• Journal of the Mineralogical Society of Korea
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• v.20 no.2 s.52
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• pp.71-81
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• 2007

The marble-type dolomite from the Jasung Mine, which was farmed by duplicated affects of contact metamorphism and subsequent hydrothermal alteration, corresponds to a high-purity dolomite ranging up to above 98wt.% in dolomite contents. The dolomite contain minor impurities such as quartz, muscovite, and pyrite. It is characteristic that the dolomite is fairy Fe-rich corresponding to 0.4 wt.% due to the presence of pyrite of possible hydrothermal origin. The dolomite is nearly white-colored and constituting with subhedral crystals ranging $0.35{\sim}0.46mm$M in size, forming equigranular texture. Compared to the typical high-Ca limestone from the Pungchon Formation, the powder characteristics of dolomite is rather superior in milling efficiency, yields of fine particles, and size distribution. In addition, except for iron contents, the dolomite powder is no less superior than the limestone in quality and characteristics as fillers with respects to not only whiteness, oil absorption, and specific surface area but also shape characters such as elongation ratio, aspect ratio, and sphericity. This good characteristics of dolomite powder seem to be originated basically from comparatively higher grade and crystallinity of dolomite. Higher iron contents and the presence of sulfides prevents the dolomite from application for uses by thermal treatment, except for metallic manufacture. However, if proper ore separation procedure is available, the dolomite can be sufficiently utilized as substitutes for high-Ca limestone in most fields of filler industries.

• Tunnel and Underground Space
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• v.31 no.6
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• pp.623-646
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• 2021

As the demand for electric power increases with acceleration of electrification at home and abroad, the needs for coal-fired electrical power plant are accordingly increased. However, these coal-fired electrical power plants induce also many environmental problems such as increase of air pollutants, increase of possibility of land contamination by reclamation of coal ash, even though these power plants have a good economical efficiency. In case of a by-product of coal-fired electrical power plants, only 70% of them are recycled and the remaining 30% of by-product are fully buried in surrounding ground. Consequently, this study deals with coal ash backfilling mechanism in abandoned mine openings for the purposes of increasing the coal ash recycling rate as well as securing the mine area stability. In order to analyze the backfill and ground reinforcement by interaction between rock mass and backfills, the copying samples of discontinuous surface with different roughnesses were produced for bond strength tests and direct shear tests. And statistical analysis was also conducted to decide the characteristics of bond and shear behavior with joint roughness and their curing day. Numerical simulations were also analyzed for examining the effect of interface behavior on ground stability.

• The Journal of Engineering Geology
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• v.33 no.3
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• pp.427-438
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• 2023

We carried out a geological survey to classify the types of mass movement in Danyang Geopark (where various rock types are distributed) and analyzed the mechanical and hydraulic characteristics of landslide materials using a series of laboratory tests. Debris flows occurred in areas of limestone/marble, shale, and porphyroblastic gneiss, and limestone/marble landslides were distinguished from the others through the presence of karren topography. Soil tests showed that soil derived from weathered gneiss, which has a higher proportion of coarse grains, has a higher friction angle, lower cohesion, and larger hydraulic conductivity than soils from areas of limestone/marble, and shale. Rock failure mass movements occurred in areas of phyllite, sandstone, and conglomerate and were subdivided into plane failure, block-fall, and boulder-fall types in areas of phyllite, sandstone, and conglomerate, respectively. The shear strength of phyllite is much lower than that of the other types of rock, which have similar rock quality. The slake durability index of the conglomerate is similar to that of the other rock types, which have similar degrees of weathering, but differential weathering of the matrix and clasts was clearly observed when comparing the samples before and after the test. This study can help establish appropriate reinforcement and disaster prevention measures, which depend on the type of mass movement expected given the geological characteristics of an area.

• Journal of the Speleological Society of Korea
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• no.66
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• pp.59-66
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• 2005

The present writer have been engaged in research the Karst topography of Korea from the 1950's. Especially, I have studiedthe hollows indicated on topographical maps(1:5,000, 1:50,000) in library side by side with field survey. As the side by side with field survey. As the result, I came to a conclusion that all the hollows in limestone area are not always dolines. Based on case study, I classified the hollow landforms into 10 groups as follow. 1) Solution hollow 2) Volcanic hollow 3) Desertic hollow 4) Structural hollow 5) Meteoric hollow 6) Limnoic hollow 7) Minal hollow 8) Artificial hollow 9) Bursted hollow 10) Compound hollow I am asking advices of you all.

• Korean Journal of Plant Taxonomy
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• v.39 no.1
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• pp.1-3
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• 2009

We named and described Clematis calcicola J. S. Kim, a new species of Clematis sect. Atragene (Ranunculaceae) found in a limestone area of Mt. Deokhang, Korea. Clematis calcicola is distinguished from the other species of sect. Atragene by 1) sparsely dentate, glabrescent, and subcoriaceous leaflets and 2) smooth and thick sepals.

• The Korean Journal of Ecology
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• v.21 no.2
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• pp.139-149
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• 1998

The Catba national park (20$\circ$42'-20$\circ$54'N, 106$\circ$54'-107$\circ$09'E), which is a representative protected area in northeast Vietnam, was first investigated in terms of phytosociology of the Zurich-Montpellier School. 15 plant communities were identified from the seven vegetation types: Teetaria-Amoora gigantea community, Blechmum-Pitecellobium ferrugineum community, Impatiens-Dracaena cambodiana community, Rhizophora apiculata community, Avicenia marina community, Panicum repens community, Heterosmilax-Zanthoxylum nitidum community, Stachytarphyta jamaiensis-Bidens bipinnata community, microstegium vagans community, Dicranopteris linearis community, Randina-Sapium sebiferum community, Psidium gujava community, Elephantopus scaber community, and chirita aratformis community. Traditional pasturing and shifting agrie\culture by indigenous people in Catba national park were recognized as main disturbance regies, which have been far above sustainable levels. Ecological strategies for conservation and sustainable use on national park' ecosystem were proposed: (1) development of awareness program on sustainable life style of indigenous people, (2) establishment of multiple use module system of national park, (3) ecosystem monitoring of permanent ecological sites.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2005.04a
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• pp.405-407
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• 2005

To evaluate the main hydrogeochemical characteristics, river waters are investigated using element리 and isotopic compositions in South Korea. In this area, the chemical compositions are mostly classified into three groups; $Ca^{2+}-{HCO_3}^-$ type, $Ca^{2+}-Cl^{-}-{NO_3}^-$ type and $Ca^{2+}-{HCO_3}^{-}-Cl^{-}-{NO_3}^-$ type. These types are affected by two major factors: water-rock interaction and anthropogenic inputs such as sewage and fertilizers. Based on the values of ${\delta}^{18}O$ and ${\delta}D$, most of waters are originated from precipitation except two samples contaminated. The lithology and geography of basins mainly control the water chemistry. Elemental and isotopic compositions show that water chemistry are mainly controlled by three end members, especially by carbonate dissolution, and suggest that anthropogenic input affect the water chemistry. Also, three weathering sources are identified: silicates, dolomite and limestone.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.1041-1044
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• 2008

The addition of chemical inert filler in blended cement, such as limestone or chemical inert silica fume, will produce a physical effect on cement hydration. Due to the high surface area of inert filler in the mixtures, it provides sites for the nucleation and growth of hydration products, thus improving the hydration rate of cement compounds and consequently increasing the strength at early age. This paper proposes a model of hydration of Portland cement blended with chemical inert filler. This model considers the influence of water to cement ratio, cement particle size, cement composition and addition of chemical inert filler on hydration. The heat evolution, degree of hydration and porosity are obtained as accompanied results in hydration process. The prediction results agree well with experiment results.

• Economic and Environmental Geology
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• v.24 no.3
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• pp.309-318
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• 1991

Analysis for landslides was studied in framework of Chungju dam right abutment, 6.5km northeast of Chungju city. $5.5{\times}10^6m^3$ landslide materials were excavated during dam construction for safety of the Chungju dam. Geology of study area is composed mainly of meta sediments such as dolomitic limestone, quartzite and schist which are dipping toward the Nam Han river. Scanline survey of discontinuities was performed for slope stability, resistivity exploration was performed for the evaluation of potential failure plane, and direct shear strength test of rocks and soils was performed for the effect on landslide. Monitoring systems of tiltmeter, tensiometer, ground water observation hole and level monument were installed during dam construction and interpreted for the evaluation of slope instability. Kinematic solution of the geological structure and evaluation using safety factor for slope may prove the failure of the slope.

• Journal of environmental and Sanitary engineering
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• v.13 no.3
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• pp.19-29
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• 1998

The calcination reactivity of limestone and physical property changes of calcined lime were investigated with a temperature($720~1000^{\circ}C$ under atmospheric gas($N_2$, $CO_2$) conditions. The mechanisms of mass transport in a lime matrix were represented by the evaporation and condensation (${\gamma}=1.7$) at $1000^{\circ}C$ and the volume diffusion (${\gamma}=2.7$) at $800^{\circ}C$, which was obtained by the specific surface area of calcined lime with sintering conditions. Also, the effect of physical property on the reactivity of sulfation reaction was determined by the changes of pore size with $lime-SO_2$ reaction in this work. The initial sulfation rate of calcined lime increased with increasing temperature, whereas the capture capacity of $SO_2$ exhibited a maximum value at $900^{\circ}C$. The pore volume of sulfated lime was decreased with increasing sulfation time, but the major pores shifted to the distribution of larger size at a temperature of $850{\;}~{\;}1000^{\circ}C$. The mean pore size of sulfated lime based on pore volume decreased gradually at $1000^{\circ}C$; however, it increased with sulfation time up to 40 min and rapidly decreased thereafter.