• Korean Journal of Soil Science and Fertilizer
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• v.7 no.3
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• pp.127-135
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• 1974

The samples were taken from the following localities previously classified as "Akiochi" area: Yangpyung, Puchun, and Pyungtaik, all of Kyonggi-do province. Five soil profiles were described in the field, and taken to the laboratory for physical and chemical analysis and mineralogical analysis by X-ray diffraction. The predominant clay minerals consist mainly of illite, vermiculite, chlorites and intergrade with vermiculite, and kaolinite. Illite or mica was found present in all samples and in all horizons. This was identified by the 9.83 to $10{\AA}$ (0.01) and $3.32{\AA}$ (003) basal reflections, Interhorizontal variations in mineral content and crystallinity are illustrated in their respective Xray diffractogram. Comparing the peak intensity, of the $14{\AA}$, $10{\AA}$ and $7{\AA}$ indicated the degree of weathering from the surface to the lower horizons. In general, the weathering of illite on the surface produced less pronounced $10{\AA}$ and $14{\AA}$ peak as compared to the lower horizons. The same may be said with kaolinite. On K-saturation, the $14{\AA}$ peak broadening on the low angle side was observed. This is interpreted to be due to chlorization. Heat treament from $100^{\circ}C$, $200^{\circ}C$, $400^{\circ}C$, $600^{\circ}C$, and $800^{\circ}C$. caused significant changes in the different diffractograms. Heating caused collasped of the $14{\AA}$ to $10{\AA}$ and the appearance of scattered peaks between $10-14{\AA}$. This is interpreted to the presence of vermiculite chlorite intergradient. The complete collapse of the $14{\AA}$ at $800^{\circ}C$ to $10{\AA}$ with increased intensity was attributed to the preservce of vermiculite. The principal difference among the clay minerals in each horizon is the concomitant increase and decrease in intensity with depth of the $14{\AA}$, $10{\AA}$ and $7{\AA}$ diffraction spacings. Apparently the weathering of illite ($10{\AA}$) is resulting in the formation of vermiculite ($14{\AA}$) and the interstratified material being an intermediate stage and the beginning of the formation of vermiculite. Some broadening- in the 17 to $18{\AA}$ was observed in Puchun-1 Pyungtaik-1 and Pyungtaik-2 specially so in the lower horizon in the Ca or Mg-saturated sample. Heated treatment tend to shift this peak to $14{\AA}$ indicating the presence of regular layering of the interstratified complex. The high amount of extractable aluminum and iron coupled with low exchange capacity indicate that iron and aluminum plays an important role in the weathering of these soils and is responsible to the low exchange capacity, high acidity and high phosphate absorptive capacity. The results presented substantiated the weathering sequence of Jackson in that mica ${\rightarrow}$ vermiculite ${\rightarrow}$ chloritezed vermiculite ${\rightarrow}$ kaolinite.

• Journal of Conservation Science
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• v.26 no.4
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• pp.349-360
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• 2010

The Yeongsheon Sinwoldong three-storied stone pagoda (Treasure No. 465) composed mainly of drusy alkali-granite. The major rock-forming minerals are biotite, quartz, amphiboles, orthoclase and plagioclase. Yellowish brown and black discoloration are formed at the eight sculpture Buddha of the stylobate. A broken rock fragments in the roof material were repaired using epoxy resin and cement mortar in the past. As a result of the infrared thermography analysis from the pagoda, cracks and exfoliation were not serious. Also, P-XRF analysis showed that concentration of Fe (mean 5,599ppm) and S (mean 3,270ppm) were so high in yellowish discoloration parts. Black discoloration area was detected highly Mn (mean 2,155ppm) concentration around the eight sculpture Buddha of the stylobate. The main reason for these are inorganic contaminants from disengaged rock ingredient and organic contaminants from withered plant body. Degree of physical weathering is relatively high in the southern and northern side. The eastern and western side had similar with weathering condition. The northern and eastern side were serious discoloration and biological weathering relatively. Therefore, we suggest that the pagoda need to do cleaning of biological contaminant and conservation treatment to weakened materials of rock and long term monitoring.

• Tunnel and Underground Space
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• v.20 no.4
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• pp.241-251
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• 2010

The polar region is in the limelight for an academic worth as well as plenty of natural resources. The study on the polar region was reviewed for better understanding of the polar region and its rock properties. The antarctica has a windy and dry climate along with the lowest temperature on the earth. The thermal distribution according to depth in the area was reported: The freezing-thawing process was repeated in shallow depth, and the temperature falls down below zero under the specific depth. There is a great temperature difference between the atmosphere and rock. A research reported for the degree of weathering of the antarctic slope by using Schmidt hammer and Taffoni test. The rock specimens weathered by repeated freezing-thawing process were tested of the shore hardness and uniaxial compressive strength: The rock strength gradually decreased as the freezing-thawing process was repeated. The comprehensive mechanical properties of the polar region rocks and the relationship between the laboratory weathering test result and the real rock property change in the site remain as future research topics.

• 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.

• Proceedings of the KSR Conference
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• 2001.05a
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• pp.451-458
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• 2001

The purpose of this study was to evaluate shear parameters on cutting slope of weathered granite soils by using small dynamic cone penetration test on the very moment of its cutting. The results were : On the relations among N$\_$c/, Li, and CEC, the condition of Li＞6%, CEC＞14(meq/100g) corresponds to that of N$\_$c/ values of 2∼30, and 3＜CEC＜14(meq/100g) to N$\_$c/=30∼50. Comparing the smallest penetration depth from two small dynamic cone penetration tests done at 5m below from the top of the slope on April 15th, October 31t. there was a l0cm difference. So we could find out the degree of weathering on the slope. And dividing the difference by 190 days (the whole testing time), we could know it's being weathered 0.052mm each day. The more N. value increases, the more shear parameters(internal friction angle ; $\phi$, cohesion : c) increase at a standard pressure($\sigma$＞32㎪). So the condition of N$\_$c/=2∼50 corresponds to that of $\phi$=27∼50, c=12∼49㎪. From the above testing results, the N$\_$c/ values more correspond to $\phi$ values than c values. In conclusion, this study suggests that on small dynamic cone penetration test a penetration boundary line of 5 centimeters is decided at around Li=4%, CEC=3(meq/100g) which is classified as a strong weathering soil. It also shows that as Li increases CEC increases as well, while N$\_$c/ decreases.

• Proceedings of the Korean Geotechical Society Conference
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• 1999.03a
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• pp.159-166
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• 1999

One of the most general methods that can evaluate the rippability is the seismic exploration. However, most field engineers have hardly used the seismic exploration. Instead of using the seismic exploration, they have usually used rock hammer and naked eyes to confirm the degree of rippability for soil, ripping rock and blasting rock. Therefore, to excavate the ground rationally, it is required to establish a quantitative criterion that can be used for distinguishing rippability. In this study, we find out the characteristics of rock strength through laboratory and field tests. The weathering condition of rock exposed to air due to excavation of soil layer and the variation of rock strength caused by weathering were investigated. A relationship between rock strength values that are obtained from uniaxial compression test, slaking durability test, point load test, schmidt hammer test and absorption ratio test is analyzed. The relationship is expressed in a form of equation by which we can evaluate the rock strengths obtained from simple laboratory and field tests. To evaluate rippability in a reasonable manner, a quantitative approach is proposed and a check list of rippability is developed based on the proposed methodology. It is recommended to modify the proposed method for evaluation of rippability in the field.

• Journal of the Korea institute for structural maintenance and inspection
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• v.5 no.1
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• pp.218-227
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• 2001

The purpose of this study was to estimate that the relations of weathering speed and shear strength of granite soil by tracing the weathering depth of granite soil from the very moment of its cutting. The results obtained this follows : This paper is about seismic performance of the EDF(Electricite De France) system, that is among various base isolator. A rational modeling of EDF system has been presented that used Nllink element. We get theoretical solutions of equation of motion of the system and compared with numerical solutions using a finite element program. The unification modeling is made by comparing with behavior using Newmark-${\beta}$ method when input earthquake acceleration data. Thus, a verified modeling will apply bridge structures or multi-degree of-freedom systems.

• Journal of the Mineralogical Society of Korea
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• v.28 no.3
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• pp.255-263
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• 2015

To investigate the effect of the weathering process of biotite on Cs sorption, sorption experiment of Cs with $10^{-3}M$ solution was carried out on the biotite reacted at different reaction times at pH 2 and 4, and 1 M solutions of Na, K, Ca, Mg, Rb, and Cs. Peak changes were observed for some samples by XRD, indicating that new mineral phase formed by biotite weathering. Among several factors, cations in solutions have the most significant influence on the mineralogical changes. The samples reacted with Na showed the most outstanding change with increasing peak width and appearance of $12{\AA}$ peak and $14{\AA}$ peak. This new peaks indicate the formation of hydrobiotite and vermiculite. The new peaks had stronger peak intensity for the sample reacted at pH 4 than that at pH 2, probably due to the fast dissolution of small particles and edges and resultant decrease in the formation of expandable layers. The biotite reacted at Mg solution showed small intensity at $14{\AA}$. Based on XRD results, the degree of biotite weathering was in the order of Na, Mg, and Ca. The samples reacted with K, Rb, Cs solutions did not show noticeable mineralogical changes caused by weathering. The amount of sorbed Cs on weathered biotite showed close relationship with the degree of weathering indicated by XRD. At both pH 2 and 4, the biotite reacted with Na solution showed the highest Cs sorption, and those with Mg and Ca solutions showed the next highest ones. The sorbed amounts of Cs on the bitote reacted with K, Rb, Cs solutions were relatively low. This indicates that at the Cs concentration ($10^{-3}M$) which we used for this experiment and which was much higher than the maximum Cs concentration sorbed on the frayed edge site, expandable layer plays more important role than frayed edge. In the cases of K, Rb, and Cs solutions, Cs sorption was decreased because K is the same cations as the one in the interlayer or the sorption of Rb and Cs on the frayed edge prevents the formation of expandable layers.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.14 no.3
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• pp.583-594
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• 1994

One of the major elements of a natural landslide is the increase of the pore water pressure in a weakened layer. Therefore, the measurement of the pore water pressure in the layer is important. This work is a laboratory model study of the measurement of the pore water pressure with regard to the confined groundwater level, the permeability of the crack zone and the weathering degree of the weakened layer. By the model of the Tertiary period failure type and the Colluvium failure type, the reactions of the pore air pressure and the pore water pressure were measured in the weakened layer according to the permeability of the filter on the condition of the confined groundwater states. On the reaction phase of the pore pressure according to the during time, the Tertiary period failure type proved to be a step type and the Colluvium failure type turned out to be a wave type. The reaction ratios of the pore water pressure in the Tertiary period failure type are higher than the Colluvium failure type, decrease according to increasing of the weathering degree of the weakened layer.

• The Bulletin of The Korean Astronomical Society
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• v.46 no.2
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• pp.57.4-58
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• 2021

Asteroids have undergone various processes such as impacts, space weathering, and thermal evolution. Because they expose their surfaces to space without atmosphere, these evolutional processes have been recorded directly on their surfaces. The remote-sensing observations have been conducted to reveal these evolutional histories of the target asteroids. For example, crater and boulder distributions are unambiguous evidence for past nondestructive impacts with other celestial bodies. Multiband and spectroscopic observations have revealed space-weathering history (as well as compositions). Whereas most physical quantities have been examined intensively using spacecraft and telescopes, only a little has been studied on "the grain size". It is one of the fundamental physical quantities for diagnosing the collisional and thermal history of asteroids. Our group has conducted polarimetric research of asteroids (as well as Moon [1]) to determine the particle size and further investigate the evolutional histories of target asteroids [2],[3]. For example, the existence of regolith on an S-type asteroid, Toutatis, was suggested almost twenty years before space exploration [4]. Moreover, we reported that near-Sun asteroids indicate a signature of submillimeter grains, which could be created by a thermal sintering process by solar radiation [5]. However, it is important to note that in-situ polarimetry has not been reported on the asteroid surface, although the Korean Lunar Exploration Program aims to do polarimetry on the lunar surface [6]. Therefore, it is expected that the polarizer mounted on the Korean Apophis spacecraft can make the first estimate of the grain size and its regional variation over the Apophis surface. In this presentation, we outline research of S-type asteroid surfaces through remote-sensing observations and consider the role of polarimetry. Based on this review, we consider the purpose, potentiality, and strategy of the polarimetry using the onboard device for the Apophis spacecraft. We will report a possible polarization phase curve of Apophis estimated from ordinary chondrites and past observational data of S-type asteroids, taking account of the space weathering effect. Based on this estimation, we will consider the strategy of how to determine the particle size (and space weathering degree) of the Apophis surface. We will also mention the detectability of dust hovering on the surface.