracked flexural members is developed using axial deformation link elements. Concrete and interface between concrete and repair material are considered as quasi-brittle material. Reinforcing bars and reinforcing steel plates are assumed to perform as elasto-plastic materials. Unloading behavior of axial deformation link element is implemented. In the developed numerical model, a flexural member is intentionally cracked by pre-loading, then, the cracked member is repaired using extra elements, and reloaded. The results from analysis of repaired flexural members agrees well with available experiment results. Also, it was shown that the effect of strengthening and the change of failure mode with respect to the time for strengthening and thickness of repair materials. Based on the results, it was determined that the developed numerical model has a good agreement for determining failure modes and effect of strengthening in cracked flexural members. By utilizing the developed numerical analysis, the time and dimension of external strengthening in an existing cracked flexural member with predition of failure mechanism can be determined.

• Journal of information and communication convergence engineering
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• v.12 no.1
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• pp.39-45
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• 2014

A numerical method for solving Hamiltonian equations is said to be symplectic if it preserves the symplectic structure associated with the equations. Various symplectic methods are widely used in many fields of science and technology. A symplectic method preserves an approximate Hamiltonian perturbed from the original Hamiltonian. It theoretically supports the effectiveness of symplectic methods for long-term integration. Although it is also related to long-term integration, numerical stability of symplectic methods have received little attention. In this paper, we consider explicit symplectic methods defined for Hamiltonian equations with Hamiltonians of the special form, and study their numerical stability using the harmonic oscillator as a test equation. We propose a new stability criterion and clarify the stability of some existing methods that are visually based on the criterion. We also derive a new method that is better than the existing methods with respect to a Courant-Friedrichs-Lewy condition for hyperbolic equations; this new method is tested through a numerical experiment with a nonlinear wave equation.

• Proceedings of the Korean Geotechical Society Conference
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• 2002.03a
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• pp.197-204
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• 2002

In this study, multivariate analysis based on domestic data(958 EA) of road tunnel, and suggest the easy prediction equation of Q-system. We generate applicable Q-value to numerical analysis method with using the equation and investigate the behavior as variable Q-value of rock mass induced excavation with discontinuum numerical analysis method, UDEC. In the result of the experiment, we research the application range of Q-value to apply the continuum model to discontinuous rock mass is below 0.7 and we testify the applicability of continuum model as researched Q-value with continuum numerical analysis method, FLAC.

• 한국가시화정보학회:학술대회논문집
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• 2006.12a
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• pp.86-91
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• 2006

In this parer, we present the bubble forming and motion in the micro channel by using the two-dimensional numerical computation and experiment. In the numerical computation, The Lattice Boltzmann method(LBM) and free-energy model is used to treat the interfacial force and deformation of binary fluid system, drawn in to a micro channel and a numerical simulation is carried out by using the parallel computation method. The urn in this investigation is to examine the applicability of LBM to numerical analysis and experimental method of binary fluid separation and motion in the micro channel.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.43 no.1
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• pp.38-48
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• 2007

Numerical modeling was used to evaluate the submerging characteristics of the submersible fish cage system operated by compressed air. The submerging characteristics calculated by numerical analysis as the cage was moved up and down were nearly identical to existing experiment results. Thus, the numerical model proposed in this study could be very useful in analyzing various parameters required for optimizing the design of a submersible fish cage system operated by compressed air.

• The Journal of Internal Korean Medicine
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• v.26 no.1
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• pp.12-47
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• 2005

First, mice were dosed with 50mg/kg of streptozotocin(STZ) twice every 24 hours to cause high blood-sugar. Then, after three days, mice were injected with 100mg/kg of STZ again. Two different dosages of Saengjihwangeumja-gami were given to the experiment groups: SA group, 15mg/kg/day, and SB group, 90mg/kg/day, in order to determine the effects of Saengjihwangeumja-gami, which has been known to be good for DM(Diabetes Mellitus). By observing weight and blood-sugar level changes, blood tolerance, the numerical value of BUN(Blood Urea Nitrogen) and creatinine in blood, and through light-electronicmicroscopic and immunohistologic investigations of pancreas and kidneys, the following results were obtained: 1. The experiment groups showed a high suppressive effect of weight-loss. 2. The experiment groups' blood-sugar and blood tolerance showed an effective lowering of blood-sugar levels. 3. The experiment groups did not show any noticeable change in the numerical value of BUN and creatinine in blood compared with that of the control groups. 4. The experiment groups showed a higher Insulin positive reaction of pancreatic islets ${/beta}-cell$ than the control groups. 5. The experiment groups showed a higher immuno-reaction against IGF- II than the control groups. 6. Observation of apoptosis of the pancreatic islets showed that the cells of experiment groups were less injured compared with those of the control groups, and fewer apoptag-positive reaction cells were seen in experiment groups than in the control groups. 7. Uunder electron-microscopy, the insulin-containing granules in pancreatic islets ${/beta}-cells$ had increased more in the experiment groups than in the control groups. 8. Under light microscopy, the injury on the inner & outer membrane of the glomerulus and epithelial cells of capillaries and cells among vessels were fewer in the experiment groups than in the control groups. 9. More apoptag-positive reaction cells in the kidney were seen in the control groups than in the experiment groups. 10. PAS-positive reaction substances had increased more in the substrate among the vessels of a glomerulus belonging to the control group than those of the experiment group. 11. Uunder electron-microscopy, the nucleonic membrane, nucleoplasm and mitochondria of proximal and distal renal tubular were more injured in the control groups than in the experiment groups. In conclusion, strong evidence for the efficacy of Saengjihwangeumja-gami in lowering blood-sugar, and in recovery and generation of pancreatic tissues injured by DM was observed. Results suggest Saengjihwangeumja-gami is an effective treatment for DM. Further study of the principles of blood-sugar dropping effects of Saengjihwangeumja-gami are needed, as well as further study of recovery and regeneration of pancreatic tissues injured by DM.

• Journal of Hydrogen and New Energy
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• v.25 no.5
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• pp.550-559
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• 2014

Hydraulic performance of the 1 inch ball valve have been analyzed based on the three-dimensional Reynolds-averaged Navier-Stokes analysis and an experiment. The experimental test rig of the 1 inch ball valve has been developed to investigate pressure drop for the 1 inch ball valve. The numerical model, which has reliability and effectiveness, has been constructed through the grid dependency test and validation with the results of the experiment. Shear stress transport turbulence model has been used to enhance an accuracy of the turbulence prediction in the pipeline and ball valve, respectively. Effects of the ball valve angle on the flow characteristics and friction performance have been evaluated.

• Journal of Korean Society on Water Environment
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• v.25 no.2
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• pp.181-192
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• 2009

In this study, the hydrological properties of permeable pavement were analyzed by the experiment and the numerical simulation. The numerical model used was a modified SWMM especially for considering the hydrological response of permeable pavement. The parameters of modified SWMM were revised by the experimental results, and then the practicability was evaluated through the comparison of the experimental and numerical simulation results. In the experiments, three different rainfall intensities such as 65 mm/hr, 90 mm/hr, 95 mm/hr were supplied for 4 hrs, and the hydraulic properties including surface outflow, subsurface outflow, ground water level, soil water contents were measured for 10 hrs. The results showed rainfall intensity effected directly on surface outflow volume and subsurface outflow volume was more effected by ground water level than rainfall intensity. The ground water level and the soil water contents were under estimated as compared with the experimental data except the portion of occurring direct runoff. The surface and subsurface outflow discharge were simulated very well in comparison with the experimental data. Consequently, the modified SWMM could be used very effectively to evaluate the hydrological property of permeable pavement.