• The Journal of the Korea institute of electronic communication sciences
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• v.13 no.2
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• pp.277-290
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• 2018

Wind data observed by wind profiler provide wind vectors with the altitudes using PCL1300, wind computation program. As a result of application with parameters set in program currently, it is difficult to compute wind vectors in the upper air over 3 km. This id because a very strict criterion for parameters removes large amounts of data. In this study, therefore, we improve the methods of application by resetting parameters to expand data collection area of wind vectors and reduce underestimation. Although the acquisition rate of the wind vector increased from 72.2% to 92.2%, the RMSE of the wind speed maintained 1.5 m/s - 3.1 m/s, which is less than 15% of the error rate at each altitude.

• The Korean Journal of Ecology
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• v.25 no.2
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• pp.83-91
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• 2002

This study was carried out to classify forest vegetation of the Mt. Naeyeon with phytosociological analysis of ZM school and to explain ordination of communities with CCA. The research sites were located between the northern part of Pohang-si area and the southern part of Yeongdeok-gun area. The 70 plots consisted of 253 species were investigated. The forest vegetation was classified into Quercus mongolica community, Q. variabilis community, Pinus densiflora community, Carpinus laxiflora community and Zelkova serrata community. Q. mongolica community was divided into 2 groups such asRhododendron schlippenbachii group and Euonymus oxyphyllus group and Q. variabilis community was divided into 3 groups such as Syneilesis palmata group, Lespedeza × tomentilla group and Tilia mandshurica group, and Z. serrata community was divided into 2 groups such as Carpinus cordata group and Diospyros lotus group. According to the results of CCA ordination, Q. mongolica community showed high positive correlation to altitutde and topography, whereas it showed negative correlation to bare rock. Buck Z. serrata community showed the opposite tendency to Q. mongolica community. Altitude was considered as the most important factor among 5 environmental variables in the correlation with axes.

• Atmosphere
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• v.24 no.4
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• pp.523-532
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• 2014

In this study, thermal tropopause height defined from WMO (World Meteorological Organization) using temperature profile derived from Advance Microwave Sounding Unit-A (AMSU-A; hereafter named AMSU) onboard EOS (Earth Observing System) Aqua satellite is retrieved. The temperature profile of AMSU was validated by comparison with the radiosonde data observed at Osan weather station. The validation in the upper atmosphere from 500 to 100 hPa pressure level showed that correlation coefficients were in the range of 0.85~0.97 and the bias was less than 1 K with Root Mean Square Error (RMSE) of ~3 K. Thermal tropopause height was retrieved by using AMSU temperature profile. The bias and RMSE were found to be -5~ -37 hPa and 45~67 hPa, respectively. Correlation coefficients were in the range of 0.5 to 0.7. We also analyzed the change of tropopause height and temperature in middle troposphere in the extreme heavy rain event (23 October, 2003) associated with tropopause folding. As a result, the distinct descent of tropopause height and temperature decrease of ~8 K at 500 hPa altitude were observed at the hour that maximum precipitation and maximum wind speed occurred. These results were consistent with ERA (ECMWF Reanalysis)-Interim data (potential vorticity, temperature) in time and space.

• Journal of Advanced Navigation Technology
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• v.24 no.1
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• pp.1-8
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• 2020

In this research, we develop an airborne equipment radiating S/C-band signal to a target located at a long distance. RF interface of the equipment comprises band-specific transmitters and an broadband antenna to satisfy EIRP(effective isotropic radiated power) requirements. The equipment is in a shape of a POD like an aircraft fuel tank. The measured weight of the equipment is 119.8 kg, the CG(center of gravity) is 1391.35 mm and the MOI(moment of inertia) are 46.07 ± 0.05(I_yy) kg·㎡, 45.36 ± 0.09(I_zz) kg·㎡. All results are found to meet the requirements for aircraft installation. To verify flight safety, EMI(electromagnetic interference) tests (RE102, CE102), environmental tests (high/low temperature operation, altitude), intra-system EMC(electromagnetic compatibility) and HERP(hazards electromagnetic radiation personnel) tests have been conducted and all the test results met the requirements. It is confirmed that the equipment could be mounted on the aircraft by meeting all electrical and mechanical requirements.

• Journal of the Korean association of regional geographers
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• v.11 no.2
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• pp.187-210
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• 2005

The purpose of this study is to examine the spatial characteristics of the longevity phenomenon and long-live areas in Korea where a rapid aging process is undergoing. Population data from 1966 to 2000 at the county level are analyzed to understand aging process and changes of longevity degree by regions. The relationship between the degree of longevity and a region's natural environments and distance to a metropolis has been analyzed to understand regional factors of longevity. The findings from the study are summarized as follows. Firstly, the rural regions in Honam show the highest degree of longevity in the nation. Secondly, the areas of the high degree of longevity has recently shifted and/or expanded from the islands and seashore areas of southwestern region to inland mountainous areas around Soback Mountain. Southern islands and seashore regions used to show the nation's highest degree of longevity in the 1970s. Thirdly, the analysis of regional environment factors indicated that longevity has more related to a precipitation and an average altitude than temperature. Fourthly, in order to identify the longevity factors in urban areas, social and economic factors should be considered beyond the natural environmental factors.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.25 no.2
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• pp.108-115
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• 2015

Electro-mechanical actuator installed on aircraft consists of a decelerator which magnifies the torque in order to rotate an axis connected with aircraft control surface, a control section which controls the motor assembly through receiving orders from cockpit and a motor assembly which rotates the decelerator. Electro-mechanical actuator controls aircraft altitude, position, landing, takeoff, etc. It is an important part of a aircraft. Aircraft maneuvering causes vibrations to electro-mechanical actuator. Vibrations may result in structural fatigue. For that reason, it is necessary to analyze the system structural safety. In order to analyze the system structural safety. It is needed reasonable finite element model and structural response stress closed to real value. In this paper, analytic model is derived by using the simplified finite element model, and damping ratio which is closely related to response stress is derived by using modal test. So, we developed analytic model in less than 10 % error rate, compared with modal test. Vibration response stress close to real value was estimated from analytic model modified with modal experimental damping ratio. Estimation method for damping ratio with empirical formula was suggested partly. Finally, It was proved that electro-mechanical actuator had reasonable structure margin of safety at environmental random $3{\sigma}$ stress during life cycle.

• Korean Journal of Agricultural and Forest Meteorology
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• v.8 no.3
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• pp.145-151
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• 2006

The purpose of this study was to analyze the relationship between the annual variation in diameter growth of Quercus spp. and climatic factors such as monthly temperature, precipitation and solar radiation in central and northern Korea. Annual diameter growth was measured by using stem cores of 262 Quercus trees, and the correlation between the diameter growth and the climatic factors was analyzed. Mean diameter growth of Quercus spp. in Jungwangsan was larger than that in Woraksan, and mean diameter growth by the species was large in order of Q. serrata>Q. variablis>Q. mongolica>Q. dentata. The diameter growth pattern of Quercus spp. in Woraksan was different from that in Jungwangsan. Positive correlations between diameter growth of Quercus trees and temperature or the solar radiation during July were found in Jungwangsan. Significant correlations between diameter growth and solar radiation during March and precipitation during June were found in Woraksan. It is suggested that climatic factors similarly affect the diameter growth of Quercus spp. in a mountainous terrain, but influences of the climatic factors depend on other environmental conditions such as altitude, topography and soil depth.

• Journal of the Korean association of regional geographers
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• v.21 no.2
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• pp.394-410
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• 2015

This study aims to classify climate zones for extreme climate indices over the Republic of Korea. First, frequencies and magitudes of extreme high temperature, spatial distributions for extreme low temperature, and extreme precipitation are analysed. Frequencies of summer days in inland region show more than coastal region. In frequencies of frost days, the characteristics of altitude and longitude are appeared. Heavy precipitation days show many frequencies in the southern coastal region and Jeju island, but little in Gyeongsangbuk-do region. The classification of climate zone for extreme climate indices by principal component analysis and cluster analysis is conducted for the first half, second half of study period, and climatology period for 1981-2010. Summer days are classified according to latitude. In case of frost days, the eastern and the southern coastal region and Jeju island are classified as same region. Heavy precipitation days are classified according to longitude in south region of Gyeonggi-do and Gangwon-do. This study will help to prepare adaptation and mitigation system for climate change in wide range of fields.

• Korean Journal of Environment and Ecology
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• v.4 no.1
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• pp.33-43
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• 1990

A survey of Popju Temple district. was conducted using 70 sample plots of 500$m^2$ size. The classification by TWINSPAN and DCA ordination were applied to the study area in order to classify them into several groups based on woody plants and environmental variables. By both techniques. the plant com-munity were divided into six groups by the altitude and soil moisture. The successional trends of tree species seem to be from Pinus densiflora, Sorbus alnifolia through Quercus serrata to Carpinus laxiflora and from P. densiflora, Fraxinus sieboldiana through Q. mongolica in the canopy layer, and from Lespedeza cyrtobotrya, Rhus trichocarpa, Zanthoxylum schnifolium through Rhododendron mucronulatum, Corylus sieboldiana, Lindera obtusiloba, Magnclia sieboldii to Euonymus sieboldianus in the understory and shrub layer. The species diversity of the plant community in the burnt plot was decreased by the forest fire but the importance values of Quercus species were increased in above plot.

• Korean Journal of Environment and Ecology
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• v.24 no.6
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• pp.630-637
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• 2010

This study was carried out to classify forest vegetation structure of Sobaeksan National Park from May to October in 2008 using the methodology of the ZM school's phytosociological analysis. The forest vegetation was classified into 1 community groups such as Quercus mongolica community group. Quercus mongolica community group was subdivided into 3 community such as Pinus densiflora community, Acer barbinerve community and Cornus controversa community. Pinus densiflora community was subdivided into Quercus variabilis group and Tilia amurensis group. Acer barbinerve community was also subdivided into Salix hallaisanensis group and Betula ermani group(subdivided into Taxus cuspidata subgroup and Betula ermani typical subgroup). Artificial forest type indicated 2 communities such as Larix leptolepis community and Pinus koraiensis community. Accordingly, the vegetation pattern of the surveyed areas were classified into 1 community groups, 5 communities, 4 groups, and 2 subgroups and the forest vegetation was classified into 8 units in total. The vegetation unit distributions was strongly correlated with sea level and topography in this research area.