• Korean Journal of Environmental Agriculture
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• v.27 no.4
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• pp.321-327
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• 2008

Soil conditioner, such as $CaSO_4{\cdot}2H_2O$ (gypsum), popped rice hulls (PRH), and PRH with zeolite, were treated to the silt loam of Mangyeong in Saemangeum tideland reclaimed as 1550 (G1), 3100 (G2) and 6200 (G3) of gypsum kg/10 a, 1000(H1), 2000(H2), and 3000 (H3) of PRH kg/10 a, and 200 (HZ1), 400 (HZ2), 800 (HZ3) of zeolite kg/10 a added to 1500 PRH kg/10 a, respectively, each year until 2006 from 2004 for soil aggregation. Under these conditions with growing bermuda grass (Cynodon dactylon) it was analyzed cations in soil, such as $K^+$, $Na^+$, $Mg^{2+}$, and $Ca^{2+}$, at 60, 90, and 120 days after treatment (DAT) to research how soil conditioners influenced to change those contents in soils, respectively. The change of cations in soil was almost the same things as fine sandy loam that gypsum treated decreased remarkably contents of $K^+$, $Na^+$, $Mg^{2+}$ in soil. The change of $K^+$ content in soil by continuous using soil conditioners was gradually decreased in the order of 2004>2005>2006, regardless of the sorts and levels of soil treated conditioners, and $K^+$ content was high in the order of gypsum$Na^+$ content was high in the order of gypsum$Mg^{2+}$ content in soil was increased in the order of gypsum$Ca^{2+}$ content in soil was remarkably increased with continuous treatment of gypsum, and its level was in the order of 2004<2005<2006.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.03a
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• pp.628-635
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• 2008

A series of cone penetration tests in large calibration chamber were performed to investigate the effect of cementation level, relative density and vertical confining stress on cone resistance. From the experimental results, it was observed that the cone resistance is increased with increasing gypsum content, relative density, and confining stress. The increasing ratio on cone resistance of cemented sand compared with that of uncemented sand, that is IR($q_c$), was increased with increasing gypsum content and relative density, whereas it was decreased as the vertical confining stress increases. It was also observed that the cementation of granular soil influences the behavior of ground at low level of confining stress and its effect is diminished with depth.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2002.10a
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• pp.145-148
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• 2002

This study is performed to properties of low heat concrete using blast furnace slag powder and gypsum. The test result shows that the air content is in the range of $4.1%{\sim}5.1%$, the unit weight is in the range of $2,306kg/m^3{\sim}2,334kg/m^3$. The compressive strength of concrete mixed blast furnace slag(BFS) low than ordinary portland cement(OPC) at the curing age of 7days, but it is high or same at the curing age of 28days. And the natural gypsum shows superior compressive strength than the chemical gypsum.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2009.05b
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• pp.77-80
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• 2009

The purpose of the study was to examine engineering characteristics due to fine particle cement and gypsum contents to improve early strength of concrete substituted blast furnace slag powder. The results were as follows. Above all, For fluidity, generally all mixtures had lower fluidity than Plain mixture and was not satisfied target scope, but for mixture substituted the gypsum showed a little increasing trend. For air content, generally all mixtures compared to Plain mixture had decreasing tendency. However, all mixtures were satisfied target scope. For compressive strength, long-term strength was better than early strength according to ternary blast furnace slag contents was increased. For complex mixture was better than individual use of gypsum and fine particle cement.

• Resources Recycling
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• v.31 no.3
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• pp.53-60
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• 2022

The physical properties of chlorine-containing cement were analyzed to optimize the operational conditions when waste resources containing chlorine were used in the cement manufacturing process. Cement with clinker to gypsum weight ratios of 95:5 and 93:7 were manufactured. In addition, the iron modulus (IM) of clinker was set to 1.3, 1.5, and 1.7 to evaluate the burnability and physical properties of clinker. With constant chlorine content, increasing gypsum content resulted in a decrease in the 3 day-compressive strength, whereas the 28 day-compressive strength increased. In addition, flow and setting time also increased with increasing gypsum content. As the IM decreased, burnability was improved, free-CaO content decreased, alite and ferrite content increased, and compressive strength increased In particular, the compressive strength of IM 1.3 was approximately 14% greater than that of IM 1.7.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.2C
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• pp.51-58
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• 2009

In this study, the small strain shear moduli ($G_{max}$) of uncemented and gypsum-cemented sands are evaluated by performing a series of bender element tests on the specimens reconstituted in the calibration chamber. It is observed from the experimental results that $G_{max}$ of crushed-sands is about 35~50% smaller than that of natural sands. The increase in gypsum content is observed to result in an exponential increase of $G_{max}$ value. It is also shown that the relative density has more significant effect on $G_{max}$ of cemented sand, whereas the vertical effective stress has more significant influence on $G_{max}$ of uncemented one. A prediction equation for cemented sand is expressed as a function of gypsum content as well as void ratio and vertical effective stress.

• Proceedings of the Korea Concrete Institute Conference
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• 1999.10a
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• pp.81-84
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• 1999

In this study, the influence of specific surface area of cement, substitution ratio of gypsum anhydrite on the physical properties of concrete were investigated by measurements of slump, air content and compressive strength. The results showed that reducing the specific surface area of cement under 3200$\textrm{cm}^2$/g and using 20% of gypsum anhydrite were desirable to prevent the decrease in workability and strength of concrete in summer season.

• Journal of the Korean Ceramic Society
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• v.44 no.9
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• pp.477-482
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• 2007

The effect of the mixing ratio of compounds in a slag-OPC-Gypsum system on the physical properties of Slag cement is investigated in this study. $Na_2SO_4$ was used as an alkali activator. Blast furnace slag cement was prepared from a mixture of blast furnace slag, ordinary Portland cement and anhydride gypsum. The fluidity and the compressive strength according to the ratio of each mixture were analyzed in statistical analyses in order to discover the parameters influencing the fluidity and compressive strength. The results showed that the hydration of blast furnace slag took place with the addition of $Na_2SO_4$ and that column-crystalline ettringite was created as the main hydration product of the blast furnace slag. In addition, it was found that the compressive strength of blast furnace slag cement tends to increase when the ordinary Portland cement content is higher up to three days. However, it is known that the compressive strength tends to increase as the blast furnace slag content becomes higher with increases in the level of OPC after 28 days. As a result of this analysis, it is believed that the ordinary Portland cement content influences the initial compressive strength of blast furnace slag cement, and that in later days this is highly influenced by the slag content.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.05a
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• pp.955-958
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• 2006

The purpose of this study is to find ways of recycling a great amount of gypsum as by-product from the manufacture of phosphate fertilizer. For the purpose, this researcher investigated physical properties of light weight Porous material using waste gypsum and a foaming agent, Sodium n-dodecyl Sulfate to utilize it as a interior material of construction. To determine such properties, the study examined pore size distribution and pore rate in accordance with contents of Sodium n-dodecyl Sulfate added. Then expanded vermiculite as light-weight aggregate was also added, when pore size distribution, pore rate and sound absorption rate were surveyed and measured.

• The Journal of Natural Sciences
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• v.7
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• pp.103-114
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• 1995

These experiments were conducted for decrease of injury by continuous cropping in the peanut fields of Chonbuk Wangkungarea. The continuous cropping field for four years was used in this experiment. Italian ryegrass and rye were cultivated andlime materials were distributed for improvement of soil fertility. The results were as follows; 1. Forage crops were cultivatedand lime materials were distributed on the continuous cropping field of peanut. The organic matter content of the expermentalplot cultivating Italian ryegrass was only 1.25%. The organic matter content of soil cultivated Italian ryegrass after distributedmagnesium lime was 1.37% and that of soil cultivated Italian ryegrass after distributed gypsum was 1.30%. It was highcontent comparing to that of soil distributed lime materials only. The organic matter content of soil cultivated rye after distributed gypsum was 1.77%. 2. The phosphate content of soil cutivated Italian ryegrass was 332ppm. The phosphate content ofsoil cultivated Italian ryegrass after distributed magnesium lime was 34Oppm and that of soil cultivated Italian ryegrass afterdistributed gypsum was 31 2ppm. The phosphate content of soil cultivated rye only was 386ppm. The phosphate content ofsoil cultivated rye after distributed gypsum was 41 8ppm. This phosphate content was lower than that of soil distributed limematerials only. 3. The phytotoxin content of soil cultivated Italian ryegrass after distributed magnesium lime was decreased to17.7% and that of soil cultivated Italian ryegrass after distributed gypsum was decreased to 25.3%. The phytotoxin content ofsoil cultivated rye after distributed magnesium lime was decreased to 12.0% and that of soil cultivated rye after distributedgypsum was decreased to 12.8% comparing to the phytotoxin content of soil distributed lime materials only. Italian ryegrasswas effective to decrease phytotoxin among the forage crops and gypsum was effective among the lime materials. 4. Abacterial wilt and a late spot of peanut which were known as, main reason of continuous cropping failure were surveyed.lnccidence of a bacterial wilt was 3.4% in the plot cultivated Italian ryegrass only and that was 2.9% in the plot cultivated ryeonly. lnccidence of a bacterial wilt was 2.5% in the plot cultivated Italian ryegrass after distributed magnesium lime and thatwas 2.3% in the plot cultivated rye after distributed gypsum. Inccidence plot cultivated forage crops was lower than that of plotdistributed lime materials. 5. Inccidence of a late spot was high in the plot cultivated forage crops ony, but it was low in the plotcultivated forage crops after distributed lime materials comparing to that of the control plot. 6. The growth and yield of peanutwere bad in the plot cultivated forage crops only comparing to the control plot distributed lime materials only. These resultswere same in the plot cultivated rye after distributed lime materials, but the growth and yield were grown up in the plotcultured Italian ryegrass after distributed lime materials.