• Journal of Conservation Science
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• v.35 no.5
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• pp.494-507
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• 2019

A diagnostic investigation of the conservation state of damaged murals of the Payathonzu temple mainly indicated delamination, exfoliation, and contamination of the coloring layer; cracks and damage to the wall; and separation from gaps. In particular, vulnerabilities resulting from cracks in the wall and damage from gaps demand swift reinforcement measures. Ultrasonic testing uncovered damage caused by gaps between the base layer and plastered wall in several areas of the mural, vulnerable parts in the wall around the cracks, and considerable degradation of the physical properties where cracks and gaps were severe. Moisture measurements identified vast disparities in moisture depending on location even within a single area of the mural, and it was clear that these disparities were the result of environmental conditions such as humidity. Damage to the murals in monument 477 was the most severe, and a diagnostic of the physical properties uncovered severe physical damage to the upper part of the mural as well as to the corridor ceiling, thus presenting the need for conservation treatment utilizing scientific diagnosis as well as objective data.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2013.05a
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• pp.1581-1582
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• 2013

• Earthquakes and Structures
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• v.17 no.2
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• pp.175-189
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• 2019

The aim of the study is to show the results of complex shaking table experimental investigation focused on the response of two models of cylindrical steel tanks under mining tremors and moderate earthquakes, including the aspects of diagnosis of structural damage. Firstly, the impact and the sweep-sine tests have been carried out, so as to determine the dynamic properties of models filled with different levels of liquid. Then, the models have been subjected to seismic and paraseismic excitations. Finally, one fully filled structure has been tested after introducing two different types of damages, so as to verify the method of damage diagnosis. The results of the impact and the sweep-sine tests show that filling the models with liquid leads to substantial reduction in natural frequencies, due to gradually increasing overall mass. Moreover, the results of sweep-sine tests clearly indicate that the increase in the liquid level results in significant increase in the damping structural ratio, which is the effect of damping properties of liquid due to its sloshing. The results of seismic and paraseismic tests indicate that filling the tank with liquid leads initially to considerable reduction in values of acceleration (damping effect of liquid sloshing); however, beyond a certain level of water filling, this regularity is inverted and acceleration values increase (effect of increasing total mass of the structure). Moreover, comparison of the responses under mining tremors and moderate earthquakes indicate that the power amplification factor of the mining tremors may be larger than the seismic power amplification factor. Finally, the results of damage diagnosis of fully filled steel tank model indicate that the forms of the Fourier spectra, together with the frequency and power spectral density values, can be directly related to the specific type of structural damage. They show a decrease in the natural frequencies for the model with unscrewed support bolts (global type of damage), while cutting the welds (local type of damage) has resulted in significant increase in values of the power spectral density for higher vibration modes.

• Tribology and Lubricants
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• v.30 no.6
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• pp.356-363
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• 2014

Marine diesel engines operate in environments in which damage easily occurs from corrosion. Recently, damage to cylinder liners has increased from corrosion wear caused by increased engine power. This damage can cause serious problems in the economy. Thus, many researchers have treated and studied damaged cylinder liners. However, a method is necessary for real-time monitoring of damage to cylinder liners during operation of the engine, before serious damage can occur. This study carries out reciprocating friction and wear tests on a cast iron specimen under various corrosion atmospheres and verifies the variations of friction coefficient and friction surface. Additionally, the friction coefficient and friction status are predicted by using a neural network that learns the vibration and frequency spectrum data from an acceleration sensor. According to our conclusions, amplitude is distributed highly at high frequencies, and values of standard deviation and kurtosis are high when damage to the friction surface is serious. The accuracy rate of the friction coefficient predicted by the neural network is over 80% of the real measured value without NaCl, and application of the neural network is very effective for diagnosing the friction condition and damage to the cylinder liner.

• Journal of the Korean Society for Nondestructive Testing
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• v.32 no.3
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• pp.291-295
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• 2012

In the industrial field, real-time monitoring system like a fault early detection is very important. For this, the infrared thermography technique as a new diagnosis method is proposed. This study is focused on the damage detection and temperature characteristic analysis of ball bearing using the non-destructive infrared thermography method. In this paper, thermal image and temperature data were measured by a Cedip Silver 450 M infrared camera. Based on the results, the temperature characteristics under the conditions of normal, loss lubrication, damage, dynamic loading, and damage under loading were analyzed. It was confirmed that the infrared technique is very useful for the detection of the bearing damage.

• Journal of the Korea institute for structural maintenance and inspection
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• v.3 no.4
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• pp.129-137
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• 1999

Assessment of structural damage is a complex subject imbued with uncertainty and vagueness. This complexity arises from the use of subjective opinion and imprecise numerical data. Recently several active researches have been performed using new methods such as neural network approach or on-line damage detection. In this paper, Damage assessment (diagnosis) of the concrete bridges is studied by a new approach utilizing a neural fuzzy system that combined a neural network and a fuzzy logic. By applying this system to actual in-service bridges, it has been verified that the neural fuzzy method is effective for the bridge diagnosis.

• Journal of Korean Medical classics
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• v.29 no.4
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• pp.17-36
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• 2016

Objectives : This paper seeks to study the provenances of 10 Symptoms of Para-cold damage from Yixuerumen, and discovers the rationality and originality of para-cold damages recognized by Li Chan. Methods : The paper looks through the books referenced by Yixuerumen to investigate the source text for Yixuerumen's Para-cold Damage chapter, and the contents of the referenced books will be compared to that of Yixuerumen. Results : The sources of the 10 symptoms of para-cold damage from Yixuerumen Chapter of Cold Damage can be traced to Leizhenghuorenshu (expectoration, indigestion, rising temperature due to lack of energy, and beriberi), Wang Zhen's Shanghanzhengzhimingtiao Xinzengxuleishanghansizheng(the infection in a boil, blood sattis, caused overexertion, and pox), and Liu Chun's Yujiweiyi's chapter on Common Cold. Here, Li Chan made his own addition of internal damage and damage of overworking. Li Chan seems to have considered para-cold damage not as a type of cold damage but as a "concept relative to the broader range of cold damage." In reflection of this understanding, Li Chan limited the number of categories to ten in accordance with the developmental trace leading from Leizhenghuorenshu to Shanghanzhengzhimingtiao. When we understand para-cold damage as a "concept relative to the narrower range of cold damage," it could be used as a mean as for "Wenbin diagnosis," but Yixuerumen's para-cold damage is only utilized for the "diagnosis of a broader concept of cold damage." Conclusions : Li Chan deserves credits for his academic rationality and originality displayed by the method he used to form para-cold damages where he used real cold damage and para-cold damage as principles, by the division of para-cold damage symptoms into ten provenances, by the creation of the concept of para-cold damage, and by his broad collection of prescription and treatment corresponding to each type.

• Earthquakes and Structures
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• v.18 no.1
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• pp.97-111
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• 2020

Cylindrical steel tanks are important components of industrial facilities. Their safety becomes a crucial issue since any failure may cause catastrophic consequences. The aim of the paper is to show the results of comprehensive FEM numerical investigation focused on the response of cylindrical steel tanks under mining tremors and moderate earthquakes. The effects of different levels of liquid filling, the influence of non-uniform seismic excitation as well as the aspects of diagnosis of structural damage have been investigated. The results of the modal analysis indicate that the level of liquid filling is really essential in the structural analysis leading to considerable changes in the shapes of vibration modes with a substantial reduction in the natural frequencies when the level of liquid increases. The results of seismic and paraseismic analysis indicate that the filling the tank with liquid leads to the substantial increase in the structural response underground motions. It has also been observed that the peak structural response values under mining tremors and moderate earthquakes can be comparable to each other. Moreover, the consideration of spatial effects related to seismic wave propagation leads to a considerable decrease in the structural response under non-uniform seismic excitation. Finally, the analysis of damage diagnosis in steel tanks shows that different types of damage may induce changes in the free vibration modes and values of natural frequencies.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.1165-1168
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• 2017

This paper suggests a fault diagnosis of damage on inner liner of regeneratively-cooled combustion chamber during gas generator cycle rocket engine hot firing test. This method focuses on a phenomenon that fuel flow rate difference between two flow estimate methods changes under an inner liner damage of combustion chamber causing fuel leakage and it is expected that it contributes to detect a damage on the combustion chamber in early stage and prevent further destruction during the hot firing test.

• Journal of Conservation Science
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• v.38 no.4
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• pp.314-326
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• 2022

Investigation of conservation status, optical survey, infrared thermography, and ultrasonic examination were performed on Avalokitesvara Bodhisattva mural and Buddhist Monk Bodhidharma mural to determine the conservation status and physical properties. As a result of investigation of conservation status, the types of damage are largely divided into the wall and finishing layer damage, painting layer degradation, damage due to restoration materials, stains and contamination, and biological damage. As a result of the optical survey, drawing, stains, and repainted site were confirmed. Result of the infrared thermography, the delamination of the finishing layer was confirmed, and some locations and shapes of the wooden lath inside the wall were identified. The result of the 3D scanning, the deviation, and the separation of the wall was confirmed. As a result of ultrasonic examination, it was confirmed that the physical properties of the mural were identified and the ultrasonic speed was relatively low due to physical damage such as delamination and exfoliation of the finishing layer and cracking. Ultrasonic speed values were also high in some wall cracks or delamination, and it was confirmed by the infrared thermography results that the wooden lath inside the wall was located in those parts. It was possible to understand that the wooden lath inside the walls affects the ultrasonic speed during the ultrasonic examination. Therefore, management through periodic inspection of the relevant elements is necessary, and a countermeasure for damage that may occur in the future should be prepared along with intensive monitoring of the major damage identified in this diagnosis result.