• The Journal of the Korea Contents Association
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• v.19 no.4
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• pp.682-689
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• 2019

This study aims to spatialize the gap between obesity levels through the body mass index, an objective indicator of the level of health among vulnerable people. Thus, areas where the BMI showed cluster patterns with spatial high and low values were extracted and the characteristics of the region were analyzed. The analysis showed that the I statistics for the obesity rate were 0.07 and the z-score was 4.39, confirming spatial autocorrelation. For z-score, it was much larger than the maximum threshold of 2.57. This means that the rate of obesity among the socially vulnerable is regional, and this gap is spatially significant. The results of comparing and analyzing the local environment for these areas of obesity and health care were found to be areas with poor public transportation, less readily available parks, and a concentration of single and multi-generation housing. The analysis results of this study are meaningful in that they provide spatial implications for the health of the socially vulnerable class that previous studies have neglected.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.40 no.6
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• pp.400-407
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• 2003

In this paper an optical encryption system, which can decrypt the original image by using the autocorrelation terms of a JTC, is proposed. Unlike the classical JTC, the joint input plane of the proposed system is composed in a frequency domain not a spatial domain, thus it needs only one Fourier transformation. To use like this, the phase component appeared in the output plane of JTC should be considered. We presents the effect of phase and provides the solution. An original image is encrypted to a complex-valued random image. The original image is reconstructed using the autocorrelation terms which is the main drawback of JTC, therefore the proposed system is more suitable for JTC and real time processing. By computer simulation and optical experiment, the analysis for the phase effect and the performance of the proposed system are confirmed.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.9
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• pp.1818-1825
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• 2017

An Acoustic Doppler Current Profiler(ADCP) measures the current velocity and analyzes the degree of turbulence using Doppler effects of ultrasonic waves. Therefore, the autocorrelation or FFT spectrum estimates are obtained for extraction of current velocity in each spatial region. However, if the correlation method does not satisfy the assumption that the return signal spectra are symmetric Gaussian, the large bias errors can occur. Also, the accurate estimation of autocorrelation or FFT spectrum is difficult due to the short acquisition interval when the rapid changes of current velocity occur. Thus, in this paper, the estimation method of the autoregressive spectrum peak is suggested for the accurate current velocity measurement of both symmetric and asymmetric spectra. It is shown that estimation quality can be improved using the suggested method comparing with the conventional methods. Many return signals under the various environment are simulated and the results are compared and analyzed for evaluation of the suggested method.

• Journal of Advanced Marine Engineering and Technology
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• v.10 no.3
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• pp.107-118
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• 1986

The presenet research attempts to examine the combustion characteristics and the structure of the flame in turbulent premixed flames and thus enhance the combustion performance that leads to the design of the effective combustion system (untilizing LNG). Following experimental investigations for several stabilized premixed flames were attempted to identify the interactive mechanism between flame structures and flow fields; Visualization by Schlieren method, measurement of flow velocity by LDV, detection of ion current by ion probe, measurement of fluctuating temperature by thermocouple having compensation circuit, average values with respect to time of fluctuating amount for flow velocity, temperature, ion current, etc., variable RMS values, PDFs, autocorrelation, crosscorrelation, spatial macroscale, power spectra, and velocity scale. Continuing the authors published studies whose flame dominated by coherent structures and the characteristics of combustion reaction for irregular three dimensional flame and stabilized flame by step were investigated with obtained experimental quantities. Results of this research are following : The most turbulent flames support the structure of a Wrinkled laminar flame or laminar flamelets. It also observed that combustion reaction is related to small tubulence microscales of the turbulent flow fields closly.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2004.10a
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• pp.11-18
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• 2004

In this paper, an efficient model reduction scheme is presented for large scale dynamic systems. The method is founded on a modal analysis in which optimal eigenvalue is extracted from time samples of the given system response. The techniques we discuss are based on classical theory such as the Karhunen-Loeve expansion. Only recently has it been applied to structural dynamics problems. It consists in obtaining a set of orthogonal eigenfunctions where the dynamics is to be projected. Practically, one constructs a spatial autocorrelation tensor and then performs its spectral decomposition. The resulting eigenfunctions will provide the required proper orthogonal modes(POMs) or empirical eigenmodes and the correspondent empirical eigenvalues (or proper orthogonal values, POVs) represent the mean energy contained in that projection. The purpose of this paper is to compare the reduced order model using Karhunen-Loeve expansion with the full model analysis. A cantilever beam and a simply supported plate subjected to sinusoidal force demonstrated the validity and efficiency of the reduced order technique by K-L method.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.21 no.12
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• pp.1679-1689
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• 1997

In this paper, a precise description is given to the basic theory as well as the detailed algorithms for the numerical treatment of the method of POD (proper orthogonal decomposition). This method is then applied to analysing the numerical solutions of one-dimensional shallow-water equations to show how the method is affected by various parameters such as the sampling time, sampling numbers, and the spatial resolution for the autocorrelation function. A few curious features associated with this flow model found through the analysis are further explained and discussed.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.30B no.4
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• pp.44-55
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• 1993

In this paper, we proposed a new optical method for the efficient recognition of Korean characters. There are six filters in the proposed method which employed the concepts of amplitude-modulated phase-only filter(AMPOF) and spatial frequency modulation(SFM). Here, amplitude modulation is used to achieve improved correlation discrimination and SFM is to reduce the number of filters. We also used a simplified synthetic discriminant function(SDF) for distortion invariance of input image. In order to recognize the partial rotation invariant Korean characters, the proposed distortion invariant minimum average correlation energy (MACE) filter is synthesized SFM, partial rotation invariant filter (PRIF), AMPOF and MACE for partial rotation invariance in the frequency domain. The advantage of the proposed filters is to supress the sidelobes of cross correlation peak away from the autocorrelation peak and to produce sharp correlation peaks. We performed simulation and optical experiment for some of Korea characters using the proposed method. The results show that the proposed method has more improved discriminant ability and reduced processing time than the conventional methods.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.29 no.1
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• pp.29-37
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• 2011

The purpose of this research is to measure Quality of Life indices using Factor Analysis and Principle Component Analysis and to analyze the spatial patterns of Quality of life distribution in the Seoul Metropolitan Area in terms of spatial association using spatial statistics and spatial exploratory technique. In order to check the degree of clustering, this study used spatial autocorrelation indices, global Moran's I index. In addition, local scale analysis was conducted using Moran Scatterplot and Local Moran's I to identify the spatial association pattern and the high Quality of life. The analysis based on global statics showed that, in the Seoul Metropolitan Area, QoL Indices had been distributed with positive spatial association. According to the local spatial statistics, the general tendency of clustering H-H clusters which were mainly concentrated on the Seoul, L-H clusters were concentrated on the Kyunggi-Do and L-L Clusters showed the regional extent of lagging behind. However, in case of H-H, L-H Clusters they had been spread out in the Newtown as population increase.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.38 no.4
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• pp.295-304
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• 2020

The IPCC (Intergovernmental Panel on Climate Change) recommended the importance of preventive measures against extreme weather, and heat waves are one of the main themes for establishing preventive measures. In this study, we tried to analyze the heat vulnerable areas by considering not only spatial characteristics but also social characteristics. Energy consumption, popu lation density, normalized difference vegetation index, waterfront distance, solar radiation, and road distribution were examined as variables. Then, by selecting a suitable model, SLM (Spatial Lag Model), available variables were extracted. Then, based on the Fuzzy theory, the degree of vulnerability to heat waves was analyzed for each variable, and six variables were superimposed to finally derive the heat vulnerable area. The study site was selected as the Daegu area where the effects of the heat wave were high. In the case of vulnerable areas, it was confirmed that the existing urban areas are mainly distributed in Seogu, Namgu, and Dalseogu of Daegu, which are less affected by waterside and vegetation. It was confirmed that both spatial and social characteristics should be considered in policy support for reducing heat waves in Daegu.

• Journal of Korean Society for Geospatial Information Science
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• v.23 no.3
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• pp.77-84
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• 2015

The key objective of this research is to review the effectiveness of spatial regression to identify the influencing factors of spatial distribution patterns of floating population. To this end, global and local spatial autocorrelation test were performed using seoul floating population survey(2014) data. The result of Moran's I and Getis-Ord $Gi^*$ as used in the analysis derived spatial heterogeneity and spatial similarities of floating population patterns in a statistically significant range. Accordingly, Geographically Weighted Regression was applied to identify the relationship between land use attributes and population floating. Urbanization area, green tract of land of micro land cover data were aggregated in to $400m{\times}400m$ grid boundary of Seoul. Additionally public transportation variables such as intersection density transit accessibility, road density and pedestrian passage density were adopted as transit environmental factors. As a result, the GWR model derived more improved results than Ordinary Least Square(OLS) regression model. Furthermore, the spatial variation of applied local effect of independent variables for the floating population distributions.