Environment, health and safety management in mining and other industries

Thesis (Ph.D.) University of Alaska Fairbanks, 2014While environment and health and safety may appear to be two different areas, they may be integrated into Environment, Health and Safety (EHS). This study is to investigate the impact of the environment and Occupational Health and Safety Management System (OHSMS) on health and safety. Three case studies were conducted. The first one is to study the impact of abandoned mines on soils, water and crops. The second one is to examine the effect of OHSMS implementation on reducing occupational safety risk. The third one examines the impact of environment on health. The abstracts of these three case studies are as follows: THE INVESTIGATION OF ARSENIC AND HEAVY METAL CONCENTRATIONS IN SOIL, WATER AND CROPS AROUND ABANDONED METAL MINES. Soils, water and crops around abandoned metal mines can be contaminated by heavy metals from adjacent tailings and waste rocks accumulated during mining operations. The results indicate that the As, Zn, Cd and Cr concentrations exceed the soil contamination standard in many soil samples of the nearby farmlands as well as the tailings sites. In the case of water quality, the As concentrations in the Okgae and Youngchen Mines show a decreasing trend with increasing distance from the mine, which is similar to that of the soil samples. The Cd and Pb concentrations in the crops near the Okgae Mine show a decreasing trend with increasing distance from the mine which is also similar to that of soil samples. In addition, the Cd and Pb concentrations in the rice samples and the Cd concentration in the corn samples increase with the Cd and/or Pb concentrations in the soil. EFFECT OF OHSMS ON WORK-RELATED ACCIDENT RATE AND DIFFERENCES OF OHSMS AWARENESS BETWEEN MANAGERS IN SOUTH KOREA's CONSTRUCTION INDUSTRY. The study was conducted to investigate the status of the occupational health and safety management system (OHSMS) in the construction industry and the effect of OHSMS on accident rates. Differences of awareness levels on safety issues among site general managers and occupational health and safety (OHS) managers are identified through surveys. The accident rates for the OHSMS-certified construction companies from 2006 to 2011, when the construction OHSMS became widely available, were analyzed to understand the effect of OHSMS on the work-related injury rates in the construction industry. The Korea Occupational Safety and Health Agency (KOSHA) 18001 is the certification to these companies performing OHSMS in South Korea. The questionnaire was created to analyze the differences of OHSMS awareness between site general managers and OHS managers of construction companies. The implementation of OHSMS among the top 100 construction companies in South Korea shows that the accident rate decreased by 67% and the fatal accident rate decreased by 10.3% during the period from 2006 to 2011. The survey in this study shows different OHSMS awareness levels between site general managers and OHS managers. The differences were motivation for developing OHSMS, external support needed for implementing OHSMS, problems and effectiveness of implementing OHSMS. Both work-related accident and fatal accident rates were found to be significantly reduced by implementing OHSMS in this study. The differences of OHSMS awareness between site general managers and OHS managers were identified through a survey. The effect of these differences on safety and other benefits warrants further research with proper data collection. THE ASSOCIATION BETWEEN CHILDHOOD ASTHMA AND RESIDENTIAL ENVIRONMENTAL RISK FACTORS THROUGH CASE-CONTROL STUDY IN ANDONG, KOREA. Using the International Society for Augmentative and Alternative Communication (ISAAC) questionnaire, we surveyed the childhood asthma prevalence and related socioeconomic and residential environment on 887 elementary schoolchildren in Andong, Korea. We selected asthma case group (29) and control group (26) and performed the exposure assessment for the personal exposure for Volatile Organic Compounds (VOCs) and formaldehyde level for 3 days. As a result, 814 schoolchildren completed the questionnaire. It was found that the asthma prevalence was 19.9% and gender (male, OR; Odds Ratio=1.55), age (younger, OR=1.60), family history of asthma (OR=3.70), passive smoking (OR=1.53), and odor from nearby house (OR=2.01) were affective factors. There was no significant difference between the case and control groups in VOCs and formaldehyde exposure level. In the logistic regression analysis, family income (aOR; adjusted OR =3.20, 95% CI=1.41-7.24) and amount of house sunlight (aOR=2.14, 95% CI; Confidence Interval =1.00-4.58) were significant after adjusting gender, age, and family history of asthma. In conclusion, socioeconomic factors including family income and residential environmental factors such as passive smoking, odor from nearby household, and amount of house sunlight are associated with the prevalence of childhood asthma

Vertex correction and Ward identity in the U(1) gauge theory with Fermi surface

We show that introduction of vertex corrections in the fully self-consistent ladder approximation does not modify dynamics of spinons and gauge fluctuations in the U(1) gauge theory with Fermi surface

Measurement of statistical evidence on an absolute scale following thermodynamic principles

Statistical analysis is used throughout biomedical research and elsewhere to assess strength of evidence. We have previously argued that typical outcome statistics (including p-values and maximum likelihood ratios) have poor measure-theoretic properties: they can erroneously indicate decreasing evidence as data supporting an hypothesis accumulate; and they are not amenable to calibration, necessary for meaningful comparison of evidence across different study designs, data types, and levels of analysis. We have also previously proposed that thermodynamic theory, which allowed for the first time derivation of an absolute measurement scale for temperature (T), could be used to derive an absolute scale for evidence (E). Here we present a novel thermodynamically-based framework in which measurement of E on an absolute scale, for which "one degree" always means the same thing, becomes possible for the first time. The new framework invites us to think about statistical analyses in terms of the flow of (evidential) information, placing this work in the context of a growing literature on connections among physics, information theory, and statistics.Comment: Final version of manuscript as published in Theory in Biosciences (2013

Evaluation of Die Trim Morphology Made by CAD-CAM Technology

Statement of problem The die contour can affect the emergence profile of prosthetic restorations. However, little information is available regarding the congruency between a stereolithographic (SLA) die and its corresponding natural tooth. Purpose The purpose of this vitro study was to evaluate the shapes of SLA die in comparison with the subgingival contour of a prepared tooth to be restored with a ceramic crown. Material and methods Twenty extracted human teeth, 10 incisors, and 10 molars, were disinfected and mounted in a typodont model. The teeth were prepared for a ceramic restoration. Definitive impressions were made using an intraoral scanner from which 20 SLA casts with removable dies were fabricated. The removable dies and corresponding human teeth were digitized using a 3-dimensional desktop scanner and evaluated with computer-aided design software. The subgingival morphology with regard to angle, length, and volume at the buccolingual and mesiodistal surfaces and at zones A, B, C, and D were compared. Data were first analyzed with repeated measures analysis of variance (ANOVA), using locations (buccolingual and mesiodistal), zones (A, B, C, and D), and model type (SLA and Natural) as within-subject factors and tooth type (molar and incisor) as the between-subject factor. Post hoc analyses were performed to investigate the difference between natural teeth and corresponding SLA models, depending upon the interaction effect from the repeated measures ANOVA (α=.05). Results For angle analysis, the incisor group demonstrated a significant difference between the natural tooth and SLA die on the buccolingual surfaces (PPPPPP Conclusions For the comparison of angles, SLA dies did not replicate the subgingival contour of natural teeth on the buccolingual surfaces of the incisal groups. For the comparison of length and volume, SLA dies were more concave and did not replicate the subgingival contour of natural teeth in the incisal and molar groups

Selective Laser Sintering of Zirconia with Micro-Scale Features

Recent work in Selective Laser Sintering of ceramics at the University of Texas at Austin demonstrates the capability to produce zirconia parts with fine features. Zirconia powder was pre-processed into spherical particles, laser sintered with a sacrificial polymer binder, infiltrated and post-sintered to higher density. Optical micrographs show that hole sizes of 180 /-tm are possible in fully ceramic components.Mechanical Engineerin

Molecular Dynamics Simulation of Ga Penetration along Grain Boundaries in Al: a Dislocation Climb Mechanism

Many systems where a liquid metal is in contact with a polycrystalline solid exhibit deep liquid grooves where the grain boundary meets the solid-liquid interface. For example, liquid Ga quickly penetrates deep into grain boundaries in Al, leading to intergranular fracture under very small stresses. We report on a series of molecular dynamics simulations of liquid Ga in contact with an Al bicrystal. We identify the mechanism for liquid metal embrittlement, develop a new model for it, and show that is in excellent agreement with both simulation and experimental data