• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.28 no.6A
• /
• pp.809-817
• /
• 2008

Recently, the external prestressing method is being much frequently used in strengthening reinforced concrete structures because of it's excellent load resistance and serviceability increases comparing to other strengthening methods. However, it is true that the research on fatigue performance of concrete structures strengthened by the external prestressing using FRP tendons is rare. Therefore, the purpose of this study is to evaluate the safety and feasibility of the external prestressing method by analyzing the characteristics of the reinforced concrete beam strengthening using FRP tendons under repeated loads. Test variables adopted in this experimental study are the types of external prestressing material (steel or FRP tendon) and the repeated load ranges. The repeated load range have the minimum 50% of yield load of reinforced concrete beam and the maximum 70-85%. The test beams are loaded by 4 point loadings with 3 Hz sine wave. From this experimental study, it is confirmed that the reinforced concrete beams strengthened using FRP tendons have sufficient safety against fatigue, especially in FRP tendon itself, tendon at deviators and tendon at anchorages.

• Proceedings of the Korean Society of Computer Information Conference
• /
• 2009.01a
• /
• pp.169-172
• /
• 2009

본 논문은 SOM을 이용하여 비행슈팅게임을 하는 게이머의 긴장과 이완상태를 학습한다. 학습된 SOM을 이용해 게이머의 새로운 심박데이터가 입력되었을 때 긴장과 이완 상태에서 플레이하는 게이머의 인식을 제안한다. 게이머들은 비행슈팅게임을 플레이하면서 게임 환경들의 패턴들에 익숙해진다. 게이머들은 반복하면서 지루해지면서 자연스럽게 긴장감도 떨어지게 된다. 만약 긴장이완 정도를 알 수 있다면 게이머의 상태에 맞게 게임환경을 조절하여 긴장감을 유지할 수 있을 것이다. 본 연구에서는 비행슈팅게임을 하는 게이머의 심박신호를 이용하여 게이머의 긴장이완상태를 신경망 SOM으로 분류한다. SOM은 주어진 입력패턴에 정확한 답을 정해주지 않고 자기 스스로 학습하여 해답을 찾는 신경망중의 하나이다. 따라서 게이머의 심박신호는 SOM 학습을 통해 게이머의 긴장과 이완상태들을 군집화 할 수 있다. 비행슈팅게임을 20회 반복 플레이하여 SOM으로 게이머의 심박신호를 입력해 본 결과 긴장이완상태를 인식 할 수 있었다.

• Science of Emotion and Sensibility
• /
• v.5 no.1
• /
• pp.17-24
• /
• 2002

This research was the first step to develop Expert System for Evaluation of Human Sensibility, where human sensibility can be inferred from objective physiological signals. The study aim was to develop an algorithm in which human arousal level can be judged using measured physiological signals. Fuzzy theory was applied for mathematical handling of the ambiguity related to evaluation of human sensibility, and the degree of belonging to a certain sensibility dimension was quantified by membership function through which the sensibility evaluation was able to be done. Determining membership function was achieved using results from a physiological signal database of arousal/relaxation that was generated from imagination. To induce one final result (arousal level) based on measuring the results of more than 2 physiological signals and the membership function of each physiological signal, Dempster-Shafer's Rule of Combination in Evidence was applied, through which the final arousal level was inferred.

• Proceedings of the Korean Society for Emotion and Sensibility Conference
• /
• 1999.11a
• /
• pp.407-412
• /
• 1999

본 연구에서는 향이 자율신경계에 미치는 영향을 알아보고자 100%의 Rose oil bulgarian, Lemon oil misitano, Jasmin abs., Lavender oil france (KIMEX co. Ltd)의 네가지 향을 사용하여 심전도, 피부온도, 피부저항의 생리신호를 측정하였고, 생리신호의 측정과 함께 주관적 설문지의 평가를 통해 생리신호와의 상관성을 살펴보았다. 주관적 평가 중 양극 척도의 긴장/이완에 해당되는 문항의 분석결과 장미>자스민>레몬>라벤더 순으로 피험자들에 의해 장미가 가장 긴장된다는 결과를 나타냈다. 향의 선호도 조사에서는 장미향이 가장 진한 향으로 레몬 향이 가장 좋은 향으로 분석결과가 나왔다. 생리신호 중 평균 R-R 간격의 측정 결과는 장미향에서 가장 긴장도가 높게 나타났으며 이에 따른 주관적 평가 결과 역시 장미향이 긴장도가 높게 나와 생리신호와 주관적 평가의 결과가 상관성을 가지고 있음을 알 수 있었고, 피부온도 결과에서는 평균 R-R 간격에서 긴장도가 가장 높은 장미가 피부온도가 가장 높게 나왔다. 피부저항은 레몬 향이 가장 긴장된 것으로 나온 반면 라벤더가 가장 이완으로 나타났으며 라벤더의 경우 주관적 평가와의 상관성을 가짐을 알 수 있었다. 이와 같이 향이 자율신경계에 미치는 영향을 알아보고자 주관적 평가와 생리신호를 동시에 측정하였는데 그 결과 주관적 평가와 생리신호의 상관성을 통해 향이 자율신경계에 어떤 영향을 미치는가를 알 수가 있었다.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.10 no.4
• /
• pp.145-154
• /
• 2006

This paper presents a method to enhance the load carrying capacity for a two-span continuous steel-concrete composite beam strengthened with external tendons. The tendon is placed at the bottom of steel beam where the positive bending moment occurs. This results in the reduction of the negative bending moment as well as the positive bending moment. This paper describes the procedure to determine the number of tendon and the initial tendon force for the target rating factor in the rating factor equation. An example beam is given to demonstrate the proposed procedure, and it validity is confirmed.

• Journal of the Korea Concrete Institute
• /
• v.21 no.3
• /
• pp.303-310
• /
• 2009

CFRP(carbon fiber reinforced polymer) tendons can be used as an alternative to solve the corrosion problem of steel tendons. Material properties of CFRP tendons such as bond strength, transfer length, and development length should be determined in order to apply to concrete structures. First of all, in case of application for pretension concrete members with CFRP tendons, transfer length is an important factor. A total of 9 beams have been cast to determine transfer length and development length of domestic CFRP tendon in this paper. Test results revealed that transfer length of the prestressing 25% and 50% are 34D, 55D respectively. Also, transfer length has increased as the prestressing force has increased. A change was observed in transfer length of developed CFRP tendon after 9 weeks. ${\alpha}_t$ of developed CFRP tendon was 2.3 similar to the steel strand.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.28 no.3A
• /
• pp.315-322
• /
• 2008

The present study applied the external post tensioning reinforcement method for reinforcing a non-ballast steel plate girder railway bridge, and the effects of the strength of tendons and the level of post-tensioning force on the dynamic behavior are experimented and analyzed. According to the results of this study, the natural frequency was increased by the strength of tendons but it was decreased by the rise of post-tensioning force and as a consequence the introduction of post-tensioning force decreased natural frequency slightly. It was analyzed that further study is need to establish the exact relations between post-tensioning force and natural frequency. In addition, it was found that the dynamic displacement, dynamic bending stress and vertical acceleration were decreased by the external post-tensioning. On the other hand, external post-tensioning increased horizontal acceleration by up to 20%, which was around 70% of vertical acceleration. This needs further study.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.28 no.5A
• /
• pp.747-756
• /
• 2008

The purpose of this paper is to investigate the effect of the important parameters on the transfer length during the dynamic flame cutting of tendon experimentally. The considered parameters were strand diameter, concrete cover thickness, stirrup, debonding strand and release method. Ten pretensioned concete beam specimens were cast and tested. Time history curves for the axial strain of tendon were measured by electrical resistance strain gauges mounted on the strands. Experimental results indicated that large dynamic shock effects occurred near cut-end during the sudden release. The prestressing forces are dependent on the parameters above considered. The ratio of residual prestressing forces of 12.7 mm strands is greater than 15.2 mm strands. Using debonding strand and gradual release are more efficient for applying prestressing forces.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2009.05a
• /
• pp.139-140
• /
• 2009

In this paper, the dynamic behavior of pretensioned concrete structures was investigated experimentally during detensioning for two different releasing methods: flame-cutting and hydraulic-jacking. According to the experimental results of strain changes, although detensioning time of hydraulic-jacking is shorter than that of fame-cutting, the prestressing force loss of fame-cutting is larger than that of hydraulic-jacking.

• Proceedings of the KAIS Fall Conference
• /
• 2010.05b
• /
• pp.645-648
• /
• 2010

본 연구는 이동식 긴장대의 실험결과와 유한요소해석프로그램(ABAQUS)을 사용한 해석결과를 비교, 분석하여 이동식 긴장대의 구조 성능을 평가한 것이다. 현재 사용되는 프리텐션방식의 PSC 거더는 공장에서 제작, 운반하여 현장에서 가설하는 방식이나 도로주행 여건에 의해 운반 가능한 부재의 크기가 제한됨에 따라 소규모 PSC 슬래브에만 프리텐션 방식이 적용되고 있다. 이에 본 연구에서는 현장에서 프리텐션 방식으로 PSC 거더를 제작할 수 있는 이동식 긴장대를 개발하고자 한다. 본 논문에서는 실험결과와 해석결과를 통하여 각 구성요소가 이동식 긴장대에 작용하는 긴장력에 저항하는 메카니즘을 파악하여 개발하고자 하는 이동식 긴장대의 구조적 특성을 파악하고자 하였다.