• Title/Summary/Keyword: bridging

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The Influence of Cyclic-bending Moment on the Delamination Zone and the Fatigue Crack Propagation in A15052/AFRP Laminates (반복-굽힘 모멘트가 A15052/AFRP 적층재의 층간분리 영역과 피로균열진전에 미치는 영향)

  • Song, Sam-Hong;Kim, Cheol-Woong
    • Proceedings of the KSME Conference
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    • 2000.11a
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    • pp.231-237
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    • 2000
  • A15052/AFRP laminates were developed principally to obtain a material with good fatigue strength, in which possible cracks would grow very slowly. Weight savings of more than 30% should be attainable in practice. Also, the crack bridging fibers could still was carry a significant part of the load over the crack, thus the COD and stress intensity factor was reduced at the crack tip. A15052/ AFRP laminates consists of three thin sheets of 5052-H34 aluminum alloy and two layers of [0] unidirectional aramid fiber prepreg. The cyclic-bending moment test was investigated based on applying the five kinds of bending moments. The size of the delamination zone produced between 5052-H34 aluminum alloy sheets and fiber-adhesive layers was measured from ultrasonic C-scan pictures taken around the fatigue crack. In addition, the relationship between the cyclic-bending moment and the delamination zone size was studied and the effect of fiber bridging mechanism was also considered.

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A Study on the EMG Activity of Abdominal Muscles with Stable and Unstable Bridging Exercises in Individuals with Healthy Subjects

  • Lee, Jun Cheol
    • Journal of International Academy of Physical Therapy Research
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    • v.8 no.1
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    • pp.1077-1083
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    • 2017
  • The purpose of this study was to investigate the effects of stable and unstable bridging exercises on the EMG activity of abdominal muscles. Twenty healthy women participated in this study and the muscle activities of left-right rectus abdominis (RA), external oblique (EO), and internal oblique (IO) muscles were recorded during 4 bridging exercises (unilateral/ bilateral, stable/unstable). The activity of the right EO muscle was the highest during unilateral exercise in unstable condition, and left EO muscle also produced the same result. The activity of the right IO muscle was the highest during unilateral exercise in an unstable condition, and left IO muscle also produced the same result. The activity of the right RA muscle was the highest during unilateral exercise in a stable condition, and left RA muscle produced the same result. Unstable/unilateral (USUL) represented the highest activity among the 4 exercises. EO/IO muscles represented the highest activity during the USUL exercise, and RA did so during the stable/unilateral exercise. These results suggest that specific posture (USUL) can be administered targeting a specific side of abdominal muscles.

Structural Investigation of Infrared Transmitting $PbO-Bi_2O_3-Ga_2O_3$ Glasses by X-ray Photoelectron Spectroscopy (X-선 광전자 분광법(XPS)을 이용한 $PbO-Bi_2O_3-Ga_2O_3$계 적외선 투과 유리의 구조해석)

  • Heo, Jong;Kim, Choon-Gon;Kim, You-Song
    • Journal of the Korean Ceramic Society
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    • v.30 no.11
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    • pp.911-918
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    • 1993
  • X-ray photoelectron spectroscopy(XPS) has been empolyed to investigate the structure of PbO-Bi2O3-Ga2O3 glasses. XPS OIS spectra recorded from binary PbO-Ga2O3 glasses clearly showed the presence of two peacks due to bridging and non-bridging oxygens, respectively. Gaussin best-fit deconvolution of the OIS peaks suggested there are substaintial amount of non-bridging oxygens in the structure. Therefore, in addition to the glassforming and charge compensating roles of PbO as suggested from the previous works, role of PbO as network modifiers needs to be considered. Addition of Bi2O3 to binary glasses resulted in the rapid decrease in the amount of non-bridging oxygens as well as in values of FWHM (Full Width at the Half Maximum intensity). It is believed that Bi2O3 form distorted BiO6 octahedra and therefore, work as intermediates. Infrared spectra also suggested that Ga2O3 behave as network-formers in the form of GaO4- tetrahedra.

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R-Curve Behavior of Particulate Composites of ${Al_2}{O_3}$ Containing SiC and $ZrO_2$: II. Theoretical Analysis (SiC와 $ZrO_2$를 함유하는 ${Al_2}{O_3}$ 입자복합체의 균열저항거동: II. 이론적 분석)

  • 나상웅;이재형
    • Journal of the Korean Ceramic Society
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    • v.37 no.4
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    • pp.368-375
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    • 2000
  • Fracture toughness of particulate composites of Al2O3/SiC, Al2O3/ZrO2 and Al2O3/ZrO2/SiC was analysed theoretically. According to the suggested particle bridging model for obtaining the R-curve height, the crack extension resistance for the long crack was linearly proportional to the residual calmping stress at the interface between the second phase and the matrix. It was also a function of the particle size and the content. It was confirmed that the rising R-curve behavior of Al2O3 containing 30 vol% SiC particles of 3${\mu}{\textrm}{m}$ was owing to the strong crack bridging by SiC particles. For Al2O3/ZrO2/SiC composites, the tensional stress from the 3${\mu}{\textrm}{m}$ SiC particles was large enough to activate the spontaneous transformation of the ZrO2. The crack extension resistance due to the particle bridging mechanism did not seem to be affected much by the coupled toughening, but its resultant toughness increase could be significantly smaller due to the dependency on the matrix toughness.

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The Effects of the Sling Strap Height on Trunk and hip Muscle Activation During the Bridging Exercise with Sling

  • Kim, Kwang-Su;Shin, Hwa-Kyung
    • The Journal of Korean Physical Therapy
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    • v.28 no.1
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    • pp.59-63
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    • 2016
  • Purpose: The objective of this study was to identify determine the effect of the strap height on muscular activity of trunk and lower limbs muscles during bridging exercise with a sling. Methods: The subjects of the study were 17 healthy male adults. In order to For measurement of muscular activity, body surfaces electrodes were placed on areas including erector spinae, multifidus muscles, gluteus maximus, and hamstring and the results was were recorded based on three different heights of strap, which are Levels 1, 2, and 3. Results: The muscular activities in erector spinae, multifidus muscle, and gluteus maximus were significantly different in at all three heights (p<0.05)., Level 3 showed the highest the compared to Levels 1 and 2. In hamstring muscle, there was significant difference in levels 1 and 2, also and levels 1 and 3 (p<0.05),. Bbut there was no significant difference between 2 and 3. The ration of muscular activities in multifidus muscles/erector spinae and gluteus maximus/hamstrings were significantly different for all three strap heights (p<0.05). Also, Level 3 showed higher than 1 or 2. Conclusion: The results of this study suggests to adjustment of the level III, that which has high activity level of multifidus and gluteus maximus affecting trunk stability during bridging exercise using a sling.

Electrophilic Attack of the Phenyl Isocyanate Carbon at the Bridging Imido Nitogen: Preparation and Structure of$ Mo_2({\mu-N(CONPh)Ph})({\mu-NPh)(NPh)_2(S_2CNEt_2)_2$

  • 김경;Lee, Soon W.
    • Bulletin of the Korean Chemical Society
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    • v.19 no.11
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    • pp.1211-1216
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    • 1998
  • Bis(diethyldithiocarbamato)ioxomolybdenum(VI), cis-MoO2(S2CNEt2)2, 1, reacted with chlorotrimethylsilane (Me33SiCl) to give a seven-coordinate, pentagonal bipyramidal complex MoOC12(S2CN]Et2)2, 3, in which the oxo ligand is trans to the chloride ligand and the two chloride ligands are mutually cis. The monooxo molybdenum complex bis(diethyidithiocarbamato)oxomolybdenum(IV), MoO(S2CNEt2)2, 2, reacted with phenyl isocyanate (PhNCO) to give an Mo dimer MO2{μ-N(CONPh)Ph}(μ-NPh)(NPh)2(S2CNEt2)2, 4, which contains an Mo-Mo bond, two diethyldithiocarbamato ligands, two terminal imido (NPh) ligands, and two bridging hnido (NPh) ligands. One of the two bridging NPh ligands seemed to have been attacked by the electrophilic phenyl isocyanate carbon, which suggests that the bridging imido NPh ligand is more nucleophilic than the terminal one. Crystallographic data for 3: monoclinic space group P21/c, a=8.908(l) Å, b=17.509(3) Å, c=12.683(2) Å, β=110.15(1)°, Z=4, R(wR2)=0.0611(0.1385). Crystallographic data for 4-THF: orthorhombic space group P212121, a=17.932(4) Å, b=22.715(5) Å, c=11.802(3) Å, Z=4, R(wR2)=0.0585(0.1286).

Effects of the PNF Stabilization Technique for the Hip Joint and the Bridging Exercise on the Trunk Stabilizer Muscles in Healthy Adults (고관절에 적용한 PNF 안정화 기법과 교각운동이 요부안정화 근육에 미치는 영향)

  • Kim, Yong-Hun;Jung, Ju-Hyeon
    • PNF and Movement
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    • v.15 no.1
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    • pp.51-56
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    • 2017
  • Purpose: The purpose of this study was to examine the effects of the PNF stabilization technique for the hip joint and the bridging exercise on the trunk stabilizer muscles in healthy adults. Methods: Twenty-eight healthy adults were randomly allocated to either a PNF stabilization exercise group (n = 12) or a bridging exercise group (n = 16). The outcome measures included the contraction thickness ratio in the transversus abdominis (TrA), internal oblique (IO), and external oblique (EO), and the TrA lateral slide was assessed during the abdominal drawing-in maneuver using b-mode ultrasound. The researcher measured the abdominal muscle thickness of each participant before the therapist began the intervention and at the moment that the intervention was applied. Between-group comparisons were performed using the Mann-Whitney U test. The level of statistical significance was set at 0.05. Results: The PNF intervention program showed a significant increase in the trunk stabilizer muscle. The percentage of change in the TrA thickness showed a significant interaction between intervention. However, there were no significant differences in the IO and EO between the two groups. Conclusion: The PNF stabilization technique for the hip joint can be used effectively to improve the IO and TrA muscles in healthy adults.

The Potential of IPTV Service: Is It a Bridging or Gap-filling Telecommunication Service? (기존 신규 방송통신서비스 분석을 통한 IPTV 서비스의 성장가능성 연구)

  • Lee, Hyeongjik;Kim, Kyoungtae;Jeong, Bo Young
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 2009.05a
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    • pp.525-528
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    • 2009
  • This paper attempts to conceptually examine the potential of IPTV(Internet Protocol Television). First, this paper reviews the concept of a bridging telecommunication service and a gap-filling telecommunications service. Second, the current status of various emerging telecommunications services including mobile WiMax, called WiBro, and both satellite and terrestrial digital multimedia broadcasting service, called DMB are comprehensively analyzed. Based on those analysis, this paper analyzes whether IPTV is regared as a bridging telecommunications service or a gap-filling telecommunications service and examine the potential growth possibility of IPTV. Finally, the suggestions for policy makers are discussed.

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Effects of 4 Weeks Bridging Stabilization Exercise Using Swiss Ball and Whole Body Vibration on Balance and Gait Function in Elderly Women (4주간의 스위스 볼과 전신진동기를 이용한 교각안정화 운동이 노인 여성의 균형과 보행에 미치는 효과)

  • Kim, Tack-Hoon;Choi, Houng-Sik
    • Physical Therapy Korea
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    • v.18 no.3
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    • pp.49-58
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    • 2011
  • The purpose of this study was to evaluate the effects of bridging stabilization exercise on balance ability and gait performance in elderly women. The subjects of this study were thirty-one elderly women over 65 years old in HongSung-Gun Senior Citizen Welfare Hall. The subjects were randomly assigned into one of three groups (trunk stabilization exercise on the mat, whole body vibration, and Swiss ball) and participated in each exercise program three times a week for 4 weeks. Each exercise began in the bridging position. The dynamic balance and gait were measured by limit of stability area using force plate, Berg Balance Scale (BBS), and Timed Up and Go Test (TUG). The results were as follows: 1) The limit of stability in three groups increased significantly in anterior-posterior and medial-lateral lean after 4-weeks intervention (p<.05). 2) There were no significant differences in the limit of stability among three groups after 4-weeks intervention (p>.05). 3) The BBS and TUG in three groups increased significantly after 4-weeks intervention (p<.05). 4) There were significant differences among three groups in BBS. Post-hoc test showed that Swiss ball exercise group was significantly higher than the mat and whole body vibration groups. 5) There were no significant differences TUG among three groups after 4-weeks intervention (p>.05). In conclusion, this study suggested that 4 weeks of the bridging stabilization exercises were effective on balance and gait in all three groups. Particularly Swiss ball exercise group showed higher improvement than two other exercise groups (mat, whole body vibration group).

Progressive Fracture Analyses of Concrete by Finite Element Methods (유한요소법에 의한 콘크리트의 진행성 파괴해석)

  • 송하원
    • Magazine of the Korea Concrete Institute
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    • v.8 no.1
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    • pp.145-153
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    • 1996
  • The fracture process zone in concrete is a region ahead of a traction-free crack, in which two major mechanisms, microcracking and bridging, play important roles. The toughness due to bridging is dominant compared to toughness induced by microcracking, so that the bridging is dominani: mechanism governing the fracture process of concrete. Fracture mechanics does work for concrete provided that the fracture process zone is being considered, so that the development of model for the fracture process zone is most important to describe fracture phenomena in concrete. In this paper the bridging zone, which is a part of extended rnacrocrack with stresses transmitted by aggregates in concrete, is modelled by a Dugdale-Barenblatt type model with linear tension-softening curve. Two finite element techniques are shown for the analysis of progressive cracking in concrete based on the discrete crack approach: one with crack element, the other without crack element. The advantage of the technique with crack element is that it dees not need to update the mesh topology to follow the progressive cracking. Numerical results by the techniques are demonstrated.