• Proceedings of the Korean Geotechical Society Conference
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• 2009.09a
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• pp.863-874
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• 2009

The engineering characteristics and the reinforcement effect of the elephant foot method were discussed with parametric study. The elephant foot method is adopted to support the loads transferred from tunnel crown and improve bearing capacity of elephant foot in poor ground condition. The evaluation of reinforcement effect, which has the mechanical relationship between ground condition, footing size and reinforcement system, was carried out through the previous research and numerical analysis. In addition, the simple design chart was proposed to estimate the applicability of the elephant foot reinforcement method. It will be practical for the engineer to determine the optimum reinforcement method for safe tunnelling in soft ground condition.

• International Journal of High-Rise Buildings
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• v.7 no.2
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• pp.161-170
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• 2018

Rapid urbanization, resource depletion, and limited land are further increasing the need for skyscrapers in city centers; therefore, it is imperative to enhance tall building performance efficiency and energy-generative capability. Potential performance improvements can be explored using parametric multi-objective optimization, aided by evaluation tools, such as computational fluid dynamics and energy analysis software, to visualize and explore skyscrapers' multi-resource, multi-system generative potential. An optimization-centered, software-based design platform can potentially enable the simultaneous exploration of multiple strategies for the decreased consumption and large-scale production of multiple resources. Resource Generative Skyscrapers (RGS) are proposed as a possible solution to further explore and optimize the generative potentials of skyscrapers. RGS can be optimized with waste-energy-harvesting capabilities by capitalizing on passive features of integrated renewable systems. This paper describes various resource-generation technologies suitable for a synergetic integration within the RGS typology, and the software tools that can facilitate exploration of their optimal use.

• Journal of Korean Society of Steel Construction
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• v.25 no.3
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• pp.223-231
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• 2013

Recently, high-performance steels have been increasingly used for structural materials in buildings and bridges with the demand for high-rise and long-span of main structures. This paper offers a series of basic study for the design specification of structural members using high performance steel, that is material properties of HSA800 (High-performance rolled steel for building structures). Built-up square tube stub columns with variables of width-to-thickness ratios are planned as a parametric study in order to investigate the local buckling behaviors and check the current design limit of width-to-thickness ratio. In addition, the buckling behaviors of stub columns obtained finite element (FE) analysis were compared with those from experimental tests. The verified FE model was used for parametric study and checked applicability of high-strength steel on current design specification.

• Journal of the Earthquake Engineering Society of Korea
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• v.10 no.6 s.52
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• pp.47-56
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• 2006

A method is presented for evaluating the economic efficiency of a semi-active magneto-rheological (MR) damper system for cable-stayed bridges under earthquake loadings. An optimal MR damper capacity maximizing the cost-effectiveness is estimated for various seismic characteristics of ground motion. The economic efficiency of MR damper system is addressed by introducing the life-cycle cost concept. To evaluate the expected damage cost, the probability of failure is estimated. The cost-effectiveness index is defined as the ratio of the sums of the expected damage costs and each device cost between a bridge structure with the MR damper system and a bridge structure with elastic bearings. In the evaluation of cost-effectiveness, the scale of damage cost is adopted as parametric variables. The results of the evaluation show that the MR damper system can be a cost-effective design alternative. The optical capacity of MR damper is increased as the seismic hazard becomes severe.

• Journal of Mechanical Science and Technology
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• v.20 no.12
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• pp.2061-2078
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• 2006

The main purpose of this paper is to establish the high temperature structural integrity evaluating procedures for the next generation reactors, which are to be operated at over 500$^{\circ}C$ and for 60 years. To do this, comparison studies of the high temperature structural design codes and assessment procedures such as the ASME-NH (USA), RCC-MR (France), DDS (Japan), and R5 (UK) are carried out in view of the accumulated inelastic strain and the creep-fatigue damage evaluations. Also the application procedures of the ASME-NH rules with the actual thermal and structural analysis results are described in detail. To overcome the complexity and the engineering costs arising from a real application of the ASME-NH rules by hand, all the procedures established in this study such as the time-dependent primary stress limits, total accumulated creep ratcheting strain limits, and the creep-fatigue damage limits are computerized and implemented into the SIE ASME-NH program. Using this program, the selected high temperature structures subjected to two cycle types are evaluated and the parametric studies for the effects of the time step size, primary load, number of cycles, normal temperature for the creep damage evaluations and the effects of the load history on the creep ratcheting strain calculations are investigated.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2006.04a
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• pp.1001-1008
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• 2006

The main objective of this paper is to compare economical effectiveness of typical methods for checking stability in principal components of steel cable-stayed bridges. Elastic and inelastic buckling analyses are carried out for frame-like numerical models of cable-stayed bridges. The axial-flexural interaction equations prescribed in AASHTO Allowable Stress Design (ASD) and AASHTO Load and Resistance Factor Design (LRFD) are used in order to check the stability of principal components. Parametric studies are performed for numerical models which have the center span length of 300m, 600m, 900m and l200m with different girder depths. Peak values of the interaction equations are calculated at the intersection point between girders and towers. These peak values are considered as a major factor to design of principal components of cable-stayed bridges. As a result, more economical design for girders and towers can be feasible using the inelastic buckling analysis. In addition, LRFD codes are more economical about 20% on the average than ASD codes for all numerical models of cable-stayed bridges.

• KIEAE Journal
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• v.5 no.3
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• pp.3-9
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• 2005

Venetian blinds are used with windows to improve the uniformity ratio of illuminance and interior daylighting distribution under direct sunlit conditions. The main objective of Venetian blinds shading system is to obstruct direct sunlight and at the same time allow daylight to penetrate into the room. Venetian blinds would have greater effect on the interior daylighting condition under clear sky which has both skylight and sunlight than overcast sky which has only skylight. However, due to the lack of data, design and evaluation tools, it is difficult for architects to choose or install venetian blinds during the building design stages. The purpose of this study was to develop an analysis method for shading and daylighting effects of Venetian blinds using the RADIANCE program. The major variables related to the venetian blinds included blinds's slat angle and the ratio of slat width to window height, the radius slat of curvature and the building azimuth. In this study, a series of parametric physical mock-up model measurements and genblinds command in the RADIANCE simulations. The results of this study will provide building designers with the design data at early design stages.

• Korean Parent-Child Health Journal
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• v.14 no.1
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• pp.1-8
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• 2011

Purpose: This study was aimed to classify the major subjects and theme and to analyze the data collection and analysis method in research papers published in the Korean Parent-Child Health Journal of the Academic Society of Parent-Child Health since 1998. Methods: A total 152 studies published from the first edition to volume 12, number 2 were reviewed using structured analysis criteria developed by researchers; research type, research design, research subjects, research theme, data collection and analysis method. Research theme was founded 4 nursing domains. Data collection and analysis method of papers were limited to quantitative and qualitative researches. Results: One hundred papers conducted quantitative research; 79.0% used survey design. Most of the data collection and analysis method in quantitative research were self-reported questionnaire (69.4%) and parametric statistics respectively. The research subjects of sixty three papers were parent with well or child. The common domain studies was human related concepts such as raring. Conclusion: The findings of this study suggest that published studies have been improved and diversified, however, detailed and clear evaluation tool that assess study process and method should be developed as a way to further improve the quality of published papers in the Korean Parent-Child Health Journal.

• Steel and Composite Structures
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• v.32 no.3
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• pp.347-359
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• 2019

Modular construction has been increasingly used for mid-to-high rise buildings attributable to the high construction speed, improved quality and low environmental pollution. The individual and repetitive room-sized module unit is usually fully finished in the factory and installed on-site to constitute an integrated construction. However, there is a lack of design guidance on modular structures. This paper mainly focuses on the evaluation of the initial stiffness of corrugated steel plate shears walls (CSPSWs) in container-like modular construction. A finite element model was firstly developed and verified against the existing cyclic tests. The theoretical formulas predicting the initial stiffness of CSPSWs were then derived. The accuracy of the theoretical formulas was verified by the related numerical and test results. Furthermore, parametric analysis was conducted and the influence of the geometrical parameters on the initial stiffness of CSPSWs was discussed and evaluated in detail. The present study provides practical design formulas and recommendations for CSPSWs in modular construction, which are useful to broaden the application of modular construction in high-rise buildings and seismic area.

• Structural Engineering and Mechanics
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• v.84 no.5
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• pp.651-664
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• 2022

A precise prediction of the ultimate bond strength between rebar and surrounding concrete plays a major role in structural design, as it effects the load-carrying capacity and serviceability of a member significantly. In the present study, Gaussian models are employed for modelling bond strength of ribbed steel bars embedded in concrete. Gaussian models offer a non-parametric method based on Bayesian framework which is powerful, versatile, robust and accurate. Five different Gaussian models are explored in this paper-Gaussian Process (GP), Variational Heteroscedastic Gaussian Process (VHGP), Warped Gaussian Process (WGP), Sparse Spectrum Gaussian Process (SSGP), and Twin Gaussian Process (TGP). The effectiveness of the models is also evaluated in comparison to the numerous design formulae provided by the codes. The predictions from the Gaussian models are found to be closer to the experiments than those predicted using the design equations provided in various codes. The sensitivity of the models to various parameters, input feature space and sampling is also presented. It is found that GP, VHGP and SSGP are effective in prediction of the bond strength. For large data set, GP, VHGP, WGP and TGP can be computationally expensive. In such cases, SSGP can be utilized.