• The Transactions of the Korean Institute of Electrical Engineers C
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• v.54 no.5
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• pp.198-205
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• 2005

Many precedent investigations hate been made for the reliable assessment of the insulation state of large power apparatus for which partial discharge detection is one of tile plausible way. In this work, experimental investigations have been carried out to make the comparison on the PD(partial discharge) pattern analysis related to the five different types of artificial defects such as SFMP (Single Free Moving Particle), MFMP (Multi Free Moving Particle), Void, CFP (Conductor-Fixed Protrusion), EP (Enclosure Protrusion). For each PD pattern, PD detection has been done by tee different types of PD sensors such as HFCT(High Frequency Current Transformer), AE(Acoustic Emission) and UHF(Ultra High Frequency). And, in addition, frequency spectrum by the UHF sensor has been also made for each defect respectively. As a result, it is observed that the possibility of obtaining PD pattern based on PRPD(Phase Resolved Partial Discharge) in connection with the defects tinder investigation is dependant on the type of the sensor while the spectrum analysis is always successful to be achieved for every defect. Therefore, it could be suggested that the nature of PD source can be identified more distinctively when the conventional PRPDA is combined with spectrum analysis.

• Journal of the Korea Institute of Building Construction
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• v.20 no.4
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• pp.357-365
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• 2020

While numbers of apartment housing are continually rising in the domestic housing construction industry, apartment contractors are currently developing plane models, upgrading facilities, and relevant technology, and investing much efforts to meet the higher demands of consumers. However, the construction process of apartment housing involves the intricate properties of the construction industry such as materials, workforce, equipment, weather, and unpredictable situations. If any of these factors becomes discordant and results in interference and interruption of the construction process, then defects, both functional and aesthetic, are likely to occur due to errors in the plan of industry organizers and constructors. Therefore, this research identifies the types of defects in an apartment construction project and analyzes their relative importance. Firstly, this research reviews the previous research trends and will reduce the needs of this research. Afterward, defect repair costs corresponding to the different defect types are calculated by applying results of the research and performing frequency analysis on defect types included in 'Tenant preliminary research' on apartments constructed by Company A. As a result of analyzing the importance of defect type, the top six activities, including tile, floor, paper hanging, PL window, cabinetry, and kitchen cabinet, are found to be of high importance, and the top six activities in question need of repair and management of defects first. The results of this study will help establish a plan to initially respond to such problems as refusal to move in and filing a defect suit against delay in repairing defects.

• Transactions of Materials Processing
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• v.11 no.2
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• pp.147-154
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• 2002

The tension levelling Process is Performed to elongate the strip plastically In combination of tensile and bending strain so that all longitudinal fibers In the strip have an approximately equal amount ofn length and undesirable strip shapes are corrected to the flat shape. Thus paper is concerned with a simulation of the tension levelling process based on the analysis of tile unit model for the tension leveller. Analysis technique such as the sequential analysis of the unit model is suggested and verified with the assembly analysis of the unit model for the effective arts economic analysis of the full set of the tension leveller. Analysis of the full tension levelling Process using sequential unit models Is carried out for steel strips with the shape defect and provides the effect of the intermesh and optimum amount of the intermesh in tension levelling process.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2006.04a
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• pp.381-388
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• 2006

A porous medium is composed of solids, fluids, and gas which have different physical and chemical properties. In addition, these constituents have a relative velocity between each other. So far, in order to analyze porous media using finite element method, Lagrangian or Eulerian method has been used. However, the numerical analyses for porous media have a defect that the methods do not describe the movements of constituents. In this paper, numerical analysis for unsaturated porous media was performed in frame of ALE method which has advantages of Lagrangian and Eulerian. Namely, the Lagrangian description was used in solid phase, and the Eulerian description was used in fluid or gas phase in a porous medium Then the relationship between each other was controlled by the convective term in ALE method. Finally, the numerical results of ALE were compared with tile results of Lagrangian analysis.

• Proceedings of the KSR Conference
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• 2001.05a
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• pp.162-169
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• 2001

There are many EMU lines in korea. But only one type has been applied to passenger side door. This type is so called "Pocket sliding type". This type has some week points. To begin with, it is not good for decreasing the noisy form the outside of carbody. And the second time, if some obstacles are put between sliding door, only driver can operate re-open door switch manually ill driver's cab. This type is so dangerous for passengers. So many people want to the new door type that have no defect. KRRI joined forces with ANT corporation for pneumatic plug door system. This type will be good for decreasing the noisy, passenger′s safe. The project was started at the last year on November and will be finished on June, this year In this paper, we will deal with the role of cylinder, planetary gear, door control unit, dynamic mechanism, and the report of FEM, type test. This paper will contribute to tile electric motor control plug door system.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2002.05a
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• pp.81-85
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• 2002

Through the questionnaire, I analyzed the merit, the defect and the solution of problems of the lecture using the Video Lecturing System. In the paper, we present that the Video Lecturing is a substitute tracking method by demonstrating the superiority of it. For tile purpose of this, I compared and analyzed the Video Lecturing with the general lecture from the viewpoint of the class satisfaction and the effectiveness through the results of the questionnaire obtained by students who took the Video Lecturing class.

• Journal of the Korean Society for Nondestructive Testing
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• v.20 no.6
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• pp.555-561
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• 2000

The remote field eddy current (RFEC) inspection was performed on the ductile cast iron pipes with nominal outer diameter of 100mm, which were machined with various shapes and sizes of defects. Ductile cast iron pipes which are used as water supply pipe have the non-uniform thickness and asymmetric cross section due to relatively high degree of allowable errors during the manufacturing processes. These characteristics of ductile cast in pipes cause the long range background noises in RFEC signals along the pipe. In this study, tile machined defects in pipes were effectively classified by the moving window average (MWA) method which eliminated the long-range noise. The voltage plane polar plots (VPPP) method was used to quantitatively evaluate the depth and circumferential degree of defects. The VPPP signatures showed that the angle between defect signature and the normalized in-phase component on the VPPP is linear to the depth of defects. The nondestructive RFEC technique proved to be capable of quantitatively evaluating the machined defects of underground water supply pipe.

• Journal of the Optical Society of Korea
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• v.14 no.2
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• pp.163-169
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• 2010

Novel wafer-level fabrication of a glass ball-lens is realized for optoelectronic applications. A Pyrex wafer is bonded to a silicon wafer and cross-cut into a square-tile pattern, followed by wet-etching of the underlying silicon. Cubes of Pyrex on the undercut silicon are then turned into ball shapes by thermal reflow, and separated from the wafer by further etching of the silicon support. Radial variation and surface roughness are measured to be less than ${\pm}3\;{\mu}m$ and ${\pm}1\;nm$, respectively, for ball diameter of about $500\;{\mu}m$. A surface defect on the ball that is due to the silicon support is shown to be healed by using a silicon-optical-bench. Optical power-relay of the ball lens showed the maximum efficiency of 65% between two single-mode fibers on the silicon-optical-bench.

• Proceedings of the KIEE Conference
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• 2004.07d
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• pp.2580-2582
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• 2004

In this paper, a Neural Network(NN) based approach for classification of two dimensions images. The proposed algorithm is able to apply in the actual industry. The described diagnostic algorithm is presented to defect surface failures on tiles. A way to get data for a digital image process is several kinds of it. The tiles are scanned and the digital images are preprocessed and classified using neural networks. It is important to reduce the amount of input data with problem specific preprocessing. The auto-associative neural network is used for feature generation and selection while the probabilistic neural network is used for classification. The proposed algorithm is evaluated experimentally using one hundred of the real tile images. Sample image data to preprocess have histogram. The histogram is used as input value of probabilistic neural network. Auto-associative neural network compress input data and compressed data is classified using probabilistic neural network. Classified sample images are determined by human state. So it is intervened human subjectivity. But digital image processing and neural network are better than human classification ability. Therefore it is very useful of quality control improvement.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.10A
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• pp.1205-1214
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• 2004

For tile physical defects occurring in CMOS circuits which are not handled well by voltage-based testing, current testing is remarkable testing technique. Fault models based on defects must accurately describe the behaviour of the circuit containing the defect. In this paper, An efficient collapsing algorithm for fault models often used in current testing is proposed. Experimental results for ISCAS benchmark circuits show the effectiveness of the proposed method in reducing the number of faults that have to be considered by fault collapsing and its usefulness in various current based testing models.