• The korean journal of orthodontics
• /
• v.51 no.3
• /
• pp.179-188
• /
• 2021

Objective: To evaluate the overall treatment effects in terms of the amount of uprighting with changes in the sagittal and vertical positions of mandibular molars after applying an orthodontic miniplate with a nickel-titanium (NiTi) reverse curve arch wire (biocreative reverse curve [BRC] system). Methods: A total of 30 female patients (mean age, 25.99 ± 8.96 years) were treated with the BRC system (mean BRC time, 10.3 ± 4.07 months). An I-shaped C-tube miniplate (Jin Biomed) was placed at the labial aspect for the alveolar bone of the mandibular incisors. A 0.017 × 0.025-inch NiTi reverse curve arch wire was engaged at the C-tube mini-plate anteriorly and the first and second premolars and molars posteriorly in the mandibular arch. Pre- and post-BRC lateral cephalograms were analyzed. A paired t-test was used to analyze the treatment effects of BRC. Results: The mandibular second molars were intrusively uprighted successfully by the BRC system. Distal uprighting with a controlled vertical dimension was noted on the first molars when they remained engaged in the BRC and the distal ends of the arch wire were laid on the second molars. The mandibular first and second premolars showed a slight extrusion. The changes in the mandibular incisors were unremarkable, while the mandibular molar angulation improved significantly. The lower occlusal plane rotated counterclockwise (MP-LOP: 1.13° ± 2.60°). Conclusions: The BRC system can provide very effective molar uprighting without compromising the position of the mandibular anterior teeth.

• The korean journal of orthodontics
• /
• v.34 no.3 s.104
• /
• pp.219-227
• /
• 2004

The purpose of this study was to evaluate the spatial changes of mesial-in rotated maxillary molar and opposite anchor tooth during derotation by the precision transpalatal arch (TPA) with the use of a new typodont simulation system, the Calorific machine system, which was designed to observe the whole process of tooth movement. The maxillary right first molar was used for the anchor tooth and the maxillary left first molar was used for the mesial-in rotated tooth, and the angle of rotation was increased to 20,40, and 60. A passive precision TPA was fabricated and then activated by bending the left arm to 20, 40, and 60. Each experiment was repeated five times under the same conditions and analyzed by ANOVA and Tucky's Studentized Range (HSD) test. In the occlusal plane, when the bending angle of precision TPA was increased, the mesiobuccal cusp of the rotated molar moved more buccally (p<0.001) and less distally (p<0.001) while the distolingual cusp moved in the mesiopalatal direction. In the sagittal plane, the palatal roots of the derotated molar moved mesially (p<0.001). In the traverse plane, the derotated molar showed slight extrusion (p<0.001). The upper right first molar, which was used as an anchor tooth, showed clinically insignificant movement across all three planes.

• Membrane Journal
• /
• v.22 no.1
• /
• pp.8-15
• /
• 2012

Tubular $Ba_{0.5}Sr_{0.5}Co_{0.8}Fe_{0.2}O_{3-{\delta}}$ membranes with $La_{0.6}Sr_{0.4}Ti_{0.3}Fe_{0.7}O_{3-{\delta}}$ porous coating layer were prepared by extrusion and dip coating technique. XRD and SEM result showed the tubular membrane possessed the perovskite structure and porouscoating layer (thickness= about $2{\mu}m$) in surface. The oxygen permeation test was measured at condition of ambient air (feed side) and vacuum (permeate side) in the temperature range from 750 to $950^{\circ}C$. The oxygen permeation flux of $Ba_{0.5}Sr_{0.5}Co_{0.8}Fe_{0.2}O_{3-{\delta}}$ tubular membrane with $La_{0.6}Sr_{0.4}Ti_{0.3}Fe_{0.7}O_{3-{\delta}}$ porous coating layer reached maximum $3.2mL/min{\cdot}cm^2$ at $950^{\circ}C$ and was higher than non-coated $Ba_{0.5}Sr_{0.5}Co_{0.8}Fe_{0.2}O_{3-{\delta}}$ tubular membrane. Long-term stability test result indicated that the oxygen permeation flux was quite stable during the 11 day.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.27 no.1
• /
• pp.71-77
• /
• 2023

This study aims to investigate the structural performance of hollow-core slab (HCS) memebers with 400 mm thickness. To this end, a total of four HCS specimens were fabricated based on the individual mold method to provide shear reinforcement, unlike the extrusion method. The key variables were chosen as the presence of topping concrete, core-filling concrete, and shear reinforcements. The crack patterns and load-displacement responses of the test specimens were analyzed in detail. Test results showed that inclined shear cracking occurred all the specimens, and that the specimen with shear reinforcement on the web of HCS unit had higher strength and ductility than the specimen without shear reinforcement. In particular, shear reinforcements placed on the web of HCS unit effectively resisted not only to vertical shear force but also to horizontal shear force between the interface of HCS unit and topping concrete. In addition, it was discovered that the method in which shear reinforcements are placed on the web of HCS unit is more effective in improving structural performance than core-filling method.

• Journal of Powder Materials
• /
• v.9 no.6
• /
• pp.394-408
• /
• 2002

Nanostructured high strength metastable Al-, Mg- and Ti-based alloys containing different amorphous, quasicrystalline and nanocrystalline phases are synthesized by non-equilibrium processing techniques. Such alloys can be prepared by quenching from the melt or by powder metallurgy techniques. This paper focuses on one hand on mechanically alloyed and ball milled powders containing different volume fractions of amorphous or nano-(quasi)crystalline phases, consolidated bulk specimens and, on the other hand. on cast specimens containing different constituent phases with different length-scale. As one example. $Mg_{55}Y_{15}Cu_{30}$- based metallic glass matrix composites are produced by mechanical alloying of elemental powder mixtures containing up to 30 vol.% $Y_2O_3$ particles. The comparison with the particle-free metallic glass reveals that the nanosized second phase oxide particles do not significantly affect the glass-forming ability upon mechanical alloying despite some limited particle dissolution. A supercooled liquid region with an extension of about 50 K can be maintained in the presence of the oxides. The distinct viscosity decrease in the supercooled liquid regime allows to consolidate the powders into bulk samples by uniaxial hot pressing. The $Y_2O_3$ additions increase the mechanical strength of the composites compared to the $Mg_{55}Y_{15}Cu_{30}$ metallic glass. The second example deals with Al-Mn-Ce and Al-Cu-Fe composites with quasicrystalline particles as reinforcements, which are prepared by quenching from the melt and by powder metallurgy. $Al_{98-x}Mn_xCe_2$ (x =5,6,7) melt-spun ribbons containing a major quasicrystalline phase coexisting with an Al-matrix on a nanometer scale are pulverized by ball milling. The powders are consolidated by hot extrusion. Grain growth during consolidation causes the formation of a micrometer-scale microstructure. Mechanical alloying of $Al_{63}Cu_{25}Fe_{12}$ leads to single-phase quasicrystalline powders. which are blended with different volume fractions of pure Al-powder and hot extruded forming $Al_{100-x}$$(Al_{0.63}Cu_{0.25}Fe_{0.12})_x$ (x = 40,50,60,80) micrometer-scale composites. Compression test data reveal a high yield strength of ${\sigma}_y{\geq}$700 MPa and a ductility of ${\varepsilon}_{pl}{\geq}$5% for than the Al-Mn-Ce bulk samples. The strength level of the Al-Cu-Fe alloys is ${\sigma}_y{\leq}$550 MPa significantly lower. By the addition of different amounts of aluminum, the mechanical properties can be tuned to a wide range. Finally, a bulk metallic glass-forming Ti-Cu-Ni-Sn alloy with in situ formed composite microstructure prepared by both centrifugal and injection casting presents more than 6% plastic strain under compressive stress at room temperature. The in situ formed composite contains dendritic hcp Ti solid solution precipitates and a few $Ti_3Sn,\;{\beta}$-(Cu, Sn) grains dispersed in a glassy matrix. The composite micro- structure can avoid the development of the highly localized shear bands typical for the room temperature defor-mation of monolithic glasses. Instead, widely developed shear bands with evident protuberance are observed. resulting in significant yielding and homogeneous plastic deformation over the entire sample.

• Restorative Dentistry and Endodontics
• /
• v.36 no.5
• /
• pp.377-384
• /
• 2011

Objectives: The purpose of this study was to observe the change in the viscoelastic properties of thermoplasticized injectable root canal filling materials as a function of temperature and to compare the handling characteristics of these materials. Materials and Methods: Three commercial gutta perchas and Resilon (Pentron Clinical Technologies) in a pellet form were heated in the Obtura-II system (Obtura Spartan) at $140^{\circ}C$ and $200^{\circ}C$, and the extrusion temperature of the thermoplasticized materials was measured. The viscoelastic properties of the materials as a function of temperature were evaluated using a rheometer. The elastic modulus G', viscous modulus G", loss tangent tan${\delta}$, and complex viscosity ${\eta}^*$ were determined. The phase transition temperature was determined by both the rheometer and a differential scanning calorimeter (DSC). The consistency of the materials was compared under compacting pressure at $60^{\circ}C$ and $40^{\circ}C$ by a squeeze test. Results: The three gutta perchas had dissimilar profiles in viscoelastic properties with varying temperature. The phase transition of softened materials into solidification occurred at $40^{\circ}C$ to $50^{\circ}C$, and the onset temperatures obtained by a rheometer and a DSC were similar to each other. The onset temperature of phase transition and the consistency upon compaction pressure were different among the materials (p < 0.05). Resilon had a rheologically similar pattern to the gutta perchas, and was featured between high and low-flow gutta perchas. Conclusions: The rheological characteristics of the thermoplasticized root canal filling materials changed under a cooling process. The dissimilar viscoelastic properties among the materials require different handling characteristics during an injecting and compacting procedure.

• Korean Journal of Food Science and Technology
• /
• v.34 no.2
• /
• pp.186-193
• /
• 2002

This study was conducted to enhance the protein quality of wheat flour extrudates with the addition of fish sauce by-products and dried biji. The experimental design was used to determine the optimum ratio of each ingredient. The compositional and functional properties of test extrudate were measured, and these values were applied to the mathematical models. A canonical form and trace plot showed that the influence of each ingredient on the mixture final product. Protein content of extrudate was increased by the addition of the dried biji, and bending failure stress of extrudate became hardened due to interaction effects between dried biji and pacific sand lance sauce by-product. Also, the addition of dried biji decreased ash and salt contents. An optimum formulation was obtained as 15.83 : 44.17 : 40% with numerical and 15.74 : 44.26 : 26.40% with graphical method (pacific sand lance sauce by-product : dried biji : wheat flour). Based on the growth performance, feed conversion efficiency was slightly lower than control group, but the protein content in feed extrudate increased to a large extent compared to that mixed with wet biji.

• Resources Recycling
• /
• v.24 no.2
• /
• pp.13-22
• /
• 2015

$CO_2$ emitted from building materials and construction materials industry reaches about 67 million tons, which occupy about 30 % of $CO_2$ emitted from the construction field. Controls on the use of consumed fossil fuels and reduction of emission gases are essential for the reduction of $CO_2$ in the construction area as we reduce the second and third curing to emit $CO_2$ in the construction materials industry. Accordingly, this study applied the low energy curing admixture (hereinafter "LA") to the extruded panels to observe the physical properties, depending on the mixing amount of fiber, type of fiber and mixing ratio of fiber. The type of fiber did not appear to be a main factor to affect strength, while the LA mixing ratio and mixing amount of fiber appeared to be major factors to affect strength. Especially, the highest strength was developed when the LA mixing ratio was 40%, whereas the test object with the mixing ratio of 50% resulted in the decrease of strength. In addition, it appeared that the mixing ratio of fiber greatly affected flexural strength and strength increased as the mixing ratio increased.

• Journal of Oral Medicine and Pain
• /
• v.36 no.3
• /
• pp.199-205
• /
• 2011

During root canal treatment, overinstrumentation with hand or mechanically driven files can perforate the mandibular canal, allowing the extrusion of endodontic sealers, dressing agents, and irrigant solutions out of the tooth and into the canal. The patient may report symptoms such as pain, hyperesthesia, hypoesthesia, anesthesia, dysesthesia and paresthesia. Such problems must be resolved as quickly as possible to avoid irreversible sequelae caused by certain neurotoxic materials that form part of endodontic sealants. Although there have been no controlled trials of treatment protocols involving endodontically related injuries to the inferior alveolar nerve, the normal therapeutic sequence for this complication is the control of pain and inflammation and, whenever possible, the surgical elimination of the cause. However, total resolution of pain and reduction in or disappearance of paraesthesia after a non-surgical management have been reported. Antiepileptic drugs such as gabapentin or pregabalin have been used for the treatment of neuropathic pain. This article describes a case of inferior alveolar nerve(IAN) damage after endodontic treatment of a mandibular right second molar and the treatment with non-surgical approach using prednisone and gabapentin medication, monitoring the patient's condition with clinical neurosensory examination and current perception threshold test(Neurometer).

• Korean Journal of Food Science and Technology
• /
• v.34 no.3
• /
• pp.437-443
• /
• 2002

Using agar and gelatin as wall materials, onion oil was microencapsulated using the extrusion spraying technology. A sensitive methodology was developed for quantitative determination of the microencapsulation yield through ethyl acetate extraction and gas chromatographic analyses. Optimal conditions for the microencapsulation process consisting of the ratio of [core material, Cm] to [wall material, Wm] ($X_1$), temperature of dispersion fluid ($X_2$), detergent concentration in dispersion fluid ($X_3$), and concentration of emulsifier $(X_4)$ were determined using response surface methodology. The regression model equation for the yield of microencapsulation (Y, %) of onion oil could be predicted as $Y\;=\;97.028571-0.775000\;(X_1)-0.746726\;(X_1){\cdot}(X_1)\;-\;1.100000\;(X_3){\cdot}(X_2)$. The optimal conditions for the microencapsulation of the onion oil were determined as the ratio of [core material] to [wall material] of 4.5 : 5.5 (w/w), the temperature of dispersion fluid of $17.1^{\circ}C$ detergent concentration in dispersion fluid of 0.03%, and the concentration of emulsifier of 0.42%. Results revealed the most stable microcapsule of onion oil could be formed with the highest yield of microencapsulation (more than 95%) under optimal conditions.