• Korean Journal of Optics and Photonics
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• v.26 no.5
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• pp.261-264
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• 2015

In this paper we show that the photoresist-protective film of a printed circuit board (PCB) can be delaminated from the underlying photoresist layer by a single pulse of a nanosecond laser at 532 nm. After locally peeling the edge of the PCB with a laser beam of 9 mm size, Scotch tape was attached to the irradiated region to peel off the whole protective film. For a certain range of pulse energies the peeling probability was 100%, without leaving any damage. Since the use of a laser in initial delamination is noncontact and nondamaging, it may be more efficiently utilized in the PCB industry than the conventional knurling method based on mechanical pressing.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.28 no.3
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• pp.91-108
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• 2002

Whitening agents are eagerly demanded especially by oriental women who often suffers from the pigmentary disorders such as melasma and solar lentigines. As these pigmentary disorders are exacerbated by ultraviolet (UV), the whitening agents could exert its effect not only by inhibiting melanin synthesis but also by inhibiting UV activated signals. Eumelanin protects UV-induced DNA damages so that the chemicals which could reduce UV-induced DNA damages might be the ideal lightening agents. The effect of newly synthesized antioxidants, a-tocopheryl ferulate, on protective effect for UV-induced DNA damages as well as inhibiting melanin synthesis are briefly shown. For clinical evaluation, our results of the efficacy of lightening agents on treating pigment macules in combination with chemical peeling are shown. Furthermore, newly developed facial image analyzers to quantitatively evaluate the improvement of pigment macules are introduced.

• Journal of architectural history
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• v.32 no.2
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• pp.37-48
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• 2023

A literature study was conducted on the management of the pavilion of the royal tomb in the late Joseon Dynasty, focusing on "Gakneung Suri Deungnok(Records relating to the repair of royal tombs)". This study analyzed the royal tomb management system, organized the types of damage identified in the building, and examined how the damage status was recorded by type. In the above, the records related to the 1675~1713 repair of three JeongJaGak(Geonwonneung, Sungneung, and Mokneung), which are registered as state-designated cultural properties, are summarized in three aspects: management system, damage status, and expression words. The results of the study are as follows. First, the royal tomb pavilion was regularly inspected by Observator(觀察使) in spring and autumn, and Surunggwan(守陵官) every 5th, and Servant(守僕) regularly inspected every day and night, and also inspected and reported emergency cases of natural disasters or unexpected damage. Second, the damage status of each building was continuously observed and reported for the continuous maintenance of the buildings in the royal tomb. A total of 75 records of damage to the three royal tombs' pavilion were found to have been most frequently inspected, including 19 cases (25.3%), 14 cases (18.7%), 23 cases (30.7%) of the roof, and 19 cases (25.3%) of the roof. Third, the expression of the damage status is confirmed in various ways, such as separation, separation, burst, damage, excitation, moisture, leakage, and exfoliation. Among them, the main damage records were confirmed due to the separation of the base from the peeling, the furniture, cracks, leaks, leaks in the roof, and the collapse of the roof was able to check the damage records.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09b
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• pp.1313-1314
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• 2006

For improvement of wear resistance property of atmospheric thermal plasma sprayed molybdenum (Mo) coating, diamond deposition on the atmospheric plasma sprayed molybdenum coating by the combustion flame chemical vapor deposition (CFCVD) has been operated. In this study, to diminish the thermal damage of the substrate during operation, a thermal insulator was equipped between substrate and water-cooled substrate holder. Consequently, diamond particles could be created on the Mo coating without fracture and peeling off. From these results, it was found that this process had a high potential in order to improve wear resistance of thermal sprayed coating.

• Korean Journal of Heritage: History & Science
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• v.56 no.1
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• pp.100-116
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• 2023

The Sinamsa Temple was built in the late Goryeo Dynasty and a gilt-bronze seated Buddha is enshrined in Geungnakjeon hall in the precinct. Various damages occurred in the gilt layer of the Buddha, such as peeling of the gilt layer and deteriorating gloss. In the study, the conservation conditions of the inside and outside on the statue were accurately investigated, and the making technique was interpreted through the material characteristics and non-destructive diagnosis of the statue. As a result, it is estimated that gold-gilding layer is pure gold, coloration pigment of black is carbon, green is malachite, atacamite and verdigris, red is red lead and cinnabar, respectively. In the deterioration evaluation, peeling, cracking, break out and exfoliation of the gilt layer are confirmed as damages, but the conservation condition is relatively wholesome. However, the gloss of the gilt layer is calculated to be wider in the poorer part than the maintenance part. The ultrasonic velocity of the statue was calculated to be 1,230 to 3,987 (mean 2,608) m/s and showed a relatively wide range. In infrared thermography, peeling was not confirmed, and no special bonding marks were found. In endoscope, some biological damage and corrosion were observed on the surface of the internal metal, and sealed artifacts were identified. Manufacturing technique based on the study, it is considered that the gilt-bronze seated Buddha was cast at once, and the mold was inverted to inject molten metal.

• Journal of the Korea institute for structural maintenance and inspection
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• v.27 no.6
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• pp.30-38
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• 2023

As the number of old buildings subject to safety inspection increases, the burden on designated institutions and management entities that are responsible for safety management is increasing. Accordingly, when selecting buildings subject to safety inspection, appropriate safety inspection standards and appropriate technology are essential. The current safety inspection standards for old buildings give low scores when it is difficult to confirm damage such as cracks in structural members due to finishing materials. This causes the evaluation results to be underestimated regardless of the actual safety status of the structure, resulting in an increase in the number of aging buildings subject to safety inspection. Accordingly, this study proposed a thermal imaging technique, a non-destructive and non-contact inspection, to detect cracks inside finishing materials. A concrete specimen was produced to observe cracks inside the finishing material using a thermal imaging camera, and thermal image data was measured by exciting a heat source on the concrete surface and cracked area. As a result of the measurement, it was confirmed that it was possible to observe cracks inside the finishing material with a width of 0.3mm, 0.5mm, and 0.7mm, but it was difficult to determine the cracks due to uneven temperature distribution due to surface peeling and peeling of the wallpaper. Accordingly, as a result of performing data analysis by deriving the amplitude and phase difference of the thermal image data, clear crack measurement was possible for 0.5mm and 0.7mm cracks. Based on this study, we hope to increase the efficiency of field application and analysis through the development of technology using big data-based deep learning in the diagnosis of internal crack damage in finishing materials.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.6A
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• pp.873-880
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• 2008

When checking the state of deterioration or damage structures, regular visual inspection has very important role. At this point, a visual inspection is performed mainly by sketch or photography with a camera of inspectors. If that happens, it takes a lot of effort and time to inspect appearance damages. The purpose of this study is to develop the automatic recognition system for a more efficient and effective inspection of appearance damages. In the process, the image processing technology and the data management & analysis system for damage recognition are mainly developed and applied. This automatic recognition system enables inspectors or clients to obtain correct data that can recognize a damage, such as, crack, water leakage, efflorescence, delamination (peeling), spalling, etc. In addition, this study takes aim at the effect of secure safety, functional maintenance and extension of design lifetime according to build up continuous and systematic data management system.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2017.05a
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• pp.7-8
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• 2017

Corrosion of reinforced concrete embedded in concrete is a deterioration phenomenon due to intrusion of embodied or Airborne chloride ions. Corrosion of a embedded steel increases the volume of the rebar and causes damage to the structure such as cracking and peeling of the concrete. This causes penetration of various corrosive factors and accelerates the corrosion of reinforcing bars, which has a serious effect on the durability of the structure. Researches on the corrosion phenomenon of these rebars by electrochemical methods have been carried out for a long time, but it is a lack of research in Korea. Therefore, in this study, one of electrochemical experimental methods, Tafel extrapolation method, was used to evaluate the performance of reinforcing bars according to the amount of NaCl and LiNO₂ added to concrete.

• Tribology and Lubricants
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• v.38 no.5
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• pp.222-226
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• 2022

Between diaphragms made of stainless steel (SUS), which is the main component of a hydrogen gas compressor, micro-slip occurs owing to repeated bending, resulting in scratches on the surface. The surface scratch of the compressor part is a problem with airtightness, which reduces the efficiency of the compressor; in severe cases, damage is a possibility. In this study, the changes in friction and wear characteristics due to the surface polishing of SUS and carbon-based solid lubricant films (graphene and CNT) were analyzed. Bare SUS, polished SUS, graphene film, and CNT film specimens were prepared. The surface roughness of the SUS was significantly reduced by surface polishing but increased by carbon-based solid lubricating films. In contrast, the friction coefficient maintained a similar value after surface polishing but was significantly reduced by the carbon-based solid lubricant films. In particular, the graphene film exhibited the lowest initial friction coefficient, while the CNT film exhibited the lowest overall average friction coefficient. Regarding the wear rate, polished SUS exhibited the lowest value, but the surface condition of the wear track showed that the carbon-based solid lubricating films were relatively less damaged. Although the wear rate measured was largely attributed to the solid lubricating film peeling off, the SUS surface under the film was considered protected.

• Journal of the Korean Society of Safety
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• v.29 no.6
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• pp.9-14
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• 2014

Recently many efforts and researches have been done to cope with industrial facilities that require a low energy machines due to the gradual depletion of the natural resources. The fiber-reinforced composite materials in general have good properties and have the proper mechanical properties according to the change of the ply sequences and fiber distribution types. However, in the fiber-reinforced composite material, there are several problems, including fiber breaking, peeling, layer lamination, fiber cracking that can not be seen from the metallic material. Particularly, the fracture and delamination are likely to be affected by the thickness of the stacking laminates when the bi-material laminated structure is subjected to a load of the mixed mode. In this study, we investigated the effect of the thickness ratio of the difference in the CFRP/GFRP bi-material laminate composites by measuring the cracking behavior and the AE characteristics in a mixed mode loading, which may be generated in the actual structure. The results show that the thickness of the CFRP becomes more thick, the mode I energy release rate becomes a larger, and also the influence of mode I is greater than that of mode II. In addition, AE amplitude which shows the level of the damage in the structure was obtained the more damage in the CFRP with the thin thickness.