• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2015년도 추계 학술논문 발표대회
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• pp.47-48
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• 2015

Recycled aggregate used in a site is strong alkali due to calcium hydroxide attached on its surface. Accordingly, many environmental problems arise. Therefore, as basic research to reduce pH of recycled aggregate, this study tries to reduce the strong alkalinity of recycled aggregate by using mixture solution based on sodium phosphate and ammonium chloride. As a result, original aggregate has the strong alkalinity of pH 11.23, whereas pH of recycled aggregate immersed in mixture solution decreased as more mixture rate increased, and mostly pH 9.8 or less was found.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2016년도 추계 학술논문 발표대회
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• pp.106-107
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• 2016

Construction waste is recycled and used for the efficient and eco-friendly disposal of construction waste increasing due to reconstruction and redevelopment project and so on. There is recycled aggregate as a typical case. And this recycled aggregate shows strong alkalinity due to calcium hydroxide, and causes many environmental problems. Therefore, this is a study on reduction in the strong alkalinity of recycled aggregate by using phosphate of ammonium in order to reduce the pH of recycled aggregate. Besides, a possibility that a pH reducing agent of recycled aggregate could be applied to a site was evaluated. As a result, it was possible to verify that pH decreased as the percentage of pH reducing agent increased. It is thought that the pH reducing agent can be applied to a site by methods such as immersion and spray using the pH reducing agent in the process of producing recycled aggregates.

• 한국물환경학회지
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• 제32권6호
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• pp.546-551
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• 2016

In this study, capping with recycled aggregate and natural zeolite in marine sediment was performed to investigate its inhibitory effect on pollutants released from sediment to seawater. An experiment was performed by capping with amendments for 60 days, and concentrations of organic matter (COD), nitrate, phosphate and metallic elements (Ni, Zn, Cu, Pb, Cd, As, and Cr) were measured. Two capping materials effectively suppressed pollutant release. Recycled aggregate showed better effectiveness for organic pollutant, nitrate and phosphate release. Meanwhile, natural zeolite was effective for metallic elements. As a result, recycled aggregate and natural zeolite can be considered as cost-effective/inexpensive capping material candidates. Also, the capping material can be selected according to the target pollutant.

• Restorative Dentistry and Endodontics
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• 제37권4호
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• pp.188-193
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• 2012

Mineral trioxide aggregate (MTA) was developed in early 1990s and has been successfully used for root perforation repair, root end filling, and one-visit apexification. MTA is composed mainly of tricalcium silicate and dicalcium silicate. When MTA is hydrated, calcium silicate hydrate (CSH) and calcium hydroxide is formed. Formed calcium hydroxide interacts with the phosphate ion in body fluid and form amorphous calcium phosphate (ACP) which finally transforms into calcium deficient hydroxyapatite (CDHA). These mineral precipitate were reported to form the MTA-dentin interfacial layer which enhances the sealing ability of MTA. Clinically, the use of zinc oxide euginol (ZOE) based materials may retard the setting of MTA. Also, the use of acids or contact with excessive blood should be avoided before complete set of MTA, because these conditions could adversely affect the hydration reaction of MTA. Further studies on the chemical nature of MTA hydration reaction are needed.

• 한국건축시공학회지
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• 제17권1호
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• pp.23-30
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• 2017

순환골재가 복토 및 성토용으로 활용되는 경우 순환골재 표면의 미수화 시멘트로부터 발생하는 높은 pH의 침출수는 환경에 큰 영향을 주는 요소이다. 본 연구에서는 이러한 높은 pH의 침출수를 방지하기 위해 순환골재의 효율적인 알칼리 제거 방안에 대해 실험적으로 비교분석 하였다. 실험결과 순환골재의 높은 알칼리성을 감소시키기 위해서는 단순 야적 및 물을 이용한 씻기 방법보다는 비료를 사용한 처리방법이 가장 유리한 것으로 나타났다. 또한, 본 연구에서는 비료의 종류인 인산암모늄과 이인산암모늄을 활용하여 순환골재를 중화시켰고 그 결과 약 3주 만에 pH 8의 중성에 가까운 순환잔골재를 얻을 수 있었다. 본 연구를 통해 순환골재를 토공사용으로 사용할 때에 보다 환경에 안전한 지속가능한 재료로서 활용하는 데에 기여할 것으로 예상한다.

• 한국건설순환자원학회논문집
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• 제3권4호
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• pp.366-373
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• 2015

재건축 재개발 사업 등으로 인하여 증가하는 건설폐기물을 효율적이고 친환경적으로 처리하기 위하여 건설폐기물을 재활용하여 사용하고 있다. 대표적으로 순환골재가 있으며, 이는 수산화칼슘에 의하여 높은 강알칼리성을 나타내며 많은 환경문제를 발생시키고 있다. 따라서 본 연구는 순환골재의 pH를 저감하기 위해 인산나트륨계암모늄염을 사용하여 순환골재의 강알칼리성을 감소시키기 위한 연구이다. 또한, 순환골재 pH 저감제의 현장적용 가능성을 평가하였다. 그 결과 pH 저감제 비율이 증가할수록 pH가 감소하는 것을 확인할 수 있었으며 순환골재 생산과정 중 pH 저감제를 이용한 침지, 분사 등의 방법으로 현장적용이 가능할 것으로 판단된다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1998년도 가을 학술발표대회 논문집(III)
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• pp.912-915
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• 1998

As a fundamental study on the development of porous concrete for planting, this study is designed to present the properties of porous concrete by varying the kinds of cement, paste to aggregate ratio and dosage of AE admixture. As the results of experiment, the void volumes show 30~33%, 25~ 28% and 17~22% respectively, with paste to aggregate ratio of 20%, 30% and 40%. And unit weight is 1700~1900kg/㎥ while compressive strengths 40~60, 8 0~100 and 120~150kg/$\textrm{cm}^2$. pH of concrete shows a sufficient value at which the plant could grow, when the concrete is permeated in Ammonium Phosphate Dibasic for more than 1 hour. In brief, it shows a possibility of development of porous concrete if the concrete is permeated with permeating in Ammonium Phosphate Dibasic for more than 1 hour when the blast furnace slag cement is used.

• KSBB Journal
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• 제5권4호
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• pp.347-353
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• 1990

The effects of nutrients and cell aggregate size on the cell growth of D. carota and the biosynthesi of carotenoid were investigated. Highest carotenoid content was obtained with sucrose as a carbon source and the equal ratio of ammonium to nitrate. High phosphate concentration stimulated the carotenoid biosynthesis in D. corota. 2,4-D inhibited the cell growth but stimulated the specific carotenoid content at high concentration. By modifying the medium composition based on these findings, three times higher specific carotenoid content and 2.5 times higher total carotenoid content were obtained as compared with the results obtained with basic MS media. Biosynthesis of carotenoid was found to be affected by cell aggregate size; high carotenoid production was obtained from the large aggregated cells resulted from high sucrose concentration.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2017년도 추계 학술논문 발표대회
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• pp.105-106
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• 2017

Previous studies have confirmed the performance of pH reduction agents using liquid sodium phosphate based ammonium chloride as a pH reduction agent. In this study, the pH reduction performance considering economical and applicability as a practical stage and the property change analysis for the identification of the reaction mechanism of the pH reduction agent were carried out. As a result, the pH reduction performance at a low rate of the pH reducing agent was confirmed. The specific gravity of CaO decreased significantly after XRF analysis. It is also believed that this reduces the amount of Ca(OH)₂ produced and contributes to pH reduction.

• 유기물자원화
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• 제26권1호
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• pp.29-37
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• 2018

본 연구에서는 하수슬러지 소각재에서 인을 회수하기 위한 최적 추출 조건을 조사하였다. 이를 위해 순환골재 잔재물 내에 존재하는 칼슘 성분을 이용하여 Ca-P 형태로 최적의 인 회수 조건을 결정하기 위한 실험을 진행하였다. 하수슬러지 소각재의 인 함량은 5 %로 확인되었다. $H_2SO_4$을 추출액으로 사용하였을 때, 1 N $H_2SO_4$의 농도와 L/S비 10, 그리고 추출시간 30분이 최적의 추출조건으로 조사되었다. 최적의 추출 조건을 이용하여 인을 추출한 다음 양이온교환수지 1 ~ 20 g 범위를 사용하여 인과 함께 용출된 중금속을 제거하였는데, 양이온교환수지 20 g에서 Fe 71.3 %, Cu 82.4 %, Zn 79.9 %, Cr 15 %가 제거되었다. 그 후 소각재 인 추출액과 순환골재 잔재물에서 얻은 칼슘 추출액의 혼합비율을 1:1, 1:5, 1:10으로 변화를 주었다. 1:5 혼합액에 5 N NaOH를 주입하여 pH를 2, 4, 8, 12로 조절한 후 인을 Ca-P 형태의 침전물로 회수하는 실험을 진행하였는데, 인이 Ca-P 형태로 침전되는 최적 pH는 8로 도출되었다. 순환골재 잔재물을 사용하였을 경우, 회수되는 침전물의 무게는 증가하였지만, 폐수 발생량이 증가하는 문제가 발생하였다. 따라서 순환골재 잔재물을 이용하는 것은 경제성이 낮다고 판단되었다.