• Communications for Statistical Applications and Methods
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• v.31 no.5
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• pp.521-533
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• 2024

As the concentration of fine dust has recently increased, numerous related studies are being conducted to address this issue. Aerosol optical depth (AOD) is a vital atmospheric parameter for measuring the optical properties of aerosols in the atmosphere, providing crucial information related to fine dust. In this paper, we apply three dimension reduction methods, nonnegative matrix factorization (NMF), empirical orthogonal functions (EOF) analysis and independent component analysis (ICA), to AOD data to analyze the patterns of fine dust in the East Asia region. Through a comparison of three dimension reduction methods, we observe that some patterns are observed in all three method, while some information are only extracted in a specific method. Additionally, we forecast AOD levels based on three methods, and compare the predictive performance of the three methodologies.

• Korean Journal of Soil Science and Fertilizer
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• v.16 no.3
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• pp.228-234
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• 1983

The effects of subsoiling on improving soil physical properties for increasing yield of rice were studied at different depths and spacings in a clay loam paddy soils. The results are summarized as follows : 1. Working efficiencies of subsoiling at depth 50cm were lower than those at depth 30cm by tractor, while subsoiling ratios at depth 50cm were higher than those at depth 30cm. 2. During cultivation period, water requirement in 50cm depth subsoiling was higher than that in 30cm depth subsoiling. Water requirement in the central part was more rapid about 1.0-2.0mm/day than in the middle between two neighbouring central points. 3. Soil physical properties such as hardness, bulk density and porosity were significantly improved by subsoiling and the subsoiling effects have been continued until the second year. Negative correlations between yield and bulk density or hardness of subsoil were observed. 4. A lograrithmic function was observed between rice yield ($\hat{Y}$) and subsoiling ratio(X) at depth of 20cm. The optimum space for subsoiling in 30 and 50cm depth. was 80 and 120cm, respectively.

• Korean Journal of Optics and Photonics
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• v.20 no.1
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• pp.16-22
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• 2009

We propose a method to convert a two-dimensional movie to a three-dimensional movie using normalized cut and optical flow. In this paper, we segment an image of a two-dimensional movie to objects first, and then estimate the depth of each object. Normalized cut is one of the image segmentation algorithms. For improving speed and accuracy of normalized cut, we used a watershed algorithm and a weight function using optical flow. We estimate the depth of objects which are segmented by improved normalized cut using optical flow. Ordinal depth is estimated by the change of the segmented object label in an occluded region which is the difference of absolute values of optical flow. For compensating ordinal depth, we generate the relational depth which is the absolute value of optical flow as motion parallax. A final depth map is determined by multiplying ordinal depth by relational depth, then dividing by average optical flow. In this research, we propose the two-dimensional/three-dimensional movie conversion method which is applicable to all three-dimensional display devices and all two-dimensional movie formats. We present experimental results using sample two-dimensional movies.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.2B
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• pp.111-120
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• 2009

A local scour around a bridge pier is known as one of important factors of bridge collapse. Two approaches are usually used in estimating a scour depth in practice. One is to use empirical formulas, and the other is to use computational methods. But the use of empirical formulas is limited to predict a scour depth under similar conditions to which the formulas were derived. Computational methods are currently too expensive to be applied to practical engineering problems. This study presented the application of artificial neural networks (ANN) to the prediction of a scour depth around a bridge pier at an equilibrium state. This study also investigated various ANN algorithms for estimating a scour depth, such as Backpropagation Network, Radial Basis Function Network, and Generalized Regression Network. Preliminary study showed that ANN models resulted in very wide range of errors in predicting a scour depth. To solve this problem this study incorporated cluster analysis into ANN. The incorporation of cluster analysis provided better estimations of scour depth up to 42% compared with other approaches.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.10 no.4
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• pp.53-66
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• 1990

Rainfall is a phenomenon that shows a high variability both in space and time, Hy drologists are usually interested in the description of spatial distribution of rainfall over watershed. The theory of Kriging, generalized covariance technique using nonstationary mean in the regions under orographic effect, was chosen to construct random surface of total storm depth. For the constructed random surface, the double Fourier analysis of the total storm depths was performed, and the principal harmonics of storm were determined. The local component, or storm residuals was obtained by subtracting the periodic component of the storm from total storm depths. It is assumed that the residuals are a sample function of a homogeneous random field. This random field can be characterized by an isotropic one dimensional autocorrelation function or its corresponding spectral density function. Under this assumption, this study proposed a theorectical model for spectral density function adapted to two watersheds.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2001.09a
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• pp.19-27
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• 2001

Seismic parameters fur computation of ground motions in Southern Korea are obtained from recently recorded data, and site-independent regional and site-dependent local strong ground motions are predicted using efficient computational techniques. For the computation of ground motions, we devised an efficient procedure to compute site-independent $x_{q}$ and dependent $x_{s}$ values separately. The first step of this procedure is to use the coda normalization method far computation of site independent Q or corresponding $x_{q}$ value. The next step is the computation of $x_{s}$, values fur each site separately using the given $x_{q}$ value. For computation of ground motions the empirical Green's function (EGF) is modified to account fur the depth and distance variations of subevents on a finite fault plane using the theoritical Green's function. It is computed using wavenumber integration technique in layered media. The site dependent ground motions at seismic stations in southeastern local area were properly simulated using the modified empirical Green's function method in layered medium. The proposed method and procedures fur estimation of site dependent seismic parameters and ground motions could be efficiently used in the low and moderate seismicity regions.ons.s.ons.

• Journal of Drive and Control
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• v.18 no.2
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• pp.20-31
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• 2021

An excavator is a construction machine that can perform various tasks such as trenching, piping, excavating, slope cutting, grading, and rock demolishing. In the 2010s, unmanned construction equipment using ICT technology was continuously developed. In this paper, the path design process was studied to implement the output data of the decision stage, and the path design algorithm was developed. For example, the output data of the decision stage were terrain data around the excavator, excavator mechanism information, excavator hydraulic information, the position and posture of the bucket at key points, the speed of the desired bucket path, and the required excavation volume. The result of the path design was the movement of the hydraulic cylinder, boom arm, bucket, and bucket edge. The core functions of the path design algorithm are the function of avoiding impact during the excavation process, the function to calculate the excavation depth that satisfies the required excavation volume, and the function that allows the bucket to pass through the main points of the excavation process while maintaining the speed of the desired path. In particular, in the process of developing the last function, the node tracking method expressed in the path design table was newly developed. The path design algorithm was verified as this path design satisfied the JCMAS H02 requirement.

• International Journal of Advanced Culture Technology
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• v.9 no.2
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• pp.18-31
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• 2021

The purpose of the present study was to present evidence for driving interventions for the elderly by conducting programs that can improve visual perception and cognitive function in a driving simulator for elderly drivers and analyse their effects. Three elderly subjects who were 65 years or older, did not have physical and cognitive impairments, and were able to drive themselves participated in the present study. A total of 12 intervention sessions, of which subjects participated in 10 sessions of nine different visual perception and cognitive function programs available in a driving simulator, were conducted and pre- and post-program assessments were conducted (two assessments in total). The assessments included the evaluation of visual perception, frontal lobe function, concentration, safe driving behaviour, and self-efficacy. The results showed positive effects of the driving simulator program on the visual perception, frontal lobe function, concentration, safe driving behaviour, and self-efficacy of all subjects. Changes in the simulator results showed remarkable improvement in the response evaluation, judgment evaluation, and predictive power evaluation, but showed difficulties in interference tasks and depth perception in common. The results showed positive effects of driving simulator training on the driving ability of the elderly, and consistent provision of such training is expected to improve the quality of life of the elderly by securing the safety of driving and actively supporting social participation.

• Journal of Environmental Science International
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• v.17 no.8
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• pp.891-898
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• 2008

This study was conducted to develop the effects of site environmental factors on estimation of site index function for Chamaecyparis obtusa Endlicher stands. We derived nonlinear growth equation and the draw site index curves by applying this estimated equation. This study with Chapman-Richards function showed significant P-value which was less then 0.0001 and $R^2$ value 0.5947. This study was conducted to develop the feasible site index equation of Chamaecyparis obtusa Endlicher. For the table, the data of 82 sample areas that were thought to be without errors among the data of Chamaecyparis obtusa Endlicher sample area located on the value-oriented forest location chart were used and estimated. After analyzing the quantification method I based on 13 environmental factors to develop the score table for the site-index estimation of Chamaecyparis obtusa Endlicher, $R^2$ value of the model was 0.7555. It has been analyzed that the scope value of Soil moisture in horizon A was 7.5045, that of total soil depth was 6.3896, that of topography was 5.3471, that of slope was 4.7000 and that of aspect was 3.2038. After analyzing the partial correlation to examine the factors that affected most the site-index of Chamaecyparis obtusa Endlicher, it has been noted that the partial correlation of climatic zone was 0.4987, which was highest, and it was followed by Soil moisture in horizon A (0.4592), slope (0.4537), topography (0.3299) and total soil depth (0.1035). As a result of conducting the significance test for partial correlation, it has been found that topography, climatic zone, parent rock, slope, altitude, aspect, Soil moisture in horizon A, soil hardness in horizon A and total soil depth were recognized significant with 1% of significance level and sedimentary type and soil texture in horizon A were recognized significant with 5% of significance level.

• Geophysics and Geophysical Exploration
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• v.17 no.2
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• pp.66-73
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• 2014

To estimate the shear-velocity ($v_s$) structure beneath the WIZ station on White Island in New Zealand, we applied receiver function (RF) inversion and H-${\kappa}$ stacking methods to 362 teleseismic events (Mw > 5.5) recorded during April 20, 2007 to September 6, 2013. Using 71 RFs with errors less than 20% after 200 iterative computations, we determined that the depth to Moho of $v_s$ = 4.35 km/s is $24{\pm}1km$ within a 15 km radius of the station. In an 1-d $v_s$ model derived by RF inversions, a 4-km thick low-velocity layer (LVL) at depths of 18 ~ 22 km was identified in the lower crust. This LVL, which is 0.15 km/s slower than the rocks above and below it, may indicate the presence of a deep magma reservoir. The H-${\kappa}$ stacking method yielded an estimate of the depth to the Moho of 24.5 km, which agrees well with the depth determined by RF inversions. The low $v_p/v_s$ ratio of 1.64 may be due to the presence of gas-filled rock or hot crystallizing magma.