• International journal of steel structures
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• v.18 no.5
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• pp.1607-1616
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• 2018

Quantitatively modeling and propagating all sources of uncertainty stand at the core of seismic fragility assessment of structures. This paper investigates the effects of various sources of uncertainty on seismic responses and seismic fragility estimates of single-layer reticulated domes. Sensitivity analyses are performed to examine the sensitivity of typical seismic responses to uncertainties in structural modeling parameters, and the results suggest that the variability in structural damping, yielding strength, steel ultimate strain, dead load and snow load has significant effects on the seismic responses, and these five parameters should be taken as random variables in the seismic fragility assessment. Based on this, fragility estimates and fragility curves incorporating different levels of uncertainty are obtained on the basis of the results of incremental dynamic analyses on the corresponding set of 40 sample models generated by Latin Hypercube Sampling method. The comparisons of these fragility curves illustrate that, the inclusion of only ground motion uncertainty is inappropriate and inadequate, and the appropriate way is incorporating the variability in the five identified structural modeling parameters as well into the seismic fragility assessment of single-layer reticulated domes.

• Nuclear Engineering and Technology
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• v.49 no.2
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• pp.387-394
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• 2017

Seismic probabilistic risk assessment (SPRA) requires a large number of simulations to evaluate the seismic vulnerability of structural and nonstructural components in nuclear power plants. The effect of structural modeling and analysis assumptions on dynamic analysis of 3D and simplified 2D stick models of auxiliary buildings and the attached nonstructural components is investigated. Dynamic characteristics and seismic performance of building models are also evaluated, as well as the computational accuracy of the models. The presented results provide a better understanding of the dynamic behavior and seismic performance of auxiliary buildings. The results also help to quantify the impact of uncertainties associated with modeling and analysis of simplified numerical models of structural and nonstructural components subjected to seismic shaking on the predicted seismic failure probabilities of these systems.

• 한국연소학회:학술대회논문집
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• 2013.06a
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• pp.117-119
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• 2013

Combustion stability margin of a model gas turbine has been assessed by utilizing damping ratios of measured dynamic pressure data. It is known that acoustic oscillations in combustion chambers can be described as a superposition of nonlinearly interacting oscillators. Based on this theoretical background, CSMA (Combustion Stability Margin Assessment) code has been developed. The code has been employed into a model gas turbine combustion experiment, focused on the combustion instability, to show its capability to determine the damping ratio of measured dynamic pressure and further to assess combustion stability margin of the experiment, and turned out that the code works well.

• Proceedings of the Korea Concrete Institute Conference
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• 1996.10a
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• pp.486-491
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• 1996

The purpose of present study is to propose a improved damage detection and assessment algorithm that has its basis on the method of system identification. This method allows the use of composite data which is constitute of static displacements and eigenmodes. In the dynamic test, thecurvature and slope of mode shape are introduced to formulate the error responses. The effectiveness of the proposed staristical system identification method is investigated through simulated and experimental studies. Real test data obtained from measurements are used to identify the actual location of damage and to revise the design variables in a concrete structure.

• Korean Journal of Agricultural Science
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• v.43 no.3
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• pp.468-480
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• 2016

As the existing FTAs' implementations are being accelerated, ex-post assessments, such as tariff schedules and agricultural trade analyses results, have been emerging as important national issues for the agricultural sector. Korea-Chile FTA is the first FTA in Korea, and more than ten years have passed since April 2004. It will be necessary to measure the impacts of the agreement on the domestic agricultural industry by analyzing concessions made on traded items of farm products on prices, agricultural trade, and so on. The purpose of this study is to prepare for the request for ex-post assessments on the agricultural sector by trade negotiation procedural law. Additionally, by providing policy direction for agricultural policy segments requiring amendments and supplements through an ex-post assessment, we can more objectively evaluate the conflicting arguments between the agricultural and non-agricultural sectors. Current evaluation methods about ex-post impact assessment of FTA are generally comparison analysis on the change of trade balance before and after FTA implementation. However, this simple comparison analysis cannot be said to pure FTA effects and objective, tightening economic impact assessment of the FTA because of all combined situations such as effects of exchange rates, international macroeconomic changes, climate change, and the occurrence of pests. This research attempts to use dynamic analysis as its ex-post assessment methodology and is expected to contribute to future policy evaluation.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.35 no.5
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• pp.95-101
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• 2023

Recent persistent coastal developments have expanded recreational areas and enhanced accessibility. However, this growth has also led to a rise in safety incidents. These accident factors can be divided into human-made and natural types. The latter is comprised of dynamic factors like waves, tides, sea fogs, and winds. While institutions like the Korea Meteorological Administration and the Korea Hydrographic and Oceanographic Agency already offer data on these dynamic factors, the resolution is often insufficient for a precise assessment of localized risks. In this study, to overcome these limitations, we utilized the dynamic information from existing open systems to construct a high-resolution numerical simulation. Through this, we developed an automated module to predict dynamic factors in localized coastal activity areas. Particularly during the module's construction, we compared and reviewed the numerical prediction results for waves with observed wave heights.

• Journal of the Korean Society of Marine Environment & Safety
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• v.24 no.1
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• pp.36-42
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• 2018

This paper considers the Marine Traffic Risk Assessment for fixed and moving targets, which threaten officers during a voyage. The Collision Risk Assessment Formula was calculated based on a dynamic ship domain considering the length, speed and maneuvering capability of a vessel. In particular, the Navigation Risk Assessment Model that is used to quantitatively index the effect of a ship's size, speed, etc. has been reviewed and improved using a hybrid combination of a vessel's dynamic area and the Collision Risk Assessment Formula. Accordingly, a new type of Marine Traffic Risk Assessment Model has been suggested giving consideration to the Speed Length Ratio, which was not sufficiently reflected in the existing Risk Assessment Model. The larger the Speed Length Ratio (dimensionless speed), the higher the CJ value. That is, the CJ value is presented well by the Speed Length Ratio. When the Speed Length Ratio is large, states ranging from [Caution], [Warning], [Dangerous] or [Very Dangerous] are presented from a greater distance than when the Speed Length Ratio is small. The results of this study, can be used for route and port development, including dangerous route avoidance, optimum route planning, breakwater width, bridge span, etc. as well as the development of costal navigation safety charts. This research is also applicable for the selection of optimum ship routing and the prevention of collisions for smart ships such as autonomous vessels.

• Journal of the Korean Society of Hazard Mitigation
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• v.5 no.2 s.17
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• pp.29-35
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• 2005

In Korea more than ninety bridges are collapsed every year by flood, which causes the scour of pier foundation. Researches on the quantitative assessment method to assess the integrity of bridge against scour have not been organized systematically in the bridge design practice and maintenance area. In this study, dynamic characteristics assessment experiments are carried out as an emergency inspection method to assess the integrity of the pier foundation for scour after a flood. According to the dynamic characteristics assessment experiment, which simulates foundation scour of the spread footing pier, foundation scour can be evaluated by the first mode natural frequency of the pier.

• Steel and Composite Structures
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• v.35 no.2
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• pp.199-213
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• 2020

This paper proposes a Global-Local Analysis Method (GLAM) to assess the progressive collapse of steel framed structures under fire-induced column failure. GLAM obtains the overall structural response by combining dynamic analysis of the heated column (local) with static analysis of the overall structure (global). Test results of two steel frames which explicitly consider the dynamic effect during fire-induced column failure were employed to validate the proposed GLAM. Results show that GLAM gives reasonable predictions to the test frames in terms of both whether to collapse and the displacement verse temperature curves. Besides, several case studies of a two-dimensional (2D) steel frame and a three-dimensional (3D) steel frame with concrete slabs were conducted by using GLAM. Results show that GLAM gives the same collapse predictions to the studied cases with nonlinear dynamic analysis of the whole structure model. Compared with nonlinear dynamic analysis of the whole structure model, GLAM saves approximately 70% and 99% CPU time for the cases of 2D and 3D steel frame, respectively. Results also show that the load level of a structure has notable effects on the restraint condition of a heated column in the structure.

• Physical Therapy Rehabilitation Science
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• v.13 no.2
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• pp.240-249
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• 2024

Objective: The objective of this study is to evaluate various research that have examined dynamic knee valgus and to pinpoint a straightforward, clinically practical 2D assessment method for dynamic knee valgus that is user-friendly. Design: A literature review Methods: This literature review was conducted in Pubmed, MEDLINE^® and Google Scholar with the following key words: Knee valgus angle, Knee valgus evaluation, Knee valgus assessment, Dynamic knee valgus. After removing duplicate studies, 53 articles were initially chosen using this method, with 17 studies ultimately meeting the selection criteria. Results: Based on the comprehensive review of various studies, the Single Leg Squat (SLS) was identified as the most popular test method, followed by the Single Leg Landing (SLL) as the next most common test method. The Frontal Plane Projection Angle (FPPA) method was the most representative method for measuring dynamic knee valgus (DKV) during these tests. SLS was found in a total of 10 studies, while SLL was found in 7 studies. Conclusions: The most commonly proposed test for assessing DKV is measuring the SLS using the FPPA method. However, when applied to individuals without knee pathology, the discriminative power of this method may be limited. This suggests the need for further research to explore alternative methods for assessing DKV in this population.