• Proceedings of the Korea Concrete Institute Conference
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• 1994.04a
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• pp.169-173
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• 1994

Recently, the use of crushed stones is increased due to the shortage of natural aggregates. In the previous papers of part 1 and 2, we got the conclusions that some of crushed stones have the characteristic of alkali-silica reaction(ASR). And these reactions are influenced by the amount and type of alkali in cement. The purpose of this paper is how to prepare for the prevention against alkali-silica reaction. As a solution of problems, we have conducted the experiments of two methods. One was the replacement of innocuous aggregates instead of reactive aggregates, the other was the addition of various pozzolanic materials. As a result, we found that the expansion by alkali-silica reaction in mortar bar could be effectively decredsed by upper methods.

• Proceedings of the Korea Concrete Institute Conference
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• 1994.10a
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• pp.447-450
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• 1994

The chemical method and mortar-bar method for identification of the susceptibility to Alkali-Aggregate Reaction (AAR) was established as KS method by referencing the ASTM methods. However, the chemical method requires skilled chemical engineers and aggregates are tested in very severe condition, and on the other hand, the mortar-bar method needs a long time of 3 or 6 months. Judging from this circumstance that the use of crushed stones are increased due to the shortage of natural aggregates, the development and standardization of a new rapid test method is considered essential. The purpose of this paper is to research for the possibility to apply the rapid method, instead of the chemical method and the mortar-bar method with using the several domestic crushed stones.

• Proceedings of the Korea Concrete Institute Conference
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• 1993.10a
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• pp.103-107
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• 1993

The Alkali Aggregate Reaction(AAR), reported first by T. E. Stanton in 1940, is a reaction between certain siliceous aggregate and hydroxyl ions present in the pore fluid of a concrete. The damage of concrete structures, deteriorated by AAR, have been reported since using the crushed stones caused by the exhaustion of natural aggregates. This study was performed to investigate the AAR of crushed stones using chemical analysis, polarization microscope, XRD, chemical method(KS F 2545, ASTM C 289), mortar bar method(KS F 2546, ASTM C 227) and Scanning Electron Microscope(SEM) and Energy Dispersive X-ray Analysis (EDXA) of reaction products by AAR in mortar bar.

• Polymer(Korea)
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• v.32 no.3
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• pp.213-218
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• 2008

About 17% of historical properties in Korea were made of stones and most of them are exposed to weathering, as such that discoloring, cracking, and shattering occur from physical, chemical, mechanical, and biological effects due to outdoor placement. Proper treatments for conservation are necessary to prevent the weathering damage and to retain the original shape of stones. MMA, an acrylic monomer having low viscosity can be impregnated deep inside stones by consecutive compression and decompression process in a pressurized vessel. After the polymerization of MMA impregnate, the space inside of the stone was filled with PMMA. It is expected that water repellent and weather resistant properties will be improved because of the improved bonding of constituent materials in stones. In this study, moisture absorption, chemical resistance, and mechanical property of two domestic granites were examined after treating them with MMA for the purpose of determining the conservation value of this method that was possibly useful to the conservation of stone cultural assets.

• Korean Journal of Ichthyology
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• v.26 no.3
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• pp.202-211
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• 2014

Feeding ecology of Luciogobius guttatus (Flat-head goby) populations were investigated on the Youngjong, Incheon, Korea. In total, 257 individuals ranging from 13.4 to 57.5 mm standard length SL were analyzed. L. guttatus was studied in the Tide-pool from January 2010 to December 2010 monthly. The stomach contents of L. guttatus consisted mainly of Copepods and Brachyurans. Amphipods, Anomurans, Cumaceans, Macrurans, Insects and small stones were also observed. As a result, the benthic crustaceans were important food for this species. Harpacticoid spp. (Copepods) and Hemigrapsus spp. (Brachyurans) were major prey organisms for all fish size and seasons.

• Publications of The Korean Astronomical Society
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• v.28 no.2
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• pp.25-36
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• 2013

Chumsungdae is an ancient astronomical observatory whose main role was doing 'chunmoon'. It was administrate by a royal advisory agency on state affairs. The observers observed the heaven on the observatory platform, recorded peculiar events, and watched and interpreted the signs displayed in the heaven. Chumsungdae is an stonemasonry which represents almanac principles with its peculiar shapes and the numbers of strata and stones. The numbers were thoroughly invented to match exactly the almanac constants. Chumsungdae is comprised largely of three main parts, namely the square base, the stratified cylindrical body, and the top #-shaped stonework, and the total number of stones is 404. The number of the strata (27) and the height of the cylindrical body (27 尺) stand for the days in a sidereal month (27.3 days), which implies that the motion of the Moon with respect to the stars was given more priority than to the Sun at that time of geocentricism. And the cylindrical body was thoroughly designed to consist of 365 stones, which is of course the number of days in a solar year. In addition, there are 12 strata each under and above the south entrance and this in sum makes the 24 divisions of the year. Also there is 182 stones below the 13th stratum and this represents the number of days in the winter ~ summer solstice period, and the rest 183 stones the vice versa. The #-shaped top stonework was aligned in such a way that one of the diagonals points the direction of sunrise on the winter solstice. The square base also layed with the same manner. The south entrance was built 16 degrees SE, and the upright direction of the right pillar stone coincides with the meridian circle. This was a kind of built-in standard meridian circle facilitating the observations. In a symbolic sense, Chumsungdae was thought as the tunnel reaching the heaven, where the observers wished to be enlightened with the signs and inspirations in need. With the craftsmanship and skill, the builder reinforced the stratified cylindrical body with two sets of #-shaped beam stones, piercing at a right angle at 19th ~ 20th and 25th ~ 26th strata. Likewise, by placing the double #-shaped stonework with 8 beam stones on the platform of the observatory, both the stability of the stonemasonry and a guard rail for the nightly observers were securely provided.

• Carbon letters
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• v.21
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• pp.81-85
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• 2017

The objective of this study is the removal of chromium from tannery wastewater by electrosorption on carbon prepared from lignocellulosic natural residue "peach stones' thermally treated. The followed steps for obtaining coal in chronological order were: cleaning, drying, crushing and finally its carbonization at $900^{\circ}C$. The characterization of the carbon material resulted in properties comparable to those of many coals industrially manufactured. The study of the dynamic adsorption of chromium on the obtained material resulted in a low removal rate (33.7%) without applied potential. The application of negative potentials of -0.7 V and -1.4 increases the adsorption of chromium up to 90% and 96% respectively. Whereas a positive potential of +1.4V allows desorption of the contaminant of 138%.

• Proceedings of the Korean Institute of Interior Design Conference
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• 2006.05a
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• pp.272-277
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• 2006

The purpose of this study is to draw out the features of expressions about Nature in Korean interior design, because the Nature has been being very important theme in the interior space. So, the 68 cases of domestic famous interior designers' works during last ten years were selected from authorized design magazines like as INTERIORS, MARU and so on. And next, the cases were analysed in according to interior image style, design elements used for effect of Nature and the direction of expression(directly or indirectly), As the results, composite expressions with a few elements were found in modern, hi-tech, elegant, minimal and casual styles, while direct expressions with many elements were found in natural and ethnic styles. And main elements for effect of Nature were trees and stones. Among many elements, water and stones became more important elements after 2000 than before. In the meantime the use of composite expressions was being increased and so appeared even in natural and ethnic styles.

• Journal of Korean Society of Rural Planning
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• v.3 no.2
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• pp.81-89
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• 1997

Still today, many streams are channelized and embanked in Korea. On the other hand, some urban streams are being restored to their natural shapes by landscape planners. It would be better to improve rural streams in a way that would not require restoration in later days. Then, one important question is what kind of embankments the residents prefer for what reasons. Five simulated photos showing from very natural to artificial embankments were used in surveying 90 residents of three villages. Major findings are ; 1. Residents regard safety(from flooding) is the most critical factor to be considered in selection of stream bank materials. 2. They think ideal materials are natural stones or concrete blocks as they look tidy. Concrete retaining walls or vegetated natural slopes are not regarded good. 3. The most preferred material is concrete retaining wall, and the least preferred is vegetated natural slope. They prefer concrete retaining wall which they do not think an ideal material, because it will make a safe bank. 4. Natural stone bank is most preferred for its apperance, and vegetated natural slpoe is most disliked as it may collapse and as it does not look clean.

• Journal of Technologic Dentistry
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• v.35 no.4
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• pp.321-332
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• 2013

Purpose: This study was examined the characteristics of bacteria isolated from the dental stone that is made ??in the dental laboratory. Methods: 104 dental stones samples were collected from the 4 dental laboratory. Characteristics of bacteria were investigated by microorganism isolation culture method using a Blood Tryptic Soy Agar(TSA) medium. Results: The detected various bacteria was confirmed as pathogenic bacteria, non-pathogenic bacteria and natural bacteria. The isolated bacterial number was confirmed $2.9{\times}10^3CFU$ and maxium bacterial number of $3.0{\times}10^4CFU$. Conclusion: Therefore, infection prevention education is required, it must be to live up the hand-washing and wear protective clothing to protect themselves when working in a dental laboratory.