• Communications for Statistical Applications and Methods
• /
• v.17 no.6
• /
• pp.899-907
• /
• 2010

Several non-response imputation methods are suggested, however, mainly cross-sectional imputations are studied and applied to this analysis. A simple and common imputation method for panel data is the cross-wave regression imputation or carry-over imputation as a special case of cross-wave regression imputation. This study suggests a multiple imputation method combined time series analysis and cross-sectional multiple imputation method. We compare this method and the cross-wave regression imputation method using MSE, MAE, and Bias. The 2008 monthly labor survey data is used for this study.

• Annals of Occupational and Environmental Medicine
• /
• v.35
• /
• pp.38.1-38.10
• /
• 2023

Background: Hearing loss (HL) is linked to an elevated risk of cardiovascular diseases (CVDs). The pathogeneses of HL and CVD commonly involve inflammatory responses. Previous studies investigated elevated levels of inflammatory biomarkers in subjects with HL, however, their findings did not demonstrate statistical significance. In our cross-sectional and longitudinal study, we investigated the correlation between HL and increased high-sensitivity C-reactive protein (hsCRP) levels to determine how HL is associated with CVDs. Methods: We conducted a cross-sectional study with workers aged over 18 years who underwent health check-ups at our institution between 2012 and 2018 (n = 566,507), followed by conducting a longitudinal study of workers aged > 18 who underwent health checkups at least twice at our institution between 2012 and 2018 (n = 173,794). The definition of HL was as an average threshold of ≥ 20 dB in pure-tone air conduction at 0.5, 1.0, and 2.0 kHz in both ears. The incidence of increased hsCRP levels throughout the follow-up period was defined as a level exceeding 3 mg/L. Logistic regression and generalized estimating equations were performed to estimate the risk of increased hsCRP levels according to the occurrence of HL in groups stratified by age. Results: In the cross-sectional study, the multivariate-adjusted odds ratio (OR) was 1.17 (95% confidence interval [CI]: 1.02-1.34); the OR was 0.99 (95% CI: 0.80-1.22) in those under 40 and 1.28 (1.08-1.53) in those over 40. In the longitudinal study, the multivariable-adjusted OR was 1.05 (95% CI: 0.92-1.19); the OR was 1.10 (95% CI: 0.90-1.35) in those under 40 and 1.20 (1.01-1.43) in those over 40. Conclusions: This cross-sectional and longitudinal study identified an association between HL and increased hsCRP levels in workers aged over 40 years.

• Architectural research
• /
• v.9 no.1
• /
• pp.31-37
• /
• 2007

This study presents the so-called Modified Allowable Stress Design (MASD) method for structural designs. The objective of this study is to qualitatively estimate uncertainties of tensile steel member's cross-sectional structural designs and find the optimal resulting design which can resist all uncertainty cases. The design parameters are assumed to be interval associated with lower and upper bounds and consequently interval methods are implemented to non-stochastically produce design results including the structural uncertainties. By seeking optimal uncertainty combinations among interval parameters, engineers can qualitatively describe uncertain design solutions which were not considered in conventional structural designs. Under the assumption that structures have basically uncertainties like displacement responses, the safety range of resulting designs is represented by lower and upper bounds depending on given tolerance error and structural parameters. As a numerical example uncertain cross-sectional areas of members that can resist applied loads are investigated and it demonstrates that the present design method is superior to conventional allowable stress designs (ASD) with respect to a reliably structural safety as well as an economical material.

• The Korean Journal of Pain
• /
• v.36 no.2
• /
• pp.230-241
• /
• 2023

Background: This study aimed to determine the prevalence of chronic pain and its contributing factors among teenagers aged 12-21 years in Shiraz, Iran. Methods: This cross-sectional study was conducted on adolescents aged 12-21 years. Demographic variables of the adolescents and their parents as well as the pain characteristics were assessed. Descriptive statistics, multinomial logistic regression, and regression models were used to describe the characteristics of the pain and its predictive factors. Results: The prevalence of chronic pain was 23.7%. The results revealed no significant difference between the male and female participants regarding the pain characteristics, except for the home medications used for pain relief. The results of a chi-square test showed that the mother's pain, education, and occupation, and the father's education were associated significantly with chronic pain in adolescents (P < 0.05). Multinomial logistic regression also showed the mother's history of pain played a significant role in the incidence of adolescents' chronic pain. Conclusions: The prevalence of chronic pain was relatively high in these adolescents. The results also provided basic and essential information about the contributing factors in this area. However, consideration of factors such as anxiety, depression, school problems, sleep, and physical activity are suggested in future longitudinal studies.

• Korean Journal of Child Studies
• /
• v.31 no.1
• /
• pp.1-17
• /
• 2010

This study explored the differences in gender, developmental period and parents in terms of parenting, the cross-sectional and longitudinal relationships in parenting by gender, and the cross-sectional and longitudinal relationships between participant roles in bullying situations and parenting by gender. The subjects were 498 4-5th grade children and the instruments utilized in this study were the Parental Bonding Instrument (Bowers, Smith, & Binney, 1994) and the Participant Roles Scale (Sutton & Smith, 1999). The subjects were contacted again one year after the first contact. Results showed that the relationships between parents were longitudinally quite stable. Girls whose fathers had higher levels of accurate monitoring were more likely to be defenders cross-sectionally. Girls whose parents had more accurate monitoring were less likely to be victims longitudinally. The results underscore the importance of examining both gender and participant roles in bullying situations.

• 한국전산유체공학회:학술대회논문집
• /
• 2008.03b
• /
• pp.61-64
• /
• 2008

The present study of these experiments are close examination of spray characteristics that are continuous liquid jet and modulated pressure pulse liquid jet. The experiments were conducted using water, over a range of cross-flow velocities from 42${\sim}$136 m/s, with injection frequencies of 35.7${\sim}$166.2 Hz. Between continuous cross-flow jet and pressure pulsed cross-flow jet for characteristics of penetration, breakup point, spray angle and macro spray shape are investigated experimentally. In cross-flow field, main parameter of liquid jet for breakup was cross-flow stream rather than pressure pulse frequency. As oscillation of the periodic pressure that could make liquid jet moved up and down, the mixing efficiency was increased. Also, a bulk of liquid jet puff was detected at upper field of liquid surface. So, this phenomenon has a good advantage of mixing spray from concentration of center area to outer area. Because of pressure pulsation frequency, an inclination of SMD for the structured layer was evanescent. Cross-sectional characteristics of SMD at downstream area were non-structured distributions. Then cross-sectional characteristics of SMD size were about same tendency over a range that is effect of spray mixing. The tendency of volume flux value for various frequency of pressure pulse was same distribution. And volume flux was decreased when the frequency of pressure pulse increase.

• Journal of Industrial Convergence
• /
• v.20 no.5
• /
• pp.21-28
• /
• 2022

Unlike previous studies, this study looked at the effect of the ideological tendencies of local government heads on the social welfare budget as a longitudinal study. This study was made possible by the election of the head of a progressive group in Gumi-si, a stronghold of conservatives, after the implementation of the local self-government system. Therefore, in this study, the change process of the political ideological orientation of Gumi-si's heads and the social welfare budget by year were listed and time-series analysis was conducted using actual cases of Gumi-si, Gyeongbuk for more than 12 years. As a result of the analysis, first, as in the cross-sectional analysis, in the longitudinal study, the change in the rate of increase in the social welfare budget according to the political ideological tendencies of the head of the local government showed a meaningful difference. Second, as in the previous cross-sectional analysis, the social welfare budget increased in the year before the election. Third, the same change in the growth rate as in the second did not appear at the end of the third elected term. All studies on the relationship between the political ideological tendencies of local government heads (including local councils) and the social welfare budget have been cross-sectional. However, this study has great implications in terms of the results of the first longitudinal cross-sectional analysis.

• Journal of Korean Neurosurgical Society
• /
• v.59 no.3
• /
• pp.276-281
• /
• 2016

Objective : Although trunk muscles in the lumbar spine preserve spinal stability and motility, little is known about the relationship between trunk muscles and spinal fusion rate. The aim of the present study is to evaluate the correlation between trunk muscles cross sectional area (MCSA) and fusion rate after posterior lumbar interbody fusion (PLIF) using stand-alone cages. Methods : A total of 89 adult patients with degenerative lumbar disease who were performed PLIF using stand-alone cages at L4-5 were included in this study. The cross-sectional area of the psoas major (PS), erector spinae (ES), and multifidus (MF) muscles were quantitatively evaluated by preoperative lumbar magnetic resonance imaging at the L3-4, L4-5, and L5-S1 segments, and bone union was evaluated by dynamic lumbar X-rays. Results : Of the 89 patients, 68 had bone union and 21 did not. The MCSAs at all segments in both groups were significantly different (p<0.05) for the PS muscle, those at L3-4 and L4-5 segments between groups were significantly different (p=0.048, 0.021) for the ES and MF muscles. In the multivariate analysis, differences in the PS MCSA at the L4-5 and L5-S1 segments remained significant (p=0.048, 0.043 and odds ratio=1.098, 1.169). In comparison analysis between male and female patients, most MCSAs of male patients were larger than female's. Fusion rates of male patients (80.7%) were higher than female's (68.8%), too. Conclusion : For PLIF surgery, PS muscle function appears to be an important factor for bone union and preventing back muscle injury is essential for better fusion rate.

• Fire Science and Engineering
• /
• v.30 no.3
• /
• pp.7-15
• /
• 2016

The cross-sectional shape factor is used worldwide to evaluate the scientific performance of fire-resistant structures. In South Korea, however, a system for applying a cross-sectional shape factor has not been arranged and circular or rectangular steel pipes are commonly used for large-scale steel frame buildings. On the other hand, coating material-spray steel beams and pillars that have received the certification of a fire-resistant structure from recognized organizations are mostly limited to a H-beam. A H-beam is granted a wide range of certifications without size limitations from a non-loading performance test with test standards based on the relevant provisions. Other types of steel pipe are to be certified for fireresistance according to shape. In this study, a cross-sectional shape factor was used to propose standard testing specifications for the application of coating material-sprayed circular and rectangular steel pipes, eventually to set the scope of certification for reasonable fire-resistant structures.

• Journal of Mechanical Science and Technology
• /
• v.14 no.3
• /
• pp.291-297
• /
• 2000

Modern helicopter rotor blades with non-homogeneous cross sections, composed of anisotropic material, require highly sophisticated structural analysis because of various cross sectional geometry and material properties. They may be subjected by the combined axial, bending, and torsional loading, and the dynamic and static behaviors of rotor blades are seriously influenced by the structural coupling under rotating condition. To simplify the analysis procedure using one dimensional beam model, it is necessary to determine the principal coordinate of the rotor blade. In this study, a method for the determination of the principal coordinate including elastic and shear centers is presented, based upon continuum mechanics. The scheme is verified by comparing the results with confirmed experimental results.