• Title/Summary/Keyword: Longitudinal Data Analysis

Search Result 837, Processing Time 0.028 seconds

Control Effectiveness Analysis of the hawkmoth Manduca sexta: a Multibody Dynamics Approach

  • Kim, Joong-Kwan;Han, Jae-Hung
    • International Journal of Aeronautical and Space Sciences
    • /
    • v.14 no.2
    • /
    • pp.152-161
    • /
    • 2013
  • This paper presents a control effectiveness analysis of the hawkmoth Manduca sexta. A multibody dynamic model of the insect that considers the time-varying inertia of two flapping wings is established, based on measurement data from the real hawkmoth. A six-degree-of-freedom (6-DOF) multibody flight dynamics simulation environment is used to analyze the effectiveness of the control variables defined in a wing kinematics function. The aerodynamics from complex wing flapping motions is estimated by a blade element approach, including translational and rotational force coefficients derived from relevant experimental studies. Control characteristics of flight dynamics with respect to the changes of three angular degrees of freedom (stroke positional, feathering, and deviation angle) of the wing kinematics are investigated. Results show that the symmetric (asymmetric) wing kinematics change of each wing only affects the longitudinal (lateral) flight forces and moments, which implies that the longitudinal and lateral flight controls are decoupled. However, there are coupling effects within each plane of motion. In the longitudinal plane, pitch and forward/backward motion controls are coupled; in the lateral plane, roll and side-translation motion controls are coupled.

Difference of Motivation of Move to Swedish Senior Cohousing by Longitudinal Analysis : Focus on Differences between the Years of 2001 and 2010 (스웨덴 노인용 코하우징 주민의 이주동기의 시계열적 차이 : 2001~2010년 10년간의 차이를 중심으로)

  • Choi, Jung Shin
    • Journal of Families and Better Life
    • /
    • v.31 no.3
    • /
    • pp.81-92
    • /
    • 2013
  • The purpose of this study is to identify difference in motivation of move to senior cohousing communities in Sweden during 10 years between the year of 2001 and 2010 by a longitudinal study. Questionnaire survey was used for the study. 313 data were collected from 12 senior cohousing communities, which were established by residents-initiated process. It includes 8 of Senior g${\aa}$rden cohousings in 2001 and 4 of +40 cohousings in 2010 nationwide in Sweden. The result indicates that there are significant differences in motivation of move to senior cohousing between 2001 and 2010. Comparing motivation of move to senior cohousing during 10 years, respondents of 2010 focus more on social merits than practical merits of cohousing as they move to cohousing communities. They stress more to the reasons as good contacts with neighbors, mutual supports, sharing common activities and getting rid of loneliness rather than burden of housing and garden management, and universal-designed house. The result of this study reveals motivation of move to senior cohousing has been changed during 10 years in Sweden.

Analysis on the Relation between Induced Longitudinal Voltage and Induced Noise Voltage caused by Electrified Railway system (고속전철시설에 의한 전력유도현상의 종전압과 잡음전압의 관계 분석)

  • Cho, Mun-Hwan;Lee, Snag-Mu;Cho, Pyung-Dong
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
    • /
    • 2011.10a
    • /
    • pp.589-592
    • /
    • 2011
  • Induced longitudinal voltage and induced noise voltage are used in the analysis on the power induction phenomenon and it is well known that these are in the subordinate relationship. But sometimes. there is a confusing situation that these voltages have not exact subordinate relationship in the actual measurement fields. So. we have analyze the correlation between induced longitudinal voltage and induced noise voltage by using tile actual measured data in the fields of 30 urban areas and 30 rural areas.

  • PDF

Bayesian estimation of median household income for small areas with some longitudinal pattern

  • Lee, Jayoun;Kim, Dal Ho
    • Journal of the Korean Data and Information Science Society
    • /
    • v.26 no.3
    • /
    • pp.755-762
    • /
    • 2015
  • One of the main objectives of the U.S. Census Bureau is the proper estimation of median household income for small areas. These estimates have an important role in the formulation of various governmental decisions and policies. Since direct survey estimates are available annually for each state or county, it is desirable to exploit the longitudinal trend in income observations in the estimation procedure. In this study, we consider Fay-Herriot type small area models which include time-specific random effect to accommodate any unspecified time varying income pattern. Analysis is carried out in a hierarchical Bayesian framework using Markov chain Monte Carlo methodology. We have evaluated our estimates by comparing those with the corresponding census estimates of 1999 using some commonly used comparison measures. It turns out that among three types of time-specific random effects the small area model with a time series random walk component provides estimates which are superior to both direct estimates and the Census Bureau estimates.

An Evaluation of Stress-Strain Behaviour of Earth-Rockfill Dam and Causes of Crack due to Water Table Fluctuation (수위변동에 따른 Earth-Rockfill 댐의 거동 및 균열원인에 대한 평가)

  • 김상규;한성길;이민형;안상로
    • Journal of the Korean Geotechnical Society
    • /
    • v.17 no.6
    • /
    • pp.149-162
    • /
    • 2001
  • Longitudinal cracks have occurred on the crest of dams soon after their construction of two earth-rocfill dams located in Samlangjin. They are a pair of pumped storage dams constructed for generation of electrical power. The upper dam and lower dam are subjected to the variation of water level more than 10m once in a day alteratively. This paper deals with the finding of possible causes for longitudinal cracks about upper dam. The dominant cause was considered to be due to fluctuation of water load, for which numerical analysis was carried out using the hyperbolic model. In order to obtain parameters necessary to the analysis, a series of triaxial tests was performed for both core and rock material. Also dynamic triaxial test was performed to obtain dynamic properties of soils, which could be used as input data to simulate frequent variation of stress change due to the water fluctuation. It was known from the numerical analysis that the confining pressure of upper 4m from the top of the crest become negative after repeating of water load, meaning that tension cracks occurred in the top portion of the crest. The depth of longitudinal cracks has been investigated by digging test pit on the crest. This results agree with the field observation.

  • PDF

Longitudinal Analysis on Success Factors of Smoking Cessation Using Panel Data (패널자료를 활용한 종단적 금연 성공요인 분석)

  • Song, Tae-Min;Lee, Ju-Yul
    • Korean Journal of Health Education and Promotion
    • /
    • v.26 no.3
    • /
    • pp.25-34
    • /
    • 2009
  • Objectives: This study has longitudinally analyzed male smokers in order to find out the trend rate of re-smoking after smoking cessation. Methods: The study was conducted with 800 male smokers who were provided with smoking cessation services for 3 years at public health centers from July 16, 2005 to July 15, 2008. Results: The results can be summarized as follows: First, the success rate of smoking cessation for at least 6 months during 3-year period was 54.4%. The failure rate of smoking cessation at the second year was 47.5% and the third 27.2%, which indicates that the failure rate diminishes as the period of smoking cessation extends. Second, the success rate of smoking cessation at the first trial was 35.0%, the second 24.3%, and the third 16.4%. The success rate diminished as the number of trial increased. Third, the continuation rate of smoking cessation for a year was 18.3%, for 2 years 13.4%. For the success group, the continuation rate of smoking cessation for a year was 52.5%, for 2 years 38.2%. For the failure group, the rate for a year was 21.5%. Fourth, in this longitudinal analysis, the most crucial variables that affect the success rate of smoking cessation are total number of consultation and the past experience of successful smoking cessation. Conclusion: This study shows that success of smoking cessation and the continuance of smoking cessation are both difficult, and that the past experience of smoking cessation plays an important role determining the present success of smoking cessation and continuance of smoking cessation. Thus, it is necessary to divide people into success group and failure group based on the results of the past experience of smoking cessation when they consult at smoking cessation clinics at public health centers. Further, in order to increase the continuation rate of smoking cessation, this study suggests that we need to consider ways to take care of those who successfully abstained from smoking for 6 months.

An Longitudinal Analysis of Changing Beliefs on the Use in IT Educatee by Elaboration Likelihood Model (정교화 가능성 모형에 의한 IT 피교육자 신용 믿음 변화의 종단분석)

  • Lee, Woong-Kyu
    • Asia pacific journal of information systems
    • /
    • v.18 no.3
    • /
    • pp.147-165
    • /
    • 2008
  • IT education can be summarized as persuading the educatee to accept IT. The persuasion is made by delivering the messages for how-to-use and where-to-use to the educatee, which leads formulation of a belief structure for using IT. Therefore, message based persuasion theory, as well as IT acceptance theories such as technology acceptance model(TAM), would play a very important role for explaining IT education. According to elaboration likelihood model(ELM) that has been considered as one of the most influential persuasion theories, people change attitude or perception by two routes, central route and peripheral route. In central route, people would think critically about issue-related arguments in an informational message. In peripheral route, subjects rely on cues regarding the target behavior with less cognitive efforts. Moreover, such persuasion process is not a one-shot program but continuous repetition with feedbacks, which leads to changing a belief structure for using IT. An educatee would get more knowledge and experiences of using IT as following an education program, and be more dependent on a central route than a peripheral route. Such change would reformulate a belief structure which is different from the intial one. The objectives of this study are the following two: First, an identification of the relationship between ELM and belief structures for using IT. Especially, we analyze the effects of message interpretation through both of central and peripheral routes on perceived usefulness which is an important explaining variable in TAM and perceived use control which have perceived ease of use and perceived controllability as sub-dimensions. Second, a longitudinal analysis of the above effects. In other words, change of the relationship between interpretation of message delivered by IT education and beliefs of IT using is analyzed longitudinally. For achievement of our objectives, we suggest a research model, which is constructed as three-layered. While first layer has a dependent variable, use intention, second one has perceived usefulness and perceived use control that has two sub-concepts, perceived ease of use and perceived controllability. Finally, third one is related with two routes in ELM, source credibility and argument quality which are operationalization of peripheral route and central route respectively. By these variables, we suggest five hypotheses. In addition to relationship among variables, we suggest two additional hypotheses, moderation effects of time in the relationships between perceived usefulness and two routes. That is, source credibility's influence on perceived usefulness is decreased as time flows, and argument quality's influence is increased. For validation of it, our research model is tested empirically. With measurements which have been validated in the other studies, we survey students in an Excel class two times for longitudinal analysis. Data Analysis is done by partial least square(PLS), which is known as an appropriate approach for multi-group comparison analysis with a small sized sample as like this study. In result. all hypotheses are statistically supported. One of theoretical contributions in this study is an analysis of IT education based on ELM and TAM which are considered as important theories in psychology and IS theories respectively. A longitudinal analysis by comparison between two surveys based on PLS is also considered as a methodological contribution. In practice, finding the importance of peripheral route in early stage of IT education should be notable.

Influential Factors of Social Relation on the Change in the Depression Level of Elderly -Longitudinal Analysis using a Latent Growth Model (노인의 사회적관계 요인이 우울 궤적에 미치는 영향 -잠재성장모형을 이용한 종단연구)

  • Kim, Jin-hun
    • The Journal of the Korea Contents Association
    • /
    • v.19 no.7
    • /
    • pp.138-148
    • /
    • 2019
  • Although social relation factors are confirmed to be closely associated with the depression level of the elderly through the preceding studies, there has been no specific study on subfactors of social relation that influence the trajectory of depression level. Considering such limitation, this study aims to analyze influencing subfactors of social relation on the trajectory of depression of the elderly. The 3rd, 4th, 5th, and 6th-year data of the Korean Longitudinal Survey of Ageing (KLoSA), which were provided by the Korea Employment Information Service (KEIS), were used in this study and 2,484 people aged 65 and over who responded to all the four-session surveys were used as final analysis subjects. In the result of the longitudinal study on depression level of the elderly aged 65 and over, the individual depression level was confirmed become lowered over time, showing a positive change. Also, the conditional model of Latent Growth Modeling (LGM) was applied to identify specific social network factors that influence the longitudinal change of depression level of the elderly. In the result of the analysis, it was found that initial value of depression of the elderly was influenced by whether they have a spouse or not, number of household member, meeting with close people, whether they do economic activity or not, whether they have a religion or not, etc. and the rate of change in depression of the elderly was influenced by number of household member, meeting with close people, expectation about life, etc. Through above results, this study suggests a need for specific programs and supports to continuously lower the depression level of the elderly.

Tumor Habitat Analysis Using Longitudinal Physiological MRI to Predict Tumor Recurrence After Stereotactic Radiosurgery for Brain Metastasis

  • Da Hyun Lee;Ji Eun Park;NakYoung Kim;Seo Young Park;Young-Hoon Kim;Young Hyun Cho;Jeong Hoon Kim;Ho Sung Kim
    • Korean Journal of Radiology
    • /
    • v.24 no.3
    • /
    • pp.235-246
    • /
    • 2023
  • Objective: It is difficult to predict the treatment response of tissue after stereotactic radiosurgery (SRS) because radiation necrosis (RN) and tumor recurrence can coexist. Our study aimed to predict tumor recurrence, including the recurrence site, after SRS of brain metastasis by performing a longitudinal tumor habitat analysis. Materials and Methods: Two consecutive multiparametric MRI examinations were performed for 83 adults (mean age, 59.0 years; range, 27-82 years; 44 male and 39 female) with 103 SRS-treated brain metastases. Tumor habitats based on contrast-enhanced T1- and T2-weighted images (structural habitats) and those based on the apparent diffusion coefficient (ADC) and cerebral blood volume (CBV) images (physiological habitats) were defined using k-means voxel-wise clustering. The reference standard was based on the pathology or Response Assessment in Neuro-Oncologycriteria for brain metastases (RANO-BM). The association between parameters of single-time or longitudinal tumor habitat and the time to recurrence and the site of recurrence were evaluated using the Cox proportional hazards regression analysis and Dice similarity coefficient, respectively. Results: The mean interval between the two MRI examinations was 99 days. The longitudinal analysis showed that an increase in the hypovascular cellular habitat (low ADC and low CBV) was associated with the risk of recurrence (hazard ratio [HR], 2.68; 95% confidence interval [CI], 1.46-4.91; P = 0.001). During the single-time analysis, a solid low-enhancing habitat (low T2 and low contrast-enhanced T1 signal) was associated with the risk of recurrence (HR, 1.54; 95% CI, 1.01-2.35; P = 0.045). A hypovascular cellular habitat was indicative of the future recurrence site (Dice similarity coefficient = 0.423). Conclusion: After SRS of brain metastases, an increased hypovascular cellular habitat observed using a longitudinal MRI analysis was associated with the risk of recurrence (i.e., treatment resistance) and was indicative of recurrence site. A tumor habitat analysis may help guide future treatments for patients with brain metastases.

The Effects of Regional Branding on Soybean Products: Evidence from Consumer Longitudinal Data in Korea (두류식품의 지역 이름 브랜드화의 효과: 한국 소비자의 종적 데이터 분석을 중심으로)

  • Kim, Tae-Kyung;Jung, Gu-Hyun
    • Journal of Distribution Science
    • /
    • v.14 no.10
    • /
    • pp.109-116
    • /
    • 2016
  • Purpose - This study investigates the purchase pattern relating to soybean products in Korea. Specifically, the effect of branding based on a regional name was analyzed in terms of consumer purchase frequencies. The primary purpose of this study is to understand why family characteristics affect product selection for a regional brand in the soybean food category. Research design, data, and methodology - We used data collected by the Rural Development Administration (RDA) of Korea. The RDA has monitored agricultural food consumers for years in order to obtain purchase records. Panel participants live in regions near the capital city of Seoul, Korea. Examining data from January 2010 to May 2016, 667 families were selected for analysis. The final data set was 1,335,402. Each purchase item by each individual family was aggregated to a countable weekly observation. To analyze the data set quantitatively, zero-inflation regression was adopted, which was appropriate to avoid biases from overly dispersed observations. Results - We hypothesized the effects of regional branding from the viewpoint of the family characteristics. The first hypothesis was that the number of children would be positively associated with the purchase of a regional brand of soybean products. The result strongly supported this hypothesis. The second hypothesis was that the number of family members would be negatively associated with the purchase of the soybean products of a regional brand. Based on empirical analysis, we concluded that this hypothesis was partially supported. The third hypothesis was the presence of an interaction effect between the number of children and the family size, which was supported by the results. As a supplementary analysis, we also tested mean-variance differences in terms of categories and regional branding with corporate branding. Conclusion - The results of this study provide insights for regional branding strategies in agricultural food management. This study appears to be one of the seminal studies trying to analyze purchase patterns from longitudinal observations. In addition, this study adopted variables characterizing family lifestyle. This study confirmed that children and family size should be considered when soybean product brands are introduced.