• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.4 s.175
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• pp.811-823
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• 2000

In design and manufacturing airframe structures which are composed of a lot of sub-assemblies and large complex profile shapes it is difficult to reduce so called hardware variations. Accordingly cost increasing factors for manufacturing airframe parts are much more than other machine parts because of the variability of fabricated details and assemlies. To improve cost and quality, accurate assembly methods and DPD techniques are proposed in this paper which are based upon using CAD/CAM techniques, the concept of KC's and the coordinated datum and index throughout the design, tooling, manufacturing and inspection. The proposed methods are applied to produce fuselage frame assemblies and related engineering aspects are described regarding the design of parts and tools in the context of concurrent digital definition. First articles and consequent mass production of frame assemblies shows a great improvement of the process capability ratio from 0.7 by the past processes to 1.0 by the proposed methods in addition to the cost reduction due to the less number of tools, reduced total assembly times and the space compaction needed by massive inventory. The need to achieve better Cpk, however, and future studies to be investigated will be addressed briefly.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2002.04a
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• pp.480-485
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• 2002

The purpose of this paper is the development of guidance algorithm for a mobile robot which is used to acquire the position and state information of the pipe defects such as crack, damage and through hole. The data used for the algorithm is the range data obtained by the range sensor which is based on an optical triangulation method. The sensor, which consists of a laser slit beam and a CCD camera, measures the 3D profile of the pipe's inner surface. After setting the range sensor on the robot, the robot is put into a pipe. While the camera and the LSB sensor part is rotated about the robot axis, a laser slit beam (LSB) is projected onto the inner surface of the pipe and a CCD camera captures the image. From the images the range data is obtained with respect to the sensor coordinate through a series of image processing and applying the sensor matrix. After the data is transformed into the robot coordinate, the position and orientation of the robot should be obtained in order to guide the robot. In addition, analyzing the data, 3D shape of the pipe is constructed and the numerical data for the defects of the pipe can be found. These data will be used for pipe maintenance and service.

• Textile Coloration and Finishing
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• v.22 no.4
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• pp.373-379
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• 2010

The laboratory inspection and analysis of several types of ropes such as edge tensile test, D/d tensile test and abrasion test were carried out in order to investigate the abrasion degradation by external damage and to obtain the fundamental data for measurement against the abrasion. PET ropes were socketed and evaluated under tensile testing. A yarn-on-yarn abrasion test machine has been developed to study the damage and failure associated with rubbing between fiber surfaces. The abrasion test method consists of sliding a length of interwrapped yarn against itself in a reciprocating fashion, either dry or immersed in liquid. It has also been adapted to measure yarn-on-yarn friction. The influence of spin finish on yarn friction and abrasion was investigated extensively. This study indicates that finish has a major effect not only on yarn performance but also on rope performance under the marine environment.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.463-464
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• 2011

Currently, different kinds of diagnosis and inspection technologies are applied to prevent the internal mechanical transformation of transformers. For example, examination of internal Partial Discharge of transformer, analysis of transformer oil gas, and measurement Frequency Response Analyzer(FRA) are used to diagnose defect. Especially, diagnosis technique through Frequency Response Analyzer(FRA) has been used and developed from 1960, when it was first introduced, till now to become an important tool to examine presence of defect and to prove quality of machines for the most electric machine producers electric power company in the world. However, diagnosis through FRA is still in introduction level in Korea and the application method for FRA is not established yet. For that reason, study about the application of domestic electric installation according to the FRA is needed. It is expected that the study play an important part in the prevention of defect due to the internal transformation of transformer by introducing measurement theory, providing measurement method, and analyzing application cases.

• The KIPS Transactions:PartB
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• v.13B no.4 s.107
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• pp.377-382
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• 2006

In this paper, two methods based on the use of morphology and pattern matching prior to detect classified defects automatically on the back light unit which is a part of display equipments are proposed. One is the template check method which detects small size defects by using closing and opening method, and the other is the block matching method which detects big size defects by comparing with four regions of uniform blocks. The TC algorithm also can detect defects on the non-uniform pattern of BLU by using revised Otsu method. The proposed method has been implemented on the automatic defect detection system we developed and has been tested image data of BLU captured by the system.

• Journal of the Korean Society for Precision Engineering
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• v.26 no.7
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• pp.112-119
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• 2009

The purpose of this study is to evaluate the evaluation of process yield performed by using Sn & Cu treatment on the surface to optimize process condition for Lead-free solder application. The materials which are used for the New Surface Treatment study are Semi-Dulling plating for high speed Sn/Cu alloy of Soft Alloy GTC-33 Pb free known as "UEMURA Method" and plating substrate is alloy 42.Especially in lead-free plating process, it is important to control plating thickness and Copper composition than Sn/Pb plating. Evaluated and controlled plating thickness $12{\pm}3um$, Copper composition $2{\pm}1%$, plating particle and visual inspection. The optimization of these parameters and condition makes it makes possible to apply Sn/Cu Lead-free solder from Sn/Pb alloy.

• Journal of the Korean Society for Nondestructive Testing
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• v.31 no.5
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• pp.508-515
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• 2011

Bovine incisor was investigated using active infrared thermography(IRT) to visualize crack on bovine teeth. An artificial crack was carefully created in bovine incisor sample by compression load of universal tensile machine. While applying a sinusoidal heat wave to the cracked bovine incisor through halogen lamp, consecutive digital infrared images was captured from the sample surface at a frequency synchronized with heat excitation. Phase information of thermal image was calculated by four-point correlation method and processed to produce the phase image of bovine incisor. This phase image showed clearly the crack on the incisor, which was hardly detected in traditional passive thermography.

• Journal of the Korean Society for Nondestructive Testing
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• v.35 no.3
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• pp.206-214
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• 2015

In this study, low-velocity impact damage (LVID) in glass fiber reinforced plastic (GFRP) was investigated using pulse thermography (PT) and lock-in thermography (LIT) techniques. The main objective of this study was to evaluate the detection performance of each technique for LVID in GFRP. Unidirectional and cross-ply GFRPs were prepared with four energy levels using a drop weight impact machine and they were inspected from the impact side, which may be common in actual service conditions. When the impacted side was used for both inspection and thermal loading, results showed that the suggested techniques were able to identify the LVID which is barely visible to the naked eye. However, they also include limitations that depend on the GFRP thickness at the location of the delamination produced by the lowest impact energy of five joule.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.21 no.11
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• pp.1862-1870
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• 1997

A fast and precise technique to measure 3-dimensional coordinates of an object is proposed. It is essential to take the 3-dimensional measurements of the object in design and inspection. Using this developed system a surface model of a complex shape can be constructed. 3-dimensional world coordinates are projected onto a camera plane by the perspective transformation, which plays an important role in this measurement system. According to the shape of the object two measuring methods are proposed. One is rotation of an object and the other is translation of measuring unit. Measuring speed depending on image processing time is obtained as 200 points per second. Measurement resolution i sexperimented by two parameters among others; the angle between the laser beam plane and the camera, and the distance between the camera and the object. As a result of these experiments, it was found that measurement resolution ranges from 0.3mm to 1.0mm. This constructed surface model could be used in manufacturing tools such as rapid prototyping machine.

• Journal of the Korean Society of Industry Convergence
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• v.23 no.2_2
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• pp.163-171
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• 2020

The condition of tire tread is a key parameter closely related to the driving safety of a vehicle, which affects the contact force of the tire for braking, accelerating and cornering. The major factor influencing the contact force is tread wear, and the more tire tread wears out, the higher risk of losing control of a vehicle exits. The tire tread condition is generally checked by visual inspection that can be easily forgotten. In this paper, we propose the intelligent tire (iTire) system that consists of an acceleration sensor, a wireless signal transmission unit and a tread classifier. In addition, we also presents classification algorithm that transforms the acceleration signal into the frequency domain and extracts the features of several frequency bands as inputs to an artificial neural network. The artificial neural network for classifying tire wear was designed with an Multiple Layer Perceptron (MLP) model. Experiments showed that tread wear classification accuracy was over 80%.