• Journal of Institute of Control, Robotics and Systems
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• v.15 no.12
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• pp.1216-1222
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• 2009

This article describes a simple method for generating the walking trajectory for the biped humanoid robot. The method used a simple inverted model instead of complex multi-mass model and a reasonable explanation for the model simplification is included. The problem of gait trajectory generation is to find the solution from the desired ZMP trajectory to CoG trajectory. This article presents the analytic solution for the bipedal gait generation on the bases of ZMP trajectory. The presented ZMP trajectory has Fourier series form, which has finite or infinite summation of sine and cosine functions, and ZMP trajectory can be designed by calculating the coefficients. From the designed ZMP trajectory, this article focuses on how to find the CoG trajectory with analytical way from the simplified inverted pendulum model. Time segmentation based approach is adopted for generating the trajectories. The coefficients of the function should be designed to be continuous between the segments, and the solution is found by calculating the coefficients with this connectivity conditions. This article also has the proof and the condition of solution existence.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2003.09a
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• pp.254-257
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• 2003

Statistical analysis is performed to estimate the correlations between geological or geographical factor and groundwater inflow rates in the Seoul subway system. Correlation analysis shows that among several geological and geographical factors fractures and streams have most strong effects on inflow rate into tunnels. In particular, subway line 5∼8 are affected more by these factors than subway line 1∼4. Time series analysis is carried out to forecast groundwater inflow rate. Time series analysis is a useful empirical method for simulation and forecasts in case that physical model can not be applied to. The time series of groundwater inflow rates is calculated using the observation data. Transfer function-noise model is applied with the precipitation data as input variables. For time series analysis, statistical methods are performed to identify proper model and autoregressive-moving average models are applied to evaluation of inflow rate. Each model is identified to satisfy the lowest value of information criteria. Results show that the values by result equations are well fitted with the actual inflow rate values. The selected models could give a good explanation of inflow rates variation into subway tunnels.

• Journal of Digital Convergence
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• v.13 no.3
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• pp.107-115
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• 2015

The social commerce is an innovative and emerging transaction. It is the result of combination with transaction and social media technology. This study analyzes Korean college students' social commerce behavior through extending technology acceptance model(TAM) with social influence(SI). We confirmed all proposed hypotheses are significant and supported by the given data through PLS path modeling method with SmartPLS. It indicates that SI is an important factor influencing intention to use, so SI should be consider for theorists to enhance explanation and prediction of TAM and for practitioners to earn higher performances as well. Finally, based on the findings, suggestions for future studies are discussed.

• The Journal of Industrial Distribution & Business
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• v.7 no.4
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• pp.11-16
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• 2016

Purpose - There are numerous theories for retail trade area analysis which are designed to select candidate locations for new stores. In this study, comparative analysis on the characteristics from those of the theories are shown, and the explanation for the power in consumers' store-choice behaviors and their limitations are examined. Also, plans for improving commercial sphere analysis are explored. Research design, data, and methodology - This study is based on literature reviews with normative research methodology. Among many researches regarding the analysis on the location and commercial sphere for launching a new store, researches relying on statistics are excluded in this study since they belong to the marketing research area,. Results - In the Law of retail gravitation, Huff's model multinomial logit model and etc. are mutual complementary mathematical techniques for analyzing commercial spheres and each of them has its own characteristics. These theories rely on the same hypothesis in which consumers are all believed to be behaving rationally under a similar behavioral system. However, the trial in explaining or estimating behavior of choosing a store with only a select size of the population that is objectively estimated by some major properties has limits in its credibility. Conclusion - Research on consumer's spatial behaviors can be fully illustrative and explainable when it has both quantitative approaches such as 'law of retail gravitation', 'logit model' and etc., and qualitative approaches like consumer's 'cognitive structure', 'learning status', 'image formation', 'attitude' and etc.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2022.05a
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• pp.484-487
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• 2022

This study suggests an XAI-based machine learning method to predict the productivity of tight oil reservoirs according to the production period. The XAI algorithm refers to interpretable artificial intelligence and provides the basis for the predicted result and the validity of the derivation process. In this study, we proposed a supervised learning model that predicts productivity in the early and late stages of production after performing data preprocessing based on field data. and then based on the model results, the factors affecting the productivity prediction model were analyzed using XAI.

• Nuclear Engineering and Technology
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• v.56 no.1
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• pp.233-240
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• 2024

The wall friction correlations of oscillatory natural circulation loops are highly loop-specific, making it difficult to perform 1-D system simulations before obtaining specific experimental data. To better predict the friction characteristics, the nonlinear dynamics of a toroidal single-phase natural circulation loop were numerically investigated, and the transition effect was considered. The k-k_L-ω transitional turbulence and k-ω SST turbulence models were used to compute the flow characteristics of the loop under different heating powers varying from 0.48 to 1.0 W/cm², and the results of both models were compared with previous experiments. The mass flow rates and friction factors predicted by the k-k_L-ω model showed a better agreement with the experimental data than the results of the k-ω SST model. The oscillation frequencies calculated using both models agreed well with the experimental data. The k-k_L-ω transitional turbulence model provided better friction-factor predictions in oscillatory natural circulation loops because it can reproduce the temporal and spatial variation of the wall shear stress more accurately by capturing the movement of laminar, transition turbulent zones inside unstable natural circulation loops. This study shows that transition effects are a possible explanation for the highly loop-specific friction correlations observed in various oscillatory natural circulation loops.

• Journal of the Korean Chemical Society
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• v.67 no.5
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• pp.378-392
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• 2023

The purpose of this study is to analyze the pre-service chemistry teachers' cognition of the nature of model in process of designing and developing models using technology. For this purpose, 19 pre-service chemistry teachers' in the 3rd grade of a education college located in the central region observe experimental phenomena related to Boyle's law presented in the 7th grade science textbook and researchers required the design and development of a model related to the observed experimental results using technology. Based on previous studies, the nature of model were classified into two aspect: 'Representational aspect' and 'Explanatory aspect'. The 'Representational aspect' was classified into 'Representation', 'Abstraction', and 'Simplification', and the 'Explanatory aspect' was classified into 'Analysis', 'Interpretation', 'Reasoning', 'Explanation', and 'Quantification'. The pre-service chemistry teachers' cognition were analyzed by the classification. As a result of the study, the 'Representation' of the 'expressive aspect' was uniformized in the form of space that changes in volume, and the pressure was expressed as the Brightness inside the cylinder or frequency of color change of particles for 'Abstraction'. In the case of 'Simplification', the particle collision was expressed as a perfectly elastic collision, but there was a group that could not simply indicate the type of particle. In the 'Explanatory aspect', in the case of 'Analysis', volume was classified as a manipulated variable, and in the case of 'Interpretation', most groups analyzed the change in pressure through the collision of gas particles. However, the cognition involved in 'Reasoning' was not observed much. In the case of 'Explanation', there were groups that did not succeed in explanation because the area where the particles collided was not set or incorrectly set, and in the case of 'Quantification', there was a group that formulated the number of collisions per unit time, and on the contrary, there was a group that could not quantify the number of collisions because they could not be expressed in numbers.

• Journal of Korean Academy of Nursing Administration
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• v.6 no.2
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• pp.259-279
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• 2000

This study is a descriptive analytic research measuring nursing service quality, using SERVQUAL model, to make fundamental data and strategies for nursing service improvement. Data were collected by self-reported questionnaire from 202 patients and 142 nurses, from June 7 to 14, 1999. The reliability of instrument were adequate(Cronbach ${\alpha}=.94$). SAS program was utilized for statistical analysis of collected data. The results were as follows; 1. There was a gab between patient's expectation and perception on nursing service(Gap B). Gap D was indicated an affecting factor to decide nursing service quality. Gap C was indicated an indirect affecting factor of nursing service quality. Because it was not statistically significant in total item analysis, but in individual item analysis, 7 items were appeared statistically significant. Gap A was not a gap occurrence factor of nursing service quality. 2. Focuses of nursing service quality improvement strategies were; (1) to direct qualitative improvement of nursing service in order to correspondence patient's nursing service expectation. (2) to make nurse's service activity modified because nurse's practice were not reached patient's expectation level. (3) to need internal, external factor analysis affecting nurse's service activity. 3. Nursing service quality was decided by rather environmental inappropriateness provided nursing service than itself. Therefore, to make nursing service quality improvement, it is required to improve nursing service environment. For this, followings are required; (1) to strengthen nurse's education on lower part of nursing service satisfaction and QI activities. (2) to balance demand and supply of nursing personnel. 3) to fix computerized system for reducing other duties weight except nursing care through analysis of nursing activity. (4) to construct rational cooperating system among related departments. 4. The important parts for nursing service quality improvement were indicated as follows: (1) Gap B: 'prompt reaction', 'examination symptom before patient's complaint', 'hearted nursing service reducing patient's dissatisfaction', 'explanation goals of nursing activities', 'having special Knowledge enough', 'maintenance position comfortably', 'management of patient's physical hygiene'. (2) Gap C: 'maintenance physical safety', 'explanation about hospital rules and facilities'. (3) Gap D: 'tender, safe injection and wound care'. Because above items are mostly improved through nurse's attitude change and quality improvement, it is required to establish nursing standardization and to strengthen nurse's clinical education. As the based on above results, followings are suggested; 1. SERVQUAL model is very useful to make strategies for nursing service quality improvement because it indicates multiple factors affecting hap occurrence. 2. At individual items analysis of Gap C, statistically significant 7 items appeared higher nurse's perception level than patient's perception level on nursing service were trouble perception level on nursing service quality improvement. So. it need further research to analysis about these difference occurring factors. 3. At analysis of Gap D, it is indicated that in nursing service performance process, multiple factors lowing nursing service quality were intruded. So it needs further research to analysis what these factors are and how each factors affect on nursing performance process. 4. nursing service quality measurement is changeable according to sample select time or sampled subject's characteristics. So to develope strategy for nursing service quality improvement is based on the results of periodical analysis.

• Journal of The Korean Association For Science Education
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• v.37 no.1
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• pp.155-168
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• 2017

This study investigates how elementary students used cognitive-emotional rebuttals in the context of modeling activities, especially on how their emotional and cognitive processes lead them to use rebuttals in terms of epistemic affect. Twenty-five fifth grade elementary students participated in the study as part of their science class. During the course of their sixth periods, students constructed a human respiratory system model through continuous discussion. The research results showed that elementary students used an elaboration-oriented rebuttal, a defence-oriented rebuttal, and a blame-oriented rebuttal in their modeling activity. The elaboration-oriented rebuttal interspersed with negative epistemic affect was used to elaborate on a student's explanation, and a negative epistemic affect was elicited from their cognitive discrepancy. On the other hand, defence-oriented rebuttal and blame-oriented rebuttal entangled with negative epistemic affect were used to defeat the students rather than help rigor evaluation of students' explanation, and the negative epistemic affect was elicited from the other students' undesirable behavior. These results suggest that students' rebuttals can be elicited by epistemic dynamics related to the epistemic affect. The study shows that if negative epistemic affect were elicited from the other students' naive or false explanations, such an emotion is natural in terms of model construction, and the model can be further developed through the acceptance of the elaboration-oriented rebuttals by students' emotion regulation. In addition, we suggest that negative emotions aroused from the worsening of relationships during small group modeling activities are difficult to regulate and can have negative effects on students' cooperative model construction.

• The Journal of the Korea Contents Association
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• v.13 no.11
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• pp.726-739
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• 2013

The purpose of this paper is to assert the necessity of social health as a solution to resolve social issues of the aged in the nearing aged society, and to assess the effects that the social health of the aged has on their quality of life. In doing so, the study gathered as its study subjects those aged persons who participate in social activities among persons aged 65 or older who reside in Euiwang-si, Gyeonggi-do. A total of 157 subject studies were used for the final analysis. An analysis of frequency, t-Test and one-way ANOVA, Duncan post-test, correlation analysis and hierarchical regression analysis was conducted by using the IBM SPSS 21.0. The main study findings are as follows. with respect to the correlation between socio-demographic factors and social health, economic level, subjective level of health and social health showed a positive correlation. Domiciliary treatment level and subjective level of health showed a negative correlation with economic level and social health, respectively. with respect to the effects of social health on quality of life, in the case of model 1 which only input factors of socio-demographical characteristics, the variance explanation power was found to be 38.2% and the regression model was found to be significant (F=13.141, p<.001). In the case of model 2 which input factors of socio-demographical characteristics and social health, the variance explanation power was found to be 13.8% and the regression model was found to be significant (F=20.057, p<.001). Based on such study results, this study recommends a number of proposals.