• Proceedings of the Computational Structural Engineering Institute Conference
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• 1996.04a
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• pp.202-211
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• 1996

A number of typical type of steel-box pedestrian bridges are constructed in the metropolitan highway or heavy traffic urban area. Although it has the advantage of speedy construction because of its simple structural form and prefabricated erection method, it has been reported that many of these bridges are deteriorated or damaged and thus are in the state such that it would give unsafe and uncomfortable feeling to pedestrians. In the paper, for the realistic assessment of safety and residual earring-capacity of deteriorated and/or damaged steel box pedestrian bridges, an interactive non-linear limit state model are formulated based on the von Mises' combined stress yield criterion. It is demonstrated that the proposal model is effective for the reliability-based safety assessment and residual carrying-capacity evaluation of steel-box pedestrian bridges. In addition, this study suggests an effective and practical field load test method for pedestrian bridges.

• Structural Engineering and Mechanics
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• v.29 no.5
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• pp.531-550
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• 2008

This paper adopts the numerical assembly method (NAM) to determine the exact solutions of natural frequencies and mode shapes of a multi-span and multi-step beam carrying a number of various concentrated elements including point masses, rotary inertias, linear springs, rotational springs and springmass systems. First, the coefficient matrix for an intermediate station with various concentrated elements, cross-section change and/or pinned support and the ones for the left-end and right-end supports of a beam are derived. Next, the overall coefficient matrix for the entire beam is obtained using the numerical assembly technique of the conventional finite element method (FEM). Finally, the exact solutions for the natural frequencies of the vibrating system are determined by equating the determinant of the last overall coefficient matrix to zero and the associated mode shapes are obtained by substituting the corresponding values of integration constants into the associated eigenfunctions.

• Journal of the Korea Institute of Building Construction
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• v.6 no.4 s.22
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• pp.45-52
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• 2006

Top Down method is more widely used in downtown construction, recently. As underground construction constitutes a significant portion of the total construction cost and time in Top Down construction, it is important to develop a construction method to reduce the time required in underground works. The purpose of this study is to analyze load carrying capacity of Top Down prefounded columns on different excavation schedule. When several floors are excavated, the valid buckling length of prefounded column is increased and allowable buckling stress is decreased. The result shows that all columns are safe in buckling down to B3 story whether 2 or 3 stories are excavated. However, several columns are not safe from B4 story when 2 or 3 stories are excavated straightly. With these results, a process can be designed that the first three stories in the basement are excavated, and then excavate B4 story after placing concrete on B1 and B2 floor.

• Journal of Korean Institute of Industrial Engineers
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• v.42 no.3
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• pp.165-172
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• 2016

The purpose of this study is to investigate the ergonomic verification of suitability of the 4-wheeled hand cart to prevent musculoskeletal problems in the firing test range. Because of the increasing amount of firing test, the needs to develop a projectile transferring device such as 4-wheeled hand cart has been increased. For the 4-wheeled hand cart, the lifting and carrying activity in the manual handling method were transformed to pushing activity. The risk of low back pain for lifting and carrying the projectile by manual was estimated by NLE and 3D SSPP. On the other hand, the risk for pushing the 4-wheeled hand cart was estimated by psychophysical and biomechanical method such as Mital's equation, Snook's table and 3D SSPP. It was shown that the 4-wheeled hand cart reduced the risk of low back pain drastically with higher efficiency and design compatibility.

• Journal of the Korean Solar Energy Society
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• v.39 no.4
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• pp.79-91
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• 2019

The capacity credit (CC) is a key metric for mid- to long-term power system capacity planning. The purpose of this study is to estimate the CCs of domestic wind turbines. Based on hourly capacity factor (CF) data during the seven years from 2011 to 2017, the new so-called probabilistic CF scheme is introduced to effectively reflect the variability of CFs on CC estimation. The CCs are then estimated through the CF-based method and the ELCC (Effective Load Carrying Capability) method reflecting the probabilistic CF scheme, and the results are compared. The results show that the CC value 0.019 for domestic wind turbines proposed in the $8^{th}$ Basic Plan for Electricity Supply and Demand corresponds to the CC with a confidence level slightly lower than 95%.

• International conference on construction engineering and project management
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• 2009.05a
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• pp.1618-1624
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• 2009

Since various methods for repairing and rehabilitating have been applied to damaged bridges to increase their load carrying capacity, many researches on the methods have been widely carried out. In particular, In terms of applicability, strengthening efficiency and economical efficiency, external tendons using lifting hole anchorage system is the most effective method among the aforementioned methods. In order to verify the strengthening effectiveness, flexural experiments on the beams strengthened with external tendons using lifting hole anchorage system were carried out. The experiments were conducted on two groups of systems, the existing and the proposed external tendons using lifting hole anchorage system. In addition, An evaluation on ductility of the beams were conducted in this paper.

• Natural Product Sciences
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• v.9 no.4
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• pp.299-303
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• 2003

For the screening of inhibitors of sterol biosynthesis from natural products, a simple and rapid assay method was developed using recombinant yeast carrying human lanosterol synthase, main target of this assay method. Sterol biosynthesis inhibition activity was monitored only by the inhibition of growth of the recombinant yeast. By changing the substrate, this assay method can figure out which step is inhibited in the sterol biosynthesis by the test material. With this assay method total 102 plant samples were screened for their inhibitory activity of sterol biosynthesis. Among plant water extracts screened, 11 plant samples showed inhibitory activity on sterol biosynthesis in ergosterol (-) medium. For selection of the specific inhibitory materials, 11 plant samples were reassayed in ergosterol (+) medium. After all 5 plant samples, Abutilon avicennae Gaertn. (stem), Alnus japonica Steud. (stem), Amaranthus mangostanus L. (aerial part), Philadelphus schrenckii Pupr. (leaf) and Pimpinelia brachycarpa Nakai (aerial part), showed specific inhibitory activity.

• Journal of Institute of Control, Robotics and Systems
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• v.7 no.3
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• pp.198-208
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• 2001

In this paper, vibration suppression of an elastic beam fixed on a moving cart and carrying a fixed or moving mass is considered. A modified pulse sequence method with RIC(Robust Internal-loop Compensator) is proposed to suppress the single model residual vibration and to get accurate positioning of the beam-mass-cart system. The performance of the proposed input preshaping method is compared with that of the previous ones through simulations and experiments. Using the proposed method, it is able to suppress the initial vibration of the beam-mass-cart system carrying a concentrated mass. Accurate PTP(point-to-point) positioning of the moving mass without residual vibration is also obtained experimentally by modifying the proposed pulse sequence method. Finally, the proposed input preshaping method is applied successfully to the system to follow square trajectories of the moving mass without residual vibration.

• Structural Engineering and Mechanics
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• v.34 no.2
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• pp.247-275
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• 2010

In this study, experimental, numerical, and analytical approaches were carried out to evaluate the behavior and prestressing effect of prestressed composite beam by external tendon and cover plate. Behavior of prestressed composite beam, load-carrying capacity, effects of prestressing, and ultimate strength were estimated. The contribution of the section increase of the prestressing method using tendon was less than the prestressing method using cover plate. In accordance with numerical and analytical approaches, the ultimate strength of the prestressed composite beam is shown to be the same value because strength is determined according to the plastic resistance moment and the plastic neutral axis; however, both plastic resistance moment and neutral axis are not affected by prestressing force but affected by sectional stiffness of the prestressing member. Based on these approaches, we concluded that the prestressing method using tendon can be useful in applications without an increase in self-weight, and the prestressing method using high-strength cover plate can be applied to reduce the deflection of the composite beam. The prestressing method using high-strength cover plate can also be used to induce prestress of the composite beam in the case of a large deflection due to a smaller sectional stiffness of the composite beam.

• Structural Engineering and Mechanics
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• v.14 no.3
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• pp.331-343
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• 2002

Because of the increasing span of arch bridges, ultimate capacity analysis recently becomes more focused both on design and construction. This paper investigates the static and ultimate behavior of a long-span steel arch bridge up to failure and evaluates the overall safety of the bridge. The example bridge is a long-span steel arch bridge with a 550 m-long central span under construction in Shanghai, China. This will be the longest central span of any arch bridge in the world. Ultimate behavior of the example bridge is investigated using three methods. Comparisons of the accuracy and reliability of the three methods are given. The effects of material nonlinearity of individual bridge element and distribution pattern of live load and initial lateral deflection of main arch ribs as well as yield stresses of material and changes of temperature on the ultimate load-carrying capacity of the bridge have been studied. The results show that the distribution pattern of live load and yield stresses of material have important effects on bridge behavior. The critical load analyses based on the linear buckling method and geometrically nonlinear buckling method considerably overestimate the load-carrying capacity of the bridge. The ultimate load-carrying capacity analysis and overall safety evaluation of a long-span steel arch bridge should be based on the geometrically and materially nonlinear buckling method. Finally, the in-plane failure mechanism of long-span steel arch bridges is explained by tracing the spread of plastic zones.