• Journal of the Korean Geographical Society
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• v.41 no.4 s.115
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• pp.391-403
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• 2006

The Hanon volcano located in the southern pan of Cheju Island, Korea has a wetland in its crater being used as a farmland. Previous researchers presumed this wetland was a maar lake in the past. Based on the seismic refraction method, the wetland sediment layer was estimated between 5 to 14 m deep, which is mostly in accordance with previous researches. However, this shows only the depths at some sites, not representing the whole spatial distribution. This study is an attempt to reconstruct the volcanic lake in Hanon crater by applying the spatial statistical techniques based on the depth information from the seismic survey and known data. The procedure of reconstruction is as follows: First, the depth information from the seismic survey and known data were collected and it was interpolated by IDW and Ordinary Kriging method. Next, with the interpolation map and the present DEM the paleo DEM was constructed. Finally, using the paleo lake level on core data, the boundary of volcanic lake was extracted from the paleo DEM. The reconstructed lake resembles a half-moon in the north of the central scoria cone. It is estimated that the lake was 5 m deep on average and 13 m deep at the deepest point. Although there are slight differences according to the interpolation techniques, it is calculated that the area of the lake was between 184,000 and $190000m^2,$ and its volume approximately $869,760m^3$. Because of the continuous deposition processes after the crater formation, the reconstructed volcanic lake would not indicate an actual lake at a specific time. Nevertheless, it offers a significant clue regarding the inner morphology and evolution of the crater.

• The Journal of the Petrological Society of Korea
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• v.25 no.3
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• pp.283-298
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• 2016

Sangumburi crater, designated as Natural Monument No. 63, recognized as a maar, but precise geological mapping and geological characteristics in the field indicate that Sangumburi crater is a pit crater. Two stages of volcanic activities created Sangumburi pit crater. Lava flow (aphanitic pyroxene basalt I) and associated pyroclastic deposit (pyroclast I), composed of ash and lapilli, were formed at the stage 1. In the stage 2, lava flow (feldspar olivine basalt) was overlain by lava flow (aphanitic pyroxene basalt II) and associated pyroclastic deposit (pyroclast II), composed of agglomerate. Sangumburi pit crater formed at $0.073{\pm}0.036Ma$, determined by Ar-Ar age dating for the feldspar olivine basalt at the stage 2. It is not clear the preferred migration direction of subsurface magma after Sangumburi pit crater formed.

• Korean journal of applied entomology
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• v.57 no.3
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• pp.191-197
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• 2018

Mites in the family Ascidae are soil dwelling predators of small insects which would have potential to be used as biological control agent. In Korea, 10 genera of 24 species were recorded in the family. During the soil acarine biodiversity study, Asca bicornis Canestrini & Fanzago, 1877 was discovered from moss habitat on Muljangori craer lake 936 m alt in Hallasan mountain in Jeju which was designated as UNESCO Biosphere reserve and World herigate site. We reports this as a new record to Korean Mesostigmata fauna, and provide the morphological description. This species has morphologically characteristic as all dorsal setae nude and needle shaped, lateral caudal projection of Z4 shaped, which are different from the con-general species of A. aphidioides.

• The Journal of the Petrological Society of Korea
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• v.12 no.1
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• pp.1-15
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• 2003

The Paekrogdam summit crater area, Mt. Halla, Jeju Island, Korea, composed of Paekrogdam trachyte, Paekrogdam trachybasalt, and Manseidongsan conglomerate in ascending order. Joint systems show concentric and radial patterns around the summit crate wall. The Paekrogdam crater is a summit crater lake which erupted the tuffs, scorias and lava flows of Paekrogdam trachybasalt after the emplaceent of Paekrogdam trachyte dome. SiO$_2$ contents of mafic and felsic lavas are respectively, 48.0∼53.7 wt.％ and 60.7∼67.4 wt.%, reflecting bimodal volcanism. And lavas with SiO$_2$ between 53.7 wt.% and 60.7 wt.％ are not found. According to TAS diagram and K$_2$O-Na$_2$O diagram, the volcanic rocks belong to the normal alkaline rock series of alkali basalt-trachybasalt-basaltic trachyandesite and trachyte association. Oxide vs. MgO diagrams represent that the mafic lavas fractionated with crystallization of olivine, clinopyroxene, magnetite and ilmenite and felsic trachyte of plagioclase and apatite. The characteristics of trace elements and REEs shows that primary magma for the trachybasalt magma would have been derived from partial melting of garnet peridotite mantle. In the discrimination diagrams, the volcanic rocks are plotted at the region of within plate basalt (WPB).

• The Journal of Engineering Geology
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• v.24 no.4
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• pp.501-510
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• 2014

Volcanic eruptions alone may lead to serious natural disasters, but the associated release of water from a caldera lake may be equally damaging. There is both historical and geological evidence of the past eruptions of Mt. Baekdusan, and the volcano, which has not erupted for over 100 years, has recently shown signs of reawakening. Action is required if we are to limit the social, political, cultural, and economic damage of any future eruption. This study aims to identify the area that would be inundated following a volcanic flood from the Cheon-Ji caldera lake that lies within Mt. Baekdusan. A scenario-based numerical analysis was performed to generate a flood hydrograph, and the parameters required were selected following a consideration of historical records from other volcanoes. The amount of water at the outer rim as a function of time was used as an upper boundary condition for the downstream routing process for a period of 10 days. Data from the USGS were used to generate a DEM with a resolution of 100 m, and remotely sensed satellite data from the moderate-resolution imaging spectroradiometer (MODIS) were used to show land cover and use. The simulation was generated using the software FLO-2D and was superposed on the remotely sensed map. The results show that the inundation area would cover about 80% of the urban area near Erdaobaihezhen assuming a 10 m/hr collapse rate, and 98% of the area would be flooded assuming a 100 m/hr collapse rate.

• Journal of the Korean GEO-environmental Society
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• v.17 no.10
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• pp.55-62
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• 2016

The frequency slope over a year due to climate collapse is connected with huge casualties and property damage, but the situation rarely reduce the damage that gradually increases in size. In order to suppress this, engineers are improved better reinforcement and continued efforts to improve the shear force or withdrawal force. In this study, the GangWhaGu attached to the nail tip that improves the soil nail pullout resistance, and a method to increase the nail integral GangWhaGu maximize the contact area soil - by increasing the friction of the grout seems to increase the effect of slope stability. In order to validate the experiment to determine the effect of reinforcing the soil nail pullout tests of indoor and Behavior GangWhaGu nail and through field tests were conducted and applicability. Experimental results, the case of a pull-out test compared to the GangWhaGu nail through the tensile force of the nail were to increase by approximately 20%.

• Journal of Sericultural and Entomological Science
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• v.27 no.2
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• pp.1-6
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• 1985

To study the non-sprouting causes of mulberry saplings, 8 treatments, borax + lime + compost, borax, lime, Jamsi fertilizer No. 1, heavy nitrogen application, branch harvest, heavy harvest and no treatment were applied on the nursery garden. The tract used as the paddy field before sapling produced was very poor in the soil chemical and physical properties. The results were as follows; 1. The survial rates of saplings were higher than 98% in the treatments of borax, lime, Jamsi fertilizer No. 1, whereas were higher than 98% in the treatments of borax, lime, Jamsi fertilizer No. 1, whereas heavy nitrogen 59% and heavy harvest 71%. 2. The survial rate was showed deeper relationship with the chemical concentration in stem cortex than in root cortex, especially the content of B, Cu and Zn. 3. The nitrogen content in stem cortex was much higher in the heavy nitrogen treatment by 0.89%, where as 0.6∼0.7% in the other treatments. However, treatments of the heavy harvest and the branch harvest were around 5%. 4. In order to decrease the non-sprouting sapling rate, nursery garden should be good in soil chemical and physical properties. Harvest from saplings and heavy nitrogen application should be prevented and lime or Jamsi fertilizer should be applied to saplings.

• Journal of the Korean Society of Food Science and Nutrition
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• v.18 no.2
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• pp.167-174
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• 1989

AS a part of investigation to use anchovy more effectively as food source, this work was undertaken the processing conditions of extracts from rapid fermented anchovy sauce. To prepare rapid fermented products, the chopped anchovy was mixed with 50% water (w/w), and then hydrolyzed by autolysis or addition of koji under different conditions of hydrolysis. The optimal conditions for hydrolysis of chopped anchovy were revealed $50^{\circ}C$, 6 hours, pH 8.0 by autolysis, and ,$50^{\circ}C$, 6 hours, pH 7.0 by addition of 10% koji, respectively. But, pH control was not much beneficial in increasing yield. The effect of soybean protein isolote for improvement of bitter taste was also tested. The reasonable amount of added soybean protein isolate was revealed 5% on the weight basis of the chopped anchovy. The reaction mixture hydrolyzed under optimal conditions were added with 1% onion powder (w/w), 1% garlic powder(w/w) and 1% red pepper powder(w/w) for masking fishy odor, inactivated for 20 min at $100^{\circ}C$, and then centrifuged for 20 min at 4,000 rpm. The supernatant liquor was filtrated and evaporated to 50%(v/v). finally, table salt was added for bateriostatic effect and characteristic taste of rapid fermented products. the reasonable amount of added table salt was reversed 15% on the volume basis of the evaporated liquor. The hydrolysis ratio of product made by addition of water, product made by addition of koji and water, and product made by addition of soybean protein isolate, koji and water hydrolyzed under optimal conditions were 58.4%, 82.1% and 86.2%, respectively.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.14 no.1
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• pp.22-40
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• 2009

Detailed bathymetry and magnetic survey data for NW Rota-1 and Esmeralda Bank obtained by R/V Onnuri of Korea Ocean Research & Development Institute in September 2007 were analyzed to investigate bathymetry and magnetic characteristics of the study area and to estimate the locations of possible hydrothermal vents. The shape of NW Rota-1 is corn type, and the depth of the summit is about 500 meter b.s.l. NW Rota-1 shows irregular topographic expression in the southeastern part. The shape of Esmeralda Bank is caldera type opened in the western part. The summit is very shallow, about 50 meter b.s.l. The western part of Esmeralda Bank is more steeper and topographic irregular than the eastern part, and have the valley made by erosion or collapse. The magnetic anomaly patterns of NW Rota-1 and Esmeralda Bank show low anomalies over the north and high anomalies over the south. The magnetic anomalies are steep over the summits and gently smooth over the deep bottom. The low magnetization zone occurs over the summit of NW Rota-1 and is surrounded by the high zones correlated with its crater. Two low magnetization zones are located in the summit and westside of Esmeralda Bank. The low magnetization zones of the summits of NW Rota-1 and Esmeralda Bank suggest the possible existence of hydrothermal vent.