• Geomechanics and Engineering
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• v.33 no.4
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• pp.415-425
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• 2023

Pile-supported wharves, port structures that support the upper deck, are installed on sloping ground. The sloping ground should be covered with a rubble mound or artificial blocks to protect the interior material from erosion caused by wave force. The behavior of the pile may vary during an earthquake if a rubble mound is installed on the slope. However, studies evaluating the effect of rubble mound on the pile during an earthquake are limited. Here, we performed dynamic centrifuge model tests to evaluate the dynamic behavior of piles installed in a slope reinforced with rubble mound. In the structure, some sections (single-pile, 2×2 group-pile) were selected for the experiment. The moment of the group-pile decreased by up to 26% upon installation of the rubble mound, whereas the moment of the single-pile increased by up to 41%, thus demonstrating conflicting results.

• International Journal of Advanced Culture Technology
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• v.12 no.1
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• pp.16-19
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• 2024

One of the current focal points in the defense sector is how to strategically leverage the technologies of the Fourth Industrial Revolution in military operations. The Fourth Industrial Revolution denotes a transformational shift in the environment where automation and connectivity are maximized, primarily driven by advancements in machine learning and artificial intelligence. Coined by Klaus Schwab at the 2015 Davos Forum, this term signifies a profound change in human activities, akin to how a single machine replaced hundreds of laborers in the past. The military application of Fourth Industrial Revolution technologies is increasingly researched and anticipated to be actively implemented. Combat, as a subset of warfare, entails military actions between units conducting war. Typically performed by units to achieve one or more objectives, the concept of combat involves the fundamental ideas guiding the conduct of military operations against adversaries, both presently and in the future. Hence, it is imperative for our military to develop future combat concepts by harnessing the key technologies of the Fourth Industrial Revolution.

• Earthquakes and Structures
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• v.3 no.2
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• pp.169-180
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• 2012

The performance of pure friction isolation system with respect to the frequency bandwidth of excitation and the predominant frequency is investigated. A set of earthquake ground motions (artificial as well as recorded [with different combinations of magnitude-distance and local site geology]) is considered for investigating effectiveness of pure friction isolators. The results indicate the performance of pure friction base isolated system does not only depend upon coefficient of friction and mass ratio but the stick-slip behaviour depends upon the frequency content of the excitation as well. Slippage prevails if the excitation frequency lies in a suitable frequency range. This range widens with increasing mass ratio. For larger mass ratios, the sliding effect is more pronounced and the maximum acceleration response is further reduced in the neighbourhood of frequency ratio (${\omega}/{\omega}_n$) of unity. The pure friction isolation system is effective in the case of broadband excitations only and that too, in the acceleration sensitive range of periods. The pure friction system is not effective for protection against narrow band motions for which the system response is quasi-periodic.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.11a
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• pp.459-464
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• 2007

Seismic control performance of MR dampers, which have severe nonlinearity, differs with respect to the dynamic characteristics of an earthquake such as magnitude, frequency and duration. In this study, the effects of excitation characteristics on the equivalent linear system of a building structure with the MR damper are investigated through numerical analysis for artificial ground motions generated from different response spectrums. The equivalent damping ratio of the structure with the MR damper is calculated using Newmark and Hall's equations for ground motion amplification factors. It is found that the equivalent damping ratio of the structure with the MR damper is dependent on the ratio of the maximum friction force of the MR damper over excitation magnitude. Frequency contents of the earthquake ground motion affects the equivalent damping ratio of long-period structures considerably. Also, additional damping effect caused by interaction between the viscousity and friction of the MR damper is observed. Finally, response reduction factors for equivalent linear systems are proposed in order to improve accuracy in the prediction of the actual nonlinear response.

• Earthquakes and Structures
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• v.15 no.3
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• pp.295-306
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• 2018

Reinforced concrete containment (RCC) building has long been considered as the last barrier for keeping the radiation from leaking into the environment. It is important to quantify the performance of these structures and facilities considering extreme conditions. However, the preceding research on evaluating nuclear power plant (NPP) structures, particularly considering mainshock-aftershock seismic sequences, is deficient. Therefore, this manuscript serves to investigate the seismic fragility of a typical RCC building subjected to mainshock-aftershock seismic sequences. The implementation of the fragility assessment has been performed based on the incremental dynamic analysis (IDA) method. A lumped mass RCC model considering the tri-linear skeleton curve and the maximum point-oriented hysteretic rule is employed for IDA analyses. The results indicate that the seismic capacity of the RCC building would be overestimated without taking into account the mainshock-aftershock effects. It is also found that the seismic capacity of the RCC building decreases with the increase of the relative intensity of aftershock ground motions to mainshock ground motions. In addition, the effects of artificial mainshock-aftershock ground motions generated from the repeated and randomized approaches and the polarity of the aftershock with respect to the mainshock on the evaluation of the RCC are also researched, respectively.

• KIEAE Journal
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• v.7 no.4
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• pp.9-15
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• 2007

As environmental problems and water-shortage phenomenon become a global issue, many states look for the effective method to use water resources. So, decentralized rainwater management is recognized as a new water management system that rainwater can be infiltrated and used on-site. But it is little difficult to build a park, lake, and forest for evaporating rainwater in city because the land price of city is very high. In order to build an excellent infiltration system for a dwelling and a park in Korea, KICT has developed Linear infiltration system. This infiltration system is consist of first flush treatment, storage and infiltration, overflow control system. These elements are connected closely and working as a combined system. A storm sewer can be changed by the linear infiltration system. This study is to show real application idea about Linear infiltration system with improving some detail in apartments. For this purpose, we devide application idea into the artificial ground and the natural ground and each ground type, suggest a method to cooperate with the other landscape and linear infiltration system. Through this study, we came to recognize a recognition difference of an expert and a commoner about decentralized rainwater management.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.13 no.2
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• pp.211-218
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• 1993

Landslides, failure of slope stability by natural or artificial factors, occur loss of life and properties. Recently, statistical methods and field measurements are used to a study for prediction of landslide harzard area, but there are so many difficulties to find the occurence system because of its complexity. In this study, authors choose the model area where occured landslides to predict the landslide hazard. Authors made a database of ground height to compare the each topography by scale of 1 : 25,000, 1 : 10,000, 1 : 5,000 and 1 : 1,200. Authors predict to landslide hazard area by the weight of ground height data and slope angle data. Finally, authors could know the possibility of prediction to find the landslide hazard partly.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.23 no.6
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• pp.451-457
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• 2011

Large scale fishing ground can be made by upwelling flow. Recently the fishing ground development projects, using artificial upwelling by large structure under the sea, are in progress in Japan and Korea. In this study upwelling flow is simulated with FLOW-3D model. Using the movement of marker in FLOW-3D, the method for simulating upwelling of nutrients was experimented. The results show that FLOW-3D model can evaluate upwelling effect before starting real project.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.05a
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• pp.879-885
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• 2006

Seismic control performance of MR dampers, which have severe nonlinearity, differs with respect to the dynamic characteristics of an earthquake such as magnitude, frequency and duration. In this study, the effects of excitation characteristics on the equivalent linear system of a building structure with the MR damper are investigated through numerical analysis for artificial ground motions generated from different response spectrums. The equivalent damping ratio of the structure with the MR damper is calculated using Newmark and Hall's equations for ground motion amplification factors. It is found that the equivalent damping ratio of the structure with the MR damper is dependent on the ratio of the maximum friction force of the MR damper over excitation magnitude. frequency contents of the earthquake ground motion affects the equivalent damping ratio of long-period structures considerably. Also, additional damping effect caused by interaction between the viscousity and friction of the MR damper is observed. Finally, response reduction factors for equivalent linear systems are proposed in order to improve accuracy in the prediction of the actual nonlinear response.

• KIEAE Journal
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• v.14 no.3
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• pp.65-70
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• 2014

The thermal environment in a small city rapidly deteriorates due to the urbanization and overpopulation. It is important to understand and predict the thermal environment in a city area. The thermal environment is highly affected by the solar radiation and temperature distributions changing over time periodically. To predict the thermal environment precisely, the solar radiation calculation including radiation strength, incidence angle, and thermal radiation between building surface and ground should be considered. In this study, the computational domain includes various artificial structures such as building, ground, asphalt, brick and grass. To consider the solar radiation, the unsteady state numerical calculation is performed from sun rise to mid-day (2:00pm). The numerical methods consist of solar load and one dimensional heat conduction through the boundaries to reduce the computational load and improve the flexibility of the calculation.