• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.1A
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• pp.69-78
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• 2008

In this study, in order to verify the reinforcement effects of the cracked concrete tubes and culverts, static load test was conducted. After the load carrying capacity of the original concrete tubes (nominal diameter 0.8 m, 1.0 m, 1.5 m) and box culverts (inner width 2.0 m. 2.5 m) was reduced by the cracking test, the cracked concrete specimens were strengthened by installing profile with steel stiffener and high strength mortar. And then, the maximum load tests were conducted the renewal concrete tubes and box culverts. According to the method application, the load carrying capacity increased 1.66~3.50 times than it of the original tubes before applying the method. In case of the original box culverts, the load carrying capacity increased 1.66~3.10 times than the case before installing profile and high strength mortar. Also non-linear analysis was carried out by using the commercial FEM program of ABAQUS 6.6. Solid (C3D8R) elements and concrete damage plasticity option was applied to the analysis. For reflecting confined reinforcing bars in the analysis, the composite material properties were used.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.1C
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• pp.53-62
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• 2008

A constitutive model, which can simulate the effect of principal stress rotation associated with direct simple shear test, is proposed in this study. The model is based on two mobilized planes. The plastic strains occur from the two mobilized planes, and depend on stress state, and they are added. The first plane is a plane of maximum shear stress, which rotates about the horizontal axis, and the second plane is a horizontal plane which is spatially fixed. The second plane is used to consider the effect of principal stress rotation on simple shear tests under different stress states. The soil skeleton behavior observed in drained simple shear tests is captured in the model. This constitutive model is incorporated into the dynamic coupled stress-flow finite difference program FLAC. The model is first calibrated with drained simple shear tests on loose Fraser River sand. The measured shear stress and volume change are partially induced by principal stress rotation and compared with model calculations. The model is verified by comparing predicted and measured settlements due to rigid footing resting on loose sands. Settlements predicted by the proposed model were very similar to measured settlements. Mohr-Coulomb model can not consider the effect of principal stress rotation and its prediction was only 20% of measured settlements.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.1A
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• pp.89-94
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• 2008

The problem of interaction between the structures interconnected at discrete points as like composite structures, has a attracted considerable attention for a prolonged period of time. Recently, mixed structures are applied for overcoming structural limits by developed countries. In this paper, advanced connection type of mixed structures are presented by numerical approach. Also it is performed on extensive literature review from theoretical method to numerical analysis. For analysing behaviors of mixed structures according to connection type, 2 different connections and 1 reinforced connection are compared by 3D nonlinear numerical analysis. Nonlinear analysis of mixed structures is carried out by utilizing contact elements of a general purpose structural analysis computer program(ABAQUS). By using 6 criteria, each connections are investigated. From this result, proper reinforcing and well designed connection type are proposed. And results also show that the deflections which are induced by discontinuity on mixed structures, has a linear distribution that should decrease as applying proposed connection type.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.3B
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• pp.311-319
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• 2006

A bed level change model(SED-FLUX) is introduced based on the realistic sediment transport process including bed load and suspended load behaviours at the bottom boundary layer. The model SED-FLUX includes wave module, hydrodynamic module and sediment transport and diffusion module that calculate suspended sediment concentration, net sediment erosion flux($Q_s$) and bed load flux. Bed load transport rate is evaluated by the van Rijn's TRANSPOR program which has been verified in wave-current fields. The net sediment erosion flux($Q_s$) at the bottom is evaluated as a source/sink term in the numerical sediment diffusion model where the suspended sediment concentration becomes a verification parameter of the $Q_s$. Bed level change module calculates a bed level change amount(${\Delta}h_{i,j}$) and updates a bed level. For the model verification the limit depth of the bed load transport is compared with the field experiment data and some formula on the threshold depth for the bed load movement by waves and currents. This model is applied to the beach profile changes by waves, then the model shows a clear erosion and accumulation profile according to the incident wave characteristics. Finally the beach evolution by waves and wave-induced currents behind the offshore breakwater is calculated, where the model shows a tombolo formation in the landward area of the breakwater.

• Journal of the Korean Society of Food Culture
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• v.22 no.1
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• pp.127-139
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• 2007

This research was peformed to investigate the anthropometric data, blood profiles, and nutrient intakes of elderly persons living in a rural area. The subjects were 67 undernourished people who participated in follow-up nutrition intervention programs for9 weeks. Anthropometric data showed that the mean heights and weights in the management group were 157.6 cm and 59.1 kg, respectively, for the males and 152.6 cm and 51.0 kg, respectively, for the females. The mean BMIs of the management group were 23.8 kg/m$^2$ in the males and 22.4 kg/m$^2$ in the females. The total cholesterol, HDL-cholesterol, and albumin levels of the subjects were 181.7-191.4mg/dL, 48.3-53.0mg/dL, and 3.85-4.00g/dL, respectively. Energy, ash, P, Na, vitamin B$_1$, vitamin B$_2$, vitamin B$_6$, and niacin increased significantly after intervention for the management group. The mINQ, however, did not significantly increase after intervention. Also after intervention, there was no significant difference in mINQ between the management group and the comparison group. MAR (14) in the management group was significantly increased from 0.62${\pm}$0.2 before intervention to 0.68${\pm}$0.2 after intervention (p=0.022), and it was significantly different between the management group and the comparison group (p=0.017). MAR (8) in the management group was not significantly different (p=0.915) before and after intervention. However, MAR (8) between the management group and the comparison group did show a significant difference (p=0.031). MAR (3) in the management group was significantly increased from 0.48${\pm}$0.2 before intervention to 0.55${\pm}$0.2 after intervention (p=0.045), however, MAR (3) was not significantly different between the management group and the comparison group (p=0.093). For the probability of nutrient insufficiency, in the management group the probability of nutrient values below the EAR (except for Fe) decreased after intervention compared to before intervention. On the other hand, the probabilities of values above the RI, or EAR${\sim}$RI, were increased

• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.6D
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• pp.761-770
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• 2009

The energy efficiency and environment-friendly aspect of the railway system would be superior to other on-land ransportation systems. In a preliminary feasibility study stage and selection of optimal railway route, the energy efficiency and problems related to environment are usually considered. For the selection of optimal railway route, geographical features and facility of management are generally considered. Environment effect factors for the selection of environment-friendly railway router are focused and studied in this paper. In this study, various analysis of opinion of specialists (railway, environment, transport, urban planning, survey) and the guideline for construction of environment-friendly railway were accomplished. From these results of various analysis, 7 major categories (topography/geology, flora and fauna, Nature Property, air quality, water quality, noise/vibration, visual impact/cultural assets) were extracted. To select environment friendly railway route, many alternatives should be compared optimal route must be selected by a comprehensive assessment considering these 7 categories. To solve this problem, the selected method was AHP which simplifies the complex problems utilizing hierarchy, quantifying qualitative problems through 1:1 comparison, and extracting objective conclusions by maintaining consistency. As a result, a GUIbased program was developed which provides basic values of weighted parameters of each category defined by specialists, and a quantification of detailed assessment guidelines to ensures consistency.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.5D
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• pp.797-804
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• 2006

A development of regression model for asphalt concrete pavements using Falling Weight Deflectometer deflections is presented in this paper. A backcalculation program based on layered elastic theory was used to generate the synthetic modulus database, which was used to generate 95% confidence intervals of modulus in each layer. Using deflection basins of FWD data used in developing this procedure were collected from Pavement Management System in flexible pavements. Assumptions of back-calculation are that one is 3 layered flexible pavement structure and another is depth to bedrock is finite. It is found that difference of between 95% confidence intervals and modulus ranges of other papers does not exist. So, the data of 95% confidence intervals in each layer was used to develop multiple regression models. Multiple regression equations of each layer were established by SPSS, package of Statics analysis. These models were proved by regression diagnostics, which include case analysis, multi-collinearity analysis, influence diagnostics and analysis of variance. And these models have higher degree of coefficient of determination than 0.75. So this models were applied to predict modulus of domestic asphalt concrete pavement at FWD field test.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.6D
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• pp.951-960
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• 2006

Structural pavement analysis considering lateral loads of moving vehicle was carried out in order to simulate passing vehicle loads under various interface conditions. To verify of existing multi-layer elastic analysis of layer interface effect parameters, this study compared outputs by using ABAQUS, a three dimensional finite element program and KENLAYER, multi-layer elastic analysis as vertical load was applied to the surface of asphalt pavements. Pavement performance depending on interface conditions was quantitatively evaluated and fundamental study of layer interface effect parameters was performed in this study. As results of the study, if only vertical loads of moving vehicle is applied, subdivision of either fully bonded or fully unbonded is enough to indicate interface effect parameters. On the other hand, when lateral loads are applied with vertical loads, pavement behavior and performance are greatly changed with respect to layer interface conditions. The thinner thickness of the asphalt layer is and the smaller elastic moduli of the asphalt layer is, the more pavement behavior is influenced by interface conditions. In addition, regression analysis equation analytically computing tensile strain which was considered thicknesses and elastic moduli of the asphalt layer and layer interface effect parameters at the bottom of the asphalt layer was presented using database from numerical analyses on national pavement model sections.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.30 no.4A
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• pp.337-342
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• 2010

Generally most sluice gates are closed and opened by a mechanical winch, a winch using an oil-pressure, or a winch mixing both. Because of their size and structure, they should be safely operated with more than two pulling devices helping each other. At the moment of their opening and closing, there usually occur some additional loads to the structure which cannot be exactly measurable at the stage of designing. Such additional loads can cause the sluice gate to be unbalanced and make it hard to open and close the gate, and by also overloading a winch, they can inflict a significant damage to the safety of the sluice gate. This paper explains a FDC(Force-Displacement Control) system which simultaneously considered the oil-pressure and displacement in order to evenly distribute the force and make a winch balanced at the opening and closing motion. This FDC system was implemented by means of the PID(Proportional Integral Derivative) function of XG 5000 program. It was experimented on a model of the sluice gate winch with the hydraulic oil pressure cylinder. The experiments showed that the developed FDC system made the winch of hydraulic oil pressure cylinder open and close cooperatively in spite of various external loads. Therefore the FDC system is proven effective when it is applied to a winch of sluice gate.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.2A
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• pp.119-130
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• 2009

Seismic fragility curves of a structure represent the probability of exceeding the prescribed structural damage state for a given various levels of ground motion intensity such as peak ground acceleration (PGA), spectral acceleration ($S_a$) and spectral displacement ($S_d$). So those are very essential to evaluate the structural seismic performance and seismic risk. The purpose of this paper is to develop seismic fragility curves for PSC box girder bridges. In order to construct numerical fragility curve of bridge structure using nonlinear time history analysis, a set of ground motions corresponding to design spectrum are artificially generated. Assuming a lognormal distribution, the fragility curve is estimated by using the methodology proposed by Shinozuka et al. PGA is simple and generally used parameter in fragility curve as ground motion intensity. However, the PGA has not good relationship with the inelastic structural behavior. So, $S_a$ and $S_d$ with more direct relationship for structural damage are used in fragility analysis as more useful intensity measures instead of PGA. The numerical fragility curves based on nonlinear time history analysis are compared with those obtained from simple method suggested in HAZUS program.