• Steel and Composite Structures
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• 제43권5호
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• pp.553-564
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• 2022

Many existing reinforced concrete (RC) structures need to be strengthening for reason such as poor construction quality, low ductility or designing without considering seismic effects. One of the strengthening methods is strengthening technique with eccentrically braced frames (EBFs). The characteristic element of these systems is the link element and its length is very important in terms of seismic behavior. The link element of Y shaped EBF systems (YEBFs) is designed as a short shear element. Different limits are suggested in the literature for the link length. This study to aim experimentally investigate the effect of the link length for the suggested limits on the behavior of the RC frame system and efficiency of strengthening technique. For this purpose, a total of 5 single story, single span RC frame specimens were produced. The design of the RC frames was made considering seismic design deficiencies. Four of the produced specimens were strengthened and one of them remained as bare specimen. The steel YEBFs were used in strengthening the RC frame and the link was designed as a shear element that have different length with respect to suggested limits in literature. The length of links was determined as 50mm, 100mm, 150mm and 200mm. All of the specimens were tested under cyclic loads. The obtained results show that the strengthening technique improved the energy consumption and lateral load bearing capacities of the bare RC specimen. Moreover, it is concluded that the specimens YB-2 and YB-3 showed better performance than the other specimens, especially in energy consumption and ductility.

• 한국구조물진단유지관리공학회 논문집
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• 제12권6호
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• pp.225-232
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• 2008

본 논문에서는 FRP 보강재의 부착방식에 따른 RC보의 휨보강 성능평가에 대하여 연구하였다. 기존의 FRP 휨보강공법은 보강재의 형태에 따라 크게 FRP 쉬트 보강공법과 FRP 플레이트 보강공법으로 분류될 수 있으며, 각 공법은 에폭시의 양생기간동안 쉬트의 들뜸이 발생하지 않도록 주의해야하거나, 앵커설치 등 시공이 복잡하며, 인력이 많이 소요되는 단점이 있다. 이러한 문제점을 개선하기 위하여 본 논문에서는 Velcro형 고정재를 사용하여 FRP 플레이트를 임시 고정하는 보강공법을 제안하였고, 이에 대한 휨보강 성능평가 실험을 실시하였다. 실험은 FRP보강재의 부착방식을 변수로 하여 총 4개 실험체에 대하여 수행하였다. 실험결과 벨크로형 FRP판 보강공법은 타 공법에 비하여 우수한 시공성을 가짐과 동시에 휨내력이나 연성도 면에서도 우수한 보강성능을 확보하고 있는 것으로 나타났다.

• 한국공간구조학회논문집
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• 제14권4호
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• pp.73-80
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• 2014

For the last decade many bridges and buildings have experienced flexural strengthening with the fiber reinforced polymer(FRP) bonding system, demands for increasing heavy traffic loads and the changing of the code application. Of the many strengthening systems, NSM(near surface mounted) system with FRP has become attractive and popular way of strengthening for the existed RC structures and many studies and applications of this technique have significantly increased all over the world. Meanwhile, polymer mortar that contains much of the same ingredients as cement but includes the addition of certain polymer resins for enhancing desired physical properties, has been used as an alternative adhesive. This paper focuses on flexural behaviour of CFRP-bar NSM system with variables such as kinds of adhesive, anchorage, sectional aspect ratio. Based on the test results and test-to-predicted ratio, this paper provides researchers and practical engineers a fundamental knowledge and intuition.

• The Journal of Korean Physical Therapy
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• 제31권5호
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• pp.311-316
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• 2019

Purpose: Generally, patients with stroke present with decreased balance and increased spasticity following weakness of the paralyzed muscles. Muscle weakness caused by stroke has two causes. This is caused by a decrease in motor output and an adaptive muscle change, resulting in muscle weakness and muscle paralysis. The purpose of this study was to investigate the effect of strengthening exercise on balance and spasticity in chronic stroke patients and to suggest the basis of clinical treatment. Methods: Twenty subjects were divided into two groups: a lower-extremity strengthening group (experimental group) and a general physical therapy group (control group). The sliding stander equipment was used for the experimental group and a regimen of warm-up exercise, the main exercise routine, and cool-down exercise were used for the muscle strengthening exercise program. Balance and spasticity were measured before and after the training period. Balance ability was measured by the Berg balance scale, the Timed up and Go test and the weight distribution of the paralyzed muscles by the Spacebalance 3D. Spasticity was measured by the Biodex system. Results: After the training periods, the experimental group showed a significant improvement in BBS, weight distribution of the paralyzed muscles, and decreased spasticity when compared to the control group (p<0.05). Conclusion: This study supported the hypothesis that lower-extremity strengthening exercise improves the balance and decreases the spasticity of stroke patients. If it is combined with conventional neurologic physiotherapy, it would be effective rehabilitation for stroke patients.

• 대한통합의학회지
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• 제2권2호
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• pp.31-40
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• 2014

Purpose : To evaluate the effect of cervical strengthening exercise on balance ability in healthy adults. Method : The subjects consisted of forty healthy people. The subjects were divided into two group. The control group(n=14) received no exercise and/or stimulation. The cervical strengthening exercise group(n=14) performed therapeutic intervention using cervical exercise for strengthening of cervical spine muscle. The exercise group were accomplished during 6 weeks(2~3set, 5times/week). All tests were completed before and after experiment. The static balance ability was measured by normal standing when subjects open and close their eyes on GOOD BALANCE SYSTEM, respectively. For each case, the experimental data were obtained in 3 items: mean X speed, mean Y speed and velocity moment. Result : The results of this study were as follows; 1. In the exercise group, the statistically significant difference were shown on X speed and Y speed in the case of normal standing when subjects open and close their eyes and X speed, Y speed and velocity moment in the case of normal standing when subjects close their eyes(p<0.05). 2. In control group, the statistically significant difference were not shown on all posture(p>0.05). 3. There were a statistically significant difference in the X speed and Y speed in the case of normal standing when subjects open their eyes between control group and the exercise group(p<0.05). There were a statistically significant difference in the X speed, Y speed and velocity moment in the case of normal standing when subjects close their eyes between control group and exercise group(p<0.05). Conclusion : The above results revealed that therapeutic intervention for muscle strengthening of cervical there were positive changes to balance ability.

• 콘크리트학회논문집
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• 제19권2호
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• pp.225-231
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• 2007

최근 건설 산업에서 FRP는 재료적 장점들 때문에 구조물의 보강재로서 높은 관심을 모으고 있다. 본 연구에서는 CFRP 보강량에 따른 철근콘크리트 보의 구조적 거동과 보강된 CFRP 종류에 따른 보의 연성에 대해 연구한 것이다. 실험에서 보강량을 증가시켜 실험했을 때 실험체를 겹 보강하는 것보다는 폭 보강하는 것이 더 효율적이었다. CFRP로 보강된 보의 파괴에서는 휨 파괴를 일으키면서 취성적인 양상을 보였다. 또한 에너지 비 측면에서 보의 대부분이 취성 파괴로 분류되었다. CFRP 플레이트에 비해 쉬트의 에너지 비가 전체적으로 50%를 넘고 겹 보강을 하지 않은 실험체는 약 70% 정도로 나타났다.

• 한국구조물진단유지관리공학회 논문집
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• 제10권1호
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• pp.165-172
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• 2006

최근 손상된 부재를 원상으로 회복하면서 보강할 수 있는 프리스트레스 보강공법에 대한 관심이 고조되고 있다. 손상된 부재를 보강하기 위한 기존의 포스트텐션공법은 구조부재에 추가적인 손상을 발생시킬 수 있으므로, 인접부재에 손상을 주지 않는 새로운 형태의 부분프리스트레스공법에 관한 개발 및 성능평가가 요구된다. 본 연구에서는 새로운 외부포스트텐션공법 중 하나인 아웃케이블 공법에 대한 구조성능을 평가하기 위해 휨 보강된 연속보에 관한 실험적 연구를 수행하였다. 그 결과, 기존 포스트텐션과 아웃케이블공법의 주요 파괴모드는 균열이 고르고 넓게 분포한 휨파괴의 형태를 나타냈다. 그리고, 초기의 휨균열 시 강성 및 철근항복 시 강성, 항복하중, 최대하중에서 유사한 거동특성을 보임으로써 두 공법에 의한 보강효과는 동일한 결과를 보였다.

• 한국게임학회 논문지
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• 제19권2호
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• pp.55-66
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• 2019

본 연구는 게임콘텐츠 관련 전문가들이 지능정보시대에 콘텐츠산업의 변화를 어떻게 인식하고 있고, 콘텐츠산업 정책 중에서 어떤 평가요인에 우선순위를 두고 있는가에 대해 살펴보았다. 이를 위해 계층분석과정을 이용하여 콘텐츠산업 정책 평가요인들의 상대적 중요도와 우선순위를 분석하였다. 분석결과, '콘텐츠 기술역량 강화', '콘텐츠 전문인력 양성', '콘텐츠관련 제도개선', '콘텐츠 이용 및 소비자 안전강화'의 순으로 평가되었으며, 하위항목 분석에서는 '콘텐츠 R&D 체계구축 강화'가 가장 중요한 것으로 나타났다. 전문가집단별 분석에서는 산업계와 정책기관이 '콘텐츠기술역량 강화'를, 학계에서는 '콘텐츠 전문인력 양성'을 중요하게 평가하였다.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2009년도 춘계학술대회 논문집
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• pp.574-580
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• 2009

This study is investigate the bending behavior of real size RC beams strengthened with carbon fiber sheets. For experimental study, 1 control beam and 8 strengthened beams of real size(4 NU-beams and 4 U-beams) are tested and compared. NU-beam has not a V-shaped band and V-beam has a V-shaped band. The variables of experiment are composed of the number of carbon fiber sheets, the existence of U-shaped band, and four point loading, etc. The experimental results showed that the strengthening system with U-shaped band controls the premature debonding and provides a more ductile failure mode than the strengthening system without V-shaped band. It can be found from the load-deflection curves that as the number of fiber sheets is increased, the maximum strength and the flexural rigidity is increased. For the strengthening method with carbon fiber sheets of the real size RC beams, it is required the finding a solution to the bonding problem.

• International Journal of Concrete Structures and Materials
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• 제7권1호
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• pp.3-16
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• 2013

Strengthening concrete structures using FRP composites is a commonly considered technology in many practical situations. The success of the strengthening intervention largely depends on adequate bond between FRP sheets and the concrete substrate. In recent years, techniques to anchor FRP sheets in applications where sheets must develop strength in a short length have been proposed. One of these techniques includes use of FRP anchors embedded into the concrete substrate and forming part of the composite strengthening system. This paper presents the results of studies conducted recently at the University of Massachusetts Amherst to advance the understanding on the behavior of FRP anchored systems.