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Pohang, South Korea

Lee Y.,Seoyeong Engineering Co. | Seo B.,SACS Korea Inc. | Lee E.-T.,Chung - Ang University
International Journal of Steel Structures | Year: 2015

Offshore structures like jackets are exposed to various kinds of external loading conditions and examination of broader range of modes and natural frequencies are required for their dynamic analysis. In this study, four model reduction techniques — two modal truncation methods and two balanced truncation methods — are introduced and applied to a jacket structure. The reduction results are compared with those of the conventional Paz condensation methods. Four new methods show better fidelity, especially in high frequency ranges than the conventional methods. © 2014, Korean Society of Steel Construction and Springer-Verlag Berlin Heidelberg.

Ahn J.,Pusan National University | Jung J.,Pusan National University | Kim S.,Pusan National University | Han S.-I.,Seoyeong Engineering Co.
International Journal of GEOMATE | Year: 2014

The use of permeable pavement is one of the most promising tools to control runoff and water quality, therefore enabling low impact development (LID), along with several other benefits. The porosity of the permeable pavement is the most important property of the pavement in current state of the practice. In this article, the porosity of a pervious concrete sample made in laboratory was evaluated by two approaches: measuring weights and X-ray image analysis. Two different X-ray imaging apparatus, 2D and 3D, were used to construct cross-sectional planar images of a cylindrical pervious concrete sample. It was found that the porosity estimate from 2D X-ray was close to the results with measuring weights, but that of 3D X-ray was rather larger under Xray imaging configuration and image analysis technique used. The viability of using X-ray images to evaluate the pore characteristics of permeable pavement, and future applications are discussed. © 2014, International Journal of GEOMATE.

Seong D.,Sungkyunkwan University | Kim T.,Samsung | Oh M.,Seoyeong Engineering Co. | Shin H.,Sungkyunkwan University
Journal of Advanced Concrete Technology | Year: 2011

Despite its importance in the seismic performance of an overall structure, our understanding of the ductility capacity of high-strength concrete (HSC) columns under various loading conditions is relatively limited compared to that of normal- strength concrete (NSC) columns. This study aims to evaluate the seismic performance of HSC columns through a numerical analysis approach. Based on the smeared crack concept, the analysis model consisted of material models for concrete and embedded reinforcement. The brittle behavior and smooth crack surfaces of HSC are some of its main drawbacks in engineering practice. In the proposed models, the shear retention mechanism along the crack surface correctly considered the smooth crack surfaces of HSC, and the confining effect of the column core was taken into account by modifying the concrete compressive model according to an appropriate confinement model for HSC. As part of the investigation, five large-scale HSC columns were constructed and tested under simulated seismic loading. The proposed numerical method was applied in predicting the seismic performance of various HSC columns tested in this research program and obtained from other research in the literature. The analytically predicted hysteretic behavior, ductility level, and failure mode of the columns showed reasonable agreement with experimental data. Copyright © 2011 Japan Concrete Institute.

Suh J.,Seoul National University | Choi Y.,Pennsylvania State University | Roh T.-D.,Seoul National University | Lee H.-J.,Seoyeong Engineering Co. | Park H.-D.,Seoul National University
Environmental Earth Sciences | Year: 2011

The objective of this study is to perform a preliminary national-scale assessment of the landslide susceptibility of rock-cut slopes along expressways in Korea. A geographic information system (GIS) database was compiled based on data from topographical and geological maps, and rock-cut slope data, including the locations of past landslides. Seven factors (i. e., slope height, slope length, slope gradient, upper slope gradient, lithology, distance from nearest fault, and dip direction of slope) were extracted from the GIS database to assess the relationship between each factor and landslide events. Weight of evidence (WOE), analytic hierarchy process (AHP), and fuzzy logic methods, as well as hybrid methods, were used to establish the rating of classes for each factor, weightings for the factors, and to combine multiple factor layers into landslide-susceptibility maps. A comparison of the results obtained using several different methods, based on the area under curve technique, revealed that the WOE method showed the highest accuracy of 74%. The annual cost of traffic congestion resulting from slope failures was evaluated to identify those rock-cut slopes where detailed investigations and landslide warning systems are required. © 2010 Springer-Verlag.

Jung Y.-W.,Seoyeong Engineering Co. | Han S.-I.,Seoyeong Engineering Co. | Jo D.,Dongseo University
Advances in Intelligent Systems and Computing | Year: 2016

The permeable pavement is one of representative Low Impact Development (LID) facilities which were used to reduce flooding and recover the water cycle in urban environments. Since the unit cost of porous pavement is greater than that of non-porous pavement, the designs of permeable pavement need to consider reduction effect of rainwater runoff and cost of facilities. These are determined by the size and location of facilities. In this study, the optimal design of permeable pavement, considering the size and location of that, was simulated in a developed optimization model using the Harmony Search (HS)algorithm connected to the Storm Water Management Model (SWMM) to calculate urban Rainfall-Runoff. © Springer-Verlag Berlin Heidelberg 2016.

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