• Journal of The Geomorphological Association of Korea
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• v.20 no.4
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• pp.37-50
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• 2013

This study analyzes results of published studies of weathering pits in Korea focusing on tafoni and gnamma and it suggests new types of weathering pits and next subjects through the analysis. 34 papers, published between 1978 and February 2012, have been analyzed and the following are details of the analysis. In terms of the study results, weathering pits are commonly developed on coarse-grained rocks such as granite, but also found on various rocks. Multiple reasons including mechanical, chemical and salt weathering create weathering pits and they are closely related to the geological structure. Weathering pits are classified as tafoni and gnamma but the forms have not been verified. In the future, quantitative analysis must be conducted find the factors influencing creation, forms and development of weathering pits.

• Journal of The Geomorphological Association of Korea
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• v.24 no.3
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• pp.119-131
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• 2017

Typical weathering landforms and phenomena including tafoni and gnamma are usually interpreted as man-made alteo (praying water bowl) or dragon-alteo by folklore researchers. Despite some terminological ambiguity, they are certainly natural weathering pits and are introduced in our discipline for fifty years, however, unfortunately most of them are interpreted as petroglyphs used and prepared for ritual ceremony. Several seemingly artificially-made rock holes are also found in many places, but most of them are weathered landforms by salt weathering. Author believes that communication effort to use common language and publish more researches in interdisciplinary journals are very essential to propagate scientific achievements made by geomorphologists to other discipline. Also geomorphologists specialized in weathering processes are encouraged to participate in preservation of stone artifacts and archaeological remains.

• Journal of Industrial Technology
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• v.22 no.B
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• pp.13-20
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• 2002

The purpose of this study is to investigate the effect of acid fog on the rust formation behavior of weathering steel (SMA50) which is used in uncoated bridges. Weathering steel didn't form the passive film under the environment of acid fog(pH5,6), whereas the environment of distilled water formed the protective oxide film. Therefore, the construction of weathering steel under the environment extremely exposed to SOx and NOx which are the main compositions of acid fog is not adequate. Fatigue limits of weathering steel under acid fog environment are remarkably decreased as compared with environment of distilled water. The corrosive constituents in acid fog has piled up the corrosion products on specimen surface and generated the corrosion pits. Because of the high stress concentration arising at this corrosion pit, relatively low fatigue limits were obtained for acid fog specimens.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.32 no.1
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• pp.13-20
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• 2008

The purpose of this study is to investigate the effect of acid fog on the rust formation behavior of weathering steel (SMA50) which is used in un-coated bridges. Weathering steel didn't form the passive film under the environment of acid fog(pH5,6), whereas the environment of distilled water formed the protective oxide film. Therefore, the construction of weathering steel under the environment extremely exposed to SOx and NOx which are the main compositions of acid fog is not adequate. Fatigue limits of weathering steel under acid fog environment are remarkably decreased as compared with environment of distilled water. The corrosive constituents in acid fog has piled up the corrosion products on specimen surface and generated the corrosion pits. Because of the high stress concentration arising at this corrosion pit, relatively low fatigue limits were obtained for acid fog specimens.

• Journal of the Mineralogical Society of Korea
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• v.19 no.2 s.48
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• pp.63-69
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• 2006

When rocks are exposed to the near surface environment, they are broken down due to several factors such as physical and chemical weathering during the geologic time. The feldspar and mica, which are the main rock-forming minerals, are easily broken down relative to other minerals. In order to reproduce some weathered minerals similar to the ones exist in natural weathered granite, there was an experimental interaction between fresh minerals and acidic solution. In low pH condition, biotite initially dissolved and its surface structure broke down, whereas plagioclase dissolved and had a needle-shaped dissolved morphology with some precipitates composed of Al element. The minerals were deeply dissolved in a strong acid condition, showing the prominent dissolved structure. Some etch pits and dissolved textures developed on the natural mineral surfaces are similarly found in our experiment, suggesting the development of mineral dissolution and weathering texture by the influence of the mineral's intrinsic nature.

• Journal of the Korean Geographical Society
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• v.38 no.6
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• pp.922-934
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• 2003

On top of several peaks of Seoraksan National Park. many extensive blockfields are found. After initial report was made in year 2000, further field work and analysis of satellite image have been made. Blockfields on top of mountain peaks exhibit evidence of chemical weathering including gnammas and grooves. Also, several lichen colonies larger than 80 cm in diameter have been found on the surface of many blocks. High resolution IKONOS image has been used to delineate the boundary of blockfields which are hard to access during the field trip. Blockfields of Mt. Seoraksan lack fine material necessary for age dating and clay mineral analysis because they experienced long period of wash and erosion during the Holocene. The ages of blockfields seem to be pre-Holocene on the basis of size of lichen colony and weathering pits.

• Proceedings of the Speleological Society Conference
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• 2005.11a
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• pp.18-32
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• 2005

용신작용에 의한 지형변화에서 지하공간속의 요새화기법을 석회동굴에서 찾아볼 수 있듯이, 여러가지 자연현상 중에서 풍화작용을 같은 원인적 현상에 의한 변형을 통하여 오랜 세월속의 지형지물의 변화에서 나마(gnamma/가마솥바위), 타포니(tafoni/벌집바위) 등의 풍화혈(風化穴/weathering pits)과 같은 기이한 지형물들을 만나볼 수 있다, 특히 우리나라는 대륙에 이어진 반도국가로서 해양성기후권의 해안에서의 해식이나 파식 현상으로 인한 해식애와 파식대 및 해식동굴 등 지형물의 특이한 변화현상이 두드러져 나타나 발견되고 있다. 본 논문은 우리나라 곳곳에 분산되어있는 자연속의 여러 가지 변형지물들을 고찰하기 위하여 먼저 풍화작용과 그 풍화물들에 대한 특이한 지형의 성인과 특징 분석을 통하여 현존 상태의 지형미학적 측면을 비교 관찰하고, 자연의 아름다움과 현경의 중요성을 새롭게 인식하면서 우리의 역할과 가치의 의미를 재조명해보는 현지탐사 활동과 자료조사의 일부이다.

• Journal of the Korean Geographical Society
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• v.41 no.3 s.114
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• pp.331-345
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• 2006

This study deals with geomorphological process of the sand dune landform including the distribution and surface environments, characteristics of sediments, origins and moving processes in lower reach and mouth delta of Duman River, Northeast Korea and China. The methodology of the study includes image analysis of Landsat TM(1992.10) and ETM(2000.9) and Spot(2005.4) for analysis of land cover, 2 times field survey for recognition of landform and acquisition of sediments raw data materials, and grain analysis and exoscopy about raw data materials. The geomorphic elements from satellite image analysis are composed of the delta, sand spit, active and stable dune, sand bar and riparian vegetated zone. Results of the grain analysis indicate the sediments originated from marine coastal zone than riverine one. This means that present sand dune not so much reflect present climatic and geomorphic environments. Result of the exoscopy analysis show that ratio of quartz, which is comparatively resistant to environment, is highest as $65{\sim}83%$ out of sediments. But the surface of the $30{\sim}40%$ of mineral grains was coated by yellow-colored stained materials, due to chemical weathering. Some grains show rough skin, looking as acicular, network structure and etching pits, affected by physical and chemical weathering.

• Journal of The Geomorphological Association of Korea
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• v.15 no.2
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• pp.1-9
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• 2008

This studied area is divided into the mountains and the valleys. The former is nearly consisted of the badland, the latter is consisted of alluvial plains in the valley, fluvial terrace at the side of the river, alluvial fans between mountains and river terrace. There are many tors, mushroom rocks, sugarloaves, weathering pits, castle coppies, columnar rocks, pinnacles, balanced rocks carved on tuff by means of erosion in the Chiricahua Nat'l Monument. Willcox Playa is alkalic crust where was lake in pleistocene epoch at the time wetter than present. Alkalic crust was made of Ca, Na, K etc. There are sand dunes around here where was lake side in the past. We found many kinds of fossils at the 2,000ft thick horizons of valley alluvium. Pediment and alluvium bordered at the base of Mt. Dragoon wavily. Exfoliation and spalling and sheeting resulted in boulders around here. Tucson is alluvial plain filled in thick 7,0000ft valley. Volcano, fault, erosion, alluvium were and are processing in this area.

• Journal of The Geomorphological Association of Korea
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• v.18 no.4
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• pp.35-57
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• 2011

Minor erosional forms in the bedrock river, like potholes, are not just research subject for the professional geomorphologis. In addition, these features attract general public and make them understand the social contribution and importance of geomorphologic research activities. In this paper, the studies on bedrock minor forms in Korea was reviewed. For further researches, some of major erosional processes and minor forms in bedrock rivers were discussed in detail. Cavitation, plucking, hydro-wedging, and abrasion by passing sediment particles are the major processes to create the longitudinal or transverse minor forms like pothole, furrows, flutes, and runnels. Especially the definition of furrows and runnels are explained to prevent the confusion with pothole, weathering pits and grooves. To make a progress in research on bedrock minor forms the quantitative relationship between the variables should be studied. New techniques for scientific estimation of erosion rates and exposure ages of bedrock surfaces should be used in this field.