• Journal of the Society of Disaster Information
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• v.14 no.4
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• pp.399-408
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• 2018

Purpose: Recently, the ground subsidence has caused social problem, because it occurred life and economic damage. Method: Ground subsidence is different from a sink hole. Ground subsidence occurred cavities from loss of by groundwater flow, surface layer is collapsed due to relaxation and expansion. Results: According to the survey, the caused of ground subsidence are classified as ground cavities, surrounding ground relaxation and pipe joint failure. Conclution: Cavities of ground is mainly caused by cavities formed by rainfall induced infiltration of the heavy rainfall, loss of soil due to rise and fall of ground water level and repeated sewage runoff.

• Journal of Coastal Disaster Prevention
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• v.4 no.1
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• pp.7-19
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• 2017

In this study, waves and currents observed by acoustic AWAC, VECTOR and Aquadopp Profiler in Anmok coastal waters were analysed to account for the variability of wave and current and to understand the mechanism of sediment transport generated by wave-induced current in the surf-zone. The monthly variation of wave and residual currents were analysed and processed with long-term observed AWAC data at station W1, located at the water depth of about 18m measured during from February 2015 to September 2016. Wave-induced currents were also analysed with intensive field measurements such as wave, current, suspended sediment, and bathymetry data observed at the surf-zone during in winter and summer. The statistical result of wave data shows that high waves coming from NNE and NE in winter (DEC-FEB) are dominant due to strong winds from NE. But in the other season waves coming from NE and ENE are prevalent due to the seasonal winds from E and SE. The residual currents with southeastern direction parallel to the shoreline are dominant throughout a year except in winter showing in opposite direction. The speed of ebb-dominant southeastern residual currents decreasing from surface to the bottom is strong in summer and fall but weak in winter and spring. By analysing wave-induced current, we found that cross-shore current were generated by swell waves mainly in winter with incoming wave direction about $45^{\circ}$ normal to the shoreline. Depending on the direction of incoming waves, longshore currents in the surf-zone were separated to southeastern and northwestern flows in winter and summer respectively. The variation of observed currents near crescentic bars in the surf-zone shows different direction of longshore and cross-shore currents depending on incoming waves implying to the reason of beach erosion generating the beach cusp and sandbar migration during high waves at Anmok.

• Journal of Korean Association for Spatial Structures
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• v.21 no.1
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• pp.95-104
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• 2021

As people's living standards and cultural standards have developed, interest in culture and art has increased, and the demand for large space structures where people can enjoy art, music, and sports has increased. As it accommodates a large number of personnel, it is most important to ensure safety of large spatial structures, and can be used as a space where people can evacuate in case of a disaster. Large spatial structures should be prepared for earthquake loads rather than wind loads. In addition to damage to the structure due to earthquakes, there are cases in which it was not utilized as a space for evacuation due to the fall of objects installed on top of the structure. Therefore, in this study, the dome-shaped large spatial structure is generalized and the displacement response according to the number of installations, position and mass is analyzed using a tuned mass damper(TMD) that is representative vibration control device.

• Korean Journal of Environment and Ecology
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• v.25 no.5
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• pp.717-724
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• 2011

The objectives of this study were to analyze environment in the forest and growth characteristics for investigating the characteristics of Robinia pseudoacacia distribution in a Pinus thunbergii forest at the coast. As a result of analyzing inhibitory factors of Robinia pseudoacacia distribution in a Pinus thunbergii forest at the coast, it is considered that the salt level included in a sea wind is supposed to be the primary factor of the slow growth for Robinia pseudoacacia since brown leaves, wilting and early leaf fall have appeared in the 0m spot from the artificial dune which has the high salt level. However, the soil properties and light environment hardly have a effect on the growth of Robinia pseudoacacia because there is no difference among planting places. Also, the growth ring of the horizontal root in 2year individuals 0.1~0.2m away from the dune have been formed for 1 year only as a consequence of analyzing growth rings of Robinia pseudoacacia growing on the coast. It can be infered that the nourishment of the horizontal root from individuals growing on the coast have been provided for the first 1 year only. It is estimated that, in case of the nearby areas on the coast, it is not enough to provided nourishment to the horizontal root due to obstructing the growth of new individuals by a sea wind, so the growth of the horizontal root would be hampered. Therefore, it is considered that impedient Robinia pseudoacacia distribution in a Pinus thunbergii forest at the coast is caused by making no growth of new horizontal roots and newborn individuals.

• Journal of Korea Multimedia Society
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• v.23 no.2
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• pp.282-292
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• 2020

In order to minimize casualties from marine vessel accidents that occur frequently at home and abroad, it is important to ensure the safety of the passengers aboard the vessel in the event of an accident. There is an EPIRB system as a system for disaster preparedness in the marine situation currently on the market, but there is a problem that the price is very expensive. In order to overcome the cost problem, which is a disadvantage of previous system, LoRaWAN-based communication is used. LoRaWAN communication-based vessel positioning and risk detection system based on LoRaWAN communication transmits measurement data of each module using two Beacon and GPS modules to stably perform position measurement for both indoor and outdoor situations. The rider danger situation detection system can detect the safety status of the rider using the 3-axis acceleration sensor, collect data from the rider positioning system and the rider safety status detection system, and send to server using LoRa communication. When conducting communication experiments in the long-distance maritime situation and actual communication experiments using the implemented system, it was found that the two experiments showed over 90% communication success rate on average.

• Proceedings of the KAIS Fall Conference
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• 2011.05a
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• pp.161-164
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• 2011

본 논문에서는 MBR 공정 유출수의 화학응집에 따른 특성을 알아보고자 A2O공정 하수처리수를 대상으로 막의 공극 크기와 약품 교반시간 및 응집 침전시간에 따른 인 제거 효율을 조사하였다. 막 여과 전후의 시료에 대한 응집실험결과 막 여과 전후의 응집제 투입에 따른 인 제거효율은 막 여과 전 90%와 비교했을 때 각각 74.5, 71.2, 62.6%로 최고 37.4%까지 큰 차이를 보였으며 이것은 막 여과로 인하여 시료 내 존재하는 콜로이드성 물질들의 입자 크기가 작아져 응집반응을 위한 응집핵 형성에 영향을 주었기 때문이며 막의 공극 크기가 작을수록 인 제거 효율도 감소하는 것으로 나타났다. 완속교반과 침전시간을 길게 할수록 인 제거 효율이 증가하였다. 침전시간이 10분일 경우는 인 제거 효율이 막 여과 후의 시료에 대해서 각각 45.3, 35.1, 52.0%로 인 제거가 상당히 불안정하였고 60분일 경우에는 각각 83.4, 85.1, 80.7%로 탁월한 인 제거가 일어난 것을 알 수 있었다.

• Journal of the Korea Safety Management & Science
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• v.24 no.4
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• pp.125-134
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• 2022

Forest fires in Korea usually start in the fall and occur every year until spring. Most wildfires are human resources that combine topographical characteristics and carelessness, and failure to respond in the initial stage and lack of cleanup are spreading to large-scale wildfires. In order to prevent these wildfires, active cooperation from the public is essential. As can be seen from recent wildfires, the attention of the public is needed above all else because large-scale wildfires in Korea are occurring due to the people's negligence. If a wildfire spreads and becomes large, it causes damage to life and property, and the damage is irreversible. In this study, various methods were used to prevent forest fires and improve initial suppression ability. In order to minimize damage, the model analyzed by the 119 Special Rescue Team in Gangwon, Chungcheong and nearby forest fires was analyzed on the combustion progress and wind direction by time period. The propagation speed by the wind direction was simulated. Until now, most of the wildfires have been extinguished by firefighting, but I hope that the Forest Service will take the lead and maintain coordination with related organizations.

• Tunnel and Underground Space
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• v.22 no.6
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• pp.383-392
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• 2012

This study introduces $M_{(i,j,k)}BCP$ (Mining Business Continuity Planning) which is the smart management system of mine disasters to achieve the safe and eco-friendly mining. Where, 'i' is mine kinds, 'j' is mining processes, and 'k' is risks at process respectively. By specifically setting 'i=1=limestone mine', this study also suggests that $M_{(i,j,k)}BCP$ is the smart management system of limestone mine. Mining risks used in this study were obtained from professional survey and literature review. This study classified these risks by five different mining processes and reduced risk numbers approximately 60 to 26. And they were all allocated into $M_{(i,j,k)}BCP$ and assessed. To do assess risks, this study used four risk indexes which are probability, casualty, facility loss, and discontinuity respectively. By the results of the assessment of risks, results could be four specific groups based on their causes and impacts. In addition, one of the results showed that the most possible risks at limestone mine was the roof-fall and rock-fall in digging process. This result means that $M_{(1,2,1)}BCP$ should be established as a first priority at limestone mine.

• The Journal of Engineering Geology
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• v.33 no.3
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• pp.427-438
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• 2023

We carried out a geological survey to classify the types of mass movement in Danyang Geopark (where various rock types are distributed) and analyzed the mechanical and hydraulic characteristics of landslide materials using a series of laboratory tests. Debris flows occurred in areas of limestone/marble, shale, and porphyroblastic gneiss, and limestone/marble landslides were distinguished from the others through the presence of karren topography. Soil tests showed that soil derived from weathered gneiss, which has a higher proportion of coarse grains, has a higher friction angle, lower cohesion, and larger hydraulic conductivity than soils from areas of limestone/marble, and shale. Rock failure mass movements occurred in areas of phyllite, sandstone, and conglomerate and were subdivided into plane failure, block-fall, and boulder-fall types in areas of phyllite, sandstone, and conglomerate, respectively. The shear strength of phyllite is much lower than that of the other types of rock, which have similar rock quality. The slake durability index of the conglomerate is similar to that of the other rock types, which have similar degrees of weathering, but differential weathering of the matrix and clasts was clearly observed when comparing the samples before and after the test. This study can help establish appropriate reinforcement and disaster prevention measures, which depend on the type of mass movement expected given the geological characteristics of an area.

• Journal of Korea Multimedia Society
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• v.23 no.5
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• pp.710-720
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• 2020

Tsunami occurred by a rapid change in the ocean floor is a natural disaster that causes serious damage worldwide. South Korea seems to be out of the range of this damage, but it is quite possible that South Korea will fall within the range due to the long-distance propagation features of tsunami and many earthquakes occurred in Japan. However, the analysis and preparation for tsunami have been still insufficient. In this paper, we propose a tsunami simulation model based on cellular automata for analyzing coastal inundation. The proposed model calculates the range of inundation in coastal areas by propagating the energy of tsunami using the interaction between neighboring cells. We define interaction rules and algorithms for the energy transfer and propose a software tool to effectively utilize the model. In addition, to verify and tune the simulation model, we used the actual tsunami data in 2010 at Dichato, Chile. As a case study, the proposed model was applied to analyze the coastal inundation according to tsunami height in Gwangali Beach, a famous site in Busan. It is expected that the simulation model can be a help to prepare an effective countermeasure against tsunami and be used for a virtual evacuating training.