• The tire
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• s.111
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• pp.20-29
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• 1984

유한요소법에 의하여 축대칭 정적하중을 받는 승용차용 래디알 타이어의 변형을 해석하였다. 요소는 8절점 parabolic-isoparametric 요소를 사용하였으며 타이어를 구성하는 cord-rubber복합체를 선형직교성을 갖는다고 가정하고, 그 복합체의 물성치를 간단한 식으로 표시하여 적용하였다. 공기압으로 인해 변형된 모양 및 cord에 작용하는 장력을 계산해 냈으며 이 변형된 모양을 plaster cast를 이용하여 측정한 실험치와 비교하였다. 또 타이어를 구성하는 구조가 달라지면 공기압으로 인하여 변형형태가 어떻게 변화하는가를 계산해 보았다. 이 결과로 belt의 cord수가 감소하거나 belt cord angle이 증가하면 타이어 외경이 증가함을 알 수 있다.

• Korean Journal of Human Ecology
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• v.16 no.3
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• pp.577-585
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• 2007

This research aimed for 20 latter man whose body shape of torso alters remarkably to develop nipper pattern of running type considered characteristic of body shape of 20 latter man to keep rather balanced body shape against middle age when body shape changes extremely. 1. running type nipper pattern design. Pattern of running, lining and nipper were designed by flattening surface shell. A basis line of running pattern is completed by applying reduction ratio after 3 times of modification & complement based on surface shell. Nipper pattern is designed with design line set by a plaster cast based on running pattern line. Lining pattern is designed with lining design line set by a plaster cast based on running type outside material and nipper pattern. 2. Functional evaluation of research and commercial nipper. Functional inspection through dress test was applied 5point evaluation method and the result of functional inspection on the sight of a wearer is that research nipper(running reduction ratio 15%, nipper reduction ratio 18%) averaged more 4.8point but commercial nipper averaged less 1.8point in the aspect of 20 items such as wear sensibility, motional function and external appearance aesthetic. Research running type nipper scored high in order of motional function, looks of side, back, front and whole and wear sensibility. Functional inspection in the point of view of an observer is that research nipper(running reduction ratio 15%, nipper reduction ratio 18%) averaged over 4.8point and commercial nipper averaged under 1.9point in 17 items of external appearance beauty. Research running type nipper marked high in order of looks of back, whole, front and side.

• Imaging Science in Dentistry
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• v.49 no.4
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• pp.257-263
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• 2019

Purpose: This study was performed to evaluate the dimensional accuracy of digital dental models constructed from cone-beam computed tomographic (CBCT) scans of polyvinyl siloxane (PVS) impressions and cast scan models. Materials and Methods: A pair of PVS impressions was obtained from 20 subjects and scanned using CBCT (resolution, 0.1 mm). A cast scan model was constructed by scanning the gypsum model using a model scanner. After reconstruction of the digital models, the mesio-distal width of each tooth, inter-canine width, and inter-molar width were measured, and the Bolton ratios were calculated and compared. The 2 models were superimposed and the difference between the models was measured using 3-dimensional analysis. Results: The range of mean error between the cast scan model and the CBCT scan model was -0.15 mm to 0.13 mm in the mesio-distal width of the teeth and 0.03 mm to 0.42 mm in the width analysis. The differences in the Bolton ratios between the cast scan models and CBCT scan models were 0.87 (anterior ratio) and 0.72 (overall ratio), with no significant difference (P>0.05). The mean maxillary and mandibular difference when the cast scan model and the CBCT scan model were superimposed was 53 ㎛. Conclusion: There was no statistically significant difference in most of the measurements. The maximum tooth size difference was 0.15mm, and the average difference in model overlap was 53 ㎛. Digital models produced by scanning impressions at a high resolution using CBCT can be used in clinical practice.

• Advances in concrete construction
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• v.6 no.1
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• pp.87-102
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• 2018

Utilization of waste tires may be considered as one of the solution to the problems faced by the local authorities in disposing them. Reclaimed rubber (RR) is being used in concrete for replacing conventional aggregates. This research work is focused on the strength prediction of reclaimed rubber concrete using a Genetic Algorithm (GA) for M40 grade of concrete and comparing it with experimental results. 1000 sets were taken and 100 iterations were run during training of GA models. A base study has been carried out in this research work partially replacing cement with three types of fillers such as Plaster of Paris (POP), Fly Ash (FA) and Silica Fume (SF). A total of 243 cubes were cast and tested for compression using a Universal Testing Machine. It was found that SF produced maximum strength in concrete and was used in the main study with reclaimed rubber. Tests were conducted on 81 cube samples with a combination of optimum SF percent and various proportions of RR replacing coarse aggregates in concrete mix. Compressive strength tests of concrete at 7, 14 and 28 days reveal that the maximum strength is obtained at 12 percent replacement of cement and 9 percent replacement of coarse aggregates respectively. Moreover the GA results were found to be in line with the experimental results obtained.

• Journal of the Korean Home Economics Association
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• v.30 no.3
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• pp.63-77
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• 1992

The purpose of this study is to improve clothing construction by analyzing form variation of upper trunk & upper arms with the use of plaster cast. Experimental research was performed by plaster gypsum method. The subjects were males between age 21 and 25, classified Standard somatotype by their bust size and Rorher Index. Arm movements were consisted of 5 types(0$^{\circ}$, 45$^{\circ}$, 90$^{\circ}$, 135$^{\circ}$, 180$^{\circ}$) to each vertical motion in front. The statistical analyses used in this study were mean, standard deviation, repeated mesure design. The result obtained from this study were as follows; 1. As a result of investigating into the rate of the expantion and contraction of basic body-surfact-lines, the side seam length showed the maxium rate of expantion in 180$^{\circ}$ degrees, the shoulder length showed the maxium contraction in the same degrees. 2. The variation of the upper part of the body form by increasing the upper limb motions, shoulder point was moved to be the inside or upside. And the anterior armfit point, posterior armfit point and armfit point were moved to upside. The form of the armhole-line in Drafts of a body surface was differently changed by increasing the movements. 3. Increasing the upper limb motions, the height of sleeve cap decresed and width of the sleeve decreased but girths of the sleeve cap was not show consistant change.

• Archives of Plastic Surgery
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• v.34 no.1
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• pp.18-23
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• 2007

Purpose: Anthropometry can be divided into two methods, direct anthropometry and indirect anthropometry. The most ideal and accurate method is a direct anthropometry. However, it is difficult to measure in the case of children because of poor cooperation, and it lacks re-productivity. Cast model has advantages of three dimensional featuring, inexpensive and easy fabrication. This study is conducted to find out an accuracy of indirect anthropometry on cast model by comparing it with direct anthropometry. Methods: Total 48 cleft lip nasal deformity patients (unilateral, 40; bilateral, 8) were included in this study. Cast models were made before surgery under general anesthesia with alginate impression material and model plaster. Eleven linear measurements among 7 landmarks were taken as direct anthropometry before surgery with Castroviejo spreading caliper. At the same time, indirect anthropometry on cast model was done at the same linear distances as well. Results: Of the total 11 linear measurements, both ala lengths, both columella lengths, nose width, projective distance between facial insertion points of the ala, projective distance between the alar base points, right nostril floor width, and columella width were statistically correlated between indirect anthropometry on cast model and direct anthropometry. However, the nasal tip protrusion and the left nostril floor width were not statistically correlated. Conclusion: Accuracy of indirect anthropometry on cast model can be influenced by cast model fabrication techniques and correct identification of landmarks. Nasal tip protrusion could be reduced by compression of the nasal tip in the process of cast model fabrication and nostril floor width can be varied by muscle relaxation of anesthetics and incorrect identification of subalare in cleft lip nasal deformity. If sufficient care is taken to make cast model and to define landmarks exactly, indirect anthropometry on cast model can be a reliable method as direct anthropometry.

• Archives of Plastic Surgery
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• v.35 no.1
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• pp.48-55
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• 2008

Purpose: We measured linear distances, angles and inclinations on the cast models of the noses, and compared these indirect measurements with the direct measurements obtained from the nose in order to validate the accuracy of the indirect anthropometry using the cast model. Methods: Subjects were 50 males and 50 females, medical students in twenties(mean 27.1 years). Cast models were made from the alginate impression material and the plaster. In direct anthropometry, 16 linear, 7 angular, and 2 inclination measurements between 11 landmarks on the nose were obtained using sliding caliper, spreading caliper, and fabric tape measure. At the same time, the same measurements were obtained from the cast models of the same people. Total 25 measurements were compared, and tested by the independent t-test of SPSS. Results: The standard values of Korean nose in twenties were obtained. 24 measurements except the columellar labial angle were not statistically different between the indirect anthropometry and the direct anthropometry. Conclusion: Indirect anthropometry on the cast model of the nose revealed no significant difference from the anthropometric measurement statistically, accounting for 24 in 25 measurements(96%). There are two possible reasons that caused the difference of columellar labial angle between direct and indirect anthropometry. First, the columellar labial angle could be decreased by protrusion of the lips which resulted from contracting mouth in which an drinking straw had been applied on the mouth corner for patients' respiration during making cast model. Second, it is generally known that the columellar labial angle could be measured larger when soft tissues were pressed by protractor in direct anthropometry. Using a drinking straw with greater diameter, and scheming respiration through the nostrils that patients don't feel discomfort, the more accurate data would be obtained from the indirect anthropometry using the cast models of the noses.

• Journal of KIISE
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• v.43 no.5
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• pp.516-523
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• 2016

For old-age makeups, makeup artists first make a mold cast of an actor's face using plaster and then sculpt wrinkles in clay on the plaster mold. After finishing the clay sculpture, its negative plaster mold is fabricated and silicone skin patches are finally made for application to the actor's face. This process takes a few days and is tedious for actors and makeup artists. With recent advances in 3D printing and scanning technology, it is becoming easier to scan and fabricate 3D faces. This paper presents a new pipeline composed of facial scanning, interactive wrinkle modeling, and mold printing stages to easily and efficiently fabricate silicone masks for old-age makeups without the use of plaster and clay. An intuitive sketch interface based on a normal map is proposed for the creation of wrinkles in real time, even with a high-resolution face model. Then the geometry of the final wrinkles is reconstructed using a depth map and the negative mold of the wrinkled face is printed. We also show that the presented pipeline can fabricate a silicone mask more conveniently than the traditional one that consists of pouring silicone into the prepared negative mold and then overlapping the mold with the original positive one.

• The Journal of Advanced Prosthodontics
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• v.10 no.4
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• pp.279-285
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• 2018

PURPOSE. The aim of this clinical study was to assess the accuracy of the implants placed using a universal digital surgical guide. MATERIALS AND METHODS. Among 17 patients, 28 posterior implants were included in this study. The digital image of the soft tissue acquired from cast scan and hard tissue from CBCT have been superimposed and planned the location, length, diameter of the implant fixture. Then digital surgical guides were created using 3D printer. Each of angle deviations, coronal, apical, depth deviations of planned and actually placed implants were calculated using CBCT scans and casts. To compare implant positioning errors by CBCT scans and plaster casts, data were analyzed with independent samples t-test. RESULTS. The results of the implant positioning errors calculated by CBCT and casts were as follows. The means for CBCT analyses were: angle deviation: $4.74{\pm}2.06^{\circ}$, coronal deviation: $1.37{\pm}0.80mm$, and apical deviation: $1.77{\pm}0.86mm$. The means for cast analyses were: angle deviation: $2.43{\pm}1.13^{\circ}$, coronal deviation: $0.82{\pm}0.44mm$, apical deviation: $1.19{\pm}0.46mm$, and depth deviation: $0.03{\pm}0.65mm$. There were statistically significant differences between the deviations of CBCT scans and cast. CONCLUSION. The model analysis showed lower deviation value comparing the CBCT analysis. The angle and length deviation value of the universal digital guide stent were accepted clinically.

• Journal of Technologic Dentistry
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• v.34 no.2
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• pp.75-81
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• 2012

Purpose: All ceramic crown, made from zirconia instead of metal for core material, is recognized the best esthetical prosthesis. Recently, high-priced zirconia blocks and expensive CAD/CAM machines come into use for making zirconia core. In this study, slip casting process is adapted to evaluate the possibility of the recycling the remained parts of zirconia block after machining. Methods: Remained zirconia blocks were reduced to powders with zirconia mortar, and screened with 180 mesh sieve. Passed powders were ball milled under various conditions to obtain the optimum zirconia slip for casting. Solid casting method was used for casting the specimens with plaster mold. Formed specimens were dried and biscuit fired at $1,000^{\circ}C$ for 1 hour. Biscuit fired specimens were finished with exact shape of square pillar. Finished specimens were fired from $1,200^{\circ}C$ to $1,550^{\circ}C$ at $50^{\circ}C$ intervals for 1 hour. Linear shrinkage, apparent porosity, water absorption, bulk density, and flexural strength were tested. Microstructures were observed by SEM. Results: Above examinations indicated that the optimum firing temperture was $1,500^{\circ}C$, and when fired at this temperature for 1 hour, apparent porosity was 0% and flexural strength was 680MPa. SEM photomicrographs showed uniform 200~300nm grain size, which is equal with microcture of sintered commercial zirconia block. when compare 24% linear shrinkage of cast specimen with 20% linear shrinkage of CAD/CAM machined block, it was estimated that the size controlling of cast core was not so difficult. Conclusion: According to the all of this experimental results, the cast zirconia core produced from the remained parts of zirconia block was possible to use for all ceramic denture.