• Title, Summary, Keyword: REBOUND

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The adiposity rebound in the 21st century children: meaning for what?

  • Kang, Min Jae
    • Clinical and Experimental Pediatrics
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    • v.61 no.12
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    • pp.375-380
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    • 2018
  • With the increase in the prevalence of overweight and obesity worldwide, early adiposity rebound, which is known to have a strong association with obesity, has recently been a focus of research. Early adiposity rebound is conventionally known to have a close relationship with non-communicable diseases. However, novel insights into early adiposity rebound have implied an acceleration of growth and puberty, which is directly reflected in the trends in the timing of adiposity rebound, in the 21st century compared with in the past. Furthermore, the observation that lean mass changes rather than fat mass changes show a more similar pattern to body mass index trajectories is interesting. In this article, the later outcomes and risk factors of early adiposity rebound are briefly summarized, and the current trends in the timing of adiposity rebound and novel insights into its relationship with body composition are reviewed.

Rebound excitability mediates motor abnormalities in Parkinson's disease

  • Kim, Jeongjin;Kim, Daesoo
    • BMB Reports
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    • v.51 no.1
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    • pp.3-4
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    • 2018
  • Parkinson's disease (PD) is a debilitating disorder resulting from loss of dopamine neurons. In dopamine deficient state, the basal ganglia increases inhibitory synaptic outputs to the thalamus. This increased inhibition by the basal ganglia output is known to reduce firing rate of thalamic neurons that relay motor signals to the motor cortex. This 'rate model' suggests that the reduced excitability of thalamic neurons is the key for inducing motor abnormalities in PD patients. We reveal that in response to inhibition, thalamic neurons generate rebound firing at the end of inhibition. This rebound firing increases motor cortical activity and induces muscular responses that triggers Parkinsonian motor dysfunction. Genetic and optogenetic intervention of the rebound firing prevent motor dysfunction in a mouse model of PD. Our results suggest that inhibitory synaptic mechanism mediates motor dysfunction by generating rebound excitability in the thalamocortical pathway.

Countermeasure of rebound reducing for wet-mixed steel fiber reinforced shotcrete (강섬유보강 습식 숏크리트의 리바운드 저감대책)

  • Lim Joo-Young;Park Hae-Geun;Lee Myeong-Sub;Cho Nam-Sup
    • Proceedings of the KSR Conference
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    • pp.1162-1167
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    • 2004
  • From the early 1980's, the New Austrian Tunnelling Method (NATM) has been developed as a one of the standard tunneling method in Korea. Owing to the results of many researches, the practical problems of shotcrete has been improved for a last decade. However, the excess amount of rebound still remains one of the critical problems in shotcrete technology. In order to improve for this rebound problem, recently developed cement mineral accelerator has been successfully applied to several NATM tunnels in Korea. An experimental investigation was carried out in order to verify the rebound characteristics of wet-mix Steel Fiber Reinforced Shotcrete (SFRS) with powder types cement mineral accelerator. Mortar setting test, SEM analysis, bonding test under spring water condition and rebound test were conducted. From the result, wet-mix SFRS with cement mineral acelerator exhibited excellent bonding characteristics even spring water condition and less rebound ratio compared to the conventional liquid accelerator.

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Film Boiling Heat Transfer Model of Spray Cooling Focusing on Rebound Motion of Droplets (액적의 리바운드 모션에 주목한 분무냉각 막비등 열전달 모델)

  • Kim, Yeung-Chan
    • Proceedings of the KSME Conference
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    • pp.1317-1322
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    • 2004
  • In this report, the heat transfer model of spray cooling on hot surface was developed by focusing on the effect of rebound motion of droplets. In the model, it was assumed that droplets rebound repeatedly on the hot surface and heat transfer upon droplet impact is proportional to sensible heat which heats up the droplets to the saturation temperature. In addition, to take account of the contribution of th heat flux upon impact of rebound droplets, it was assumed that the rebound droplets are distributed following the Gaussian distribution from 0 to L, which distance L is determined by maximum flight distance $L_{max}$. Also the calculated results were compared with existing experimental results.

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Mechanical Property, Thermal Conductivity, Rebound Resilience and Thermal Property of Chloro Isobutylene Isoprene Rubber/Ethylene Propylene Diene Monomer Blend

  • Hwang, Young-Bea;Lee, Won-Ki;Park, Chan Young
    • Elastomers and Composites
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    • v.53 no.2
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    • pp.80-85
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    • 2018
  • Chloro isobutylene isoprene rubber (CIIR) and ethylene propylene diene monomer (EPDM) compounded with other formulation chemicals, depending on the polymer blend, were prepared by mechanical mixing. After manufacturing the rubber vulcanizate by compression molding with a hot press, the mechanical and thermal properties including thermal conductivity, rebound resilience of the CIIR/EPDM blends were measured. As the EPDM rubber content increased, hardness and tension set showed a tendency to increase. Pure CIIR exhibited the lowest tensile strength; however, tensile strength increased with loading of EPDM rubber. On the other hand, in CIIR rubber, which is usually a low-rebound elastomer owing to a high damping effect, rebound resilience exhibited an increasing trend as the content of EPDM rubber increased. As the EPDM rubber content increased, thermal stability was improved due to reduction of decomposition rate in the rubber region of the blend vulcanizate.

Investigation on the Validities of Removal Time of the Forms Considering Rebound Number of P Type Shumidt Hammer (P형 슈미트 햄머의 반발도를 이용한 거푸집 탈형시기의 결정에 관한 타당성 검토)

  • 전충근;김상우;신병호;황인성;신병철;한천구
    • Proceedings of the Korea Concrete Institute Conference
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    • pp.909-912
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    • 2001
  • This paper presents the validities of the removal time of side forms considering the relationship between rebound number of P type schmidt hammer and compressive strength. According to test results, compressive strength of 40% of W/C at 12 hours shows 16kgf/$cm^{2}$ and 50% of W/C at 15 hours, 13kgf/$cm^{2}$. Rebound number at 9 hours after casting shows 13 and 9 (W/C 40% and W/C 50%). According to the regression analysis, rebound number of P type schmidt hammer to gain 50kgf/$cm^{2}$ of is estimated 20.1. It is thought that desirable rebound number of P type schmidt hammer to gain 50kgf/$cm^{2}$ is determined 25 considering safety factor.

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Estimation of Compressive Strength of Concrete with Granitic Aggregates : Rebound hammer and Ultrasonic Methods (화강암 골재를 사용한 콘크리트의 비파괴 시험에 의한 강도평가)

  • 김현우;이종태;윤기원;김병극;김무한;한천구
    • Proceedings of the Korea Concrete Institute Conference
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    • pp.651-654
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    • 1999
  • It is required that the compressive strength of concrete should be estimated accurately from the view point of efficient quality control and maintenance of buildings. In this paper, the equations to estimate the compressive strength of concrete using granite aggregates were suggested for both rebound hammer method and ultrasonic pulse velocity method. The results were compared with those for different age or curing condition. The rebound numbers for concrete cured in air were larger than for concrete cured in water. The difference between rebound numbers for concrete cured in water and in air was larger than for concrete cured in water. The difference between rebound numbers for concrete cured in water and in air was larger when water cement ratio was high. Also, with the increase of age, the velocity of ultrasonic pulse for concrete cured in air was measured larger when compared with that in water.

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An Experimental Study on the Mechanical Properties and Rebound Ratios of SFRS with Silica Fume

  • Son, Young-Hyun;Chai, Won-Kyu
    • International Journal of Safety
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    • v.8 no.2
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    • pp.20-25
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    • 2009
  • In this study, an experiment in the field was performed to analyze the mechanical properties and the influence of steel fiber and silica fume on the rebound ratios of shotcrete. The experimental parameters which are the reinforcing methods (steel fiber, wire mesh), steel fiber contents (0.0%, 0.5%, 0.75%, 1.0%), silica fume contents (0.0%, 10.0%), layer thickness (60 mm, 80 mm, 100 mm), and the placing parts (sidewall, shoulder, crown) were chosen. From the mechanical test, it was found that the flexural strength and toughness is significantly improved by the steel fiber and/or silica fume. According to the results for the side wall in this test, the larger the fiber contents are in case of steel fiber reinforced shotcrete, the less the rebound ratios are within the range of 20-35%, compared to the wire mesh reinforced shotcrte. And also, the reduced rebound ratios were very larger in using steel fiber reinforced shotcrete with silica fume content of 10%, and these results are true of the shoulder and the crown. respectively.

Prediction of rebound in shotcrete using deep bi-directional LSTM

  • Suzen, Ahmet A.;Cakiroglu, Melda A.
    • Computers and Concrete
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    • v.24 no.6
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    • pp.555-560
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    • 2019
  • During the application of shotcrete, a part of the concrete bounces back after hitting to the surface, the reinforcement or previously sprayed concrete. This rebound material is definitely not added to the mixture and considered as waste. In this study, a deep neural network model was developed to predict the rebound material during shotcrete application. The factors affecting rebound and the datasets of these parameters were obtained from previous experiments. The Long Short-Term Memory (LSTM) architecture of the proposed deep neural network model was used in accordance with this data set. In the development of the proposed four-tier prediction model, the dataset was divided into 90% training and 10% test. The deep neural network was modeled with 11 dependents 1 independent data by determining the most appropriate hyper parameter values for prediction. Accuracy and error performance in success performance of LSTM model were evaluated over MSE and RMSE. A success of 93.2% was achieved at the end of training of the model and a success of 85.6% in the test. There was a difference of 7.6% between training and test. In the following stage, it is aimed to increase the success rate of the model by increasing the number of data in the data set with synthetic and experimental data. In addition, it is thought that prediction of the amount of rebound during dry-mix shotcrete application will provide economic gain as well as contributing to environmental protection.

A Study on the Applicability of a Cumulative Rebound Angle for the Assessment of Compressive Strength of Construction Materials Nondestructively (건설재료의 비파괴 압축강도산정을 위한 누적 반발각의 적용성에 관한 연구)

  • Son, Moorak;Jang, Byungsik;Kim, Moojun
    • Journal of the Korean Geoenvironmental Society
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    • v.18 no.2
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    • pp.39-45
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    • 2017
  • This paper is to grasp the applicability of a cumulative rebound angle measured from the rebound action generated after impacting an object for the assessment of compressive strength of construction materials nondestructively and to propose the test results. For this study, an impact device was devised and used for impacting an object by an initial rotating free falling impact and following repetitive impacts from the rebound action which eventually disappears. Five types of construction materials, which are soil cement, cement paste, wood (pine tree), and two types of rock (shale and granite), were tested and both peak rebound angle and cumulative rebound angle were measured for each material by using a high-speed camera. The measured angles were compared with the directly measured compressive strength for each material. The comparison showed that for materials such as cement and rock the cumulative rebound angle, which reflects energy dissipation, rather than the peak rebound angle is more appropriate indicator for assessing the compressive strength of a material, but for a construction material such as wood which has a high toughness the magnitude of rebound is not an indicator to assess the compressive strength of a material.