• Journal of the Korea institute for structural maintenance and inspection
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• v.17 no.6
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• pp.130-137
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• 2013

This research was performed through the experimental design to get the statistical analysis on foamed concrete mixed plaster with hydrogen peroxide. In this experiment, we set the ratio of each material, which part of lightweight concrete, as experimental factors and evaluated on the mechanical properties by statistical analysis for response variables obtained from experiments. Experimental factors are plaster replacement, water binder ratio, and hydrogen peroxide ratio. Response variables are dry density, compressive strength, and flexural strength. Mixing design of the foamed concrete set up a total of 15 experimental points by Box-Behnken (BB) method of the response surface analysis. Thus, the results of a study were summarized as follows. Values of the probability in experimental factors (plaster replacement, water binder ratio and hydrogen peroxide ratio) on the response variables were estimated to be significant at the 95% of confidence limit. On response surface analysis for dry density of foamed concrete, water binder ratio and hydrogen peroxide ratio were estimated to be significant (${\alpha}$ = 0.05), and the relationship between the amount of void and the water content for dry density is inverse proportional. On response surface analysis for the compressive strength of foamed concrete, water binder ratio, hydrogen peroxide ratio and (hydrogen peroxide ratio)$^2$ was estimated to be significant (${\alpha}$ = 0.05). On response surface analysis for the flexural strength of foamed concrete, water binder ratio, hydrogen peroxide ratio was estimated to be significant (${\alpha}$ = 0.05). Through multi response surface analysis, we found the optimal area that meets performance goals.

• The Journal of Engineering Geology
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• v.32 no.4
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• pp.597-610
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• 2022

Knowledge of the failure behavior of friction materials considering their intermediate principal stress is related to an understanding of situations where these materials might be used: for example, the stability of deep-seated boreholes and fault slip analysis. This study designed equipment for physically implementing true triaxial compression and used it to assess specimens of plaster, a friction material. The material's mechanical behaviors are discussed based on the results. The applicability of the 3D failure criteria are also reviewed. The tested specimens were molded cuboids of width, length, and height 52, 52, and 104 mm, respectively. A total of 24 true triaxial compression tests were performed under various combinations of 𝜎₃ and 𝜎₂ conditions. Conventional uniaxial and triaxial compression tests were employed to estimate the mechanical properties of the plaster for use as parameters for 3D failure criteria. Examining the stress-strain relations of the plaster materials showed that a large difference between the intermediate principal stress and the minimum principal stress indicated strong brittle behavior. The mechanical behavior of the plaster used here reflects the change of intermediate principal stress. Nonlinear multiple regression analysis on the test data in the principal space showed that the modified Wiebols-Cook failure criterion and the modified Lade failure criterion were the most suitable 3D failure criteria for the tested plaster.

• 대한치주과학회:학술대회논문집
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• 2005.11a
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• pp.66-67
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• 2005

• Journal of Technologic Dentistry
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• v.10 no.1
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• pp.43-46
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• 1988

The purpose of this investigation was to determined the dimensional change of plaster to time with impression materials. This study was carried out through the literature & experiment, using 4sorts of the Impression Materials(Alginate, Impression Agar, Silicone Rubber, Polysulfide Rybber)and 5 treatments(1hr, 11/2 hrs, 2hur, 3hur, 6hur). The results of this experiment were as follows : 1. Main effect of Impression Meterials & tretments was statistically significant.(P<0.01). 2. The effect of 2-way interaction of Impression materials & Treatments was also statistically significant.(P<0.01) 3. Though this study was the difference of degree according to the materials. All Impression Materials were tended to be constained according to over the time.

• The Journal of the Korean dental association
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• v.16 no.12 s.115
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• pp.941-944
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• 1978

The author studied skin reactions and their incidences among 100 dental students and dental nurses to 2% Lidocaine HC1, 3% H₂O₂, Euginol, 5% Sodium Hypochlorite, Dycal and Adhesive plaster by means of Patch test. Following are the results of the study. 1. Eighty six cases out of 100 revealed slight response to 1 or 2 allergens. 2. 2% Lidocaine HC1 showed 1 case, 3% H₂O₂cases, Euginol 2 cases, 5% Sodium Hypochlorite 74 cases, Dycal 1 case Adhesive plaster 8 cases. 3. 5% Sodium Hypochlorite was the most influential to skin. 32 cases showed grade 1+, 20 cases showed grade 2++, 16 cases showed grade 3+++, 6 cases showed grade 4++++,

• 한국문화재보존과학회:학술대회논문집
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• 2005.03a
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• pp.1-11
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• 2005

No one can tell when, exactly, the conservation of potteries & ceramics began, however, according to the documents, it has a long history. Among the materials discovered up to the present, organic adhesives extracted from animals and plants such as bitumen were mainly used and resin, in 19th century, as well. As for inorganic adhesives, clay, lime and plaster were used as well as rivet, as one of mechanical methods. According to the conservation case studies in Korea, lacquer and gilding powdered gold were applied as treatment methods in some ceramics, but, in general, plaster and resins were used widely.

• Tunnel and Underground Space
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• v.7 no.3
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• pp.221-229
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• 1997

Disc-type and ring-type specimens of four different materials were tested to investigate the tensile characteristics and their brief results are presented. Materials tested were marble, granite, cement mortar and plaster. Unizxial tensile strengths are compared with Brazilian and ring test strengths. It was found that Brazilian strengths were usually greater than uniaxial tensile strengths and affected by loading rates. In the ring tests, tensile strengths were generally found to be decreased as relative hole radius being increased. Ring test strengths, however, converged to some value in r$\geq$0.45 of marble, r$\geqq$0.29 of cement mortar and r$\leq$0.5 of plaster specimens. In such range of r, furthermore, transverse cracking of specimens were observed.

• Transactions of Materials Processing
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• v.10 no.6
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• pp.500-508
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• 2001

The integration of Rapid prototyping (RP) and Rapid Tooling (RT) has the potential for rapid net shaping of thee-dimensional parts, which have a geometrical complexity. In this study, a new R)P process, (VLM-SP), was proposed to manufacture net shapes of three-dimensional prototypes and it was shown that VLM-SP is an effective and economic process through the comparison of building time, building cost and dimensional accuracy for the test parts with the commercial RP processes ; LOM and FDM. In addition, the metal parts, which are a spanner shape and a clover punch, were produced by the plaster casting as one of RT using the prototypes of VLM-SP.

• The Journal of Korean Academy of Prosthodontics
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• v.9 no.1
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• pp.9-15
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• 1969

The purpose of this study was to examine arch form, occlusion in centric occlusion. Male 561 case, Female 305 case were impressioned with alginate impression material, and plaster models were made. Occlusion and maxillary dental arch were studied on plaster models in Korean adults aged from 18 to 60 Years. The results were as follows. 1. The upper dental arch was U-type(57.77%), O-type(23.52%), V-type(18.71%) in male, and U-type(60.66%), O-type(27.11%), V-type(12.13%) in female. 2. The commonest type of the anterior bite was 1-form($68.09{\pm}1.97%$) in male, ($72.46{\pm}2.56%$) in female, and posterior bite was 1-form($65.06{\pm}2.01%$) in male, ($69.51{\pm}2.64%$ in female. 3. In the maxillary dental arch U-type was frequented and the relationship of occlusion in upper and lower dental arch was mainly 1-form.

• Journal of the Korean Society of Costume
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• v.31
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• pp.89-99
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• 1997

In order to know what sorts of features of neck fore may be required to make plans for tight fitting collars the neck form of young japanese women were measured three deme-nsionally using. GRASP(Grating projection System for Profiling) and plaster torso. The following results were obtained: 1. We could be known the features of neck form for tight fitting collars by using both plaster torso method and GRASP method. 2. By the BASIC language in NEC computer and EXCEL package program in macin-TOSHI computer it became possible to draft a numble of neck surface automatically there-fore we got analysis of a mass of subjects.