• 대한수학회보
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• 제38권1호
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• pp.197-203
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• 2001

We investigate change of the torsion tensor $S_\omega\mu^\nu$ induced by the conformal change in 7-dimensional g-unified field theory. These topics will be studied for the second class with the first category in 7-dimensional case.

• Korean Journal of Mathematics
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• 제7권2호
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• pp.199-205
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• 1999

We investigate change of the tensor $U^{\nu}_{{\lambda}{\mu}}$ induced by the conformal change in 5-dimensional $g$-unified field theory. These topics will be studied for the second class in 5-dimensional case.

• Korean Journal of Mathematics
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• 제5권2호
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• pp.141-149
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• 1997

We investigate chnage of the tensor $U^{\nu}{_{\lambda}{\mu}}$ induced by the conformal change in 6-dimensional $g$-unified field theory. These topics will be studied for the second class with the second category in 6-dimensional case.

• Restorative Dentistry and Endodontics
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• 제19권2호
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• pp.602-610
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• 1994

The purpose of this study was to measure the free flow of the unpolymerized resin by its weight for 10 minutes by one minute interval, and to measure the dimensional change of composite resins during the irradiation of visible light(Quich light VL-l Kuraray Japan) using visible leser displacement meter(LC-2210 Kerence Japan). The unpolymerized resin was cured by the visible light for 40 seconds, the dimensional change was measured at the begining of irradiation for 5 minutes. The results were as follows : 1. In free flow LFI was the largest, BLI was the smallest at $23^{\circ}C$ and CFP was the largest, and BL was the smallest at $37^{\circ}C$. 2. In dimensional change CFI, LFP, LEI and CFP was excessively contracted flow the begining of irradiation until 15 seconds but BLI and BL was excessively contracted until 30 seconds BL and BLI in dimensional change was much larger than LFI and CFP.

• 대한치과보철학회지
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• 제44권6호
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• pp.712-721
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• 2006

Statement of problem. Acrylic resin is most commonly used for denture bases. However, acrylic resin has week points of volumetric shrinkage during polymerization that reduces denture fit. The expandability of POSS (Polyhedral Oligomeric Silsesquioxane) containing polymer could be expected to reduce the polymerization shrinkage of denture bases and would increase the adaptability of the denture to the tissue. Purpose. The purpose of this study was to compare the dimensional stability in the conventional acrylic resin base, POSS-containing acrylic resin base, and metal bases. Materials and methods. Thirty six maxillary edentulous casts and dentures of different base were fabricated. Tooth movement and tissue contour change of denture after processing (resin curing, deflasking, decasting and finishing without polishing) and immersion in artificial saliva at $37^{\circ}C$ for 1 week and 4 weeks were measured using digital measuring microscope and threedimensional laser scanner. Results. The results were as follows: 1. The conventional resin group showed significant (p<0.01) dimensional change throughout the procedure (processing and immersion in artificial saliva). 2. After processing, the metal group and POSS resin group showed lower linear and 3-dimensional change than conventional resin group (p<0.01). 3. There was no statistically significant linear and 3-dimensional change after immersion for 1 week and 4 weeks in metal and POSS resin group. 4. In all groups, the midline and alveolar ridge crest area presented smaller 3-dimensional change compared with vestibule and posterior palatal seal area after processing and soaking in artificial saliva for 1 week and 4 weeks (p<0.01). Conclusion. In this study, a reinforced acrylic-based resin with POSS showed good dimensional stability.

• 대한치과보철학회지
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• 제34권3호
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• pp.574-592
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• 1996

This study investigated the time-dependent dimensional changes of elastomeric impression materials using holographic interferometry. Six commercial impression materials, Permlastic(polysulfide), Xantopren VL (condensation silicone), low and medium viscosity of Exafine, Provil (addition silicone), and Impregum(polyether), were selected. Steel plate was used as custom tray, and each impression specimen was 20 mm in width, 15 mm in length and 3 mm in thickness. Each impression material was evaluated at 30 minutes, 1, 2, 4, 6, 8 and 12 hours after setting using real-time holography. The results were as follow : 1. Xantopren VL and Permlastic showed relatively severe and continuous dimensional changes after setting. Low viscosity of Exafine, Provil, Impregum showed relatively slight dimensional changes with function of time and medium viscosity of Exafine showed almost no dimensional change from 2 hours after setting to 6 hours. 2. On initial dimensional changes within 1 hour, the amount of change in low viscosity of Exafine was the least and Xantopren VL was the largest. 3. On dimensional changes at 4 hours after setting, the amount of change in medium viscosity of Exafine was the least and tile change of Xantopren VL was the largest. 4. In overall dimensional stability during 12 hours, medium viscosity of Exafine was the most stable and Xantopren VL and Permlastic were least stable.

• 열처리공학회지
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• 제35권2호
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• pp.66-73
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• 2022

Partial-hardened hot stamping has been well known to be very effective to absorb more energy in automotive lateral crash. Hardness distribution and dimensional change after partial-hardened hot stamping have been studied to find out effect of thermal deformation of the heated hot stamping die on dimensional accuracy of automotive center pillar. Soft zone of commercial center pillar showed 275~345 in Vickers hardness, indicating bigger non-uniformity which resulted from thermal deformation of heated die. Dimensional changes in soft zone of the commercial center pillar measured by three dimensional scanner were much bigger than that in hard zone. It has been found that hot stamping die compensation considering thermal deformation in soft zone causes a significant decrease in hardness deviation in the soft zone, corresponding to 20 percent of commercial center pillar and subsequently leads to much higher dimensional accuracy.

• Maxillofacial Plastic and Reconstructive Surgery
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• 제27권6호
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• pp.552-558
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• 2005

Orthognathic surgery changes patient's mandibular position and environment of related anatomic structures. Many clinicians were interested in these changes and studied about this problem. However, most of them were based on two dimensional cephalogram. According to the development of image and computer system, it would be possible that the airway change is analyzed with three dimensional CT. So we tried to measure the volumetric change of airway and analyzed the relationship between the airway structure and volumetric change. Nineteen patients who experienced orthognathic surgery due to mandibular prognathism were analyzed with 3D CT data (preoperative and postoperative 6 months) and 2D lateral cephalometry. Volumetric change was measured and 3 dimensional change of related structure was assessed with simulation program ($V-works^{(R)}$, 4.0 Cybermed, Korea). Ten patients showed the decrease of airway volume change and nine showed the increase of airway volume change. Volumetric change was determined by dimensional change of mandible and hyoid bone. The dimensional positions of mandible and hyoid bone were the key factor for determining the airway change after surgery. Airway change is also predictable with the dimensional change of mandible and hyoid bone.

• 한국분말재료학회지
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• 제5권4호
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• pp.299-302
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• 1998

Dimensional accuracy is one of the most important issues in the production of sintered parts. The iron-copper-carbon system is commonly used alloys in sintered structural parts production. The dimensional control of these alloys, however, is not easy because of their complex sintering behavior. This study is an effort to clarify the influence of common factors on dimensional change of Fe-Cu-C sintered structural parts. We determined the effect of such various parameters as chemical composition, particle diameter, compact density, sintering temperature and sintering time on dimensional changes. Consequently, we obtained a useful formula to predict the final dimension in function of these parameters. The effect of typical impurities in copper powder on the dimensional change of sintered parts has also been described.

• 한국의상디자인학회지
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• 제22권4호
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• pp.93-104
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• 2020

This paper focuses on the spatial changes that create a three-dimensional or deep feeling on the surface of a scarf centering on the cube shape. Through this, consumers with various tastes were able to satisfy their image presentation. The cube form has simplicity and order and is likely to be used as a formative object. The cube shapes can be expressed in various forms through visual and perceptual spatial changes by presenting various shape changes based on the viewpoint of the two-dimensional silk surface, that is, by changing the eyes' position and orientation. Various visual theorists' discussions about cube-shaped visual changes were discussed. In addition, the three-dimensional spatial illusion caused by the shape and color of Victor Bazaarelli's cube was examined. The cube shape was printed silk surfaces to give a three-dimensional sense of space on a two-dimensional scarf design using the size change, the difference in the length of the line, and the color change. As such, the cube shape has infinite possibilities as a method that can express three-dimensional depth and space on the flat surface of a scarf. Therefore, it is hoped that this study will be applied to various aspects as the basic data for the scarf design that expresses the spatial changes in the form of cubes.