• Computers and Concrete
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• 제8권4호
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• pp.445-463
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• 2011

In the design of reinforced concrete (RC) beams, apart from providing adequate strength, it is also necessary to provide a minimum deformability even for beams not located in seismic regions. In most RC design codes, this is achieved by restricting the maximum tension steel ratio or neutral axis depth. However, this empirical deemed-to-satisfy method, which was developed based on beams made of normal-strength concrete (NSC) and normal-strength steel (NSS), would not provide a consistent deformability to beams made of high-strength concrete (HSC) and/or high-strength steel (HSS). More critically, HSC beams would have much lower deformability than that provided previously to NSC beams. To ensure that a consistent deformability is provided to all RC beams, it is proposed herein to set an absolute minimum rotation capacity to all RC beams in the design. Based on this requirement, the respective maximum limits of tension steel ratio and neutral axis depth for different concrete and steel yield strengths are derived based on a formula developed by the authors. Finally for incorporation into design codes, simplified guidelines for designing RC beams having the proposed minimum deformability are developed.

• Journal of Electrical Engineering and Technology
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• 제13권2호
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• pp.752-760
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• 2018

In this paper, interior permanent magnet synchronous motor (IPMSM) design for sensorless drive, considering magnetic neutral point shift according to magnetic saturation, has been proposed. Sensorless control was divided into a method based on inductance and a method based on back induced voltage. Because induced voltage is very small at zero or low speed, error in rotor initial position estimation may occur. Using the ratio of saliency addresses this problem. When using high-frequency injections at low speed, the rotor's initial position is estimated at the smallest portion of the inductance. IPMSM has the minimum inductance at the d-axis. However, if magnetic saturation leads to magnetic neutral point variation, following the load current change, there is a change in the minimum point of inductance. In this case, it can lead to failure of initial rotor position estimation. As a result, it is essential that the blocking design has an inductance minimum point shift. As such, in this study, an IPMSM design method, by blocking magnetic neutral point change, has been proposed. After determining the inductance profile based on the finite element analysis (FEA), the results of proposed method were verified.

• Journal of Nutrition and Health
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• 제29권10호
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• pp.1142-1149
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• 1996

This study was conducted to determine changes in th contents and composition of dietary fiber during the growth of soybean sprout. Soybean was soaked in water at $25^{\circ}C$ for 2hrs and cultivated at 2$0^{\circ}C$ for 7 days under dark condition. The soybean sprouts were divided into cotyledon and axis and sampled every 24hrs. The analysis methodlogies used were Van Soest's NDF, AOAC's ADF and lignin and Prosky's IDF, SDF, TDF. The weight of 100 sprouts increased gradually from 20.26g to 90.12g during the growth periods. The weight increased to 344.9% of the original weight. The germination rate was 100% after soaking at $25^{\circ}C$ for 2hrs. Root length increased gradualy from 0.6cm at 1st day to 17.2cm at 7th day. The crude ash and crude fat contents showed no significant change in the cotyledon and axis. The crude protein contents increased in the cotyledon and axis, whereas the total carbohydrate content didn't have general tendency. The insoluble dietary fiber(IDF), soluble dietary fiber(SDF) and total dietary fiber(TDF) contents of cotyledon were no significantly different from 20.01%, 1.45%, 21.46% at 1st day to 22.75%, 2.07%, 24.82% at 7th day on dry basis. In axis those contents increased from 23.19%, 1.97%, 25.16% at 1st day to 32.78%, 3.02%, 35.80% at 7th day, respectively. The neutral detergent fiber(NDF) contents of cotyledon and axis increased from 4.35% to 6.39% and from 6.44% to 26.60% respectively on dry basis. The acid detergent fiber (ADF) contents of cotyledon and axis increased from 2.84% to 4.91% and from 2.5% to 4.7%, but there were no significantly different in the hemicellulose and lignin contents on dry basis. The hemicellulose and lignin contents of axis increased with culture periods from 1.70% to 4.41% and from 0.20% to 2.11%, respectively. The cellulose contents increased from 4.54% to 20.35% on dry basis.

• Advances in aircraft and spacecraft science
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• 제5권6호
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• pp.691-729
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• 2018

In this paper the hygro-thermo-mechanical vibration and buckling behavior of embedded FG nano-plates are investigated. The Eringen's and Gurtin-Murdoch theories are applied to study the small scale and surface effects on frequencies and critical buckling loads. The effective material properties are modeled using Mori-Tanaka homogenization scheme. On the base of RPT and HSDPT plate theories, the Hamilton's principle is employed to derive governing equations. Using iterative and GDQ methods the governing equations are solved and the influence of different parameters on natural frequencies and critical buckling loads are studied.

• 한국강구조학회 논문집
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• 제21권2호
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• pp.135-144
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• 2009

본 논문은 기존 SC합성보에 비부착 긴장재의 정착위치와 도입된 긴장량을 변수로하여 포스트텐션 공법으로 휨보강을 실시한 실험체의 보강성능을 평가하여 적절한 휨보강 방법을 제시하고자 하였다. 실험은 각 유형별 실험체를 항복하중까지 가력하고 항복 이후 비부착 포스트텐션 보강을 실시 추가 가력하여 보강성능을 조사하였다. 실험결과 보강된 SC합성보는 보강전에 비해 향상된 항복내력 및 초기강성을 나타냈으며 최대내력의 실험값/이론값은 보강 후 ${0.95{\sim}1.13}$으로 나타났다. 보강 전 중립축과 그 상부에 정착구를 설치한 실험체(D160, 240계열)는 최대내력에서 긴장력의 차이에 따른 변화는 거의 없고 오히려 긴장력이 증가하면 연성이 감소하였으며 보강 후 중립축에 졍착구를 설치한 실험체(D120계열)는 긴장력이 증가하면 최대내력이 증가하고 또한 연성도 증가하여 보강 후 중립축에 대한 적절한 긴장력 보강이 매우 유효함을 알 수 있었다.

• 한국초전도ㆍ저온공학회논문지
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• 제25권4호
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• pp.19-23
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• 2023

The Second-generation high-temperature superconducting (HTS) Rare-Earth Barium Copper Oxide (REBCO) wire is a composite laminate having a multi-layer structure (8 or more layers). HTS wires will undergo multiple loads including the bending-tension loads during winding, high current density, and high magnetic fields. In particular, the wires are subjected to bending stress and magnetic field stress because HTS wires are wound around a circular bobbin when making a high-field magnetic. Each of the different laminated wires inevitably exhibits damage and fracture behavior of wire due to stress deformation, mismatches in thermal, physical, electrical, and magnetic properties. Therefore, when manufacturing high-field magnets and other applications, it is necessary to calculate the stress-strain experienced by high-temperature superconducting wire to present stable operating conditions in the product's use environment. In this study, the finite element model (FEM) was used to simulate the strain-stress characteristics of the HTS wire under high current density and magnetic field, and bending loads. In addition, the result of obtaining the neutral axis of the wire and the simulation result was compared with the theoretical calculation value and reviewed. As a result of the simulation using COMSOL Multiphysics, when a current of 100 A was applied to the wire, the current value showed the difference of 10^-9. The stress received by the wire was 501.9 MPa, which showed a theoretically calculated value of 500 MPa and difference of 0.38% between simulation and theoretical method. In addition, the displacement resulted is 30.0012 ㎛, which is very similar to the theoretically calculated value of 30 ㎛. Later, the amount of bending stress by the circular mandrel was received for each layer and the difference with the theoretically obtained the neutral axis result was compared and reviewed. This result will be used as basic data for manufacturing high-field magnets because it can be expanded and analyzed even in the case of wire with magnetic flux pinning.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1990년도 봄 학술발표회 논문집
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• pp.122-127
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• 1990

The transfer of forces across the interface by bond between concrete and steel is of fundamental importance to many aspects of reinforced concrete behavior. Bond stress - slip relationships were studied using a symmetrical tension test specimen. This type of test is intented to simulate conditions in the tension zone of a concrete beam between primary cracks and below the neutral axis. These relationships between local bond stress and local slip are quite different at different locations along the bar. The present study allows more accurate analysis of reinforced concrete structures by employing more realistic bond stress-slip relations.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2004년도 춘계학술대회 논문집
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• pp.1148-1154
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• 2004

Parametric studies are executed by numerical method varying then number of strain gauges, rail section and distance of sleeper from which the followings are obtained. Wheel forces or lateral forces are measured by connecting eight strain gauges on rail to single Wheatstone bridge. The method eliminates the influence of interaction and measured stability. Strain gauges are fastened on the neutral axis of the rail so as not to be influenced by sleeper.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2009년도 춘계 학술대회 제21권1호
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• pp.41-42
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• 2009

이 연구에서는 프리스트레스 도입량과 부재 크기가 다른 두 타입의 강합성형 벽체파일 시험체에 대한 정적 휨시험을 수행하고 구조적 안전성을 검증하였다. 실험결과, 시험체 모두 균열하중의 1.8배의 하중에서 파괴되었고, 하중 증가에 따른 중립축의 이동을 확인하였다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2003년도 봄 학술발표회 논문집
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• pp.561-566
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• 2003

In this study, to predict the behavior of RC beam strengthened with Carbon fiber reinforced polymer(CFRP) plate, analytical program considering material non-linearity is developed. Strain compatibility and force equilibrium are applied and internal forces of constitutive material are calculated using nonlinear stress-strain relationship. Also, to certainty the reliability of analytical program, deflection, strain of CFRP plate, change of neutral axis on cross section and crack distribution at failure are compared with those of experiment, and each results are almost coincident.