• Transactions of the Korean Society of Mechanical Engineers
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• v.16 no.4
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• pp.707-722
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• 1992

Fracture of a cutting tool is one of the most serious problems in machining systems. Therefore, several methods have been proposed so far to detect cutting tool fracture. However, most of them have some problems from the viewpoint of practical applications. In this study, the feasibility of using acoustic emission and cutting force signals for the detection of massive tool breakages as well as small fracture of cutting tools were investigated. Turning experiments were performed using conventional carbide inset tools under realistic cutting conditions and the SM45C steel and heat treated SM45C steel were used as a workpiece. And the sensitivities of the AE and cutting force signals to the fracture of cutting tools were illustrated. Finally, a detection algortithm for the fracture of cutting tools was developed through the analysis of these dual signals in the several types of tool fracture.

• Journal of IKEEE
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• v.26 no.2
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• pp.265-270
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• 2022

This paper proposes the detection algorithm for switch open fault of asymmetric 6-phase PMSM based on stationary reference frame dq-axis currents. In this paper, target motor has an asymmetric structure in which two upper three windings have an electrical phase difference of 30° and a neutral point is separated. As a result, dual 3-phase PWM inverters and the detection techniques due to open failures of switch are definitely required. In this paper, the dual dq-axis current control method is used for driving the asymmetric 6-phase PMSM and the open fault switch should be detected by using variable all pass filter and low pass filter in order to detect the current amplitude. The effectiveness and usefulness of the proposed method is verified by several experiments.

• Proceedings of the Korea Information Processing Society Conference
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• 2022.11a
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• pp.455-455
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• 2022

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.9
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• pp.1802-1808
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• 2009

A fault detection observer with finite time convergence characteristics(FT_FDO) is proposed and applied to a fault detection isolation system for a dynamic control system. The FT_FDO is a kind of dual state-observer scheme that provides with the state estimates insensitive to a specified fault and the corresponding fault estimate. The state estimates are processed to get the residual that will be logically compared with other residuals to detect and isolate the fault of interest, and the fault estimate may be used for fault compensation. The FDIS employing the FT_FDOs can be considered to be a multiple observer schemes(MOS) in which FT_FDOs are parallelly driven to generate a set of residuals to be compared each other. Due to the finite time convergence characteristics of the FT_FDO, the predetermined detection delay can be considered in the design stage of FDIS so that any fault of interest can be detected and identified in that time. It evidently resolves a well known difficulty of threshold selection owing to the transient responses of the fault detection observers(FDO) employed in FDIS. An FDIS is constructed for instruments(2-sensor, 1-actuator) in an inverted pendulum control system, and simulations are performed to show the performance of the FDIS and fault tolerant control system.

• Journal of the Korean Society of Radiology
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• v.16 no.5
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• pp.537-543
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• 2022

The purpose of this simulation study was to evaluate the possibility of pancreas detection through effective atomic number information using dual-energy computed tomography(CT). The effective atomic number of 10 tissue-equivalent materials were estimated through stoichiometric calibration. For stoichiometric calibration, HU values at low-energy (80 kV) and high-energy (140 kV) for 10 tissue-equivalent materials were used. Based on this method, the effective atomic number image of the tissue-equivalent material was extracted through an iterative algorithm. According to the results, the attenuation ratio in accordance with the effective atomic number was estimated to have an R² value of 0.9999, and the effective atomic number of Pancreas, Water, Liver, Blood, Spongiosa, and Cortical bone was overall within 1% accuracy compared to the theoretical value. Conventional pancreatic cancer examination uses a contrast medium, so there is a possibility of potential side effects of the contrast medium. In order to solve this problem, it is thought that it will be possible to contribute to an accurate and safe examination by extracting the effective atomic number using dual-energy CT without contrast enhancement. Based on this study, future research will be conducted on the detection of pancreatic cancer using the HU value of pancreatic cancer based on clinical images.

• IMMUNE NETWORK
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• v.9 no.6
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• pp.243-247
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• 2009

In this study, we report the development of a new dual reporter vector system for the analysis of promoter activity. This system employs green fluorescence emitting protein, EGFP, as a reporter, and uses red fluorescence emitting protein, DsRed, as a transfection control in a single vector. The expression of those two proteins can be readily detected via flow cytometry in a single analysis, with no need for any further manipulation after transfection. As this system allows for the simultaneous detection of both the control and reporter proteins in the same cells, only transfected cells which express the control protein, DsRed, can be subjected to promoter activity analysis, via the gating out of all un-transfected cells. This results in a dramatic increase in the promoter activity detection sensitivity. This novel reporter vector system should prove to be a simple and efficient method for the analysis of promoter activity.

• Journal of Computing Science and Engineering
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• v.8 no.1
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• pp.17-24
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• 2014

In this paper, we propose a new implementation of a failure detector. The implementation uses a dual model of heartbeat and interaction. First, the heartbeat model is adopted to shorten the detection time, if the detection process does not receive the heartbeat message in the expected time. The interaction model is then used to check the process further. The expected time is calculated using the exponential smoothing method. Exponential smoothing can be used to estimate the next arrival time not only in the random data, but also in the data of linear trends. It is proven that the new detector in the paper can eventually be a perfect detector.

• Journal of the Korean Society for Precision Engineering
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• v.26 no.11
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• pp.55-61
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• 2009

The wall thinning defect of nuclear power pipe is mainly occurred by the affect of the flow accelerated corrosion (FAC) of fluid. This type of defect becomes the cause of damage or destruction of in carbon steel pipes. Therefore, it is very important to measure defect which is existed not only on the welding part but also on the whole field of pipe. This study use dual-beam Shearography, which can measure the out-of-plane deformation and the in-plane deformation by using another illuminated laser beam and simple image processing technique. And this study proposes Infrared thermography, which is a two-dimensional non-contact nondestructive evaluation that can detect internal defects from the thermal distribution by the inspection of infrared light radiated from the object surface. In this paper, defect of nuclear power pipe were, measured using dual-beam shearography and infrared thermography, quantitatively evaluated by the analysis of phase map and thermal image pattern.

• Korean Journal of Optics and Photonics
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• v.15 no.3
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• pp.229-233
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• 2004

We propose a novel scheme to suppress the multiple-access interference(MAI) in coherent optical CDMA systems. This is based on a differential detection using the dual-control NOLM. For an experimental demonstration, two encoded channels we constructed and decoded. These decoded signals are sent to the dual-control NOLM and a high autocorrelation peak with suppressed MAI at the output of the NOLM is observed. Signal-to-interference ratio is improved by 7 ㏈.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.44 no.3
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• pp.256-265
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• 2016

Software based fault tolerance techniques are designed to allow a system to tolerate software faults in the system. Fault tolerance techniques are divided into two groups : software based fault tolerance techniques and hardware based fault tolerance techniques. We need a proper design method according to characteristics of the system. In this paper, the concepts of software based fault tolerance techniques for Dual Flight Control Computer are described. For software based fault tolerance design, we classified software failure, designed a way for failure detection and the way of recovery. Eventually the effectiveness of software based fault tolerance techniques was verified through the Software Test Environment(STE).