• Journal of the Korean Applied Science and Technology
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• v.27 no.4
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• pp.461-469
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• 2010

Polyurethane adhesive is used in various fields as flexible packaging materials including a food packaging field. Therefore, the purpose of this study is synthesis of polyurethane adhesive which uses aliphatic isocyanate, and compares with aromatic isocyanate. The isocyanates for this test are toluene-2,4-diisocyanate(TDI), hexamethylene diisocyanate(HDI), 4,4-dicyclohexyl ethane diisocyanate($H_{12}MDI$), and isophorone diisocyanate(IPDI). And, the effect of any other diisocyanate are evaluated by several methods as for curing rate test, accelerate weathering test, and peel strength test. The polyurethane adhesive using curing catalyst and HDI has adhesion strength of about 560 g/15 mm between aluminium foil and nylon, about 1,520 g/15 mm between nylon and CPP. Those parameters are similar to polyurethane adhesive with TDI. Also, in case of curing rate, those are similar to TDI type polyurethane adhesive. Moreover, data of ${\Delta}E$ as color variation by QUV tester is equal to 4.12, as 48% against those of TDI type.

• Corrosion Science and Technology
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• v.23 no.1
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• pp.11-19
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• 2024

A Fe-Ni Bainitic steel as a weathering steel application was developed by combining its excellent mechanical properties and corrosion resistance in maritime environments. Nickel concentration (0.4-3 wt%) and inverted austempering multi-step (IAM) process were primary determinants of the microstructure of the Fe-Ni Bainitic steel. The initial austempering steel was performed at 300 ℃ for 600 seconds to obtain a partly bainitic transformation. The steel was heated again for 1800 s at 450 ℃. The microstructure was comprised of ferrite, a blocky martensite/austenite island, and a homogeneous lath-shape bainite structure with widths ranging from 4.67 to 6.89 ㎛. The maximum strength, 1480 MPa, was obtained with 3 wt% nickel. In this study, corrosion behavior was investigated utilizing potentiodynamic and electrochemical impedance spectroscopy (EIS) tests. A higher nickel content in Fe-Ni Bainitic steel refined the grain size, improved the bainite fraction, lowered the corrosion rate to 0.0257 mmpy, and increased the charge transfer of film resistance to 1369 Ω.

• Tunnel and Underground Space
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• v.25 no.5
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• pp.435-449
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• 2015

Physical and microstructural properties of Pungchon and Maggol limestone were investigated quantitatively during 50 cycles of artificial freezing and thawing test. There were decrease in dry weight and P,S-wave velocity, and increase in absorption rate in both rock types. Porosity, pore volume, equivalent diameter, throat thickness and pore orientation were analyzed using X-ray computed tomography images. Porosity increased, and initiation and expansion of pores were investigated as weathering progresses. Physical and microstructural variation in Maggol limestone was larger than that of Pungchon limestone because Maggol limestone has more pores and microcracks at initial state. As this study analyzes physical and microstructural properties of rock specimens comprehensively, it can be applied to further rock weathering study and can be used as fundamental data of construction and resource development in cold regions.

• Journal of the Korean Geographical Society
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• v.47 no.6
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• pp.809-824
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• 2012

Stone cultural heritages quantitatively as well as qualitatively occupy a large proportion in the designated heritages in Korea. The Stone Buddha statue in the Gulbulsa temple site, designated as the No. 121 treasure in 1935, is located in the southwestern slope of Mt. Sogeumgang, Dongcheon-dong, Gyeongju-si, Gyeongbuk Province and Buddhist images are sculptured on four sides of a 3.5m-tall gigantic rock. The damage states result from the weathering degree and indicate high correlation with the water contents. The water contents in the Stone Buddha of Gulbulsa temple site are highest at the east side and then decrease in order of north, south and west sides. These are proportional to the durations of sunshine. Moreover, the Stone Buddha of Gulbulsa temple site with dense joints, repaired areas and vegetated areas by lichens shows high water contents and damage states.

• Economic and Environmental Geology
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• v.52 no.6
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• pp.617-626
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• 2019

In this study, we investigated the petrographic characteristics and physical property of the Rock-carved Seated Buddha at Bugmireugam hermitage of Daeheungsa temple in Haenam. The Buddha Statue was carved on micrographic granite, and the rock was composed of the fine quartz encircled by orthoclase. The results of diagnosis for deterioration evaluation have shown a highly damage rate of black contaminants (8.4%) and crack index (6.6). The ultrasonic velocity have detected SW (slightly weathered) grade of weathering coefficient (mean 0.18). Various weathering factor on the surface of the Buddha Statue was affected by precious shelter, and physical property with ultrasonic was directly influenced by the structural characteristics and fissure of host rock.

• Corrosion Science and Technology
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• v.8 no.6
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• pp.238-242
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• 2009

Corrosion of metallic materials occurs by the reaction with corrosive environment. In general, corrosive environments are classified as atmospheric, marine, soil etc. and regardless of any corrosive environments, reduction of thickness and cracking and degradation are induced by corrosion. Among several corrosive environments, knowing the atmospheric corrosiveness of a region, city, or country is considered of ultimate importance for major industrialists and investors who require knowledge of the corrosive impact of the atmosphere on everyday materials such as carbon steel, weathering steel, zinc, copper, and aluminium. This is why the atmospheric corrosiveness map is needed. This paper dealt with corrosion properties between several waters in the region and carbon steel, weathering steel, galvanized steel, pure copper, and pure aluminium at the representative rural area of Korea - Andong.

• Journal of The Geomorphological Association of Korea
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• v.18 no.1
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• pp.57-71
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• 2011

Granitic regolith profile in Goseong, southern Korea, reveals various types of corestones from unweathered round fresh rocks to decomposed rock cores with unweathered spheroidal rock-layers on outer surface, deep weathering profile with 10m in depth, and red saprolite usually cited as related to high temperature climatic environment. In respect of this optical features such as the depth and the color of the profile, Goseong granitic profile may be regarded as products of paleoclimate with more high temperature and humidity than the present. But it is revealed that halloysite is a predominant clay mineral in upper part as well as lower part by XRD analysis. Halloysite is dominant mineral in hydrothermal alteration milieu. The leaching rate of chemical components is up to 97%, very high compared to common granite profiles with 60~70% in Korean peninsula. So, it is assumed that granitic red regolith in Goseong is a product of hydrothermal alteration, not meteoric weathering.

• Journal of Conservation Science
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• v.26 no.4
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• pp.385-395
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• 2010

This study aimed to identify weathering factors and to assess the conservation environment through microclimatic analysis of Hyeonpung Seokbinggo (ice-storing stone warehouse). The stone blocks inside Seokbinggo suffered crack, displacement, break-out, exfoliation, efflorescence, brown and black discoloration, and biological colonization. Biological colonization represented the maximum deterioration rate(24%) among those weathering forms. The indoor microclimate showed parallel patterns with outdoor one, but the indoor temperature and relative humidity ranged far narrower than outdoor and remained steady. The environmental characteristics resulted from blocking-out of outdoor heat by the closed entrance and surrounding microtopography. This prevented water condensation and freezing effects, so that it reduced physical deterioration of rock, and maximized ice-storing effect for long time. However, contrary to positive effect, extremely high relative humidity over 99% accelerated biological colonization inside the Seokbinggo.

• Journal of Conservation Science
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• v.26 no.3
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• pp.277-294
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• 2010

The Seosanmaaesamjonbulsang (National Treasure No. 84) consists of light gray and coarse to mediumgrained biotite granite with partly developed pegmatite and quartz vein. The host rock is divided into dozens of rock blocks with various shape along irregular discontinuity plane. The evaluation results of discontinuity systems reveal that the host rock were exposed to instable sloping environments. Results of deterioration diagnosis show that the degree of damage has been made worse by physical weathering and surface discoloration laying stress on part that vertical and horizontal joints are massed. Generally, deterioration rate of the triad Buddha surface cover with 42.7%, however, the rate of physical weathering and surface discoloration are subdivided to 9.6% and 33.1%, respectively. Ultrasonic measurements indicate that the triad Buddha was reached highly weathered grade in general. And the rock material was weaken to show low velocity zone of 1,000m/s along irregular joint systems. Indoor and outdoor mean relative humidity of the shelter was recorded more than 70% during every season, and high frequency appears in high relative humidity range over 95%. Such environments seem to have produced dew condensation on the rock surface with rainfall and supply water, promoted physical, chemical and biological weathering along crack and joint, resulting in high permeation of water and percentage of water content. Therefore, it is judged that for scientific conservation of the triad Buddha it needs environment control through persistent preservation environment monitoring including water problem.

• Water for future
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• v.6 no.2
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• pp.19-29
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• 1973

The progressive contamination of water resulted from man's activity and the use of fertilizers is not restricted only to surface water, but also the shallow groundwater is affected. This type of groundwater contamination is mainly restricted to areas composed of permeable, nonconsolidated sediments forming a shallow aquifer. The chloride and the sulfate resulted from man's activity and the use of fertilizers were measured to study the variations of the groundwater contamination. In general, (1) When water level rises, the rate of groundwater contamination becomes less and when water level declines, the rate of contamination is increased. (2) The highly contaminated season is the early-summer and the less contaminated season is the winter or after rainy season. (3) The groundwater in weathering zone without covering layer. (4) The degree of contamination of wells is increased with the increase of well depth and lowing the water table, because of increasing contaminated water from enlargement of the area of influence of the well.