• Bulletin of the Korean Chemical Society
• /
• v.5 no.6
• /
• pp.245-248
• /
• 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.

• Journal of Digital Convergence
• /
• v.15 no.7
• /
• pp.111-121
• /
• 2017

Smartphone use has become a part of everyday life, not only for adolescents but also for elderly and older people. Thus, this study explored the effect of demographic variables, the amount of smartphone usage, type of smartphone use and psychosocial variables on smartphone dependence of the elder group. We analyzed the data of 5627 (50s and 60s) of the Internet overdependence survey data of the Korea Information Society Agency in 2016. As a result of hierarchical multiple regression analysis, More frequency of smartphone use of weekday and weekend, and usage time of smartphone of weekday were related to greater smartphone dependence. More smartphone use for information seeking and games were associated with greater smartphone dependence. And, as loneliness and anxiety increased, smartphone dependence increased, while smartphone dependence decreased, as social capital increased. Through this study, it is necessary to understand characteristics related to smartphone dependence of elder and older group, and to use this knowledge to solve their smartphone dependence. Future studies also need to identify the causal relationship between predictors of smartphone dependence in elderly and older people.

• Communications for Statistical Applications and Methods
• /
• v.30 no.4
• /
• pp.369-388
• /
• 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.

• The Journal of the Korea Contents Association
• /
• v.22 no.10
• /
• pp.827-839
• /
• 2022

The severity of smartphone dependence among early adolescents, known as the most vulnerable group to smartphone addiction, is increasing. In this study, the factors affecting the smartphone dependence of early adolescents were analyzed by separating into elementary school and middle school students. For this purpose, the 1st data from Korean Children and Youth Panel Survey(2018) was used. The subjects of the study were 2,607 4th grade from elementary school and 2,590 1st grade from middle school. Factors that affect to smartphone dependence of both elementary and middle school students in common were gender, self-esteem, aggression, time spent with parents, and negative parenting attitude. On the other hand, region(city size), economic level, health status, school life satisfaction, and relationship with teachers were significant in the smartphone dependence of elementary school students, but not in middle school students. In middle school students, positive parenting attitudes were significant. Based on the results of the analysis, implications for policy establishment and social service provision were drawn to encourage the proper use of the by early youth.

• Journal of the Korean Data and Information Science Society
• /
• v.25 no.1
• /
• pp.245-254
• /
• 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.

• Journal of the Korean Institute of Telematics and Electronics B
• /
• v.31B no.3
• /
• pp.91-102
• /
• 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
• /
• v.8 no.6
• /
• pp.449-453
• /
• 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
• /
• v.12 no.4
• /
• pp.88-97
• /
• 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.

• Journal of Korean Society for Quality Management
• /
• v.42 no.4
• /
• pp.701-716
• /
• 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.

• Korean Journal of Food Science and Technology
• /
• v.44 no.3
• /
• pp.287-292
• /
• 2012

Light effects on temperature dependence of safflower oil oxidation and tocopherol degradation were studied. Safflower oil was oxidized at 20, 40, 60, or $80^{\circ}C$ for 30, 30, 15, and 6 days, respectively, in the dark or under light. Oil oxidation was evaluated with peroxide value (POV) and conjugated dienoic acid (CDA) value, and tocopherols were monitored by HPLC. Safflower oil consisted of palmitic, stearic, oleic, and linoleic acids at 7.3, 2.0, 14.2, and 76.6%, respectively, with tocopherols at 1157.1 mg/kg. Peroxide and CDA values of safflower oil increased while tocopherol contents decreased with the oxidation time and temperature. Light increased and accelerated the oil oxidation and tocopherol degradation. Temperature dependence of the oil oxidation and tocopherol degradation was higher in the dark rather than under light. The results suggest that temperature control could be more essential in the dark rather than under light with regard to the oxidative stability of safflower oil.