• Restorative Dentistry and Endodontics
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• 제45권4호
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• pp.47.1-47.11
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• 2020

Objectives: The aim of this study was to assess the physicochemical properties, cytotoxicity and penetration into dentinal tubules of ChlorCid^TM Surf (3% sodium hypochlorite [NaOCl] with surfactant) in comparison to ChlorCid^TM (3% NaOCl without surfactant). Materials and Methods: The physicochemical properties evaluated were pH, surface tension, free available chlorine (FAC) and contact angle. Cytotoxicity was evaluated in L929 fibroblasts exposed to the solutions by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide and neutral red assays. Assessment of penetration into dentinal tubules was performed by staining single-rooted permanent human teeth with crystal violet (n = 9), which were irrigated with the solutions and analyzed in cervical, middle and apical segments. Data were analyzed by one-way analysis of variance (ANOVA) and Tukey's post-test, 2-way ANOVA and Bonferroni's post-test or t-test (α = 0.05). Results: ChlorCid^TM Surf and ChlorCid^TM FAC values were close to those indicated by the manufacturer. ChlorCid^TM Surf showed lower surface tension and contact angle on dentin, and higher pH than ChlorCid^TM (p < 0.05). The penetration of ChlorCid^TM Surf was higher in cervical and middle segments, compared with ChlorCid^TM (p < 0.05). There was no difference in irrigant cytotoxicity (p > 0.05). Conclusions: ChlorCid^TM Surf showed lower surface tension, lower contact angle on root canal dentin, higher penetration into dentinal tubules and more alkaline pH, compared with ChlorCid^TM. However, both solutions showed similar cytotoxicity and FAC content.

• Archives of Pharmacal Research
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• 제27권6호
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• pp.646-652
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• 2004

The objective of this study was to determine the acute effect of trimetazidine (TMZ) on the pre-fatigue, fatigue and post-fatigue contractile characteristics and tension-frequency relationships of isolated rat diaphragm muscle. Muscle strips were taken from the ventral-costal aspects of the diaphragm muscle of rats killed by decapitation. The muscle strips were suspended in organ baths containing Krebs solution, with a gas mixture of 95% $O_2$ and 5% $CO_2$ at $37^{\circ}C$ and pH 7.35-7.45. After determining the thermoregulation and optimum muscle length the muscles were subjected to direct supramaximal stimulation with 0.05 Hz frequency square pulses for periods of 0.5 msec to obtain control values. After adding $5{\times}10^{-6}{\;}and{\;}5{\times}10^{-5}$ M trimetazidine solution to the respective bath media, the contractile parameters of the muscles were recorded. The contractile parameters were also recorded for both the trimetazidine and tri-metazidine-free media after application of the high frequency fatigue protocols. Later, the tension-frequency relationship was determined by applying stimulating pulses of 10, 20, 50 and 100 Hz to the muscle strips. Whilst the twitch tension obtained from the $5{\times}10^{-6}{\;}and{\;}5{\times}10^{-5}$ M trimetazidine media showed numerical increases compared to that of the controls, these were not statistically significant (p>0.05). The contraction time exhibited a dose dependent increase (p<0.001), whilst the contraction and relaxation rates did not differ significantly. The isometric contraction forces obtained with the different stimulating frequencies showed a significant increase in the tetanic contraction only at 100 Hz (p<0.05). A comparison of the pre- and post-fatigue twitch tensions in the trimetazidine media showed the post- fatigue twitch tensions to be significantly higher than those of the pre-fatigue contraction forces (p<0.05). In the $5{\times}10^{-6}{\;}and{\;}5{\times}10^{-5}$ M trimetazidine media the increases in the post-fatigue contraction force were 22 and 30%, respectively. These results demonstrated that in isolated rat diaphragm muscle, TMZ significantly limited the mechanical performance decrease during fatigue. It is our opinion that trimetazidine contributed to the observed fatigue tolerance by eliminating the factors of fatigue, due to preservation of intracellular calcium homeostasis, provision of the ATP energy levels needed by ATPase dependent pumps and especially by keeping the intracellular pH within cer-tain limits.

• 한국전문물리치료학회지
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• 제24권2호
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• pp.37-47
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• 2017

Background: Active trigger points (TrPs) of the suboccipital muscles greatly contribute to the occurrence of chronic tension-type headache, with increased sensitivity of TrPs and facilitated referred pain. Objects: This study aimed to investigate whether the integration of high-frequency diathermy into suboccipital release is more beneficial than the use of suboccipital release alone. Methods: Thirty subjects were assigned to either experimental group-1 (EG-1) to undergo suboccipital release combined with high-frequency diathermy (frequency: 0.3 MHz, and electrode type: resistive electronic transfer), or EG-2 to undergo suboccipital release alone, or the control group (CG) with no intervention, with 10 subjects in each group. The assessment tools included the headache impact test 6 (HIT-6), perceived level of tenderness, neck disability index, and neck mobility. Intervention was performed for 10 minutes, twice per week, for 4 weeks, and measurements were performed before and after the interventions. Results: The between-group comparison of the post-test values and changes between pretest and post-test showed significant differences for all parameters at p<.05, except for the left-to-right lateral bending range. In the post hoc test, EG-1 showed significant differences for the parameters in comparison with the CG, while no significant differences in the perceived tenderness level, on both temporal regions, were found between EG-2 and CG. Furthermore, the HIT-6 score and perceived tenderness level, in the right temporal region, showed significant differences between EG-1 and EG-2. In the within-group comparison, EG-1 and EG-2 appeared to be significantly different between pretest and post-test (p<.05), except for the perceived tenderness level in the right temporal region, with significance for the EG-1 group only (p<.05). Conclusion: These findings suggest that the suboccipital release technique may be advantageous to improve headache, tenderness, and neck function and mobility, with more favorable effects with the incorporation of high-frequency diathermy.

• 콘크리트학회논문집
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• 제21권3호
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• pp.347-358
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• 2009

최근에 들어서 국내에서도 무량판 구조 (flat plate slab)가 적용될 수 있는 여건이 마련되어가고 있다. 그러나 무량판 구조는 보가 없는 구조이기 때문에 일반적인 라멘구조형식에 비하여 처짐 제어가 어려우며, 포스트텐션 (post-tension) 공법은 이러한 문제점을 극복하기 위한 매우 효율적인 방법이다. 포스트텐션 구조를 적용하면 슬래브 두께의 증가 없이도 효율적으로 슬래브의 처짐을 제어 할 수 있다. 그러나, 이러한 장점에도 불구하고, 국내에서 포스트-텐션의 적용은 비용증가, 기술적인 문제, 경험부족 등으로 인하여 그 적용이 매우 제한적이다. 따라서 전구간 포스트텐션 (full-PT)에 대한 부담을 줄이고 나아가 기존 포스트텐션 구조형식의 시공성을 향상하기 위하여 본 연구에서는 슬래브 내부에서 긴장작업을 수행할 수 있는 상향긴장식 부분PT공법을 제안하였다. 이러한 상향긴장방식은 정착구를 필요에 따라 다양한 위치에 설치할 수 있기 때문에 처짐 효율에 대한 분석이 필요하며, 정착구 후면에서 인장응력을 야기시키는 문제점이 있다. 따라서, 본 연구에서는 상향긴장식 부분PT공법 적용할 때 정착구 위치에 따른 처짐효율분석, 유한요소해석 및 스트럿-타이를 이용한 인장응력 또는 인장력 해석 등을 실시하였으며, 상향긴장식 부분PT공법을 실제로 현장에 적용하고, 계측결과를 해석결과와 비교 분석함으로써 현장적용성을 알아보았다. 상향긴장식 부분PT공법은 처짐 또는 인장응력이 크게 발생되는 부분 구간에만 선택적으로 적용하면 적은 비용증가로 큰 처짐효율을 얻어낼 수 있음을 확인하였다.

• 한국공간구조학회논문집
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• 제14권4호
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• pp.65-72
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• 2014

To improve the noise and vibration problems of the existing public parking systems, new floor system was proposed. This system consists of the Sandwich Plate System(SPS), steel beam and post-tensioned steel tendons. To verify the dynamic characteristics such as the natural frequency and damping ratio of the system, the free vibration test was performed. Test results showed that the natural frequency of the SPS composite beam was 23.8Hz and it was increased by 3.8% by installing the post-tensioned tendons. The damping ratio of the specimen with tendons was about 1.64%.

• 한국지진공학회논문집
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• 제20권3호
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• pp.135-143
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• 2016

In this paper, a design concept of post-tensioned precast bridge piers was proposed to improve seismic behavior of the bridge pier. Mild reinforcing bars are placed continuously along the height of the column. Prestressing tendons are also provided to obtain re-centering capability for seismic events. Arrangement of the axial steels to prevent buckling of rebars at plastic hinge region was suggested and enhanced seismic performance was verified by experiments. Moment-curvature analyses were performed to evaluate the effect of effective prestress on seismic behavior after verifying the calculation method by cyclic tests of the precast columns. A real bridge pier was designed to investigate the seismic performance according to different level of effective prestress. Level of effective prestress showed obvious effect on crushing displacement but negligible effect on lateral displacement at fracture of tendons and reinforcements.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2010년도 춘계 학술대회 제22권1호
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• pp.19-20
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• 2010

본 연구는 전이슬래브의 두께를 줄이고 철근량을 감소시키기 위해 포스트텐션을 전이슬래브에 적용하는 포스트텐션 전이슬래브에 관한 연구이다. 본 논문에서는 전이슬래브와 같이 두꺼운 판요소 해석에 적합한 Wood-Armer 공식과 부착 긴장재를 사용한 포스트텐션 설계방법을 제안하고자 한다.

• 한방재활의학과학회지
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• 제28권1호
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• pp.161-166
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• 2018

This report describes the miniscalpel-acupuncture treatment of a 68-yr-old woman who had abnormal posture and involuntary dystonic movements of the head and neck. She suffered muscle contracture associated symptoms after she fell injured in 2014. Her neck had abnormal posture findings due to muscle tension. The spasms gradually worsened and did not respond to botulinum toxin injections. Involuntary dystonic movements may be due to peripheral post-traumatic cervical dystonia. Outcomes support cervical dystonia may be managed effectively with miniscalpel-acupuncture. Further research is recommended.

• Structural Engineering and Mechanics
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• 제53권6호
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• pp.1253-1269
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• 2015

The present paper investigates the post heating behavior of concrete beams reinforced with fiber reinforced polymer (FRP) bars, namely carbon fiber reinforced polymer (CFRP) bars and glass fiber reinforced polymer (GFRP) bars. Thirty rectangular concrete beams were prepared and cured for 28 days. Then, beams were either subjected (in duplicates) to elevated temperatures in the range (100 to $500^{\circ}C$) or left at room temperature before tested under four point loading for flexural response. Experimental results showed that beams, reinforced with CFRP and GFRP bars and subjected to temperatures below $300^{\circ}C$, showed better mechanical performance than that of corresponding ones with conventional reinforcing steel bars. The results also revealed that ultimate load capacity and stiffness pertaining to beams with FRP reinforcement decreased, yet their ultimate deflection and toughness increased with higher temperatures. All beams reinforced with FRP materials, except those post-heated to $500^{\circ}C$, failed by concrete crushing followed by tension failure of FRP bars.

• Journal of Advanced Marine Engineering and Technology
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• 제22권2호
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• pp.139-145
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• 1998

Filament winding method is widely used for composite fabrications using low viscosity liquid for-mation and processing asymmetrical structures of pressure vessel pipe rocket motor case etc. The filament winding method is affected by several parameters such as pot life of process time viscosi-ty of resin filament winding temperature and schedules curing condition and post curing condi-tion of resin. To develope high functional composite materials the rotation(5, 15, 20, 30rpm) of the winding machine was controlled by D.C motor. And the wiper to give proper tension was equipped between strand and resin bath. The resin is hooked by the design wiper. The adequate cure schedule was found by DSC. NOL ring test is carried out to investigate the basic physical properties such as design technology. The void contents in filament winding is generally higher than that of the prepreg laminated plate. These high contents of void can make a crack in resin in spite of low deformation. These problem was solved by giving tension in processing. To improve the characteristics of fiber volume fraction void contents resin/fiber bonding the winding speedc is changed under constant tension. It was found that resin impregnation was not different from in fiber contents void contents at the range of 0.5~1kg tension but it was found that resin was not impregnated at the above of 1.5kg tension. In burst test a pure PE liner was failed at a nozzle part under the $14kg/\textrm{cm}^2$ pressure but a pressure vessel of CNG was failed at a cylinder part under the $200kg/\textrm{cm}^2$ pressure.