• Title, Summary, Keyword: used shortening

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Evaluation of the influence of creep and shrinkage determinants on column shortening in mid-rise buildings

  • B-Jahromi, Ali;Rotimi, Abdulazeez;Tovi, Shivan;Goodchild, Charles;Rizzuto, Joseph
    • Advances in concrete construction
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    • v.5 no.2
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    • pp.155-171
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    • 2017
  • The phenomenon of concrete column shortening has been widely acknowledged since it first became apparent in the 1960s. Axial column shortening is due to the combined effect of elastic and inelastic deformations, shrinkage and creep. This study aims to investigate the effects of ambient temperature, relative humidity, cement hardening speed and aggregate type on concrete column shortening. The investigation was conducted using a column shortening prediction model which is underpinned by the Eurocode 2. Critical analysis and evaluation of the results showed that the concrete aggregate types used in the concrete have significant impact on column shortening. Generally, aggregates with higher moduli of elasticity hold the best results in terms of shortening. Cement type used is another significant factor, as using slow hardening cement gives better results compared to rapid hardening cement. This study also showed that environmental factors, namely, ambient temperature and relative humidity have less impact on column shortening.

Effect of Outriggers on Differential Column Shortening in Tall Buildings

  • Kim, Han-Soo
    • International Journal of High-Rise Buildings
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    • v.6 no.1
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    • pp.91-99
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    • 2017
  • Special consideration should be given to differential column shortening during the design and construction of a tall building to mitigate the adverse effects caused by such shortening. The effects of the outrigger - which is conventionally used to increase the lateral stiffness of a tall building - on the differential shortening are investigated in this study. Three analysis models, a constant-section, constant-stress, and general model, are prepared, and the differential shortenings of these models with and without the outrigger are compared. The effects of connection time, sectional area, and location of the outrigger on the differential shortening are studied. The sectional area of the outrigger shows a non-linear relation in reducing the maximum differential shortening. The optimum locations of the single and dual outriggers are investigated by an exhaustive search method, and it is confirmed that a global optimum location exists. This study shows that the outrigger can be utilized to reduce the differential shortening between the interior core wall and the perimeter columns as well as to reduce the lateral displacements due to wind or earthquake loads.

A Comparative Studies of Channel Shortening Techniques for OFDM System (OFDM시스템을 위한 채널 shortening기법들의 비교)

  • Kim, Jae-kwon
    • The Journal of Korea Institute of Information, Electronics, and Communication Technology
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    • v.6 no.4
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    • pp.262-266
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    • 2013
  • In OFDM system, cyclic prefix (CP) is used to eliminate the inersymbol interference that is caused by the channel dispersion. However, a long CP reduces the data transmission rate. An alternative to a logn CP is the a time domain channel shortening filter at the receiver that shortens the effective channel, thus a short CP is used in spite of a long channel impulse response. In the paper, we compare a various channel shortening techniques; minimum shortened signal to noise ratio (MSSNR), minimum interblock interference (min-IBI), and minimum ISI (min-ISI).

Prediction and Compensation of Differential Column Shortening in High-Rise Building Structures (고층건물 기둥의 부등축소량 예측 및 시공오차 보정에 관한 연구)

  • 조창휘;송진규;이현호;조석희
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • pp.258-266
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    • 1996
  • The purpose of this study is to make a reasonable correction in construction stage through exact prediction of long-time differential column shortening that occurs in the high-rise RC building. For this, a self-developed program adopted PCA code is used to predict differential column shortening with sequential loading process. Using this program, the amount of the different column shortening of Amatapura Apartment in Indonesia is predicted and the effect is analyzed. From the result, the major factor affecting the shortening amount in columns is elastic strain and the effect of shrinkage is very small rather than creep. And maximun differential column shortening is appeared near the middle of the building.

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Effect of Various Lipids in Dough on Yackwa Quality (반죽내의 유지가 약과의 품질에 미치는 영향)

  • 김소원;김명애
    • Korean journal of food and cookery science
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    • v.17 no.6
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    • pp.611-616
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    • 2001
  • This study was carried out to investigate the effect of various lipids on the quality of Yackwa. Sesame oil, soybean oil, margarine for cream, margarine for pie and shortening were used as lipid for making dough of Yackwa in this study. The expansion rate of Yackwa ranked in the order of shortening, margarine for pie, soybean oil, margarine for cream and sesame oil. The Yackwa made with shortening showed low hardness, cohesiveness, gumminess and brittleness such as the ones made with sesame oil. The Yackwa made with sesame oil was oily and showed the lowest acceptability, but the Yackwa of shortening gained the highest score of acceptability in sensory evaluation. In conclusion. this experimental result indicated that shortening would be very useful as a substitute for sesame oil in making Yackwa.

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A Study on the Prediction of Shortening for Steel-Reinforced Concrete(SRC) Column in the High-Rise Buildings (초고층 건물에서 철골철근콘크리트(SRC) 기둥의 축소량 예측에 관한 연구)

  • Jeong Eun-Ho;Kim Jeom-Han
    • Journal of the Korea Concrete Institute
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    • v.16 no.1
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    • pp.36-42
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    • 2004
  • Although steel-reinforced concrete(SRC) is widely used in a high-rise building, a methods used to predict the column shortening of SRC structural members has many problems in applying a theoretical equation which considers only the material characteristics of reinforced concrete. In this study, the degree of accuracy of the existing method calculating the column shortening of a high-rise building is examined. For this, first, the actual measurement data are chosen about the column shortening of a high-rise building established with SRC structural members. Then the column shortening of a SRC structural member is calculated through computer program. Finally, the comparison between the measurement data and the analytical ones is executed. According to this study, it can be concluded that there is little difference between the former and the latter. Therefore, the existing method can be used to evaluate the column shortening of a high-rise building using a SRC structural members.

The Effect of Stretch-Shortening Cycle on the Joint Power of the Jireugi in the Taekwondo Juchumseogi Stance (태권도 주춤서 지르기에서 Stretch-Shortening Cycle 이 관절파워에 미치는 효과)

  • Choi, Chi-Sun;Chung, Chul-Soo;Shin, In-Sik
    • Korean Journal of Sport Biomechanics
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    • v.24 no.1
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    • pp.1-9
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    • 2014
  • The purpose of this study was to investigate the muscle mechanical properties of the pelvic axial pre-rotational movement for the Jireugi in the Taekwondo Juchumseogi stance. Eleven elite Taekwondo Poomsae athletes participated. Each participant performed 5 right hand Jireugi in Juchumseogi stance as fast and strong as possible while their motion was recorded by a 3D motion analysis system and the ground reaction forces by two force plates. The power and work of the muscular group surrounding the waist were analyzed to verify the effect of the stretch-shortening cycle (SSC) theory. The cause of the greater power seems to be the application of the SSC by the muscles surrounding the waist during the preparation phase of the pre-rotation group. For the none pre-rotation group, they only used the concentric contraction of the muscles surrounding the waist. Because the pre-rotation group used the SSC theory, they had the effect of shortening of the range of movement, creating a fast and more powerful rotation, thus anticipating the increase the magnitude of impact.

A Three Way Contribution of Wheat Flour Lipids, Shortening and Surfactants to Bread-making (제빵과정에 있어서 밀가루 지방질, 쇼트닝 및 유화제의 역할)

  • Chung, Ok-Kyung
    • Korean Journal of Food Science and Technology
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    • v.13 no.1
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    • pp.74-89
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    • 1981
  • Breadmaking is a complex system in which many variables govern the production of acceptable bread. Lipids, a minor component of wheat flour, function importantly in bread-making. Shortening, or fat, is one of the essential ingredients in commercial baking. Beneficial shortening effect depends on type and quantity of lipids present in wheat flour and also on wheat flour quality. Surfactants have been used in baking industry during last decade because certrain surfactants can replace shortening and/or natural flour lipids. A proper combination of lipidshortening-surfactant is more useful in the production of specialty breads such as whole wheat breads, high protein breads, high fiber breads or even non-wheat composite breads rather than in the production of regular white breads. This presentation is a review of recent studies on the contribution of flour lipids, shortening, and surfactants, alone or in combination in the production of breads; illustrations are mainly from data obtained in the author's laboratory.

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Column Shortening Analysis of Composite Columns by Age-adjusted Effective Modulus Method (재령보정유효탄성계수법에 의한 합성기둥 축소량 해석)

  • Kim Han-Soo;Kim Jae-Keun;Kim Do-Kyoon
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • pp.490-495
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    • 2006
  • The analysis method proposed by PCA is widely used in calculating the column shortening of reinforced and composite columns of a tall building. However, residual creep factor which relates creep strain of reinforced concrete to creep strain of plain concrete is based on Rate of Creep Method (RCM) which has theoretical defects and is considered obsolete. In this paper, a new equation for the residual creep factor based on Age-adjusted Effective Modulus Method (AEMM) which is considered exact and better than RCM is proposed. The residual creep factor by RCM is found to be higher than one by AEMM, which means current PCA method overestimates the shortening of a reinforced concrete column. By using the residual creep factor by AEMM, more exact column shortening of a tall building can be obtainable with a simple modification to PCA method.

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Analysis of Material Tests for Predicting and Correcting the Shortening of Vertical Members (수직부재 축소량 예측 및 보정을 위한 재료시험 분석)

  • Park, Hee-Gon;Kwon, Hae-Won;Lee, Jin-Woo;Bae, Yeoun-Ki;Youn, Kang-Sup;Lee, Jae-Sam
    • Proceedings of the Korea Concrete Institute Conference
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    • pp.173-174
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    • 2009
  • With the recent emergence of high rise buildings, this study was conducted in order to examine shortening, which has been used only in civil engineering structures, in such buildings. Examination of the shortening of vertical members is basically focused on deformations caused by load applied to concrete, material characteristics, etc. Shortening is analyzed through calculating parameters from the factors or characteristics of concrete, but analysis in the aspect of material tests has been somewhat unsatisfactory. Thus, this study purposed to analyze basic material test items for correcting the shortening of vertical members, namely, columns, to determine the reliability of material tests before parameter calculation for correcting shortening, and to examine the performance of material tests.

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