• Journal of the Korea Convergence Society
• /
• v.10 no.12
• /
• pp.257-262
• /
• 2019

Recently, the number of people enjoying various leisure sports has increased. As a result, the vehicles with various items loaded onto the roof can be easily seen on the street. The device that enables loading on the vehicle roof is called by a rack, and each vehicle has its own different shape. There are various types of roof racks but they must have the strength and durability to load heavy loads. In this study, the structural analysis was performed according to the support method of the roof rack and the shape of the fixture. Of three models, it was shown that model C had the best durability. Therefore, this study result shows which shape of the roof rack is most stable among the models. By utilizing the design data about a convergence study through the structural analysis due to the shape of automotive roof rack obtained on the basis of this result, the esthetic feeling can be shown by being converged onto the part of automobile at actual life.

• Journal of the Korean Society of Groundwater Environment
• /
• v.4 no.1
• /
• pp.41-53
• /
• 1997

Geochemical data of soil and water samples were presented in order to assess the environmental impart for drinking water sites. Microscopic observation of rock samples and physical and chemical analysis of soil and water samples were undertaken. The geology of study areas are classified into three groups such as granitic rocks, meta-sedimentary rocks and sedimentary rocks. Enrichment of heavy metals derived from those rocks is not found in this study areas. Soils were analyzed for Cu, Pb, Zn, Cd and Cr using AAS extracted by HNO$_3$+HClO$_4$ and 0.1 N HCl. Heavy metal concentrations in soils are within the range of those in uncontaminated soils. In comparison of metal contents extracted by 0.1 N HCl and HNO$_3$+HC1O$_4$, less than 10% of the heavy metals are present in the exchangeable fraction. In particular, an pollution index has been proposed to assess the degree of soil contamination. Pollution index in soils are between 0.03 and 0.47 therefore, soils are not polluted with heavy metals. Deep groundwaters within granitic rocks have been evolved into Na$\^$＋/-HCO$_3$$\^$-/ type, whereas other deep groundwaters evolved into Ca$\^$2＋/-HCO$_3$$\^$-/ type. The predominance of Na$\^$＋/ over Ca$\^$2＋/ in deep groundwaters within granitic rocks is a result of dissolution of plagioclase, but for sedimentary and meta-sedimentary rocks, dissolution of calcite is a dominant factor for their hydrogeochemistry. The pH, conductivity and contents of the most dissolved ions in the water increase with depth. Shallow groundwaters, however, are highly susceptible to pollution owing to agricultural activities, considering the fact that high contents of nitrate, chloride and potassium, and high K/Na ratio are observed in some shallow groundwaters. In a thermodynamic approach, most natural water samples are plotted within the stability fields of kaolinite and smectite. Therefore, microcline and other feldspars will alter to form clay minerals, such as kaolinite and smectite. From the modelling for water-rock interactions based on mass balance equation, models accord well with behavior of the ions and results of thermodynamic studies are derived.

• Journal of Wetlands Research
• /
• v.6 no.1
• /
• pp.133-147
• /
• 2004

Environmental quality(water and sediment) was analyzed in the tidal flat of Saemangum of Jeonbuk Province, the west coast of Korea, using the 101 sediment samples and 69 water samples collected in September 4~13, 2001. Major water quality parameters with the means of 69 surface water samples are as follows; $25.51{\pm}0.68^{\circ}C$ for water temperature, $29.88{\pm}5.01$ for salinity, $1.40{\pm}0.78mg/L$ for COD, $0.352{\pm}0.417mg/L$ for DIN, and $0.027{\pm}0.023mg/L$ for phosphate, respectively. Higher values were found at the subestuary of Dongjin and Mangyung River, and lower values at the Saemangum embayment and Gomso Bay. There was a significant negative correlation between salinity and the other water quality parameters(p<0.0001) such as COD, nutrients, SS and N/P. This correlation suggested that the major pollution sources be from terrestrial inputs through tributaries in this area. Principal component analysis clearly revealed a spatial variation of water quality; stations with higher values of nutrients and COD located subestuary of tributaries. 14 sediment quality parameters including 8 trace metals were measured using the 101 surface sediment samples. Average values for the parameters are as follows; Al $2.28{\pm}0.92%$, Cd $0.61{\pm}0.27ppm$, Cu $8.95{\pm}4.06ppm$, Fe $1.19{\pm}0.37%$, Mn $182.31{\pm}77.45ppm$, Ni $10.83{\pm}4.97ppm$, Pb $15.20{\pm}4.35ppm$, Zn $41.34{\pm}34.62ppm$, COD $2.68{\pm}1.85mg/g\;dry$, AVS $0.04{\pm}0.08mg/g\;dry$, IL $1.29{\pm}1.08%$, water content $24.11{\pm}4.49%$, TN $0.02{\pm}0.02%$, TC $0.22{\pm}0.30%$. Spatial variations of sediment quality were not clear as water quality. Some higher values were found at the subestuary of Gum River and lower values at the other area. There was a significant positive correlation between the heavy metal concentrations and organic materials within the sediment(p<0.05). Enrichment factors showed the ranges of 1~2 for most of the metals in the sediment except zinc(1~6), indicating no serious exogenous input of heavy metals in the study area. Also, the heavy metal concentrations in the sediment were within the ranges found at the natural marine environments.

• Journal of Soil and Groundwater Environment
• /
• v.12 no.4
• /
• pp.16-24
• /
• 2007

An investigation on the polluted sediments in the Lake Sihwa and the benthos that inhabited on the sediments was conducted. Cost effective remediation alternatives were derived form the results of the investigation. The sediment samples taken from four sampling points out of thirteen showed relatively high heavy metal (particularly copper) concentrations which exceeded the Effects Range Low (ERL) of the National Oceanic and Atmospheric Administration, USA. The four sampling points were located in front of industrial complexes. Although the heavy metals appeared to have affected the growth of the benthos, the concentration of it did not exceed the criteria of dredging that were developed by Netherlands or the State of Washington, USA. However, contamination by organic matters and sulfur compounds was severe, which exceeded the criteria of dredging that were established in Japan. The sediments taken from the four sampling points which were contaminated with heavy metals showed higher organic matter content in general. The organic matters in the sediments depleted oxygen in summer, which appeared to be fatal to the benthos. A comprehensive analysis on the sediments, benthos, and other environmental impact from the contaminated sediments drew a conclusion that the benthonic environment of the Lake Sihwa needed a stepwise remediation, giving a particular emphasis on the clean up of the sediments upstram of the Lake which could cause odor problems to the nearby residential area.

• Journal of Environmental Health Sciences
• /
• v.44 no.3
• /
• pp.283-292
• /
• 2018

Objectives: This study was conducted to identify hazardous factors that reflect the characteristics of the academy and to provide basic data of environmental safety standard. Methods: Heavy metals, volatile organic compounds, formaldehyde, pesticides and phthalates were measured in 20 academies, which were supplementary, music, art and physical education institutes. Results: In case of heavy metals, the 12 locations were detected for lead (Pb) over the standard value, and 15 locations were exceeded for the total heavy metal. In six locations, the concentrations of volatile organic compounds were exceeded the standard value of $400{\mu}g/m^3$, and two locations for formaldehyde were exceeded the standard value of $100{\mu}g/m^3$. The most commonly detected agents in the air dust were chlorpyrifos and diazinon. The concentrations of DEHP, DINP, and DBP were detected and exceeded in several academies, The risk assessment results showed that HCHO as carcinogen had a safety level of 10-7 to 10-6, and DEHP and DINP as non-carcinogens had a safety level as assessed to be under than 0.1. Conclusions: Through the investigation of long-term environmental and health effects related laws on academies, indoor air quality management might be needed because there were cases of exceeding standard.

• Analytical Science and Technology
• /
• v.13 no.2
• /
• pp.258-267
• /
• 2000

The result of five year's experience on Inter-laboratory Comparison for Analyses of Heavy Metals and Organic Solvent Metabolites in Biological Samples was described. Since 1995, around a hundred laboratories in the Occupational Health have participated this program twice per year by the Industrial Safety and Health Law. Four metals in blood and five organic solvent metabolites in urine were examined. Reference samples were made by spiking standard materials to human blood or urine pools treated previously to give homogeneity and stability for a specific time periods. Some reference samples for organic solvent metabolites were made from workers' urine who were exposed to the organic solvents. Some items such as Lead in blood and Hippuric acid in urine showed good accordance between participants while the other items such as Mercury and N-methylformamide in urine showed poor proficient rate. The results were published in the internet or newspaper to help the consumer of the laboratory's service to get the information on them and to make competition between them. The inter-laboratory's comparison program have done greate role to improve the ability of analysis and reliability of analytical data produced from each laboratory.

• Journal of Environmental Health Sciences
• /
• v.50 no.1
• /
• pp.25-35
• /
• 2024

Background: There are concerns about the health effects of various environmental pollution exposures among residents living near coal-fired power plants (CFPP). Objectives: This study attempted to compare the concentrations of heavy metals in blood and urine and those of urinary volatile organic compound (VOC) metabolites according to the residential separation distance. Methods: Participants in the study totaled 334 people who have lived for more than 10 years in areas within 10 km of a CFPP. The separation distance was analyzed in quartiles by dividing it into Q1 (88 people), Q2 (89 people), Q3 (89 people), and Q4 (68 people). We explained the purpose of this study to the participants and collected blood and urine after obtaining signatures on a participation agreement. Results: The study participants were 102 males (30.5%) and 232 females (69.5%), with an average age of 71. The average length of residence and distance were 43.8 years and 4,800 meters. The geometric mean concentrations of Pb, Cd, and Hg in blood and As and Cd in urine were respective 1.35 ㎍/dL, 1.43 ㎍/L, 3.16 ㎍/L. They were 167.88 ㎍/g for creatinine and 1.58 ㎍/g creatinine. The metabolite concentrations of VOCs were 50.67 ㎍/g creatinine in t, t-muconic acid (t, t-MA), 10.73 ㎍/g creatinine in benzyl mercapturic acid, 317.05 ㎍/g creatinine in phenylglyoxylic acid, 123.55 ㎍/g creatinine in methylhippuric acid, and 190.82 ㎍/g creatinine in mandelic acid. The concentration of Pb in the blood and Cd and t, t-MA in the urine of residents within affected area of the CFPP showed statistically significant differences among distance groups. Conclusions: The concentration of urinary VOCs metabolites, especially t, t-MA, differed according to the distance groups of residents within the affected area of CFPP (p<0.05).

• Composites Research
• /
• v.29 no.3
• /
• pp.111-116
• /
• 2016

The tilting pad journal bearing for the turbo compressor application has a role to support high speed and heavy loading rotor. White metal has been widely used for the bearing material but the conventional bearing is immediately suspended and induces serious serious damage to the rotor under the unexpected oil cut situation or the insufficient oil film formation. The carbon fiber reinforced composite having high specific stiffness, specific strength and excellent tribological characteristics can solve these seizure problems. In this work, the study on the durability of high thermal resistance carbon fiber/epoxy composite tilting pad journal bearing under oil cut situation was conducted. The material properties of the composite materials including tensile, compressive and interlaminar properties were measured at room and high temperature of oil cut situation. To investigate the possibility of failure of composite tilting pad journal bearing under oil cut situation, the stress distribution of the composite bearing was analyzed via finite element analysis and the Tsai-Wu Failure index was calculated. To verify the failure analysis results, the oil cut tests for the composite tilting pad journal bearing were conducted using industrial test bench.

• Journal of Korean Society of Environmental Engineers
• /
• v.31 no.9
• /
• pp.735-742
• /
• 2009

The bone of spinal animals has a hydroxylapatite ($Ca_{10}(PO_4)_6(OH)_2$, HAp) structure which is well known as an excellent inorganic ion exchanger for various heavy metal ions in solutions. In this study, the reusability of cow-bone, pig-bone and fish-bone as a potential material for the removal of heavy metals in solutions was evaluated from the removal of Cu(II) ion in batch tests. The surface properties of three bones, calcined at different temperatures, were measured with SEM, XRD, FT-IR analyses. From the SEM analysis, a clear development of heterogeneity as well as pores having small diameter was observed as the calcination temperature increased. The results of X-ray diffraction analysis showed well developed crystallinity on the surface of calcined bones obtained at higher temperatures, suggesting a transform of amorphous type to crystalline type. Fourier transform infrared (FT-IR) analysis showed disappearance of water molecule on the surface of HAp and organic functional groups of the HAp with increasing the calcination temperatures. Cu(II) removal in the control test was below 15%. By the way, additional 40% increase of Cu(II) removal was observed in the presence of calcined bones. For three bones, Cu(II) removal was decreased as the calcined temperature increased. Cu(II) removal was increased as the solution pH increased due to a favorable condition for the cation exchange as well as precipitation.

• Environmental Analysis Health and Toxicology
• /
• v.30
• /
• pp.4.1-4.11
• /
• 2015

Objectives: This survey was designed to conduct the first nationwide dietary exposure assessment on hazardous substances including the intakes of functional food and herbal medicine. In this paper, we introduced the survey design and the results of the dietary exposure status and internal exposure levels of lead (Pb), cadmium (Cd), and mercury (Hg). Methods: We selected 4867 subjects of all ages throughout Korea. We conducted a food survey, dietary survey, biomonitoring, and health survey. Results: Pb and Cd were the highest (median value) in the seaweed ($94.2{\mu}g/kg$ for Pb; $594{\mu}g/kg$ for Cd), and Hg was the highest in the fish ($46.4{\mu}g/kg$). The dietary exposure level (median value) of Pb was $0.14{\mu}g/kg$ body weight (bw)/d, $0.18{\mu}g/kg$ bw/d for Cd, and $0.07{\mu}g/kg$ bw/d for Hg. Those with a blood Pb level of less than $5.00{\mu}g/dL$ (US Centers for Disease Control and Prevention, reference value for those 1 to 5 years of age) were 99.0% of all the subjects. Those with a blood Cd level with less than $0.30{\mu}g/L$ (German Federal Environmental Agency, reference value for non-smoking children) were 24.5%. For those with a blood Hg level with less than $5.00{\mu}g/L$ (human biomonitoring I, references value for children and adults, German Federal Environmental Agency) was 81.0 % of all the subjects. Conclusions: The main dietary exposure of heavy metals occurs through food consumed in a large quantity and high frequency. The blood Hg level and dietary exposure level of Hg were both higher than those in the European Union.