• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2003.09a
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• pp.227-230
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• 2003

시계열 분석 기법을 통하여 창원시 대산면 갈전리 강변여과수 취수지역의 지하수위와 하천수위와의 연관성을 살펴보았다. 연구지역의 6개 관측공의 30분 간격의 지하수위의 자기상관성을 분석한 결과, 세 개의 그룹으로 나타난다. 이 세 그룹은 낙동강으로부터 가까운 거리에 있으며 강한 자기상관성을 보이는 그룹(1그룹), 하천으로부터 비교적 가깝고 양수정으로부터 떨어져 있는 그룹(2그룹), 그리고 약한 자기상관성을 보이는 그룹(3그룹)으로 나타난다. 1그룹이 강한 자기상관성을 보이는 것은 낙동강의 영향 때문인 것으로 판단되며, 3그룹의 약한 자기상관성은 취수정의 양수의 영향으로 판단된다. 6개 관측공 지하수위와 낙동강 수위의 교차상관분석을 실시한 결과, 교차상관함수가 0.1이하의 낮은 교차상관성을 보이고 있다. 이는 취수정의 양수에 의한 관측공의 수위변동에 의해서 낙동강 수위와의 연관성이 잘 나타나지 않기 때문이다.

• Journal of Korean Society for Geospatial Information Science
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• v.24 no.1
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• pp.25-33
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• 2016

In order to visualize point based Location-Based Social Network Services(LBSNS) data on multi-scaled tile map effectively, it is necessary to apply tile-based clustering method. Then determinating reasonable numbers and size of tiles is required. However, there is no such criteria and the numbers and size of tiles are modified based on data type and the purpose of analysis. In other words, researchers' subjectivity is always involved in this type of study. This is when Modifiable Areal Unit Problem(MAUP) occurs, that affects the results of analysis. Among LBSNS, geotagged Twitter data were chosen to find the influence of MAUP in scale effects perspective. For this purpose, the degree of spatial autocorrelation using spatial error model was altered, and change of distributions was analyzed using Morna's I. As a result, positive spatial autocorrelation showed in the original data and the spatial autocorrelation was decreased as the value of spatial autoregressive coefficient was increasing. Therefore, the intensity of the spatial autocorrelation of Twitter data was adjusted to five levels, and for each level, nine different size of grid was created. For each level and different grid sizes, Moran's I was calculated. It was found that the spatial autocorrelation was increased when the aggregation level was being increased and decreased in a certainpoint. Another tendency was found that the scale effect of MAUP was decreased when the spatial autocorrelation was high.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.3
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• pp.1148-1156
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• 2013

The purpose of this study is to investigate the relationship among self-efficacy, motivation proposed by self-determination theory and academic achievement and to confirm the relative predictive power of motivation variables in predicting 480 middle/high students' achievement. The instruments used in this study were 'Self-efficacy' and 'Self - regulation' scale. The data were analyzed with Pearson correlations and multiple regression (stepwised) analysis. The correlations among self-efficacy, self-determination motivation and academic achievement were significant. The variables among self-determination were correlated to academic achievement in middle school. Among the variables of self-determination motivation, identified regulation, Integrated regulation and intrinsic regulation were positively related to academic achievement in high school but amotivation was negatively related to academic achievement. Self-control efficacy and self-confidence were the significance predictor of academic achievement in middle school. Hard-task preference and self-control efficacy were the significance predictor of academic achievement in high school students. Introjected-regulation was the best predictor of academic achievement in middle school. Identified-regulation was the best predictor of academic achievement in high school.

• Proceedings of the Korean Society of Disaster Information Conference
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• 2016.11a
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• pp.261-262
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• 2016

교통사고의 발생요인에는 다양한 원인들이 있지만 본 연구에서는 공간적으로 접근하여 사고유형별 분포특성을 도출하기 위해 공간적 자기상관성 분석을 수행하였다. 논문에서는 2012년부터 2014년까지 울산광역시에서 발생된 교통사고를 대상으로 분석을 수행하였다. 그 결과 울산시 전체 교통사고 약 53%는 안전운전불이행이며 다음으로는 안전거리미확보, 신호위반 순으로 나타났다. 밀도분석 결과는 사고유형별로 분포가 차이가 있었으며 안전운전불이행의 경우 가장 큰 군집은 중심시가지인 달동과 삼산동 중심에 나타났으며 중앙선침범은 도시의 중심부 보다는 면지역에 넓게 퍼져서 발생되었으며 산업단지가 있는 동구지역에 군집이 크게 나타났다. 따라서 읍면동별 공간적 특성을 파악하기 위해 Moran's I분석과 LISA분석을 수행한 결과 안전운전불이행, 안전거리미확보, 신호위반, 교차로운행방해 모두 중심시가지인 신정동, 달동, 삼산동이 공간적 자기상관성이 높았으며 중앙선침범의 경우 밀도분석 결과와 마찬가지로 중심시가지 이외에 읍면 지역도 자기상관성이 더 높게 나타났다. 이를 통해 사고유형별 공간의존성 및 이질성을 파악하여 교통사고 다발지역을 도출하고 이를 토대로 지역특성에 맞는 저감 대책 마련에 활용되고자 한다.

• Review of KIISC
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• v.2 no.3
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• pp.41-49
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• 1992

레이다 시스템, ranging 시스템, 확산 대역 통신 (spread spectrum communication) 시스템, 그리고 요즈음 각광받고 있는 코드분할방식 다중통신 (CDMA com-munication) 시스템에서는 주지하다시피 상관성(correlation) 이 좋은 수열(sequence)들위 사용이 필수 불가결하다. 수열의 상관성은 그 수열 자신의 상관성이냐 다른 수열간의 상관성이냐에 따라 자기상관관계(crosscorrelation)로 나누어 생각할 수 있고 수열의 주기성의 유무에 따라 주기적 상관관계(Periodic correlation)와 비주기적 상관관계(aperiodic correla-tion)로 나누어 볼 수 있다. 여기서 수열의 상관성이 좋다는 말은 정규화된 수열의 자기상관계수(autocorrelation coefficient)와 수열 간의 교차상관 계수(crosscorrelation coefficient)의 최대 크기가 수열의 길이에 비해 상대적으로 작은 값을 갖는다는 것을 의미한다. 본 논문에서는 주기성을 갖는 이진수열군의 하나인 bent수열과 이 bent수열을 구성하는데 기본이 되는 bent함수를 중심으로 주기적 상관성이 우수한 여러 수열군에 대해 알아보고자 한다.

• Journal of Digital Convergence
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• v.16 no.10
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• pp.89-99
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• 2018

The purpose of this study is to analyse the determinants of the change in the welfare expenditure of local governments in 2015. This study analyzed the spatial correlation of welfare expenditure among neighboring local governments and determined the factors affecting the welfare expenditures. According to the results of the study, spatial correlation of welfare expenditure among local governments appears. Determinants, such as socio-economic factors, administrative factors, public financial factors are affecting the amount of the welfare expenditures, but local political factors, and local tax, last year's budgets are not correlated with the amount of local welfare expenditures. In this study, it is significant to found out that the spatial correlation of welfare expenditure among the local governments and to examine the determinants. If possible, it is necessary to analyze the time-series analysis using the multi-year welfare expenditure data, expecially self-welfare expenditures.

• Communications for Statistical Applications and Methods
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• v.19 no.3
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• pp.507-516
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• 2012

We study time series models for seasonal time series data with a covariance structure that depends on time and the periodic autocorrelation at various lags $k$. In this paper, we introduce an ARMA model with periodically varying coefficients(PARMA) and analyze Arosa ozone data with a periodic correlation in the practical case study. Finally, we use a PARMA model and a seasonal ARIMA model for data analysis and show the performance of a PARMA model with a comparison to the SARIMA model.

• Proceedings of the IEEK Conference
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• 2000.09a
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• pp.799-802
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• 2000

음성신호처리 분야에서 음성신호의 기본 주파수를 정확히 검출 할 수 있다면 음성인식을 할 때 화자에 따른 영향을 줄일 수 있으므로 인식의 정확도를 높일 수 있고, 음성합성을 할 때 자연성과 개성을 쉽게 변경하거나 유지할 수 있다. 또한 분석을 할 때 피치에 동기시켜 분석하면 성문의 영향이 제거된 정확한 성도 파라미터를 얻을 수 있다. 위와 같은 피치검출의 중요성 때문에 피치검출에 대하여 다양한 방법 이 제안되었다〔1〕. 본 논문에서는 음성신호의 분석 시 불안정한 구간에 대해 피치 시점을 검출하는 방법을 연구하였다. 음성신호의 분석에 있어서 기존의 자기상관함수법(Autocorrelation Function)은 주기성을 강조할 수 있다는 장점을 가지고 있다. 그러나 자기상관함수는 위상성분을 보존하지 못한다는 단점을 가지고 있다. 따라서, 자기상관함수를 사용하면서 위상성분을 보존할 수 있는 알고리즘을 제안하고자 한다. 실험결과 피치시점을 수동으로 찾은 경우와 비교하였을 때 약 98% 정도의 정확도를 얻을 수 있었다. 위의 결과와 같이 위상 성분이 보존된 자기상관함수를 사용할 경우 음성합성, 코딩, 인식에서 유용하게 쓰일 수 있다.

• Journal of Digital Convergence
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• v.18 no.11
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• pp.311-318
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• 2020

This study was done to explore the correlation among self-determination, learning commitment and learning outcomes and identify factors related learning outcomes under academic credit bank system. The survey was conducted self-report questionnaire. The data collection period was form April to November 2018. Participants were 144 registered nurses working currently under academic credit bank system. Collected data were analyzed using SPSS/WIN 24.0. Learning outcomes had a positive correlation with self-determination and learning commitment. learning commitment. Self-determination was positively correlated learning commitment. Factors affecting learning outcomes included self-determination and learning commitment. And self-determination and learning commitment accounted for 32.1% of the variance in learning outcomes. Therefore, developing learning outcomes support for improving self-determination and learning commitment. Future research will be needed to clarify the effects of learning outcomes promotion program on self-determination and learning commitment.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.36 no.4
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• pp.723-733
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• 2016

This study aims to analyze the effects of urban characteristics on the amount of damage caused by natural disasters. It is focused on the areas of a municipal level in Korea. Also, it takes into account the spatial autocorrelation of the damage caused by natural disasters. Moran's I statistics was estimated to examine the spatial autocorrelation in the damage from the study area. Subsequent to evaluating the suitability for spatial regression models and the OLS regression model, the spatial lag model was employed as an empirical analysis for the study. It showed that the increase in residential area leads to the decrease in the amount of natural disaster damage. On the other hand, the increase in green area and river basin is associated with the increase in the damage. As a result of empirical analysis, appropriate policy establishment and implementation about the damage-adding factors is needed in order to reduce the amount of damage in the future.