• Bulletin of the Korean Chemical Society
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• 제5권6호
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• pp.245-248
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• 1984

Raman spectroscopy was used to study the reorientational motion of hexafluorobenzene in benzene and also in neutral solvents. From the viscosity dependence of the reorientation time, intermolecular interaction in the systems was investigated. No evidence was found to support the presence of long-lived 1:1 complex of hexafluorobenzene and benzene. The unusual viscosity dependence of the reorientational motion observed in the systems was explained as due to the formation of transient complexes.

• 디지털융복합연구
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• 제15권7호
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• pp.111-121
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• 2017

스마트폰의 사용은 청소년뿐만 아니라 장, 노년층에서도 일상의 한 부분이 되고 있는 것에 비해 이들을 대상으로 한 스마트폰 과의존 관련 연구는 찾아보기 어렵다. 따라서, 본 연구는 전국의 장 노년층을 대상으로 스마트폰 과의존과 관련된 변인들을 탐색하기 위해 인구사회학적 변인, 스마트폰 사용 양, 스마트폰 사용 유형과 심리 정서적 변인이 장 노년층의 스마트폰 과의존에 미치는 영향을 확인하였다. 본 연구에서는 한국정보화진흥원의 2016년 인터넷 과의존 실태조사 자료 중 50대와 60대에 해당하는 5627명의 자료를 분석하였다. 위계적 다중회귀분석 결과, 스마트폰 주중사용횟수, 주말 사용횟수, 주중사용시간이 많을수록 그리고 정보추구와 게임을 위한 스마트폰 사용이 증가할수록 스마트폰 과의존이 높았다. 반면, 오락추구와 커뮤니케이션 유형은 스마트폰 과의존에 영향을 미치지 못했다. 또한, 외로움과 불안이 증가할수록 스마트폰 과의존이 증가한 반면, 사회적 자본이 클수록 스마트폰 과의존이 낮았다. 본 연구를 통해 장, 노년층의 스마트폰 과의존과 관련된 특성들을 이해하고, 이러한 지식을 장, 노년층의 스마트폰 과의존 문제를 해결하는데 활용할 필요가 있다. 향후 연구에서는 장, 노년층의 스마트폰 과의존에 영향을 미치는 예측변인들 간의 인과관계에 대한 가설검증도 필요해 보인다.

• Communications for Statistical Applications and Methods
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• 제30권4호
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• pp.369-388
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• 2023

In this paper, we develop the two-step procedure that detects and estimates the position of structural changes for multivariate nonstationary time series, either on mean parameters or second-order structures. We first investigate the presence of mean structural change by monitoring data through the aggregated cumulative sum (CUSUM) type statistic, a sequential procedure identifying the likely position of the change point on its trend. If no mean change point is detected, the proposed method proceeds to scan the second-order structural change by modeling the multivariate nonstationary time series with a multivariate locally stationary Wavelet process, allowing the time-localized auto-correlation and cross-dependence. Under this framework, the estimated dynamic spectral matrices derived from the local wavelet periodogram capture the time-evolving scale-specific auto- and cross-dependence features of data. We then monitor the change point from the lower-dimensional approximated space of the spectral matrices over time by applying the dynamic principal component analysis. Different from existing methods requiring prior information on the type of changes between mean and covariance structures as an input for the implementation, the proposed algorithm provides the output indicating the type of change and the estimated location of its occurrence. The performance of the proposed method is demonstrated in simulations and the analysis of two real finance datasets.

• 한국콘텐츠학회논문지
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• 제22권10호
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• pp.827-839
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• 2022

스마트폰중독에 가장 취약한 집단으로 알려져 있는 초기청소년의 스마트폰의존에 대한 심각성이 증가하고 있다. 본 연구에서는 초기청소년의 스마트폰 의존도 영향요인을 초등학생과 중학생을 구분하여 분석하고자 하였다. 연구목적을 위해 2018년 한국아동청소년패널조사의 1차 조사 자료를 활용하였으며 초등학교 4학년 2,607명과 중학교 1학년 2,590명이 최종적으로 분석에 활용되었다. 초등학생과 중학생의 스마트폰의존도에 공통적으로 영향을 미치는 요인은 성별, 자아존중감, 공격성, 부모와 함께 보내는 시간, 부정적 양육태도로 나타났다. 한편 지역(규모), 경제수준, 건강상태, 학교생활만족도, 교사관계는 초등학생의 스마트폰의존도에는 유의하였으나 중학생에게는 유의하지 않았다. 중학생에게서는 부모의 긍정적 양육태도가 유의하였다. 분석결과를 바탕으로 초기청소년들의 올바른 스마트폰 사용을 장려하기 위한 정책수립 및 사회서비스제공에 대한 함의를 도출하였다.

• Journal of the Korean Data and Information Science Society
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• 제25권1호
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• pp.245-254
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• 2014

The traditional methods of simulating daily precipitation have paid little attention to the inherent dependence structure between the total precipitation amount and the precipitation frequency for a fixed period of time. To address this issue, we propose a new simulation algorithm using copula in order to incorporate the dependence into the traditional methods. The algorithm consists of two parts: First, while reflecting the observed dependence, we generate the total precipitation amount (S) and the frequency (N) during the period of interest; then we simulate the daily precipitation whose aggregation matches the pair of (N; S) generated in the first part. Our result shows that the proposed method substantially improves the traditional methods.

• 전자공학회논문지B
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• 제31B권3호
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• pp.91-102
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• 1994

For the analysis of textured image, it requires large storage space and computation time to calculate the matrix features such as SGLDM(Spatial Gray Level Dependence Matrix). NGLDM(Neighboring Gray Level Dependence Matrix). NSGLDM(Neighboring Spatial Gray Level Dependence Matrix) and GLRLM(Gray Level Run Length Matrix). In spite of a large amount of information that each matrix contains, a set of several correlated scalar features calculated from the matrix is not sufficient to approximate it. In this paper, we propose a new classifier for textured images based on these matrices in which the projected vectors of each matrix on the meaningful directions are used as features. In the proposed method, an unknown image is classified to the class of a known image that gives the maximum similarity between the projected model vector from the known image and the vector from the unknown image. In the experiment to classify images of agricultural products, the proposed method shows good performance as much as 85-95% of correct classification ratio.

• Bulletin of the Korean Chemical Society
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• 제8권6호
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• pp.449-453
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• 1987

The temperature dependence of the vibrational relaxation of NO(= 2) by NO(v = 0) has been investigated over the temperature range 100-3000 K. We have assumed that the deexcitation of NO(2) by NO(0) undergoes vibration-to-vibration (VV) energy exchange with the transfer of the energy mismatch ${\Delta}$E through rotation (R) and translation(T). The relaxation rate constants are calculated by solving the time-dependent Schrodinger equation. The sum of V-V, T, and V-V, R contributions shows very weak temperature dependence and is in reasonable agreement with observed data over the temperature range 300-3000 K.

• International journal of advanced smart convergence
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• 제12권4호
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• pp.88-97
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• 2023

Traffic flow prediction is of great significance in urban planning and traffic management. As the complexity of urban traffic increases, existing prediction methods still face challenges, especially for the fusion of spatiotemporal information and the capture of long-term dependencies. This study aims to use the fusion model of graph neural network to solve the spatio-temporal information fusion problem in traffic flow prediction. We propose a new deep learning model Spatio-Temporal Information Fusion using Graph Neural Networks (STFGNN). We use GCN module, TCN module and LSTM module alternately to carry out spatiotemporal information fusion. GCN and multi-core TCN capture the temporal and spatial dependencies of traffic flow respectively, and LSTM connects multiple fusion modules to carry out spatiotemporal information fusion. In the experimental evaluation of real traffic flow data, STFGNN showed better performance than other models.

• 품질경영학회지
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• 제42권4호
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• pp.701-716
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• 2014

Purpose: In the paper, I studied success factors and measures for win-win quality management for boosting corporate competitiveness through the achievement of high quality. Methods: As such, to that end, data of companies' win-win quality management activities and Cooperation performance were gathered. Also, I had a literature review and working staffs'opinions were gathered to develop items related to trade dependence, quality cooperation, and mutual trust and cooperation. To develop the questionnaire, sufficient literature survey was conducted, and advice was sought from experts of manufacturing companies which practice Win-Win Cooperation. Results: Based on these previous researches and analysis by structural equation modeling, among trade dependence factors, overall, other factors except financial dependence and some detailed factors were found to have a relatively significant influence relation. Conclusion: The findings of this study suggest that if individual organizations can construct an effective quality improvement system and positively pursue win-win activities, it will contribute greatly to achieving high quality and improving financial performance. However, given the time and regional limits of this study, more in-depth studies need to be conducted on measures for boosting quality competitiveness through Win-Win Cooperation.

• 한국식품과학회지
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• 제44권3호
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• pp.287-292
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• 2012

홍화씨기름의 과산화물값과 공액이중산값은 빛의 존재와 상관없이 산화시간과 산화온도가 증가함에 따라 증가했으나, 동일한 온도에서는 빛의 존재 하에서 높은 과산화물값과 공액이중산값을 보여 빛은 홍화씨기름의 산화를 촉진시켰다. 빛은 홍화씨기름 산화 및 토코페롤 분해 속도의 온도의존성을 감소시켰으며, 따라서 산화온도는 광산화에서보다는 자동산화에서 더욱 중요한 인자로 작용했다.