• Title/Summary/Keyword: Artificial weathering

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Characterization of Freezing-Thawing on the Artificial Weathering of $TiO_2$ Loaded Granite and Their Physical Property ($TiO_2$가 담지된 화강암의 인공풍화에 미치는 수분의 동결-융해의 평가와 물리적 성질)

  • Shon, Byung-Hyun;Jung, Jong-Hyeon;Kim, Hyun-Gyu;Choung, Young-Hean;Cho, Ki-Chul;Oh, Kwang-Joon
    • Journal of Korean Society of Environmental Engineers
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    • v.28 no.2
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    • pp.183-190
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    • 2006
  • An experimental study was conducted to evaluate the effect of freezing-thawing and air pollutants on the weathering of $TiO_2$ loaded granite. And the granite was coated with $TiO_2$ catalyst and tested. After freezing-thawing and air pollutants experiments the mineral compositions of the granite surface were lower then that of the fresh granite. Density of the weathered granite was steadily decreased from $2.60g/cm^3\;to\;2.55{\sim}2.56g/cm^3$, but absorption ratio and porosity were slightly increased. From these results, it was expected that granite could be weathered by freezing-thawing md air pollutants. In the case of $TiO_2$ was coated to the granite, the compressive strength and absorption ratio were slightly enhanced compared to the $TiO_2$ non-coated granite. Therefore, the $TiO_2$ coating method tested in this study considered to be a viable method to assist in the conservation of granite from environmental contaminants.

Chemical and Morphological Change and Discoloration of Cedar Wood Stored Indoor (실내 보관 삼나무 목재의 재색 및 화학적·현미경적 변화 특성)

  • Lee, Kwang Ho;Cha, Mi Young;Chung, Woo Yang;Bae, Hyeun-Jong;Kim, Yoon Soo
    • Journal of the Korean Wood Science and Technology
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    • v.37 no.6
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    • pp.566-577
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    • 2009
  • The modification of wood color occurs rapidly during the service period at indoor. It is crucial to investigate the characteristics of color change, chemical and microscopical modification of wood at indoor. Wood products made of Japanese cedar at different years were used for this work. The tests were performed in order to evaluate the degree of color change of wood surface, breakpoint of brightness from surface to inside of wood, chemical analysis with FT-IR, and microscopical characteristics using the LM and TEM. Surface color of cedar wood stored indoor were rapidly changed at early stage, particularly ${\Delta}a$ (yellow), and ${\Delta}b$ (red) values were steeply decreased for one year old indoor wood, ${\Delta}L$ (white) value was dropped until 5 years old indoor wood compared with control sample. Decrease of peaks related to polysaccharide and lignin was noticed, especially, lignin was severely degraded. Although degradation of cell wall limited only to surface layers of indoor wood, degradation pattern of indoor wood showed similar degradation pattern to natural weathering of wood during outdoor weathering or wood behavior under artificial UV irradiation.

Modeling Study on Deterioration of Stone Monuments Constructed with Silicate Rock by Acid Rain (규산염질 암석으로 구성된 석조문화재의 산성비에 의한 손상 임상연구)

  • Do, Jin-Young;Cho, Hyen-Goo
    • Journal of the Mineralogical Society of Korea
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    • v.23 no.1
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    • pp.63-71
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    • 2010
  • The artificial rains having different pH and weathering simulation test were performed for Gyeongju Namsan granite and dacitic tuff to predict the role of acid rain in the deterioration of stone monuments located in Gyeongju area. The pH 4.0 rain reacted with the fresh granite showed near neutral pH at the early stage due to the hydrolysis of minerals in the rock surface. But the pH changed back to the initial pH in the later stage. On the other hand, the pH 5.6 rain showed the neutral pH for a longer time than the experiment with pH 4.0 rain, reflecting slower reaction of minerals due to the weaker acidity. When the pH 5.6 rain reacted with the weathered granite, the water showed neutral pH longer than the case of the fresh granite. The similar tendencies were observed in the experiment of dacitic tuff, except that the pH 4.0 rain reacted with dacitic tuff took a longer time to go back to the initial pH as compared with the case of granite. These results may due to the differences in mineral composition and texture of two rocks. Dacitic tuff contains more fine-grained or glassy groundmass than granite and is more reactive with weaker acid rain. It was predicted that the weight loss and strength decrease rate of dacitic tuff would be approximatetly twice relative to those of granite in the same experimental environment.

Mineralogical and Physico-chemical Properties of Sludge Produced During Artificial Sand Processing (국내 화강암류를 이용한 일부 인공쇄석사 제조과정에서 발생되는 슬러지의 광물.물리화학적 특성)

  • Yoo, Jang-Han;Kim, Yong-Ug
    • Journal of the Mineralogical Society of Korea
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    • v.20 no.4
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    • pp.303-311
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    • 2007
  • The consumption of artificially crushed sands exceeds more than 30 percent of the domestic sand supply in South Korea, and its rate is still increasing. For the manufacture of crushed sand granites and granitic gneisses are preferred, fine fractions (i.e. sludge, particles finer than 63 microns) are removed by use of flocculation agents, and its amount occupy about 15 wt%. The sludges consist of quartz, feldspars, micas, chlorite/vermiculite, kaolinites, smectites and occasionally calcite. Among the clay minerals micas are usually predominant, and $14{\AA}$ minerals, kaolinites and smectites are rather scarce. Jurassic granites usually contain more kaolinites and smectites than those of Cretaceous to Tertiary granites, probably due to longer geologic ages. On the other hand, sludge from Precambrian gneiss does not contain kaolinites and smectites. Chemical analyses for the granites and their sludges show rather clear differences in most of major chemical components. Except for $SiO_2,\;Na_2O\;and\;K_2O$, all other components represent rather clear increase. Decrease of $SiO_2$ content is attributed to the relative decrease of quartz in the sludges. And the $Na_2O decrease is caused by a relatively stronger weathering property of albite compared to Ca plagioclase. The $K_2O$ content shows rather small differences throughout the whole samples. The increases of $Al_2O_3$ and other major components resulted from weathering processes and most of colored components are also concentrated in the sludges. Particle size analyses reveal that the sludges are categorized as sandy loams in a sand-silt-clay triangular diagram. The sludge is now classified as industrial waste because of its impermeability, and this result was also confirmed by rather higher hydraulic conductivities. For the environmental problems, and accomplishing effective sand manufacture, more fresh rocks with little weathering products must be chosen.

Factors affecting particle breakage of calcareous soil retrieved from South China Sea

  • Wang, Xinzhi;Shan, Huagang;Wu, Yang;Meng, Qingshan;Zhu, Changqi
    • Geomechanics and Engineering
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    • v.22 no.2
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    • pp.173-185
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    • 2020
  • Calcareous soil is originated from marine biogenic sediments and weathering of carbonate rocks. The formation history for calcareous sediment includes complex physical, biological and chemical processes. It is preferably selected as the major fill materials for hydraulic reclamation and artificial island construction. Calcareous sands possess inter pores and complex shape are liable to be damaged at normal working stress level due to its fragile nature. Thus, the engineering properties of calcareous soil are greatly affected by its high compressibility and crushability. A series of triaxial shear tests were performed on calcareous sands derived from South China Sea under different test conditions. The effects of confining pressure, particle size, grading, compactness, drainage condition, and water content on the total amount of particle breakage for calcareous soil were symmetrically investigated. The test results showed that the crushing extent of calcareous sand with full gradation was smaller than that a single particle group under the same test condition. Large grains are cushioned by surrounding small particles and such micro-structure reduces the probability of breakage for well-graded sands. The increasing tendency of particle crushing for calcareous sand with a rise in confining pressure and compactness is confirmed. It is also evident that a rise in water content enhances the amount of particle breakage for calcareous sand. However, varying tendency of particle breakage with grain size is still controversial and requires further examination.

A Study of Stone Cultural Heritage on Filler Status and Clinical Trials of Conservation Treatment in Cracks - Focusing on the Change in Surface of the Filler by Mixing the Talc - (석조문화재 균열부 보존처리 충전제의 현황과 임상실험 고찰 - 활석을 혼합 한 충전제의 표면변화를 중심으로 -)

  • Lee, Tae Jong;Oh, Hyeon Jung;Kim, Sa Dug;Lee, Jang Jon
    • Journal of Conservation Science
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    • v.30 no.4
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    • pp.383-393
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    • 2014
  • It is used for the epoxy resin, a mixture of various fillers conservation of cracks of the stone cultural heritage. Such as conservation treatment is need to for long-term conservation. However, field research and experiments on the conservation treatment results when included 54 cases of talc filler was confirmed that the damage, such as discoloration and cracks. The field research is talc was used to determine whether the reports and conservator interviews conducted, microscopy, ICP analysis of the samples collected from the field site. Experiments is color difference measurement and Ultrasonic measurement were arried out, and artificial weathering tests to investigate the effect of talc. As a result, lower the property of matter of the samples containing the talc. Therefore, we propose that the selection process is not allowed to use talc as the filler of stone powder filler cracks is conservation treatment.

Preservation and Practical Application of Stromatolites in Gyeong-San (경산 스트로마톨라이트의 보존과 활용방안)

  • Han, Seung Hee
    • Journal of the Korean association of regional geographers
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    • v.23 no.2
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    • pp.366-375
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    • 2017
  • Researching Stromatolites spread all over Gyeong-San, province Gyeongsangbukdo, it raise an objection for preservation of original state caused by natural weathering, artificial destruction, illegal emission and enviromental pollution. Stromatolites in Gyeong-San was formed on lake Meszoic era cretaceous. So it is representative rock of geological feature of sediment formed in water and landscape. It could be used as educational data on mesozoic stratum and earth surface, and resources of observation and experience program. It could apply as educational venue place in terms of Mesozoic era cretaceous motif. And it is managed various programs appling 4H (Healing, Hiking, Hand, History) experience program based on local community. And it is concerned software program introducing augumented reality, furthermore discuss with related field.

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Geomorphological Processes and Changes of Waterfalls formed by Channel Avulsion (하도 변위에 의한 폭포의 형성과 변화)

  • Lee, Gwang-Ryul
    • Journal of the Korean Geographical Society
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    • v.48 no.5
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    • pp.615-628
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    • 2013
  • The waterfall can be formed by difference between the height of up and down part in new channel, is formed by channel avulsion that rapidly changing of river channel course. This study described types and processes of waterfalls by channel avulsion, and analyzed rates and factors of waterfall recession, on object to 7 waterfalls in South Korea. Bulyeong falls at Uljin-gun, Yongchu falls at Yeongdeok-gun, Jikyeon falls at Yanggu-gun and Gwangpum falls at Uljin-gun are formed by natural incised meander cutoff. Samhyeongje falls at Taebaek-si and Guryong falls are formed by river capture processes, and Palbong falls at Chungju-si is formed by artificial channel cutting for farm land secured. The locations of waterfalls gradually moved to upstream over time by head erosion. The recession rates were measured by 3~4m/ka on Bulyeong falls, Yongchu falls, Jikyeon falls and Samhyeongje falls, to estimate of formation age. Recession rates of these 4 waterfalls were analyzed that have clearly positive correlations with drainage area, precipitation, corrosion and weathering capability of bedrock, and initial height of waterfall.

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Spatial Characteristics of Royal Tombs of Chosun Dynasty - With Satellite Imagery and Geological-Geomorphological Analysis - (조선시대 왕릉의 공간적 분포특성 - 위성영상분석과 지질.지형분석의 방법으로 -)

  • Chang, Eun-Mi;Park, Kyeong
    • Spatial Information Research
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    • v.14 no.3 s.38
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    • pp.285-297
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    • 2006
  • We aim to investigate the morphological and environmental characteristics of royal tombs of Chosun Dynasty by using GIS technique and remotely-sensed data. Most of the royal tombs are located on the banded gneiss and granite and over the south- and east. facing slopes and have altitudinal ranges of 150 to 200 meters. Due to the time gaps, exact locational preferences of the royal families can not be understood at this moment and also proximity to the running water is hard to be quantified. Close examination of Gwangneung indicates that the artificial modification and weathering have severe impacts on the slope and stone artefacts. The results from this research can be useful to preserve the valueless cultural heritages.

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Consideration of the Relationship between Independent Variables for the Estimation of Crack Density (균열밀도 산정을 위한 독립 변수 간의 관계 고찰)

  • Yoon, Hyung-Koo
    • Journal of the Korean Geotechnical Society
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    • v.40 no.4
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    • pp.137-144
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    • 2024
  • The purpose of this paper is to analyze the significance of independent variables in estimating crack density using machine learning algorithms. The algorithms used were random forest and SHAP, with the independent variables being compressional wave velocity, shear wave velocity, porosity, and Poisson's ratio. Rock samples were collected from construction sites and processed into cylindrical forms to facilitate the acquisition of each input property. Artificial weathering was conducted twelve times to obtain values for both independent and dependent variables with multiple features. The application of the two algorithms revealed that porosity is a crucial independent variable in estimating crack density, whereas shear wave velocity has a relatively low impact. These results suggested that the four physical properties set as independent variables were sufficient for estimating crack density. Additionally, they presented a methodology for verifying the appropriateness of the independent variables using algorithms such as random forest and SHAP.