• 한국초전도ㆍ저온공학회논문지
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• 제24권1호
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• pp.13-17
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• 2022

The mechanical properties of REBCO coated conductor (CC) tapes under uniaxial tension are mainly determined by the thick layer Components like the substrate and the stabilizer. Depending on the applications of the CC tapes, it is also needed to externally reinforce thin metallic foils to one side or both sides of the CC tapes. This study investigated the effect of additional stabilizer layers or lamination on the electrical resistivity and electromechanical properties in RCE-DR processed GdBCO CC tapes with different structures. The strain/stress tolerance of I_c in differently processed 12 mm-wide REBCO CC tapes under uniaxial tension at 77 K and self-field could be determined by the loading-unloading scheme. As a result, Sn-Cu stabilized CC tape showed a significant decrease in mechanical properties due to its soft but thick stabilizing layer. However, similar electromechanical properties have been observed on both Sn-Cu and Sn-stabilized CC tapes, the I_c degradation behavior was independent of whether the CC tape has an external reinforcement or different stabilizing layers.

• Physical Therapy Rehabilitation Science
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• 제13권1호
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• pp.124-133
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• 2024

Objective: This study aims to investigate the immediate effects of myofascial release and Duoball assisted self-relaxation (DASR) techniques on pain and muscle tension in patients experiencing chronic cervical pain. Design: A randomized controlled trial. Methods: This study is a randomized controlled experimental study. Eighteen patients with chronic neck pain who met the selection criteria were randomly assigned to myofascial release group and myofascial release group using Duoball. Results: The frequency results for assessment muscle tension showed a decrease of about 10% in the suboccipital muscle, SCM, Pect m, UT, and LS in both the MFR and DASR groups, and the stiffness results showed a decrease in all muscles except the upper trapezius in the MFR group and the DASR group. All were found to decrease by about 10% in the suboccipital muscle, SCM, Pect m, UT, and LS, and the decrement results showed an increase of about 15% in the suboccipital muscle, SCM, Pect m, UT, and LS in both the MFR and DASR groups(p<0.05). Conclusions: In patients experiencing chronic neck pain, application of MFR and duoball assisted self relaxion was shown to be effective on pain and muscle tension. MFR is a non-pharmacological intervention method with few potential side effects and is considered a universal and easily applicable treatment method.

• 대한치과교정학회지
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• 제23권2호
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• pp.199-216
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• 1993

The purpose of this study was to quantify the biologic effects of the tensile forces from helical springs across the maxillary incisors on the periodontal tissues of rats. 39 Sprague-Dawlely rats were divided into a control group(3 rats) and three experimental groups(36 rats)-group 1, pressured with a light force(50-75g), group 2, with a heavy force(250-300g) and group 3, with a hen force(250-300g) plus laser irradiation. Autoradiographic and histopathologic observations were performed in 12, 24, 48 and 96 hours after force application. The result were as follow : 1. Hyalinized zone of periodontal ligament began to appear at pressure side in 12 hours in group 2 and group 3 ; all decreased in 96 hours except in group 2. 2. Alveolar bone resorption began to appear in 12 hours in group 2 and group 3 ; Group 2 showed more resorption than group 1 and no difference to group 3. 3. Tearing of periodontal ligament and vascular dilatation began to appear at tension side in 12 hours in all groups ; Group 2 showed more changes than group 1 and no difference to group 3 ; Decrease began to appear in 96 hours. 4. New bone formation began to appear at tension side in 12 hours and increased more and more ; No differences were shown of groups 5. New capillary proliferation began to appear at pressure side in 12 hours ; The changes were the greatest in group 3, group 2, group 1, in that order. 6. Positive reaction of cells to $[^3H]-thymidine$ was the greatest in 24 hours of all groups and decreased with times i Group 2 showed more reaction than group 1 and no difference to group 3.

• 한국초전도ㆍ저온공학회논문지
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• 제18권3호
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• pp.6-9
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• 2016

The enhancement of mechanical properties of coated conductor (CC) tapes in practical application are usually achieved by reinforcing through lamination or electroplating metal layers on either sides of the CC tape. Mechanical or electromechanical properties of the CC tapes have been largely affected by the lamination structure under various loading modes such as tension, bending or even cyclic. In this study, the influence of brass laminate volume fraction on electromechanical properties of RCE-DR processed Gadolinium-barium-copper-oxide (GdBCO) CC tapes was investigated. The samples used were composed of single-side and both-side laminate of brass layer to the Cu-stabilized CC tape and their $I_c$ behaviors were compared to those of the Cu-stabilized CC tape without external lamination. The stress/strain dependences of $I_c$ in laminated CC tapes under uniaxial tension were analyzed and the irreversible stress/strain limits were determined. As a result, the increase of brass laminate volume fraction initially increased the irreversible strain limit and became gradual. The corresponding irreversible stress limit, however, showed no difference even though the brass laminate volume fraction increased to 3.4. But the irreversible load limit linearly increased with the brass laminate volume fraction.

• Agricultural and Biosystems Engineering
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• 제4권1호
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• pp.34-38
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• 2003

A mathematical model was developed for estimating the mechanical interrelation between characteristics of soil and main design factors of a tracked vehicle, and predicting the tractive performance of the tracked vehicle. Based on the mathematical model, a computer simulation program (TPPMTV) was developed in the study. The model considered the continuous change in tension for the whole track of a tracked vehicle, the analysis of shape and tension of the track segment between sprocket and first roadwheel, and the side thrust on both sides of grouser by the active earth pressure theory in predicting the tractive performance of a tracked vehicle. Also, the model contained not only sinkage depth of the track but the pressure distribution under the track in analyzing the side thrust. The effectiveness of the developed model was verified by performing the draw bar pull tests with a tracked vehicle reconstructed for test in loam soil with moisture content of 18.92％. The predicted drawbar pulls by the model were well matched to the measured ones. Such results implied that the model developed in the study could estimate the drawbar pulls well at various soil conditions, and would be very useful as a simulation tool for designing a tracked vehicle and predicting its tractive performance.

• 한국강구조학회 논문집
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• 제15권1호
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• pp.25-31
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• 2003

본 연구는 데크플레이트의 모멘트 강도에 관한 실험적, 이론적 연구를 수행하였다. 실물크기의 14개 모멘트 실험을 행하였으며, 가력부의 국부좌굴을 방지하기 위해 1/4지점 집중하중을 가력하였다. 기준식들 간의 차이점을 이론적으로 비교분석하였다. 또한 미국 AISI, 유럽 EC3, 한국 기준과 실험값을 비교 평가하였다. 파괴모드는 보 중앙부의 국부좌굴 및 중간가력부의 국부좌굴에 의하여 형성되어 최대내력에 도달하였다. 인장측이 먼저 항복하는 경우 소성능력이 인장측에서 발휘되어 내력이 증대하였다. 설험결과는 인장측 부분 소성화를 고려한 EC 기준과 가장 잘 일치하였다. EC3 부록Z에 의한 통계학적 평가로부터 EC3 기준식이 목표로 하는 $^{\circ}{_M}=1.1$ 이내로 그 적용성이 만족되었다. AISI와 KS 기준에서도 소성화 개념을 추가한다면, 이론해석이 보다 더 개선될 것이다.

• 대한치과교정학회지
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• 제25권1호
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• pp.31-42
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• 1995

교정력에 의한 치아이동시 치주조직의 조직변화를 알아보고 성장인자중의 하나인 Epidemal Growth Factor (EGF)의 시간 경과에 따른 발현정도 및 분포 변화를 알아 보고자, Sprague-Dawley계 백서 23마리를 대조군(3마리)과 실험군(20마리)으로 나누었으며, 실험군은 교정력(75g)을 가한 후 12시간, 1일, 4일, 7일, 14일이 경과한 후 각각 4마리씩 희생시켜, EGF의 발현 분포와 조직학적 변화를 면역조직화학적 및 조직병리학적으로 관찰한 바 다음과 같은 결과를 얻었다. 1. 교정력을 가한 후 14일 까지, 견인측의 치주인대 섬유는 신장되었고, 압박측의 치주인대 섬유는 압축되었으며 치주인대섬유 배열의 완전회복은 일어나지 않았다. 2. 대조군의 EGF 발현은 구강상피, 전상아질, 치수와 치주인대내의 혈관에서 진하게 발현되었으나, 파골세포 및 골아세포에서는 미약한 염색상을 보였다. 3. 교정력을 가한지 12시간, 1일, 4일, 7일째 실험군의 치주조직에서의 EGF의 발현은 견인측과 압박측의 차이가 없이, 경미한 미만성의 양성반응을 보였다. 4. 교정력을 가한지 14일째 치주조직에서 EGF의 발현이 현저히 증가되었으며, 압박측보다 견인측이 더 많이 발현되었으며, 치경부 쪽보다 치근단 쪽에서 더 많았다.

• 대한치과보철학회지
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• 제35권2호
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• pp.401-412
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• 1997

There has been many researches aimed at reinforcing the strength of resin, and these have led to the development and use of numerous materials in recent years. A case in point, is the recent development of plasma-treated polyethylene fiber which has been used mainly in fixed provisional restoration to reduce the incidence of fractures. This study aims at assessing whether plasma-treated polyethylene fiber as applied to composite resin is effective in increasing the flexural strength and how applied portions affect this. Twenty-four applied and eight unapplied composite resin bars were fabricated. Twenty-four applied specimens were divided into three groups. Plasma treated polyethylene fiber was applied to the groups each with different portions of composite resin. In the first group, plasma-treated polyethylene fiber was not applied. In the second group, fiber was applied to the compression side of composite resin. Fiber was applied to the tension side in the third group, while fiber was embedded in the tension side of the composite resin in the fourth group. Each specimen was tested by use of a three-point bending strength test with an instron testing machine, and the flexural strength was calculated. The following results were obtained. : 1. Under the conditions of this study, the third and fourth groups demonstrated a statistically greater flexural strength compared to the first and second groups. 2. But there was no statistically significant difference, not only between the first group and the second group, but also between the third group and the fourth group. Taken together, it can be concluded that plasma-treated polyethylene fiber applied to composite resin is an effective method in increasing flexural strength, and the best way of increasing the flexural strength is by application of plasma-treated polyethylene fiber to the tension side, or the embedding of same in composite resin. It must be mentioned however that this test used a static single-load test method. This method determined the maximum stresses that could be tolerated, but this might not be valid where the prediction of clinical failure is concerned. In order therefore to clinically utilize plasma-treated polyethylene fiber to reinforce the composite resin, it is suggested that a further study which considers the various loads be undertaken.

• 소성∙가공
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• 제7권1호
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• pp.23-35
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• 1998

In order to analyze the tensile deformation characteristics of laser welded tailored blanks. laser welded blanks of different thikness and strength combinations were prepared and tensile tests were done. The tensile elongation along the direction perpendicular to weld line of laser welded blanks was reduced as increasing the deformation restraining force (strength X thicknes) ratio between two welded sheets and fracture occurred at weaker side of base sheets if void ration of welded sheets and fracture occurred at weaker side of base sheets if void ratio of weld section was less than 45% The tensile elongation along weld line reached above 90% of the elongation of base material if welding was done perfectly. Total elongation along the direction perpendicular to weld line was able to be predicted by force equilibrium and power law behavior of base sheets and it was related with the deformation of stronger sheet and formability of weaker side.

• Advances in concrete construction
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• 제10권4호
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• pp.279-287
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• 2020

The practice of splicing reinforcing bars in reinforced concrete structures to manage insufficient bar length is a common approach, which is mainly due to transportation limitations on bar length. The splicing of reinforcing bars side by side offers a simple and economical solution to the problem of continuity. This paper examines the influence of different structural parameters such as concrete cover, lap splice length, shear links confinement and concrete strength on the lap splices based on an extensive experimental database of laps and anchorage. The current study shows that increasing the lap splices beyond 50Ø has no additional benefit for increasing its strength. The results also show that relative to the measured stress, specimens with larger concrete side covers shows higher splice stress compared to the samples with smaller concrete covers.