• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.285-288
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• 2008

A model for the effective moment of inertia $I_{\epsilon}$ as expressed in Branson's equation, in which reduction of the flexural rigidity of RC beams due to cracking are aptly taken into accoun,t is presented. However, KCI Code isn`t considered tension stiffening as it is in debonding of reinforcing bar. Therefore, this equation need to set up suitable to our design Code. The experimental work consisted of casting and testing a total of 6 simply supported reinforced concrete beams and a total of 4 continuos reinforced concrete beams under two point concentrated loads. Main parameters are concrete strength, coverage, bond between concrete and reinforcing bars, are known as have an effect on deflection and tension stiffening. Every test beams had the same $250{\times}350$mm rectangular section, with a simply supported clear span of 4,400 mm and a continuos clear span of 6,500 mm. Comparison of the test results with values obtained using the KCI Code equation of the effective moment of inertia showed a noticeable difference.

• Journal of Korea Water Resources Association
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• v.43 no.1
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• pp.105-117
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• 2010

This paper presents a new and simple technique to perform MUSCL reconstruction for solving 2D shallow water equations. The modified MUSCL scheme uses weighted area ratio to apply non-uniform grid in stead of the previous method that equally distributed the difference of conservation variables to each interface. The suggested method can physically reconstruct conservation variables in case of uniform grid as well as non-uniform grid. In this study, Unsplit scheme applicable to unstructured grid is used and efficient slope limiter of TVD scheme is used to control numerical oscillation which can be occurred in modified MUSCL scheme. For accurate and efficient treatment of bed slope term, the modified MUSCL scheme is coupled with the surface gradient method. The finite volume model applied to suggested scheme is verified through a comparison between numerical solution and laboratory measurements data such as the simulations of isolated building test case and Bellos's dam break test case.

• Journal of the Korean Institute of Navigation
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• v.25 no.1
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• pp.45-52
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• 2001

The purpose of this study is the optimum modification of dynamic characteristics of stiffened plate structure. In the method of the optimization, finite element method(FEM), sensitivity analysis and optimum structural modification method are used. To begin with, using FEM, the dynamic characteristics of stiffened plate structure is analyzed. Next, rate of change of dynamic characteristics by the change of design variable is calculated using the sensitivity analysis. Then, amount of change of design variable is calculated using this sensitivity value and optimum structural modification method. The change of natural frequency is made to be an objective function. Thickness of plate and cross section moment become a design variable. It is shown that the results are effective in the optimum modification for dynamic characteristics of the stiffened plate structure.

• Journal of the Korean Society for Marine Environment & Energy
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• v.13 no.3
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• pp.174-180
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• 2010

The inhomogeneous Helmholtz equation is introduced for variable water depth and potential function and separation of variables are introduced for the derivation. Only harmonic wave motions are considered. The governing equation composed of the potential function for irrotational flow is directly applied to the still water level, and the inhomogeneous Helmholtz equation for variable water depth is obtained. By introducing the wave amplitude and wave phase gradient the governing equation with complex potential function is transformed into two equations of real variables. The transformed equations are the first and second-order ordinary differential equations, respectively, and can be solved in a forward marching manner when proper boundary values are supplied, i.e. the wave amplitude, the wave amplitude gradient, and the wave phase gradient at a side boundary. Simple spatially-centered finite difference numerical schemes are adopted to solve the present set of equations. The equation set is applied to two test cases, Booij’ inclined plane slope profile, and Bragg’ wavy bed profile. The present equations set is satisfactorily verified against other theories including the full linear equation, Massel's modified mild-slope equation, and Berkhoff's mild-slope equation etc.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2022.05a
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• pp.587-588
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• 2022

In this paper, we propose a rigid body tracking method in 3D space using 2D passive marker images from multiple motion capture cameras. First, a calibration process using a chess board is performed to obtain the internal variables of individual cameras, and in the second calibration process, the triangular structure with three markers is moved so that all cameras can observe it, and then the accumulated data for each frame is calculated. Correction and update of relative position information between cameras. After that, the three-dimensional coordinates of the three markers were restored through the process of converting the coordinate system of each camera into the 3D world coordinate system, the distance between each marker was calculated, and the difference with the actual distance was compared. As a result, an error within an average of 2mm was measured.

• Journal of the Korea institute for structural maintenance and inspection
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• v.19 no.2
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• pp.84-91
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• 2015

In this paper, to overcome disadvantages of existing lining boards, the parametric studies to evaluate safety and verify performance of newly suggested lining boards was performed. Since the calculated stresses of steel plates are lower than the allowable stress for considered all analytical variables, end reinforcement locations, and crane rail loads, it can be concluded that the suggested lining board is structurally safe. Where, "$3,000{\times}2,000{\times}6t$" was select to be optimized cross-section and the reinforcement from the end to 200mm to the internal direction looks like the best case. In addition, the suggested lining board is economical since the steel amount per unit area compared to existing lining board is reduced by 36% and it can apply to the lining structural system of subway and underpass since construction speed is past due to the less installation number of lining boards.

• The korean journal of orthodontics
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• v.25 no.2 s.49
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• pp.129-142
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• 1995

The purpose of this study was to estimate correlations of craniocervical posture and craniofacial morphology in Korean young adults. The sample consisted of 50 young adults (25 males and 25 females) who had good profile and Class I molar relationship. The analysis of craniocervical posture and craniofacial morphology was performed on lateral cephalograms taken in natural head position. The results were as follows, 1. The mean and the standard deviation of postural and morphologic variables were obtained. 2. Korean young adult had cervical lordosis of which degree between OPT and CVT shows $3.55{\pm}2.58^{\circ}$ 3. Craniocervical posture and each of vertical ratio, facial prognathism, mandibular rotation showed high correlation. 4. Correlation coefficients between postural variables and each of intermaxillary relation, anteroposterior ratio were low. 5. The head positioning error of natural head position was smaller than the inter-individual variability of postural variables.

• Korean Journal of Soil Science and Fertilizer
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• v.17 no.4
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• pp.319-324
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• 1984

Spatial variability of sand, silt, and clay contents on Hwadong SiCL and Jungdong SL was studied by using geostatistical concept. The measurements were made within a $33{\times}14m^2$ area at the nodes of 2 by 2m grids. The validity of all assumptions (stationarity, variogram models, etc.) was proved by Jack-knifing procedure and frequency distribution performed on the original data grids. The variogram of sand content on Hwadong SiCL was different from the linear model and that of clay content of Jungdong SL the linear and the spherical model in calculation of both kriged values and kriged variances in identification of its choice for simplicity.

• Journal of Korea Water Resources Association
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• v.33 no.6
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• pp.783-791
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• 2000

A multidimensional representation for precipitation, given In the theory proposed by E. Waymire et al. (1984), is used for simulating rainfall in space and time. The model produces moving storms with realistic meso-scale meteorological features in time and space. The first- and second-order statistics derived from observed JX)int gauge data were used to estimate the model parameters based on the Nelder-Mead algorithm of optimization. Then twelve-year traces of rainfall intensities at fixed gage stations were generated at intervals of 1 hours. First- and second-order statistics are evaluated from the above series, which are used for estimating the parameters of one dimensional model of temporal rainfall at a point. As a result from the comparisons of one dimensional model parameters used observed and generated data from multidimensional model, we found that the multidimensional rainfall model generated visually realistic spatial patterns of rainfall as well as realistic temporal hyetographs of rainfall at a point. point.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.40 no.3
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• pp.181-189
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• 2016

An analytical model was developed by Sim to estimate the two-phase damping ratio for upward two-phase flow perpendicular to horizontal tube bundles. The parameters of two-phase flow, such as void fraction and pressure loss evaluated in the model, were calculated based on existing experimental formulations. However, it is necessary to implement a few improvements in the formulations for the case of tube bundles. For the purpose of the improved formulation, we need more information about the two-phase parameters, which can be found through experimental test. An experiment is performed with a typical normal square array of cylinders subjected to the two-phase flow of air-water in the tube bundles, to calculate the two-phase Euler number and the two-phase friction multiplier. The pitch-to-diameter ratio is 1.35 and the diameter of cylinder is 18mm. Pressure loss along the flow direction in the tube bundles is measured with a pressure transducer and data acquisition system to calculate the two-phase Euler number and the two-phase friction multiplier. The void fraction model by Feenstra et al. is used to estimate the void fraction of the two-phase flow in tube bundles. The experimental results of the two phase friction multiplier and two-phase Euler number for homogeneous and non-homogeneous two-phase flows are compared and evaluated against the analytical results given by Sim's model.