• Proceedings of the Korea Water Resources Association Conference
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• 2008.05a
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• pp.1934-1938
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• 2008

In this study, the landuse pattern at the Gab river is analyzed using time-series aerial images. This study area is divided by two zones like as inland and floodplain. To begin with, in inland, the landuse area of items such as residential, road, industrial, public facilities is increased by following the urbanization. On the other hand, the area of the other items such as agricultural, forest and river is decreased. Also, the inclination of those two groups is reversed around 1988. Form the results, it is clarified that the Gab river is urbanized around 1988. In floodplain, the area of river is decreased as time goes by. This result means that the area of landuse factors such as level-upped riverside land, bridge, head work is increased conversely. Also, the proportion of the water to the river considering the hydrologic factor like rainfall is increased as time goes by. Overall, it is concluded that aerial image can be applied to get a landuse information that is needed in river management and planning.

• Journal of the Earthquake Engineering Society of Korea
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• v.15 no.4
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• pp.1-12
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• 2011

Seismic fragility analysis has been developed to evaluate the seismic performance of existing nuclear power plants, but now its applicability has been extended to buildings and bridges. In general, the seismic fragility curves are evaluated from the nonlinear time-history analysis (THA) using many earthquake ground motions. Seismic fragility analysis using the nonlinear THA requires a time consuming process of structural modeling and analysis. To overcome this shortcoming of the nonlinear THA, simplified methods such as the displacement coefficient method (DCM) and the capacity spectrum method (CSM) are used for the seismic fragility analysis. In order to evaluate the accuracy of the seismic fragility curve calculated by the DCM and the CSM, the seismic fragility curves of a reinforced concrete shear wall structure calculated by the DCM and CSM are compared with those calculated by the nonlinear THA. In order to construct a numerical fragility curve, 190 artificially generated ground motions corresponding to the design spectrum and the methodology proposed by Shinozuka et al. are used.

• Journal of the Earthquake Engineering Society of Korea
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• v.14 no.2
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• pp.37-47
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• 2010

In order to attain enhanced seismic performance of RC bridges, premature shear failure prior to the achievement of target ductilities of the piers should be prevented. For this purpose, a reliable shear strength evaluation is required. The shear strength of an RC column subjected to a lateral force decreases with an increase in ductility. Many empirical equations for the shear strength have been proposed by many researchers. However, there are many discrepancies in the initial shear strength in the low ductility range, and in the decrease rate according to the ductility. In this study, a new empirical equation of shear strength considering the displacement ductility effect has been proposed, in which the initial shear strength equation proposed by the authors was revised on the basis of the investigation of many other researchers' test results. The resulting improvement in accuracy is confirmed by comparison with other empirical equations.

• Journal of Korean Society of Steel Construction
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• v.23 no.3
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• pp.397-404
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• 2011

In this paper, a research for the dynamic wheel loads of a 3D vehicle model, which relates to a tire-enveloping model, is carried out. A single truck with four axles is modeled as a 10-D.O.F. vehicle by modeling both contact length of tires and pitching of tandem spring axles. The dynamic equations of the vehicle are obtained using the Lagrange's equation, the solution of the equations is calculated by Newmark-${\beta}$ method. The validity of the developed 3D vehicle model is demonstrated by comparing results obtained from the proposed method with those from experimental data. The maximum impact factors of tire force are evaluated according to the various step bumps on which a 24-ton dump truck is running.

• Proceedings of the Korean Geotechical Society Conference
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• 2007.09a
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• pp.665-678
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• 2007

It was applied the grouting method to fill densely the space between the bottom of the caisson and the ground with the grout mixture mixed with anti-washout admixture after locating accurately the precast caisson on three concrete landing pads but it is far different from a costly conventional method, which place concrete to build the foundation of reinforcement concrete on the spot after excavating inside of the temporary coffering wall for the bridge foundation in the sea. To verify the grouting method in advance, the full-scale trial test was performed twice on the land. After confirming the fluidity of material for the injection and some possible problems during construction and then enhancing the original design, the main process is ongoing and it has been finished 12 spots until now. The purpose of this study is to introduces for the first time in Korea the grouting method including the automatic and the manual monitoring process applied to, based on the main process of the caisson foundation finished already in the site. In a similar construction it is sincerely expected to be referred to in the future.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.341-344
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• 2008

Lightweight concrete is known for its advantage of reducing the self-weight of the structures, reducing the areas of sectional members as well as making the construction convenient. Thus the construction cost can be saved when applied to structures such as long-span bridge and high rise building. However, the lightweight concrete requires specific mix design method that is quite different from the typical concrete, since using the typical mix method would give rise the material segregation as well as lower the strength by the reduced weight of the aggregate. In order to avoid such problems, it is recommended to apply the mix design method of self-consolidating concrete for the lightweight concrete. Therefore experimental tests were performed as such mechanical properties(compressive strength, dry density and structural efficiency) of concrete and dry shrinkage according to ACI committee 209.

• Spatial Information Research
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• v.9 no.1
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• pp.125-135
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• 2001

Ground failure such as landslide, rock fall land subsidence by heavy rainfall have damaged to people and property. Especially, the damage to important facility such as dam, bridge, tunnel and industrial complex may be possible. Therefore the ground failure must be assessed and counter plan must be prepared. So, the object of this study is to develop the spatial information system for regional ground stability assessment. For this, the topographic, geologic, soil, forest, land use, rainfall frequency map, and satellite image near 40 dams were collected and constructed to the spatial information system. The spatial information system was developed using Avenue in ArcView 3.2 environment and consists of pull down menus and icons. For application of the spatial information system, regional ground stability was assessed in Andong dam. The assessment was ground failure susceptibility and possibility. The spatial information can be used for regional ground stability assessment, prevention and mitigation of hazard, and management of ground as basic data.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.13 no.5
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• pp.173-181
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• 1993

Under natural conditions, rivers do not in general take straight courses but instead take winding courses. This is known as meandering of rivers. Meandering of rivers are so complicated because of the mutual interactions between flow and movable boundaries. In quantitative information, it is important to predict the future location of a river channel(channel migration) because in selecting a bridge site or a location of a road. It may be valuable to know the future impact of a nearby river on those structures. When the prediction model of the migration of channel is used in domestic rivers with high coefficient of river regime, it is rational to use the periodical dominant discharge (PDD), which is named firstly by the author, instead of the average discharge. According to the analysis of the erosion coefficient, the mean deviation on the channel migration, and the bed scour factor, it can bring shedding light on the fact that the discharge is one of the dominant components in channel migration. In project area, the discharge that can shift the channel is slightly greater than 6,000CMS. The prediction model of the migration of channel estimated the erosion coefficient, $E_0$ by the data from the South Han River. This estimated value from the South Han River was also used to predict the migration of the South Han River in year 2000.

• Journal of the Korean Society for Railway
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• v.13 no.5
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• pp.521-527
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• 2010

The Paved Track is applied to reduce maintenance cost of conventional line. The Paved Track could be used in all types of lines including earthwork, bridge, tunnel and turnout sections. In case of earthwork section, the construction joint is the most critical factor to track durability. The construction joint does not affect to the track structure directly, but the gap due to discontinuity of slabs may affect to the long-term serviceability. To evaluate this problem, the accelerated track test has been performed on the construction joint and the middle part to of the real scale Paved Track. The purpose of this test is that evaluate the vulnerability of construction joint section comparing the trends of settlement and earth pressure under repeated loads of construction joint with those of the middle slab part.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.36 no.2
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• pp.277-283
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• 2016

Recently, the interests in three-dimensional design and BIM(Building Information Modeling) are increasing in civil engineering sector and the researches about three-dimensional design and quantity take-off methods for civil engineering structures have been conducted. However, these studies are just carried out the 3D design and quantity calculation of civil structures on the road or railway such as bridges and tunnels. The study on the quantity take-off methods and the evaluation of calculated results on the earth works should be performed in more detail. Based on these backgrounds in mind, the study was conducted the three-dimensional road design and evaluated the quantity take-off results on the earth works using 3D calculation method(average end area method, prismoidal method and composit method). The calculated quantity from composit method showed about 5% error of measuring efficiency than the average end area method, and when reporting the quantity calculation of earth works, it is necessary to specify the calculation method using quantity take-off of earth works.