• Environmental Sciences Bulletin of The Korean Environmental Sciences Society
• /
• v.4 no.3
• /
• pp.185-193
• /
• 2000

A water treatment agent with antimicrobial activity(Ag-Os) was created by exchanging silver ion($Ag^{+}$) on calcined oyster shell powder. The desorption of the exchanged silver ion was negligible, thereby indicating a stable antimicrobial water treatment agent. The sterilization effect of Ag-Os on underwater microorganisms was then investigated. An MIC (Minimum Inhibitory Concentration) test result indicated that Ag-Os had an excellent sterilization effect on G-germs, such as Escherichia coli and Pseudomonas aeruginosa. Most germs were annihilated with an Ag-Os concentration of 200 ppm and contact time of 60 minutes. The sterilization effect was mainly dependent on the contact time. The zeta potential of the Ag-Os powder adsorbed on sand was measured relative to the concentration of exchanged silver ion. As the concentration of the exchanged silver ion increased, the surface charge density of the anions on the surface of the Ag-Os powder adsorbed on sand also increased. Accordingly, this result indicated that a higher silver ion than ion exchange capacity was present on the particle surface due to adsorption. Consequently, this increased concentration of exchanged silver ion would appear to significantly enhance the sterilization power.

• Applied Microscopy
• /
• v.50
• /
• pp.18.1-18.7
• /
• 2020

The olfactory anatomy and histology of Lethenteron reissneri were researched using a stereo microscope, a light microscope, and a scanning electron microscope. As in other lampreys, it shows same characters as follows: i) a single olfactory organ, ii) a single tubular nostril, iii) a single olfactory chamber with gourd-like form, iv) a nasal valve, v) a nasopharyngeal pouch, vi) a sensory epithelium (SE) of continuous distribution, vii) a supporting cells with numerous long cilia, viii) an accessory olfactory organ. However, the description of a pseudostratified columnar layer in the SE and Non SE is a first record, not reported in sea lamprey Petromyzon marinus. In particular, both 19 to 20 lamellae in number and olfactory receptor neuron's quarter ciliary length of the knob diameter differ from those of P. marinus. From these results, it might be considered that the olfactory organ of L. reissneri shows well adaptive structure of a primitive fish to slow flowing water with gravel, pebbles, and sand and a hiding habit into sand bottom at daytime. The lamellar number and neuron's ciliary length may be a meaningful taxonomic character for the class Petromyzonida.

• Journal of Environmental Impact Assessment
• /
• v.7 no.1
• /
• pp.71-80
• /
• 1998

The purpose of this study is to investigate and analyze a conservation state and a sustainable use of coastal wetland in Sindu-ri Tae-an, using the plant community structure analysis and the awareness result of local residents by published paper. To investigate a forest structure in Sindu-ri area, twenty plots were set up and surveyed. The community, is divided by three groups. The divided groups are Robinia pseudoacacia(I), Pinus thunbergii-Robinia pseudoacacia(II), Robinia pseudoacacia(III). Survey site I is simple canopy layer and deteriorative forest. Survey site II is grassland and swamp, where Pinus thunbergii-Robinia pseudoacacia is dominant trees of vegetation. Robinia pseudoacacia is competition species with Pinus thunbergii in survey site II. Survey site III is barren land(sand-hill) where main species is Robinia pseudoacacia. As a result, survey II district is considered as the most suitable for the conservation of species diversity. It is proposed in this paper that the ecological nature trail would be connected in survey site I and II for environmental education. The local residents of Tae-an, where natural environment is well-conserved, prefer conservation to development of the region. In case of Tae-an, where the condition of the natural environment is well conserved and the development potential exists, the development is in harmony with the environmental education program.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
• /
• v.7 no.2
• /
• pp.79-86
• /
• 2009

Concrete materials in nuclear facilities may become contaminated or activated by various radionuclides through different mechanism. Decommissioning and dismantling of these facilities produce considerable quantities such as concrete structure, rubble. In this paper, the characteristics distribution of the radionuclide have been investigated for the effects of the heating and grinding test for aggregate size such as gravel, sand and paste from decommissioning of the TRIGA MARK II research reactor and uranium conversion plant. The experimental results showed that most of the radionuclide could be removed from the gravel, sand aggregate and concentrated into a paste. Especially, we found that the heating temperature played an important role in separating the radionuclide from the concrete waste. Contamination of concrete is mainly concentrated in the porous paste and not in the dense aggregate such as the gravel and sand. The volume reduction rate could be achieved about 80% of activated concrete waste and about 75% of dismantled concrete waste generated from UCP.

• Journal of the Korean Society of Environmental Restoration Technology
• /
• v.3 no.3
• /
• pp.81-99
• /
• 2000

The shelterbelts are very important to conserve and protect the sandy land, vegetation coverage, farmland, livestock and human life in the desertified land. The shelterbelts are constructed by the several row-plantings of high-adaptable species in the desertified land. The shelterbelts have various kind of type, and there are shelterbelts for conservation of farmland in dry the region, the protective shelterbelts (windbreaks for blowing-sand, artificial sanddune fixation by revegetation, and construction of farmland shelterbelts to protect farmland and pasture from wind erosion, etc.) in the semi-dry steppe, shelterbelts around the villages and oasis for sanddune fixation, shelterbelts for protection of railroads, and so on. The shelterbelts consist of main she1terbelts and minor shelterbelts. The main shelterbelts were constructed by being perpendicular to main wind direction, and the minor shelterbelts were constructed by being perpendicular to the main shelterbelts. Generally, the width of shelterbelts is 8~20m, and the number of row-planting is 4~10. The grid sizes of shelterbelts networks are $400{\times}400m$, $300{\times}500m$, $100{\times}200m$, and so on, and there are ventilation type and closing type in the type of shelterbelt. The width, number of row-planting, grid size and type of shelterbelt are selected by the local characteristics. The effects of shelterbelts are mainly the climate improvement and mitigation, such as prevention of occurrence of strong wind, cold wind and blowing-sand. And, the other effects of shelterbelts are effect of reforestation, increase of agricultural productions, establishment of greenbelts and green forests, construction of landscape-eco shelterbelts, improvement of life environment of local villages, supply of fuel wood and agricultural wood, land amelioration, effect of revegetation and restoration of desertified land, and so on. The kinds of the tree species mainly used for the construction of shelterbelts have differences between regions, but main species are Populus euphratica, Populus simonii, Populus bolleana, Populus tomentosa, Salix flavida, Salix mongolica, Tamarix chinensis, Hedysarum scoparium, and so on.

• Journal of the Korean Geophysical Society
• /
• v.5 no.4
• /
• pp.271-281
• /
• 2002

Interpretation of high-resolution seismic profiles collected from the inner shetf of the Korea Strait reveals that the shelf sequence in this area consists of three sedimentary units (I, II, and III in a descending order) formed after the last glacial maximum. Lower two units (II and III) represent the transgressive systems tract formed during the Holocene transgression, Unit III above the sequence boundary is interpreted to be the transgressive estuarine deposit, whereas Unit ll above the ravinement surface forms a thin transgressive sand which consists of the sediment produced through shoreface erosion and winnowing during the transgression. Unit I above the maximum flooding surface is the highstand systems tract consisting mainly of recent muds derived from the Nakdong River.

• Journal of the korean academy of Pediatric Dentistry
• /
• v.24 no.1
• /
• pp.82-94
• /
• 1997

For the purpose of establishing the most appropriate method of bonding between glass ionomer liners and composite resin and comparing the materials for sandwich technique, an experiment was performed to measure the shear bond strengths between the two with the variables in the surface treatment of liners and elapsed time till composite buildup. Materials used were Vitrebond and Fuji II LC, each as the restorative and liner respectively, and each group was subdivided by surface treatment (acid etching and sandblasting) and time elapsed from GIC filling to composite buildup (immediately, 1 day, 7 days), consisting 12 groups as a whole. Each subgroup was composed of 10 specimens and the shear bond strength between GIC liners and composite resin was measured under UTM and analyzed. The result were as follows: 1. The shear bond strength between two materials was highest when initially filled Fuji II LC was sandblasted after 1 days and composite built-up (Group FS1). And the lowest value was found when GIC was acid-etched after 7 days and composite built-up (Group FE7). Significant difference was found between the two groups. (P<0.01) 2. In regard of surface treatment of GI liners, acid-etched group (VE) showed higher bond strength than sandblasted group (VS) for Vitrebond. But, the reverse was true for Fuji II LC. (P<0.05) 3. In regard to the time elapsed from GI filling to composite buildup, the group of 1 day elapse showed relatively higher strength for Vitrebond. On the contrary, immediate buildup group (FE0) was stronger for acid-etched group and 1 day elapse group(FS1) was higher for sand-blasted group in Fuji II LC. (P<0.05)

• Journal of The Geomorphological Association of Korea
• /
• v.17 no.2
• /
• pp.41-52
• /
• 2010

The paleovegetation environments relevant to the geomorphic properties were constructed by pollen analysis in the coastal dune (S1) and marginal trench (S4) of Ssangho at the Osan-ri site. The organic sand layer in the coastal dune (S1) accumulated on the remains of the Neolithic Age correlates to approximately 4,000 yr BP and the pollen zone can be divided with a boundary of approximately 2,000 yr BP. Pinus thunbergii definitely dominated and a small quantity of Quercus. Pollenzone I can be characterized by the dominance of AP and Compositae. The pollenzone II as the dominant period of NAP like Gramineae, Artemisia and Fagopyrum shows the properties of agricultural period. During the times of accumulation of upper organic layer in alluvial plain (S4), broad-leaved trees such as Alnus were dominant and Compositae, Gramineae, Artemisia, Typha, Umbelliferae and Persicaria show the high occurrence rates. The pollen composition of S4 indicates the agricultural activities with the dominance of NAP and correlates to the pollenzone II of the coastal dune (S1).

• Journal of Korean Society of Environmental Engineers
• /
• v.33 no.2
• /
• pp.85-92
• /
• 2011

Evaluation of the removal efficiencies of Fe(II) by reactive sand media coated with manganese (MCS), iron (ICS) and both of iron and manganese (IMCS) was investigated as functions of solution pH ranging from 2 to 9, reaction time and concentration of Fe(II) in a batch reactor using each reactive medium and additional oxidants such as $KMnO_4$ and NaOCl. When only Fe(II) was present in solution without any reactive medium, removal of Fe(II) was quite low below pH 5 due to a slow oxidation of Fe(II) and/or negligible precipitation but greatly increased above pH 5 due to a rapid oxidation of Fe(II) and subsequent precipitation of oxidized Fe species. ICS showed negligible efficiency on the removal of Fe(II) through adsorption. However, an efficient removal of Fe(II) was observed at low solution pH in the presence of IMCS or MCS through rapid oxidation and subsequent precipitation. Removal efficiency of Fe(II) by IMCS in the presence or absence of NaOCl was quite similar. Removal rate of Fe(II) by IMCS and additional oxidants gradually increased as the solution pH increased. From the kinetic experiments, removal pattern of Fe(II) was better described by pseudo-second-order equation than pseudo-first-order equation. A rapid removal of Fe(II) using IMCS in the presence of $KMnO_4$ was observed in the first 10 min. The initial removal rate of Fe(II) using $KMnO_4$ was 14,286 mg/kg hr. In case of using NaOCl, the removal of Fe(II) occurred rapidly in the first 6 hrs and then reached the near-equilibrium state. Removal of Fe(II) on IMCS was well expressed by Langmuir isotherm and the maximum removal capacity of Fe(II) was calculated as 1,088 mg/kg.

• Korean Journal of Environment and Ecology
• /
• v.38 no.1
• /
• pp.1-21
• /
• 2024

This study conducted surveys to identify the distribution of communities and flora according to vegetation in the coastal sand dunes of Sagye in Jeju Special Self-Governing Province, located at the southernmost tip of Korea. The survey was conducted over 20 sessions from April 2020 to October 2021. As a result of the study, physiognomy was classified into six correlated vegetation types: plant communities on the salt marsh, annual communities on a coastal drift-line, herb communities on a dune, shrub communities on a coastal dune, forest-edge communities on a dune, and artificial afforestation vegetation. The survey identified 43 communities, and a total of 212 taxa were found to be distributed among 62 families, 166 genera, 191 species, 15 varieties, 3 subspecies, and 3 forma. It was found that there were five rare plant taxa distributed in the area, including the Cymbidium macrorrhizum which was classified as an endangered Class II plant by the Ministry of Environment. Floristic target species identified by the surveys included 2 taxa for grade V, 5 taxa for grade IV, 15 taxa for grade III, 14 taxa for grade II, and 19 taxa for grade I. Climate-sensitive biological indicator species included 11 indicator and 2 candidate species, representing a high ratio of 33.3% of all indicator species and 15.4% of candidate species. Naturalized plants included 16 families, 43 genera, and 52 taxa, with a naturalization rate of 21.1% and an urbanization index of 24.5%. It is expected that these results will be widely used as data needed to prepare conservation and management measures for biodiversity in response to climate change in coastal dunes in the future.