• Applied Chemistry for Engineering
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• v.9 no.6
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• pp.817-821
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• 1998

$BaTiO_3$ particles were prepared using $Ba(OH)_2{\cdot}8H_2O$ and $Ti(OC_2H_5)O_4$ by the hydrothermal method and their characteristics treated at the various temperatures have been investigated. This prepared $BaTiO_3$ powder includes a very small amount of $H_2O$ and $OH^-$. By increasing the treated temperature from $200^{\circ}C$ to $1000^{\circ}C$, the mean particle size was accordingly increased from $0.022{\mu}m$ to $0.072{\mu}m$ and the tetrogonality(c/a)was increased from 1.02 to 1.2 so that the phase transition to tetroganal takes place. $BaTiO_3$ sintered at $1250^{\circ}C$ after heat treatment at $400^{\circ}C$ for 3 hrs showed a specific dielectric constant of 8120 and surface activation energy was 9680 kcal/mol.

• 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.

• Journal of the Korea Convergence Society
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• v.9 no.4
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• pp.321-329
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• 2018

This study was attempted to provide data for establishing appropriate guidelines and control standards for accurate information and production of dyes and pigments through the analysis of representative heavy metals and other metals used in cosmetic tattoos. A total of 30 tattoo products for cosmetics were selected from among the representative heavy metals such as arsenic, antimony, cobalt, cadmium, copper, lead, zinc, barium, tin, selenium, chromium and magnesium, manganese(15kinds) were analyzed. As a result of examining the contents of heavy metals in dyes and pigments used in cosmetic tattoo products, it was found that the total of 20products(66.7%) exceeded the reference value and found to be unsuitable for safety standards. It is suggested that the guidance of the specialized agency for safe procedures, appropriate control controls and standards for the dyes and pigments used, and the potential risks of heavy metals are needed.

• Journal of the Korean Ceramic Society
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• v.43 no.7 s.290
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• pp.421-426
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• 2006

[ $(BaSr)TiO_3$ ] thick films were prepared by tape casting method, using $BaTiO_3\;and\;SrTiO_3$ powder slurry in order to investigate dielectric properties i.e. dielectric constant, ${\varepsilon}_r$, Curie temperature, $T_c$. Grain growth within $(BaSr)TiO_3$ thick films was observed with increasing weight ratio of $BaTiO_3$. This observation can be explained by phenomena of substitution of $Sr^{2+}$ ion for $Bi^{2+}$ ion in the $BaTiO_3$ system. Also, the Curie temperature in $(BaSr)TiO_3$ thick films was shifted to lower temperature range with increasing $ SrTiO_3$. Furthermore, Curie temperature having maximum dielectric constant was in the range of $-40^{\circ}C\;to\;30^{\circ}C$, and hence sharper phase transformation occurred at Curie temperature. There occurred decrease in tunability and k-factor of $(Ba_{0.6}Sr_{0.4})TiO_3$ calculated from the dielectric constant, ${\varepsilon}_r$ above Curie temperature. In addition, above the $60^{\circ}C$, phase fixation was observed. This means that internal stress relief occurred with increasing $90^{\circ}$ domains.

• Journal of radiological science and technology
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• v.40 no.2
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• pp.269-274
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• 2017

In this research, we simulated the elementary star shielding ability using Monte Carlo simulation to apply medical radiation shielding sheet which can replace existing lead. In the selection of elements, mainly elements and metal elements having a large atomic number, which are known to have high shielding performance, recently, various composite materials have improved shielding performance, so that weight reduction, processability, In consideration of activity etc., 21 elements were selected. The simulation tools were utilized Monte Carlo method. As a result of simulating the shielding performance by each element, it was estimated that the shielding ratio is the highest at 98.82% and 98.44% for tungsten and gold.

• Journal of Chest Surgery
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• v.35 no.1
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• pp.77-81
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• 2002

We report a case of colobronchial fistula, which is an extremely rare complication of esophagocologastrostomy A 53-year-old man developed recurrent respiratory symptoms 30 months after colon interposition for corrosive esophageal and gastric strictures. Chest radiographs and computed tomography showed an aspiration pneumonia and total atelectasis of the left lower lobe(LLL). Esophagoscopy and barium esophagogram revealed fistula between the colon just below the esophagocolostomy and superior segment of the LLL. The colobronchial fistulectomy and left lower lobe lobectomy were performed. This rare complication should be considered in patients who develop recurrent productive cough whenever they drink or eat something after esophagocologastrostomy.

• Pediatric Gastroenterology, Hepatology & Nutrition
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• v.13 no.2
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• pp.199-203
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• 2010

Sigmoid volvulus may cause acute or subacute colonic obstruction. Excessive length of the sigmoid colon may be a contributing factor. Typically, the patient develops bilious vomiting and marked gaseous abdominal distension. We report a case of sigmoid volvulus in a 9-year-old boy who presented with recurrent, sudden onset abdominal pain, abdominal distension, and vomiting for 1 year, which was diagnosed by simple abdominal X-ray, barium enema, computed tomography, and colonoscopic examination. Colonoscopic reduction failed and a sigmoid colectomy with primary repair was performed. The intra-operative findings showed that the sigmoid colon was noted to be dilated, and redundant with a lax mesentery. Two clear areas of compression (proximal and distal) were present. After sigmoidectomy, the symptoms resolved. After 5 years of follow-up, he had no new symptoms.

• Analytical Science and Technology
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• v.5 no.4
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• pp.409-415
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• 1992

Factor analysis was applied to X-ray diffraction patterns of the precursor of $BaTiO_3$. For that purpose, the precursor was synthesized in water solvent system using $Ba(NO_3)_2$ and $TiO(NO_3)_2$ as the starting materials and calcined at various temperatures. The samples obtained from the various calcined temperatures were analyzed by the X-ray diffractometer. Factor analysis was applied to the intensity data of the X-ray diffraction patterns. As the results, three factors were found and they were found to be $BaCO_3$, $BaTiO_3$ and $Ba_2TiO_4$. The relative concentrations of the three components were estimated during calcination.

• Journal of the Korean Chemical Society
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• v.42 no.6
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• pp.652-656
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• 1998

$(Ba_{0.8-x}Sr_{0.2})Y_xTiO_3\;(BSYT)$ powders were prepared by the calcination of metal-oxalate precipitates, which were obtained by wet chemical method using Ba, Sr, Y and Ti-nitrates and oxalic acid. Yttrium content, sintering temperature and cooling rate were taken as experimental factors. Response surface method was applied to modelling of the room temperature resistivity of BSYT. The results indicated that the Yttrium content had larger effect on the room temperature resistivity and minimum room temperature resistivity was at Yttrium content of 0.24 mol%. The validity of a modelling equation was confirmed by comparing the measured room temperature resistivity with the calculated one.

• Korean Chemical Engineering Research
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• v.56 no.3
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• pp.349-355
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• 2018

$BaMnAl_{11}O_{19}$ was prepared by urea-induced homogeneous precipitation and characterized by X-ray diffraction and scanning electron microscopy. At increased precipitant concentrations, AlOOH replaced $Al(OH)_3$ as an Al precursor. $BaMnAl_{11}O_{19}$ exhibited enhanced catalytic combustion performance and inhibited CO generation. Catalytic performance was also enhanced by the presence of $BaAl_2O_4$ and $BaMnAl_{11}O_{19}$. Compared to $BaAl_2O_4$, $BaMnAl_{11}O_{19}$ exhibited superior catalytic combustion activity.