• Journal of Environmental Policy
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• v.7 no.1
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• pp.53-79
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• 2008

In this study, we conducted a comprehensive study to analyze the environmental behavior of airborne Ni for the proper establishment of basic control tactics based on the metal concentration data sets collected from the major cities in Korea for the 14 year period(1991 through 2004). The mean concentration of Ni determined from all cities during the entire study period varied from as little as 7.38+6.70 ng $m^3$(Won Ju) to the maximum of 41.4+26.2 ng $m^3$ in a highly industrialized city of An San. However, the mean concentrations of Ni from most cities generally fell in the range of 10 to 20 ng $m^3$. When the Ni concentration data in all cities are compared between the former half(1991 to 1997) and the latter half period(1998 to 2004), a reduction in its concentration levels was seen dominantly between the two study period. Comparison of seasonal patterns generally indicated the enhanced concentrations of Ni during spring/winter relative to summer/fall term. The overall results of this study suggest that the source processes of Ni are diverse enough to exhibit moderately diverse patterns between different cities. Considering that relative enhancement in Ni levels is observed from most of industrial and/or large scale cities, a development of adequate control tactics for Ni is highly desirable.

• Journal of Periodontal and Implant Science
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• v.48 no.3
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• pp.152-163
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• 2018

Purpose: To determine whether the swelling and mechanical properties of osmotic self-inflating expanders allow or not the induction of intraoral soft tissue expansion in dogs. Methods: Three different volumes (0.15, 0.25, and 0.42 mL; referred to respectively as the S, M, and L groups) of soft tissue expanders (STEs) consisting of a hydrogel core coated with a silicone-perforated membrane were investigated in vitro to assess their swelling behavior (volume swelling ratio) and mechanical properties (tensile strength, tensile strain). For in vivo investigations, the STEs were subperiosteally inserted for 4 weeks in dogs (n=5). Soft tissue expansion was clinically monitored. Histological analyses included the examination of alveolar bone underneath the expanders and thickness measurements of the surrounding fibrous capsule. Results: The volume swelling ratio of all STEs did not exceed 5.2. In tensile mode, the highest mean strain was registered for the L group ($98.03{\pm}0.3g/cm$), whereas the lowest mean value was obtained in the S group ($81.3{\pm}0.1g/cm$), which was a statistically significant difference (P<0.05). In addition, the S and L groups were significantly different in terms of tensile strength ($1.5{\pm}0.1g/cm$ for the S group and $2.2{\pm}0.1g/cm$ for the L group, P<0.05). Clinical monitoring showed successful dilatation of the soft tissues without signs of inflammation up to 28 days. The STEs remained volumetrically stable, with a mean diameter in vivo of 6.98 mm, close to the in vitro post-expansion findings (6.69 mm). Significant histological effects included highly vascularized collagen-rich fibrous encapsulation of the STEs, with a mean thickness of $0.67{\pm}0.12mm$. The bone reaction consisted of resorption underneath the STEs, while apposition was observed at their edges. Conclusions: The swelling and mechanical properties of the STEs enabled clinically successful soft tissue expansion. A tissue reaction consisting of fibrous capsule formation and bone loss were the main histological events.

• Journal of the Korean Geosynthetics Society
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• v.14 no.1
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• pp.43-50
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• 2015

Lightweight Foamed Soil (LWFS) is a useful material for underground pipe backfill because of reusability of excavated soil and no compaction effect. In this research, a pilot test is carried out and monitoring results are analyzed to investigate behaviors of a flexible pipe, when LWFS is applied as a backfill material. Simultaneously, they are compared with another test case which is backfilled with Saemangeum dredged soil. As a result, the vertical earth pressure of the case backfilled with LWFS slurry presents that decreases as much as 25.6% in comparison with dredged soil and it is only within 10% after solidification. In case backfilled with dredged soil, the horizontal earth pressure is more than 3.6 times of the case used by LWFS and the vertical and horizontal deformation is more than 3.2 and 2.6 times of the case, respectively. It presents excellent effects on earth pressure and deformation reduction of LWFS. The stresses measured at the upper side of the pipe generally present compressive aspects in case backfilled with dredged soil. However, they present tensile aspects in case of LWFS. It is because of negative moment occurred at the center of the pipe due to the buoyancy from LWFS slurry. Conclusively, LWFS using Saemangeum dredged soil is very excellent material to use near the area in comparison with the dredged soil. However, the countermeasure to prevent the buoyancy is required.

• Applied Chemistry for Engineering
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• v.29 no.5
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• pp.510-518
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• 2018

Recently, lots of interests have been concentrated on the scrubber system that abates waste gases produced from semiconductor manufacturing processes. An effective design of the thermal decomposition reactor inside a scrubber system is significantly important since it is directly related to the removal performance of pollutants and overall stabilities. In the present study, a computational fluid dynamics (CFD) analysis was conducted to figure out the thermal and flow characteristics inside the reactor of wet scrubber. In order to verify the numerical method, the temperature at several monitoring points was compared to that of experimental results. Average error rates of 1.27~2.27% between both the results were achieved, and numerical results of the temperature distribution were in good agreement with the experimental data. By using the validated numerical method, the effect of the reactor geometry on the heat transfer rate was also taken into consideration. From the result, it was observed that the flow and temperature uniformity were significantly improved. Overall, our current study could provide useful information to identify the fluid behavior and thermal performance for various scrubber systems.

• Asian Pacific Journal of Cancer Prevention
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• v.14 no.11
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• pp.6807-6812
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• 2013

Background: Lung cancer is a major cause of Korean female mortality and is clearly associated with smoking. The Korean National Health and Nutrition Examination Survey (KNHANES IV-2,3), which included both self-reports of smoking and urinary cotinine data, revealed a significant discrepancy between the prevalence of self-reported and biochemically-verified female smokers. The factors associated with accurate self-reporting of current smoking status remain poorly understood, however. Materials and Methods: We assessed the prevalence of smoking in KNHANES using both self-report and urinary cotinine data. Subsequently, using univariate and multivariate tests, we assessed whether age, intensity of smoking, marital status, relationship with cohabitants, education, occupation, residential area, or annual household income were associated with inaccurate self-reporting in Korean females. We also investigated whether the prevalence of inaccurate self-reports changed over the survey period, 2008-2009. Results: The prevalence of self-reported smoking was 47.8% in males and 6.6% in females. By contrast, the prevalence of smoking as assessed by urinary cotinine levels was 52.2% in males and 14.5% in females. Of the 746 females with urinary cotinine levels >50ng/ml, 407 (56.0%) provided inaccurate self-reports. In a multivariate model, age group(40-49: OR 3.54, 95%CI 1.42-8.86, p=0.007; ref :20-29), cotinine intensity(OR 0.999, 95%CI 0.998-0.999, p<0.001), marital status (married but without spouse: OR 0.37, 95%CI 0.15-0.94, p=0.037; ref :never married), relationship with cohabitants (living with a spouse and unmarried child: OR 2.63, 95%CI 1.44-4.80, p=0.002; living with 2 generations except unmarried child: OR 2.53, 95%CI 1.09-5.87, p=0.030; living with ${\geq}3$ generations: OR 3.25, 95%CI 1.48-7.10, p=0.003; ref :spouse only) and education(college or higher: OR 2.73, 95%CI 1.04-7.18, p=0.042; ref :elementary or less) were independently associated with inaccurate self-reports. Conclusions: The trend of smoking prevalence of Korean females is likely to decrease. However, an elevated prevalence of inaccurate self-reports by females remains. Factors related to the intensity of smoking and family status appear to influence whether a Korean female provides an accurate self-report when asked about smoking behavior.

• Spatial Information Research
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• v.16 no.3
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• pp.279-290
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• 2008

Landslide, one of the serious natural disasters, has Incurred a large loss of human and material resources. Recently, many forecasting or alarm systems based on various kinds of measuring equipment have been developed to reduce the damage of landslide. However, only a few of these equipments are guaranteed to evaluate the safety of whole side of land slope with their accessibility to the slope. In this study, we performed some experiments to evaluate the applicability of a terrestrial LiDAR as a surveying tool to measure the displacement of a land slope surface far a slope collapsing protection system. In the experiments, we had applied a slope stability method to a land slope and then forced to this slope with a load increasing step by step. In each step, we measured the slope surface with both a total station and a terrestrial LiDAR simultaneously. As the result of Slope Fracturing analysis using all targets, the LiDAR system showed that three was 1cm RMSE on X-axis, irregularity errors on Y-axis and few errors on Z-axis compare with Total Station. As the result of Slope Fracturing analysis using continuous targets, the pattern of Slope Fracturing was different according to the location of continuous targets and we could detect a continuous change which couldn't be found using Total station. The accuracy of the LiDAR data was evaluated to be comparable to that of the total station data. We found that a LiDAR system was appropriate to measuring the behaviour of land slope. The LiDAR data can cover the whole surface of the land slope, whereas the total station data are available on a small number of targets. Moreover, we extracted more detail information about the behavior of land slope such as the volume and profile changes using the LiDAR data.

• Economic and Environmental Geology
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• v.40 no.1 s.182
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• pp.29-45
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• 2007

Biogeochemical characteristics involving redox processes in groundwater from a riverine alluvial aquifer was investigated using multi-level monitoring wells (up to 30m in depth). Anaerobic conditions were predominant and high Fe ($14{\sim}37mg/L$) and Mn ($1{\sim}4mg/L$) concentrations were observed at 10 to 20 m in depth. Below 20 m depth, dissolved sulfide was detected. Presumably, these high Fe and Mn concentrations were derived from the reduction of Fe- and Mn-oxides because dissolved oxygen and nitrate were nearly absent and Fe and Mn contents were considerable in the sediments. The depth range of high Mn concentration is wider than that of high Fe concentration. Dissolved organics may be derived from the upper layers. Sulfate reduction is more active than Fe and Mn reduction below 20 m in depth. Disparity of calculated redox potential from the various redox couples indicates that redox states are in disequilibrium condition in groundwater. Carbonate minerals such as siderite and rhodochrosite may control the dissolved concentrations of Fe(II) and Mn(II), and iron sulfide minerals control for Fe(II) where sulfide is detected because these minerals are near saturation from the calculation of solubility equilibria.

• Explosives and Blasting
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• v.33 no.3
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• pp.21-28
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• 2015

The objective of this study is to develop a method for monitoring continuously the combustion propagation behavior of commercial thermite reaction mixtures using conventional continuous VOD (velocity of detonation) system. In order to monitor the combustion front propagation with elapsed time during thermite reaction, the VOD system employs two types of commercial VOD probes and one self-made probe: VOD PROBEROD-OS, VOD PROBEROD-HS and VOD PROBEROD-ES, respectively. Among the probes, the only self made VOD PROBEROD-ES successfully demonstrates the velocity of combustion propagation (VOC) with elapsed time. It was found that VOC of the thermite reaction mixture inside a steel tube has been reached around 200m/s within 100mm distance from the ignition and dramatically increased up to about twice the speed of sound in the range between 100mm and 300mm distance. Finally the VOC reached up to around 800m/s. This results imply that it is necessary to use over 300mm long cartridge of thermite reaction mixture in order to achieve normal VOC of the mixture.

• Journal of Environmental Policy
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• v.4 no.2
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• pp.83-101
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• 2005

Because of its strong potential for health hazards, the concentration levels of airborne lead (Pb) have been circumscribed by environmental laws in many countries. In this study, we made a comparative study on the environmental behavior of Pb for the acquisition of its distribution characteristics using data sets collected from major cities in Korea for a period of 6 years (1998 through 2003). According to this study, Pb concentration decreased slowly in most industrialized cities of Koreathroughout the whole study. period. In contrast, such temporal signals were not evident in data sets collected from residential, commercial, and grassland areas. Although seasonal patterns generally exhibited the occurrences of high Pb concentration during the spring, results appear to reflect the influence of Asian Dust (AD) in the springtime. The results of our study clearly indicate that Pb distribution is strongly influencedby source types in relation to their land use patterns. Comparison of our Pb data sets with that of other countries indicates that Pb concentration levels obtained from relatively cleaner districts of Korea are still significantly higher than other countries. The results of this analysis generally indicate that Pb concentrations in most areas are affected by the type and strength of man-made activities. Considering that most areas are affected by a variety of pollutants, continuous efforts are needed to control Pb concentrations in the atmosphere.

• Ocean and Polar Research
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• v.29 no.2
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• pp.87-99
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• 2007

This study was conducted to understand the source and behavior of organic matter using the fluorescent technique (excitation-emission matrix) as a part of environmental monitoring program in the Korea manganese nodule mining site in the Northeastern Pacific Ocean. Water samples were collected at $0^{\circ},\;6^{\circ}N$, and $10.5^{\circ}N$ along $131.5^{\circ}W$ in August 2005. The concentration of total organic carbon (TOC) ranged from 58.01 to $171.93\;{\mu}M-C$. The vertical distribution of TOC was characterized as higher in the surface layer and decreased with depth. At $6^{\circ}N$, depth-integrated (from surface to 200 m depth) TOC was $337.1\;gC/m^2$, which was 1.4 times higher value than other stations. The exponential decay curve fit of vertical profile of TOC indicated that 59% of organic carbon produced by primary production in the surface layer could be decomposed by bacteria in the water column. Dissolved organic matter is generally classified into two distinctive groups based on their fluorescence characteristics using three-dimensional excitation/emission (Ex/Em) fluorescence mapping technique. One is known as biomacromolecule (BM; protein-like substance; showing max. at Ex 280/Em 330), mainly originated from biological metabolism. The other is geomacromolecule (GM; humic-like substance; showing max. at Ex 330/Em 430), mainly originated from microbial degradation processes. The concentration of BM and GM was from 0.42 to 7.29 TU (tryptophan unit) and from 0.06 to 1.81 QSU (quinine sulfate unit), respectively. The vertical distribution of BM was similar to that of TOC as high in the surface and decreased with depth. However, the vertical distribution of GM showed the reverse pattern of that of BM. From these results, it appeared that BM occupied a major part of TOC and was rapidly consumed by bacteria in the surface layer. GM was mainly transformed from BM by microbial processes and was a dominant component of TOC in the deep-sea layer.