• Korean Journal of Fisheries and Aquatic Sciences
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• v.56 no.1
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• pp.28-32
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• 2023

We optimized ultrasound-assisted extraction to improve the extraction efficiency of bioactive compounds from the microalgae Acutodesmus reginae. To optimize this extraction process, we investigated the effects of solvent type, solvent concentration, extraction time, extraction number, and extraction power on the production of lutein, α-carotene, β-carotene, and chlorophylls a, and b. After sequential optimization of these main variables, the maximum amount of each compound was extracted at 30℃ with an ultrasound power of 80 W and using 99.5% methanol. Under these optimum conditions, the amount of lutein, α-carotene, β-carotene, and chlorophylls a, and b, were measured as 10.43, 8.66, 3.76, 15.43, and 6.39 mg/g dry matter respectively.

• Proceedings of the IEEK Conference
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• 1998.10a
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• pp.1263-1266
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• 1998

In this paper, we propose an optimal feature extraction method for normally distributed multiclass data. We search the whole feature space to find a set of features that give the smallest classification error for the Gaussian ML classifier. Initially, we start with an arbitrary feature vector. Assuming that the feature vector is used for classification, we compute the classification error. Then we move the feature vector slightly and compute the classification error with this vector. Finally we update the feature vector such that the classification error decreases most rapidly. This procedure is done by taking gradient. Alternatively, the initial vector can be those found by conventional feature extraction algorithms. We propose two search methods, sequential search and global search. Experiment results show that the proposed method compares favorably with the conventional feature extraction methods.

• Journal of Environmental Science International
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• v.1 no.1
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• pp.89-96
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• 1992

In this study , we have investigated leaching characteristics of heavy metals and alkalinity centering around steel mill slags by several extraction methods, for the purpose of risk assessment that exert influence on environment and offer of the foundation data of reuse by slags. Korean standard method, U.S.EPA Extraction Procedure, alkalinity extraction test and 9 step sequential fractionation experiment by Miller et al. were carried out for investigating teachability of steel mill slags. As a result of this experiment, heavy metals were little detected and it was considered that alkalinity does not exert a bad effect around environment in slabs with large particle size. By the result of 9 step fractionation experiment, heavy metal contents in slags were not plentiful, in addition, even comparatively plentiful contended heavy metals, for the most part, were likely to detained or bonded in silica matrix. Therefore, in case of slags with large particle size, it seems that teachability of heavy metals were next to impossible that is existed as a safety condition.

• Journal of Korean Dental Science
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• v.9 no.2
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• pp.55-62
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• 2016

Purpose: Alveolar bone develops with tooth eruption and is absorbed following tooth extraction. Various ridge preservation techniques have sought to prevent ridge atrophy, with no superior technique evident. Collagen has a long history as a biocompatible material. Its usefulness and safety have been amply verified. The related compound, atelocollagen, is also safe and displays reduced antigenicity since telopeptides are not present. Materials and Methods: The current study evaluated whether the $Rapiderm^{(R)}$ atelocollagen plug (Dalim Tissen, Seoul, Korea) improves tissue healing of extraction sockets and assessed the sequential pattern of bone regeneration using histology and microcomputed tomography in six beagle dogs. To assess the change of extraction socket, hard tissues were examined 2, 4, 6, and 8 weeks after tooth extraction. Result: The experimental groups showed better bone fill with slow remodeling process compared to the control groups although there was no statistical difference between groups. Conclusion: The atelocollagen seems to have a tendency to slow bone remodeling in the early phase of healing period and maintain remodeling capacity until late phase of remodeling. Also, use of atelocollagen increased the bone-to-tissue ratio compared to healing of untreated extraction socket.

• Journal of Soil and Groundwater Environment
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• v.20 no.1
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• pp.28-35
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• 2015

In this study, the mechanisms on ultrasonication enhanced metals extraction were investigated compared with the conventional washing technique. We hypothesized the mechanisms on enhanced extraction of ultrasonication: ultrasonication increased the temperature of soil slurry and decreased average particle size of soil due to breakdown of soil aggregate. Actually, the ultrasonication increased the temperature of soil slurry to $60^{\circ}C$ in this study, and the increase in the temperature enhanced the metal extraction to 15-20% even in the conventional simple mixing. The conventional washing technique decreased average size of soil particles because of breakdown of soil aggregate, and the ultrasonication decreased the size more than that of washing. The breakdown of soil aggregate improved the contact between metals and washing agent, which enhanced the extraction of metals in the ultrasonication. Therefore, we concluded that the main mechanisms of ultrasonication are increase in the temperature and breakdown of the soil aggregate. Finally, the ultrasonicaiton increased the extractability of metals upto 40% compared to conventional washing technique.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.1
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• pp.25-35
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• 2005

This study analyzed total concentrations and existing forms of heavy metals in soils of Ulsan using a sequential extraction method. Soil samples were collected from 6 categorized areas including green, residential, heavy traffic, petrochemical industrial complex(IC), mechanical and shipbuilding IC, and non-ferrous metal IC areas. which represent different emission characteristics. The highest total concentrations of heavy metals by a sequential extraction analysis were observed in the soils collected from the non-ferrous metal IC area, followed by the mechanical and shipbuilding IC and heavy traffic areas. Dominant(> 50%) existing forms of Cd, Cr and Ni were residual forms followed by Fe and Mn oxides in almost areas. Residual fractions in the non-ferrous metal IC areas were relatively lower than those in other areas. However, the fractions of organic and sulphides in the IC areas were higher. The dominant farms of Cu were much different with the investigated areas. In most areas, the dominant forms of Pb and Zn were Fe and Mn oxides, followed by residual fraction for Pb. The exchangeable and carbonate fractions represent mobility of metallic elements in soils. They are also significantly affected by the environmental renditions, such as pHs of soil and rainfall. In this study the exchangeable and carbonate fractions were lower than other fractions. Because the total concentrations of heavy metals in the soils of the non-ferrous metal IC area were extremely high, however, the mobile fractions of heavy metals in the IC area would be significant. Thus a large amount of heavy metals can be released into plants, water bodies, and soils. Therefore, urgent measures, such as source control for soil remediation of heavy metals, in the non-ferrous metal IC areas are essentially required. Analysis results obtained from the sequential extraction and the aqua regia extraction showed a high correlation, whose determination coefficients(R2) of heavy metals except Cd approximately ranged from 0.7 to 0.9.

• Proceedings of the Korean Environmental Sciences Society Conference
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• 1996.10a
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• pp.53-53
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• 1996

• Environmental Engineering Research
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• v.17 no.3
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• pp.145-150
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• 2012

Pb-contaminated soil at a clay shooting range was analyzed by the sequential extraction method to identify metal binding properties in terms of detrital and non-detrital forms of the soil. Most of the metals in the soils existed as non-detrital forms, exchangeable and carbonate-bound forms, which could be easily released from the soil by a washing method. Therefore, the characteristics of Pb desorption for remediation of the Pb-contaminated soil were evaluated using hydrochloric acid (HCl) by a washing method. Batch experiments were performed to identify the factors influencing extraction efficiency. The effects of the solid to liquid (S/L) ratio (1:2, 1:3, and 1:4), soil particle size, and extraction time on the removal capacity of Pb by HCl were evaluated. Soil samples were collected from two different areas: a slope area (SA) and a land area (LA) at the field. As results, the optimal conditions at 2.8 to 0.075 mm of particle size were 1:3 of the S/L ratio and 10 min of extraction time for SA, and 1:4 of the S/L ratio and 5 min of extraction time for LA. The characteristics of Pb desorption were adequately described by two-reaction kinetic models.

• Journal of Environmental Science International
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• v.15 no.3
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• pp.279-286
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• 2006

Electrokinetic technique was considered in removing arsenic from the abandoned mining tails. In order to estimate the removal characteristics of arsenic, the sequential extraction analysis and desorption experiment were carried out prior to the application of electrokientic process. The result of sequential extraction analysis indicated that the water soluble and exchangeable fraction, easily leachable to ground water, were very low as much as about 2.5% and the fraction except residual (38.3%), possibly extractable under very acidic or alkalic environment, was about 59%. In the result of desorption test using four different kinds of electrolytes, the mixture of citric acid and sodium dodecyl sulfate (SDS) showed the highest desorption efficiency as much as 77.3%. The removal efficiencies of arsenic from mining tailings by electrokinetic process under the different electrolyte environments were slightly low and resulted in the following order: citric acid + SDS (18.6%) > 0.1 $NHNO_3$ (8.1%) > HAc (7.4%) > Distilled water(6.6%). Also, arsenic in soil matrix was moved favorably in the direction of anodic rather than cathodic region, which is opposite trend with cationic metal ions generally existing in soil, because anionic form of arsenic is dominated in acidic soil caused by the movement of acid front form anode.

• Journal of Soil and Groundwater Environment
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• v.15 no.5
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• pp.16-22
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• 2010

Heavy metals in soils exist in various forms dependent upon surrounding conditions. As the Janghang smelter area is of concern for its high elevated heavy metal concentrations, Korean government decided to remediate the area. Main objectives of this research were; to analyze heavy metal concentrations and their existing forms in the vicinity of the smelter; and to understand differences made by analysis techniques of heavy metals. Top soils of rice field, crop field, bare field, and forestry in the area were sampled and analyzed for their physicochemical characteristics. Concentrations of Cu, Cd, Pb, and As were analyzed with two pretreatment techniques adopted using 0.1 N HCl and aqua regia. To analyze existing forms of heavy metals, Tessier's schemes for sequential extraction technique were adopted. Exchangeable fraction and carbonate bound fraction of heavy metals may pose potential threat to environment and were in the order of Pb > As > Cu > Cd. If assessing mobile fraction of heavy metals by land uses, the order was forestry > bare land > crop field > rice field. When analyzed using Tessier's scheme, high ratio of residual fractions to total arsenic concentration should be considered for remediation design of the area.