• Proceedings of the Korea Concrete Institute Conference
• /
• 2010.05a
• /
• pp.323-324
• /
• 2010

The purpose of this study was to investigate alkali-silica reaction of accelerating agents in shotcrete. The test was performed with accelerating agents (aluminate, alkali-free, cement based mineral admixture) in the Type I cement. As a test result, using the nonreactive aggregates, detrimental expansion due to alkali-silica reaction doesn't occurred regardless of equivalent alkali contents of accelerating agent.

• Journal of the Mineralogical Society of Korea
• /
• v.16 no.4
• /
• pp.295-305
• /
• 2003

This study aims to provide the physicochemical properties of three kinds of organo­smectites which can be diversely used in industries. Some properties of them were compared with Na­smectite. Three kinds of organo­smectites such as Hexadecyltrimethylammonium(HDTMA), Benzyldimethyltetradecylammonium(BDTDA), and Cetylpyridinium(CP) exchanged smectites were manufactured for this study. Three types of organo­smectites showed the alkaline character(pH 9), very low swelling property and viscosity, and a fast flocculation behavior because of strong hydrophobic property in contrast to hydrophilic Na­smectite. Three organo­smectites showed the strong interlayer expansion with basal spacing from $19\AA$ to $23\AA$ compared with the Na­smectite of about 12 $\AA$. Organic cations such as HDTMA, BDTDA, and CP exchanged into smectite were completely decomposed in the temperature range from $250^{\circ}C$ to $400^{\circ}C$. Generally, three organo­smectites showed the similar mineralogical, physicochemical and thermal properties. But their properties are quite different from Na­smectite. Considering economically, CP exchanged smectite would be used for the diverse utilization field in the future time.

• The Korean Journal of Pesticide Science
• /
• v.2 no.1
• /
• pp.70-78
• /
• 1998

This study was conducted to investigate the adsorption-desorption characteristics of herbicide paraquat on clay minerals, humic materials, and soils under the laboratory conditions. Adsorption time of paraquat on clay minerals was faster than organic materials and soils. Adsorption amount on montmorillonite, 2:1 expanding-lattice clay mineral, was largest among the adsorbents tested. The adsorption capacity of paraquat was approximately 21 % of cation exchange capacity in soils, 45.1 % in kaolinite, and 80.6% in montmorillonite. Humic materials, humic acid and fulvic acid isolated from soil II, adsorbed larger amount of paraquat than kaolinite and soils. Distribution of tightly bound type of paraquat was larger in clay mineral and soils but loosely bound type was larger in humic acid and fulvic acid. In oxidized soil, the adsorption amount of paraquat was decreased to 85.1-95.5% of original soils. Distribution of unbound and loosely bound type of paraquat was decreased in oxidized soil but tightly bound type was increased. The competition cations decreased paraquat adsorption on humic materials and soils but not affected on montmorillonite. No difference was observed as the kinds of cations. In cation-saturated adsorbents, the adsorption amount was decreased largely in humic materials and soils but decreased a little in montmorillonite. The tightly bound type of paraquat in all adsorbents was not desorbed by pH variation, sonication, and cation application but loosely bound type was desorbed. However, the desorption amount was different as a kinds of adsorbents and desorption methods.

• The Microorganisms and Industry
• /
• v.15 no.2
• /
• pp.54-56
• /
• 1989

19세기 초기까지 인류가 사용해왔던 약물들은 동식물및 광물질 기원의 물질을 단순하게 처리한 것들이었다. 그 이후 화학의 발달및 필수적인 생리활성 검색법의 개발에 의해 비로소 현대적인 의미의 약물학(Pharmacology)의 시대가 열리게 되었다. 화학의 발달에 의해 오래전부터 사용되던 약제 중의 유효성분의 분리, 정제, 확인과 신물질의 합성이 가능해졌으며, 생리활성 검색법의 개발에 의해 유효성의 측정및 약물의 생체내 작용기전의 확인이 연구될 수 있었다. 일단 이러한 필수적인 도구와 테크닉이 주어지자 신약개발은 관련분야의 급속한 발달과 보조를 같이하여 가속적으로 발전하였으며 여기에 의약품 제조업의 성장이 자극제로 작용하였다. 그 결과 신개발약물의 양적인 팽창, 약물에 의해 조절될 수 있는 질병의 증가 및 약물작용기전의 이해등의 성과가 얻어질 수 있었다. 신개발약물의 수는 세계 제2차대전 종료후 10여년 사이에 최대에 달하였으나 그후 신약의 허가에 수반되는 법령의 강화에 따라 감소하기 시작하여 현재는 거의 일정한 수준을 유지하고 있다.

• Economic and Environmental Geology
• /
• v.34 no.1
• /
• pp.1-12
• /
• 2001

The crystal structure of biotite-1M from Bancroft, Ontario, was determined by Rietveld refinement method using high-resolution neutron powder diffraction data at -26.3$^{\circ}C$, 2$0^{\circ}C$, 30$0^{\circ}C$, $600^{\circ}C$, 90$0^{\circ}C$. The crystal structure has been refined to a R sub(B) of 5.06%-11.9% and S (Goodness of fitness) of 2.97-3.94. The expansion rate of a, b, c unit cell dimensions with elevated temperature linearly increase to $600^{\circ}C$. The expansivity of the c dimension is $1.61{\times}10^{40}C^{-1}$, while $2.73{\times}10^{50}C^{-1}$ and $5.71{\times}10^{-50}C^{-1}$ for the a and b dimensions, respectively. Thus, the volume increase of the unit cell is dominated by expansion of the c axis as increasing temperature. In contrast to the trend, the expansivity of the dimensions is decreased at 90$0^{\circ}C$. It may be attributed to a change in cation size caused by dehydroxylation-oxidation of $Fe^{2+}$ to $Fe^{3+}$ in vacuum condition at such high temperature. The position of H-proton was determined by the refinement of diffraction pattern at low temperature (-2.63$^{\circ}C$). The position is 0.9103${\AA}$ from the O sub(4) location and located at atomic coordinates (x/a=0.138, y/b=0.5, z/c=0.305) with the OH vector almost normal to plane (001). According to the increase of the temperature, $\alpha$* (tetrahedral rotation angle), $t_{oct}$ (octahedral sheet thickness), mean distance increase except 90$0^{\circ}C$ data. But the trend is less clearly relative to unit cell dimension expansion because the expansion is dominant to the interlayer. Also, ${\Psi}$ (octahedral flattening angle) shows no trends as increasing temperature and it may be because the octahedron (M1, M2) is substituted by Mg and Fe.

• Journal of the Korean Geotechnical Society
• /
• v.37 no.11
• /
• pp.83-92
• /
• 2021

In this study, effective porosity measurement, electron microscope (SEM) observation, X-ray diffraction analysis (XRD), slaking, swelling, and unconfined compression strength according to water immersion were analyzed to evaluate the properties of mudstone with high porosity in Pohang. As a result of the test for 16 square samples (5 cm), the effective porosity was 14.67% on average, higher than porosity of general mudstone, and electron microscope observation confirmed that the porosity was actually high. As a result of X-ray diffraction analysis, the swelling clay mineral content was 2.3~4.1%, which was lower than the results of previous studies in Pohang. The slake durability index was 37.73~87.73%, showing low to medium durability, which was lower than the results of previous studies. It was confirmed that the swelling property rapidly expanded to 1.79~1.82% of maximum swelling strain in the major axis direction for 30 minutes. As the properties of decreasing the unconfined compression strength according to water immersion, the samples rapidly weathered after 10 minutes of water immersion, and the strength decreased. It was confirmed that the results of previous studies related to mudstone in Pohang were different. This is judged to be due to the high porosity of mudstone in study.

• Journal of the Mineralogical Society of Korea
• /
• v.17 no.2
• /
• pp.147-155
• /
• 2004

Anion adsorption properties of organobentonites modified by two cationic polymers, hexadecyltrimmethylammonium (HDTMA) and cetylpyridinum (CP), were investigated. The organobentonites showed the significant expansion of basal spacing to 42.0 $\AA$ at room temperature. The adsorption experiments were conducted for the 0.2 g of organobentonites with 40 mL solutions of various concentrations of anions such as nitrate, sulfate and phosphate. As a result, the organobentonites showed excellent adsorption capacities for those anions whereas untreated bentonite showed very low adsorption capacity. Adsorption rate of HDTMA-bentonite was about 90% for 100 mg/L solutions of nitrate and phosphate, and that of CP-bentonite was 97% for 100 mg/L solution of nitrate. Adsorption behaviors were slightly different for the different organobentonites and anions. Both organobentonites showed relatively higher adsorption rate for nitrate and phosphate than sulfate. Therefore, these organobentonites showing high anion adsorption capacities can be used far the removal of deleterious anions in the treatment of environmental pollution.

• Journal of the Korea Institute of Building Construction
• /
• v.11 no.4
• /
• pp.345-352
• /
• 2011

The purpose of this study was to investigate the expansion of alkali-activated mortar based on ground granulated blast furnace slag containing reactive aggregate due to alkali-silica reaction. In addition, this study was particularly concerned with the behavior of these alkaline materials in the presence of reactive aggregates. The experimental program included expansion measurement of the mortar bar specimens, as well as the determination of the morphology and composition of the alkali-silica reaction products by using scanning electron microscopy(SEM), and energy dispersive x-ray(EDX). The experiment showed that while alkali-activated ground granulated blast furnace slag mortars showed expansion due to the alkali-silica reaction, the expansion was 0.1% at Curing Day 14, showing that it is safe. After the accelerated test, SEM and BEM analysis showed the presence of alkali-silica gel and rim around the aggregate and cement paste. According to the EDX, the reaction products decreased markedly as alkali-activated ground granulated blast furnace slag was used. In addition, for the substitutive materials of mineral admixture, a further study on improving the quality of alkali-activated ground granulated blast furnace slag is needed to assure of the durability properties of concrete.

• Journal of the Mineralogical Society of Korea
• /
• v.19 no.4 s.50
• /
• pp.277-289
• /
• 2006

This study was carried out to find a new material having high removal efficiency for the harmful red tide. C. polykrikoides grow very fast and accumulate into dense and visible patches near the surface of the seawater ('Water bloom'). Some mineral medicines and Hwangto (reddish soil consist of clay minerals and Fe-oxides) were used in this study to remove C. polykrikoides. The pre-determined sprinkling ratio of mineral vs. seawater which contains approximately 5,000 cells/mL of C. polykrikoides was 10 g/L. In order to quantify the removal efficiency, the density of living cells was measured by counting with the Intervals of 0, 10, 30, and 60 minutes after sprinkling. Five Hwangtos feom different localities were examined in this study. It is found that a material with a high concentration of Fe and Al was the most effective to remove C. polykrikoides. After the sprinkling of the Hwangto showing the best removal efficiency in the test, 99% of total algaes were found to be eliminated within 60 minutes. Jeokeokji showed the highest removal efficiency among clay mineral medicines(92% removal efficiency after 60 minutes), and the rests in decreasing order are as follows: Gamto (91%) > Baekseokji (89%) > Hydromica (81%). In addition, Fe-oxide mineral medicine similarly looking as fine-grained earthy Daejaseok showed 100% removal efficiencyafter 30 minutes, and Wooyoeryang, 95% after 60 minutes. It is noted that even little addition (1 g/L) of Daejaseok, 10% of Hwangto concentration into seawater showed the removal efficiency of 100% after 60 minutes. From the results, it could be concluded that the fine-grained earthy Daejaseok was the most effective natural mineral medicine to remove the C. polykrikoides from seawater. Under the microscope the removal mechanism was found to be activated in the following order: adsorption, swelling of chain colony, chain colony crisis and algaecide.

• Journal of the Korean Geotechnical Society
• /
• v.19 no.6
• /
• pp.23-29
• /
• 2003

In this paper, effects of the acidification of ground and the chemical additive materials-ferric oxide, calcium chloride and calcium sulphate on the compressibility characteristics of the marine clay treated with quick lime were investigated. The rapid inflection point method was carried out. Results showed that the compression index of the untreated marine clay increased as the pH of pore water decreased. Also, the preconsolidation pressure, the coefficient of consolidation and the coefficient of permeability of the untreated marine clay decreased with pH of pore water. In the case of the marine clay treated with the quick lime-calcium chloride, the compression index decreased and the coefficient of consolidation and the coefficient of permeability increased. Specially, the preconsolidation pressure of sample treated with the quick lime-ferric oxide was higher than that of another samples.