• 제목/요약/키워드: mines

검색결과 854건 처리시간 0.025초

Response of coal rock apparent resistivity to hydraulic fracturing process

  • Song, Dazhao;Wang, Enyuan;Qiu, Liming;Jia, Haishan;Chen, Peng;Wei, Menghan
    • Geomechanics and Engineering
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    • 제14권6호
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    • pp.581-588
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    • 2018
  • In order to explore the comprehensive evaluation means of the extent of hydraulic fracturing region in coal seams, we analyzed the feasibility of detecting the response of coal rock direct current (DC) apparent resistivity to hydraulic-fracturing using Archie's theory, and conducted experimental researches on the response of DC resistivity in the hydraulic fracturing process using small-scale coal rock samples. The results show that porosity and water saturation are the two factors affecting the apparent resistivity of coal rock while hydraulic fracturing. Water has a dominant effect on the apparent resistivity of coal rock samples. The apparent resistivity in the area where water flows through is reduced more than 50%, which can be considered as a core affect region of hydraulic fracturing. Stress indirectly impacts the apparent resistivity by changing porosity. Before hydraulic fracturing, the greater axial load applied, the more serious the rupture in the samples, resulting in the greater apparent resistivity. Apparent resistivity testing is a potential regional method to evaluate the influence range of hydraulic fracturing in coal seams.

Integration of Laser Scanning and Three-dimensional Models in the Legal Process Following an Industrial Accident

  • Eyre, Matthew;Foster, Patrick;Speake, Georgina;Coggan, John
    • Safety and Health at Work
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    • 제8권3호
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    • pp.306-314
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    • 2017
  • Background: In order to obtain a deeper understanding of an incident, it needs to be investigated to "peel back the layers" and examine both immediate and underlying failures that contributed to the event itself. One of the key elements of an effective accident investigation is recording the scene for future reference. In recent years, however, there have been major advances in survey technology, which have provided the ability to capture scenes in three dimension to an unprecedented level of detail, using laser scanners. Methods: A case study involving a fatal incident was surveyed using three-dimensional laser scanning, and subsequently recreated through virtual and physical models. The created models were then utilized in both accident investigation and legal process, to explore the technologies used in this setting. Results: Benefits include explanation of the event and environment, incident reconstruction, preservation of evidence, reducing the need for site visits, and testing of theories. Drawbacks include limited technology within courtrooms, confusion caused by models, cost, and personal interpretation and acceptance in the data. Conclusion: Laser scanning surveys can be of considerable use in jury trials, for example, in case the location supports the use of a high-definition survey, or an object has to be altered after the accident and it has a specific influence on the case and needs to be recorded. However, consideration has to be made in its application and to ensure a fair trial, with emphasis being placed on the facts of the case and personal interpretation controlled.

아메리카잎굴파리에 의한 거베라 피해잎의 조직학적 관찰 (Anatomical Observation of Leaf of Gerbera hybrida Hort. Injured by Liriomyza trifolii)

  • 정용모;김진기;안동춘;빈철구;이동우;손흥대;권오창
    • 원예과학기술지
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    • 제17권4호
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    • pp.485-488
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    • 1999
  • 아메리카잎굴파리에 의해 피해를 입은 거베라 잎의 피해부위인 흡즙 부위 및 식해흔의 내부조직 구조를 광학현미경(LM)과 주사전자현미경(SEM)을 이용하여 관찰하였다. 아메리카 잎굴파리에 의한 피해 잎의 내부조직 관찰 결과, 피해의 진행과정은 대개 3단계로 관찰할 수 있었다. 첫째, 초기 단계로 흡즙 후 산란하는 부위는 비교적 세포조직이 치밀한 책상조직이었으며, 둘째, 알에서 부화한 유충은 주위의 책상 조직만을 식해하면서 잎조직 속에서 굴을 만들기 시작하고, 세째, 성장한 유충은 점점 굴을 크게 하면서 성장하여 잎의 표피층을 뚫고 나오기 직전에는 1층의 책상조직과 책상조직에 연결된 2층의 해면조직까지 식해하면서 잎의 내부에 피해를 가하는 것을 관찰하였다.

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강릉·태백지역 석탄광산의 탄 및 호흡성 탄분진중 금속 농도 비교에 관한 연구 (Determination of Metals of Coal and Respirable Coal Dust in Gangneung and Taebaek Coal Mines)

  • 김해정;최호춘;정호근
    • 한국산업보건학회지
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    • 제1권1호
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    • pp.82-88
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    • 1991
  • Determination of Cu, Fe, Ni, Pb, and Zn concentrations in coal and respirable coal dust were performed by atomic absorption spectrophotometry. The coal samples of 18 coal mines in Gangneung area were collected and 25 coal mines in Taebaek area. Crushed coal samples were divided into three mesh sizes. The results were as follows : 1. Metal concentrations of coals in Gangneung area by sieve sizes( -100/+200 mesh, -200/+325 mesh, -325 mesh) were as follows: Cu ; 20, 18, 19, Fe ; 1,830, 1,765, 1,107, Pb ; 6, 8, 14, Ni ; 17, 17, 14, Zn ; 4, 2, $4{\mu}g/g$, respectively. Metal concentrations in coals in Taebaek area by sieve sizes(-100/+200 mesh, -200/+325 mesh, -325 mesh) were as follows: Cu ; 30, 32, 26, Fe ; 1,741, 1,822, 1,773, Pb ; 8, 9, 7, Ni ; 13, 13, 13, Zn ; 8, 5, $4{\mu}g/g$, respectively. There were not significant differences of Cu, Fe, Ni, Pb, and Zn concentrations of coals statistically in Gangneung and Taebaek area by sieve size. 2. Metal concentrations of coals in Gangneung and Taeback area were as follows : Cu ; 19, 30, Fe ; 1,514, 1,778, Pb ; 9, 8, Ni ; 16, 13, Zn ; 3, $6{\mu}g/g$, respectively. Differences of copper and zinc concentrations of coal samples were significant between Gangneung and Taebaek area, but those of iron, nickel and lead concentrations were not significant. 3. Copper, iron, lead, nickel and zinc concentrations of coals and respirable coal dust were as follows : Cu ; 30, 6, Fe ; 1,779, 5,075, Pb ; 8, 7,814, Ni ; 13, 5,681, Zn ; 5, $134{\mu}g/g$, respectively. Differences of nickel, lead and zinc concentrations were significant between coals and respirable coal dust but those of copper and iron concentrations were not significant.

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논토양의 이화학적 특성 및 침출성 중금속 함량을 이용한 비소의 전함량 예측 (Model Development for Estimating Total Arsenic Contents with Chemical Properties and Extractable Heavy Metal Contents in Paddy Soils)

  • 이정미;고우리;;류지혁;김지영;김두호;김원일
    • 한국토양비료학회지
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    • 제45권6호
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    • pp.920-924
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    • 2012
  • This study was performed to estimate total contents of arsenic (As) by stepwise multiple-regression analysis using chemical properties and extractable contents of metal in paddy soil adjacent to abandoned mines. The soil was collected from paddies near abandoned mines. Soil pH, electrical conductively (EC), organic mater (OM), available phosphorus ($P_2O_5$), and exchangeable cations (Ca, K, Mg, Na) were measured. Total contents of As and extractable contents of metals were analyzed by ICP-OES. From stepwise analysis, it was showed that the contents of extractable As, available phosphorus, extractable Cu, exchangeable K, exchangeable Na, and organic mater significantly influenced the total contents of As in soil (p<0.001). The multiple linear regression models have been established as Log (Total-As) = 0.741 + 0.716 Log (extractable-As) - 0.734 Log (avail-$P_2O_5$) + 0.334 Log (extractable-Cu) + 0.186 Log (exchangeable-K) - 0.593 Log (exchangeable-Na) + 0.558 Log (OM). The estimated value in total contents of As was significantly correlated with the measured value in soil ($R^2$=0.84196, p<0.0001). This predictive model for estimating total As contents in paddy soil will be properly applied to the numerous datasets which were surveyed with extractable heavy metal contents based on Soil Environmental Conservation Act before 2010.

국내 지하 석회석광산 갱도의 무지보 폭을 위한 제안 (Proposal of the Unsupported Span of Openings in the Domestic Underground Limestone Mines)

  • 선우춘
    • 터널과지하공간
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    • 제28권4호
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    • pp.358-371
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    • 2018
  • 지하광산에서 갱도나 공동의 안정성은 생산성과 안전을 확보해야 하는 광산운영에 있어서 가장 중요한 관심사이다. 공동의 안정성에 영향을 주는 많은 암반조건 중 공동의 폭과 높이는 중요한 설계요소가 된다. 이 논문의 주된 목적은 암반분류법 중에 Q시스템을 이용하여 무지보로 유지할 수 있는 최대 무지보갱도 폭을 국내 석회석 광산현장에서 용이하게 결정하기 위한 것이다. 국내 석회석 광산에서 무지보갱도 규격에 대한 고찰을 위해 여러 석회석 지하광산 200여개의 측점에서 암반분류 측정이 이루어졌다. Q 시스템을 이용한 무지보 갱도폭을 결정하는 관계식과 안정성 그래프법을 이용한 최대 무지보 갱도 폭을 결정하는 관계식을 유도하여 비교검토가 이루어졌다. 또한 현장에서 사용하기 쉽도록 GSI와 RMR을 결합한 새로운 방식의 분류법을 제안한다.