• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.32 no.1
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• pp.63-73
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• 2014

Recently, researches on DBRN(DataBase Referenced Navigation) system are being carried out to replace GNSS(Global Navigation Satellite System), as weaknesses of GNSS were found that are caused by the intentional interference and the jamming of the satellite signal. This paper describes the gravity gradient modeling and the construction of EKF(Extended Kalman Filter) based GGRN(Gravity Gradient Referenced Navigation). To analyze the performance of GGRN, fourteen flight trajectories were made for simulations over whole South Korea. During the simulations, we considered the errors in both DB(DataBase) and sensor as well as the flight altitudes. Accurate performances were found, when errors in the DB and the sensor are small and they located at lower altitude. For comparative evaluation, the traditional TRN(Terrain Referenced Navigation) was also developed and performances were analyzed relative to those from the GGRN. In fact, most of GGRN performed better in low altitude, but both of precise gravity gradient DB and gradiometer were required to obtain similar level of precisions at the high altitude. In the future, additional tests and evaluations on the GGRN need to be performed to investigate on more factors such as DB resolution, flight speed, and the update rate.

• Journal of Korea Water Resources Association
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• v.33 no.3
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• pp.279-288
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• 2000

The impact of land slope to the degree of flow divergence was considered employing distributional applications of slope exponents in the now directlOn algoriUnns. Lmear, exponential and ]X)wer law of distributional functIons were employed to address the variation of slope exponents m a terrain analysis. Dongok subwatershed at Wichun test watershed was selected as a study area. Digital Elevation Models of 20m, 30m, 40m and 50m grid size were made to perfonn the analysis. Various calcualtion methodologies of topographic index and the impact of grid sizes were investigated in terms of statistical and spatial aspects. DIstributional applications of slope e.xponents made it possible to represent the flow divergence and convergence about the ten-ain characteristics. The Monte~Carlo method was used to simulate six runoff events to check the impact of topographic factor in the runoff simulation.

• Korean journal of applied entomology
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• v.49 no.3
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• pp.175-185
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• 2010

The effect of altitude and latitude on biodiversity (or species richness) has been a topic of great interest for many biogeographers for a long time. This study was conducted to examine the dynamics of species richness of aquatic insects along the altitudinal gradient in 24 wetlands on Mt. Halla, Jeju and test the Rapoport's rule. The species richness of aquatic insects monotonically decreased with increasing altitude, showing a significant inverse correlation (r = -0.64). However, the pattern of species richness with altitude showed a hump-shaped relationship, with a peak in species richness at intermediate elevations when the effects of area were removed. The altitudinal range of species tended to increase with increasing altitude, as Rapoport's rule predicts. There was a positive correlation between the altitudinal range size and the midpoint of the range size (Median) except for Hemiptera (Odonata: r = 0.75, Hemiptera: r = -0.22, Coleoptera: r = 0.72, Total: r = 0.55). Also, the extent of average altitudinal range of high-altitude species was 904.3m, and it was significantly wider than a 469.5m of low-altitude species. Consequently, the species richness of aquatic insects in wetlands on Mt. Halla along the altitudinal gradient well supported Rapoport's rule.

• Journal of the Korean Society of Propulsion Engineers
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• v.20 no.4
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• pp.87-93
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• 2016

In a Direct Connect(DC) mode altitude engine test, a labyrinth seal is set up between an air intake duct and an engine. The labyrinth seal plays a key role in mechanically isolating them, which contributes to the accurate measurement of thrust and the other component forces. However, when high vertical temperature gradient is generated in the supplied air in the duct, the isolation breaks down. In this paper, a labyrinth seal control device is designed and installed in an effort to eliminate the issue. Test result shows the device successfully gets rid of the contact problem even when high vertical temperature gradient is produced.

• Journal of Korea Water Resources Association
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• v.32 no.4
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• pp.489-499
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• 1999

This research investigated the applicapability of an improved algorithm to calculate the topographic index, ln($\alpha$/tan B), for the topography of Korea employing channel initiation threshold area(CIT) and an exponent for the gradient(H). hanjaechun subwatershed in Cheongdochun and Dongok subwatershed in Wichun test watershed were selected as study areas. The digital elevation models(DEM) of study areas have been made with the resolution from 10m to 100m. Application of CIT to the traditional algorithm provide reasonable computation method in considering channel pixel impact. Introduction of the gradient exponent(H) made it possible to obtain better flow convergence effect in concave topography comparing with the traditional multiple flow direction algorithm. The improved algorithm shows the capability to relax the overestimation problem of rising limb of hydrograph through reducing overestimated high value of topographic index.

• Korean Journal of Ecology and Environment
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• v.46 no.1
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• pp.18-24
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• 2013

The objective of study was to protect seabird breeding site and vegetation restoration of Chilbal and Sokugul island in Shinan county Jeonnam province, April and December 2011. We analyzed the soil properties according to the dominant communities and environmental gradient. As a result, It was highly analyzed to moisture content, organic matter, salinity, total nitrogen in Commelina communis community and low analyzed in Achyranthes japonica community. Carex boottiana community which mainly used as a seabird habitat has a wide range and Achyranthes japonica and Artemisia princeps community was narrowed to soil properties. Soil pH of Carex boottiana community in Sogugul island was the lowest on 3.14 and Peucedanum japonicum community was the highest. Soil moisture content and organic matter was analyzed by the high value in Peucedanum japonicum community. In contrast, Achyranthes japonica was the low value and Carex boottiana community was analyzed the highest on the salinity and total nitrogen. On the soil environmental characteristics according to the environmental gradient, The higher altitude, moisture content, organic matter, salinity and total nitrogen was the lower in Chilbal island. In the case of Sokugul island, the altitude difference did not show the characteristics of soil environmental factors for small area and low altitude. But moisture content is similar to soil property of Chilbal island. Soil property was strongly acid soil because of seabird dropping. This results will be helpful to manage the invasive plants.

• Korean Journal of Plant Resources
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• v.32 no.4
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• pp.325-337
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• 2019

This study was conducted to analyze character of distribution of plants by landforms and altitude in Mt. myeonbong. The chemical properties of soil in this study sites were as follows; pH 4.86, organic 52.53 g/kg, $P_2O_5$ 7.57 mg/kg, potassium $0.18cmol^+/kg$, calcium $2.45cmol^+/kg$ and magnesium $0.49cmol^+/kg$. Generalists in the upper layer were analyzed as follows; Quercus mongolica, Pinus densiflora, Quercus variabilis, and specialists; Carpinus cordata, Tilia amurensis, Morus bombycis etc. In the middle layer, generalists were Betula schmidtii, Quercus mongolica, Sorbus alnifolia and specialists; Lindera erythrocarpa, Quercus serrata, Staphylea bumalda etc. Generalist of shrubs; Lindera obtusiloba, Rhododendron mucronulatum, Sorbus alnifolia, and specialists; Morus bombycis, Pinus densiflora, Deutzia glabrata etc. Generalists of herbaceous layer; Rhus tricocarpa, Lespedeza maximowiczii, Polygonatum odoratum var. pluriflorum and specialists; Liparis kumokiri, Davallia mariesii and Chrysosplenium flagelliferum etc.

• Korean Journal of Microbiology
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• v.24 no.1
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• pp.57-61
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• 1986

In order to remove of cadmium from waste water an identification of a cadmium-ion tolerant yeast B-7 isolated from the sludge of zinc mining district was studied. By the taxonomecal characteristics of strain B-7 it was identified as Hansenula anomala B-7 or similar strain. The cadmium-ion tolerance of the strain B-7 was determined as $2,700{\mu}g/ml$ of cadmium-ion by density gradient agar plate method. The strain B-7 grew well in an aqueous medium containing $1,000{\mu}g/ml$ of cadmium-ion.

• Journal of agriculture & life science
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• v.46 no.4
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• pp.1-8
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• 2012

Acorn production of some oak species from 2008 to 2010 in Mt. Jiri national park(Pia, Bitjeom, Jangdang, Baemsa, Hansin, and Chilsun) was measured and compared among study area, altitude and aspect because acorns are an important wildlife food resources. Acorns were produced the most in Jangdang and Bitjeom area at year of good fruiting, and those of Bitjeom and Hansin area were produced the most at bad fruiting year. In terms of altitudinal characteristics on acorn production, acorn production in 1000 and 900 m was the most at good fruiting year, and 800 and 900 m at bad fruiting year showed the most production of acorn. Throughout the study period, acorn production on southern slopes was larger than that of northern slopes.

• Korean Journal of Agricultural and Forest Meteorology
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• v.20 no.3
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• pp.233-242
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• 2018

This study explored the richness patterns of vascular plant species and evaluated the effects of the climatic and habitat variables on the observed patterns along elevational gradients on the Mt. Baekhwa, South Korea. Plant data were recorded from 70 plots and a total of 187 plant species with 78 woody and 109 herbaceous species were recorded along two study transects, the Banyasa and Bohyunsa transects, on the Mt. Baekhwa. A total of 154 plant species with 66 woody and 88 herbaceous species and 131 plant species with 58 woody and 73 herbaceous species were recorded along the Banyasa and Bohyunsa transects, respectively. We used simple ordinary least squares regression model, multi-model inference and variation partitioning to analyze the relative contribution of climatic and habitat variables on the elevational richness patterns. Species richness pattern for vascular plants along the Banyasa transect monotonically decreased with elevation, whereas plant species richness showed reversed hump-shaped pattern along the Bohyunsa transect. Although the elevational patterns of species richness for vascular plants were different between the both transects, habitat variables are more important predictors than climatic variables for the elevational patterns of plant species richness along our study transects on the Mt. Baekhwa. These results indicate that elevational diversity patterns of vascular plants may be different even between nearby elevational transects in a mountain ecosystem but the diversity patterns may be controlled by same drivers.