• Journal of Astronomy and Space Sciences
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• v.33 no.1
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• pp.21-28
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• 2016

Caves can serve as major outposts for future human exploration of the Moon and Mars. In addition, caves can protect people and electronic equipment from external hazards such as cosmic ray radiation and meteorites impacts and serve as a shelter. Numerous pit craters have been discovered on the Moon and Mars and are potential entrances to caves; the principal topographic features of pit craters are their visible internal floors and pits with vertical walls. We have devised two topographical models for investigating the relationship between the topographical characteristics and the inner void of pit craters. One of our models is a concave floor void model and the other is a convex floor tube model. For each model, optical photographs have been obtained under conditions similar to those in which optical photographs have been acquired for craters on the Moon and Mars. Brightness profiles were analyzed for determining the profile patterns of the void pit craters. The profile patterns were compared to the brightness profiles of Martian pit craters, because no good-quality images of lunar pit craters were available. In future studies, the model profile patterns will be compared to those of lunar pit craters, and the proposed method will likely become useful for finding lunar caves and consequently for planning lunar bases for manned lunar expeditions.

• The Journal of Engineering Geology
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• v.25 no.4
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• pp.473-484
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• 2015

Geophysical exploration using electric resistivity, ground penetrating radar (GPR), and impedance high-frequency (ZHF) surveys was conducted in Gujwa-eup, Jeju City, Jeju Island, an island in the Korea Strait, to confirm the existence of new caves near known caves. The exploration revealed a number of anomaly zones, presumed to be caves; 27 sites at suitable locations and depth ranges were selected for drilling and further surveys. However, contrary to predictions, most of the anomaly zones were clinker layers or paleosols intercalated with lavas. Only five boreholes intersected caves. The clinker layers and paleosols were possibly detected as anomalies owing to their different physical properties from the other rocks. Two of the five cave-finding boreholes penetrated Yongcheon Cave; a new cave was found at the other. The two boreholes that penetrated Yongcheon Cave were drilled in areas where the cave has not been previously reported, and thus helped correct an error in the cave distribution map. The cave newly discovered in this boring exploration is 180 m long, and it is connected to the upstream part of Dangcheomul Cave (110 m). The cave contains well-developed lava helictites, lava levees, and ropy structures; carbonate speleothems such as soda straws, stalagmites, columns, and curtain shawls are also well preserved. Notably, the unique shape of the carbonate speleothems is attributed to their growth in relation to the cavern water that flowed into the cave along plant roots.

• Journal of Astronomy and Space Sciences
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• v.32 no.2
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• pp.113-120
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• 2015

When humans explore the Moon, lunar caves will be an ideal base to provide a shelter from the hazards of radiation, meteorite impact, and extreme diurnal temperature differences. In order to ascertain the existence of caves on the Moon, it is best to visit the Moon in person. The Google Lunar X Prize(GLXP) competition started recently to attempt lunar exploration missions. Ones of those groups competing, plan to land on a pit of Lacus Mortis and determine the existence of a cave inside this pit. In this pit, there is a ramp from the entrance down to the inside of the pit, which enables a rover to approach the inner region of the pit. In this study, under the assumption of the existence of a cave in this pit, a 3D model was developed based on the optical image data. Since this model simulates the actual terrain, the rendering of the model agrees well with the image data. Furthermore, the 3D printing of this model will enable more rigorous investigations and also could be used to publicize lunar exploration missions with ease.

• Journal of Space Technology and Applications
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• v.1 no.2
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• pp.217-240
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• 2021

Upon the human exploration era of the Moon, this paper introduces lunar topography and geologic fundamentals to space scientists. The origin of scientific terminology for the lunar topography was briefly summarized, and the extension of the current Korean terminology is suggested. Specifically, we suggest the most representative lunar topography that are useful to laymen as 1 ocean (Oceanus Procellarum), 10 maria (Mare Imbrium, Mare Serenitatis, Mare Tranuillitatis, Mare Nectaris, Mare Fecundatis, Mare Crisium, Mare Vaporium, Mare Cognitum, Mare Humorum, Mare Nubium), 6 great craters (Tyco, Copernicus, Kepler, Aristachus, Stebinus, Langrenus). We also suggest Korean terms for highland, maria, mountains, crater, rille, rima, graben, dome, lava tube, wrinkle ridge, trench, rupes, and regolith. In addition, we introduce the standard model for the lunar interior and typical rocks. According to the standard model on the basis of historical impact events, the lunar geological eras are classified as Pre-Nectarian, Nectarian, Imbrian, Erathostenesian, and Copernican in chronologic order. Finally, we summarize the latest discovery records on the water on the Moon, and introduce the concept of water extraction from the lunar soil, which is to be developed by the Korea Institute of Geoscience and Mineral Resources (KIGAM).

• Korean Journal of Heritage: History & Science
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• v.46 no.1
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• pp.290-317
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• 2013

The objectives of this study are to investigate the natural heritage and scientific value of various geosites on Udo Island, and to evaluate the sites as natural monuments and as world natural heritage properties. Udo Island includes a variety of geoheritage sites. Various land forms formed during the formation of the Someori Oreum formed by phreatomagmatic eruptions. The essential elements for the formation of Udo Island are the tuff cone, overflowing lava and overlying redeposited tuff sediments. Various coastal land forms are also present. About 6,000 years B.C., when sea-level rose close to its present level due to deglaciation since the Last Glacial Maximum, carbonate sediments have been formed and deposited in shallow marine environment surrounding Udo Island. In particular, the very shallow broad shelf between Udo Island and Jeju Island, less than 20 m in water depth, has provided perfect conditions for the formation of rhodoids. Significant amounts of rhodoids are now forming in this area. Occasional transport of these rhodoids by typhoons has produced unique beach deposits which are entirely composed of rhodoids. Additional features are the Hagosudong Beach with its white carbonate sands, the Geommeole Beach with its black tuffaceous sands and Tolkani Beach with its basalt cobbles and boulders. Near Hagosudong Beach, wind-blown sands in the past produced carbonate sand dunes. On the northern part of the island, special carbonate sediments are present, due to their formation by composite processes such as beach-forming process and transportation by typhoons. The development of several sea caves is another feature of Udo Island, formed by waves and typhoon erosion within tuffaceous sedimentary rocks. In particular, one sea cave found at a depth of 10 m is very special because it indicates past sea-level fluctuations. Shell mounds in Udo Island may well represent the mixed heritage feature on this island. The most valuable geoheritage sites investigated around Udo Isalnd are rhodoid depostis on beaches and in shallow seas, and Someori Oreum composed of volcanoclastic deposits and basalt lava. Beach and shallow marine sediments, composed only of rhodoids, appear to be very rare in the world. Also, the natural heritage value of the Someori Oreum is outstanding, together with other phreatomagmatic tuff cones such as Suwolbong, Songaksan and Yongmeori. Consequently, the rhodoid deposits and the Someori Oreum are worth being nominated for UNESCO World Natural Heritage status. The designation of Someori Oreum as a Natural Monument should be a prerequisite for this procedure.

• The Journal of Engineering Geology
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• v.31 no.3
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• pp.367-380
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• 2021

This study evaluated the stability through a three-dimensional numerical analysis method when a natural cave exists under a road in operation in Jeju Island. In order to confirm the geometric and geotechnical characteristics of the Jeju natural cave passing under the road, existing geotechnical survey reports were collected, and were studied the characteristics. In order to evaluate the effect of vehicle vibration loading on the natural cave in Jeju, three-dimensional numerical analysis was performed considering discontinuities. Through this, the stability of roads and caves with respect to vehicle speed and the depth of cover (distance from the road to the top of the natural cave) was evaluated and countermeasures were suggested. In order to secure the long-term stability of the Jeju natural cave that penetrates the lower part of the road, it was evaluated that systematic management such as long-term measurement management, reinforcement measures, and emergency measures would be necessary depending on the depth of the cover.

• Korean Journal of Environmental Biology
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• v.33 no.4
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• pp.394-402
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• 2015

This study was carried out to investigate the bat (Chiroptera) fauna in Jeju Island. Bat distribution was monitored in lava tubes, sea caves, cave encampments and eco-corridors from July, 2006 to June, 2015. Bat specimens were also confirmed at the museums in Jeju Island. From the present study, we found 8 species of 6 genera belong to 3 families, which was different from the records had previously described in Jeju Island since 1928. Five species (Rhinolophus ferrumequium, Myotis bombinus, M. formosus, M. macrodactylus and Miniopterus schreibersi) were commonly found to live in lava tubes and cave enforcements. But only R. ferrumequium was found in a sea cave and five species including Murina leucogaster and Pipistrellus abramus were found in eco-corridors. We have also found seven species including Tadarida insignis in the specimens stored in local museums. From the results of this study, we actually could not found the remaining seven species (Hypsugo savii, Miniopterus fuscus, Myotis mystacinus, Myotis ikonnikovi, Myotis branditii, Myotis petax and Pipistrellus endoi). Interestingly, Myotis formosus which is known as one of endangered species and Myotis bombinus which is very rare in Korean Peninsula were currently found in Jeju Island. In addition, Tube-nosed bat (Murina leucogaster) that was discovered for the first time through this study. A variety of habitats for Chiroptera were identified, but the information is still not sufficient to understand. These results will be useful to provide a fundamental data in preserving the diversity of bats and in ecological study in Jeju Island.

• Journal of The Geomorphological Association of Korea
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• v.21 no.4
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• pp.149-164
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• 2014

The representative landscapes in Jeju Island called as Ten sceneries of Yeongju originates with Ten sceneries of Tamra which were organized in the late seventeenth century by Jeju governor Lee Iktae. In order to compose ten representative sceneries in Jeju Island, he selected four strongholds such as Jocheon, Byeolbang, Seogwi and Myeongwol and six places of scenic beauty such as Seongsan, Baekrokdam, Yeonggok, Cheonjiyeon, Sanbang and Chwibyeongdam, and made a painting named as Ten sceneries of Tamra. Since the scenes of strongholds also exhibit a lot of geomorphic landscapes, the painting could be considered a collection of representative landforms in Jeju Island. The painting depicts several types of landform such as volcano, crater, river, waterfall, pool, wetland, cavern, tor and rocky coast. The volcanic edifice appears most frequently in the painting, reflecting the particular emotion of Jeju people on Mt. Halla and oreums. However, another volcanic landform, a lava tube, was not highly evaluated due to its negative images. Three famous waterfalls in Jeju Island were included in Ten sceneries of Tamra, and it suggests that they are essentially outstanding landforms, and besides, there are few sites related with fresh water in Jeju Island. The ten sceneries were entirely organized in spite of the limitation of selecting places at that time. The landscape images of Jeju Island, which had been shared as collective representation by Jeju people, were firstly externalized through Lee Iktae's painting, and have long been passed down and established a kind of scenic stereotype.