• Title/Summary/Keyword: Statistical Model

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Multi-fidelity uncertainty quantification of high Reynolds number turbulent flow around a rectangular 5:1 Cylinder

  • Sakuma, Mayu;Pepper, Nick;Warnakulasuriya, Suneth;Montomoli, Francesco;Wuch-ner, Roland;Bletzinger, Kai-Uwe
    • Wind and Structures
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    • v.34 no.1
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    • pp.127-136
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    • 2022
  • In this work a multi-fidelity non-intrusive polynomial chaos (MF-NIPC) has been applied to a structural wind engineering problem in architectural design for the first time. In architectural design it is important to design structures that are safe in a range of wind directions and speeds. For this reason, the computational models used to design buildings and bridges must account for the uncertainties associated with the interaction between the structure and wind. In order to use the numerical simulations for the design, the numerical models must be validated by experi-mental data, and uncertainties contained in the experiments should also be taken into account. Uncertainty Quantifi-cation has been increasingly used for CFD simulations to consider such uncertainties. Typically, CFD simulations are computationally expensive, motivating the increased interest in multi-fidelity methods due to their ability to lev-erage limited data sets of high-fidelity data with evaluations of more computationally inexpensive models. Previous-ly, the multi-fidelity framework has been applied to CFD simulations for the purposes of optimization, rather than for the statistical assessment of candidate design. In this paper MF-NIPC method is applied to flow around a rectan-gular 5:1 cylinder, which has been thoroughly investigated for architectural design. The purpose of UQ is validation of numerical simulation results with experimental data, therefore the radius of curvature of the rectangular cylinder corners and the angle of attack are considered to be random variables, which are known to contain uncertainties when wind tunnel tests are carried out. Computational Fluid Dynamics (CFD) simulations are solved by a solver that employs the Finite Element Method (FEM) for two turbulence modeling approaches of the incompressible Navier-Stokes equations: Unsteady Reynolds Averaged Navier Stokes (URANS) and the Large Eddy simulation (LES). The results of the uncertainty analysis with CFD are compared to experimental data in terms of time-averaged pressure coefficients and bulk parameters. In addition, the accuracy and efficiency of the multi-fidelity framework is demonstrated through a comparison with the results of the high-fidelity model.

An Empirical Study on the Factors Affecting Continuous Usage Intention of Games (게임의 지속적 이용에 영향을 미치는 요인에 대한 실증적 연구)

  • Kim, Han-Min;Kim, Jong Uk;Park, Sang Cheol
    • Journal of Digital Convergence
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    • v.20 no.5
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    • pp.525-535
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    • 2022
  • The purpose of this study is to identify the factors influencing the user's continuous usage intention of computer games. A research model was developed which shows that the independent variables of value, expectation confirmation, perceived enjoyment affect user satisfaction and continuous usage intention. To test the six hypotheses, survey data were collected from 104 respondents, and hypotheses tests as well as a confirmatory factor analysis were conducted using a partial least square analysis tool. The statistical analysis result showed that expectation confirmation had a significant positive effect on satisfaction, and satisfaction also had a strong positive effect on the game user's continuous usage intention. Perceived enjoyment showed a highly strong positive effect on satisfaction. In addition, satisfaction was found to have full mediation effects in the relationship between expectation confirmation and continuous usage intention, and perceived enjoyment and continuous usage intention respectively. This result provides an important implication that continuous usage intention occurs through user satisfaction, and also indicates the contribution of this study for the game industry. Another contribution of this study is to introduce critical independent variables from the marketing and information technology domains in order to explain continuous usage intention of computer games.

A study of artificial neural network for in-situ air temperature mapping using satellite data in urban area (위성 정보를 활용한 도심 지역 기온자료 지도화를 위한 인공신경망 적용 연구)

  • Jeon, Hyunho;Jeong, Jaehwan;Cho, Seongkeun;Choi, Minha
    • Journal of Korea Water Resources Association
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    • v.55 no.11
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    • pp.855-863
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    • 2022
  • In this study, the Artificial Neural Network (ANN) was used to mapping air temperature in Seoul. MODerate resolution Imaging Spectroradiomter (MODIS) data was used as auxiliary data for mapping. For the ANN network topology optimizing, scatterplots and statistical analysis were conducted, and input-data was classified and combined that highly correlated data which surface temperature, Normalized Difference Vegetation Index (NDVI), Enhanced Vegetation Index (EVI), time (satellite observation time, Day of year), location (latitude, hardness), and data quality (cloudness). When machine learning was conducted only with data with a high correlation with air temperature, the average values of correlation coefficient (r) and Root Mean Squared Error (RMSE) were 0.967 and 2.708℃. In addition, the performance improved as other data were added, and when all data were utilized the average values of r and RMSE were 0.9840 and 1.883℃, which showed the best performance. In the Seoul air temperature map by the ANN model, the air temperature was appropriately calculated for each pixels topographic characteristics, and it will be possible to analyze the air temperature distribution in city-level and national-level by expanding research areas and diversifying satellite data.

A Study on the Influence of Augmented Reality Experience in Mobile Applications on Product Purchase (모바일 어플리케이션의 증강현실 이용경험이 제품구매에 미치는 영향 연구)

  • Kim, Minjung
    • The Journal of the Convergence on Culture Technology
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    • v.8 no.6
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    • pp.971-978
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    • 2022
  • As a marketing method in a non-face-to-face society, the purpose of this study is to test how AR experience affects purchase intention in the process of consumers recognizing product information to purchase products and to secure the basis for the effectiveness of developing and introducing augmented reality functions in future product brand applications. Literary research methods and empirical research methods were used to verify the research purpose, and to measure this, an application of domestic tableware brand 'Odense', which implements augmented reality functions, was produced and used as an experimental tool. Also, a direct causal relationship was attempted by constituting a questionnaire by deriving a measurement scale for perceived usefulness, perceived ease, perceived pleasure, and purchase, which are factors of technology acceptance theory (TAM), and empirical analysis was conducted using the SPSS 25.0 statistical package to achieve the purpose of the study. As a result of the study, significant results were derived from all factors in the effect of perceived usefulness, ease, and pleasure on purchase intention, and several significant differences were found among factors according to gender, age, and internet shopping usage time in general characteristics. In conclusion, the user experience of the medium in which the augmented reality function is introduced in the information recognition stage of the product has a positive effect on purchase compared to the user experience of existing applications.

Effects of Caffeine lntake and Stress on Sleep Quality in University Students (대학생의 카페인 섭취와 스트레스가 수면의 질에 미치는 영향)

  • Kim, Sang Hyeon;Gwon, Su A;Kwon, Yu Jin;Kim, Se In;Kim, Ye Jin;Oh, Hye Ran;Ha, Su Young;Cha, Nam Hyun
    • The Journal of the Convergence on Culture Technology
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    • v.8 no.5
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    • pp.161-169
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    • 2022
  • The purpose of this study performed to confirm the effect of caffeine intake and stress on sleep quality of college students. Research respondents and data collection were conducted on 269 college students through Google questionnaires from February 14 to March 13, 2022, and the research design is a descriptive survey study. Statistical analysis was performed using the SPSS 27.0 version as t-test and one way ANOVA. As a result of the study, it was found that most college students consume more caffeine than the average daily caffeine intake of Korean adults, although it is far below the recommended daily caffeine intake of Korean adults. The quality of sleep of college students is stress (r=.32, p=<).001) and caffeine intake (r=.204, p=.001). It was found that there was a positive correlation. Factors affecting sleep quality are body mass index (β=.1.19, p<.001) Stress (β=.3.37, p<.001), smoking (β=-.18, p=.001), caffeine intake (β=.15, p=.005) It was in order, and the explanatory power of the model was 24.8%.

BEEF MEAT TRACEABILITY. CAN NIRS COULD HELP\ulcorner

  • Cozzolino, D.
    • Proceedings of the Korean Society of Near Infrared Spectroscopy Conference
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    • 2001.06a
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    • pp.1246-1246
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    • 2001
  • The quality of meat is highly variable in many properties. This variability originates from both animal production and meat processing. At the pre-slaughter stage, animal factors such as breed, sex, age contribute to this variability. Environmental factors include feeding, rearing, transport and conditions just before slaughter (Hildrum et al., 1995). Meat can be presented in a variety of forms, each offering different opportunities for adulteration and contamination. This has imposed great pressure on the food manufacturing industry to guarantee the safety of meat. Tissue and muscle speciation of flesh foods, as well as speciation of animal derived by-products fed to all classes of domestic animals, are now perhaps the most important uncertainty which the food industry must resolve to allay consumer concern. Recently, there is a demand for rapid and low cost methods of direct quality measurements in both food and food ingredients (including high performance liquid chromatography (HPLC), thin layer chromatography (TLC), enzymatic and inmunological tests (e.g. ELISA test) and physical tests) to establish their authenticity and hence guarantee the quality of products manufactured for consumers (Holland et al., 1998). The use of Near Infrared Reflectance Spectroscopy (NIRS) for the rapid, precise and non-destructive analysis of a wide range of organic materials has been comprehensively documented (Osborne et at., 1993). Most of the established methods have involved the development of NIRS calibrations for the quantitative prediction of composition in meat (Ben-Gera and Norris, 1968; Lanza, 1983; Clark and Short, 1994). This was a rational strategy to pursue during the initial stages of its application, given the type of equipment available, the state of development of the emerging discipline of chemometrics and the overwhelming commercial interest in solving such problems (Downey, 1994). One of the advantages of NIRS technology is not only to assess chemical structures through the analysis of the molecular bonds in the near infrared spectrum, but also to build an optical model characteristic of the sample which behaves like the “finger print” of the sample. This opens the possibility of using spectra to determine complex attributes of organic structures, which are related to molecular chromophores, organoleptic scores and sensory characteristics (Hildrum et al., 1994, 1995; Park et al., 1998). In addition, the application of statistical packages like principal component or discriminant analysis provides the possibility to understand the optical properties of the sample and make a classification without the chemical information. The objectives of this present work were: (1) to examine two methods of sample presentation to the instrument (intact and minced) and (2) to explore the use of principal component analysis (PCA) and Soft Independent Modelling of class Analogy (SIMCA) to classify muscles by quality attributes. Seventy-eight (n: 78) beef muscles (m. longissimus dorsi) from Hereford breed of cattle were used. The samples were scanned in a NIRS monochromator instrument (NIR Systems 6500, Silver Spring, MD, USA) in reflectance mode (log 1/R). Both intact and minced presentation to the instrument were explored. Qualitative analysis of optical information through PCA and SIMCA analysis showed differences in muscles resulting from two different feeding systems.

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Association of Pre- and Perinatal Risk Factors With Tourette Syndrome or Chronic Tic Disorders in a Korean School-Age Population

  • Wooseok Choi;Soon-beom Hong;Johanna Inhynag Kim;Jung Lee;Soomin Jang;Yebin D Ahn;You Bin Lim;Sumin Kim;Mee Rim Oh;Bung-Nyun Kim
    • Journal of the Korean Academy of Child and Adolescent Psychiatry
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    • v.34 no.1
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    • pp.37-44
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    • 2023
  • Objectives: Tic disorders are highly heritable; however, growing evidence suggests that environmental factors play a significant role in their pathogenesis. Studies on these factors have been inconsistent, with conflicting results. Therefore, this study aimed to examine the associations of pre- and perinatal exposure to Tourette syndrome (TS) or chronic tic disorders (CTD) in Korean school-aged children. Methods: This case-control study used data from a large prospective cohort study. The primary outcome was TS/CTD diagnosis according to the Diagnostic and Statistical Manual of Mental Disorders, 5th edition (DSM-5) criteria and Kiddie-Schedule for Affective Disorders and Schizophrenia-Present and Lifetime Version-Korean Version. Demographic, pre-, and perinatal information was obtained from the maternal questionnaires. Data between the TS/CTD and control groups were compared using the chi-squared or Student's t-test, as appropriate. Two-step logistic regression analyses were used to test the association between TS/CTD and pre- and perinatal risk factors. Results: We included of 223 children (78 with TS/CTD and 145 controls). Significant differences in the demographic data between the two groups were observed. The male sex ratio, mean parental age, parental final education level, and family history of tics were included as confounders. In the final adjusted multivariable model, TS/CTD was significantly associated with antiemetic exposure during pregnancy (odds ratio [OR]=16.61, 95% confidence interval [CI] 1.49-185.22, p=0.02) and medically assisted reproduction (OR=7.89, 95% CI 2.28-27.28, p=0.01). Conclusion: Antiemetic exposure and medically assisted reproduction are significantly associated with the risk of TS/CTD. These results should be replicated in future prospective and gene-by-environment studies.

A comparison of synthetic data approaches using utility and disclosure risk measures (유용성과 노출 위험성 지표를 이용한 재현자료 기법 비교 연구)

  • Seongbin An;Trang Doan;Juhee Lee;Jiwoo Kim;Yong Jae Kim;Yunji Kim;Changwon Yoon;Sungkyu Jung;Dongha Kim;Sunghoon Kwon;Hang J Kim;Jeongyoun Ahn;Cheolwoo Park
    • The Korean Journal of Applied Statistics
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    • v.36 no.2
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    • pp.141-166
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    • 2023
  • This paper investigates synthetic data generation methods and their evaluation measures. There have been increasing demands for releasing various types of data to the public for different purposes. At the same time, there are also unavoidable concerns about leaking critical or sensitive information. Many synthetic data generation methods have been proposed over the years in order to address these concerns and implemented in some countries, including Korea. The current study aims to introduce and compare three representative synthetic data generation approaches: Sequential regression, nonparametric Bayesian multiple imputations, and deep generative models. Several evaluation metrics that measure the utility and disclosure risk of synthetic data are also reviewed. We provide empirical comparisons of the three synthetic data generation approaches with respect to various evaluation measures. The findings of this work will help practitioners to have a better understanding of the advantages and disadvantages of those synthetic data methods.

A Study on the Intention of Public Library Librarians to Use Artificial Intelligence-Based Technology (인공지능 기반 기술에 대한 공공도서관 사서의 사용의도 연구)

  • Gi Young Kim
    • Journal of the Korean Society for Library and Information Science
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    • v.57 no.3
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    • pp.163-190
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    • 2023
  • This study analyzed the effect of technology preparation and technology acceptance factors on the intention of public library librarians to use artificial intelligence-based technology using the technology acceptance model. To this end, a survey was conducted on public library librarians, and a total of 202 survey data were used for statistical analysis. As a result of the hypothesis test, first, optimism has a significant positive (+) effect on perceived usefulness, and discomfort has a significant negative (-) effect. Optimism and innovation on perceived ease of use were found to have a significant positive (+) effect, and discomfort was found to have a significant negative (-) effect. Second, perceived ease of use was found to have a significant positive (+) effect on perceived usefulness, and both perceived usefulness and perceived ease of use had a significant positive (+) effect on the intention to use. Third, optimism was found to have a significant positive (+) effect on the intention to use, and anxiety was found to have a significant negative (-) effect. This study is expected to provide basic data on the use of artificial intelligence technology in the future by empirically analyzing public library librarians' perceptions of artificial intelligence-based technology.

A study on the measurement and processing of medical service experience data - From the perspective of realizing patient-centeredness - (의료서비스 경험데이터의 측정 및 가공에 관한 연구 -환자중심성 실현 관점에서-)

  • Jinho, Ahn;Jungmin, Choi
    • Journal of Service Research and Studies
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    • v.13 no.3
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    • pp.147-159
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    • 2023
  • This study is a study to develop a model for measurement and processing of experience data, which is emerging as a core value in quality management of medical services. In the theoretical background, a literature study was conducted on the importance of experience in medical service, measurement and processing of experience data, and realization of patient-centeredness. Based on these literature and theoretical background research results, operational definitions were performed for the following four research variables, and statistical tests were conducted. Hypothesis 1 is the effect of measuring experience data from the perspective of three factors on persona modeling, Hypothesis 2 is the effect of persona modeling on service blueprint visualization, Hypothesis 3 is the effect of service blueprint visualization on realization of patient-centeredness, and Hypothesis 4 is persona modeling This is the effect that modeling has on the realization of patient-centeredness. After data-based testing of factor analysis, reliability analysis, and correlation analysis, all four hypotheses were adopted as a result of verification using regression analysis. In conclusion, in an era where it is difficult to recognize the value of having only good medical staff and medical equipment in hospitals, it was possible to grasp the meaning that what kind of medical service experience is continuously obtained is more important to patients than the effectiveness of medical staff and medical equipment. In the era of the service economy, the core of hospital service competitiveness is providing attractive experiences, which is the real strength of hospitals, so the measurement and processing of experience data, which is the subject of this study, will have an important meaning in realizing patient-centeredness and realizing smart hospitals.