• Proceedings of the Korea Water Resources Association Conference
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• 2023.05a
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• pp.166-166
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• 2023

Compound hazards (CHs) are two or more extreme climate events combined which occur simultaneously in the same region at the same time. Compared to individual hazards, the combination of hazards that cause CHs can result in greater economic losses and deaths. While several extreme climate events have been recorded across Asia for the past decades, many studies have only focused on a single hazard. In this study, we assess the spatiotemporal pattern of dry compound hazards which includes drought, heatwave, fire and wind across Asia for the last 42 years (1980-2021) using the historical data from ERA5 Reanalysis dataset. We utilize a daily spatial data of each climate event to assess the occurrence of such compound hazards on a daily basis. Heatwave, fire and wind hazard occurrences are analyzed using daily percentile-based thresholds while a pre-defined threshold for SPI is applied for drought occurrence. Then, the occurrence of each type of compound hazard is taken from overlapping the map of daily occurrences of a single hazard. Lastly, a multivariate assessment are conducted to quantify the occurrence frequency, hotspots and trends of each type of compound hazard across Asia. By conducting a multivariate analysis of the occurrence of these compound hazards, we identify the relationships and interactions in dry compound hazards including droughts, heatwaves, fires, and winds, ultimately leading to better-informed decisions and strategies in the natural risk management.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.22 no.1
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• pp.33-45
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• 2019

Compound disaster is the type that increases the impact affected by two or more hazard events, and attention to compound disaster and multi-hazards risk is growing due to potential damages which are difficult to predict. The objective of this study is to analyze the possible impacts of post-fire landslide scenario quantitatively by using TRIGRS (Transient Rainfall Infiltration and Grid-Based Regional Slope-Stability Analysis), a physics-based landslide model. In the case of wildfire, soil organic material and density are altered, and saturated hydraulic conductivity decrease because of soil exposed to high temperature. We have included the change of soil saturated hydraulic conductivity into the TRIGRS model through literature review. For a case study, we selected the area of $8km^2$ in Pyeongchang County. The landslide modeling process was calibrated before simulate the post-wildfire impact based on landslide inventory data to reduce uncertainty. As a result, the mean of the total factor of safety values in the case of landslide was 2.641 when rainfall duration is 1 hour with rainfall intensity of 100mm per day, while the mean value for the case of post-wildfire landslide was lower to 2.579, showing potential landslide occurrence areas appear more quickly in the compound disaster scenario. This study can be used to prevent potential losses caused by the compound disaster such as post-wildfire debris flow or landslides.

• Journal of the Korean Society of Safety
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• v.18 no.3
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• pp.94-100
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• 2003

Gel-like compounds containing flammable solvents were prepared to use fur cleaning agents in field of innovative industries and general purposes. And experiments were conducted to improve the defects of liquified flammable solvents from the view point of safety and health hazards. Flammable solvents used in this study were several single component flammable solvents(turpentine oil, N-methyl-2-pyrrolidone(NMP), d-limonene) and multi component flammable solvent(gasoline and ethanol). For gelation of flammable solvents, commercially Known as Aerosil(equation omitted) 200 fumed silica and triethanolamine(TEA) were used as gelation agent dispersant. The analyses on properties of gel-like compounds was studied by gelation and viscosity test pH test, volatility test and differential scanning calorimetry(DSC) measurement. The experimental results indicate that gel-like compounds containing flammable solvents have pH stability, high viscosity, volatile organic compounds(VOC) control by the decrease of volatility and odor component generation, fluidity control etc. From the experimental values, it can be predicted that the safety in the working place is improved by manufacturing flammable solvents into gel-like compounds.

• Fire Science and Engineering
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• v.33 no.4
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• pp.16-27
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• 2019

A burning test was conducted on the smoke and combustion gases generated from cypress wood treated with sodium silicate, 3-aminopropyltrimethoxysilane sol, 3-(2-aminoethylamino)propylmethyldimethoxysilane sol, and 3-(2-aminoethylamino) propyltrimethoxysilane sol. The silicone compound sol was applied to each of the cypress wood specimens three times with a brush. The smoke and combustion generation gas were analyzed using a cone calorimeter (ISO 5660-1) and the smoke was also evaluated by applying new smoke risk assessment method. The smoke performance index (SPI) of the cypress treated with silicone compound increased 1.66 to 8.42 times and the smoke growth index (SGI) was 11.8 to 88.2%, respectively. The smoke intensity (SI) is expected to be 1.0~50.5% lower than that of the base specimens, resulting in lower smoke and fire hazards. The third maximum carbon monoxide (CO_peak) concentration of the specimens treated with silicone compounds was 22.5~33.3% lower than that of the base specimens. On the other hand, it produced potentially fatal toxicity that was 1.48~1.72 times higher than the US Occupational Safety and Health Administration (OSHA) acceptance standard (PEL). Cypress wood itself produced a high carbon monoxide concentration, but the silicon compound played a role in reducing this level.

• Fire Science and Engineering
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• v.32 no.3
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• pp.19-26
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• 2018

Experiments on the combustion characteristics of untreated wood specimens and also treated ones with boric acid and ammonium pentaborate were carried out using a cone calorimeter according to ISO 5660-1 standard. As a result, comparing to untreated specimen, the fire performance index (FPI) of the specimens treated with boron compounds increased by 1.2 to 2.1 times and the fire growth index (FGI) increased by 1.6 to 8.4%. Also, total smoke release rate (TSR) was 9.0 to 28.3% lower than that of the untreated specimen. It is understood that the test specimens treated with the boron compound produces a carbonized layer with a flame retarding effect. The highest CO concentration, 0.01112%, for the untreated specimen was observed at 418 s, but the specimens treated with boron compound decreased 13.2 to 37.5% compared to untreated specimen. Therefore, wood treated with boron compounds is expected to have lower fire hazards and risks.

• Journal of Food Hygiene and Safety
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• v.22 no.2
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• pp.82-87
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• 2007

This research was performed to investigate chemical and microbiological hazards of Ready-to-eat(RTE) compound foods which uses the by-product of meat. For this experiment, 51 samples of RTE compound foods in by-product of meat distributed in Incheon from January to December 2006 were tested. The contents of heavy metals in the main ingredient of RTE compound foods were in the range of $0.073{\sim}0.112ppm$ for lead (Pb), $0.006{\sim}0.013ppm$ for cadmium (Cd) and $0.746{\sim}0.978ppb$ for mercury (Hg). The concentrations of residual ABS(alkyl benzene sulfate) in the small intestine which is a main ingredient of Gopchang-casserole were $$0.8ppm{\sim}57.6ppm$ (Ave. 10.3ppm). Staphylococcus aureus was isolated from 11 samples (21.6%) among 51 main ingredients of RTE compound foods. The isolation rates of Salmonella spp. and Clostridium perfringens were 2.0% (1/51) and 5.9% (2/51), respectively. By types of main ingredient, the small intestine was showed the highest isolation rate as 35.3% (12/34), ham and the sausage which are main ingredients of the Budae-pot stew were 25% (2/8) and other meat products were 20% (1/5). Food poisoning bacteria was not found in the blood of pig which is a main ingredient of the Sunji-pot stew. 28.4% (27/95) of sauce included in each RTE compound foods were coliform bacteria positive. Pesticide residues were found in four of 45 vegetables which are the additional ingredient of RTE compound foods. The concentrations of pesticide were chlorothalonil 2.8 ppm, EPN 10.3 ppm, chlorpyrifos 0.4ppm and indoxacarb 0.7ppm. In 33 bean sprout samples, captan and carbendazim were not detected.

• Journal of the Society of Disaster Information
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• v.19 no.3
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• pp.532-544
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• 2023

Purpose: To identify and evaluate the risk of chemical fire causative substances by using thermal analysis methods (DSC, TGA) for the hazards and physical property changes that occur when newly used biofuels are mixed with existing fuels It is to use it for identification and evaluation of the cause of fire by securing data related to the method and the hazards of the material according to it. Method: The research method used in this experiment is the differential scanning calorimeter (DSC: Difference in heat flux) through quantitative information on the caloric change from the location, shape, number, and area of peaks. flux) was measured, and the weight change caused by decomposition heat at a specific temperature was continuously measured by performing thermogravimetric analyzer (TGA: Thermo- gravimetric Analyzer). Result: First, in the heat flux graph, the boiling point of the material and the intrinsic characteristic value of the material or the energy required for decomposition can be checked. Second, as the content of biodiesel increased, many peaks were identified. Third, it was confirmed through analysis that substances with low expected boiling points were contained. Conclusion: It was shown that the physical risk of the material can be evaluated by using the risk of biodiesel, which is currently used as a new energy source, through various physical and chemical analysis techniques (DSC + TGA).In addition, it is expected that the comparison of differences between test methods and the accumulation and utilization of know-how on experiments in this study will be helpful in future studies on physical properties of hazardous materials and risk assessment of materials.

• Applied Chemistry for Engineering
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• v.29 no.6
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• pp.670-676
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• 2018

Experiments on combustion gases generation of untreated cypress specimens or treated with boric acid, ammonium pentaborate, and boric acid/ammonium pentaborate additive were carried out. Test specimens were painted three times with 15 wt% boron compound aqueous solutions. After drying, the generation of combustion gas was analyzed using a cone calorimeter (ISO 5660-1). As a result, comparing to untreated specimen, the smoke performance index (SPI) of the specimens treated with the boron compound increased by 1.37 to 2.68 times and the smoke growth index (SGI) decreased by 29.4 to 52.9%. The smoke intensity (SI) of the specimens treated with boron compounds is expected to be 1.16 to 3.92 times lower than that of untreated specimens, resulting in lower smoke and fire hazards. Also, the maximum carbon monoxide ($CO_{peak}$) concentration of specimens treated with boron compounds was 12.7 to 30.9% lower than that of untreated specimens. However, it was measured to produce fatal toxicities from 1.52 to 1.92 times higher than that of permissible exposure limits (PEL) by Occupational Safety and Health Administration (OSHA). The boron compounds played a role in reducing carbon monoxide, but it did not meet the expectation of reduction effect because of the high concentration of carbon monoxide in cypress itself.

• Molecular & Cellular Toxicology
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• v.4 no.1
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• pp.45-51
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• 2008

Volatile Organic Compounds (VOCs) have been shown to cause nervous system disorders through skin contact or respiration, and also cause foul odors even at low densities in most cases. Also, as a compound itself, VOCs are directly harmful to the environment and to the human body, and may participate in photochemical reactions in air to create secondary pollutants. In this study, HL-60 cells were treated with volatile organic compounds, including ethylbenzene and trichloroethylene, at a value of $IC_50$. Then, the in house-prepared Human HazChem arrayer was utilized in order to compare the gene expression between the two VOCs. After hybridization, 8 upregulated genes and 8 downregulated genes were discovered in the HazChem array. The upregulated genes were identified as SG15, TNFSF10, PRNP, ME1, NCOA4, SRXN1, TXNRD1, and XBP1. The downregulated genes were identified as MME, NRF1, PRARBP, CALCA, CRP, BAX, C7 or f40, and FGFR1. Such results were highly correlated with the quantitative RT-PCR results. The majority of the 16 genes were related with the characteristics of VOCs, including respiratory mechanism, apoptosis, and carcinogenesis-associated genes. Our data showed that our human HazChem array can be used to monitor hazardous materials via gene expression profiling.

• Proceedings of the Korea Water Resources Association Conference
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• 2023.05a
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• pp.348-348
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• 2023

최근 전세계 곳곳에서는 다양한 유형의 물 관련 복합재해가 발생하고 있다. 일례로 미국 캘리포니아 지역은 2014년부터 2017년까지 극심한 가뭄에 시달리다가 대기강(atmospheric river)의 영향으로 인하여 대규모의 홍수가 잇달아 발생하였다. 유럽에서는 2021년 전례 없는 홍수 직후 500년 빈도의 가뭄이 발생하면서 심각한 인명 및 재산피해가 발생하였다. 짧은 시간 동안 양극단의수재해가 연속적으로 발생하거나, 가뭄과 폭염, 홍수와 산사태의 결합, 또는 동시에 여러 지역에서 홍수나 가뭄이 발생하는 현상 등도 복합재해에 해당한다. 즉, 복합재해는 서로 다른 특성의 독립적인 수재해가 결합되어 나타나는 재해의 한 형태로써, 발생 빈도는 적으나 유발되는 피해는 매우 크다. 더욱이 복합재해는 미래에 더욱 빈번하게, 극심하게 발생할 것으로 예상되고 있다. Single Model Initial-condition Large Ensemble (SMILE)은 복합재해의 분석에 적합한 자료로 최근 활용사례가 증가하고 있다. 기존의 기후변화 관련 연구는 여러 기후모델에서 생산한 단일 모의자료를 앙상블의 형태로 이용하여 기후요소 및 기후재해의 미래 전망이나 거동을 분석하는 과정에 기반해왔다. 이 기후모델 앙상블은 모델 간 불확실성은 고려할 수 있으나 기온 상승 시나리오의 불확실성 및 기후 시스템 내부의 변동성은 고려하지 못하는 한계가 있다. 이에 미국의 National Center for Atmospheric Research에서는 자연 자체의 변동에 의한 불확실성을 모의할 수 있는 SMILE을 개발하였다. SMILE은 단일 기후모델에서 N개의 다중 모의자료 앙상블을 출력한다. 기존의 기후모델과 유사한 과정으로 모의를 수행하되, 미세한 섭동을 부여함으로써 자연적으로 발생하는 기후시스템 내부의 변동성을 고려한다. 이러한 실험 설정은 카오스 이론에 근거한다. 여러 기후모델에 대해 SMILE 기반 모의를 수행하면 앙상블의 앙상블 개념(large ensemble)이므로 방대한 양의 기후모의 자료가 확보되어 다양한 목적의 연구에 활용할 수 있다. SMILE은 기존의 다중 기후모델 앙상블이 고려할 수 없었던 종류의 불확실성을 추가적으로 고려함으로써 인간의 활동과 자연적 변동성이 복합재해에 미치는 상대적 영향을 정량적으로 평가할 수 있게 한다. 복합재해 연구에 필수적인 표본 수 부족의 한계를 극복할 수 있기 때문에 최근 기후변화 및 수자원 관련 연구에서 적극적으로 활용되고 있다. 또한, 미래 기후를 모의하기 때문에 복합재해 발생의 특성 및 거동을 전망할 수 있고, 충분한 수의 표본은 통계분석 결과에 신뢰성을 부여할 수 있다. 이러한 SMILE의 장점은 향후 더욱 다양한 연구의 기회를 제공할 것이다.