• Journal of Korean Society of Environmental Engineers
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• v.35 no.9
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• pp.630-635
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• 2013

There is a need to establish systematic procedure of groundwater quality standards, however, there were no specified basis for establishing substances and values in Korean groundwater quality standards for non-drinking water. In this study, we reviewed basis for deriving groundwater quality standard in the developed countries, considering carcinogenic and non-carciongenic risk via inhalation and dermal contact exposure pathways. Also, we reviewed the prior systematic procedure of standards related to water quality (e.g. drinking water, surface water, and wastewater). USEPA RAGS, ASTM RBCA, and Massachusettes presented the formulas for deriving groundwater concentrations of chemicals and there were similarity and differences. We suggests systematic procedure of groundwater quality standards, as follows. (1) Selection of groundwater pollutants population, (2) Possibility of risk assessment, (3) Selection of monitoring priority substances, (4) Monitoring, (5) Risk assessment, (6) Selection of groundwater quality standard candidates, (7) Selection of new substances and values for groundwater quality standards. Especially, groundwater concentration of hazardous material were presented according to revised risk formulas via inhalation and dermal contact.

• Korean Journal of Food Science and Technology
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• v.42 no.4
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• pp.390-397
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• 2010

Residual solvents in foods are defined as organic volatile chemicals used or produced in manufacturing of extracts or additives, or functional foods. The solvents are not completely eliminated by practical manufacturing techniques and they also may become contaminated by solvents from packing, transportation or storage in warehouses. Because residual solvents have no nutritional value but may be hazardous to human health, there is a need to remove them from the final products or reduce their amounts to below acceptable levels. The purpose of this study was to develop and evaluate an analytical method for the screening of residual solvents in health functional foods. Furthermore, the aim of this study was to constitute a reasonable management system based on the current state of the market and case studies of foreign countries. Eleven volatile solvents such as MeOH, EtOH, trichloroethylene and hexane were separated depending on their column properties, temp. and time using Gas Chromatography (GC). After determining the GC conditions, a sample preparation method using HSS (Head Space Sampling) was developed. From the results, a method for analyzing residual solvents in health functional foods was developed considering matrix effect and interference from the sample obtained from the solution of solvents-free health functional foods spiked with 11 standards solutions. Validation test using the developed GC/HSS/MS (Mass Spectrometry) method was followed by tests for precision, accuracy, recovery, linearity and adequate sensitivity. Finally, examination of 104 samples grouped in suits was performed by the developed HSS/GC/MS for screening the solvents. The 11 solvents were isolated from health functional foods based on vapor pressure difference, and followed by separation within 15 minutes in a single run. The limt of detection (LOD), limit of quantification (LOQ), recovery and coefficient of variation (C.V.) of these compounds determined by the HSS/GC/MS were found to be 0.1 pg/mL, 0.1-125 pg/g, 51.0-104.6%, and less than 15%, respectively. Using the developed HSS/GC/MS method, residual solvent from 16 out of 104 health functional products were detected as a EtOH. This method therefore seems t o be a valuable extension ofanalytical method for the identification of residual solvents in health functional food.

• Korean Journal of Ecology and Environment
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• v.44 no.4
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• pp.347-357
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• 2011

We examined two reservoirs (Inkyung res. and Joongang res.) and two streams (Kyungan str. and Jecheon str.), all of which were eutrophic, during the 2010 warm season, to evaluate the water quality improvement activity (WQIA) of plant-mineral composite (PMC), which was previously developed to control suspended solids, including cyanobacterial bloom (Kim et al., 2010). We simultaneously measured both solid (S-MCLR) and dissolved microcystin-LR (D-MCLR), before and after PMC treatment, in the Joongang reservoir. Taking water body size and volume into account, we conducted the whole-scale experiment in the Inkyung reservoir, and mesocosm-scale experiments in the other three systems. The WQIAs of PMC were found to be comparatively high in SS (70~81%), TP (75~91%), BOD (65~91%), Chl-a (88~98%), phytoplankton (84~92%) and zooplankton (68~88%), except for the Kyungan stream, which was below 45% in all parameters. After PMC treatment, the concentrations of both SMCLR (47%) and D-MCLR (96%) decreased within two days, suggesting a mitigation possibility of hazardous chemicals such as agrochemicals and endocrine disrupters in the aquatic ecosystem. Our results collectively indicate that PMC is a useful agent to control suspended solids, including nuisance cyanobacterial bloom and their exudates, in an undisturbed water system with a long residence time.

• Journal of Food Hygiene and Safety
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• v.25 no.2
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• pp.148-152
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• 2010

Domestic studies for identification of causality between children exposure to toxic chemicals, such as arsenic (As) and resulted hazardous effects were not implemented. This study was conducted to probabilistically estimate dietary As intake and health risk assessment for young children and all age-specific populations from the consumption of As-contaminated rice of Korea. Arsenic intakes for young children (1 to 6 years old) from As-contaminated rice were higher than other age-specific groups, based on a dose-per-body weight basis. Based on the current EPA cancer slope factor for As, estimated cancer risks (to the skin cancer) associated with dietary intake of As-contaminated rice for 1 to 2 years old group and 3 to years old group are 1.76 per 10,000 and 3.16 per 10,000, respectively, at the 50th percentile. Based on possible reference levels (0.005 mg/kg/day) for children, mean and $95^{th}$ percentile value of HQ from rice for young children are very below 1.0, which is a regulatory limit of non-carcinogenic risks for human.

• Korean Journal of Ecology and Environment
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• v.44 no.2
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• pp.103-112
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• 2011

Aquatic contamination by organic pollutants has been a suspected reason for rapid decrease of amphibian populations whose embryonic and larval stages are in an aquatic environment. Amphibian embryos can be a useful model to study the ecoctoxicologial impacts of aquatic pollutants. The obtained toxicological data are useful references for the management of aquatic pollutants in public health because amphibia share many developmental events with terrestrial vertebrates including humans. Safety guidelines for the toxicological effects of aquatic contaminants of chemicals identified as hazardous should be addressed at multiple endpoints. Alkylphenols have been widely-used in agricultural, industrial, and household activities; they contaminate and can persist in aquatic environments. Exposure to alkylphenols results in endocrine disruption in aquatic animals. In this review, we summarize the developmental toxicities of alkylphenols in amphibian embryos and larva according to the exposure route, chemical concentration, duration of exposure, and affected developmental stage together with mechanisms of toxicity and typical patterns of developmental abnormality. The merits of amphibian embryos as a toxicity test model for mid- to long-term exposure to aquatic pollutants are discussed proposed.

• Journal of the Microelectronics and Packaging Society
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• v.26 no.4
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• pp.163-169
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• 2019

Sn-Pb solder alloys in electronics rapidly has been replaced to Pb free solder alloys because of various environmental regulations such as restriction of hazardous substances directive (RoHS), European Union waste electrical, waste electrical and electronic equipment (WEEE), registration evaluation authorization and of chemicals (REACH) etc. Because Sn58%Bi (in wt.%) solder alloy has low melting point and higher mechanical properties than that of Sn-Pb solder, it has been studied to manufacture electronic components. However, the reliability of Sn58%Bi solder could be lowered because of the brittleness of Bi element included in the solder alloy. Therefore, we observed the microstructures of Sn58%Bi composite solders with various contents of Sn-decorated multiwalled carbon nanotube (Sn-MWCNT) particles and evaluated bonding strength of the FR-4 components assembled with Sn58%Bi composite solder. Also, microstructures and bonding strengths of the Sn58%Bi composite solder joints were evaluated with the number of reflows from 1 to 7 times, respectively. Bonding strengths and fracture energies of the Sn58%Bi composite solder joints were measured by die shear test. Microstructures and fracture modes were observed with scanning electron microscope (SEM). Microstructures in the Sn58%Bi composite solder joints were finer than that of only Sn58%Bi solder joint. Bonding strength and fracture energy of Sn58%Bi composite solder including 0.1 wt.% of Sn-decorated MWCNT particles increased up to 20.4% and 15.4% at 5 times in reflow, respectively.

• Journal of Korean Society of Forest Science
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• v.106 no.1
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• pp.70-76
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• 2017

Among the forest road pavement methods, the majority of current constructions utilize concrete pavements but it has disadvantages as follows: many cracked concrete pavements generated by the erosion of underlying soil layers, could not be used as forest roads in steep slope during winter, and cement contains hazardous chemicals (hexavalent chromium, etc.). In order to supplement the limitations of the use of concrete pavement, this study was conducted to investigate the operation process and cost, the strength and compaction of the experimental forest road pavement(85 m) utilizing eco-friendly solidification material at Goryeong-gun, Gyeongsangbuk-do. The work elements of experimental forest road paving were classified into: preparation, Roadbed excavation, Roadbed grading, subgrade compaction, form work, collection and selection of site soil, mixing site soil and eco-friendly solidification material, paving by eco-friendly solidification material, compaction by vibrating roller and curing. The result of economic analysis using construction cost shows that for concrete costs total to $38,681won/m^3$ while for the eco-friendly paving material it is $38,245won/m^3$. Thus the construction costs for concrete and the eco-friendly paving material are similar. And the results of the Schmidt Hammer test for strength analysis by curing period are 10.5-13.5 MPa for 7 days, 18.1-22.7 MPa for 14 days, and 20.8-23.0 MPa for 28 days.

• Journal of Korean Society of Environmental Engineers
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• v.34 no.3
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• pp.168-176
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• 2012

A total of 48 dust samples were collected from large shopping mall parking lots in Daegu metropolitan city in March 2011. Samples were sieved through a 100 ${\mu}m$ mesh and the concentration of 14 elements have been determined using by ICP after acid extraction. Results showed that Ca, Fe, K, Mg, Mn, Na and V were affected by natural sources while Cd, Cr, Cu, Ni, Pb and Zn were affected by anthropogenic sources. The measured values were remarkably higher in components from natural sources than in components from anthropogenic sources. Anthropogenic trace element concentrations of ground roof dust were higher than those of ground and underground indoor dust. A large percentage of trace elements came from natural sources rather than anthropogenic sources. The percentage composition of chemicals of ground roof dust were higher than those of ground and underground indoor dust. This study showed that investigated parking lots were rarely contaminated with hazardous heavy metals. The heavy metal pollution of ground roof were higher than those of ground and underground indoors. The correlation analysis among trace elements suggest that components in ground roof were more highly correlated than those in ground and underground indoor. Also anthropogenic trace element levels were well correlated with parking lot age and parking density.

• Safety and Health at Work
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• v.7 no.1
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• pp.63-71
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• 2016

Background: Construction painters have not been studied well in terms of their hazards exposure. The objective of this study was to evaluate the exposure levels of total volatile organic compounds (TVOCs) for painters in the construction industry. Methods: Activity-specific personal air samplings were carried out in three waterproofing activities [polyurethane (PU), asphalt, and cement mortar] and three painting activities (epoxy, oil based, and water based) by using organic-vapor-monitor passive-sampling devices. Gas chromatograph with flame ionization detector could be used for identifying and quantifying individual organic chemicals. The levels of TVOCs, by summing up 15 targeted substances, were expressed in exposure-index (EI) values. Results: As arithmetic means in the order of concentration levels, the EIs of TVOCs in waterproofing works were 10.77, 2.42, 1.78, 1.68, 0.47, 0.07, and none detected (ND) for indoor PU-primer task, outdoor PU-primer task, outdoor PU-resin task, indoor PU-resin task, asphalt-primer task, asphalt-adhesive task, and cement-mortar task, respectively. The highest EI for painting works was 5.61 for indoor epoxyprimer task, followed by indoor epoxy-resin task (2.03), outdoor oil-based-spray-paint task (1.65), outdoor water-based-paint task (0.66), and indoor oil-based-paint task (0.15). Assuming that the operations were carried out continuously for 8 hours without breaks and by using the arithmetic means of EIs for each of the 12 tasks in this study, 58.3% (7 out of 12) exceeded the exposure limit of 100% (EI > 1.0), while 8.3% (1 out of 12) was in 50e100% of exposure limit (0.5 > EI > 1.0), and 4 tasks out of 12 were located in less than 50% of the limit range (EI < 0.5). Conclusion: From this study, we recognized that construction painters are exposed to various solvents, including carcinogens and reproductive toxins, and the levels of TVOC concentration in many of the painting tasks exceeded the exposure limits. Construction workers need to be protected from chemical agents during their painting works by using personal protective devices and/or work practice measures. Additional studies should focus on the exposure assessment of other hazards for construction workers, in order to identify high-risk tasks and to improve hazardous work environments.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.4
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• pp.718-725
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• 2017

A liquid storage tank is one of the most important structures in industrial complexes dealing with chemicals, and its structural damage due to an earthquake may cause a disastrous event such as the leakage of hazardous materials, fire, and explosion. It is thus essential to assess the seismic fragility of liquid storage tanks and prepare for seismic events in advance. When a liquid storage tank is oscillated by a seismic load, the hydrodynamic pressure caused by the liquid-structure interaction increases the stress and causes structural damage to the tank. Meanwhile, the seismic fragility of the structure can be estimated by considering the various sources of uncertainty and calculating the failure probabilities in a given limiting state. To accurately evaluate the seismic fragility of liquid storage tanks, a sophisticated finite element analysis is required during their reliability analysis. Therefore, in this study, FERUM-ABAQUS, a recently-developed computational platform integrated with commercial finite element and reliability analysis software packages, is introduced to perform the finite element reliability analysis and calculate the failure probability of a liquid storage tank subjected to a seismic load. FERUM-ABAUS allows for automatic data exchange between these two software packages and for the efficient seismic fragility assessment of a structure. Using this computational platform, the seismic fragility curve of a liquid storage tank is successfully obtained.