• Korean Journal of Remote Sensing
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• v.32 no.3
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• pp.331-337
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• 2016

Water vapor is main absorption factor of outgoing longwave radiation. So, it is essential to monitoring the changes in the amount of water vapor and to understanding the causes of such changes. In this study, we monitor temporal variability of Total Precipitable Water (TPW) which observed by satellite. Among climate variables, precipitation play an important part to analyze temporal variability of water vapor because it is produced by water vapor. And El $Ni{\tilde{n}}o$ is one of climate variables which appear regularly in comparison with the others. Through them, we analyze relationship between temporal variability of TPW and climate variable. In this study, we analyzed long-term change of TPW from Moderate-Resolution Imaging Spectroadiometer (MODIS) data and change of precipitation in middle area of Korea peninsula quantitatively. After these analysis, we compared relation of TPW and precipitation with El $Ni{\tilde{n}}o$. The aim of study is to research El $Ni{\tilde{n}}o$ has an impact on TPW and precipitation change in middle area of Korea peninsula. First of all, we calculated TPW and precipitation from time series analysis quantitatively, and anomaly analysis is performed to analyze their correlation. As a result, TPW and precipitation has correlation mostly but the part had inverse correlation was found. This was compared with El $Ni{\tilde{n}}o$ of anomaly results. As a result, TPW and precipitation had inverse correlation after El $Ni{\tilde{n}}o$ occurred. It was found that El $Ni{\tilde{n}}o$ have a decisive effect on change of TPW and precipitation.

• Korean Journal of Applied Biomechanics
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• v.17 no.4
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• pp.1-8
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• 2007

The purpose of this study was to investigate the difference in the stride-to-stride variability between two treadmill conditions; traditional treadmill and special treadmill whose speed can be adjusted automatically by subject's walking speed. Eight male subjects (25.1 years, 172.7 cm, 66.6 kg) were participated in treadmill walking experiment. First, preferred walking speed (PWS) of each subject was determined. Second, each subject performed walking experiment with fixed PWS condition and with free PWS condition for 10 minutes. 3D motion capture system (Motion analysis Corp., USA) with 6 cameras was used to collect motion data with sampling frequency of 120Hz. Temporal and spatial variables for stride-to-stride variability were calculated. Coefficient of variance (CV) which quantifies the amount of variability and Detrended Fluctuation Analysis (DFA) which explains the structure (self-similarity) of the variability were used for analysis. Results showed that the amount of variability during free PWS condition was greater than that of fixed PWS condition. DFA results showed that there was a statistical difference between two treadmill conditions for the variables of step length, stance time, and double support time. From these results, it is possible that traditional treadmill study might give incorrect conclusion about gait variability study. Further study is necessary to clarify these matters by considering the number of subjects, experimental time, and gait variables for the study of stride-to-stride variability.

• Korean Journal of Remote Sensing
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• v.36 no.5_1
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• pp.707-723
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• 2020

In this study, a decision tree type of quality control (QC) method was developed to improve the temporal-spatial representation and accuracy of the visibility data being operated by the Korea Meteorological Administration (KMA). The quality of the developed QC method was evaluated through the application to the 3 years (2016.03-2019.02) of 290 stations visibility data. For qualitative and quantitative verification of the developed QC method, visibility and naked-eye data provided by the KMA and QC method of the Norwegian Meteorological Institute (NMI) were used. Firstly, if the sum of missing and abnormal data exceeds 10% of the total data, the corresponding point was removed. In the 2nd step, a temporal continuity test was performed under the assumption that the visibility changes continuously in time. In this process, the threshold was dynamically set considering the different temporal variability depending on the visibility. In the 3rd step, the spatial continuity test was performed under the assumption of spatial continuity for visibility. Finally, the 10-minute visibility data was calculated using weighted average method, considering that the accuracy of the visibility meter was inversely proportional to the visibility. As results, about 10% of the data were removed in the first step due to the large temporal-spatial variability of visibility. In addition, because the spatial variability was significant, especially around the fog area, the 3rd step was not applied. Through the quantitative verification results, it suggested that the QC method developed in this study can be used as a QC tool for visibility data.

• Animal cells and systems
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• v.3 no.3
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• pp.275-283
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• 1999

Korean R. plancyi occupies a restricted area in western South Korea and shows a relatively low level of genic variability (%P＝15.2, Ho=0.052, He＝0.048). In contrast, R. nigromaculata is broadly distributed in South Korea. The observed low level of variability of R. nigromaculata (%P＝14.3, Ho＝0.042, He＝0.043) is probably due to its recent colonization. Populations of R. nigromaculata exhibited considerable genetic differentiation (F$_{sT}$=0.149) and low level of gene flow (Nm＝1.427) among populations, compared to those of R. Plancyi (F$_{sTF$_{sT}$}$=0.096, Nm＝2.354), which occupies a restricted area. The observed levels of gene flow among populations of R. nigromaculata (Nm＝1.427) over a broad geographic range is relatively higher than other amphibian species. The high level of gene flow is probably the result of the high dispersal abilities of R. nigromaculata. A survey of temporal genic variation of R. nigromaculata showed that there was no significant change on the overall average genetic diversity from 1978 (average He＝0.044) to 1997 (average He＝0.040). Wright's F-statistics also indicated no significant genetic differentiation from 1978 (F$_{sT}$＝0.118) to 1997 (F$_{sT}$＝0.108). This suggests that the environmental change appears to have had little influence on the genetic composition of R. nigromaculata in the study areas during the past 20 years. The low level of temporal variation might be due to the result of high dispersal abilities and wide migration range of this species.

• Journal of Korea Water Resources Association
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• v.34 no.1
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• pp.67-80
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• 2001

This study is to propose temporal pattern of design rainfall which causes maximum peak discharge and to analyze the variation in peak discharge according to design rainfall durations. In this study, the Mononobe, the Yen and Chow triangular, the Huff's 4th quartiles and the Keifer and Chu methods are applied to estimate the proper temporal pattern of design rainfall and three rainfall-runoff models such as SCS, Nakayasu, and Clark methods are used to estimate the runoff hydrograph. And to examine the variability of peak discharge, the hydrologic characteristics from the rainfall-runoff models to which uniform rainfall intensity is applied are used as the standard values. The type of temporal pattern of design rainfall which causes maximum peak discharge in both of the watersheds and the rainfall-runoff models has resulted in Yen and Chow distribution method with the dimensionless vague of 0.75. On the basis of determined temporal pattern, the examination of the variability of peak discharge according to design rainfall durations shows that design rainfall duration varies greatly with the types of probable intensity formula, and the variation of peak discharge is more affected by the types of probable intensity formula and I-D-F currie than rainfall-runoff models.

• The Journal of Engineering Geology
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• v.21 no.4
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• pp.305-312
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• 2011

Because groundwater recharge shows spatial-temporal variability due to climatic conditions, it is necessary to investigate land use and hydrogeological heterogeneity, and estimate the spatial variability in the daily recharge rate based on an integrated surface-groundwater model. The integrated SWAT-MODFLOW model was applied to compute physically based daily groundwater recharge in the Jincheon region. The temporal variations in estimated recharge were calibrated using the observed groundwater head at several National Groundwater Monitoring Stations and at automatic groundwater-monitoring sites constructed during the Basic Groundwater Investigation Project (2009-2010). For the whole Mihocheon watershed, including the Jincheon region, the average groundwater recharge rate is estimated to be 20.8% of the total rainfall amount, which is in good agreement with the analytically estimated recharge rate. The proposed methodology will be a useful tool in the management of groundwater in Korea.

• The Bulletin of The Korean Astronomical Society
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• v.39 no.1
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• pp.45.1-45.1
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• 2014

We present the results of a time series analysis of the long-term radio lightcurves of four blazars: 3C 279, 3C 345, 3C 446, and BL Lacertae. We exploit the data base of the University of Michigan Radio Astronomy Observatory (UMRAO) monitoring program which provides densely sampled lightcurves spanning 32 years in time in three frequency bands located at 4.8, 8, and 14.5,GHz. Our sources show mostly flat or inverted (spectral indices -0.5 < alpha < 0) spectra, in agreement with optically thick emission. All lightcurves show strong variability on all time scales. Analyzing the time lags between the lightcurves from different frequency bands, we find that we can distinguish high-peaking flares and low-peaking flares in accord with the classification of Valtaoja et al. (1992). The periodograms (temporal power spectra) of the observed lightcurves are consistent with random-walk powerlaw noise without any indication of (quasi-)periodic variability. The fact that all four sources studied are in agreement with being random-walk noise emitters at radio wavelengths suggests that such behavior is a general property of blazars.

• Journal of Biomedical Engineering Research
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• v.40 no.3
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• pp.75-80
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• 2019

Listening effort represents the listener's attention, stress, required cognition resource, and mental exertion to understand a speech in various situations. Recently, it has been focused to evaluate an effectiveness of hearing aids and cochlear implant. The physiologic measures, such as heart rate, skin conductance, electroencephalography, and pupil dilation, have been used to objectively measure listening effort. In this study, we investigated the feasibility of temporal and spectral heart rate variabilities to measure listening effort to understand speech in the presence of background noise. The results showed that several heart rate variabilities significantly increased as increasing background noise level. Finally, the heart rate variability can be used as an objective tool to measure listening efforts.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2008.10a
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• pp.274-274
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• 2008

• Journal of Forest and Environmental Science
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• v.33 no.3
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• pp.161-171
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• 2017

Global environmental changes have the capacity to make dramatic alterations to floral and faunal composition, and elucidation of the mechanism is important for predicting its outcomes. Studies on global climate change have traditionally focused on statistical summaries within relatively wide scales of spatial and temporal changes, and less attention has been paid to variability in microclimates across spatial and temporal scales. Microclimate is a suite of climatic conditions measured in local areas near the earth's surface. Environmental variables in microclimatic scale can be critical for the ecology of organisms inhabiting there. Here we examine the effect of spatial and temporal changes in microclimates on those of carabid beetle communities in Hyangnobong, Korea. We found that climatic variables and the patterns of annual changes in carabid beetle communities differed among sites even within the single mountain system. Our results indicate the importance of temporal survey of communities at local scales, which is expected to reveal an additional fraction of variation in communities and underlying processes that has been overlooked in studies of global community patterns and changes.