• Journal of Electrical Engineering and Technology
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• v.2 no.2
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• pp.188-193
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• 2007

Magnetic contactors (MCs) are widely used in industrial equipment such as elevators, cranes and factory control rooms in order to close and open the control circuits. The reliability of MCs mainly depend on mechanical durability and international standards such as IEC 60947-4-1, which stipulates the testing method for MCs. Testing time, however, is so long in usual cases that a method of reducing testing time is required. Therefore, a temperature and voltage-accelerated life testing (ALT) method has been developed to reduce the testing time in this work. The accelerated life test data are analyzed and acceleration factors (AFs) are provided.

• Journal of the Institute of Electronics and Information Engineers
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• v.53 no.11
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• pp.130-138
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• 2016

In this paper present the real-time system parallel testing techniques for weapon systems error verification. Previously field testing equipment in the military field was using the sequential testing method to maintain. This method could not check the error verification of interference. For this reason, in this paper propose the real-time system parallel testing techniques using an embedded module instead of the sequential testing techniques which is used in the weapon system error verification. Using the embedded module mounted switching control card conduct the parallel testing and then send the result to the PC. This method is possible to increase the reliability in the weapon system error verification.

• KIISE Transactions on Computing Practices
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• v.21 no.2
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• pp.132-137
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• 2015

A real-time system is a system wherein the behavior of the system depends not only on the input but also on the timing of the input. Timed automata is a widely used model for real-time system modeling and analysis. Model-based testing is employed to check whether the system under test (SUT) works according to the model specifications by using test cases generated from models that represent software requirements. In this paper, a case study was performed applying the timed automata based testing tools, UPPAAL-TRON, UPPAAL-COVER and SYMBOLRT, to the same system. Comparison of the testing approaches and tools is then made based on the results of the case study.

• Smart Structures and Systems
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• v.14 no.6
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• pp.1055-1079
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• 2014

Substructure shake table testing is a class of real-time hybrid simulation (RTHS). It combines shake table tests of substructures with real-time computational simulation of the remaining part of the structure to assess dynamic response of the entire structure. Unlike in the conventional hybrid simulation, substructure shake table testing imposes acceleration compatibilities at substructure boundaries. However, acceleration tracking of shake tables is extremely challenging, and it is not possible to produce perfect acceleration tracking without time delay. If responses of the experimental substructure have high correlation with ground accelerations, response errors are inevitably induced by the erroneous input acceleration. Feeding the erroneous responses into the RTHS procedure will deteriorate the simulation results. This study presents a set of techniques to enable reliable substructure shake table testing. The developed techniques include compensation techniques for errors induced by imperfect input acceleration of shake tables, model-based actuator delay compensation with state observer, and force correction to eliminate process and measurement noises. These techniques are experimentally investigated through RTHS using a uni-axial shake table and three-story steel frame structure at the Johns Hopkins University. The simulation results showed that substructure shake table testing with the developed compensation techniques provides an accurate and reliable means to simulate the dynamic responses of the entire structure under earthquake excitations.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.53 no.12
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• pp.626-633
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• 2004

In this paper, we present a time domain combined field integral equation (TD-CFIE) formulation to analyze the transient electromagnetic response from three-dimensional dielectric objects. The solution method in this paper is based on the method of moments (MoM) that involves separate spatial and temporal testing procedures. A set of the RWG (Rao, Wilton, Glisson) functions Is used for spatial expansion of the equivalent electric and magnetic current densities and a combination of RWG and its orthogonal component is used as spatial testing. We also investigate spatial testing procedures for the TD-CFIE to select the proper testing functions that are derived from the Laguerre polynomials. These basis functions are also used for temporal testing. Use of this temporal expansion function characterizing the time variable enables one to handle the time derivative terms in the integral equation and decouples the space-time continuum in an analytic fashion. Numerical results computed by the proposed formulation are presented and compared with the solutions of the frequency domain combined field integral equation (FD-CFIE).

• Smart Structures and Systems
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• v.4 no.5
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• pp.667-684
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• 2008

Numerous devices exist for reducing or eliminating seismic damage to structures. These include passive dampers, semi-active dampers, and active control devices. The performance of structural systems with these devices has often been evaluated using numerical simulations. Experiments on structural systems with these devices, particularly at large-scale, are lacking. This paper describes a real-time hybrid testing facility that has been developed at the Lehigh University NEES Equipment Site. The facility enables real-time large-scale experiments to be performed on structural systems with rate-dependent devices, thereby permitting a more complete evaluation of the seismic performance of the devices and their effectiveness in seismic hazard reduction. The hardware and integrated control architecture for hybrid testing developed at the facility are presented. An application involving the use of passive elastomeric dampers in a three story moment resisting frame subjected to earthquake ground motions is presented. The experiment focused on a test structure consisting of the damper and diagonal bracing, which was coupled to a nonlinear analytical model of the remaining part of the structure (i.e., the moment resisting frame). A tracking indictor is used to track the actuator ability to achieve the command displacement during a test, enabling the quality of the test results to be assessed. An extension of the testbed to the real-time hybrid testing of smart structures with semi-active dampers is described.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.7 no.4
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• pp.49-54
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• 2012

In this paper, a software policy considering testing time and the number of errors corrected is presented. The software is tested until a specified testing time or the time to a specified number of errors are corrected, whichever comes first. The model includes the cost of error correction and software testing during the testing time, and the cost of error correction during operation. It is assumed that the length of software life cycle has no bounds, and the error correction follows an non-homogeneous Poisson process. An expression for the total cost under the policy is derived. It is shown that the model includes the previous models as special cases.

• Proceedings of the Korean Reliability Society Conference
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• 2005.06a
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• pp.69-73
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• 2005

The failure of geogrids used for soil reinforcement application can be defined as an excessive creep strain which causes the collapse of slopes and embankments. Accordingly, the lifetime is evaluated as a time to reach the excessive creep strain using two accelerated creep testing methods, time-temperature superposition(TTS) and stepped isothermal methods(SIM). TTS is a well-accepted acceleration method to evaluate creep behavior of polymeric materials, while SIM was developed in the last ten years mainly to shorten testing time and minimize the uncertainty associated with inherent variability of multi-specimen tests. The SIM test is usually performed using single rib of geogrids for temperature steps of $14^{\circ}C$ and a dwell time of 10,000 seconds. However, for multi-ribs of geogrids, the applicability of the SIM has not been well established. In this study, the creep behaviors are evaluated using multi-ribs of polyester geogrids using SIM and TTS creep procedures and the newly designed test equipment. Then the lifetime of geogrids are predicted by analyzing the failure times to reach the excessive creep strains through reliability analysis.

• Proceedings of the Korean Statistical Society Conference
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• 2002.11a
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• pp.279-285
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• 2002

In this paper we consider the problem of testing for structural changes in ARIMA models based on a cusum test. In particular, the proposed test procedure is applicable to testing for a change of the status of time series from stationarity to nonstationarity or vice versa. The idea is to transform the time series via differencing to make stationary time series. We propose a graphical method to identify the correct order of differencing.

• Proceedings of the Safety Management and Science Conference
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• 2011.04a
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• pp.451-459
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• 2011

In this paper, a software release model is presented to determine the optimum testing time with consideration of software error type. The software errors are classified into two types, major and minor errors. The software testing is continued until the Nth major error is discovered and corrected. The total cost needed before and after testing time is modeled under nonhomogeneous Poisson error correction model. Numerical examples are presented to demonstrate the results.