• Journal of the Korean Society of Safety
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• v.10 no.3
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• pp.62-67
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• 1995

The combustion characteristics of cellulose Insulation treated with several metal complexes such as Aluminium hydroxide, Cupric sulfate pentahydrate, Magnesium sulfate heptahydrate, Manganese chloride tetrahydrate and Tnisodium phosphate dodecahydrate are studied to evaluate the effectiveness as a potential flame retardant for cellulosic materials. In this study, we found that LOI values of cellulosic materials treated with the metal complexes are generally increased with the increase of their content. At high concentration, CS(24% ) and SP(24% ) show high LOI values, suggesting resistance to flame spread, The materials examined in this study were found to be relatively more resistance to smouldering and flaming combustion in comparision with untreated cellulosic material. The flammability behavior of the materials exhibits combustion process as follows : LOI$\rightarrow$smouldering region$\rightarrow$smouldering-flaming spread region$\rightarrow$flame spread region.

• Proceedings of the Korea Concrete Institute Conference
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• 2000.10a
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• pp.399-402
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• 2000

When concrete structures are built in marine environment, they may be deteriorated and have the poor durability and quality caused by steel corrosion or by chemical attack of magnesium or sulfate ions. Especially, Mg ions contained in seawater make concrete surface weaken by chemical reaction with $Ca(OH)_2$ In this study, a concrete structure built in 1947 was investigated to estimate the factors, especially chemical attack, which can cause concrete to deteriorate. Furthermore, the instrumental analysis methods such as XRD and ESEM were performed to find the reactants in concrete under marine environment.

• YAKHAK HOEJI
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• v.36 no.6
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• pp.538-547
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• 1992

Optimal synthetic condition of barium sulfate were investigated from the viewpoint of yield and bulkiness according to a randomized complete block design proposed by G.E.P. Box and K.B. Wilson. Barium chloride and magnesium sulfate were utilized as reactants in order to prepare barium sulfate in this study. It was found that optimum temperature range of reactant solutions was $60{\sim}100^{\circ}C$ and the optimum concentration range of the reactant solutions was $10{\sim}17.3%$ and $10{\sim}20%$ respectively, on the viewpoint of yield and bulkiness. The optimum mole ratio of $BaCI_2$ to $BaSO_4$ was in the range of $1.50{\sim}2.0$ and the optimum mole ratio of $BaCI_2$ to $BaSO_4$ was in the range of $1.50{\sim}2.0$ and the optimum reacting time range was $15{\sim}20$ minutes. The optimum drying temperature range was $110{\sim}130^{\circ}C$ from the viewpoint of yield, but it was $90{\sim}110^{\circ}C$ on the basis of bulkiness. Apparent viscosity of barium sulfate suspensions dispersed in various concentrations of Na. CMC was measured by using Brookfield synchrolectric viscometer model LVT, the relative equation, log ${\eta}_{sp}=A+B.{\phi}$ was examined and the equation was found to agree fairly well. 1 w/v% Na. CMC aqueous solution and 0.1 volume fraction of $BaSO_4$ powder were optimum in the preparation of $BaSO_4$ suspension showing highest viscosity at infinite shearing.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.421-424
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• 2008

The purpose of this experimental research is to investigate the influence of cement types on the resistance to acid and sulfate. For this purpose, concrete specimens with three types of cement such as ordinary portland cement(OPC), binary blended cement(BBC), and ternary blended cement(TBC) were made for water-binder(W/B) ratios of 32% and 43%, and then according to JSTM C 7401, the appearance change and ratio of mass change of them were estimated through the immersion tests by 5% sulfuric acid, 10% sodium sulfate, and 10% magnesium sulfate solution, respectively. It was observed from the test result that the resistance against acid and sulfate increased with decreasing W/B ratio and those of BBC and TBC concretes were better than the case of OPC concrete from immersion tests of 91 days.

• Journal of the Korean Society of Food Science and Nutrition
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• v.16 no.4
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• pp.251-261
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• 1987

This study was attempted to increase the production of L-Threonine by Brevibacterium Flavum ATCC 14067, To select the strain which produce the highest threonine, mutants ere induced by N-methyl-N'-nitro-N-nitrosoguanidine treatment. The composition of media and cultural condition for its overproduction of threonine were also studied. In a threonine producer, strain B-13(Met-) was the strain producing the highest amount of threonige among methionine, lysine and isoleucine auxotrophs. The following results were obtained. 1. The wild strain and B-13(Met-) produced threonine 1.4mg/ml and 4.86mg/ml , respectively. 2. The optimum composition of medium for producing threonine by Brevibacterium Flavum B-13 was glucose 10%, ammonium sulfate 4%, potassium phosphate monobasic 0.2%, magnesium sulfate 0.05%, biotin $200{\mu}l$, thiamine $300{\mu}l$. Addition of nicotinic acid also led to increase L-threonine production. 3. In addition of organic nutrients to the fermentation medium, peptone n'ere effective and addition of methionine $100{\mu}g/ml$ produced the highest amount of L-Threonine. Aspartic acid and homoserine were also effective when these amino acid were added to the fermentstion medium. 4. Cultural conditon on threonine production by B-16 were investigated. The optimum pH was 7.0-8.0. The highest amount of threnine was produced after 4 days of cultural period.

• Food Science and Preservation
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• v.30 no.1
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• pp.132-145
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• 2023

In this study, culture conditions were optimized to confirm the feasibility of Acetobacter pasteurianus as a starter for fermentation vinegar. Acetobacter pasteurianus strain can be used as a food ingredient. The optimal temperature and pH conditions of the selected Acetobacter pasteurianus SRCM101388 were 28℃ and pH 6.00, respectively. The response surface methodology (RSM) was used to optimize the composition of the medium, and Plackett-Burman design (PBD) was used to obtain the effective selection of culture medium, resulting in that glucose, sucrose, and yeast extract had the highest effect on increasing biomass. The optimal concentration, which was performed by central composite design (CCD), were determined to be 10.73 g/L of glucose, 3.98 g/L of sucrose, and 18.73 g/L of yeast extract, respectively. The optimal concentrations of trace elements for the production of biomass were found to be 1 g/L of ammonium sulfate, 0.5 g/L of magnesium sulfate, 2 g/L of sodium phosphate monobasic, 2 g/L of sodium phosphate dibasic, and the final optimized medium was pH 6.10. When incubated in a 5 L jar fermenter, the SRCM101388 strain showed a faster-dissolved oxygen (DO) reduction at a lower agitation rate (rpm), and it was able to grow even at reduced DO level when aeration was maintained. The amount of final biomass produced was 2.53±0.12×10⁹ CFU/mL (9.40±0.02 log CFU/mL) when incubated for 18 hours at 150 rpm, 0.5 vvm, pH 6.0, and 28℃.

• Journal of Life Science
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• v.17 no.11
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• pp.1539-1546
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• 2007

We have investigated whether the supplement of magnesium to cold blood cardioplegia improves myocardial protection. Sixty patients scheduled for elective valvular heart surgery were randomly assigned to a control group (n=30) which received conventional cold blood cardioplegia and an Mg group (n=30) which received cold blood cardioplegia supplemented with 2 g of magnesium sulfate. Electrolytes levels including $Mg^{++}$, hematological and biochemical variables, cytokines, myocardial marker levels, and postoperative outcomes were compared between two groups before, during or idler operation. $Mg^{++}\;and\;Ca^{++}$ levels in the Mg group were higher than those of the control group after surgery. The total WBC counts, CK-MB, troponin-I and Interleukin-6 levels in the Mg group were lower than those of the control group after surgery. Postoperative incidence of atrial fibrillation was lower in the Mg group compared with the control group. These results showed that $Mg^{++}$ attenuated inflammatory reaction, myocardial damage, and hypomagnesemia during valvular surgery and reduced postoperative arrhythmia incidence without side effects.

• Advances in concrete construction
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• v.6 no.4
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• pp.345-362
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• 2018

In this paper, mechanical and short-term durability properties of fly ash and slag based geopolymer concretes (FAGPC-SGPC) were investigated. The alkaline solution was prepared with a mixture of sodium silicate solution ($Na_2SiO_3$) and sodium hydroxide solution (NaOH) for geopolymer concretes. Ordinary Portland Cement (OPC) concrete was also produced for comparison. Main objective of the study was to examine the usability of geopolymer concretes instead of the ordinary Portland cement concrete for structural use. In addition to this, this study was aimed to make a contribution to standardization process of the geopolymer concretes in the construction industry. For this purpose; SGPC, FAGPC and OPC specimens were exposed to sulfuric acid ($H_2SO_4$), magnesium sulfate ($MgSO_4$) and sea water (NaCl) solutions with concentrations of 5%, 5% and 3.5%, respectively. Visual inspection and weight change of the specimens were evaluated in terms of durability aspects. For the mechanical aspects; compression, splitting tensile and flexural strength tests were conducted before and after the chemical attacks to investigate the residual mechanical strengths of geopolymer concretes under chemical attacks. Results indicated that SGPC (100% slag) is stronger and durable than the FAGPC due to more stable and strong cross-linked alumina-silicate polymer structure. In addition, FAGPC specimens (100% fly ash) showed better durability resistance than the OPC specimens. However, FAGPC specimens (100% fly ash) demonstrated lower mechanical performance as compared to OPC specimens due to low reactivity of fly ash particles, low amount of calcium and more porous structure. Among the chemical environments, sulfuric acid ($H_2SO_4$) was most dangerous environment for all concrete types.

• Biomedical Science Letters
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• v.2 no.2
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• pp.283-288
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• 1996

A total of 31 human diphyllobothriasis cases have been reported in Korea. Authors experienced two more human cases of Diphyllobothrium latum infection, especially due to eating raw freshwater trout. Two cases were husband and wife in a famil residing in Chunchon city, Kangwon-do, who raw fish in October 1994. A 43-year old male(husband) was 69kg in body weight and healthy. A worm (6.65m in length; 8-l3mm in width) was expelled from him after, anthelmintic treatment. The second case(wife) was a 39-year old female who weighted 56kg. She complained about gastrointestinal trouble and abdominal discomfort. A worm (5.50m in length; 9-l3mm in width) was Obtained her after anthelmintic treatment. No scolex was collected from the two worms. Two patients were administrated with praziquantel(15mg/kg of body weight) and 15gm of magnesium sulfate as a purgative. Two worms identified as D. latum, .based on the following biological characters: extermal morphologies, coiling of uterus, the number of uterine loops, position of genital opening, morphologies of cirrus and cirrus sac and seminal vesicle on the histological sections, positions of vagina and uterine pore, distribution patterns of vitellaria, and microscopical and SEM morphologies of the egg.

• Journal of Powder Materials
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• v.27 no.5
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• pp.401-405
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• 2020

Magnesium hydroxide sulfate hydrate (MHSH) whiskers were synthesized via a hydrothermal reaction by using MgO as the reactant as well as the acid solution. The effects of the H₂SO₄ amount and reaction time at the same temperature were studied. In general, MHSH whiskers were prepared using MgSO₄ in aqueous ammonia. In this work, to reduce the formation of impurities and increase the purity of MHSH, we employed a synthesis technique that did not require the addition of a basic solution. Furthermore, the pH value, which was controlled by the H₂SO₄ amount, acted as an important factor for the formation of high-purity MHSH. MgO was used as the raw material because it easily reacts in water and forms Mg⁺ and MgOH⁺ ions that bind with SO₄^2- ions to produce MHSH. Their morphologies and structures were determined using X-ray diffraction (XRD) and scanning electron microscopy (SEM).