• Title, Summary, Keyword: Reducing Responses

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Experiment of a Liquid Damper Controlling Bi-directional Wind Responses of a Tall Building (초고층 건물의 양방향 풍응답 제어를 위한 액체댐퍼 실험)

  • Lee, Hye-Ri;Min, Kyung-Won
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.20 no.3
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    • pp.287-295
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    • 2010
  • This study deals with the design of a bi-directional damper using a tuned liquid damper(TLD) and a tuned liquid column damper(TLCD) for a SDOF building. Two dampers are usually needed to reduce wind-induced responses of tall buildings since they are along and across wind ones. The proposed damper has the advantage of controlling both responses with a single damper. The damper used in this study behaves as both a TLCD in a specific translational direction and a TLD in the other orthogonal direction. This paper presents experimental verification to confirm its control performance. First, shaking table test is carried out to investigate reducing responses by the damper. Control performance of the damper is expressed by the transfer function from shaking table accelerations to SDOF building ones. Testing results show that the damper reduced bi-directional responses of a SDOF building. Also, it reduced torsion responses.

Human Responses as Landscape Indicators of the Place Vulnerability (장소 취약도에 대한 경관지표로서의 인간의 대응)

  • HAN, Joo-Yup;LEE, Min-Boo
    • Journal of The Geomorphological Association of Korea
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    • v.19 no.1
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    • pp.109-121
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    • 2012
  • Human responses, such as construction of levees, are a spatial representation of the place vulnerability which is induced by a geomorphic hazard like flooding. Human responses include all forms of human activities to reduce the place vulnerability and they seem to be related with reducing vulnerability rather than reducing geomorphic hazards. Diverse human responses to the perceived environment bring about changes in the place vulnerability. People respond spatially to their vulnerability of the place in diverse ways from their experience and perceived risk. Human responses have quantitative possibilities in predicting and modeling the place vulnerability. Building the model of a dynamic place vulnerability to the diverse geomorphic hazards requires basic maps of geomorphic processes and human responses in the region.

Effect of a through-building gap on wind-induced loading and dynamic responses of a tall building

  • To, Alex P.;Lam, K.M.;Wong, S.Y.;Xie, Z.N.
    • Wind and Structures
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    • v.15 no.6
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    • pp.531-553
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    • 2012
  • Many tall buildings possess through-building gaps at middle levels of the building elevation. Some of these floors are used as sky gardens, or refuge floors, through which wind can flow with limited blockage. It has been reported in the literature that through-building gaps can be effective in reducing across-wind excitation of tall buildings. This paper systematically examines the effectiveness of two configurations of a through-building gap, at the mid-height of a tall building, in reducing the wind-induced dynamic responses of the building. The two configurations differ in the pattern of through-building opening on the gap floor, one with opening through the central portion of the floor and the other with opening on the perimeter of the floor around a central core. Wind forces and moments on the building models were measured with a high-frequency force balance from which dynamic building responses were computed. The results show that both configurations of a through-building gap are effective in reducing the across-wind excitation with the one with opening around the perimeter of the floor being significantly more effective. Wind pressures were measured on the building faces with electronic pressure scanners to help understand the generation of wind excitation loading. The data suggest that the through-building gap reduces the fluctuating across-wind forces through a disturbance of the coherence and phase-alignment of vortex excitation.

Control of 3-D coupled responses of wind-excited tall buildings by a spatially placed TLCD system

  • Liang, Shuguo;Li, Qiusheng;Qu, Weilian
    • Wind and Structures
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    • v.3 no.3
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    • pp.193-207
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    • 2000
  • The possible application of a spatially placed passive tuned liquid column damper system for suppressing coupled lateral-torsional responses of tall buildings is investigated in this paper. The wind loads acting on rectangular tall buildings are analytically expressed as 3-D stochastic model. Meanwhile, the 3-D responses of tall buildings may be coupled due to eccentricities between the stiffness and mass centers of the buildings. In these cases, torsional responses of the buildings are rather larger, and a TLCD system composed of several TLCD located near the sides of the buildings is more effective than the same TLCD placed at the building center in reducing both translational and torsional responses of the buildings. In this paper, extensive analytical and numerical work has been done to present the calculation method and optimize the parameters of such TLCD systems. The numerical examples show that the spatially placed TLCD system can reduce coupled along-wind, across-wind and torsional responses significantly with a fairly small mass ratio.

Application of tuned liquid dampers in controlling the torsional vibration of high rise buildings

  • Ross, Andrew S.;El Damatty, Ashraf A.;El Ansary, Ayman M.
    • Wind and Structures
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    • v.21 no.5
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    • pp.537-564
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    • 2015
  • Excessive motions in buildings cause occupants to become uncomfortable and nervous. This is particularly detrimental to the tenants and ultimately the owner of the building, with respect to financial considerations. Serviceability issues, such as excessive accelerations and inter-story drifts, are more prevalent today due to advancements in the structural systems, strength of materials, and design practices. These factors allow buildings to be taller, lighter, and more flexible, thereby exacerbating the impact of dynamic responses. There is a growing need for innovative and effective techniques to reduce the serviceability responses of these tall buildings. The current study considers a case study of a real building to show the effectiveness and robustness of the TLD in reducing the coupled lateral-torsional motion of this high-rise building under wind loading. Three unique multi-modal TLD systems are designed specifically to mitigate the torsional response of the building. A procedure is developed to analyze a structure-TLD system using High Frequency Force Balance (HFFB) test data from the Boundary Layer Wind Tunnel Laboratory (BLWTL) at the University of Western Ontario. The effectiveness of the unique TLD systems is investigated. In addition, a parametric study is conducted to determine the robustness of the systems in reducing the serviceability responses. Three practical parameters are varied to investigate the robustness of the TLD system: the height of water inside the tanks, the amplitude modification factor, and the structural modal frequencies.

The Effect of Physical Activity on Cardiovascular and Psychoaffective Responses to Stress (운동이 스트레스로부터의 심장 반응과 정서 반응에 미치는 영향)

  • Suh, Kyung-Hyun;Lee, Jae-Koo
    • Korean Journal of Health Education and Promotion
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    • v.24 no.3
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    • pp.21-34
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    • 2007
  • Objectives: This study aims to examined whether physical activity prevent the negative effect of psychological stress on cardiovascular reactivity by reducing stress induced sympathetic output and preventing norepinephrine depletion negative psych-affective responses. It is assumed that physical activity reduces the magnitude of cardiovascular responses and psychological responses to stress which threaten individuals' physical and mental health. The result of investigating the effect of physical activity on reducing negative physiological and psychological responses would suggest useful information health for practitioners who want to prevent stress-induced diseases, especially coronary heart disease. Methods: participants of this study were 30 students (10 males & 20 females), whose mean age was 21.30 (SD=2.29). Fifteen students (5 males & 10 females) were assigned for in each group, treatment and control groups. They were interviewed and given a survey that included a consent form, demographics sheet and psychological tests, such as State-Trait Anger Expression Inventory and State-Trait Anxiety Inventory. Before the application of psychological stress, participants in treatment group were going through with a course of physical exercise, running on treadmill 15minutes, while participants in control group were not physically active. After exercise, there was 15 minutes resting period before applying cognitive stress. During the experiment, all participants performed challenging cognitive tasks for 20minutes in situations that were designed to experience learned helplessness and measured their cardiovascular reactivity including blood pressure and heart rate every 5 minutes, until 10 minutes after finishing the application of psychological stress(recovering state). In the end of experiment, they were given some psychological test again. Results: Heart rates of exercise group were significantly higher than non-exercise group, especially, five minute after applying cognitive stress and at the end of recovery, in other word 10 minutes after stressful event. Systolic blood pressures of exercise group were lower than those of non-exercise group during the stressful event, but this differences in borderline level of significance. state anger level of exercise group decreased even experiencing stress, while those of non-exercise group increase. And state anxiety level of exercise group decreased in borderline level of significance. Conclusion: This study reiterate health benefits of physical activity and suggest that regular moderate exercise may regulate cardiovascular reactivity and psycho-affective responses from stress by reducing stress induced sympathetic output.

Effect of Progressive Muscle Relaxation using Biofeedback on Perceived Stress, Stress Response, Immune Response and Climacteric Symptoms of Middle-Aged Women (바이오피드백을 이용한 점진적 근육이완이 중년여성의 지각된 스트레스, 스트레스반응, 면역반응 및 갱년기 증상에 미치는 효과)

  • 정인숙
    • Journal of Korean Academy of Nursing
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    • v.34 no.2
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    • pp.213-224
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    • 2004
  • Purpose: This study was aimed to evaluate the effect of progressive muscle relaxation training using biofeedback on perceived stress, stress response, immune response and climacteric symptoms, Method: This was a crossover, pre-post test design, The study subjects are 36 middle-aged women who were selected at 2 public health centers, The independent variable was Biofeedback training for 4 weeks, twice a week and home training for 4 weeks, Dependent variables were perceived stress, stress response, immune response, and climacteric symptoms measured with Hildtch's scale (1996), Result: Progressive muscle relaxation training using biofeedback was not effective in reducing perceived stress, but it was shown to be effective in reducing physiological stress responses such as pulse rate and EMG, Though blood pressure and skin conductance were repeatedly down, and skin temperature slowly increased, there were no statistically significant differences. Progressive muscle relaxation training using biofeedback was not effective in reducing serum cortisol, enhancing immune responses, or decreasing climacteric symptoms. Conclusion: The findings point to a pressing need for further, well-controlled and designed research with consideration in selection of subjects and instruments, frequency of measurements, the sampling method, and intervention modalities.

Analysis of Multicategory Responses with Logit Model on Earlyold Age Pension

  • Kim, Mi-Jung
    • Journal of the Korean Data and Information Science Society
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    • v.19 no.3
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    • pp.735-749
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    • 2008
  • This article suggests application of logit model for analysis of multicategory responses. Referring to the reference category, characteristic of each category is obtained from analysis of polytomous logit model. With National Pension data it is illustrated that application of logit model helps it possible to find significant factors which may not be found only with polytomous logit model. Application of the logit model is done by reducing the number of categories. Categories are grouped into the former and the latter group according to reference category. Extra finding of significant factor was possible from logistic regression analysis for the two groups after removing the reference category. It is expected that this application would be helpful for finding information and characteristics on ordered multicategory responses where the proportional odds model does not fit.

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Effects of taper and set-back on wind force and wind-induced response of tall buildings

  • Kim, Yongchul;Kanda, Jun
    • Wind and Structures
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    • v.13 no.6
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    • pp.499-517
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    • 2010
  • Advances in structural materials and construction methods have resulted in flexible and light tall buildings, making an assessment of structural safety during strong wind and serviceability/habitability during comparable medium/weak wind important design criteria. So far, lots of studies on suppressing the wind-induced responses have been carried out for tall buildings with aerodynamic modification. Most of the studies on aerodynamic modification have forced on the corner modification, while the studies on taper and set-back are limited. Changes of sectional shape through taper and set-back can modify the flow pattern around the models, encouraging more 3-dimensionalities, which results in reducing the wind-induced excitations. This paper discusses the characteristics of overturning moments and wind-induced responses of the tall buildings with height variations. The reduction of mean along-wind and fluctuating across-wind overturning moments are apparent in the suburban area than in urban area. A series of the response analyses, the rms displacement responses of the tall buildings with height variations are reduced greatly, while the rms acceleration responses are not necessarily reduced, showing dependences on wind direction.

Effects of Late School-Aged Children's Perception of the Mother's Response to Negative Emotions and Ego Resilience on their Life Satisfaction (부정적 정서에 대한 어머니 반응 지각과 자아 탄력성이 학령기 후기 아동의 생활만족도에 미치는 영향)

  • Lee, Sang Hui;Lee, Sook
    • The Korean Journal of Community Living Science
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    • v.26 no.2
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    • pp.237-248
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    • 2015
  • This study examines the effects of late school-aged children's perception of their mother's responses to negative emotions and their ego resilience on their life satisfaction. Data were collected from 390 fifth- and sixth-graders residing in Kwangju, Korea. With the data, frequency, percentages, and Cronbach's ${\alpha}$ were calculated. Pearson's product moment correlation coefficients and hierarchical regression analyses were also considered. The effects of various variables on life satisfaction were analyzed, and according to the results, vitality had the greatest effect on life satisfaction, followed by vitality, optimism, emotional coaching responses, interpersonal relationships, emotion-reducing responses, emotion control, and the material employment status, in that order. The study contributes to the literature by providing additional insights into the mother's desirable responses to children's negative emotions and highlighting the importance of positive ego resilience in children's life satisfaction through the elucidation of effects of late school-aged children's perception of their mother's responses to negative emotions and their ego resilience on their life satisfaction.