• Journal of the Korea institute for structural maintenance and inspection
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• v.16 no.6
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• pp.26-33
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• 2012

This paper reported on the effect of blended activator on the physical properties of alkali-activated slag mortar. Five different activators(caustic alkalis) were used: sodium hydroxide(NaOH, A Case), calsium hydroxide($Ca(OH)_2$, B Case), magnesium hydroxide($Mg(OH)_2$, C Case), aluminum hydroxide($Al(OH)_3$, D Case), and potassium hydroxide(KOH, E Case). We blended five caustic alkalis with sodium carbonate($Na_2CO_3$). The dosage of five caustic alkalis was 3M and sodium carbonate was 1M, 2M and 3M. The result of flow and setting time was decrease as the dosage of sodium carbonate increase. But the compressive strength was increase as the dosage of sodium carbonate increase. It was shown that there is a good effect of blended caustic alkalis with sodium carbonate in alkali-activated slag mortar.

• Journal of the Korea Institute of Building Construction
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• v.23 no.4
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• pp.349-358
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• 2023

This research aimed to enhance the initial strength of concrete that is mixed with ground granulated blast furnace slag, as well as to fortify its resistance to carbonation and chloride ion permeation. To achieve this, alkaline aqueous, produced through the electrolysis of potassium carbonate, was employed as the mixing water in the preparation of concrete. To substantiate the increment in initial strength, compressive strength measurements of the concrete were executed. Additionally, an accelerated carbonation test and a chloride ion permeation resistance test were undertaken. The results confirmed that the initial strength of the concrete, which utilized electrolysis alkaline aqueous as mixing water, exhibited an improvement in comparison to concrete mixed with conventional water. It was also verified that both carbonation resistance and chloride ion permeation resistance showed enhancements.

• Journal of the Korean Ceramic Society
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• v.39 no.12
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• pp.1197-1202
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• 2002

In order to develope the porous $K_2Ti_6O_13$ whisker preform with good strength, the pore characteristics and compressive strength were investigated as a function of spark plasma sintering temperature. As a result, high porous whisker preform were successfully fabricated by sintering at 900∼950${\circ}C$ for 10 min under a pressure of 40 MPa, heating rate of 50${\circ}C$/min and on-off pulse type of 12:2. The whisker preform prepared under above optimum condition showed relatively high compressive strength of 174∼266 MPa, despite of high porosity ranging from 15% to 37%. This improvement in strength was considered to be mainly due to the spark-plasma discharges and the self-heating action between whiskers. The compressive strength of whisker preform, fabricated at sintering temperature less than 900${\circ}C$, showed 80∼100 MPa. This is low strength level less than one half times compared with whisker preform fabricated at 900∼950${\circ}C$. The whisker preform fabricated at 1000${\circ}C$ showed the highest compressive strength of 523 MPa, but resulted in low porosity of ∼5%. Based on above results, it was considered that spark plasma sintering was an effective method for developing high strength and porosity of whisker preform.

• Journal of the Korean Society for Precision Engineering
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• v.21 no.4
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• pp.5-11
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• 2004

생체 시스템은 수많은 세포들로 구성되어 있다. 일반적으로 세포막은 단백질과 지방의 혼합체로 구성되어 있으며 두께는 7.5-10nm 정도이다. 단백질은 지방과 함께 세포막을 통한 물질의 이동을 제어하는 역할을 한다. 특히 지방층은 지방에 잘 용해되는 산소나 탄산가스 등은 잘 통과시키지만, 지방에 잘 용해되지 않는 나트륨, 칼륨, 칼슘, 글루코스, 아미노산 등은 지방층 내부에 삽입되어 있는 단백질에 의해 조절된다.(중략)

• Journal of the Korea Concrete Institute
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• v.24 no.6
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• pp.745-752
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• 2012

This paper studies the effect of the compressive strength for combined alkali-activated slag mortars. The effect of activators such as alkali type and dosage factor on the strength was investigated. The alkalis combinations made using five caustic alkalis (sodium hydroxide (NaOH, A series), calcium hydroxide ($Ca(OH)_2$, B series), magnesium hydroxide ($Mg(OH)_2$, C series), aluminum hydroxide ($Al(OH)_3$, D series), and potassium hydroxide (KOH, E series)) with sodium carbonate ($Na_2CO_3$) were evaluated. The mixtures were combined in different dosage at 1M, 2M, and 3M. The study results showed that the compressive strength of combined alkali-activated slag mortars tended to increase with increasing sodium carbonate. The strength of combined alkali-activated slag mortars was better than that of control cases (without sodium carbonate). The result from scanning electron microscopy (SEM) analysis confirmed that there were reaction products of calcium silicate hydrate (C-S-H) and alumina-silicate gels from combined alkali-activated slag specimens.

• Applied Chemistry for Engineering
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• v.8 no.3
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• pp.446-453
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• 1997

The initial product was prepared by heating for 3 hrs at $1000^{\circ}C$ using a mixture of the rutile sand and industral $K_2CO_3$ in the molar ratio 2.0. And the intermediate product, fibrous potassium tetratitanate of layer structure, was obtained by the boiling water treatment of 10hrs for initial product using the calcination method. Also $KHTi_4O_9{\cdot}1.1H_2O$ was synthesized by ion exchange reaction through the acid treatment for 30 min at 0.005M HCl solution and then $K_2Ti_8O_{17}$ whisker of $length=10{\mu}m$, $diameter=0.2{\mu}m$ was synthesized by heat treatment at temperature range of $400{\sim}600^{\circ}C$.

• Journal of the Korean Geotechnical Society
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• v.29 no.4
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• pp.45-56
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• 2013

In this study, a blast furnace slag with latent hydraulic property is used to cement granular soils without using Portland cement. When the blast furnace slag reacts with an alkaline activator, it can cement soils. The effect of amounts of blast furnace slag and types of alkaline activator on soil strength was investigated for resource recycling. Four different amounts of slag and six different activators (two naturals and four chemicals) were used for preparing specimens. The specimens were air-cured for 3 or 7 days and then tested for unconfined compressive strength (UCS). The UCS of cemented sand with slag increased, in the order of specimens mixed with potassium carbonate, calcium hydroxide, sodium hydroxide and potassium hydroxide. Chemical alkaline activator was better than natural alkaline activator. The maximum UCS of 3-days cured specimens was 3 MPa for 16% of slag with potassium hydroxide, which corresponded to 37% of one with 16% of high-early strength portland cement. As the amount of slag increased, the UCS and dry density of a specimen increased for all alkaline activator cases. As the curing time increased from 3 days to 7 days, the UCS increased up to 97%. C-S-H hydrates were found in the cemented specimens from XRD analyses. Cement hydrates were more generated with increasing amount of slag and they surrounded sand particles, which resulted in higher density.

• Applied Chemistry for Engineering
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• v.5 no.3
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• pp.478-500
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• 1994

The preparation of potassium hexatitanate whisker by flux method was investigated. In this study, 8 types synthesis of flux such as $V_2O_5$, $Bi_2O_3$, $B_2O_3$, $Pb_3O_4$, KCl, $K_4P_2O_7$, $K_2WO_4$ and $K_2MoO_4$ were tested to find a suitable flux for the synthesis of potassium hexatitanate whisker. Effects of various reaction variables such as reaction temperature, time, $TiO_2$ mole ratio to $K_2CO_3$, flux mole ratio to the mixture of $K_2CO_3$ and $TiO_2$, and slow-cooling treatment on the crystallization of potassium hexatitanate whisker were investigated. $K_2MoO_4$ and $K_2WO_4$ were better flux than others tested for the synthesis of potassium hexatitanate. In the presence of $K_2MoO_4$ or $K_2WO_4$ flux, the optimum condition for the synthesis of potassium hexatitanate whisker was that reaction temperature of $1000{\sim}1100^{\circ}C$, reaction time of 5 hours, $TiO_2$ mole ratio to $K_2CO_3$ of 6.0, and flux mole ratio to mixture ($K_2O+nTiO_2$) of 4.0. Slow-cooling treatment showed good effect on the growth of long fibrous potassium hexatitanate.

• Journal of the Korean Ceramic Society
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• v.42 no.4
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• pp.282-286
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• 2005

Leucite crystal has been utilized for dental porcelain due to its high thermal expansion coefficient to meet its counter metal side. Many industrial applications of leucite from the incongruently melting of potassium feldspar are used and its minimum temperature of crystallization is $1150^{\circ}C$. This study aimed to get leucite crystal from lower temperature through congruently melting, and the starting materials are taken from K-feldspar mainly, and aluminum hydroxide and potassium carbonate are additionally supplied to meet stoichiometry of leucite. We report that the leucite crystal can be synthesized in congruently melting from the temperature $950^{\circ}C$ through solid-state sintering with k-feldspar, potassium carbonate and aluminum hydroxide.

• Proceedings of the Membrane Society of Korea Conference
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• 1997.10a
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• pp.61-64
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• 1997

1. 서론 : 적절한 이산화탄소의 분리는 지구온난화의 가속현상을 늦출 수 있을 뿐만 아니라 각종 탄화수소가스의 원료로 분리 정제된 이산화탄소를 재이용할 수 있으므로 경제적으로 매우 중요하다. 이산화탄소 분리에 사용되던 기존 공정들의 단점을 보완할 수 있는 대체방안으로 최근에 개발되기 시작한 것이 소수성의 다공성 고분자 분리막(hydrophobic porous ploymeric membrane) 방법인데, 이는 모듈의 유효 막 표면적이 상대적으로 크고 기체와 액체의 흐름을 독립적으로 제어할 수 있으므로 범람 등의 현상이 없으나 막 자체의 저항이 비교적 큰 단점을 가지고 있다. Qi와 Cussler는 이러한 특성을 가지는 중공사막 모듈에서의 기-액 흐름에 대한 물질전달 상관관계식을 얻었으며[1], Karoor 등은 여러 가지 중공사막 모듈을 사용하여 순수물과 diethanolamine(DEA) 등의 흡수제에 대한 이산화탄소의 물질전달 거동을 수치모델과 실험을 통하여 고찰하였다[3]. 또한 중공사막 접촉기의 실제적 응용에 대하여 Matsumoto 등은 화력발전소에서 발생하는 연소가스 내의 이산화탄소 흠수에 대한 연구를 수행하였다[4]. 본 연구에서는 중공사막 접촉장치를 사용하여 흡수제를 순수물과 탄산칼륨($K_2CO_3$)을 사용했을 경우의 이산화탄소의 분리 거동을 수치모델과 실험을 통하여 고찰하였다. 수치모델의 경우 이전까지의 연구가 반응이 없는 경우나 반응식을 간략화시킨 경우에 한정되었는데 비하여, 반으이 있는 경우 각각의 반응물질들의 거동을 고려한 반응식을 유도하여 해를 구하고자 하녔다.