• The Journal of the Convergence on Culture Technology
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• v.9 no.3
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• pp.607-617
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• 2023

This study aims to analyze whether the performance of the fire extinguisher meets the criteria for the apparent specific gravity property test by calculating the change in internal pressure and the use period of the fire extinguisher as a new one with 5 years, recycled one with 5 years, a new one with 10 years, and a new one with 13 years, respectively. As a result of the experiment, when the internal pressure of the fire extinguisher was 0%, the first, second, and third arithmetic mean analysis of the dry chemical extinguisher according to the use period was found to be condemned. When the internal pressure of the fire extinguisher was 50%, it was measured as 130 ml in sample 12-08-new and analyzed as unsuitable. Also, sample 09-09-new of a new dry chemical extinguisher with 13 elapsed years measured 145ml, which was found inappropriate. All other dry chemical extinguishers were analyzed to be suitable. All were noted suitable when having normal internal pressure of the fire extinguisher, except for sample 09-06 of a new dry chemical extinguisher with 13 elapsed years, which was determined to be unsuitable caused by measuring as 131 ml for experimental value. As a result of experiments, some of the apparent specific gravity tests of dry chemical extinguishers from 10 years to 13 years have found that they are unsuitable for the performance of the fire extinguishers due to the massive phenomenon. Accordingly, it is necessary to reduce the endurance period of dry chemical extinguishers from 10 years to 7 years.

• The Journal of the Convergence on Culture Technology
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• v.9 no.2
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• pp.171-179
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• 2023

Due to man-made climate change, global abnormal weather phenomena have occurred, increasing disasters. Major developed countries(military) are preparing for disasters caused by extreme weather appearances. However, currently, disaster prevention plans and facilities have been implemented based on the frequency and intensity method based on statistical data, it is not enough to prepare for disasters caused by frequent extreme weather based on probability basis. The U.S. and British forces have been the fastest to take research and policy approaches related to climate change and the threat of disaster change, and are considering both climate change mitigation and adaptation. The South Korean military regards the perception of disasters to be storm and flood damage, and there is a lack of discussion on extreme weather and disasters due to climate change. In this study, the process of establishing disaster management systems in developed countries(the United States and the United Kingdom) was examined, and the response policies of each country(military) were analyzed using literature analysis techniques. In order to maintain tight security, our military should establish a response policy focusing on sustainability and resilience, and the following three policy approaches are needed. First, it is necessary to analyze the future operational environment of the Korean Peninsula in preparation for the environment that will change due to climate change. Second, it is necessary to discuss climate change 'adaptation policy' for sustainability. Third, it is necessary to prepare for future disasters that may occur due to climate change.

• Journal of the Korea institute for structural maintenance and inspection
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• v.27 no.2
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• pp.8-16
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• 2023

This study evaluated a shear capacity of confined socket-bolt (CSB) shear connector developed for utilizing cast in placed pile (CIP) as a permanent underground wall. The push-out tests were performed in the specimens with different CIP types, CSB shear connector types, L/d, and concrete compressive strengths of concrete pile, and with or without waterproofing at interfaces between CIP and underground wall. Test results showed that the specimens with a H-shaped pile were fractured in the CSB shear connector, while the fracture concentrated in the concrete part of the specimens with a reinforced concrete pile was alleviated as the compressive strength of the concrete pile increased, resulting in the severe fracture of CSB shear connector. The maximum shear capacities of the specimens with high strength bolts and reinforcing bars used as CSB shear connector were approximately 1.22 and 1.20 times higher than those of the specimens with a H-shaped pile, respectively, and 1.10 and 1.16 times higher than those of the specimens with a reinforced concrete pile, respectively. Meanwhile, the maximum shear capacity was not significantly affected by the embedding length of the CSB shear connector and overlapping length of reinforcing bar. The predicted shear capacities calculated from the KDS standards were lower than the measured values of all specimens tested in this study.

• Journal of Korean Tunnelling and Underground Space Association
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• v.12 no.1
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• pp.43-49
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• 2010

The escape connecting gallery in a tunnel on a road is one of emergency equipment to ensure safety for passer in the tunnel against the tunnel fire. Government stipulate over 500m tunnel has the cross passage at intervals of less then 250 m. However, this lump estimated interval is generated the concerns of exaggeration and under construction because peculiarity of the tunnel ex. The velocity of the tunnel airflow, an incline, degree of a fire, and innering area are not considered. The study indicate the way to estimate of the cross passage considered an incline and the velocity of the tunnel airflow for efficient application of cross passage on the tunnel design. As a result, in 0.0 m/s and 1.0 m/s of the velocity of the tunnel airflow case, the movement of smoke is influenced by the incline however, in 20 m/s case, it isn't influenced by incline much. According to the velocity of tunnel airflow and the incline, optimum interval of cross passage is not corresponded. Therefore established lump estimate that has 250 m intervals would be changed to estimate of optimum interval of cross passage that considered about the properties of tunnel, the velocity of the tunnel airflow, incline, degree of a fire and innering area of the tunnel.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.30 no.3B
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• pp.269-276
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• 2010

Climatic disasters are globally soaring due to recent acceleration of global warming. Especially the occurrence frequency of heavy rainfalls is increasing since the rainfall intensity is increasing due to the change of rainfall pattern, This study proposed the non-stationary frequency analysis for estimating design rainfalls in a design target year, considering the change of rainfall pattern through the climatic change scenario. The annual rainfalls, which are regionally downscaled from the BCM2 (A2 scenario) and NCEP data using a K-NN method, were used to estimate the parameters of a probability distribution in a design target year, based on the relationship between annual mean rainfalls and distribution parameters. A Gumbel distribution with a probability weighted method was used in this study. Seoul rainfall data, which are the longest observations in Korea, were used to verified the proposed method. Then, rainfall data at 7 stations, which have statistical trends in observations in 2006, were used to estimate the design rainfalls in 2020. The results indicated that the regional annual rainfalls, which were estimated through the climate change scenario, significantly affect on the design rainfalls in future.

• Proceedings of the Korea Water Resources Association Conference
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• 2022.05a
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• pp.234-234
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• 2022

도로에서의 우수를 원활하게 처리하기 위해서 빗물받이 및 연결관 등의 노면 배수시설이 설치되고 있으며, 노면 배수는 측구부를 통해 흘러 빗물받이 유입부로 차집되고 연결관을 통해 하수관거로 배수된다. 그러나 최근 국내 기상패턴의 변화로 국지성 집중호우와 같이 시간당 강우량 증가로 도로부와 저지대에서 배수시설의 배수불량에 따른 도심지 내수침수 피해가 발생하고 있다. 이에 정부에서는 다양한 우수관거 개선사업, 빗물펌프장, 지하저류조와 같은 방재시설을 설치하고 있으나 우수유출저감시설은 대규모 예산이 소요되고 실제 침수지역에 피해 저감효과에 대한 효용성 문제에 대한 제기뿐만 아니라 과밀화된 도심지에서는 지하공간 활용에 한계가 있는 실정이므로 도심지의 다양한 공간을 활용한 도시 배수 및 저류시설에 대한 연구가 필요하다. 따라서 본 연구에서는 유휴 공간인 도로 측구부 공간을 활용하여 도로 노면수를 저류 및 지체할 수 있는 노면수 측구 저류시설의 개념을 제시하고 측구저류조의 활용성을 판단하기 위하여 빗물받이 유입구, 빗물받이, 측구 저류조 및 빗물받이와 측구저류조 연결부에서의 노면수 유입, 유출 및 저류 등의 다양한 흐름 변화를 확인하기 위하여 Fluent 모형의 적용성을 분석하였다. 수치모의 전체 형상은 50x50cm 크기의 빗물받이를 기준으로 양쪽에 2m 길이의 측구 저류조를 원형관으로 연결하여 1/5 축소모형으로 구성하고 격자는 빗물받이 유입부, 빗물받이 및 측구 저류조 내부의 복잡한 3차원 흐름을 모의하기 위해 사면체와 육면체로 조밀하게 생성하였다. 다상유동해석을 위해 VOF(Volume of Fluid)방법을 적용하였고, 수치해석 방법으로는 비정상류, 난류 모형으로는 SST k-ω모형을 적용하였다. 수치모의 조건으로는 설계빈도별(5~30년) 우수유출량을 산정하여 유입 유량별 기존 빗물받이 유입부에서의 유입흐름, 빗물받이 내부에서의 와 발생흐름, 측구 저류조 및 연결관에서의 흐름을 구현하여 분석하였다. 수치모의 결과 빗물받이 유입부에서 연결관을 통한 측구 저류조로 유입되는 유입흐름과 빗물받이 하단부의 배수관을 통해 유출되는 흐름을 정상적으로 구현하였으며, 빗물받이 유입부 및 측구 저류조 연결관에서의 유속변화도 확인할 수 있었다. 또한 빗물받이와 측구 저류조에서 다양한 흐름을 구현하기 위한 Flunet 모형의 적용성을 검토하였으며, 향후 수리실험을 통하여 실제 흐름과의 매개변수 최적화 및 다양한 도로 조건의 변화를 고려한 수치모의 분석을 통하여 지속적인 모형의 검증이 가능할 것으로 판단된다.

• Korean Journal of Agricultural and Forest Meteorology
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• v.25 no.4
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• pp.404-414
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• 2023

In this study, digital climate maps with high-resolution (1km, daily) for the period of 1981 to 2020 were produced for the use as reference data within the procedures for statistical downscaling of climate change scenarios. Grid data for the six climate variables including maximum temperature, minimum temperature, precipitation, wind speed, relative humidity, solar radiation was created over Korean Peninsula using statistical downscaling model, so-called IGISRM (Improved GIS-based Regression Model), using global reanalysis data and in-situ observation. The digital climate data reflects topographical effects well in terms of representing general behaviors of observation. In terms of Correlation Coefficient, Slope of scatter plot, and Normalized Root Mean Square Error, temperature-related variables showed satisfactory performance while the other variables showed relatively lower reproducibility performance. These digital climate maps based on observation will be used to downscale future climate change scenario data as well as to get the information of gridded agricultural weather data over the whole Korean Peninsula including North Korea.

• Explosives and Blasting
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• v.41 no.4
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• pp.1-8
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• 2023

On August 4, 2020, 2750 tons of ammonium nitrate stored in a storage warehouse at the Port of Beirut exploded. This explosion is said to be the largest ammonium nitrate explosion ever. By applying the TNT equivalency method, TNT equivalent amount corresponding to the explosion energy of 2750 tons of ammonium nitrate was calculated, and it is found to be 856 tons. Overpressure and impulse were calculated in a range up to 3600 m from the blast using the Kingery-Bulmash explosion parameter calculator tool. As the distance from the explosion center increases, the overpressure and impulse decrease exponentially, but the overpressure decreases more significantly, showing that overpressure is more affected by distance than the impact. As a result of applying the damage criteria to evaluate the effects of overpressure and impulse on the structure, the critical distances at which partial collapse, major damage, and minor damage to the structure occur are found to be approximately 500, 800, and 2200 m from the center of the explosion, respectively. The probit function was applied to evaluate the probability of damage to structures and human body. The points where the probability of collapse, major damage, minor damage, and breakage of window-panes to structures are greater than 50% are found to be approximately 500, 810, 2200, and 3200 m, respectively. For people within 200 m from the center of the explosion, the probability of death due to lung damage is more than 99%, and the 50% probability of eardrum rupture is approximately 300 m. The points with a 100% probability of death due to skull rupture and whole body impact due to whole body displacement are evaluated to be 300 and 100 m, respectively.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.43 no.6
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• pp.883-896
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• 2023

As human activities in Korea are spread throughout the mountains, forest fires often affect residential areas, infrastructure, and other facilities. Hence, it is necessary to detect fire-damaged areas quickly to enable support and recovery. Remote sensing is the most efficient tool for this purpose. Fire damage detection experiments were conducted on the east coast of Korea. Because this area comprises a mixture of forest and artificial land cover, data with low resolution are not suitable. We used Sentinel-2 multispectral instrument (MSI) data, which provide adequate temporal and spatial resolution, and the k-nearest neighbor (kNN) algorithm in this study. Six bands of Sentinel-2 MSI and two indices of normalized difference vegetation index (NDVI) and normalized burn ratio (NBR) were used as features for kNN classification. The kNN classifier was trained using 2,000 randomly selected samples in the fire-damaged and undamaged areas. Outliers were removed and a forest type map was used to improve classification performance. Numerous experiments for various neighbors for kNN and feature combinations have been conducted using bi-temporal and uni-temporal approaches. The bi-temporal classification performed better than the uni-temporal classification. However, the uni-temporal classification was able to detect severely damaged areas.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.43 no.6
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• pp.775-784
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• 2023

In terms of flood management, it is necessary to analyze quantitative rainfall and runoff from a spatial and temporal perspective and to analyze runoff for heavy rainfall events that are concentrated within a short period of time. The simulation and analysis results of rainfall-runoff models vary depending on the type and input data. In particular, rainfall data is an important factor, so calculating areal mean rainfall is very important. In this study, the areal mean rainfall of the Samcheok Osipcheon(Riv.) watersheds located in the mountainous terrain was calculated using the Arithmetic Mean Method, Thiessen's Weighting Method, and the Isohyetal Method, and the rainfall-runoff results were compared by applying the distributional model S-RAT and the lumped model HEC-HMS. The results of the temporal transferability study showed that the combination of the distributional model and the Isohyetal Method had the best statistical performance with MAE of 64.62 m³/s, RMSE of 82.47 m³/s, and R² and NSE of 0.9383 and 0.8547, respectively. It is considered that this study was properly analyzed because the peak flood volume occurrence time of the observed and simulated flows is within 1 hour. Therefore, the results of this study can be used for frequency analysis in the future, which can be used to improve the accuracy of simulating peak flood volume and peak flood occurrence time in mountainous watersheds with steep slopes.