• Proceedings of the Korean Magnestics Society Conference
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• 2004.06a
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• pp.134-135
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• 2004

• Proceedings of the Korean Society For Composite Materials Conference
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• 2005.04a
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• pp.42-45
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• 2005

Interfacial evaluation of various combinations of both Flax and Hemp fibers/polypropylene were performed by using micromechanical test and nondestructive acoustic emission (AE). It can be because interfacial adhesion between the natural fiber surface and matrix plays an important role in controlling the overall mechanical properties of polymer composite materials by transferring the stress from the matrix to the fiber. It is necessary to characterize the interphase and the level of adhesion to understand the performance of the composites properly. Microfailure mechanism of single Flax fiber bundles were investigated using the combination of single fiber tensile test and nondestructive acoustic emission. Microfailure modes of the different natural fiber/polypropylene systems were observed using optical microscope and determined indirectly by AE and their FFT analysis.

• KIEAE Journal
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• v.16 no.6
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• pp.151-157
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• 2016

Purpose: The purpose of this study is to develop and apply an environmental impact assessment program for apartment building elements, based on the building materials of the LCI DB, which can link the LCA results of building materials and buildings. Method: For this purpose, a framework for building elements was established, and several building material combinations were developed. In addition, the LCA method for quantifying environmental load emissions from the building materials of each site was applied to establish an environmental impact database of the building materials of the LCI DB. Result: An environmental impact assessment program, based on a Microsoft Excel worksheet, was developed for apartment building elements. This program can link the environmental impact assessment of building materials and building units. To validate the program evaluation results that were obtained in this study, a comparative analysis was carried out using the results of existing evaluation methods. The error rate was estimated to be 5% for environmental impact assessment using existing evaluation methods.

• Journal of the Korean Society for Nondestructive Testing
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• v.22 no.1
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• pp.32-37
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• 2002

The presence of hydrogen in industrial plants is a source of damage. Hydrogen attack is one such form of degradation and often causing large tube ruptures that necessitate an immediate shutdown. Hydrogen attack may reduce the fracture toughness as well as the strength of steels. This reduction is caused partially by the presence of cavities and microcracks at the grain boundaries. In the past several techniques have been used with limited results. This paper describes the application of an ultrasonic velocity and attenuation in hydrogen damage. Ultrasonic tests showed a decrease in wave velocity and an increase in attenuation. Such results demonstrate the potential for ultrasonic nondestructive testing to quantify damage. Based on this study, reliable recommendation is suggested to detect hydrogen attack.

• Applied Microscopy
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• v.32 no.1
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• pp.9-15
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• 2002

Microstructural investigations of $(1-x)NdAlO_3-xCaTiO_3$ (NACT) complex perovskite compounds were carried out using X-ray diffractometry, neutron diffraction and transmission electron microscopy. When $0.3{\leq}x{\leq}0.9$, NACT had not only the 1 : 1 chemical ordering of cations but also the antiphase and inphase tilting of oxygen octahedron and the antiparallel shift of cations. Both the antiphase boundaries and the ferroelastic domains were present in the microstructure. The long and straight ferroelastic domains became degenerate as x decreases. When x was smaller than 0.3, the chemical ordering was absent and the antiphase tilting of oxygen octahedron was observed. The defects like tangled dislocations and the second phase were also found in the microstructure.

• Proceedings of the KIEE Conference
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• 2006.07c
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• pp.1343-1344
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• 2006

There have been numerous accelerated aging laboratory tests for evaluating suitability of polymeric materials and devices. Aging test for materials and its full scale device has been conducted. Service experience plays a key role in the utility section of composite insulators. A meaningful and reliable accelerated aging test is needed for evaluating composite insulator. During the service these insulators are subjected to aging stress such as humidity, pollution, and electrical field, and erosion and tracking of the weathershed occurs. This paper presents the criteria of reliability evaluation and evaluation facilities for 22.9 kV suspension composite insulator. We adopt the criteria of reliability evaluation consist of two test methods. One is CEA tracking wheel test for examining the tracking and erosion performance of composite insulator. The other is multi-stress aging test for examining effects of environmental factors such as UV, temperature, humidity, etc on composite insulator.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2021.11a
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• pp.210-211
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• 2021

This study introduces and demonstrates the application of an experimental regime for anti-seismic performance evaluation of waterproofing materials to used for concrete pile walls. Concrete pile walls are subject to high degree of seismic load, and the occurring stress can affect the waterproofing integrity of the structure, but there is currently no existing methodology or standard for evaluating this property of waterproofing materials. To propose and conduct this evaluation, a new testing apparatus was designed and manufactured intended to be able to test an installed waterproofing material's seismic resistance performance.

• Proceedings of the Materials Research Society of Korea Conference
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• 2000.11a
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• pp.89-89
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• 2000

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.4 no.4
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• pp.50-60
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• 1995

Recently advantages joining dissimiliar materials and light weight material techniques have led to increasing use of structural adhesives in the various industries. Stress singulartiy occurs at the interface edges of adhesively bonded dissimilar materials. So it is required to analyze its stress singularity at the interface edges of adhesively bonded joints indissimilar materials. In this paper, the analysis method of stress singularity is studied in detail. Also, effects of the stress singularity at the interface edge of adhesively bonded scarf joints in combinations of dissimilar materials are investigated by using 2-dimensional elastic program of boundary element method. As the results, the strength evaluation method of adhesively bonded dissimilar materials using the stress singularity factor, $\Gamma$,is very useful. The fracture criterion, method of strength evaluation and prediction of fracture strength by the stress singularity factor on the adhesively bonded dissimilar materials are proposed.

• Corrosion Science and Technology
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• v.6 no.4
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• pp.211-218
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• 2007

In this paper, evaluation and development of corrosion resistant materials for smokestacks is summarized mainly on the basis of the author's experimental results. Operating environments of smokestacks and the problems of conventional lining materials for smokestacks are described briefly. The emphasis is focused upon the evaluation and development of recently developed corrosion resistant steels such as YUS260 for heavy oil fired smokestacks, WELACC5 for LNG fired smokestacks and NSL310MoCu Clad steel for coal fired smokestacks. Corrosion resistance of these steels under laboratory corrosion testing environments and actual environments are evaluated. Finally future problems of corrosion resistant materials for smokestacks are touched on briefly.