https://scholar.korea.ac.kr/handle/2021.sw.korea/2853 2026-04-05T16:15:17Z 2026-04-05T16:15:17Z Ren, Dianxu Kwon, Amy M. https://scholar.korea.ac.kr/handle/2021.sw.korea/128276 2024-11-15T06:35:08Z 2021-04-01T00:00:00Z

Title: Effect of walking behavior on perceived stress based on binary multi-level modeling Authors: Ren, Dianxu; Kwon, Amy M. Abstract: Aim Present study examines whether perceived stress levels of health controls may be reduced by walking behavior in daily life. Subject and methods The subjects were a part of the Korean National Health and Nutritional Examination Survey (KNHANES), an ongoing nationwide epidemiology study, in 2008 and 2011. We examined the association between walking behavior and perceived stress (PS) of healthy controls based on multi-level modeling. We assumed that walking behavior may have an influence on how people perceive their stress, and observed the significance of the effect with adjustment for other covariates. Results We found that the odds of 'high PS' are about 16% lower for those with walking behavior with adjustment for other covariates. Inj addition, the odds of 'high PS' were lower for male subjects than female subjects by about 19%, while current smokers showed 1.2 times higher odds of 'high PS'. Based on our final model, there was significant interaction effect between age and sleep duration. In particular, sleep duration has a role in reducing the odds of 'high PS' by 18% at the reference age of 52.98 years. Conclusion Walking behavior has the potential to reduce perceived stress in daily life. Also, there are strong associations between smoking, sleep duration, and perceived stress.

2021-04-01T00:00:00Z Kwon, Amy M. https://scholar.korea.ac.kr/handle/2021.sw.korea/75473 2024-11-15T03:24:15Z 2018-05-31T00:00:00Z

Title: A rank weighted classification for plasma proteomic profiles based on case-based reasoning Authors: Kwon, Amy M. Abstract: Background: It is a challenge to precisely classify plasma proteomic profiles into their clinical status based solely on their patterns even though distinct patterns of plasma proteomic profiles are regarded as potential to be a biomarker because the profiles have large within-subject variances. Methods: The present study proposes a rank-based weighted CBR classifier (RWCBR). We hypothesized that a CBR classifier is advantageous when individual patterns are specific and do not follow the general patterns like proteomic profiles, and robust feature weights can enhance the performance of the CBR classifier. To validate RWCBR, we conducted numerical experiments, which predict the clinical status of the 70 subjects using plasma proteomic profiles by comparing the performances to previous approaches. Results: According to the numerical experiment, SVM maintained the highest minimum values of Precision and Recall, but RWCBR showed highest average value in all information indices, and it maintained the smallest standard deviation in F-1 score and G-measure. Conclusions: RWCBR approach showed potential as a robust classifier in predicting the clinical status of the subjects for plasma proteomic profiles.

2018-05-31T00:00:00Z Liu, Wei-Chiang Choi, Gun Lee, Sang-Ho Kwon, Amy M. Kim, K. Hwan Park, Jeeyoung Park, Hyeon Seon https://scholar.korea.ac.kr/handle/2021.sw.korea/76880 2024-11-15T21:41:33Z 2018-03-01T00:00:00Z

Title: Epidural Fluid Collection After Percutaneous Endoscopic Lumbar Discectomy Authors: Liu, Wei-Chiang; Choi, Gun; Lee, Sang-Ho; Kwon, Amy M.; Kim, K. Hwan; Park, Jeeyoung; Park, Hyeon Seon Abstract: OBJECTIVE: The frequency and extent of epidural fluid collection after percutaneous endoscopic lumbar discectomy (PELD) have not been previously described. The purpose of this study was to evaluate the significance of epidural fluid collection after PELD. METHODS: From March 2008 to November 2015, immediate postoperative magnetic resonance imaging (MRI) of 464 consecutive patients, comprising 284 men and 180 women, were obtained after PELD. The mean age of the patients at the time of admission was 43.1 years (range, 18-81 years). We also performed 24-hour follow-up MRIs after PELD in 35 patients to evaluate the morphologic changes on epidural fluid collection and to identify whether the collection was due to saline accumulation or cerebrospinal fluid leak. RESULTS: The level of disc herniation was at L4-5, L5-S1, L3-4, and L2-3 in 245 (52.8%), 173 (37.3%), 37 (8.0%), and 9 (1.9%) patients, respectively. Of 464 patients, 418 (90.1%) had abnormal epidural fluid collection, 404 (87.1%) patients had ventral epidural fluid collection, 393 (84.7%) patients had dorsal epidural fluid collection, and 10 patients had epidural hematoma as per immediate postoperative MRI. According to the 24-hour follow-up MRI findings, 30 patients had epidural fluid collection; the epidural fluid collection in 28 patients (93.3%) resolved with time, and a minimal amount of fluid remained in 2 patients, but the lesion size decreased compared with that on the previous day. CONCLUSIONS: Epidural fluid collection usually occurs after percutaneous endoscopic discectomy, which is mainly due to saline accumulation and typically resolves with time, without treatment or complications.

2018-03-01T00:00:00Z Kwon, Amy M. Tang, Gong https://scholar.korea.ac.kr/handle/2021.sw.korea/86326 2024-11-15T04:56:10Z 2017-01-01T00:00:00Z

Title: Application of an imputation method for variance estimation under pseudo-likelihood when missing data are NMAR Authors: Kwon, Amy M.; Tang, Gong Abstract: When data are outcome-dependent non response, pseudo-likelihood yields consistent regression coefficients without specifying the missing data mechanism. However, it is onerous to derive parameter estimators including their standard errors from the regression coefficients under pseudo-likelihood (PL). The present study applies an imputation method to compute the asymptotic standard errors of parameter estimators. The proposed method is simpler than Delta method and it showed similar effect size of the standard errors to bootstrapping in simulation and application studies.

2017-01-01T00:00:00Z