석회석 소성 점토 시멘트(LC₃) 페이스트의 고온 내화성능에 관한 연구

왕소용 ( Wang¸ Xiao-yong ) 한국건축시공학회 2021 한국건축시공학회 학술발표대회 논문집 Vol.21 No.2

Limestone-calcined clay-Cement (LC3) concrete provides a solution for sustainability, durability, and profitability of concrete industry. This study shows experimental studies of the macro properties (residual compressive strength), the meso properties (mesoscopic images), and micro properties (thermogravimetric (TG) analysis, X-ray powder diffraction (XRD), FTIR spectra, Raman spectra, Mercury intrusion porosimetry, and SEM) of LC3 paste with various mixtures and at high elevated temperatures (20 ℃, 300 ℃, 550 ℃ and 900 ℃). We find (1) Regarding to macro properties, LC3 cementitious materials are at a disadvantage in compressive strength when the temperature is higher than 300 ℃. (2) Regarding to meso properties, when the temperature reached 550 ℃, all samples generated more meso cracks. (3) Regarding to micro properties, first, as the substitution amount increases, its CH content decreases significantly; second, at 900 ℃, for samples with calcined clay, a large amount of gehlenite crystalline phase was found; third, at elevated temperatures (20 ℃, 300 ℃, 550 ℃ and 900 ℃), there is a linear relationship between the residual compressive strength and the cumulative pore volume; fourth, at 900 °C, a large amount of dicalcium silicate was generated , and damage cracks were more pronounced. The experimental results of this study are valuable of material design of fire resistance of LC3 concrete.

Research on a Signal Analysis Method based on Wavelet Theory and Approximate Entropy Algorithm

Xiaoyong Yu 보안공학연구지원센터 2016 International Journal of Future Generation Communi Vol.9 No.8

The vibration signal is one of the significant signals that reflects the fault. In allusion to the shortcomings of traditional signal analysis method in the high-frequency and non-stationary signal analysis, the wavelet theory and approximate entropy algorithm are introduced into the signal analysis in order to propose a new vibration signal analysis (WTAEAVSA) method in this paper. In the proposed WTAEAVSA method, the wavelet transform technology is used to reduce the noise and decompose the low and high frequency vibration signal in order to obtain the signal characteristics of different frequency bands. Then the approximate entropy algorithm is used to determine the complexity and irregular degree of vibration signal in the different scale and different frequency band, so as the non-stationary characteristics of vibration signal are extracted. At last, some simulated signals with time-domain and frequency-domain from the normal signal are used to test the characteristics of the proposed WTAEAVSA method. The simulation results show that the proposed WTAEAVSA method can extract the characteristic vector from vibration signal, visually and sharply reflect the changes of the mechanical states.

On Full Diversity Space–Time Block Codes With Partial Interference Cancellation Group Decoding

Xiaoyong Guo,Xiang-Gen Xia IEEE 2009 IEEE transactions on information theory Vol.55 No.10

<P>In this paper, we propose a partial interference cancellation (PIC) group decoding strategy/scheme for linear dispersive space-time block codes (STBC) and a design criterion for the codes to achieve full diversity when the PIC group decoding is used at the receiver. A PIC group decoding decodes the symbols embedded in an STBC by dividing them into several groups and decoding each group separately after a linear PIC operation is implemented. It can be viewed as an intermediate decoding between the maximum likelihood (ML) receiver that decodes all the embedded symbols together, i.e., all the embedded symbols are in a single group, and the zero-forcing (ZF) receiver that decodes all the embedded symbols separately and independently, i.e., each group has and only has one embedded symbol, after the ZF operation is implemented. The PIC group decoding provides a framework to adjust the complexity-performance tradeoff by choosing the sizes of the information symbol groups. Our proposed design criterion (group independence) for the PIC group decoding to achieve full diversity is an intermediate condition between the loosest ML full rank criterion of codewords and the strongest ZF linear independence condition of the column vectors in the equivalent channel matrix. We also propose asymptotic optimal (AO) group decoding algorithm which is an intermediate decoding between the MMSE decoding algorithm and the ML decoding algorithm. The design criterion for the PIC group decoding can be applied to the AO group decoding algorithm because of its asymptotic optimality. It is well-known that the symbol rate for a full rank linear STBC can be full, i.e., <I>nt</I>, for <I>nt</I> transmit antennas. It has been recently shown that its rate is upper bounded by 1 if a code achieves full diversity with a linear receiver. The intermediate criterion proposed in this paper provides the possibility for codes of rates between <I>nt</I> and 1 that achieve full diversity with the PIC group decoding. This therefore provides a complexity-performance-rate tradeoff. Some design examples are given.</P>

A numerical and effective method for the contact stress calculation of elliptical partial slip

Xiaoyong Li,Liang Liang,Shijing Wu 대한기계학회 2015 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.29 No.2

A general elliptical Hertzian contact, such as a ball rolling in a non-conforming groove or two non-orthogonal cylinders, is a universalphenomenon in engineering. A partial elliptical contact is formed by contact bodies under a normal force and a transverse force that isinsufficient to cause complete sliding. A computational model based on the semi-analytical method is established to calculate the vonMises stress distribution. Furthermore, a parametric study on factors influencing the location of the maximum von Mises stress point,such as the coefficient of friction and stick zone ratio, is conducted. Results show that the location of the maximum von Mises stresspoint depends on the coefficient of friction f and stick zone ratio c. The von Mises stress increases significantly with the increasing coefficientof friction f. Moreover, the maximum von Mises stress point tends to occur at a subsurface when the stick ratio c increases.

Optimization of Hot Working Parameters of As-Forged Nitinol 60 Shape Memory Alloy Using Processing Maps

Xiaoyong Shu,Shiqiang Lu,Kelu Wang,Guifa Li 대한금속·재료학회 2015 METALS AND MATERIALS International Vol.21 No.4

The hot deformation behavior of as-forged Nitinol 60 alloy (60 wt% Ni, 40 wt% Ti) was studied over the ranges of temperature, 650-850 °C, and strain rate, 0.01-1 s-1, using isothermal constant strain rate compression tests in a Gleeble-3500 simulator. The processing maps, based on the dynamic materials model, were developed to optimize the hot working parameters. The results show that the deformation parameters have a marked effect on the power dissipation efficiency and the instability parameter. A single unstable region (650-775 °C, 0.037-1 s-1), associated with flow localization and/or adiabatic shear, is detected from the processing map. This should be avoided in hot working process. The optimized hot working conditions correspond to 680-790 °C, 0.01- 0.025 s-1 with peak efficiency of 0.45 at 720 °C, 0.01 s-1, and 820-850 °C, 0.1-1 s-1 with peak efficiency of 0.5 at 850 °C, 1 s-1. Microstructure observations indicate that the main deformation mechanism of optimized domains involves dynamic recrystallization.

Hysteretic Behavior of Reinforced Concrete Columns Confined By Square Steel Tubes.

Xiaoyong Wang(왕소용),Sumei Zhang(장수메이),Lee, Han-Seoung(이한승) 한국콘크리트학회 2006 한국콘크리트학회 학술대회 논문집 Vol.2006 No.5

Resilience-Oriented Performance Assessment Method for Road-Traffic System: A Case Study in Beijing, China

Xiaoyong Ni,Toshihiro Osaragi,Hong Huang,Ruiqi Li,Anying Chen 대한토목학회 2021 KSCE Journal of Civil Engineering Vol.25 No.10

The performance of an urban road-traffic system is affected by many factors, such as the average traffic demand, and the network structure, etc. At the same time, natural disasters, abnormal traffic volume and man-made accidents can result in disturbances which also influence the performance of the system. Resilience of an urban road-traffic system has been an emerging research field. This paper proposes a resilience-oriented performance assessment method based on a traffic flow assignment model to precisely capture the performance of an urban road-traffic system. System functionality is chosen as the key proxy for resilience, which can be calculated based on some index parameters including allocation rate of traffic flow, commuting efficiency on road sections, etc. A case study is implemented in a downtown area in Beijing, China. As to the resilience of the system when faced with huge traffic volume, the results show that the road-traffic system itself has a certain degree of absorption capacity for traffic pressure induced by huge volume. As to the resilience of the system when faced with local network failure, the results show that information dissemination of the network condition and the traffic volume are the key impact factors on system’s resilience curves.

Analysis of elliptical Hertz contact of steel wires of stranded-wire helical spring

Xiaoyong Li,Shilong Wang,Jie Zhou 대한기계학회 2014 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.28 No.7

A stranded-wire helical spring is formed of a multilayer and coaxial strand of several wires twisted together with the same direction ofspiral. Because of the multilayer structure, the wear on the local area of the steel wires’ surface is related to the elliptical contact betweenadjacent wires during working process. Based on Boussinesq potential functions and elastic half-space model, the contact area and surfacepressure of elliptical Hertz contact were investigated. Moreover, these surface contact quantities are used to expand the calculationof subsurface stress relevant to elliptical contact. It is found that the greater contact angle of two contact wires, the smaller contact areaand greater maximum contact pressure. Meanwhile, the magnitude of subsurface von Mises stress is much higher when the contact angleincreases.

A Novel Stator Hybrid Excited Doubly Salient Permanent Magnet Brushless Machine for Electric Vehicles

Xiaoyong Zhu,Ming Cheng 대한전기학회 2006 Journal of Electrical Engineering & Technology Vol.1 No.2

In this paper, a novel stator hybrid excited doubly salient permanent magnet (SHEDS-PM) brushless machine with a special magnetic bridge is proposed for the first time. The originality of this machine is purposely to add a magnetic bridge in shunt with each PM pole, which not only maintains the stator lamination in its entireness, but also amplifies the effect of DC field flux on PM flux. An equivalent magnetic circuit is presented to clarify the novelty. Based on the 2-D finite element analysis, the static characteristics of the SHEDS-PM machine, namely phase flux linkage, back-EMF, cogging torque, winding inductance and static torque are deduced. The corresponding results on a prototype machine illustrate that the proposed machine is promising for application to electric vehicles.

Ant Colony Optimization Algorithm Based on Dynamical Pheromones for Clustering Analysis

Xiaoyong Liu 보안공학연구지원센터 2014 International Journal of Hybrid Information Techno Vol.7 No.2