• 제목/요약/키워드: Deposition risk

검색결과 73건 처리시간 0.033초

산지재해 위험구간 예측을 위한 토석류 흐름 모의 (Movements Simulation of Debris Flow for Prediction of Mountain Disasters Risk Zone)

  • 오채연;전계원;강배동
    • 한국방재안전학회논문집
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    • 제15권4호
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    • pp.71-78
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    • 2022
  • 최근 산사태나 토석류와 같은 산지재해가 계류를 따라 흘러와 주거지 및 도로를 덮치는 피해가 증가하고 있으며 본 연구에서는 산지재해의 피해 저감 및 원인 분석을 위하여 토석류 발생지역을 대상으로 현장 조사 및 지상 LiDAR 지형 분석을 수행하고 토석류 수치 모형인 FLO-2D 와 RAMM 모형을 이용하여 토석류 유동 과정을 시뮬레이션하였다. 그리고 토석류 퇴적 면적을 산정하고 실제 발생 구간과 비교 분석하였다. 지상 LiDAR 스캔 자료의 토석류 발생 구간 퇴적 면적은 대략 21,336 m2로 산정되었으며 FLO-2D 모의 결과 20,425 m2, RAMMS 모형의 경우 19,275 m2로 분석되었다. 두 모형 모두 실제 발생 구간과 유사한 형태를 보였다. 구축된 지형자료는 재해 발생 위험지역의 안전성 확보를 위한 기초자료로 활용 가능할 것이다.

Internal Dosimetry: State of the Art and Research Needed

  • Francois Paquet
    • Journal of Radiation Protection and Research
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    • 제47권4호
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    • pp.181-194
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    • 2022
  • Internal dosimetry is a discipline which brings together a set of knowledge, tools and procedures for calculating the dose received after incorporation of radionuclides into the body. Several steps are necessary to calculate the committed effective dose (CED) for workers or members of the public. Each step uses the best available knowledge in the field of radionuclide biokinetics, energy deposition in organs and tissues, the efficiency of radiation to cause a stochastic effect, or in the contributions of individual organs and tissues to overall detriment from radiation. In all these fields, knowledge is abundant and supported by many works initiated several decades ago. That makes the CED a very robust quantity, representing exposure for reference persons in reference situation of exposure and to be used for optimization and assessment of compliance with dose limits. However, the CED suffers from certain limitations, accepted by the International Commission on Radiological Protection (ICRP) for reasons of simplification. Some of its limitations deserve to be overcome and the ICRP is continuously working on this. Beyond the efforts to make the CED an even more reliable and precise tool, there is an increasing demand for personalized dosimetry, particularly in the medical field. To respond to this demand, currently available tools in dosimetry can be adjusted. However, this would require coupling these efforts with a better assessment of the individual risk, which would then have to consider the physiology of the persons concerned but also their lifestyle and medical history. Dosimetry and risk assessment are closely linked and can only be developed in parallel. This paper presents the state of the art of internal dosimetry knowledge and the limitations to be overcome both to make the CED more precise and to develop other dosimetric quantities, which would make it possible to better approximate the individual dose.

과수원용 스프레이어의 농약 살포 및 비산 예측을 위한 전산유체해석 (CFD Modeling of Pesticide Flow and Drift from an Orchard Sprayer)

  • 홍세운;김락우
    • 한국농공학회논문집
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    • 제60권3호
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    • pp.27-36
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    • 2018
  • Effective pesticide applications are needed to assure the quality and economic competitiveness of fruit production and lower the risk of spray drift. Experimental studies have shown that better spray coverage and less driftability require an understanding of the transport of spray droplets within turbulent airflows in the orchard and the interaction between droplet dynamics and tree canopies. This study developed a computational fluid dynamics (CFD) model to predict pesticide flows in the orchard and spray drift discharged from an air-assisted orchard sprayer. The model represented the transport of spray droplets as well as droplets captured by tree canopies, which were modeled as a conical porous model and branched tree model. Validation of the CFD model was accomplished by comparing the CFD results with field measurements. Spray depositions inside tree canopies and at off-target locations were in good agreement with the measurements. The resulting data presented that 38.6%~42.3% of the sprayed droplets were delivered to the tree canopies while 13.6%~20.1% were drifted out of the orchard, part of them reached farther than 200 m from the orchard. The study demonstrates that CFD model can be used to evaluate spray application performance and spray drift potential.

동북 아시아 지역에서의 대기중 재료부식 시험에 관한 연구 (The Study on the Atmospheric Corrosion Tests of Materials in Northeast Asia)

  • 김선태;임봉빈
    • 한국환경과학회지
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    • 제7권3호
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    • pp.361-368
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    • 1998
  • The structure such as building and cultural properties was composed of various materials like wood, metal and stone that have been utilized and exposed to air, wind and rain far a long time. However, because of their special characteristics as structure, collecting of samples that may involve their destruction cannot be permitted, ever for material analysis. Therefore, h order to study the Influence of atmospheric pollution on structure, atmospheric corrosion tests were achieved by making use of materials(bronze. ancient copper, copper, steel and marble) in field exposure tests. Atmospheric exposure sites are selected from places which are characterized by urban, rural, Industrial and marine enoronments In Northeast Asia. According to the results of atmospheric corrosion tests: The corrosion rates of Industrial states In china were more serious than other sampling sites. In the correlation of meteorological factors. wet hours was defiled as Intogeacted hours under that atmospheric temperature is above $0^{\circ}C$ and relative humidity in above 80% that has a great influence on corrosion tests of materials in case of a short time. The relative humidity was above about 75% that resulted in great increase of corrosion rates. In the esimation of corrosion rates between materials, corrosion rates of steel was about thirty times and decuple larger than that of other materials excluding marble in unshelterd exposure and In sheltered exposure.

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Molecular and Cellular Basis of Neurodegeneration in Alzheimer's Disease

  • Jeong, Sangyun
    • Molecules and Cells
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    • 제40권9호
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    • pp.613-620
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    • 2017
  • The most common form of senile dementia is Alzheimer's disease (AD), which is characterized by the extracellular deposition of amyloid ${\beta}-peptide$ ($A{\beta}$) plaques and the intracellular formation of neurofibrillary tangles (NFTs) in the cerebral cortex. Tau abnormalities are commonly observed in many neurodegenerative diseases including AD, Parkinson's disease, and Pick's disease. Interestingly, tau-mediated formation of NFTs in AD brains shows better correlation with cognitive impairment than $A{\beta}$ plaque accumulation; pathological tau alone is sufficient to elicit frontotemporal dementia, but it does not cause AD. A growing amount of evidence suggests that soluble $A{\beta}$ oligomers in concert with hyperphosphorylated tau (pTau) serve as the major pathogenic drivers of neurodegeneration in AD. Increased $A{\beta}$ oligomers trigger neuronal dysfunction and network alternations in learning and memory circuitry prior to clinical onset of AD, leading to cognitive decline. Furthermore, accumulated damage to mitochondria in the course of aging, which is the best-known nongenetic risk factor for AD, may collaborate with soluble $A{\beta}$ and pTau to induce synapse loss and cognitive impairment in AD. In this review, I summarize and discuss the current knowledge of the molecular and cellular biology of AD and also the mechanisms that underlie $A{\beta}-mediated$ neurodegeneration.

포화 컬럼실험에서 이온강도 변화 및 유기물질 출현에 의한 PVP로 코팅된 은나노 입자의 거동 연구 (Transport behavior of PVP (polyvinylpyrrolidone) - AgNPs in saturated packed column: Effect of ionic strength and HA)

  • 허지용;한종훈;허남국
    • 상하수도학회지
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    • 제30권3호
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    • pp.263-270
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    • 2016
  • Recent Engineered nanoparticles were increasingly exposed to environmental system with the wide application and production of nanomaterials, concerns are increasing about their environmental risk to soil and groundwater system. In order to assess the transport behavior of silver nanoparticles (AgNPs), a saturated packed column experiments were examined. Inductively coupled plasma-mass spectrometry and a DLS detector was used for concentration and size measurement of AgNPs. The column experiment results showed that solution chemistry had a considerable temporal deposition of AgNPs on the porous media of solid glass beads. In column experiment, comparable mobility improvement of AgNPs were observed by changing solution chemistry conditions from salts (in both NaCl and $CaCl_2$ solutions) to DI conditions, but in much lower ionic strength (IS) with $CaCl_2$. Additionally, the fitted parameters with two-site kinetic attachment model form the experimental breakthrough curves (BTCs) were associated that the retention rates of the AgNPs aggregates were enhanced with increasing IS under both NaCl and $CaCl_2$ solutions.

Key Findings from the Artist Project on Aerosol Retention in a Dry Steam Generator

  • Dehbi, Abdelouahab;Suckow, Detlef;Lind, Terttaliisa;Guentay, Salih;Danner, Steffen;Mukin, Roman
    • Nuclear Engineering and Technology
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    • 제48권4호
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    • pp.870-880
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    • 2016
  • A steam generator tube rupture (SGTR) event with a stuck-open safety relief valve constitutes one of the most serious accident sequences in pressurized water reactors (PWRs) because it may create an open path for radioactive aerosol release into the environment. The release may be mitigated by the deposition of fission product particles on a steam generator's (SG's) dry tubes and structures or by scrubbing in the secondary coolant. However, the absence of empirical data, the complexity of the geometry, and the controlling processes have, until recently, made any quantification of retention difficult to justify. As a result, past risk assessment studies typically took little or no credit for aerosol retention in SGTR sequences. To provide these missing data, the Paul Scherrer Institute (PSI) initiated the Aerosol Trapping In Steam GeneraTor (ARTIST) Project, which aimed to thoroughly investigate various aspects of aerosol removal in the secondary side of a breached steam generator. Between 2003 and 2011, the PSI has led the ARTIST Project, which involved intense collaboration between nearly 20 international partners. This summary paper presents key findings of experimental and analytical work conducted at the PSI within the ARTIST program.

Direct Immunofluorescence in Clinically Diagnosed Oral Lichen Planus

  • Lee, Kyung-Eun;Suh, Bong-Jik
    • Journal of Oral Medicine and Pain
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    • 제41권1호
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    • pp.16-20
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    • 2016
  • Purpose: Oral lichen planus (OLP) is relatively common mucosal disease in clinical dentistry. OLP is intractable and regarded having malignant potential. Until now, there is some debate on how far OLP can be malignant, and which characteristics can be a risk factor for malignant transformation. Clinician need to know some differences between OLP and lesions similar to OLP to manage properly and suppose prognosis correctly. Therefore, the aim of this study was to divide clinical OLP into two groups and to compare the results of direct immunofluorescence (DIF) between two groups. Methods: This study was conducted on outpatients who visited at the department of Oral Medicine in Chonbuk National University Hospital from January 2007 to November 2015. Patients with DIF result were retrospectively reviewed. The selected patients were classified 'clinical typical of OLP' (CTO) or 'clinical compatible with OLP' (CCW) by modified World Health Organization diagnostic criteria of OLP and oral lichenoid lesion. Results: DIF were classified by deposition intensity or pattern of anti-human antibody and fibrinogen. The classification of fluorescence pattern in each specimen was graded as positive, possibly positive or negative. Conclusions: Both CTO and CCW had positive and possibly positive pattern. Prevalence of positive pattern was 68.8% in CTO and 52.6% in CCW and that of possibly positive pattern was 9.4% in CTO and 5.3% in CCW. Prevalence of negative was 21.8% in CTO and 42.1% in CCW.

발효 시금치 추출물의 무기인산염에 의해 유도된 혈관 석회화 저해 효과 (Inhibitory Effect of Fermented Spanish Extract on Inorganic phosphate-induced Vascular Calcification in ex vivo Aortic Rings)

  • 이상희;홍선미;성미정
    • 한국식생활문화학회지
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    • 제37권3호
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    • pp.248-255
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    • 2022
  • Spinach (Spinacia oleracea L.), a green leafy vegetable, is well known as a functional food due to its biological activities. Vascular calcification is associated with several disease conditions including atherosclerosis, diabetes, and chronic kidney disease (CKD), and is known to raise the risk of cardiovascular diseases related morbidity and mortality. However, there are no previous studies that have investigated the effects of fermented spinach exract (FSE) against aortic and its underlying mechanisms. Therefore, this study investigated the effects and action of possible mechanisms of FSE on inorganic phosphate (PI)-induced vascular calcification in ex vivo mouse aortic rings. PI increased vascular calcification through calcium deposition in ex vivo aortic rings. FSE inhibited calcium accumulation and osteogenic key marker, runt-related transcription factor 2 (Runx2), and bone Morphogenetic Protein 2 (BMP-2) protein expression in ex vivo aortic rings. And, FSE inhibited PI-induced extracellular signal-regulated kinase (ERK) and p38 phosphorylation in ex vivo aortic rings. These results show that FSE can prevent vascular calcification which may be a crucial way for the prevention and treatment of vascular disease association with vascular calcification.

SEMI S6를 적용한 CVD 설비의 폭발분위기 조성 가능성 분석 (Explosion Likelihood Investigation of Facility Using CVD Equipment Using SEMI S6)

  • 이미정;서대원;이성희;이동건;배세종;백종배
    • Korean Chemical Engineering Research
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    • 제61권1호
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    • pp.62-67
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    • 2023
  • 반도체, 디스플레이 등 IT(Information Technology) 제품 수요 증가로 관련 산업이 확대되고 있다. 이는 생산설비 증설과 화학물질 사용 증가로 이어지며 화재·폭발의 위험성에도 영향을 미치고 있다. 이러한 위험요인에 대해 정부는 오래전부터 인화성 물질을 제조·사용·취급하는 장소의 사고 예방을 위하여 산업안전보건법 및 KS 기준에 따라 폭발위험 장소로 설정하여 관리토록 하고 있다. 그러나, 폭발위험장소를 설정할 때, 중요한 요소인 환기량을 고려하지 않아 실질적인 폭발분위기 조성 가능성을 예측하기는 쉽지 않다. 이 연구에서는 디스플레이 산업에서 주요 공정인 CVD(Chemical Vapor Deposition) 설비에 SEMI S6 Exhaust Ventilation Test 방법을 적용하여 위험한 설비의 환기 성능을 평가하고, 폭발분위기 조성 가능성을 확인하였다. 그 결과, 가상의 시나리오 내에서 환기 성능이 SEMI S6에서 규정한 기준에 적합하였고, 폭발분위기가 조성될 가능성이 낮음을 확인하였다. 따라서, KS 규격뿐만 아니라 공학적 기법으로 폭발분위기의 형성 여부를 예측한 연구 결과를 통해 합리적이고 경제적인 사고 예방에 도움이 될 것으로 기대된다.