• Journal of Dental Rehabilitation and Applied Science
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• v.31 no.4
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• pp.316-328
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• 2015

Purpose: The objects of this study was to evaluate the accuracy of the dental stone casts made from alginate impressions according to storage condition and stone pouring time. Materials and Methods: Each of upper and lower impressions of dental model was taken. The dental stone models were made immediately, 10, 30, 60, 180, 360 minutes after the impressions were taken at each storage condition. 3D models were constructed by scanning the stone model using 3D laser scanner. With Reference points, positioned on digital models, linear measurements of the dimensional change were compared by 3D metrology software, 3D average models were made and superimposition to identify the specific site of dimensional change and to measure surface deviation (mm). Results: Dental stone models which were made immediately after taking the impression showed the smallest linear dimensional change. As the stone pouring time was prolonged, the linear dimensional change was increased. More than 180 minutes after impression taking, linear dimensional change and surface distortion increased in the posterior molar region, regardless of the storage condition. Conclusion: For the optimum accuracy of the dental stone casts, alginate impression should be poured as soon as possible. If there were a need for storing, a humidor with 100% relative humidity must be used and be stored less than 180 minutes to fabricate the accurate dental model.

• Journal of the Korean Society of Clothing and Textiles
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• v.29 no.12 s.148
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• pp.1619-1626
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• 2005

The durability of a stretch fabric is mainly related to the change in the dimension and mechanical properties of elastomeric fibers during wearing and washing. In this study, we examined the effects of washing temperature, presoaking time and the number of washing cycles on the change in length, tenacity, elongation at break, and permanent elongation after six repeated cycles of $100\%$ extension and relaxation of spandex yams with varying fineness and with a different rate of extension during heat-set. The spandex yarns continued to shrink as the wash temperature and the number of wash cycles increased. In addition, the finer spandex yams decreased in length more than the thicker yams. The increase in temperature and presoaking time tended to cause a slight decrease in the tenacity and elongation at break of the spandex yarns. Permanent elongation of the spandex yams also increased as the temperature, presoaking time and the number of washing cycles increased. Moreover, an extended presoaking time followed by washing at $40\%$ like repeated washing cycles showed the great increase in the permanent elongation of spandex yams. The thinner spandex yin had a better elasticity than the thicker one, since the former had a lower permanent elongation percentage than the latter. Based on the DSC thermograms, the melting points of the spandex yarns after washing were almost the same as those of the spandex yarns before washing.

• Composites Research
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• v.12 no.3
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• pp.55-65
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• 1999

In this paper, the thermal buckling and postbuckling behaviour of composite beam with embedded shape memory alloy (SMA) wires are investigated experimentally and analytically. The results of thermal buckling tests on uniformly heated, clamped, composite beam embedded with SMA wire actuators are presented and discussed in consideration of geometric imperfections, slenderness ratio of beam and embedding position of SMA wire actuators. The shape recovery force can reduce the thermal expansion of composite laminated beam, which result in increment of the critical buckling temperature and reduction of the lateral deflection of postbuckling behaviours. It is presented quantitatively on the temperature-load-deflection behaviour records how the shape recovery force affects the thermal buckling. The cross tangential method is suggested to calculate the critical buckling temperature on the temperature-deflection plot. Based on the experimental analysis, the new formula is also proposed to describe the critical buckling temperature of a laminated composite beam with embedded SMA wire actuators.

• The Journal of the Korean bone and joint tumor society
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• v.18 no.2
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• pp.83-88
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• 2012

We reviewed the clinical features of 2 patients who underwent surgery for subungal exostosis, focusing on postoperative deformity of the nail. The lesion destroyed the nail bed and was excised with a direct approach. then thin split-thickness sterile matrix graft was done after excision of the tumor because the defect of the nail bed was large. Good postoperative appearance of the nail was obtained by thin split-thickness sterile matrix graft. The use of thin split-thickness sterile matrix graft for the replacement of a nail bed defect can regain a smooth, adherent, and normal-looking nail and avoid donor-site morbidity. Thin split-thickness toe-nail bed graft is a good choice for the prevention of postoperative deformity.

• Journal of the Korean Society of Radiology
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• v.17 no.2
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• pp.223-230
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• 2023

This study attempted to concider the morphological change of red blood cells after whole body irradiation. Blood samples used red blood cells of white mice and mouse after irradiation. Transmission electron microscope observation results, Anisocytosis was observed in red blood cells 20 days after 5 Gy irradiation. Triangle and tetrapod were observed for small red blood cell types. Poikilocytosis, sickle-shaped Drepanocyte, and Acantocyte were observed in general-sized red blood cells. Schizocyte was observed in red blood cells 20 days after 7 Gy irradiation. Scanning electron microscope observation results, Dacryocyte was observed with microcytes. It was also confirmed that red blood cells were get tangled with each other. In addition, polygonal shapes and half-moon shapes were also observed. In conclusion, it is judged that the modified form of pathological study is more important than the numerical change in the study of red blood cells by radiation exposure. In conclusion, it was confirmed that modified morphological studies are more important than numerical changes in the study of red blood cells by radiation exposure.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.3C
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• pp.209-218
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• 2006

In this study, stress and deformation of CFRD during its construction and impounding were analyzed and compared with its monitoring results. Moreover, deformation characteristics of CFRD after impounding were evaluated based on the settlement monitoring records of total 23 domestic and foreign CFRDs during construction and impounding. The investigation on the behavior of CFRD indicated that the influence of impounding on its stability was minimal although slight increases in vertical and horizontal stresses and strains were observed. Also, one method was proposed to predict a crest settlement from multi-layer settlements by applying the best fit method. It is expected that the results of this study would provide practical information for the design, construction, and management of CFRD.

• The korean journal of orthodontics
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• v.39 no.5
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• pp.310-319
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• 2009

Objective: NiTi closed coil springs were reported to have relatively constant unloading forces. However, the characteristics of NiTi closed coil springs from various manufacturers have not been elucidated. The purpose of this study was to compare load-deflection characteristics of various NiTi closed coil springs and to find out the optimal range of extension. Methods: Seven kinds of NiTi closed coil springs from five manufacturers were tested. Load deflection curves were obtained at extension ranges from 2 mm to 30 mm. Also, springs were kept extended during a 4 week period, and then load deflection curves were obtained again. Results: Sentalloy (Tomy) and Jinsung blue (Jinsung) showed superelasticity in every extension ranges tested and showed plastic deformation of less than 1 mm. Ni-Ti (Ormco) showed superelasticity only after the springs were extended at or more than 10 mm, thereby meaning that clinicians should extend these springs at or more than 10 mm to utilize the superelasticity. Orthonol (RMO) and Nitanium (Ortho Organizers) did not show superelasticity. After 4 weeks of extension, all springs showed plastic deformation less than 1 mm when the extension was at or under 25 mm. Conclusions: The superelastic behavior of NiTi closed springs were different among various NiTi spring products, and some NiTi closed springs failed to show superelasticity.

• Journal of dental hygiene science
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• v.12 no.6
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• pp.660-665
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• 2012

The purpose of this study was to use basic data of dental hygiene curriculum by comparing the rolling method and modified stillman method. Plaque measurement method, Q-ray examination of the clinical utilization value shall review. True experimental design is randomized controlled trial to the intervention group and the control group. Measurements are plaque control record (PCR; O'Leary index) measurements and Quantitative Light induced fluorescnece Digital (QLFD) shooting as a pre-test was conducted. Intervention group is modified stillman method, control group is rolling method. Intervention after 5 weeks, PCR measurement and QLFD shooting was carried out as a post-test. Rolling method and modified stillman method plaque reduction did not differ. Intervention before and after the results of the comparison showed reduced plaque score after brushing law education. Also, Plaque reduction differences were more pronounced modified stillman method than rolling method. PCR and QLFD values of the correlation was not confirmed but SPS Score and the lower value of the ${\Delta}R$ value of the correlation. Plaque of maturity tooth that are not observed visually.

• Microbiology and Biotechnology Letters
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• v.26 no.3
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• pp.264-268
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• 1998

Many enzymes catalyze a primary reaction and/or secondary reaction. Dextransucrase usually synthesizes dextran from sucrose as a primary reaction. The secondary reaction of dextransucrase is the transfer of glucose from sucrose to carbohydrate accepters. We have reacted dextransucrase from Leuconostoc mesenteroides B-742CB with sucrose and pullulan as an acceptor under different reaction conditions; various concentrations of pullulan, enzyme, sucrose and different pHs and temperatures of reaction digests. The yield of modified pullulan was 57%(<${\pm}$5%) of theoretical under the reaction condition of pH 5.2, temperature 28$^{\circ}C$, 0.37% of pullulan, and 0.l U/$m\ell$ of dextransucrase. Modified products were more resistant against the hydrolysis of pullulanase and endo-dextranase than those of native pullulan. The positions of glucose substitution in the modified products were determined by methylation followed by acid hydrolysis and analyzed by TLC. The products were modified by the addition of glucose to the position of C3, C4, C6 free hydroxyl group of glucose residues in the pullulan.

• Proceedings of the Materials Research Society of Korea Conference
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• 2003.11a
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• pp.55-55
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• 2003

Ferroelectric 물질은 고유전성, 자발분극과 전기장에 따른 유전상수의 변화 등의 특성을 가지고 있으므로 많은 연구가 진행중이다. 이러한 ferroelectric 물질의 유전 특성에 미치는 요소로는 물질의 조성비, 박막의 스트레스, 결정성 등이 있다. 특히 스트레스에 대한 연구가 활발히 진행중이다. 본 연구에서 산화물 인공격자를 이용하여 단일박막에서 얻을 수 없는 격자변형도를 얻어 격자 변형이 박막의 유전특성에 미치는 영향을 연구하였다. BaTiO$_3$ (BTO)/SrTiO$_3$ (STO) 산화물 인공격자를 Pulsed laser deposition (PLD)법으로 (La,Sr)CoO$_3$ 전극이 코팅된 MGO (100) 단결정 기판위에 증착시켰다. 적층 주기에 변화를 주어 BTO와 STO 각각 1.01~1.095와 0.925 ~ 1.003의 단일 막에서는 얻을 수 없는 격자 변형도를 얻었다. 이 실험적 데이터를 기초로 하여 density functional theory (DFT)라고 불리는 범함수밀도론를 기초한 제일원리적 계산 방법을 통하여 격자 변형된 SrTiO$_3$의 구조적, 전기적 특성을 계산하였다. SrTiO$_3$와 BaTiO$_3$ 격자의 안정성을 분석하기 위하여 Vienna Ab-intio Simulation Package (VASP) code가 사용되었다. SrTiO$_3$와 BaTiO$_3$ 산화물 격자의 안정성 분석 후, frozen-phonon 계산 방법을 사용하여 zone-centered optical phonon mode가 계산되었으며, mode effective charge는 Berry-phase polarization 으로부터 얻어졌다. SrTiO$_3$ 격자가 격자변형이 일어나지 않은 상태로부터 c/a= 0.985로 격자 변형 이 일어남에 따라 optical phonon mode는 점차 hardening되었다. BaTiO$_3$ 격자의 경우 SrTiO$_3$ 격자와는 달리 격자 변형이 1.01~1.023으로 진행됨에 따라 optical phonon mode의 증가를 가져왔으나 Born effective charge의 증가하였으며, 더 이상 격자 변형이 진행됨에 따라 optical phonon mode의 감소를 가져왔으나 Born effective charge의 증가 유전상수는 증가했다. 격자 변형이 SrTiO$_3$ 와 BaTiO$_3$ 산화물 격자의 optical phonon mode와 Born effective charge에 크게 영향을 미쳤다.