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MgCO<sub>3</sub>와 사문석을 사용한 마그네시아 시멘트의 특성평가
이종규,소정섭,추용식,송훈,박지선,Lee, Jong-Kyu,Soh, Jung-Sub,Chu, Yong-Sik,Song, Hun,Park, Ji-Sun 한국재료학회 2012 한국재료학회지 Vol.22 No.11
MgO based cement for the low-temperature calcination of magnesite required less energy and emitted less $CO_2$ than the manufacturing of Portland cements. Furthermore, adding reactive MgO to Portland-pozzolan cement can improve their performance and also increase their capacity to absorb atmospheric $CO_2$. In this study, the basic research for magnesia cement using $MgCO_3$ and magnesium silicate ore (serpentine) as starting materials was carried out. In order to increase the hydration activity, $MgCO_3$ and serpentinite were fired at a temperature higher than $600^{\circ}C$. In the case of $MgCO_3$ as starting material, hydration activity was highest at $700^{\circ}C$ firing temperature; this $MgCO_3$ was completely transformed to MgO after firing. After the hydration reaction with water, MgO was totally transformed to $Mg(OH)_2$ as hydration product. In the case of using only $MgCO_3$, compressive strength was 35 $kgf/cm^2$ after 28 days. The addition of silica fume and $Mg(OH)_2$ led to an enhancements of the compressive strength to 55 $kgf/cm^2$ and 50 $kgf/cm^2$, respectively. Serpentine led to an up to 20% increase in the compressive strength; however, addition of this material beyond 20% led to a decrease of the compressive strength. When we added $MgCl_2$, the compressive strength tends to increase.
C<sub>3</sub>A-CaSO<sub>4</sub>·2H<sub>2</sub>O 계의 수화반응에 미치는 석회석 미분말의 영향
이종규,추용식,송훈,Lee, Jong-Kyu,Chu, Yong-Sik,Song, Hun 한국세라믹학회 2011 한국세라믹학회지 Vol.48 No.6
In this work, effects of limestone powder on hydration of $C_3A-CaSO_4{\cdot}2H_2O$ system was discussed based on the XRD Quantitative analysis, and the possibility of Delayed Ettringite Formation was also discussed. The early hydration of $C_3A$ was delayed by addition of $CaCO_3$ powder. The delay effect was enhanced by increasing of $CaCO_3$ content and finer powder of $CaCO_3$ addition. After consumption of $CaSO_4{\cdot}2H_2O$, the reaction of $CaCO_3$ is started. Delayed Ettringite Formation would take place because monosulfoaluminate is not stable in presence of $CaCO_3$. In order to prevent the delayed ettringite formation in $C_3A-CaSO_4{\cdot}2H_2O-CaCO_3$ system, the reduction of monosulfoaluminate formation is important. Therefore, by increasing the amount of $CaCO_3$ addition and finer $CaCO_3$ powder addition, the delayed ettringite formation can be prevented.
이종규,추용식,송훈,Lee, Jong-Kyu,Chu, Yong-Sik,Song, Hun 한국재료학회 2011 한국재료학회지 Vol.21 No.12
One of the trace constituents included in cement clinker, chromium, has become prominent and highly noticed lately as a social issue both inside and outside of this country because it affects the human body negatively. The purpose of the present study was to investigate leaching properties of water-soluble hexavalent chromium by different manufacturing conditions of cement clinker. Raw materials were prepared to add different $SiO_2$, $Al_2O_3$ and $Fe_2O_3$ sources. After the raw materials, such as limestone, sand and clay, iron ore was pulverized and mixed, and the raw meal was burnt at $1450^{\circ}C$ in a furnace with an oxidizing atmosphere. Leaching of soluble hexavalent chromium showed a tendency to decrease with an increasing LSF and IM. However, leaching of soluble hexavalent chromium increased with an increasing S.M. Alkali contents of iron source minerals is closely related to the leaching properties of soluble hexavalent chromium. Green sludge has the highest content of alkali added; leaching of water-soluble hexavalent chromium was mostly high. In order to reduce the water-soluble hexavalent chromium in cement, reducing the alkali content in raw materials is important.
동위원소 ( 125I - Iothalmate ) 를 이용한 신사구체 여과율 측정의 임상적 유용성
이종규(Jong Kyu Lee),전희경(Hee Kyung Chun),김승준(Seung Jun Kim),이승헌(Seung Hun Lee),양철우(Chul Woo Yang),김용수(Yong Soo Kim),최의진(Euy Jin Choi),장윤식(Yoon Sik Chang),방병기(Byung Kee Bang),양우진(Woo Jin Yang),정수교(Soo Kyo 대한내과학회 1995 대한내과학회지 Vol.49 No.5
N/A Objectives: Creatinine clereance is a widely used method for measuring glomerular filtration rate in clinical field but has been accepted as inaccruate method because of inadequate urine sampling and method of measuring plasma creatinine. In contrast, on inulin clearance is the ideal method of measuring glomerular filtration rate but it is not used routinely because of difficulty of method. Recently, many reports of the glomerular filtration rate using isotopes showed accurate glomarular filtration rate compared to inulin clearance. Therefore, we performed this study at outpatient clinic basis to find out whether the glomerular filtration rate using isotope (125I-iothalmate) is well correlated with other parameters that are used in clinical field. Methods: We measured GFB using 125I-iothalmate(Ciot) and compared it to other methods (99mTc-DTPA(C-DTPA), creatinine clearance(Ccr), predicted creatinine clearance(PCcr)) Results: 1) Mean differences of GFR measured by Ciot showed no sighificant changes during study preiod. 2) Ciot was well correlated with PCcr(r=0.88), Ccr(r=0.83), 100/Scr(r=0.83) and C-DTPA(r=0.75). 3) C-DTPA was higher than Ciot, especially in cases with severely impaired reanl function. 4) In patients with normal renal function(Scr <1.3 mg/dl), Ccr was not higher than Ciot (88.9±26.4 vs 97.7±18.8 ml/min/1.73M(2), p=0,008), and in patients with impaired renal function, Ccr was higher than Ciot but its degree was lower than expected (42.3±21.5 vs 35.7±18.2 ml/min/1.73M(2), p=0.0004). Conclusion: These observations suggest that Ccr is underestimated because of inadequate urine collection and other laboratory errors, And the determination of glomerular filtration rate using 125I-iothalmate seems to be an adequate method.
정의종,이종규,정덕수,추용식,송훈,Jeong, Eui-Jong,Lee, Jong-Kyu,Cheong, Deock-Soo,Chu, Yong-Sik,Song, Hun 한국재료학회 2009 한국재료학회지 Vol.19 No.10
Active clays, Diatomite, bentonite and zeolite were used as porous materials for fabricating hygroscopic gypsum boards. Pohang active clay and Cheolwon diatomite showed excellent characteristics of moisture adsorption and desorption. These characteristics were caused by higher surface area and pore volume of porous materials. Moisture adsorption content of gypsum board with 10% active clay(P1) was 62.0 g/m$^2$, and moisture desorption content was 50.2 g/m$^2$. Moisture adsorption content of gypsum board with 10% diatomite(P) was 59.5 g/m$^2$, and moisture desorption content was 49.0 g/m$^2$. Moisture adsorption contents of gypsum boards with porous materials were higher than that moisture desorption contents of gypsum board without porous materials. Correlation coefficient between surface area and moisture adsorption content of gypsum boards was 0.98. Also, correlation coefficient between surface area and moisture desorption content of gypsum boards was 0.97. Moisture adsorption and desorption contents were influenced by surface area and pore volume of the gypsum boards, and surface area had a larger effect on moisture adsorption and desorption.