• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.8
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• pp.181-189
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• 2019

An aircraft power distribution device distributes and controls the power generated by the generator and provides overcurrent protection. There are many defect phenomena that make AC power distribution impossible during flight, which poses a problem in because some electronic equipment cannot be operated. We describe a process of deriving the root cause of defects by using vibration testing equipment to simulate the vibration conditions during aircraft flight, which result in defects. The results show that the cause of the defect is internal wiring damage caused by the vibration of the contactor of the AC power distribution device. Therefore, the shape of the contactor was improved to solve this problem. We also improved the test procedure by performing defect detection tests using vibration testing equipment to detect a faulty contactor. As a result of the improvements, a component certification test and flight test proved that the defect phenomena of the AC electrical master box were improved.

• Journal of the Korean Society for Nondestructive Testing
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• v.35 no.1
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• pp.25-30
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• 2015

A wind turbine blade is an important component in wind-power generation, and is generally exposed to harsh environmental conditions. Ultrasonic inspection is mainly used to inspect such blades, but it has been difficult to quantify defect sizes in complicated composite structures. Recently, active infrared thermography has been widely studied for inspecting composite structures, in which thermal energy is applied to an object, and an infrared camera detects the energy emitted from it. In this paper, a calibration method for active optical lock-in thermography is proposed to quantify the size. Inclusion, debonding and wrinkle defects, created in a wind blade for 100 kW wind power generation, were all successfully detected using this method. In particular, a ${\phi}50.0mm$ debonding defect was sized with 98.0% accuracy.

• Journal of Internet of Things and Convergence
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• v.9 no.2
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• pp.61-69
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• 2023

In recent years, due to heightened environmental awareness, Electric Power Steering (EPS) has been increasingly adopted as the steering control unit in manufactured vehicles. This has had numerous benefits, such as improved steering power, elimination of hydraulic hose leaks and reduced fuel consumption. However, for EPS systems to respond to actions, sensors must be employed; this means that the consistency of the sensor's linear variation is integral to the stability of the steering response. To ensure quality control, a reliable method for detecting defects and assessing linearity is required to assess the sensitivity of the EPS sensor to changes in the internal design characters. This paper proposes a data-driven defect and linearity assessment monitoring system, which can be used to analyze EPS component defects and linearity based on vehicle speed interval division. The approach is validated experimentally using data collected from an EPS test jig and is further enhanced by the inclusion of a Graphical User Interface (GUI). Based on the design, the developed system effectively performs defect detection with an accuracy of 0.99 percent and obtains a linearity assessment score at varying vehicle speeds.

• Journal of Advanced Marine Engineering and Technology
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• v.12 no.2
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• pp.35-45
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• 1988

In this paper an experimental review of condition monitoring method using time domain vibration signals and statically measured wave forms of a multi-components damaged ball bearing is presented first time. Many investigators studied already about vibration characteristics of a single point damaged ball bearing but they did not make efforts to verify vibration phenomena of a multi-components damaged one. Even in case of a tripple components damaged (i.e, outer race, inner race and rolling element) one, the high frequency resonance technique (HERT) and the displacement time domain technique can be also used for its fault detection. According to experimental results undertaken a static displacement measuring method, the defect locations of components can be proposed confidently with simple calculation of the rotating angles of each component.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.2005-2006
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• 2011

Due to the advantages of small sizes, more I/O ports, etc., Ball Grid Array (BGA) has been used in the production of printed circuit board (PCB). However, BGA voids can degrade the performance of the board and cause failure. To automatically detect the voids in X-ray image, a novel blob filter that makes use of the local image gradient magnitude is proposed in this paper. The utilization of the local image gradient magnitude makes the proposed filter invariant to the image brightness, void shape, void position, and component interference. Furthermore, different sizes of box filters are employed to analyze the image in multi-scale, and as a result, the proposed blob filter is robust to void size. Experimental results show that the proposed method can obtain void detection accuracy up to 96.104% while keep low false ratio.

• Journal of the Korean Society for Nondestructive Testing
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• v.33 no.6
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• pp.519-523
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• 2013

A steam generator (SG) tube is an important component of a nuclear power plant (NPP). It works as a pressure boundary between the primary and secondary systems. The integrity of a SG tube can be assessed by an eddy current test every outage. The eddy current technique(adopting a bobbin probe) is currently the main technique used to assess the integrity of the tubing of a steam generator. An eddy current signal analyst for steam generator tubes continuously analyzes data over a given period of time. However, there are possibilities that the analyst conducting the test may get tired and cause mistakes, such as: missing indications or not being able to separate a true defect signal from one that is more complicated. This error could lead to confusion and an improper interpretation of the signal analysis. In order to avoid these possibilities, many countries of opted for automated analyses. Axial ODSCC (outside diameter stress corrosion cracking) defects on the tubes of OPR1000 steam generators have been found on the tube that are in contract with tube support plates. In this study, automated analysis software called CDS (computer data screening) made by Zetec was used. This paper will discuss the results of introducing an automated analysis system for an axial ODSCC on the tubes of an OPR1000 steam generator.

• Journal of the Korean Society for Precision Engineering
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• v.22 no.1
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• pp.53-60
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• 2005

The wire rope of container crane is a important component to container transfer system and is used in a myriad of various applications such as elevator, mine hoist, construction machinery, and so on. If it happen wire rope failures in operating, it may lead to the safety accident and economic loss, which is productivity decline, competitive decline of container terminal, etc. To solve this problem, we developed the active and portable wire rope fault detecting system. The developed system consists of three parts that are the fault detecting, signal processing, and remote monitoring part. All detected signal has external noise or disturbance according to circumstances. Therefore we applied to discrete wavelet transform to extract a signal from noisy data that was used filter. As experimental result, we can reduce the expense for container terminal because of extension of exchange period of wire rope for container crane and this system is possible to apply in several fields to use wire rope.

• Journal of Korea Society of Industrial Information Systems
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• v.26 no.6
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• pp.11-16
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• 2021

In this paper, a quality inspection system was developed to identify the defective assembly of connectors used in automobile wiring. For waterproof connectors, an internal seal must be inserted for waterproofing. However, there are cases where it is omitted or double-inserted during production. An automatic inspection jig was designed using photosensors and touch switches to classify good and bad connector components. In the case of the existing visual inspection, 6,400 connectors were inspected when 5 people inspected for 8 hours. However, when using the inspection jig developed under the same conditions, 20,000 pieces were inspected. In other words, the productivity is greatly improved compared to the conventional visual inspection.