• Journal of environmental and Sanitary engineering
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• v.17 no.4
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• pp.10-18
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• 2002

The changes of conventional clarification processe and an increase in treatment cost are required to meet increasingly stringent regulations related to the treated water quality. Although many enhanced coagulations have introduced to improve organic matter removal, the results to remove color, nitrogen and phosphorus as well as organic material have not been very efficient yet. In this context as new flocculation using calcium hydroxide and magnesum sulfate was carried out. The removal of waste matters such as SS, organic matter, COD, nitrogen and phosphorus contained in stock wastewater was carried out by using the combination of calcium hydroxide and magnesium sulfate. The flocculation was investigated as a function of coagulant dose, pH, mixing time, settling time and coagulant addition modes such as the sequential addition of the two coagulants and the simultaneous addition of them. The flocculation by the combination of calcium hydroxide and magnesium sulfate was compared with that by aluminum sulfate. The mechanism of flocculation was investigated as well. About 60% of COD in stock watewater was removed by flocculation with combination of calcium hydroxide and magnesium sulfate.

• Journal of the Korea Institute of Building Construction
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• v.9 no.3
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• pp.109-116
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• 2009

The magnesium sulfate solution digestion test carried out for resistance of concrete containing waste glass powder on magnesium sulfate attack. Moreover, it yielded S.D.F index was used for the criteria of quantitative assessment to the resistance of magnesium sulfate for the purpose of evaluation of chemical deterioration on concrete. Furthermore, to evaluate for micro-cracks within concrete and external corrosion, the weight variation of specimens and the dynamic elasticity were compared and analyzed and also the applicability was examined using the analysis of product of hydration through out observing external deformation and micro-structural deformation.

• Steel and Composite Structures
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• v.29 no.2
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• pp.201-218
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• 2018

In this study, the effects of magnesium sulfate on the mechanical performance and the durability of confined and unconfined geopolymer concrete (GPC) specimens were investigated. The carbon and basalt fiber reinforced polymer (FRP) fabrics with 1-layer and 3-layers were used to evaluate the performances of the specimens under static and cyclic loading in the ambient and magnesium sulfate environments. In addition, the use of FRP materials as a rehabilitation technique was also studied. For the geopolymerization process of GPC specimens, the alkaline activator has selected a mixture of sodium silicate solution ($Na_2SiO_3$) and sodium hydroxide solution (NaOH) with a ratio ($Na_2SiO_3/NaOH$) of 2.5. In addition to GPC specimens, an ordinary concrete (NC) specimens were also produced as a reference specimens and some of the GPC and NC specimens were immersed in 5% magnesium sulfate solutions. The mechanical performance and the durability of the specimens were evaluated by visual appearance, weight change, static and cyclic loading, and failure modes of the specimens under magnesium sulfate and ambient environments. In addition, the microscopic changes of the specimens due to sulfate attack were also assessed by scanning electron microscopy (SEM) to understand the macroscale behavior of the specimens. Results indicated that geopolymer specimens produced with nano-silica and fly ash showed superior performance than the NC specimens in the sulfate environment. In addition, confined specimens with FRP fabrics significantly improved the compressive strength, ductility and durability resistance of the specimens and the improvement was found higher with the increased number of FRP layers. Specimens wrapped with carbon FRP fabrics showed better mechanical performance and durability properties than the specimens wrapped with basalt FRP fabrics. Both FRP materials can be used as a rehabilitation material in the sulfate environment.

• Korean Journal of Poultry Science
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• v.37 no.2
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• pp.131-137
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• 2010

The present study has been performed to suggest a method to decrease the adverse effects of transportation on chicken meat quality. The groups were prepared as follows; Control group and three groups of treatments (sodium phosphate, sodium bicarbonate and magnesium sulfate). The chicken fed magnesium sulfate showed higher chicken meat quality compared to control and other treatment groups. Also, minor and severe PSE incidence of chicken breast was found at 88% in sodium phosphate group, 24% in sodium bicarbonate group and 56% in magnesium sulfate group. Control group showed 92% higher minor and severe PSE incidence of chicken breast compared to other groups. In control group, the external bruise of chicken showed 32% but 22, 24 and 44% in other treatment groups, respectively. Lightness ($L^*$) of chicken containing sodium phosphate treatment, sodium bicarbonate treatment and magnesium sulfate were 67.05, 66.27 and 65.89, while Lightness ($L^*$) of chicken containing control group was decreased of 67.88. In conclusion, dietary buffer material (sodium phosphate, sodium bicarbonate, magnesium sulfate) under heat stress decreased adverse effects including death, wound or abnormality of chickens.

• Journal of environmental and Sanitary engineering
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• v.17 no.3
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• pp.89-98
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• 2002

The changes of conventional clarification process and an increase in treatment cost are required to meet increasingly stringent regulations related to the treated water quality. Although many enhanced coagulations have introduced to improve organic matter removal, the results to remove color, nitrogen and phosphorus as well as organic material have not been very efficient yet. The removal of waste matters such as SS, organic matter, color and turbidity contained in dyeing wastewater was carried out by using the combination of calcium hydroxide and magnesium sulfate. The flocculation was investigated as a function of coagulant dose, pH, mixing time, settling time and coagulant addition modes such as the sequential addition of the two coagulants and the simultaneous addition of them. The flocculation by the combination of calcium hydroxide and magnesium sulfate was compared with that by aluminum sulfate. The mechanism of flocculation was investigated as well. About 84% of color in dyeing watewater was removed by flocculation with combination of calcium hydroxide and magnesium sulfate.

• Computers and Concrete
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• v.29 no.5
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• pp.335-346
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• 2022

Geopolymers are an important alternative material supporting recycling, sustainability, and waste management. Durability properties are among the most critical parameters to be investigated; in this study, the durability of manufactured geopolymer samples under the attack of 10% magnesium sulfate and 10% sodium sulfate solution was investigated. 180 cycles of freezing and thawing were also tested. The experimentally obtained results investigate the durability of geopolymer mortar prepared with fly ash (class F) and alkali activator. Three different quarry dust wastes replaced the river sand aggregate: limestone, marble, and basalt powder as fine filler aggregate in three different replacement ratios of 25%, 50%, and 75% to produce ten series of geopolymer composites. The geopolymer samples' visual appearance, weight changes, UPV, and strength properties were studied for up to 12 months at different time intervals of exposure to sulfate solutions to investigate sulfate resistance. In addition, Scanning Electron Microscopy (SEM), EDS, and XRD were used to study the microstructure of the samples. It was beneficial to include quarry waste as a filler aggregate in durability and mechanical properties. The compact matrix was demonstrated by microstructural analysis of the manufactured specimens. The geopolymer mortars immersed in sodium sulfate showed less strength reduction and deterioration than magnesium sulfate, indicating that magnesium sulfate is more aggressive than sodium sulfate. Therefore, it is concluded that using waste dust interrogation with partial replacement of river sand with fly ash-based geopolymers has satisfactory results in terms of durability properties of freeze-thaw and sulfate resistance.

• The Journal of Korean Academy of Prosthodontics
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• v.28 no.1
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• pp.137-163
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• 1990

The properties of a investment material can be described by the consistency at the slurry state, the setting time, the compressive strength and the thermal expansion during the casting. In this study the effect of the production parameters which are included the ratio of quartz and cristobalite, the content of binder, the water powder ratio and the content and concentration of additives on the Properties of the gypsum-bonded investments has been investigated with help of the consistency test, the vicat needle test, the compressive strength test, the thermal expansion test, x-ray diffraction and DTA thermal differential test. The experimental results showed that the constitution of a investment with W/P ratio of 0.34, 30% of gypsum, 0.8% aluminium sulfate, 2% magnesium sulfate, 0.6% sodium phosphate was adapted for the properties of the KDA Spec. No. 13 type I investment. The important experimental results are summarized as follows. 1. The consistency of the investment decreased with increasing amount of aluminium sulfate and decreasing amount of sodium phosphate. An addition of magnesium sulfate up to 2% an increase of the consistency was shown. But 3% magnesium sulfate in investment showed a decrease of the consistency. The consistency did not vary significantly with a variation of the content of gypsum and cristobalite and the W/P ratio. 2. Aluminium sulfate and the magnesium sulfate promoted the hardening and the aluminium phosphate delayed the hardening. The setting time increased with amount of gypsum. The effect of the matrix on the setting time was insignificant. With the W/P ratio of 0.34 the setting time was 14 min. 3. The compressive strength decreased with the amount of aluminium sulfate up to 0.25% and increased with the amount of aluminium sulfate greater than 3%. The compressive strength decreased as decreasing the amount of magnesium sulfate and gypsum and as increasing the W/P ratio. The effect of the refractory on the compressive strength was also not significant. With the W/P ratio of 0.34 the compressive strength was $34Kg/mm^2$. 4. The 1st thermal expansion was found at the temperature near and the steady state or the contraction stage was found at the temperature between $250^{\circ}C$ and $500^{\circ}C$. After this stage the 2nd thermal expansion took place at the temperature near $500^{\circ}C$. The amount of thermal expansion increased with decreasing the content of magnesium sulfate, aluminium sulfate and gypsum and the W/P ratio. And the amount of thermal expansion increased as the content of sodium phosphate and cristobalite. With the W/P ratio of 0.34 the amount of total expansion was 1.2%.

• Food Science and Preservation
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• v.18 no.5
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• pp.678-683
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• 2011

The effects of coagulant types (magnesium chloride, calcium chloride, calcium sulfate, glucono-${\delta}$-lactone) on yield, quality properties and storability of astringent persimmon powder added tofu were investigated. Yield, hardness, chewness, crispness, and overall acceptability of tofu coagulated by glucono-${\delta}$-lactone were higher than those coagulated by the others. L value, a value, pH, soaking-solution turbidity, and total aerobic bacteria of glucono-${\delta}$-lactone coagulated tofu were lower than those coagulated by the others. Calcium sulfate and calcium chloride coagulated tofu showed relatively high L and b values. Magnesium chloride coagulated tofu had higher sensory score for firmness, taste, overall acceptability than calcium chloride and calcium sulfate coagulated tofu, but there was no significant difference between magnesium chloride and glucono-${\delta}$-lactone. The results suggested that glucono-${\delta}$-lactone and magnesium chloride were found to be the suitable coagulants for processing of the persimmon powder added tofu.

• The Korean Journal of Pain
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• v.30 no.3
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• pp.207-213
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• 2017

Background: Surgeon satisfaction and patient analgesia during the procedure of laparoscopic surgery are important issues. The aim of this work was to study if an intrathecal (IT) Bupivacaine combined with Magnesium sulfate may or may not provide good surgeon satisfaction in addition to improvement of intraoperative and postoperative analgesia. Methods: Sixty female patients were enrolled in this prospective, randomized, double-blind controlled clinical trial study. All patients were operated for gynecological laparoscopic surgery under spinal anesthesia. Patients were divided into two groups (Bupivacaine and Magnesium). Group Bupivacaine (30 patients) received intrathecal Bupivacaine 0.5% only (15 mg), while 30 patients in group Magnesium received intrathecal Bupivacaine (15 mg) in addition to intrathecal Magnesium sulfate (50 mg). The sensory block level, the intensity of motor block, the surgeon satisfaction, the intraoperative visual analog scale (VAS) for pain assessment, the postoperative VAS, and side effects were recorded during the intraoperative period and within the first 24 hours after surgery in the post-anesthesia care unit. Results: Surgeon satisfaction, intraoperative shoulder pain, postoperative pain after 2 h, and perioperative analgesic consumption (ketorolac) were significant better in group Magnesium than in group Bupivacaine. (P < 0.05). The onset of motor and sensory blocks was significant longer in group Magnesium than the other one. The incidence of PONV, pruritus and urinary retention was insignificant statistically between both groups. Conclusions: Magnesium sulfate if used intrathecally as an adjuvant to Bupivacaine would provide a better surgeon satisfaction and would improve the analgesic effect of spinal anesthesia used for gynecological laparoscopic surgery.

• The Journal of Korean Academy of Prosthodontics
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• v.29 no.1
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• pp.139-165
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• 1991

The properties of a investment material can be described by the consistency at the slurry state, the setting time, the compressive strength and the thermal expansion during the casting. In this study the effect of the production parameters which are included the ratio of quartz and cristobalite, the content of binder, the water powder ratio and the content and concentration of additives on the properties of the gypsum-bonded investments has been investigated with help of the consistency test, the vicat needle test, the compressive strength test, the thermal expansion test, x-ray diffraction and DTA thermal differential test. The experimental results showed that the constitution of a investment with W/P ratio of 0.34, 30% of gypsum, 0.8% aluminium sulfate, 2% magnesium sulfate, 0.6% sodium phosphate was adapted for the properties of the KDA Spec. No. 13 type I investment. The important experimental results are summarized as follows. 1. The consistency of the investment decreased with increasing amount of aluminium sulfate and decreasing amount of sodium phosphate. An addition of magnesium sulfate up to 2% an increase of the consistency was shown. But 3% magnesium sulfate in investment showed a decrease of consistency. The consistency did not vary significantly with a variation of the content of gypsum and cristobalite and the W/P ratio. 2. Aluminium sulfata and the magnesium sulfate promoted the hardening and the aluminium phoshpate delayed the hardening. The setting time increased with amount of gypsum. The effect of the matrix on the setting time was insignificant. With the W/P ratio of 0.34 the setting time was 14 min. 3. The compressive strength decreased with the amount of aluminium sulfate up to 0.25% and increased with the amount of aluminium sulfate greater than 3%. The compressive strength decreased as decreasing the amount of magnesium sulfate and gypsum and as increasing the W/P ratio. The effect fo the refractory on the compressive strength was also not significant. With the W/P ratio of 0.34 the compressive strength was $34Kg/mm^2$. 4. The 1st thermal expansion was found at the temperature near $250^{\circ}C$ and the steady state or the contraction stage was found at the temperature between $250^{\circ}C$ and $500^{\circ}C$. After this stage the 2nd thermal expansion took place at the temperature near $500^{\circ}C$. The amount of thermal expansion increased with decreasing the content of magnesium sulfate, aluminium sulfate and gypsum and the W/P ratio. And the amount of thermal expansion increased as the content of sodium phosphate ad cristobalite. With the W/P ratio of 0.34 the amount of total expansion was 1.2%.