• Structural Engineering and Mechanics
• /
• v.29 no.2
• /
• pp.135-154
• /
• 2008

The moving vehicle loads on a bridge deck is one of the most important live loads of bridges. They should be understood, monitored and controlled before the bridge design as well as when the bridge is open for traffic. A MOM-based algorithm (MOMA) is proposed for identifying the timevarying moving vehicle loads from the responses of bridge deck in this paper. It aims at an acceptable solution to the ill-conditioning problem that often exists in the inverse problem of moving force identification. The moving vehicle loads are described as a combination of whole basis functions, such as orthogonal Legendre polynomials or Fourier series, and further estimated by solving the new system equations developed with the basis functions. A number of responses have been combined, some numerical simulations on single axle, two axle and multiple-axle loads, being either constant or timevarying, have been carried out and compared with the existing time domain method (TDM) in this paper. The illustrated results show that the MOMA has higher identification accuracy and robust noise immunity as well as producing an acceptable solution to ill-conditioning cases to some extent when it is used to identify the moving force from bridge responses.

• Structural Engineering and Mechanics
• /
• v.29 no.2
• /
• pp.155-169
• /
• 2008

A MOM-based algorithm (MOMA) has been developed for moving force identification from dynamic responses of bridge in the companion paper. This paper further evaluates and investigates the properties of the developed MOMA by experiment in laboratory. A simply supported bridge model and a few vehicle models were designed and constructed in laboratory. A series of experiments have then been conducted for moving force identification. The bending moment and acceleration responses at several measurement stations of the bridge model are simultaneously measured when the model vehicle moves across the bridge deck at different speeds. In order to compare with the existing time domain method (TDM), the best method for moving force identification to date, a carefully comparative study scheme was planned and conducted, which includes considering the effect of a few main parameters, such as basis function terms, mode number involved in the identification calculation, measurement stations, executive CPU time, Nyquist fraction of digital filter, and two different solutions to the ill-posed system equation of moving force identification. It was observed that the MOMA has many good properties same as the TDM, but its CPU execution time is just less than one tenth of the TDM, which indicates an achievement in which the MOMA can be used directly for real-time analysis of moving force identification in field.

• Journal of the Society of Disaster Information
• /
• v.10 no.2
• /
• pp.244-252
• /
• 2014

In this study, seismic responses of the offshore wind tower supported by bucket foundation are analyzed in consideration of soil-structure interaction. The program SASSI is used as analyzing tool and an artificial seismic input for soft soil is used as input motion. The H/R ratio of bucket, the stiffness of bucket foundation and the soil stiffness are considered as parameters and its effects are estimated. The responses of structure are obtained at the base and the nacell. As results, the effects of H/R ratio, the stiffness of bucket and the stiffness of site are generally denoted different response tendency at the base and the nacell. However, these whole responses of the base and the nacell are much lager than that of rock site. Therefore, the consideration of this phemomia affect to the response of offshore wind tower with bucket foundation largely.

• Journal of the Korean Society of Safety
• /
• v.39 no.1
• /
• pp.62-69
• /
• 2024

Ensuring swift on-site access to fire engines is crucial in preserving the golden time and minimizing damage. However, various mobility constraints in alleyways hinder the timely entry of fire engines to the fire scene, significantly impairing their initial response capabilities. Therefore, this study analyzed the significant mobility constraints of fire engines, focusing on Seoul, which has many old town areas. By leveraging survey responses from firefighting experts and actual observations, this study quantitatively assessed the frequency and severity of mobility constraint factors affecting the disaster responses of fire engines. Survey results revealed a consistent set of top five factors regarding the frequency and disturbance level, including illegally parked cars, narrow paths, motorcycles, poles, and awnings/banners. A comparison with actual road-view images showed notable consistency between the survey and observational results regarding the appearance frequency of mobility constraint factors in vulnerable areas in Seoul. Furthermore, the study emphasized the importance of tailored management strategies for each mobility constraint factor, considering its characteristics, such as dynamic or static. The findings of this study can serve as foundational data for creating more detailed fire safety maps and advancing technologies that monitor the mobility of fire engines through efficient vision-based inference using CCTVs in the future.

• Journal of Korean Society for Geospatial Information Science
• /
• v.21 no.2
• /
• pp.71-83
• /
• 2013

Recently frequencies and scales in natural disasters have been significantly increased and enlarged and that leads to increase interests on preventing disasters. As natural disasters occur, it is difficult to fulfill the scale of natural disasters using ordinary stocks in a local government. Thus, it is necessary to establish a system that commonly uses protection resources according to regional characteristics in order to rapidly implement labor mobilization and equipment distribution based on the damage of natural disasters. In this study, regional characteristics in Korea provinces are analyzed and 'a way of composing a local government consortium for common disaster responses' is proposed. First, a disaster map that represents the amount of damage for each local government published in the disaster yearbook from 2002 to 2011 is produced using GIS. Then, the whole land is divided into five different sections according to administrative regions and that are divided into 12 clusters again based on the geographical and humanistic characteristics and the analysis of the scale of damage in typhoons and heavy rainfalls. Finally, disaster protection base stations for each region are selected. The data of analyzing disaster damages may be used as a reference material for establishing disaster prevention plans.

• Earthquakes and Structures
• /
• v.1 no.4
• /
• pp.411-425
• /
• 2010

The effect of dead loads on dynamic responses of uniform elastic beams is examined by means of a governing equation which takes into account initial bending stress due to dead loads. First, the governing equation of beams which includes the effect of dead loads is briefly presented from the author's paper (Takabatake 1990). In the formulation the effect of dead loads is considered by strain energy produced by conservative initial stresses produced by the dead loads. Second, the effect of dead loads on dynamical responses produced by live loads in simply supported beams and clamped beams is confirmed by the results of numerical computations with the Galerkin method and Wilson-${\theta}$ method. It is shown that the dynamical responses, like dynamic deflections and bending moments produced by dynamic live loads, are decreased in a heavyweight beam when the effect of dead loads is included. Third, an approximate solution for dynamic deflections including the effect of dead loads is presented in closed-form. The proposed solution shows good in agreement with results of numerical computations with the Galerkin method and Wilson-${\theta}$ method. Finally, a method reflecting the effect of dead loads for dynamic responses of beams on the magnitude of live loads is presented by an example.

• Structural Engineering and Mechanics
• /
• v.56 no.6
• /
• pp.1021-1040
• /
• 2015

An effective method to calculate aerodynamic loads and aeroelastic responses of large wind turbine tower-blade coupled structures in yaw condition is proposed. By a case study on a 5 MW large wind turbine, the finite element model of the wind turbine tower-blade coupled structure is established to obtain the modal information. The harmonic superposition method and modified blade-element momentum theory are used to calculate aerodynamic loads in yaw condition, in which the wind shear, tower shadow, tower-blade modal and aerodynamic interactions, and rotational effects are fully taken into account. The mode superposition method is used to calculate kinetic equation of wind turbine tower-blade coupled structure in time domain. The induced velocity and dynamic loads are updated through iterative loop, and the aeroelastic responses of large wind turbine tower-blade coupled system are then obtained. For completeness, the yaw effect and aeroelastic effect on aerodynamic loads and wind-induced responses are discussed in detail based on the calculating results.

• Journal of Korean Society of Disaster and Security
• /
• v.12 no.3
• /
• pp.25-34
• /
• 2019

Modern disasters prevent accidents in advance and recover after accidents are very important. Our government's current response to these accidents is not appropriate. As for disaster management so far, it has been the center of disaster response and recovery efforts, and has been led by the government against it. The reality is that most private organizations and agencies have only subsidized government disaster management agencies. Korea is no longer a safe zone for earthquakes. Now for the establishment of effective disaster management system for earthquakes in the diagnosis is very urgent and the problems of the operational disaster management, which the problems of the nation.Policies to improve academic efforts to seek alternative proposal is also at a time when volume can be said to be very big need to mine. This study from 2016 to 2019, about the earthquake that took place between National Statistical Office, based on analysis of data to. First of all, research 1: What was the government's plan on Pohang earthquake? The results showed that the residents' evacuation of Pohang was important in the Pohang earthquake, but for the sake of students' safety, they were directly assigned to the test site to cope with the emergency situation. Therefore, the research and analysis shows that the nation should continue to think about the causes and responses of the damage at the disaster site and strive to develop technologies and methods to minimize the damage.

• Journal of Digital Contents Society
• /
• v.19 no.4
• /
• pp.673-683
• /
• 2018

The accident of Sewol Ferry is a disaster that provoked serious mental shock to the Korean people way beyond the level of generally-perceived catastrophic aftermaths. The purpose of this study is to examine the relationship between vicarious disaster experiences through media and post-traumatic stress(PTSD) symptoms of media users related to the accident. The responses of 417 people consisted of college, middle and high school students, and adults in a metropolitan area were collected for 12 days from the April 28, 2014 right after the accident. The results showed that the level of PTSD of social media users were higher than that of traditional media (newspapers or TV news) users on the accident. Also, the amount of use of disaster news information and social media revealed positive correlations with PTSD. Implications of this study are to demonstrate possible mechanisms of psychological trauma mediated by media on a disaster and its empirical data and to facilitate further research.

• Fire Science and Engineering
• /
• v.29 no.5
• /
• pp.73-78
• /
• 2015

Since the hydrofluoric acid spill accident in Gumi in 2012, the current situation has continued to suffer from makeshift responses or feeble national system maintenance in preparing real countermeasures against chemical accidents, regardless of their repeated occurrence and seriousness. Industrial chemical accidents have an enormous ripple effect on the whole country and society. The purpose of this study is to propose ways of establishing directions for the national disaster management system against repeated occurrence of chemical accidents. To achieve this goal, the present study proposed improvement measures of response system for industrial chemical accident through the analysis of the current response system and structural causes of disaster control failure for chemical accidents.