• Journal of the Korea institute for structural maintenance and inspection
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• v.17 no.4
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• pp.66-74
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• 2013

In this study, corrosion potential ($E_{corr}$), corrosion rate, and polarization resistance were measured aimed at inorganic inhibitors (passive film type) and organic inhibitors (absorption type). The experiment was conducted using potentiostat for the variable molar ratio and chloride ion concentration of the components of inhibitors in an aqueous solution of saturated calcium hydroxide targeting corrosion. As a result, it was possible to ensure an anticorrosive performance of at least a 1.2 molar ratio of inorganic inhibitors. Also, the organic inhibitors ensured the prevention of the anticorrosive performance of at least about a 0.3 molar ratio. It also showed the tendency that between polarization resistance and corrosion rate, Ecorr and corrosion rate is inversely proportional to the linear. Conversely, the tendency between polarization resistance and Ecorr is proportional to the linear. Also, a distinct difference in organic and inorganic inhibitors' relationship to Ecorr, corrosion rate, and polarization resistance was not shown.

• KOREAN POULTRY JOURNAL
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• v.3 no.7 s.21
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• pp.58-63
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• 1971

국내에서 생산되는 배합사료의 품질을 비교하기 위하여 1969년부터 3년간 전국에서 323점의 배합사료 샘플을 수집하여 일반 조성분 및 칼슘인 함량을 분석해 본 결과 다음과 같은 결론을 얻었다. (1) 모든 성분에 있어서 같은 사료라도 제조하는 회사에 따라 그 함량의 변이가 심하며 산란사료의 경우에는 생산하는 종류의 계열화가 필요하다고 생각된다. (2) 수분 함량은 대개의 경우 13$\%$이하이나 일부 15$\%$ 이상으로 높은 것도 있었다. 조단백질 함량이 지나치게 높은것도 있었으나 다소 부족한 감이 있는 것도 상당수에 달했으며 대체로 조섬유 함량은 허용범위내에 들어갔으나 더러는 공정규격의 상한치를 넘는 것도 있었다. 산란계 사료에 있어서 조회분 함량과 Ca의 함량을 상관시켜 보면 공정규격 상한치의 제조정이 요청된다. (3) 초생추, 중추 및 대추 사료에 있어서는 Ca함량이 1.2$\%$이상인 것이 많았고 산란계 사료에 있어서는 2.75$\%$이하인 것이 상당수 있어서 앞으로 칼슘의 함량조절에 크게 주의를 해야 된 것 같다. 이런 점에서 보면 유통되는 패분의 선택에 신경을 써야 할것으로 본다.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2021.05a
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• pp.213-214
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• 2021

External insulation method is used to conserve energy of buildings. However, the current external insulation method uses organic insulating materials to become a diffusion path in case of fire. In this study, the purpose of this study is to provide basic data on the required performance of the plastering material according to the CaCO₃ powder addition of the finishing material of the external insulation method. In Figure 1, when powder was added, the adhesion strength decreased by 30% to 35% at 10% and 0% to 50% at 20% compared to Plain. In Figure 2, the moisture permeability increases approximately twice when powder is added. The results for the water absorption coefficient are shown in Figure 3.

• Journal of Biomedical Engineering Research
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• v.19 no.5
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• pp.449-454
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• 1998

It is well known that new tissue or blood vessel is grown into a porous calcium phosphate ceramics used as a bone graft substitute due to their excellent biocompatibility. In this study, the most chemically stable porous $\beta$-crystalline form in various forms of calcium metaphosphate, Ca(PO$_3$)$_2$is prepared by the controlled thermolysis of monocalcium phosphate, Ca(H$_2$PO$_4$)$_2$.The diameter of cylindrical pores formed during cooling was controlled by a holding time at the melting point of a monocalcium phosphate and by the change of a crystallization temperature, to obtain the most appropriate size (about 200$\mu$m) of pores for the application of bone substitutes and matricuts. It was observed that the increasing holding time at the melting point of monocalcium phosphate results in the decreases of cylindrical pore sizes.

• Journal of the Korea Institute of Building Construction
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• v.17 no.3
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• pp.253-260
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• 2017

As global warming became a worldwide issue, a significant effort has been made on the development of technology related to $CO_2$ capture and storage. Geologic sequestration of $CO_2$ is one of those technologies for safe disposal of $CO_2$. Geologic sequestration stores $CO_2$ in the form of supercritical fluid into the underground site surrounded by solid rock, and concrete is used for prevention of $CO_2$ leakage into the atmosphere. In such case, concrete may experience severe damage by attack of supercritical $CO_2$, and especially in contact with underground water, very aggressive form of carbonation can occur. In this work, to prevent such deterioration in concrete, calcium phosphates were added to the portland cement to produce hydroxyapatite, one of the most stable mineral in the world. Temperature rise, viscosity, set and stiffening, and strength development of cement paste incorporating three different types of calcium phosphates were investigated. According to the results, it was found that the addition of calcium phosphate increased apparent viscosity, but decreased maximum temperature rise and 28 day compressive strength. It was found that monocalcium phosphate was found to be inappropriate for portland cement based material. Applicability of dicalcium and tricalcium phosphates for portland cement needs to be evaluated with further investigation, including the long term compressive strength development.

• Ceramist
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• v.9 no.2
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• pp.56-60
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• 2006

• Proceedings of the Korean Ceranic Society Conference
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• 2003.04a
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• pp.207.2-207
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• 2003

• Resources Recycling
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• v.5 no.3
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• pp.65-72
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• 1996

Colloidal calcium wrbonate(diametcr 0.02-0 09 m~wja s developed to maintain the mamenl of pnriide formatio~>w ~lhoutsurlace trealment. The control factors of particle size and optimum condiliuna for compound fam*tition has not bccn studiedyet. This shldy war aimed at developing a method fur compounding colloidal calcium carbonfcte to cnl~hol cubic calciumcarbonate, and then compounding the b-o types oI precipitated calcium wrbonatc under optimum wndilrans Calc~umhydroxide was calcinated at 1, lWC far two hours, md then hydrated for 30 minutes at t i i O rprn and ambiznt temperahlle.Two-liter suspension was subjected to the contact with carbon dioxide at l5"C, 600 ipxn and C0= injection in the rate of 1 Umin Two types of dcium carbonate(cuhic calcium carbonatc(0 24.9 pm) md collnidd calcium mhnnate (0.02-0 09 pm))were compounded by "wing the concentrations of calcium oxide and ihe suspension were compounded. It was found that theoptimum concentrations of each suspensions were 5 wt % and 2.5 \I*.% respectively. ' h c key control factor af thc parlicle slzcdislribution was the concenkation al the suspension. The size of compounded particles was measured by a Zcla S k r 'fieaverage particle size of the cubic calcium carbonate aas 223.4 nm(0.223 pm), and that of thc colloidal a~lciumc arbonate was93.6 nm (0.093 km). Ihe particle sizc was evenly cantlolled on a stdblc basis in an H, O reaction system.asis in an H, O reaction system.

• Magazine of the Korea Concrete Institute
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• v.6 no.4
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• pp.141-152
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• 1994

The results of an experimental study on the development and the evaluation of lightweight and high strength composites utilizing by-products and calcium silicates for construction materials are presented in this paper. The composites using early strength portland cement, by-Products( f1y ash, silica fume), silica powder, quick lime, gypsum, A1 powder and fibers(PAN-derived CF, alkali-resistance GF) were prepared using various mixing conditions. As the test results show, PAN-derived CF and alkali-resistance GF were suitable for rein-forcing fiber of the composites. And the mechanical properties,such as compressive tensile flexural strength, and toughness of Lt. Wt. fiber reinforced calcium silicates cement comp-osites were improved by increasing the fly ash and silica fume contents, and fiber contents, especially by increasing fiber contents the toughness of the composites were remarkably in-creased. Also, compressive tensile flexural strength,and toughness of the composites rein-forcing PAN-derived CF were higher than those of the composites reinforcing alkali-resistance GF..

• Resources Recycling
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• v.25 no.5
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• pp.14-27
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• 2016

Theoretical reviews of integrated gasification combined cycle one of the clean coal technologies and trends in the study and technology development for high temperature desulfurization sorbents were investigated. Reactivity, durability and abrasion resistance is an important key for development of high temperature desulfurization sorbents, the kind of things include calcium, zinc, manganese, iron and copper-based sorbents. Current status of high temperature desulfurization sorbents, manufacturing techniques of zinc-based sorbent in advanced countries has commercialized. In case of Korea, various research studies are underway to commercialize the Zn and non Zn-based high temperature desulfurization sorbents to cheaper and superior capability using various supports.