• 전기학회논문지
• /
• 제59권10호
• /
• pp.1882-1888
• /
• 2010

It is widely known that ESA(Electric Signature Analysis) method is very useful one for fault diagnosis of an induction motor. Online fault diagnosis system of induction motors using LabVIEW is proposed to detect the fault of broken rotor bars and shorted turns in stator. This system is not model-based system of induction motor but LabVIEW-based fault diagnosis system using FFT spectrum of stator current in faulty motor without estimating of motor parameters. FFT of stator current in faulty induction motor is measured and compared with various reference fault data in data base to diagnose the fault. This paper is focused on to predict and diagnose of the health state of induction motors in steady state. Also, it can be given to motor operator and maintenance team in order to enhance an availability and maintainability of induction motors. Experimental results are demonstrated that the proposed system is very useful to diagnose the fault and to implement the predictive maintenance of induction motors.

• 한국구조물진단유지관리공학회 논문집
• /
• 제7권2호
• /
• pp.239-246
• /
• 2003

In the PCA Load Contour Method, the biaxial bending design coefficient of columns(${\beta}$) is based on the equivalent rectangular stress block (RSB). And coefficient of ${\beta}$ estimates the reinforcement index to be a influencing parameter on biaxial moment strength of RC columns without considering the arbitrary condition of bar arrangement. The experimental results of high strength concrete (HSC) columns subjected to combined axial load and biaxial bending moment were compared to the analysis results of RSB method. As result, the accuracy of RSB method is still acceptable for HSC columns and, as the reinforcement is placed densely in each corner of column section, the ${\beta}$ is decreased.

• 한국구조물진단유지관리공학회 논문집
• /
• 제7권2호
• /
• pp.209-218
• /
• 2003

The analytical studies included nonlinear finite element analysis of split-tee connection details subjected to axial load and lateral load. A three-dimensional model of the connections between CFT columns and H-beams has been developed. Both initial geometrical imperfections and residual stresses are taken into consideration. A geometrically nonlinear load-displacement analysis of the structure containing the imperfection is then performed, using the Riks method. Analytical results are compared with existing experimental results. Extensive parametric analyses are carried out to investigate the relation of the connections between CFT columns and H-beam to various parameters such as the axial load, column width-thickness ratio, and split-tee thickness.

• 한국구조물진단유지관리공학회 논문집
• /
• 제7권2호
• /
• pp.193-199
• /
• 2003

This paper presents the results of an experimental research project on 7 Super Deck Plates with continuous or simple beam types. The test parameters included the distance of truss, depth of deck plate and the type of beam. The test results are as follows ; When thickness of deck plate was increased, maximum strength was improved When the distance of truss bar was reduced from 20cm to 15cm, the mean value of maximum load was increased to 1.21 times. Continuous beam shown superior to simple beam, such as 5.03 times high strength, low deflection at yield point.

• Communications for Statistical Applications and Methods
• /
• 제13권1호
• /
• pp.191-204
• /
• 2006

This paper develops a Bayesian method to derive the optimal sequential preventive maintenance(PM) policy by determining the PM schedules which minimize the mean cost rate. Such PM schedules are derived based on a general sequential imperfect PM model proposed by Lin, Zuo and Yam(2000) and may have unequal length of PM intervals. To apply the Bayesian approach in this problem, we assume that the failure times follow a Weibull distribution and consider some appropriate prior distributions for the scale and shape parameters of the Weibull model. The solution is proved to be finite and unique under some mild conditions. Numerical examples for the proposed optimal sequential PM policy are presented for illustrative purposes.

• 한국구조물진단유지관리공학회 논문집
• /
• 제3권4호
• /
• pp.145-153
• /
• 1999

The major objective of this study is to investigate experimentally the shear strengthening effect of carbon fiber sheets upon reinforced concrete deep beam and shear failure behavior variation of reinforced concrete deep beam strengthened by carbon fiber sheets. Tests are carried out with 6 specimens were shear failure at first loading tests, and with parameters including the types of shear strengthening of carbon fiber sheets (I type, S type, U type), and plies of sheets (2 ply and 1 ply). From the results of test, analyzed load-deflection of midspan, strain variation of main bars and transverse reinforcement, maximum load capacity of strengthened specimens, and compared with the previous test results.

• 한국구조물진단유지관리공학회 논문집
• /
• 제1권2호
• /
• pp.123-130
• /
• 1997

The effect of experimental factors on the Freeze-Thaw durability in the High Strength Concrete has been analyzed and investigated with [DESIGN of EXPERIMENT: L16). The Experimental parameters included the type of aggregate and mixer, the conditions of aggregates, and the difference of mixing temperature, procedure and placing, etc. It is aim of this study to provide the fundamental data on the effect of various factors on the frost resistance of high strength concrete for the practical use and research data accumulation of durability inspection. The results of this experiment indicate that the freeze-thaw durability of high strength concrete is markedly affected by the coarse aggregate source, mixing temperature and curing conditions.

• Animal cells and systems
• /
• 제1권4호
• /
• pp.619-627
• /
• 1997

Maintenance of polymorphism in a two-locus system with two alleles under stabilizing selection has been tested by Monte-Carlo simulation. The effect of each allele was additive. Only gene x environment interactions and degree of genetic linkage between loci were considered. There were no other evolutionary forces acting except stabilizing selection. Fixation rates were influenced by the extent of environmental change and the degree of genetic linkage. In most cases, stabilizing selection depleted genetic variability when two loci have a lower degree of linkage (10 cM). When two loci are closely linked (0.1 cM), however, stabilizing selection promoted balanced heterozygotes in changing environments. Thus, environment-dependent selection and recombination rate are important parameters which should be incorporated into mechanisms of maintenance of genetic variability.

• 한국구조물진단유지관리공학회 논문집
• /
• 제6권2호
• /
• pp.245-253
• /
• 2002

This study was focused on the effect of concrete strength and lateral ties of concrete columns using high-strength concrete. Thirty-six concrete columns with 20cm square cross-section were tested. Experimental parameters included the concrete strength, the distribution of longitudinal bars and the volumetric ratio, yield strength, spacing of lateral ties. From the experiments, we found that: 1) the increasing rate of the strength and ductility of concrete columns caused by confinement of lateral ties was decreasing, as the concrete strength increased. 2) The high volumetric ratio and the reduction of tie spacing had a tendency to enhance the strength and improve the ductility. 3) The high-strength concrete columns required high volumetric ratio of lateral ties to maintain the proper strength and ductility. It was observed that the current AIK design code to specify the maximum tie spacing of high-strength concrete columns led to the poor strength and ductility for seismic design.

• 한국구조물진단유지관리공학회 논문집
• /
• 제6권2호
• /
• pp.203-210
• /
• 2002

In these days, High-strength steel prevails throughout the construction fields for the benefit of structural and economical aspects. But high-strength steel is used by the simple calculation of flexural capacities for the purpose of reducing flexural reinforcement. So, this paper is mainly focused on the shear behavior of high-strength steel reinforced concrete beams without stirrups comparing with normal-strength steel reinforced concrete beams. Specimens were made and tested with the experimental parameters, such as steel yield strength, reinforcement ratios and minimum shear reinforcement. The main result was that not only area but also the yield strength of flexural reinforcement should be considered to predict the shear capacities of concrete beams. In addition, the experimental results were simulated by modified compression field theory analysis program, RESPONSE 2000. A good agreement was achieved between the test results and program analyses.