• Journal of Ocean Engineering and Technology
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• v.23 no.2
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• pp.81-86
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• 2009

Infrared thermography was used to determine the location, size, and depth of defects under the surface of M.C nylon. Defects were created in a specimen by back-drilling circular holes. These defects were located at the maximum temperature difference that occurred. The sizes of the defects could be calculated by means of the full width at half of the maximum temperature difference. The depth of a defect could be calculated by the peak time and the maximum temperature difference. The maximum temperature difference between a defect and normal part was decreased with the depth of the defect. And the peak time also slowly appeared with the depth of the defect.

• Journal of Institute of Control, Robotics and Systems
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• v.19 no.12
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• pp.1094-1098
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• 2013

AVI (Automatic Vision Inspection) systems automatically detect defect features and measure their sizes via camera vision. Defect detection is not an easy process because of noises from various sources and optical distortion. In this paper the acquired images from a TFT panel are enhanced with the adoption of an HVS (Human Visual System). A human visual system is more sensitive on the defect area than the illumination components because it has greater sensitivity to variations of intensity. In this paper we modified an MTF (Modulation Transfer Function) in the Wavelet domain and utilized the characteristics of an HVS. The proposed algorithm flattens the inner illumination components while preserving the defect information intact.

• Smart Structures and Systems
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• v.23 no.1
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• pp.71-79
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• 2019

In general, it may be advantageous to measure the pressure pulsation near a valve to detect a valve defect in a linear compressor. However, the acceleration signals are more advantageous for rapid classification in a mass-production line. This paper deals with the performance improvement of fault classification using only the compressor-shell acceleration signal based on the relation between the refrigerant pressure pulsation and the shell acceleration of the compressor. A transfer function was estimated experimentally to take into account the signal noise ratio between the pressure pulsation of the refrigerant in the suction pipe and the shell acceleration. The shell acceleration signal of the compressor was modified using this transfer function to improve the defect classification performance. The defect classification of the modified signal was evaluated in the acceleration signal in the frequency domain using Fisher's discriminant ratio (FDR). The defect classification method was validated by experimental data. By using the method presented, the classification of valve defects can be performed rapidly and efficiently during mass production.

• Korean Journal of Construction Engineering and Management
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• v.19 no.4
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• pp.34-42
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• 2018

Apartment is a typical type of housing preferred by the majority of people. However, and defect disputes occur because various defects such as cracks, subsidence, breakage, water leakage, dew condensation and dropout are confirmed with numerous structures and finishing materials. From this point of view, this paper analyzes defect frequency and costs of each warranty period by work types, and estimates defect risks by using defect dispute cases. It examined about 5,337 defect items for 32 apartment over ten years old. In this paper, there are 10 types of work types and the warranty liability period is divided into 6 categories. Based on these categories, defect frequency and costs are investigated, and finally defect risk of the warranty liability period by work types confirmed. As a result of this analysis, it was found that defect risk in RC and finishing work is very high. Especially the RC work revealed that there is a high risk of trying from the third year onwards and it was found that the defect risk up to the second year is high in the finishing work. Due to aging of RC structure, the defect risk gradually increases, and finishing work initially cause defect disputes because of the housing environment.

• Proceedings of the KIEE Conference
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• 1999.07f
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• pp.2572-2574
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• 1999

본논문은 제작된 다이오드 switching시 나타난 전류 증가현상을 관측하고 그 원인을 분석했다. 증가현상을 보이는 구조는 다이오드에 전자를 조사한 소자로 proton을 조사한 구조에 비해서 접합부근에 high defect density 영역이 형성된다. Reverse recovery시에 이영역에 높은 역방향 전계가 형성, 조사에 순간적으로 전류가 증가하게 한다.

• Journal of the Korea Institute of Building Construction
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• v.21 no.4
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• pp.257-268
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• 2021

This study analyzed the major issues of 24 defect litigation precedents before and after 2013, based on 2013, when defect litigation in relation to the rapidly increasing defect disputes in apartment houses. The amount of defect removal per household is 2,572 thousand won per household, which is about 5% less than before 2013 from 2013, but the judgment amount per household has rather increased by about 19%, showing 1,916 thousand won per household after 2013. By type of construction, defects on cracks accounted for the largest proportion before and after 2013. Before 2013, equipment, tiles, and windows appeared in the order, and after 2013, landscaping, tiles, insulation and window work were in the order. In order to prevent such defect disputes, efforts to prevent defect disputes will be needed in the design stage, construction stage, and maintenance stage.

• Korean Journal of Construction Engineering and Management
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• v.20 no.4
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• pp.13-21
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• 2019

The purpose of this study is to suggest an Improvement Model of defect information management system. The improvement model adapts methods for the residents to input defect information correctly and share to defect information with construction company. The adapted research method is review for existing defect information management system and suggested for data flow diagram of improvement model. The results of this study are as follows: The basic design of the information input window of the defect information management system for connecting with big data was made. And 5 point scale was applied to evaluate the convenience, simplicity, accuracy, necessity, and usability of the improvement model. It is evaluated that the economic effect caused by using the improvement model is saved by about 151 million KRW compared to the existing method. The Improvement model is used utilize big data in correct defect management and decision making.

• Journal of Magnetics
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• v.16 no.4
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• pp.332-336
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• 2011

We studied the effect on the electronic and magnetic properties of the N defect in clean and Cu-doped wurtzite III-nitrides by using the first-principles calculations. When it is doped two Cu atoms in the nearest neighboring sites, the system of AlN, GaN, or InN with the N vacancy is energetically more favorable than that without the N vacancy site. When the Cu concentration increases, the total magnetic moment of a supercell becomes small. The ferromagnetism of Cu atom is very low due to the weak 3d-3d coupling. It is noticeable that the spin-exchange interaction between the Cu-3d and N defect states is important.

• Nuclear Engineering and Technology
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• v.54 no.8
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• pp.2783-2791
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• 2022

Molecular dynamics simulations were performed to predict the behavior of graphite atoms under neutron irradiation using large-scale atomic/molecular massively parallel simulator (LAMMPS) package with adaptive intermolecular reactive empirical bond order (AIREBOM) potential. Defect structures of graphite were compared with results from previous studies by means of density functional theory (DFT) calculations. The quantitative relation between primary knock-on atom (PKA) energy and irradiation damage on graphite was calculated. and the effect of PKA direction on the amount of defects is estimated by counting displaced atoms. Defects are classified into four groups: structural defects, energy defects, vacancies, and near-defect structures, where a structural defect is further subdivided into six types by decision tree method which is one of the supervised machine learning techniques.

• Proceedings of the Korean Institute Of Construction Engineering and Management
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• autumn
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• pp.283-286
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• 2002

Defect problems happening in the course of stressing quantity expansion of residence supply due to lark in maintenance are intensifying insincerity of construction business resulting from the psychological and economic damage, and there are many quarrel between residence suppliers and consumers. Because an apartment house's qualify is decided by various elements from design, to lotting-out, construction, and after-management, it is limited to express house capacity and standard to appraise defect objectively and quantifiably. The bound of defect and the period of guarantee expressed cleary in regulation of apartment house lack in quantifiable concept, and guarantee of defect is composed of a general concept. Therefore the big difference in opinion about defect and the bound of repair makes repair process slow and only to increase social costs. This research will give residence suppliers and consumers a resonable way to solve repair process during tile obliged period of guarantee since moving into from a process which are design, planing, construction, and after management. Furthermore it will present each business and role to conclude defect repair easily, so I planed to promote maintenance after conclusion of defect repair.