• The Journal of Advanced Prosthodontics
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• v.9 no.3
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• pp.232-237
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• 2017

Dentists often place post and core buildups on endodontically treated abutments for crown and bridge restorations. This article analyzes the bio-mechanical purposes, advantages and disadvantages of placing a core or a post and core in an endodontically treated tooth and reviews literature on post and core biomechanics. The author assesses the scientific rationale of the claim that the main purpose of a post is to retain a core, or the claim that posts weaken teeth. More likely, the main function of a post is to help prevent the abutment, on which a crown is cemented, from fracturing such that the abutment separates from the tooth root, at a fracture plane that is located approximately and theoretically at the level of the crown (or ferrule) margin. A post essentially improves the ferrule effect that is provided by the partial fixed denture prosthesis. This paper also explores the difference between bio-mechanical failures of crowns caused by lack of retention or excess taper, versus failures due to a sub-optimal ferrule effect in crown and bridge prostheses.

• Archives of Plastic Surgery
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• v.42 no.2
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• pp.164-172
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• 2015

Background The use of a tourniquet in hand surgery is generally accepted as necessary to create a clear visualization of the operative field. This study aims to determine the effectiveness of one-per-million tumescent solution (1:1,000,000 epinephrine concentration) in creating a bloodless operative field in post-burn hand deformity surgeries performed without a tourniquet. Methods This retrospective observational study was conducted on a series of 12 patients with post-burn hand deformities who underwent surgery between February 2013 and January 2014. A total of 29 operative fields were recorded. The one-per-million tumescent solution was used for hemostatis instead of a tourniquet. The clarity of the operative field, volume of solution injected, duration of surgery, scar thickness and density, and functional outcomes at least three months after the surgery were observed. The relationship of scar thickness and density with the clarity of the operative field was analyzed with the chi-square test. Results Of the 29 operative fields in which the one-per-million tumescent technique was used, 48.2% were totally bloodless, 44.8% had minimal bleeding, and 6.9% had an acceptable level of bleeding. Both scar thickness and density were shown to have a significant relationship with operative field clarity (P<0.05). Conclusions The one-per-million tumescent technique is effective in facilitating post-burn hand deformity surgeries involving meticulous, multiple, and lengthy procedures by creating a relatively clear operative field without the use of a tourniquet. Although scar thickness and density are associated with the clarity of the operative field, this technique can be considered safe and effective in creating a clear operative field.

• Architectural research
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• v.8 no.1
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• pp.47-56
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• 2006

In this research, the analysis of post-buckling behavior of tapered columns has been performed under a combined load of uniformly distributed axial load along the length and concentric axial load at free end by solving the nonlinear differential equation with the differential transformation technique. The buckling load at various slopes at free end of column is calculated and the results of the analysis using the differential transformation technique is verified with those of previous studies. It is also shown through the results that the buckling load of sinusoidal tapered columns is largest, the linear is second largest, and the parabolic is small in the all ranges of slopes at free end and the deflection of parabolic tapered columns in the x coordinates is largest, the sinusoidal is second largest, and the linear is smallest in the range of slope 0 to 140 degrees at free end. However, when the range of the slope is 160 to 176 degrees at the free end, the deflection of sinusoidal tapered columns in the x coordinates is largest, the linear is second largest, and the parabolic is smallest. In addition, for the linear tapered column, the buckling load increases along with the flexural stiffness ratio. Also, for the parabolic and the sinusoidal tapered column, the buckling loads increase and decrease as the flexural ratios increase in the range of flexural stiffness ratio n = 1.0 to n = 2.0. Through this research, it is verified that the differential transformation technique can be applied to solve the nonlinear differential equation problems, such as analysis of post-buckling behavior of tapered columns. It is also expected that the differential transformation technique apply to various more complicated problems in future.

• The Journal of Korean Physical Therapy
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• v.21 no.3
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• pp.17-24
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• 2009

Purpose: The purpose of this study was to investigate the effects of a combination of isotonic (CI) technique on the balance, muscle fatigue and muscle activities of the quadriceps muscle in the paretic leg of hemiplegic patients. Method: All the subjects received a combined isotonic technique of proprioceptive neuromuscular facilitation (PNF) for about 30 minutes 3 times per week for 6 weeks. The root mean square (RMS) and mid frequency (MF) were recorded by surface electromyography (EMG)(EMG/EP system, OXFORD Medelec, UK) during maximal voluntary isometric contractions (MVIC). The balance ability was measured by a balance system (BIODEX, USA). Result: The RMS of the quadriceps muscle at post-treatment was significantly increased compared to that at pretreatment (p<0.05). Yet there was no significant difference among the three muscles. There were no significant difference in the MF of the vastus lateralis and rectus femoris between pre- and post-treatment, but the MF of the vastus medialis was significantly decreased (p<0.05). There was a significant difference in the vastus medialis and lateralis between pre- and post-treatment (p<0.05). Moreover, the overall stability index at post-treatment was significantly decreased compared to that at pre-treatment (p<0.05). But there was no significant difference between the anterior/posterior and medial/lateral stability indexes. Conclusion: The results of this study indicated that a CI technique of PNF had an effect to improve the balance and muscle activity in hemiplegic patients.

• Journal of the Korean Society of Physical Medicine
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• v.11 no.4
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• pp.115-125
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• 2016

PURPOSE: This study aimed to compare the effects of lumbar stabilization exercise with those of the neurodynamic technique on low back pain in patients with lumbar instability. METHODS: The subjects included those with more than three tests with positive results for lumbar instability and those with a positive sign during the neurodynamic test, all of whom had low back pain. For the lumbar stabilization exercise group (n=15), lumbar stabilization exercise was performed using a sling system, while the neurodynamic technique group (n=15) performed the neurodynamic technique. The intervention was performed 5 days a week for 4 weeks. All measurement of each subject were measure at pre-intervention and post-intervention (after 4 weeks). SPSS/PC ver. 18.0 program was used to compile results. RESULTS: There was no significant difference in general characteristics of subjects between both groups (p>.05). Assessed items included the visual analog scale score (VAS), Korean version of the Oswestry Disability Index (KODI), lumbar instability test positive response counter (LIC) and Fear-Avoidance Beliefs Questionnaire score (FABQ), and a significant reduction was observed post-intervention compared to pre-intervention values in both groups (p<.01). Other assessed items such as trunk flexibility and lumbar extensor endurance and lumbar flexor endurance were significantly increased post-intervention in both groups compared to pre-intervention values (p<.01). There was no significant difference in all parameters between both groups (p>.05). CONCLUSION: Our results indicate that the neurodynamic technique may be useful for improving low back pain in patients with lumbar instability.

• JSTS:Journal of Semiconductor Technology and Science
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• v.8 no.4
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• pp.283-288
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• 2008

A post-linearization technique for the differrential CMOS LNA is presented. The proposed method uses an additional cross-coupled common-source FET pair to cancel out the third-order intermodulation ($IM_3$) current of the main differential amplifier. This technique is applied to enhance the linearity of CMOS LNA using $0.18-{\mu}m$ technology. The LNA achieved +10.2 dBm IIP3 with 13.7 dB gain and 1.68 dB NF at 2 GHz consuming 11.8 mA from a 1.8-V supply. It shows IIP3 improvement by 6.6 dB over the conventional cascode LNA without the linearizing circuit.

• Restorative Dentistry and Endodontics
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• v.39 no.4
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• pp.324-328
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• 2014

Although fiber-reinforced posts have been widely used, they sometimes fail to obtain sufficient retention because of an extremely large canal space. To address this, several techniques have been introduced including relining of the fiber-reinforced posts. Here, we used a relined glass-fiber post to increase retention and fitness to the root canal in a crown reattachment case. The relining procedure was performed by using an indirect method on the working cast. This case also highlights the esthetic concerns regarding dehydration of the attached crown fragment.

• Computers and Concrete
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• v.12 no.3
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• pp.351-375
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• 2013

Post-punching resistance of a flat slab can help redistribute the gravity loads and resist progressive collapse of a structure following initial damage. One important difficulty with accounting for the post-punching strength of a slab is the discontinuity that develops following punching shear. A numerical simulation technique is proposed here to model and evaluate post-punching resistance of flat slabs. It is demonstrated that the simulation results of punching shear and post-punching response of the model of a slab on a single column are in good agreement with corresponding experimental data. It is also shown that progressive collapse due to a column removal (explosion) can lead to punching failure over an adjacent column. Such failure can propagate throughout the structure leading to the progressive collapse of the structure. Through post-punching modeling of the slab and accounting for the associated discontinuity, it is also demonstrated that the presence of an adequate amount of integrity reinforcement can provide an alternative load path and help resist progressive collapse.

• Journal of the Society of Naval Architects of Korea
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• v.44 no.2 s.152
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• pp.93-100
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• 2007

Post swirl stator is an energy saving device to recover rotational energy of the propeller. To optimize the performance of post swirl stator in container vessels, computational fluid dynamics using body force method was introduced. A commercial code Fluent was used in conjunction with body force distributed on the surface of actuator disk which is located in the propeller plane to optimize pitch angle of the post swirl stator blade. This study showed that CFD is an important tool to simulate flow behind ship with propeller, rudder and post swirl stator.

• Steel and Composite Structures
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• v.34 no.2
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• pp.289-297
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• 2020

In the present research post-buckling of a cut out plate reinforced through carbon nanotubes (CNTs) resting on an elastic foundation is studied. Material characteristics of CNTs are hypothesized to be altered within thickness orientation which are calculated according to Mori-Tanaka model. For modeling the system mathematically, first order shear deformation theory (FSDT) is applied and using energy procedure, the governing equations can be derived. With respect to Rayleigh-Ritz procedure as well as Newton-Raphson iterative scheme, the motion equations are solved and therefore, post-buckling behavior of structure will be tracked. Diverse parameters as well as their reactions on post-buckling paths focusing cut out measurement, CNT's volume fraction and agglomeration, dimension of plate and an elastic foundation are investigated. It is revealed that presence of a square cut out can affect negatively post-buckling behavior of structure. Moreover, adding nanocompsits in the matrix leads to enhancement of post-buckling response of system.