• Journal of Korea Water Resources Association
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• v.51 no.8
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• pp.703-711
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• 2018

Water distribution system (WDS) pipe bursts are caused from excessive pressure, pipe aging, and ground shift from temperature change and earthquake. Prompt detection of and response to the failure event help prevent large-scale service interruption and catastrophic sinkhole generation. To that end, this study proposes a improved Western Electric Company (WECO) method to improve the detection effectiveness and efficiency of the original WECO method. The original WECO method is an univariate Statistical Process Control (SPC) technique used for identifying any non-random patterns in system output data. The improved WECO method multiples a threshold modifier (w) to each threshold of WECO sub-rules in order to control the sensitivity of anomaly detection in a water distribution network of interest. The Austin network was used to demonstrated the proposed method in which normal random and abnormal pipe flow data were generated. The best w value was identified from a sensitivity analysis, and the impact of measurement frequency (dt = 5, 10, 15 min etc.) was also investigated. The proposed method was compared to the original WECO method with respect to detection probability, false alarm rate, and averaged detection time. Finally, this study provides a set of guidelines on the use of the WECO method for real-life WDS pipe burst detection.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.26 no.1
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• pp.59-67
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• 2013

Complex-shaped tall building causes many structural challenges due to its structural characteristics regarding inclined members and complexed shape. This paper is aimed at development of design process using computational-platform which is effective design tool for responding frequent design changes, particularly as to overseas projects. StrAuto, a parametric structural modeling and optimizing system, provides the optimized alternatives according to design intent and realize a swift process converting a series of structural information necessary to nonlinear analytical models. The application of the process was to a 45-story hotel building in Ulanbator, Mongolia adopting shear wall and special moment frame with outrigger systems. To investigate the safety of lateral force resisting system against maximum considered earthquake(MCE), nonlinear response history analysis was conducted using StrAuto.

• Journal of the Korean Geotechnical Society
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• v.32 no.9
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• pp.51-62
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• 2016

Parametric studies for various site conditions by using 3d numerical model were carried out in order to estimate dynamic behavior of soil-pile-structure system in dry soil deposits. Proposed model was analyzed in time domain using FLAC3D which is commercial finite difference code to properly simulate nonlinear response of soil under strong earthquake. Mohr-Coulomb criterion was adopted as soil constitutive model. Soil nonlinearity was considered by adopting the hysteretic damping model, and an interface model which can simulate separation and slip between soil and pile was adopted. Simplified continuum modeling was used as boundary condition to reduce analysis time. Also, initial shear modulus and yield depth were appropriately determined for accurate simulation of system's nonlinear behavior. Parametric study was performed by varying weight of superstructure, pile length, pile head fixity, soil relative density with proposed numerical model. From the results of parametric study, it is identified that inertial force induced by superstructure is dominant on dynamic behavior of soil-pile-structure system and effect of kinematic force induced by soil movement was relatively small. Difference in dynamic behavior according to the pile length and pile head fixity was also numerically investigated.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.4
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• pp.69-75
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• 2019

The frequency of natural disasters and the scale of damage are increasing due to the abnormal weather phenomenon that occurs worldwide. Especially, damage caused by natural disasters in coastal areas around the world such as Earthquake in Japan, Hurricane Katrina in the United States, and Typhoon Maemi in Korea are huge. If we can predict the damage scale in response to disasters, we can respond quickly and reduce damage. In this study, we developed damage prediction functions for Wind waves caused by sea breezes and waves during various natural disasters. The disaster report (1991 ~ 2017) has collected the history of storm and typhoon damage in coastal areas in Korea, and the amount of damage has been converted as of 2017 to reflect inflation. In addition, data on marine weather factors were collected in the event of storm and typhoon damage. Regression analysis was performed through collected data, Finally, predictive function of the sea turbulent damage by the sea area in 74 regions of the country were developed. It is deemed that preliminary damage prediction can be possible through the wind damage prediction function developed and is expected to be utilized to improve laws and systems related to disaster statistics.

• The Journal of the Petrological Society of Korea
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• v.21 no.1
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• pp.1-12
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• 2012

The Baegdusan volcano is one of the most active volcanoes in northeastern Asia, and the 10th century eruption was the most voluminous eruption in the world in recent 2,000 years. During the period from 2002 to 2005, volcanic earthquakes and abnormal surface distortions by suspected subsurface magma intrusion beneath the volcano were observed in the Baegdusan area. Seismic activity has gradually increased with earthquake swarms during 2002-2003 and hundreds of seismic event in a day, especially annual peak of 2,100 in 2003. Then the number of seismic activity has declined since 2006 to the background level in 1999-2001. According to the typical frequency of volcanic earthquakes in the Baegdusan volcano, the frequency distribution of typical volcanic earthquakes between 2002 and 2005 indicates that all the main frequency of the earthquakes basically falls down less than 5 Hz and 5-10 Hz. These events are all the VT-B and LP events caused by the shallow localized fracture and intrusion of magma. The horizontal displacement measurement by GPS during the period from 2000 to 2007 of the Baegdusan stratovolcano area indicates that an inflated process has been centered at the summit caldera since 2002. The displacement between 2002 and 2003 reached at a maximum value of 4 cm. After 2003, the deformation rate of the volcano continued to decrease with unusual variation during the period from 2006 to 2007. After 2003 the vertical displacement uplift rate falls down gradually but still keeps in an uplift trend in northern slope. It is generally believed that when $^3He/^4He(R)$ in a gas sample from a hot spring exceeds $^3He/^4He(R)$ in the atmosphere, it can be concluded that mantle-source. And temperatures of hot springs are rising steadily to $83^{\circ}C$. It is unrest signals at the Baegdusan, which is potentially active. The Baegdusan volcano is now in unrest status, there is eruption threat in the near future. Intensified monitoring and emergency response plan for volcanic risk mitigation are urgent for the volcano.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.5A
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• pp.565-575
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• 2009

In recent years, there have been numerous explosion-related accidents due to military and terrorist activities. Such incidents caused not only damages to structures but also human casualties, especially in urban areas. To protect structures and save human lives against explosion accidents, better understanding of the explosion effect on structures is needed. In an explosion, the blast load is applied to concrete structures as an impulsive load of extremely short duration with very high pressure and heat. Generally, concrete is known to have a relatively high blast resistance compared to other construction materials. However, normal strength concrete structures require higher strength to improve their resistance against impact and blast loads. Therefore, a new material with high-energy absorption capacity and high resistance to damage is needed for blast resistance design. Recently, Ultra High Strength Concrete(UHSC) and Reactive Powder Concrete(RPC) have been actively developed to significantly improve concrete strength. UHSC and RPC, can improve concrete strength, reduce member size and weight, and improve workability. High strength concrete are used to improve earthquake resistance and increase height and bridge span. Also, UHSC and RPC, can be implemented for blast resistance design of infrastructure susceptible to terror or impact such as 9.11 terror attack. Therefore, in this study, the blast tests are performed to investigate the behavior of UHSC and RPC slabs under blast loading. Blast wave characteristics including incident and reflected pressures as well as maximum and residual displacements and strains in steel and concrete surface are measured. Also, blast damages and failure modes were recorded for each specimen. From these tests, UHSC and RPC have shown to better blast explosions resistance compare to normal strength concrete.