• 한국해양학회지
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• v.28 no.3
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• pp.241-258
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• 1993

To investigate the sedimentary environments on the coastal areas of Imja to Nakweol islands which show very complex shorelines and several zonal sand ridges in NE-SW direction, southwestern coast of Korea, a total of forty samples were taken by a grab sampler and sedimentological and micropaleontological studies on those samples were carried out. The present study area are classified into muddy sandy gravel, sand, city sand, sandy silt and silt facies. With statistical moment parameters such as mean, sorting, skewness and ketosis for the sediments in the study area, the sediments are generally categorized as shallow sedimentary facies. The characters that are observed in quartz grains among the sandy sediments of the study area imply the existence of high energy environments, temporal exposures in atmosphere and the mixing of clastic sediments of the several different origins. In the sediments of the study area, one genera belonging to six silicoflagellata species and five genera belonging to five nannoplankton species were detected. On the basis of the micro-organism assemblage, the study area seems to be influenced by active reworking dominantly under warm water masses. In addition, organic matter ad carbonate contents in the sediments did not show a definite relation with the occurrences of the micro-organisms in the study area.

• Korean Journal of Heritage: History & Science
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• v.46 no.1
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• pp.290-317
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• 2013

The objectives of this study are to investigate the natural heritage and scientific value of various geosites on Udo Island, and to evaluate the sites as natural monuments and as world natural heritage properties. Udo Island includes a variety of geoheritage sites. Various land forms formed during the formation of the Someori Oreum formed by phreatomagmatic eruptions. The essential elements for the formation of Udo Island are the tuff cone, overflowing lava and overlying redeposited tuff sediments. Various coastal land forms are also present. About 6,000 years B.C., when sea-level rose close to its present level due to deglaciation since the Last Glacial Maximum, carbonate sediments have been formed and deposited in shallow marine environment surrounding Udo Island. In particular, the very shallow broad shelf between Udo Island and Jeju Island, less than 20 m in water depth, has provided perfect conditions for the formation of rhodoids. Significant amounts of rhodoids are now forming in this area. Occasional transport of these rhodoids by typhoons has produced unique beach deposits which are entirely composed of rhodoids. Additional features are the Hagosudong Beach with its white carbonate sands, the Geommeole Beach with its black tuffaceous sands and Tolkani Beach with its basalt cobbles and boulders. Near Hagosudong Beach, wind-blown sands in the past produced carbonate sand dunes. On the northern part of the island, special carbonate sediments are present, due to their formation by composite processes such as beach-forming process and transportation by typhoons. The development of several sea caves is another feature of Udo Island, formed by waves and typhoon erosion within tuffaceous sedimentary rocks. In particular, one sea cave found at a depth of 10 m is very special because it indicates past sea-level fluctuations. Shell mounds in Udo Island may well represent the mixed heritage feature on this island. The most valuable geoheritage sites investigated around Udo Isalnd are rhodoid depostis on beaches and in shallow seas, and Someori Oreum composed of volcanoclastic deposits and basalt lava. Beach and shallow marine sediments, composed only of rhodoids, appear to be very rare in the world. Also, the natural heritage value of the Someori Oreum is outstanding, together with other phreatomagmatic tuff cones such as Suwolbong, Songaksan and Yongmeori. Consequently, the rhodoid deposits and the Someori Oreum are worth being nominated for UNESCO World Natural Heritage status. The designation of Someori Oreum as a Natural Monument should be a prerequisite for this procedure.

• Journal of the Korean Recycled Construction Resources Institute
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• v.11 no.4
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• pp.332-340
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• 2023

This study investigated the effects of nanoparticles on the fracture toughness of cement mortar. Three-point bending tests, compressive tests, and slump tests were conducted on cement mortars reinforced with carbon nanotubes(CNTs), nanosilica(NS), and nano calcium carbonate(NC), respectively. Cement mortar with a water-to-cement ratio and a sand-to-cement ratio of 0.45 and 1.5, respectively, and reinforced with 0 and 2 vol.% of 19.5 mm steel fibers, respectively, was used. Reinforcement with nanoparticles partially improved the fracture toughness and compressive strength of the cement mortar. However, in the case of cement mortar reinforced with steel fibers, the reinforcement with nanoparticles was found to reduce the flowability of the mortar, adversely affecting the dispersion of steel fibers, and ultimately leading to a decrease in fracture toughness, contrary to the intended enhancement. Additional research is needed to improve the decrease in mortar fluidity caused by the reinforcement with nanoparticles.

• Journal of the Korean earth science society
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• v.24 no.5
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• pp.477-490
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• 2003

Bottom sediments from Youngil Bay, East Coast of Korea, were analyzed for grain composition as well as elemental compositions and total organic carbon (TOC) content in order to investigate the spatial variability and content of metal elements. Grain size distribution of the sediments seems to be controlled by anticlockwise current pattern with bottom topography of the study area. Spatial variability of TOC and all elemental contents reflects those of grain size, but an exception was found in the harbor area (Old-Port): their contents are high in the central part of the bay with the muddy sediment and decrease toward the sand-dominated coastal zone. However, contents of Ca, Sr, K are high in the sand-dominated coastal zone and contents of some heavy metals (Cd, Cu, Zn) are high in the Old-Port area and the mouth of Hyeongsan River. The correlation matrix and R-mode factor analyses reveal that four important factors controlling the distribution of metals in the bay are sediment grain size (or quartz dilution effect), the formation of sulfide minerals associated with decomposition of organic matters under anoxic geochemical environment, calcium carbonate (mainly shell fragments) and coarse-grained feldspar mineral. According to the metal content of labile fraction an CER (concentration enrichment ratio) value, high accumulation of some heavy metals in the harbor area seems to result not formed by early diagenetic processes under anoxic environment.

• Applied Chemistry for Engineering
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• v.31 no.5
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• pp.481-486
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• 2020

To evaluate geochemical characteristics of surface sediments in Samcheok Port, the distribution characteristics of particle sizes, organic matters and heavy metals were investigated. The sediments showed a mixed property of sand, silt, and clay, however fine-grains dominated at the inner port and coarse-grains dominated at the outer port. The organic (COD, TOC, and IL) contamination of the sediment at the inner port were higher than that of the outer port, and the concentrations of total nitrogen and total phosphorus at the inner port was higher than those of the outer port. Also, heavy metals contamination of surface sediments at the inner port was higher than those of the outer port (except for As). From the results of high organic matter concentrations and C/N ratio at the inner port, it is considered that the contamination of organic matters was mainly derived from the land. The correlation analysis among the particle size, chemical composition, and heavy metals resulted in high correlation between silt-clay and heavy metals, and between organic matters and heavy metals. The sequential extraction results of heavy metals showed the sum of exchangeable, carbonate, and oxide fractions of Ni, Zn, Cu, Pb, Cd, and As were 14.8, 49.8, 39.1, 32.2, 51.8 and 26.6%, respectively.

• Asian Journal of Turfgrass Science
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• v.20 no.2
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• pp.223-235
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• 2006

Soil testing laboratories unfamiliar with turfgrasses will often overestimate the plant's need for phosphorus and underestimate the need for potassium. This is partly due to differences in rooting between grasses and many garden plants and crops. The grasses are generally more efficient in extracting phosphorus from the soil, reducing their need for phosphorus fertilizer. The fact that crop yield is often the primary objective in field crop production, and is usually of little interest in turfgrass management, may affect soil test interpretation for potassium. Potassium levels above those required for maximum tissue yield of grasses may improve stress tolerance and turfgrasses will usually benefit from higher applications of this element. There are also diffrrences in soil testing philosophies. Some laboratories use the sufficiency level of available nutrients(SLAN) approach, whereas others prefer the basic cation saturation ratio(BCSR) approach. Some will use a combination of the two methods. The use of the BCSR theory easily lends itself to abuse and questionable fertilizer applications and products are sometimes recommended citing imbalances in cation ratios. The usefulness of the BCSR ratio theory of soil testing varies with soil texture and interpretations on tests performed on sand-based media are particularly a problem. Other soil testing problems occur when sand-based media used on sports fields and golf greens contain free calcium carbonate. The ammonium acetate extractant at pH 7.0 dissolves excessive amounts of calcium that can bias cation exchange capacity measurements and measurements of cation ratios. Adjusting the pH of the extractant to 8.1 can improve the accuracy of the testing procedure for calcareous media.

• Journal of Soil and Groundwater Environment
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• v.18 no.7
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• pp.73-80
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• 2013

Fine suspended solids from coal mine drainage were treated in the treating plant, using two different pilot-scale inclined clarifiers: radial and lamella types. Suspended solids in the mine drainage were monitored along with other geochemical factors, and metal contents. Fe and Mn are the main chemical components in the drainage, which exist predominantly as total metal forms, whereas dissolved portion is negligible. The raw mine drainage is subject to physical and chemical treatment using $CaCO_3$ and NaOH, therefore the suspended solids are thought to be composed of Fe and Mn precipitates, possibly $Fe(OH)_3$, along with carbonate precipitates. The elemental composition of precipitates are confirmed by SEM-EDS analysis. As nearly all the dissolved ions were precipitated in the primary process by $CaCO_3$, no further aeration or prolonged oxygenation are of necessity in this plant. Adoption of inclined clarifier proved to be effective in treating fine suspended solids in the current plant. Successful application of the inclined clarifier will also be beneficial to improve the current treating process by excluding the current application of chemical agent in the first stage. The final effluents from the pilot plant meet the national standards and the low dissolved Fe and Mn contents are expected not to cause secondary precipitation after discharge.

• Journal of Korean Society of Water and Wastewater
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• v.22 no.3
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• pp.379-387
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• 2008

The pH & alkalinity adjustment method by lime and carbon dioxide($CO_2$) for corrosion control in water distribution system was investigated to evaluate the corrosion characteristics of metal pipes, such as galvanized iron, copper, stainless steel, and carbon steel. When the pH in sand filtered and ozone+GAC treated water was increased with lime and $CO_2$ from 7.5 to 8.0, the concentration of residual chlorine decreased at higher pH and longer reaction time; the concentration of trihalomethane increased. The corrosion rate of coupons with corrosion control using lime and carbon dioxide was showed much smaller than those without corrosion control using pilot-scale simulated distribution system. The galvanized iron was corroded much faster than carbon steel, copper, and stainless steel. Especially, copper and stainless steel coupons were hardly corroded. The galvanized iron and carbon steel coupons with corrosion control were produced the corrosion products less than those without corrosion control by the results of environmental scanning electron microscope(ESEM) and energy dispersive x-ray spectroscopy(EDS) analyses. The galvanized iron coupon with pH and alkalinity adjustment by lime and carbon dioxide was detected about 30 percent of zinc, when the carbon steel was detected about 30 percent of calcium by calcium carbonate products formation. For the results of X-ray diffraction(XRD) analyses, the goethite(${\alpha}$-FeOOH) was identified as primary corrosion product of galvanized iron without corrosion control, while the Zinc oxide(ZnO) was found on corrosion products of galvanized iron coupon with corrosion control as the results of EDS analyses. However, the carbon steel corrosion products regardless of corrosion control were composed predominantly of maghemite(${\gamma}-Fe_2O_3$) and hematite(${\alpha}-Fe_2O_3$).

• Journal of the Speleological Society of Korea
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• no.67
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• pp.1-9
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• 2005

The lava-calcification which was found in Geunjisul located in Jeju-do (Korea) was investigated to analyse the cause of calcification through the internal factor of cave structure and surroundings in company with relevant ecological system. The volcanic cave is degenerated after formation from volcano lava extravasation, however, the cave became more stronger with solidification and petrification by the reinforced structure of calcification as the cement in concrete buildings unprecedentedly if the lava-calcification occurred in the cave. Such a Progressive Phenomena of lava-calcification was verified in progress first in Geonjigul located at Hyubjae-ri, but those would be found in other simiiar case of caves distributed and connected with seaside of shelly sand beach.

• Korean Journal of Soil Science and Fertilizer
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• v.25 no.1
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• pp.1-7
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• 1992

Sand and silt size fractions of soils which were derived from five major rocks of granite, granite-geniss, limestone, shale, and basalt in Korea were studied. Determination of the mineralogical and chemical composition of rock-forming mineral breakdown which is accompanied by the formation of secondary minerals. The chemical composition of the fraction was largely changed with the content of weatherable and resistant soil minerals such as ferromagenesian minerals, carbonates, and guartz. In the sand fractions of the soils from the granite and granite-gneiss, chlorite-vermiculite mixed layers seem to be an intermediate weathering product prior to the weathering state of the formation of vermiculite from chlorite. Kaolin minerals in the silt fractions of the soils from the granite-gneiss are considered to be formed by the pseudomorphic transformation of plagioclase. In the sand and silt fractions of the soils derived from the limestone, large amount of calcite and dolomite seems to have been inherited from the parent rocks. The primary chloritc, micas, and feldspars are considered to be formed from the weathering remains after leaching of carbonate minerals during the soil formation. In the residual soils(Gueom series) developed from the basalt, quartz and micas were coexisted with plagioclase and augite inherited from the parent rock.