• The Journal of Korean Academy of Prosthodontics
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• v.43 no.4
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• pp.478-486
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• 2005

Statement of problem : Fracture and dimensional change of an acrylic resin denture are a rather common occurrence. Purpose : The purpose of this study was to compare differences in dimensional changes and flexural strength of separate maxillary complete dentures after immediate deflasking by injection molding and conventional compression processing. Material and method: To evaluate dimensional stability, the maxillary dentures were fabricated by using different materials and methods. Lucitone 199(Dentsply Trubyte. york, pennsylvania, USA) and Vertex(Dentimex, zeist, Netherlands) were used as materials. Compression and injection packing methods were used as processing methods. The impression surface of the dentures was measured by 3D Scann-ing System(PERCEPTRON USA) and overlapped original impression surface of the master cast. To evaluate flexural strength, resin specimens were made according to the different materials, powder/liquid ratio and processing methods. Flexural strength of the complete resin specimens (64mm$\times$10mm$\times$3.3mm) were measured by INSTRON 4467. (INSTRON, England) The data was analyzed by ANOVA, t-test and Tukey test. (p<.05 level of significance) Result: The results were as follows 1. There was no significant differences between master model and denture base for each group in overall dimensional changes. 2. Palatal area was more stable than flange or alveolar area in dimensional stability. but. there was no significant differences among each area. 3. Materials and power/liquid ratio had an effect on flexural strength. (P<.05) Especially materials was most effective. (P<.05) 4. Lucitone 199(powder/liquid ratio followed by manufacturer's direction) showed higher flexural strength than Vertex. Conclusion : Dimensional stability or flexural strength are affected by materials rather than packing techniques.

• Journal of the Korea Institute of Building Construction
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• v.16 no.5
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• pp.389-395
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• 2016

The evolution of electro-mechanical impedance (EMI) of the piezoelectricity (PZT) sensor was investigated to determine the setting times of cementitious materials in this study. The PZT sensor coated with non-conductive acrylic resin was embedded in cement paste before casting and the EMI signatures were continuously measured. Vicat needle test and semi-adiabatic calorimetry test were also conducted to justify the validity of EMI senssing technique in setting monitoring of cementitious materials. The results show that significant changes in EMI resonant peak magnitude and frequency during setting process were observed, and that the setting times determined by EMI sensing technique were relevant to the setting times measured by Vicat needle test and semi-adiabatic calorimetry test.

• Restorative Dentistry and Endodontics
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• v.43 no.1
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• pp.9.1-9.6
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• 2018

The objective of this case report is to introduce a simple technique for simultaneously taking a closed-mouth impression and functionally generated path (FGP) for a full coverage crown restoration. A monolithic zirconia crown was the restoration of choice. An alginate impression of the abutment tooth was taken to fabricate a custom-made closed-mouth impression tray covering the abutment tooth and the adjacent teeth. The tray had an FGP table and an abutment tray in cameo and intaglio surfaces, respectively. The impression was taken with silicone impression material after adjusting the abutment tray and inscribing the FGP using self-curing acrylic resins. Plaster casts were made from the impression, and a zirconia crown was fabricated. The crown was cemented to the abutment tooth with minimal adjustments. This simple technique resulted in a well-fitting crown that accounted for mandibular movements. Using the custom closed-mouth impression tray incorporating an FGP table simultaneously aids in fabricating an accurately fitting restoration that incorporates harmonious mandibular movements using a single impression capture.

• Journal of Fashion Business
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• v.8 no.5
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• pp.115-124
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• 2004

PTT(polytrimethylene terephthalate) is a thermoplastic that can be melt-spun into fibers and has extensive applications in carpets, textiles and apparel, engineering thermoplastics, nonwovens, and films or sheets. This polymer combines the good properties of nylon and polyester. Compared with other synthetic fibers such as nylon and acrylic, the PTT fibers feel softer, dye easier with vibrant colors, stretch and recover better. Moreover, the PTT fibers for carpets resist most stainings, clean better, and dry faster. The PTT was first patented in 1941, but it was not until the 1990's, when Shell Chemicals developed the practical method of producing PDO, the raw material for PTT. Many studies have been done including the retention of carpet texture using an image analysis technique, or compressional resilience of the carpet for long term use. In this study, PTT and nylon BCF carpets were compared in terms of the compressional properties including the resilience, using one of the KES system for repetitive measurements. The compression resilience(RC) values of the PTT BCF carpets far exceed those of nylon 6 BCF carpets. The RC values of the PTT BCF carpet(cut) specimens are $42{\sim}45%$ for 5 successive compression deformations, while those of the nylon BCF carpet specimens(cut) are $26{\sim}28%$. There is also a similar trend in the RC values for the other type of carpet which is the loop type. This resilience is one of the important factors of carpet usage evaluation.

• The Journal of Korean Academy of Prosthodontics
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• v.44 no.4
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• pp.466-476
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• 2006

Purpose : Colonization of denture soft lining materials by Candida albicans can result in clinical problem, and deterioration of the materials. This study aimed to compare the retention and penetration of C. albicans into four denture soft lining materials commonly used. Materials and methods : Four denture soft lining materials (Coe-comfort$^{(R)}$, Coe-soft$^{(R)}$, GC soft liner$^{(R)}$, and Tissue conditioner$^{(R)}$) discs were prepared to glass slide and dental stone. Adherence of yeast to surfaces was monitored after one hour incubation of standardized washed cell suspension with test disc surfaces. Adherent cells stained with acridine orange were counted fluorescence microscopy. Penetration of yeast into materials bonded with acrylic resin after 1, 2, 3,4, 5, 6 and 7 days incubation was observed through sections stained using acridine orange and estimated to quantitative analysis using radioisotope. Results : There was statistical significance in cell numbers between smooth and rough surfaces(p<0.05). Higher numbers of cells were observed on rough surfaces. There was statistical significance in adherent cell numbers into smooth and rough surfaces individually(p<0.05). According to the increase of incubation periods, the cells penetrated into denture soft lining materials were shown to increase. The differences among all kinds of soft liner were statistically significant(p<0.05),and the largest number of cells penetrated into soft liners was observed in the Coe-soft$^{(R)}$. Conclusion : Initial adherence and penetration of yeast into denture soft lining materials has been influenced by surface roughness and chemical composition of them. The selection of appropriate materials and their fabrication may promote clinical performance.

• The Journal of Korean Academy of Prosthodontics
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• v.43 no.5
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• pp.662-670
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• 2005

Statement of problem: Little is known about the effect of abutment preparation procedure on do-torque values in different implant platform and the relationship of final do-torque values with different implant platform size. Purpose: This study evaluated the effect of abutment preparation procedure on do-torque values in different implant platform and the relationship of final do-torque values with different implant platform size. Material and method: Six ITI implants (2 narrow-neck implants, 2 regular-neck implants, 2 wide-neck implants) and six Branemark implants (2 narrow platforms, 2 regular platforms, 2 wide platforms) were embedded in each acrylic resin block with epoxy resin. Eighteen $synOcta^(R)$ abutments (6 narrow-neck implant-abutments, 6 regular-neck implant-abutments, 6 wide-neck implant-abutments) and eighteen esthetic abutments (6 narrow platform-abutments, 6 regular platform-abutments, 6 wide platform-abutments) were tightened to each implant with digital torque gauge. Initial do-torque values were measured using digital torque gauge. After preparation of abutments, Final do-torque values were measured with digital torque gauge. Results and conclusion: 1. Screws loosening or abutments motion were not detected in all experimental group, but some scratches of implant-abutment joints were detected in all group 2. Reduction ratios of final do-torque values were greater than initial do-torque values in all measured group, except in narrow-neck implant-abutment group (p<0.05). 3. Reduction ratios of final do-torque values in wide-neck implant-abutment group were greater than regular-neck implant-abutment group (p<0.01). 4. The greatest standard deviation value was detected in wide platform group in both implant systems.

• Polymer(Korea)
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• v.26 no.1
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• pp.113-120
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• 2002

Electrostriction is the phenomenon that a material is strained due to Maxwell stress developed by the applied voltage. In many electrostrictive materials, especially polymeric elastomers can produce large deformation and force due to their low elastic modulus. In this study, polyurethanes and acrylic rubber with compliant electrodes were used as electrostrictive polymer(EP) actuator. Actuation characteristics of the EP actuators with different physical properties of dynamic modulus and dynamic dielectiric constant were analyzed under AC field. The classical laminate theory was also used to simulate the actuation process in relation to the geometry and the physical properties of the actuators.

• The Research Journal of the Costume Culture
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• v.25 no.3
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• pp.270-284
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• 2017

This study aimed to create 3D-printed insoles for flat-footed senior men using 3D systems. 3D systems are product-manufacturing systems that use 3-dimensional technologies like 3D scanning, 3D modeling, and 3D printing. This study used a 3D scanner (NexScan2), 3D CAD programs including Rapidform, AutoCAD, SolidWorks, Nauta+ compiling program, and a 3D printer. In order to create insoles for flat-footed senior men, we analyzed horizontal sections of 3D foot scans We selected 20 flat-footed and 20 normal-footed subjects. To make the 3D insole models, we sliced nine lines on the surface of the subjects' 3D foot scans, and plotted 144 points on the lines. We calculated the average of these 3D coordinates, then located this average within the 3D space of the AutoCAD program and created 3D sole models using the loft surface tools of the SolidWorks program. The sole models for flat feet differed from those of normal feet in the depth of the arch at the inner sideline and the big toe line. We placed the normal-footed sole model on a flat-footed sole model, and the combination of the two models resulted in the 3D insole for flat feet. We printed the 3D modeled insole using a 3D printer. The 3D printing material was an acrylic resin similar to rubber. This made the insole model flexible and wearable. This study utilized 3D systems to create 3D insoles for flat-footed seniors and this process can be applied to manufacture other items in the fashion industry as well.

• Solar Energy
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• v.10 no.2
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• pp.28-37
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• 1990

A study was conducted to investigate the feasibility of using a super-absorbent polymer made from a acrylic acid copolymer for a capsule-type ice storage system. In a simple pyrex-tube test, 25% of distilled water samples tested turned out not be frozen at all at $-12^{\circ}C$ and the average supercooling of the samples frozen was $9.8^{\circ}C$. With the addition of 0.5wt% super-absorbent polymer, however, the supercooling of the distilled water was dramatically reduced and more than 35% of samples tested did not show any supercooling. The heat transfer characteristics of a capsule-type ice storage unit was also investigated with a distilled water as the phase-change material. With the addition of 0.5wt% polymer, the supercooling of water was not observed at all and thus an overall heat transfer was enhanced. Based on these results, it was concluded that a super-absorbent polymer is a potential candidate as the nucleating agent for an ice-storage system.

• Imaging Science in Dentistry
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• v.40 no.2
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• pp.63-68
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• 2010

Purpose : To compare the CT numbers on 3 cone-beam CT (CBCT) images with those on multi-detector CT (MDCT) image using CT phantom and to develop linear regressive equations using CT numbers to material density for all the CT scanner each. Materials and Methods : Mini CT phantom comprised of five 1 inch thick cylindrical models with 1.125 inches diameter of materials with different densities (polyethylene, polystyrene, plastic water, nylon and acrylic) was used. It was scanned in 3 CBCTs (i-CAT, Alphard VEGA, Implagraphy SC) and 1 MDCT (Somatom Emotion). The images were saved as DICOM format and CT numbers were measured using OnDemand 3D. CT numbers obtained from CBCTs and MDCT images were compared and linear regression analysis was performed for the density, $\rho$ ($g/cm^3$), as the dependent variable in terms of the CT numbers obtained from CBCTs and MDCT images. Results : CT numbers on i-CAT and Implagraphy CBCT images were smaller than those on Somatom Emotion MDCT image (p<0.05). Linear relationship on a range of materials used for this study were $\rho$=0.001H+1.07 with $R^2$ value of 0.999 for Somatom Emotion, $\rho$=0.002H+1.09 with $R^2$ value of 0.991 for Alphard VEGA, $\rho$=0.001H+1.43 with $R^2$ value of 0.980 for i-CAT and $\rho$=0.001H+1.30 with $R^2$ value of 0.975 for Implagraphy. Conclusion: CT numbers on i-CAT and Implagraphy CBCT images were not same as those on Somatom Emotion MDCT image. The linear regressive equations to determine the density from the CT numbers with very high correlation coefficient were obtained on three CBCT and MDCT scan.