• YAKHAK HOEJI
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• v.40 no.1
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• pp.25-35
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• 1996

Magaldrate. an antiacid was synthesized by reacting magnesium oxide, aluminum sulfate, and dried aluminum hydroxide gel. The optimum synthesis conditions based on the yield of t he product were established by applying Box-Wilson experimental design. It was found that the optimum synthesis conditions of Magaldrate were as follows: Reaction temperature; 61~$85{\circ}C$, concentration of two reactants. Mgo and $Al(OH)_3$: 16~19.8%, molar concentration ratio of two reactants, [MgO]/[$Al(OH)_3$]; 4.2~5.0, temperature of washing water; 36~$41^{\circ}C$ and drying temperature of the product: 76~$80^{\circ}C$. Magaldrate was synthesized under the optimum synthesis conditions and identified by analyzing the chemical composition, and by differential scanning calorimetry and X-ray diffraction method. The Magaldrate sample synthesis under these conditions was used to prepare 15.6% Magaldrate original suspension which was utilized to make 13% Magaldrate suspension dispered in various concentrations of eight types of suspending agents. The acid-neutralizing capacity of 13% Magaldrate suspension dispersed in 0.25% suspending agents was examined by Rosset-Rice method. The maximum pH was reached within 1 minute in all suspension tested, and duration maintained between pH 3~5 was decreased in the order of Na alginate Na silicate(meta) Veegum HV pectin agar>Na>CMC>xanthan gum>bentonite. It was found that the hysteresis loop area was increased with temperature in the case of Riopan Plus and the addition of agar, whereas the area was decreased with temperature in the case of the addition of Na alginate and xanthan gum. 13% Magaldrate suspension tends to sediment by the addition of bentonite.

• YAKHAK HOEJI
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• v.39 no.1
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• pp.68-77
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• 1995

Aluminum magnesium silicate was synthesized by reacting the mixed solutions of sodium aluminate and magnesium chloride with sodium silicate solution in this study. The optimal synthesis conditions based on the yield of the product has been attained according to Box-Wilson experimental design. It was found that the optimal synthetic conditions of aluminum magnesium silicate were as follows: Reaction temperature=$69~81^{\circ}C$; concentration of two reactants, sodium aluminate and magnesium chloride= 13.95~14.44 w/w%; molar concentration ratio of the two reactants, [NaAlO$_{2}$]/MgCl$_{2}$]=3.63~4.00; reaction time= 12~15 min; drying temp. of the product=$70~76^{\circ}C$. Aluminum magnesium silicate synthesized under the optimal synthesis condition was dispersed in 0.75, 1.0 and 1.5w/w% aqueous solution or suspension of six dispersing agents, and the Theological properties of the dispersed systems prepared have been investigated at $15^{\circ}C$ and $25^{\circ}C$ using Brookfield LVT Type Viscometer. The acid-consuming capacity of the most excellent product was 272~278 ml of 0.1N-HCl per gram of the antacid. The flow types of 5.0 w/w% aluminum magnesium silicate suspension were dependent upon the kind and concentration of dispersing agents added. The apparent viscosity of the suspension was generally increased with concentration of dispersing agents and was not significantly changed or decreased as the temperature was raised. A dispersing agent, hydroxypropyl cellulose suspension, exhibited an unique flow behavior of antithixotropy. The flow behavior of the suspension dispersed in a given dispersing agent not always coincided with that of the dispersing agent solution or suspension itself.

• YAKHAK HOEJI
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• v.40 no.6
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• pp.659-665
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• 1996

Zinc white is mainly used as a mild astringent, protectant. and has weak antiseptic action. It is well known that the yield of zinc white produced is greatly affected by the syn thetic conditions such as the reactant concentration, reaction temperature, washing water temperature, mole ratio of reactants, and drying temperature, calcination temperature, etc. The purpose of this study is to investigate the optimal synthesis conditions of zinc white produced. A randomized complete block design suggested by G.E.P. Box and K.B. Wilson was applied for this purpose. Basic zinc carbonate was prepared by reacting zinc sulfate and sod. carbonate solution in this study. Zinc white comes when prepared by calcination of basic zinc carbonate. The optimum synthesis conditions of zinc white obtained from this study is as follows: 1) The reacting temperature range is: 92-100$^{\circ}C$, 2) The concentration of reactant solution is 23.6-27%, 3) The optimum mole-ratio: [ZnSO4]/[Na2CO3] is 1.74~1.96, 4) The washing water temperature is 36$^{\circ}C$, 5) The drying temperature range is 68-74$^{\circ}C$, 6) The calcination temperature is 600$^{\circ}C$. The outcome of DSC indicated a desolvation of basic zinc carbonate occurred at about 133.3$^{\circ}C$. The dehydration of the compound ceased at about 267.9$^{\circ}C$ and the decarboxylation ceased at about 379.9$^{\circ}C$. The physical and chemical properties of zinc white as medicine were studied by use of Volume Test.

• YAKHAK HOEJI
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• v.42 no.2
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• pp.153-158
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• 1998

Calcium hydrogen phosphate was synthesized by reacting calcium chloride and sodium hydrogen phosphate solution in this study. It is well known that the particle size and yield o f calcium hydrogen phosphate produced is greatly affected by the synthetic conditions such as the reactant concentration, reaction temperature, reacting fine, mole ratio and drying temperature, etc. The purpose of this study is to investigate the optimum synthesis condition from the viewpoint of yield and sedimentation volume of the prepared calcium hydrogen phosphate powder according to a randomized complete block design proposed by G.E.P. Box and K.B. Wilson. It was found that the optimum synthetic conditions of calcium hydrogen phosphate were as follows: It was found that optirnum temperature range of reactant solutions was $28-38^{\circ}C$ and $32-42^{\circ}C$ respectively, on the viewpoint of yield and sedimentation volume. The optimum concentration range of reactant solutions was 5.5-10.0% and 6.9-7.4% respectively, on the viewpoint of yield and sedimentation volume. The optimum mole ratio of $CaCl_2$ to $Na_2HPO_4$ was in the range of 1.2-2.0 and the optimum reacting time range was 8.5-11.0 minutes. The optimum drying temperature range was $39-41^{\circ}C$ from the viewpoint of yield, but it was $39-43^{\circ}C$ on the basis of sedimentation volume. Crystallographic analysis to X-ray diffraction patterns of commercially available ecalcium hydrogen phosphate and calcium hydrogen phosphate samples prepared in this study suggested that all samples tested belonged to monoclinic crystal system characteristic of $CaHP0_4{\cdot}2H_20$ crystals.

• Microbiology and Biotechnology Letters
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• v.22 no.5
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• pp.531-537
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• 1994

This study was undertaken with objective of optimizing the conditions of fermentation in an aqueous two-phase system which is composed of polyethylene glycol (PEG) 20000 and crude dextran (Dx). The data were obtained and analyzed using the Box-Wilson's experimental design protocol and the response surface methodology. To reach this end a multilinear polynomial regres- sion model was developed, which can be utilized for the purpose of optimizing the extractive fermentation. Optimum conditions for batch fermentation with aqueous two phase system were found to be at 4.2~5.4% PEG/3.2~4.2% Dx range. The composition of the center was 4.8% PEG/ 3.6% Dx. Optimum operating conditions for initial sugar concentration and fermentation time were approximately 160 g/l, and 21~22 hr, respectively. Fermentation in the aqueous two phase system composed of 5% PEG/4% Dx showed increase of 23% in ethanol concentration, of 9.5% in ethanol yield, and of 19% in ethanol productivity as compared to the case of fermentation of neat Jerusalem artichoke juice.

• YAKHAK HOEJI
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• v.41 no.5
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• pp.595-601
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• 1997

The optimal synthesis condition based on the yield of thiamine mononitrate has been attained according to Box-wilson experimental design. The optimal condition was as follows : Molar concentration ratio of $SB1{\cdot}HCL=0.6839$, quantity of $NH_4NO_3=50.09g$, agitation velocity=51.6rpm, reaction temperature=22.8$^{\circ}C$. The stabilities of three kinds of thiamine monosalts(thiamine monoiodide, -monobromide, -monorhodanate) were investigated in sterile solution, compressed tablet and multivitamin capsule, respectively. Assay data are given to show that thiamine monosalts are not significantly higher than that of thiamine mononitrate in sterile solutions and the addition of an acidic stabilizer is unnecessary. The solutions were clear and free of precipitate and didn't discolored after storage at room temperature and 40$^{\circ}C$ for 6 months. The tablets and capsules were assayed initially and at predetermined intervals during storage at room temperature and 40$^{\circ}C$ for 6 months. Thiamine monorhodanate was found to be more stable than other thiamine monosalts in these compressed tablets containing other vitamin of the B complex and the data indicate that thiamine monosalts was similar to that of thiamine mononitrate in the multivitamine capsules.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.34 no.1
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• pp.60-73
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• 1989

Two field experiments were carried out to assess the applicability of a central composite design (CCD) in determining optimum culture condition of an early rice cultivar, Unbongbyeo in southern Korea. A central composite design with two replicates was applied to five levels of five factors such as the number of hills per 3.3m2, the number of seedlings per hill, the levels of nitrogen, the transplanting date and the seedling age (Experiment 1). The levels of planting density were ranged from 30 hills to 150 hills per 3.3m2 ; the number of seedlings per hill from 1 seedling to 9 seedlings per hill; the levels of nitrogen application from 1 kg/l0a to 21 kg/l0a; the transplanting date from June 15 to July 5; the seedling age from 25 days to 45 days. A fractional factorial design was applied to three levels of five factors tested in CCD (Experiment 2). Yield per hill and per unit area were examined and the results obtained from both experiments were compared. The benefits from the central composite design were discussed. Maximum yield of brown rice per unit area was obtained at the combination of the central levels of one of five factors when the other four factors were fixed at central point. Furthermore, brown rice yield per unit area affected by interaction of two factors was maximized at the central point when the remain three factors being fixed at the central level. The responses of five factors to brown rice yield per hill and unit area were found to be a saddle point in both designs. Actual values of the stationary points were 107 hills per 3.3 m2, 4 seedlings per hill, 10 kg nitrogen per l0a, transplanting date of rice on June 26 and 33 days of seedling age in the central composite design. Brown rice yield per unit area at the stationary points were estimated 439 kg/l0a in the central composite design and 442 kg/l0a in the fractional factorial design. Considering the number of experimental treatment combinations, the central composite design was rather convenient in reducing the number of treatment combinations for similar information. It was more convenient for an experimenter to present the results from the central composite design than those from the fractional factorial design. Considering the optimum yields of brown rice per unit area at the stationary points being verified as saddle points in both designs. inter-heterogeneity of each of the factors should be avoided in setting up factors in pursuit of inducing unidirectional response of the factors to yield. Even though both the lower and higher levels in the central composite design being beyond the region of an experimenter's interest. they were considered highly valued in interpretation of the results. Conclusively. the central composite design was found to be more beneficial to optimize culture condition of paddy rice even with several levels of various factors were involved.