• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1993년도 봄 학술발표회 논문집
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• pp.99-105
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• 1993

The purpose of this fundamental study is to investigate the mechanism of high strength concrete using the high calcium sulfate cement from a point of view in cement hydration and micro structure. As a results, it was found that the internal pores of concrete are decreased by using the high calcium sulfate cement, because the hydrates of Ettringite which is densified in structure is much formed in early ages at steam curing. In addition to the ettringite needs the 32 times of free water formed mixing water for hydration. This effect are not only decreased the water to cement ratio and also increase to comp, strength of concrete. It was conclude that these above the two facts are the main mechanism of high strength concrete using high calcium sulfate cement.

• 한국가구학회지
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• 제19권1호
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• pp.83-90
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• 2008

Gypsum-wood composites were made by introducing inorganic substances into wood using calcium chloride, first treating solution, and sodium sulfate, secondary treating solution, by double diffusion process under atmospheric pressure at room temperature. The process conducted as follows: water saturated specimens were soaked in calcium chloride solutions at several concentration. Then the specimens were soaked further in saturated sodium sulfate solution, and they were leached in flowing tap water for 24h. To attain sufficient weight percent gain (WPG) values, the suitable concentration of calcium chloride and soaking time in saturated sodium sulfate solution were 20% and 48h, respectively. Inorganic substances were produced mainly in the lumina of tracheides. It was made sure that these substances were dihydrate gypsum($CaSO_4$ $2H_2O$) by X -ray microanalysis (SEM-EDX). The composites had good fire resistance due to low heat transfer rate of gypsum formed in wood. However, the composites had little decay resistances, because they showed high weight losses by test fungi attacks.

• Journal of Periodontal and Implant Science
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• 제32권2호
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• pp.429-455
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• 2002

There are numerous kind of materials and techniques to regenerate the periodontal tissue which has been lost due to destructive periodontal disease, including bone graft material. Many bone graft materials have been reported and among these materials, synthetic material has been developed fin the long time because of its sufficient supply economically. Calcium sulfate which was evaluated as including much calcium, has been used in the clinical field. In the dental field calcium sulfate has been used as bone graft material and Kim reported that improved bone formation and more amount of new attachment after grafting calcium sulfate. but, because calcium sulfate has the problem that it generates the heat in setting period and resolves fast, we need to evaluate the effect of the improved calcium sulfate on periodontal tissue. The present study evaluates the effect of paste type calcium sulfate on the epithelial migration, alveolar bone regeneration, cementum formation and gingival connective tissue attachment in intrabony defect in dogs. Four millimeter deep and four millimeter wide 3-wall defects were surgically created in the mesial or distal aspects of premolars or molars. the test group received paste-type calcium sulfate with a flap procedure and the control group underwent flap procedure only. Histologic analysis after 8 weeks of healing revealed the following results : 1. The length of epithelial growth(the distance from CEJ to the apical end of JE) was 0.52${\pm}$0.26mm in the control and 0.56${\pm}$0.25mm in the test group. there was no statistically significant difference between the two groups. 2. The length of connective tissue adhesion was 1.74${\pm}$1.06mm in the control and 1.28${\pm}$0.57mm in the test group. there was no statistically significant difference between the two groups. 3. The length of new bone was 2.01${\pm}$0.95mm in the control and 2.62${\pm}$0.81mm in the test group. there was no statistically significant difference between the two groups. 4. The length of new cementum was 1.86${\pm}$0.80mm in the control and 2.77${\pm}$ 0.86mm in the test group. there was a statistically significant difference between the two groups.(P<0.01) These results suggest that the use of paste type calcium sulfate in 3-wall intrabony defects has significant effect on new cementum formation , but doesn't have any significant effect on the prevention of junctional epithelium migration and new bone formation. Finally, the paste type calcium sulfate that is used in this study is suggested to be the material that can have a significant effect on the periodontal healing, if its biocompatibility is improved.

• 한국구조물진단유지관리공학회 논문집
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• 제23권7호
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• pp.72-79
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• 2019

콘크리트는 경화 중의 온도변화나 수축에 의한 체적변화, 외부 힘의 작용, 시공불량 등에 의해 균열이 발생할 가능성이 높다. 특히, 전력구 구조물에 시공되는 콘크리트는 다양한 요인에 의해 균열이 발생되고 있어 지속적인 유지관리가 필요한 실정이다. 이에 본 연구에서는 산업부산물로서 팽창성능이 있는 알파형 반수석고를 활용한 콘크리트의 역학적 특성에 대해 검토하였다. 기존 연구결과를 바탕으로 알파형 반수석고를 치환시 압축강도가 감소하는 점을 보완하기 위하여 시멘트의 사용량은 동일하게 고정한 후 알파형 반수석고를 9% 첨가하고, 혼화제의 사용량을 조절한 후 콘크리트의 역학적 특성을 평가하였다. 실험 결과, 콘크리트의 압축강도가 OPC와 동등이상의 수준으로 나타났으며, 알파형 반수석고를 9% 첨가시 OPC 대비 약 30% 이상의 수축이 저감되어 콘크리트의 균열 저감에 효과가 있을 것으로 판단된다.

• 한국임상수의학회지
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• 제19권2호
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• pp.165-173
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• 2002

The purpose of this study was to evaluate the effect of chitosan-calcium sulfate mixture on early bony consolidation in osteodistracted dogs. The experimental group was divided into 3 groups: saline group(Control), chitosan group(Group CH) and chitosan-calcium sulfate mixture group(Group CH+CS). Four dogs were allocated to each group and classified into B week observation subgroups and 5 week observation subgroups, respectively. Two dogs were allocated to each subgroup. The lateral surface of the left mandibular body was exposed in the subperiosteal plane and vertical osteotomy was carried out on the mandibular body. An external distraction device was applied to the mandibular body. Mandibular distraction was started 5 days after the osteotomy at a rate of 1 m per day for a total of 10 w distraction for 10 days. After completion of distraction, chitosan, chitosan-calcium sulfate and saline were injected into the distracted zone of the group CH, group CH+CS and control. The external device was left in place for 3 or 5 weeks to allow for bony consolidation. Serial radiographs were carried out every week. Two dogs of each group, six dogs in total, were sacrificed at 3 weeks, and the other six dogs at 5 week after distraction. Bone specimens of the distracted mandibles were taken for histologic examination. New bone was not noted in the distracted zone of 3 week observation subgroups in the control and group CH. However, new bone was developed in the group CH+CS with a narrow fibrous interzone in the area of the distracted zone. While osteogenesis was mild in the margin of the distracted Bone of 5 week observation subgroup in the control, new bone was noted much in the group CH and group CH+CS. However, osteogenesis was noted more significantly in the group CH+CS than that of group CH. In conclusion, chitosan-calcium sulfate mixture was more effective on early bony consolidation in distraction osteogenesis

• 한국재료학회:학술대회논문집
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• 한국재료학회 2009년도 춘계학술발표대회
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• pp.45.1-45.1
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• 2009

In this study, we investigated a calcium phosphate-calcium sulfate injectable bone substitute (IBS) with organic reinforcement of chitosan, citric acid and hydroxypropyl-methyl-cellulose (HPMC). The powder component of IBS consisted of tetra calcium phosphate (TTCP), dicalcium phosphate dihydrate (DCPD) and calcium sulfate dihydrate (CSD). The liquid component was a solution of citric acid and chitosan. The effect of HPMC in terms of setting time, compressive strength and apatite forming ability on this IBS was investigated. The mass content of HPMC in liquid phase was varied in array of 0%, 2%, 3% and 4%. The setting times obtained between 20 and 45 minutes. Compressive strength was achieved over 20 MPa after incubation at 370C and in 100% humidity for 28 days. Porosities were evaluated in relation with compressive strength. Elastic moduli of the 28 days after-incubation IBS were obtained around 4GPa

• Journal of Veterinary Science
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• 제24권6호
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• pp.74.1-74.15
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• 2023

Background: Antibiotic beads are used to treat local bacterial infections by delivering high drug concentrations to infected tissue. Objectives: This study examined the elution characteristics of metronidazole from metronidazole-calcium sulfate (MCa) and metronidazole-calcium-potassium sulfate (MCaK) beads over 20 days and the antibacterial efficacy of the beads after storage. Methods: The MCa and MCaK beads were prepared by mixing 250 mg of metronidazole and 10 g of calcium sulfate hemihydrate with water and a 3% potassium sulfate solution, respectively. The beads were placed in phosphate-buffered saline for the elution study. The metronidazole eluents were determined using high-performance liquid chromatography. The microstructures were examined by scanning electron microscopy (SEM), and the antimicrobial activity was evaluated by a microbioassay. Results: For the 20-day study, the total amount of metronidazole released was greater in the MCa beads than in the MCaK beads by 6.61 ± 0.48 mg (89.11% ± 3.04%) and 4.65 ± 0.36 mg (73.11% ± 4.38%), respectively. The amounts of eluted drugs from the MCa and MCaK beads were higher than the minimum inhibitory concentration at 0.5 ㎍/mL against anaerobic bacteria at both 20 days and 14 days. SEM showed that calcium crystals on the outer surface had dissolved after elution, and thinner calcium crystals were prominent in the MCaK beads. The MCa and MCaK beads exhibited antibacterial activity after setting, followed by storage at room temperature or 4℃ for 21 days. Conclusions: The MCa beads could release more drug than the MCaK beads, but all eluted metronidazole amounts were effective in controlling bacterial infections. Both metronidazole beads could be stored at ambient temperature or in a refrigerator.

• 환경위생공학
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• 제17권3호
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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.

• Applied Biological Chemistry
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• 제37권5호
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• pp.370-378
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• 1994

두유에 우유를 40% 첨가시킨 두부 제조를 위하여 각 응고제별 및 첨가농도별로 두부를 제조하여 gel형성, 순물(whey)의 탁도, 단백질함량, 두부 생산량, 무기질함량, 조직특성과 색도를 비교 조사하였다. Calcium염 응고제는 0.3%(v/v), magnesium chloride는 0.4%, 유기산 응고제는 0.2% 첨가수준에서 대두와 우유 단백질의 공침전이 일어났으며 각 응고제 첨가비율에 비례하여 whey 탁도와 단백질의 유출량이 낮아졌다. 각 응고제 첨가 적정수준은 calcium acetate, calcium sulfate, calcium lactate 가 각각 1.2%(v/v), calcium chloride, gluconodelta-lactone이 각각 1.0%(v/v), magnesium chloride, lactic acid 0.8%(v/v), acetic acid는 0.6%(v/v)였으며 두부 생산량은 calcium chloride를 응고제로 사용했을 때 가장 높았다. 무기질의 함량은 calcium염 응고제가 유기산 응고제보다 Ca은 약 3.3배 많았고 K, Mg, Na, Fe도 약간 높았다. Texturemeter에 의한 우유 첨가 두부의 조직특성 조사결과 가장 단단한 두부는 acetic acid 두부이었고 calcium염 중에서는 calcium sulfate가 단단하였다. 응고제별 두부의 색도 비교에서 명도는 유기산 두부가 약간 높았고 적색도와 황색도는 calcium염 두부가 높았다.

• Journal of Periodontal and Implant Science
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• 제33권4호
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• pp.693-703
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• 2003

The present study evaluated the effects of guided tissue regeneration using xenograft material(deproteinated bovine bone powder), with and without Calcium sulfate membrane in beagle dogs. Contralateral fenestration defects (6 ${\times}$ 4 mm) were created 4 mm apical to the buccal alveolar crest of maxillary premolar teeth in 5 beagle dogs. Deproteinated bovine bone powders were implanted into fenestration defect and one randomly covered Calcium sulfate membrane (experimental group). Calcium sulfate membrane was used to provide GTR. Tissue blocks including defects with soft tissues which were harvested following four & eight weeks healing interval, prepared for histo-phathologic analysis. The results of this study were as follows, 1. In control group, at 4 weeks after surgery, new bony trabecular contacted with interstitial tissue and osteocytes lie cell were arranged in new bony trabecule. Bony lamellation was not observed. 2. In control group , at 8 weeks after surgery, scar-like interstitial tissue was filled defect and bony trabecule form lamellation. New bony trabecular was contacted with interstitial tissue but defect was not filled yet. 3. In experimental group, at 4 weeks after surgery, new bony trabecular partially recovered around damaged bone. But new bony trabecule was observed as irregularity and lower density. 4. In experimental group, at 8 weeks after surgery, lamella bone trabecular developed around bone cavity and damaged tissue was replaced with dense interstitial tissue. In conclusion, new bone formation regenerated more in experimental than control groups and there was seen observe more regular bony trabecular in experimental than control groups at 4 weeks after surgery. In control group, at 8 weeks after surgery, the defects was filled with scar-like interstitial tissue but, in experimental group, the defects was connected with new bone. Therefore xenograft material had osteoconduction but could not fill the defects. We thought that the effective regeneration of periodontal tissue, could be achieved using GTR with Calcium sulfate membrane.