• Journal of Periodontal and Implant Science
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• v.28 no.4
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• pp.809-822
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• 1998

Adequate root preparation in the treatment of periodontal disease often involves mechanical instrumentation to remove plaque, calculus perhaps contaminated cementum. Although meticulous scaling and root planing may remove some cementum, the use of aggressive root planing to remove cementum does not appear warranted. So ultrasonic device and rotary instrument appear to be replacing hand instrument. But it is not clear those instruments make smooth root surface as hand instrument. The roghness of the root surface were evaluate with SEM following instrumentation with Gracey curette, Perio Clean and piezo ultrasonic device(Setlec) with various tip. 20 extracted teeth were used in vitro experiment, and 9 teeth of a patient destined for extraction for periodontal reasons were utilized in vivo experiment. It was demonstrated that hand curette created the smoothest surface, while diamond tip tended to roughen the root surface. But the hand curette, Perio Clean, and piezo ultasonic device with scaler tip tend to remove cementum completely. Piezo ultrasonic device with curette-like tip made the desirable smooth surface with partial removal of cementum.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.34S no.6
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• pp.58-66
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• 1997

This paper proposes a multiresolution surface parameter estimation method for range images. Based on robust estimation of surface parameters, it approximates a patch to a planar surface in the locally adaptive window. Selection of resolution is made pixelwise by comparing a locally computed homogeneity measure with th eglobal threshold determined by te distribution of the approximation error. The proposed multiresolution surface parameter estimation method is applied to range image reconstruction. Computer simulation results with noisy rnag eimages contaminated by additive gaussian noise and impulse noise show that the proposed multiresolution reconstruction method well preserves step and roof edges compared with the conventional methods. Also the segmentation method based on the estimated surface parameters is shown to be robust to noise.

• Proceedings of the KIEE Conference
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• 2004.11a
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• pp.248-250
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• 2004

We have investigated the surface state of 154kV polymeric insulators exposed to in-service conditions for about five years. In order to evaluate surface aging of silicone rubber exposed to real field environments, we used various analytic methods such as contact angle, ATR-FTIR, SEM-EDS. Although contaminants were accumulated on weathershed surface, polymeric insulator has retained its intrinsic surface hydrophocity. In addition, ATR-FTIR confirmed the diffusion layer of a low molecular weight silicone fluid on surface layer and no surface cracking and chalking were Indicated by SEM. Polymeric insulators have still retained their improved pollution performance over porcelain insulators. That will lead to very low frequency of flashovers throughout their useful life, often under contaminated conditions.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.46 no.5
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• pp.626-637
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• 2013

We measured the grain size, ignition loss (IL), chemical oxygen demand (COD), acid volatile sulfide (AVS) and trace metals (Al, Fe, Cu, Pb, Zn, Cd, Cr, Mn, Hg, and As) of intertidal surface sediment collected from 11 islands (62 stations) in the southern region of Jeollanam Province. The objective of this research was to evaluate the organic matter and trace metals contaminations of sediments from coastal island tidal flats. Surface sediment texture was characterized as follows: mud, sandy silt, muddy sand, and slightly gravelly sand facies. The finer sediments are mainly dominated in the northern part of each island. The concentrations of IL, COD, AVS and some trace metals (Al, Fe, Zn, Cr, Cu, and Hg) were higher in the northwestern part of Wan Island and the area between Gogeum and Sinji Islands, and were associated with relatively finer sediment, as compared to other locations. The concentrations of Mn, Pb, Cd, and As were higher in the northwestern and southeastern parts of Geoguem and Pyungil Islands, but were not correlated with mean grain size. Based on sediment quality guidelines (SQGs), the concentrations of trace metals were lower than the values of effect range low (ERL), used in United States, and threshold effects level (TEL), used in Korea, with exception of As. Similarly, the intertidal sediments were moderately contaminated with As, based on the the enrichment factor (EF) and the geoaccumulation index ($I_{geo}$). The high concentration of As in intertidal sediments from this study region may be due to the input of naturally or artificially contaminated submarine groundwater, contaminated waste from seaweed aquaculture operations and/or land-based seaweed processing facilities. Further studies are needed to identify the sources of As in this study region, and to determine the effects of As contamination on coastal ecosystem.

• Journal of Soil and Groundwater Environment
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• v.25 no.2_spc
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• pp.28-54
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• 2020

Even though a systematic sampling approach is very crucial in both the general and detailed investigation phases to produce the best conceptual site model for contaminated sites, the concept is not yet established in South Korea. The U.S. Environmental Protection Agency (EPA) issued the 'Strategic Sampling Approaches Technical guide' in 2018 to help environmental professionals choose which sampling approaches may be needed and most effective for given site conditions. The EPA guide broadly defines strategic sampling as the application of focused data collection across targeted areas of the conceptual site model (CSM) to provide the appropriate amount and type of information needed for decision-making. These strategic sampling approaches can prevent the essential data from missing, minimize the uncertainty of projects and secure the data which are necessary for the important site-decisions. Furthermore, these provide collaborative data sets through the life cycle phases of projects, which can generate more positive proofs on the site-decisions. The strategic sampling approaches can be divided by site conditions. This technical guide categorized it into eight conditions; High-resolution site characterization in unconsolidated environments, High-resolution site characterization in fractured sedimentary rock environments, Incremental sampling, Contaminant source definition, Passive groundwater sampling, Passive sampling for surface water and sediment, Groundwater to surface water interaction, and Vapor intrusion. This commentary paper introduces specific sampling methods based on site conditions when the strategic sampling approaches are applied.

• Journal of Energy Engineering
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• v.23 no.3
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• pp.17-20
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• 2014

A magnetic fluid separation technology was confirmed to be very effective to remove the suspended solids from contaminated water. We have surveyed on the effects of operating variables on the characteristics of suspended solids(SS) removal investigated through the test runs using magnetic powder. Magnetic flocculation here formed by adsorbing fine magnetites on the surface of suspended solid was observed. The strength of magnet was of significance in determining the SS removal efficiency.

• Journal of Soil and Groundwater Environment
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• v.15 no.5
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• pp.1-7
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• 2010

Electrokinetic technology was applied to remediate Cu, Pb and As-contaminated paddy soil. Removal of metal is highly dependent on the processing fluid during electrokinetic treatment. Tap water, NaOH, $HNO_3$, $Na_2EDTA$, and citric acid were evaluated as the processing fluids to enhance metal removal. Cu and Pb were transported toward cathode, however, it did not removed from soil section, while 56.6% of As was removed at a acidic condition. The strong acidic condition with nitric acid as a processing fluid enhanced the desoprtion of As from soil surface. However, longer operation time is needed to get the higher removal of Cu and Pb, and the acidification of soil after electrokinetic treatment should be solved.

• Environmental Engineering Research
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• v.23 no.2
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• pp.175-180
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• 2018

Box-Behnken Design (BBD) under response surface methodology (RSM) was implemented to optimization the operating parameters and assess the removal and recovery efficiencies of crude oil from contaminated soil using subcritical water extraction. The effects of temperature, extraction time and water flow rate were explored, and the results indicate that temperature has a great impact on crude oil removal and recovery. The correlation coefficients for oil removal ($R^2=0.74$) and recovery ($R^2=0.98$) suggest that the proposed quadratic model is useful. When setting the target removal and recovery (>99%), BBD-RSM determined the optimum condition to be a temperature of $250^{\circ}C$, extraction time of 120 min, and water flow rate of 1 mL/min. An experiment was carried out to confirm the results, with removal and recovery efficiencies of 99.69% and 87.33%, respectively. This result indicates that BBD is a suitable method to optimize the process variables for crude oil removal and recovery from contaminated soil.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2001.04a
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• pp.261-266
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• 2001

Three innovative technologies to remediate trichloroethylene (TCE) in situ were (or currently are being) evaluated at a TCE-contaminated groundwater site at Edwards Air Force Base (AFB), California. The three technologies all make use of groundwater recirculation to obviate the need to pump contaminated groundwater to the surface fer treatment. The first technology, which implements aerobic cometabolic bioremediation to destroy TCE in situ, successfully reduced dissolved TCE concentrations from above 1 mg/L to 20-30 $\mu\textrm{g}$/L. The second technology, in-well vapor stripping (IWVS), is capable of treating dissolved TCE at concentrations in the tens to hundreds of mg/L. Finally, the third technology, bioenhanced in-well vapor stripping (BEHIVS): is a combination of the first two technologies, and is designed to reduce very high levels of TCE (tens to hundreds of mg/L) to concentrations that meet regulatory requirements 5 $\mu\textrm{g}$/L). Results of field evaluations of tile first two technologies are presented, and the design of the BEHIVS system. as well as model predictions of BEHIVS performance and the current status of the technology field evaluation. is discussed.

• Progress in Superconductivity and Cryogenics
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• v.22 no.2
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• pp.1-6
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• 2020

Large-scale civil engineering works discharge a large amount of soil suspension contaminated with natural heavy metals. Most of the heavy metal ions due to industrial activities and minings are accumulated in the soils and the sediments of lakes and inner bays through the rivers. It is necessary to remove heavy metals from the soils and the sediments, because some of these heavy metals, such as arsenic and cadmium, have significant biological effects even in small amounts. This study proposes a new volume reduction method of the contaminated soils and sediments by superconducting magnetic separation. Our process can remove the specific minute minerals selectively, which adsorbs heavy metals depending on pH. As a fundamental study, the adsorption behaviors of arsenic and cadmium on minute minerals as a function of pH were investigated, and the adsorption mechanism was discussed based on the crystal structure and pH dependence of surface potential in each minute minerals.