• Advances in nano research
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• v.12 no.3
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• pp.319-336
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• 2022

Evaluating the temporal and spatial changes in the ecosystem service value (ESV) of the Sanjiangyuan Nature Reserve is important for understanding the impact of human activities on natural ecosystem and guiding ecosystem restoration and environmental pollution control. In this study, remotely sensed land-cover data and the equivalent factor method were used to analyze the spatiotemporal evolution characteristics of the ESV in Sanjiangyuan Nature Reserve from 1992 to 2015, and regression analysis was employed to determine the factors driving changes in the ESV. The results show that grassland was the main type of ecosystem in the study area, and the transformation of grassland into bare areas was the primary change in land cover. Additionally, the ESV in the study area first decreased and then increased, with an annual growth rate of 0.69%. The ESV mainly increased in the north of the Yellow River's source area, and mainly decreased in the northwest of the Yangtze River's source area. Finally, the gross output value of agriculture, urbanization rate and proportion of secondary industry were found to be the main factors driving the ESV in the study area.

• Proceedings of the Korea Water Resources Association Conference
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• 2022.05a
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• pp.143-143
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• 2022

Precipitation plays an essential role in water resources management and disaster prevention. Therefore, the understanding related to spatiotemporal characteristics of rainfall is necessary. Nowadays, highly accurate precipitation is mainly obtained from gauge observation systems. However, the density of gauge stations is a sparse and uneven distribution in mountainous areas. With the proliferation of technology, satellite-based precipitation sources are becoming increasingly common and can provide rainfall information in regions with complex topography. Nevertheless, satellite-based data is that it still remains uncertain. To overcome the above limitation, this study aims to take the strengthens of machine learning to generate a new reanalysis of precipitation data by fusion of multiple satellite precipitation products (SPPs) with gauge observation data. Several machine learning algorithms (i.e., Random Forest, Support Vector Regression, and Artificial Neural Network) have been adopted. To investigate the robustness of the new reanalysis product, observed data were collected to evaluate the accuracy of the products through Kling-Gupta efficiency (KGE), probability of detection (POD), false alarm rate (FAR), and critical success index (CSI). As a result, the new precipitation generated through the machine learning model showed higher accuracy than original satellite rainfall products, and its spatiotemporal variability was better reflected than others. Thus, reanalysis of satellite precipitation product based on machine learning can be useful source input data for hydrological simulations in ungauged river basins.

• PNF and Movement
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• v.20 no.2
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• pp.295-306
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• 2022

Purpose: This study aimed to investigate the effect of robot-assisted gait training on the active ranges of motion, gait abilities, and biomechanical characteristics of gait in patients who underwent lower extremity surgery, and to verify the effectiveness and clinical usefulness of robot-assisted gait training. Methods: This study was conducted on 14 subjects who underwent lower extremity surgery. The subjects participated in robot-assisted gait training for 2 weeks. The active ranges of motion of the lower extremities were evaluated, and gait abilities were assessed using 10-m and 2-min walk tests. An STT Systems Inertial Measurement Unit was used to collect data on biomechanical characteristics during gait. Spatiotemporal parameters were used to measure cadence, step length, and velocity, and kinematic parameters were used to measure hip and knee joint movement during gait. Results: Significant improvements in the active ranges of motion of the hip and knee joints (flexion, extension, abduction, and adduction) and in the 10-m and 2-min walk test results were observed after robot-assisted gait training (p < 0.05). In addition, biomechanical characteristics of gait, spatiotemporal factors (cadence, step length, and velocity), and kinematic factors (gait hip flexion-extension, internal rotation-external rotation angle, and knee joint flexion-extension) were also significantly improved (p < 0.05). Conclusion: The results of this study are of clinical importance as they demonstrate that robot-assisted gait training can be used as an effective intervention method for patients who have undergone lower extremity surgery. Furthermore, the findings of this study are clinically meaningful as they expand the scope of robot-assisted gait training, which is currently mainly applied to patients with central nervous system conditions.

• 한국정보디스플레이학회:학술대회논문집
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• 2008.10a
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• pp.377-380
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• 2008

In this work, we measured the spatiotemporal surface charge distribution by the longitudinal electro-optic amplitude modulation method with BSO single crystal to investigate the decay and diffusion characteristics of surface charges in three types of MgO. The speed of decay and diffusion of two different kinds doped MgO is compared with those of pure MgO. The difference in the characteristics of the decay and diffusion between the electron and ion surface charges is investigated separately. We found that the rate of ion decay is the major factor that makes the difference of the temporal variation of wall voltage among different types doped MgO.

• Applied Science and Convergence Technology
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• v.26 no.4
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• pp.74-78
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• 2017

The discharge characteristics of the radio frequency (RF) surface dielectric barrier discharge have been simulated for the investigation of the ratio of the ion transit time to the RF period. From one-dimensional particle-in-cell (PIC) simulation for a planar dielectric barrier discharge (DBD), it was observed that the high-frequency driving voltage confines the ions in the plasma because of a shorter RF period than the ion transit time. For two-dimensional surface dielectric barrier discharges, a fluid simulation is performed to investigate the characteristics of RF discharges from 1 MHz to 40 MHz. The ratio of the peak density to the average density decreases with the increasing frequency, and the spatiotemporal discharge patterns change abruptly with the change in the ratio of ion transit time to the RF period.

• Progress in Medical Physics
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• v.18 no.1
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• pp.20-26
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• 2007

It is expected that synaptic construction and electrical characteristics In degenerate retina might be different from those In normal retina. Therefore, we analyzed the retinal waveform recorded with multielectrode array in normal and degenerate retina using principal component analysis (PCA) and Independent component analysis (ICA) and compared the results. PCA Is a well established method for retinal waveform while ICA has not tried for retinal waveform analysis. We programmed ICA toolbox for spatiotemporal analysis of retinal waveform. In normal mouse, the MEA spatial map shows a single hot spot perfectly matched with PCA-derived ON or OFF ganglion cell response. However In rd/rd mouse, the MEA spatial map shows numerous hot and cold spots whose underlying interactions and mechanisms need further Investigation for better understanding.

• Phonetics and Speech Sciences
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• v.7 no.1
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• pp.151-163
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• 2015

In this study, we aim to describe kinematic characteristics of Korean /l/-flapping in two speech rates (fast vs. comfortable). Production data was collected from seven native speakers of Seoul Korean (four females and three males) using electromagnetic midsagittal articulometry (EMMA), which provided two dimensional data on the x-y plane. We examined kinematic properties of the vertical/horizontal tongue tip gesture, the vertical/horizontal (rear) tongue body gesture, and the jaw gesture in an /i/-/i/ context. Gestural landmarks of the vertical tongue tip gesture are directly measured. This serves as the actual anchoring time points to which relevant measures of other trajectories referred. The study focuses on velocity profiles, closing/opening spatiotemporal properties, constriction duration, and constriction minima were analyzed. The results are summarized as follows. First, gradiently distributed spatiotemporal values of the vertical tongue tip gesture were on a continuum. This shows more of a reduction in fast speech rate, but no single instance of categorical reduction (deletion). Second, Korean /l/-flapping predominantly exhibited a backward sliding tongue tip movement, in 83% of production, which is apparently distinguished from forward sliding movement in English. Lastly, there was an indication of vocalic reduction in fast rate, truncating spatial displacement of the jaw and the tongue body, although we did not observe positional variations with speech rate. The present study shows that Korean /l/-flapping is characterized by mixed articulatory properties with respect to flapping sounds of other languages such as English and Xiangxiang Chinese. Korean /l/ flapping demonstrates a language-universal property, such as the gradient nature of its flapping sounds that is compatible with other languages. On the other hand, Korean /l/-flapping also shows a language-particular property, particularly distinguished from English, in that a backward gliding movement occurs during the tongue tip closing movement. Although, there was no vocalic reduction in V2 observed in terms of jaw and tongue body height, spatial displacement of these articulators still suggests truncation in fast speech rate.

• Physical Therapy Korea
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• v.9 no.3
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• pp.47-65
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• 2002

This study examined the correlations among the Berg Balance Scale, which is a clinical tool used to evaluate balance ability, spatiotemporal parameters of gait, and falling; determined the parameters most closely related to falling; and identified a discriminatory parameter and its predictability. Thirty-four subjects aged 72 to 92 years participated in this study. Following a questionnaire survey about falling, the Berg Balance Scale and spatiotemporal parameters of gait were measured. The results revealed that the incidence of falls increased with aging and an accompanying reduction in the flexion range of motion of the hip joint. The gait characteristics of elderly people who fell easily included a slower walking speed, shorter stride, and longer stance time than other elderly. When the cutoff score was set at 45, the Berg Balance Scale was able to identify correctly those individuals who truly have experience of falling than when the cutoff score was set at 39. But when the cutoff score was set at 39, the scale's specificity identifying correctly those individuals who truly have not experience of falling was higher than at the cutoff score of 45. Therefore, the Berg Balance Scale is an appropriate screening method in a clinical setting for the early detection of elderly people at risk of falling. In conclusion, elderly people with a Berg Balance Scale score. below 45 are the most likely to fall owing to their decreased balance ability.

• The Journal of the Society of Stroke on Korean Medicine
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• v.14 no.1
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• pp.31-39
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• 2013

■ Objectives The goal of this pilot study is to observe the change of gait pattern according to the clinical status in a patient with ataxic gait by cerebellar infarction. ■ Methods We measured the spatiotemporal gait parameters of a patient with ataxic gait four times, in which, first, the patient was not able to walk independently, second, able to walk independently, third, unable to walk independently by general tremor, and, last, able to walk independently after disappearing of general tremor. ■ Results When a patient with cerebellar ataxic gait was able to walk independently and the cerebellar tremor was disappeared, the change of gait pattern was that step and stride length decreased and total double support and stance phase increased. ■ Conclusion When different clinical characteristics were improved, the change of gait showed same pattern.

• Journal of the Korean Association of Geographic Information Studies
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• v.26 no.4
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• pp.173-187
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• 2023

In an era of population decline, depopulated regions facing challenges in attracting inbound population migration must enhance urban vitality through the attraction of living populations. This study focuses on Busan, a city experiencing population decline, comparing the spatiotemporal distribution characteristics of registered residents and living populations in various administrative districts (Eup-Myeon-Dong) using mobile communication big data. Administrative districts are typified based on population change patterns, and regional characteristics are analyzed using indicators related to urban decline and vitality. Spatiotemporal distribution analysis reveals generally similar density patterns between registered residents and living populations; however, a distinctive feature is observed in the city center areas where the density of registered residents is low, while the density of living populations is high. Divergent trends in spatial patterns of change between registered residents and living populations show clusters of registered population decline in low-density areas and clusters of living population decline in high-density areas. Areas adjacent to declining living populations exhibit large clusters of population changes, indicating a spillover effect from high-density to neighboring areas. Typification results reveal that, even in areas with a decline in registered residents, there is active population influx due to commuting or visiting. These areas sustain an increase in the number of businesses, confirming the presence of industrial and economic growth. However, approximately 47% of administrative districts in Busan are experiencing a decline in both registered residents and living populations, indicating ongoing regional decline. Urgent measures are needed for enhancing urban vitality. The study emphasizes the necessity of utilizing living population data as an urban planning indicator, considering the increasing limit distance of urban activities and growing interregional interaction due to advancements in transportation and communication.