• Journal of the Institute of Electronics Engineers of Korea CI
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• v.49 no.4
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• pp.23-30
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• 2012

This paper proposes an improved steganalysis method to detect the existence of secret message. Firstly, we magnify the small stego noise by multiplying the speckle noise to a given image and then we estimate the denoised image by using the soft thresholding method. Because the noises are not perfectly eliminated, some noises exist in the estimated cover image. If the given image is the cover image, then the remained noise will be very small, but if it is the stego image, the remained noise will be relatively large. The parent-child relationship in the wavelet domain will be slighty broken in the stego image. From this characteristic, we extract the joint statistical moments from the difference image between the given image and the denoised image. Additionally, four statistical moments are extracted from the denoised image for the proposed steganalysis method. All extracted features are used as the input of MLP(multilayer perceptron) classifier. Experimental results show that the proposed scheme outperforms previous methods in terms of detection rates and accuracy.

• Culinary science and hospitality research
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• v.19 no.2
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• pp.52-64
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• 2013

The purposes of the study were (1) to identify the market segments of home meal replacement(HMR) consumers based on purchasing selection attributes and (2) to investigate demographic characteristics and purchasing behaviors unique to each segmented market. A total of 266 responses were used for data analysis using SPSS 19.0. Data analyses included frequency analysis, chi-square analysis, factor analysis, cluster analysis, MANOVA, and discriminant analysis. The result of the factor analysis showed four important dimensions in selection attributes: food quality, design, convenience, and accessibility. The results of the cluster analysis identified two HMR market segments, namely, highly involved HMR consumers and lowly involved HMR consumers. Highly involved HMR consumers considered all the selection dimensions more important than lowly involved HMR consumers. In addition, these two groups showed different demographic characteristics and purchasing behaviors. Managerial implications were provided.

• Proceedings of the Korea Water Resources Association Conference
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• 2011.05a
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• pp.26-30
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• 2011

최근 기후변화에 따라 강우의 패턴이 변화하고 있다. 강우일수는 줄어드는 반면, 강우강도는 증가하여, 홍수로 인한 많은 피해에 직면하고 있다. 이러한 기상이변은 홍수방어시스템을 위한 수공구조물에도 많은 영향을 미친다. 수공구조물을 설계할 때, 일반적으로 강우 기록들의 통계적 특성이 정상성을 가진다고 가정한다. 하지만 최근의 강우 자료를 분석하면, 시간에 따라 평균, 분산, 왜곡도와 같은 기본 통계량이 변화하는 것을 알 수 있다. 따라서, 수공구조물의 설계를 위한 확률 강우량은 이러한 기후변화에 따른 자료의 특성을 반영할 필요가 있다. 본 연구의 목적은 강우 자료의 비정상성의 특성을 이용하여 확률강우량을 산정하는 것이다. 최근 비정상성 강우빈도해석에 대한 연구가 활발히 진행되고 있는데, 이들 연구는 대부분 목표연도까지 경향성의 기울기가 증가, 또는 일정하다고 가정한다. 하지만, 현재는 경향성이 있지만, 목표연도에는 경향성이 없을 경우도 있고, 또는 경향성이 있어도 그 기울기가 적어지는 경향을 보일 수도 있다. 본 연구에서는 현시점과 목표연도의 시점에 대한 경향성 기울기의 변화를 고려하여 비정상성 강우빈도해석을 수행하였다. 대상지점 선정은 통계적 경향성 검정, Mann-Kendall test를 이용하여 1994년(현재시점)에 경향성이 있다고 판단되는 관측지점을 대상지점으로 선정하였다. 분석 방법은 24시간 임계지속시간의 연최대강우자료를 구축하였다. 자료를 현시점까지 선형회귀식을 이용하여 잔차 계열을 산정하고, Gumbel 분포를 이용하여 확률 잔차를 산정하였다. 확률강우량을 추정하기 위해 추세요소를 산정하였다. 기울기의 증가 혹은 감소 경향을 회귀모형을 이용하여 추세요소를 산정하였고, 잔차의 확률빈도와 추세요소의 합으로 비정상상 확률강우량을 산정하였다.

• The KIPS Transactions:PartA
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• v.8A no.3
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• pp.217-226
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• 2001

In this paper, for continuous media access operations performed by Clustered Continuous Media Storage Server (CCMSS) system, we present the analytical model based on the open queueing network, which considers simultaneously two critical delay factors, the disk I/O and the internal network, in the CCMSS system. And we derive by using the analytical model the stochastic model for the total service delay time in the system. Next, we propose the integrated stochastic admission control model for the CCMSS system, which estimate the maximum number of admittable service requests at the allowable service failure rate by using the derived stochastic model and apply the derived number of requests in the admission control operation. For the performance evaluation of the proposed model, we evaluated the deadline miss rates by means of the previous stochastic model considering only the disk I/O and the propose stochastic model considering the disk I/O and the internal network, and compared the values with the results obtained from the simulation under the real cluster-based distributed media server environment. The evaluation showed that the proposed admission control policy reflects more precisely the delay factors in the CCMSS system.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.37 no.3
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• pp.287-294
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• 2013

The roll-to-roll (R2R) printed electronics system is one of the most promising technologies for the printed electronics industry because of several advantages in terms of productivity and cost. In the R2R printed electronics system, the characteristics of the printed patterns are an important issue that determines the functional quality of the printed matter. This study analyzed how several main factors may affect the characteristics of printed patterns, especially the thickness and surface roughness. The statistical model for estimation of the printed pattern was developed as a function of the main factors using the design of experiment (DOE) methodology. Based on the statistical analysis results, the R2R printed electronics system can be designed to control the characteristics of printed patterns.

• Journal of Korean Society of Forest Science
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• v.88 no.3
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• pp.408-418
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• 1999

On the basin of RAPD analysis, genetic diversity and structure of the natural populations of Abies holophylla was estimated by AMOVA procedure. The average value of percent of polymorphic markers was 71.9%. Most variation existed among individuals within population(80.2%). Genetic differentiation among populations(${\Phi}_{ST}$) was 0.198. When the populations were grouped as two region(i.e., Taebaek and Sobaek Mountain Regions), 8.5% of the total genetic variation was explained as regional differences. The heterogeneity of molecular variance among populations was investigated with Bartlett's test, which revealed that populations of Mt. Taebaek and Mt. Gariwang were more heterogeneous. Generally, the populations of Taebaek Mountain Reion were more heterogeneous than those of Sobaek Mountain Reion. Finally, the applicability of AMOVA to the populations frenetic study was discussed in comparison with other measures of genetic differentiation which were widely used.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.1A
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• pp.87-94
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• 2010

It is widely known that cooperative spectrum sensing in which secondary users scattered in some region collaborate to detect primary users can significantly reduce the performance degradation due to the fading phenomenon. Most of previous works on cooperative spectrum sensing are based on the assumption that the local spectrum sensing decisions of secondary users are statistically independent. However, there can be practically some statistical correlation between the local decisions of any two secondary users in close proximity, which is caused by shadowing effect. In order to evaluate the effect of this correlation on the performance of collaborative spectrum sensing, we assumed that, for the case that a primary user are active in the spectrum of interest, any two local decisions are statistically correlated to each other with some level of constant correlation and independent otherwise, and analyzed the achievable throughput with the degree of correlation varying. The results showed that, as the degree of correlation gets higher, the throughput increases for the case of the AND fusion rule and decreases for the OR fusion rule.

• Korean Journal of Remote Sensing
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• v.18 no.6
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• pp.369-376
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• 2002

This paper presents a method to enhance the performance of supervised classification by separating the spectral signature of the training data sets for each class. Using clustering technique, a training data set is divided into several subsets which show a pattern of the normal distribution with small value of spectral variances. Then a supervised classification is applied with the divided training data set as training data for the temporary subclasses of the original class. The proposed method is applied to a Landsat TM image of Busan area for the applicability test. The result shows that the proposed method produces better classified results than the conventional statistical classification methods. It is expected that the proposed method will reduce the effort and expense for selecting the training data set for each class in an area which has spectrally homogeneous signature.

• Journal of the Korean Institute of Landscape Architecture
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• v.47 no.4
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• pp.1-11
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• 2019

The purpose of this study is to determine urban walking tourists' spatiotemporal movement densities and the stopping characteristics by season. With the Bukchon Hanok Village in Seoul, as the study site, a GPS-based smartphone application collected spatiotemporal data, and GIS and statistical methods were used to analyze the urban walking tourists' spatiotemporal activities in the spring and summer. The results show that the moving and staying variables of urban walking tourists differ significantly by season. In addition, spatiotemporal movement densities and stopping characteristics using ArcGIS's tools show clear spatial and temporal concentrations along the main access roads and commercial areas of the study site in the spring and summer. Policy-makers and developers of urban walking tours should use these spatiotemporal concentrations of walking tourists to define policies that would control the capacities of urban walking areas and distribute tourists spatially and temporally.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.30 no.3B
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• pp.295-303
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• 2010

The variability of vegetation is strongly related to the variability of hydrometeorological factors such as precipitation, temperature, runoff and so on. Analysis of the variability of vegetation will aid to understand the regional impact of climate change. Thus we analyzed the spatial-temporal variability of NOAA(National Oceanic and Atmospheric Administration)/AVHRR(Advanced Very High Resolution Radiometer) NDVI(Normalized Difference Vegetation Index). In the results from Mann-Kendall test, there is no significant linear trend of annual NDVI from 1982 to 2006 in the most area except the downward trend on the significance level 90% in the Guem-river basin area. In addition, using EOF(Empirical Orthogonal Function) analysis, the variability of NDVI in the region of higher latitude and altitude is higher than that in the other region since the spatial variability of NDVI follows the latitudinal gradient. Also we could get higher NDVI in June, July, August and September. We had the highest NDVI in Han-river basin area and the lowest in Je-Ju island.