• Atmosphere
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• v.20 no.3
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• pp.287-306
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• 2010

An ensemble Kalman filter (EnKF) with Weather Research and Forecasting (WRF) Model is applied for Typhoon Wukong (200610) to investigate the performance of ensemble forecasts depending on experimental configurations of the EnKF. In addition, the ensemble sensitivity analysis is applied to the forecast and analysis ensembles generated in EnKF, to investigate the possibility of using the ensemble sensitivity analysis as the adaptive observation guidance. Various experimental configurations are tested by changing model error, ensemble size, assimilation time window, covariance relaxation, and covariance localization in EnKF. First of all, experiments using different physical parameterization scheme for each ensemble member show less root mean square error compared to those using single physics for all the forecast ensemble members, which implies that considering the model error is beneficial to get better forecasts. A larger number of ensembles are also beneficial than a smaller number of ensembles. For the assimilation time window, the experiment using less frequent window shows better results than that using more frequent window, which is associated with the availability of observational data in this study. Therefore, incorporating model error, larger ensemble size, and less frequent assimilation window into the EnKF is beneficial to get better prediction of Typhoon Wukong (200610). The covariance relaxation and localization are relatively less beneficial to the forecasts compared to those factors mentioned above. The ensemble sensitivity analysis shows that the sensitive regions for adaptive observations can be determined by the sensitivity of the forecast measure of interest to the initial ensembles. In addition, the sensitivities calculated by the ensemble sensitivity analysis can be explained by dynamical relationships established among wind, temperature, and pressure.

• Asian Spine Journal
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• v.12 no.6
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• pp.1100-1105
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• 2018

Study Design: Prospective observational study. Purpose: To determine the incidence of postoperative urinary retention (POUR) in patients undergoing elective posterior lumbar spine surgery and identify the risk factors associated with the development of POUR. Overview of Literature: POUR following surgery can lead to detrusor dysfunction, urinary tract infections, prolonged hospital stay, and a higher treatment cost; however, the risk factors for POUR in spine surgery remain unclear. Methods: A prospective, consecutive analysis was conducted on patients undergoing elective posterior lumbar surgery in the form of lumbar discectomy, lumbar decompression, and single-level lumbar fusions during a 6-month period. Patients with spine trauma, preoperative neurological deficit, previous urinary disturbance/symptoms, multiple-level fusion, and preoperative catheterization were excluded from the study. Potential patient- and surgery-dependent risk factors for the development of POUR were assessed. Univariate analysis and a multiple logistical regression analysis were performed. Results: A total of 687 patients underwent posterior lumbar spine surgery during the study period; among these, 370 patients were included in the final analysis. Sixty-one patients developed POUR, with an incidence of 16.48%. Significant risk factors for POUR were older age, higher body mass index (BMI), surgery duration, intraoperative fluid administration, lumbar fusion versus discectomy/decompression, and higher postoperative pain scores (p<0.05 for all). Sex, diabetes, and the type of inhalational agent used during anesthesia were not significantly associated with POUR. Multiple logistical regression analysis, including age, BMI, surgery duration, intraoperative fluid administration, fusion surgery, and postoperative pain scores demonstrated a predictive value of 92% for the study population and 97% for the POUR group. Conclusions: POUR was associated with older age, higher BMI, longer surgery duration, a larger volume of intraoperative fluid administration, and higher postoperative pain scores. The contribution of postoperative pain scores in the multiple regression analysis was a significant predictor of POUR.

• Korean Circulation Journal
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• v.53 no.10
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• pp.710-719
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• 2023

Background and Objectives: In previous studies, high homocysteine levels were associated with high cardiovascular mortality. However, these results were inconsistent with those of randomized controlled trials. We aimed to evaluate the causal role of homocysteine on allcause and cardiovascular mortality using Mendelian randomization (MR) analysis. Methods: This study included the 10,005 participants in the Namwon Study. In conventional observational analysis, age, sex, survey years, lifestyles, body mass index, comorbidities, and serum folate level were adjusted using multivariate Cox proportional regression. MR using 2-stage least squares regression was used to evaluate the association between genetically predicted plasma homocysteine levels and mortality. Age, sex, and survey years were adjusted for each stage. The methylenetetrahydrofolate reductase (MTHFR) polymorphism was used as an instrumental variable for predicting plasma homocysteine levels. Results: Observed homocysteine levels were positively associated with all-cause (hazard ratio [HR], 1.40; 95% confidence interval [CI], 1.26-1.54) and cardiovascular (HR, 1.62; 95% CI, 1.28-2.06) mortality when plasma homocysteine levels doubled. However, these associations were not significant in MR analysis. The HRs of doubling genetically predicted plasma homocysteine levels for all-cause and cardiovascular mortality were 0.99 (95% CI, 0.62-1.57) and 1.76 (95% CI, 0.54-5.77), respectively. Conclusions: This MR analysis did not support a causal role for elevated plasma homocysteine concentrations in premature deaths.

• Journal of Korean Academy of Nursing
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• v.52 no.5
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• pp.479-498
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• 2022

Purpose: This study aimed to examine effect sizes of leadership styles of nursing managers on turnover intention of hospital nurses. Methods: A systematic review and meta-analysis were conducted in accordance with the PRISMA and MOOSE guidelines. Participants were nurses working in hospitals. The intervention involved nursing managers' leadership styles; the outcome assessed was nurses' turnover intention. This was an observational study design. Eleven databases were searched to obtain articles published in Korean or English. Of the 14,428 articles reviewed, 21 were included in systematic review and meta-analysis. Comprehensive Meta-Analysis and R software programs were used. Results: The total effect size r (ESr) was - 0.25 (95% confidence interval: - 0.29 to - 0.20). Effect sizes of each leadership style on turnover intention were as follows: ethical leadership (ESr = - 0.34), transformational leadership (ESr = - 0.28), authentic leadership (ESr = - 0.23), transactional leadership (ESr = - 0.21), and passive avoidant leadership (ESr = 0.13). Ethical leadership was the most effective style in decreasing turnover intention of hospital nurses. Conclusion: Positive leadership styles of nurse managers effectively decrease turnover intention of hospital nurses, and negative leadership styles of nurse managers effectively increase turnover intention of hospital nurses. The ethical leadership style is the most effective in decreasing turnover intention of hospital nurses; however, it requires careful interpretation as its effects are reported by only two studies. This study contributes to addressing the high turnover rate of hospital nurses and developing positive leadership styles of nurse managers in hospital settings.

• Journal of Medicine and Life Science
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• v.19 no.3
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• pp.109-115
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• 2022

During emergencies, the time from symptom onset to definitive treatment determines the final outcome. Therefore, the emergency medical service (EMS) system in Korea, aims to transfer patients requiring emergency care to appropriate medical facilities within 30 minutes. This is in an attempt to improve the chances of survival and reduce sequelae. We attempted to locate areas vulnerable to prehospital transportation and identify hot spots with high demand for emergency medical helicopters in Jeju, by using a grid-based geospatial analysis. This retrospective cross-sectional observational study employed EMS data of 119 ambulance run sheets spanning from January 1, 2010 to September 30, 2018 in Jeju. The location data of emergency patients was superimposed on the spatial analysis frame using the geographic information system (GIS). Subsequently, the locations of long-distance transfer and delayed transfers to the hospital were analyzed, to identify hot spots where the demand for helicopter emergency services would be high. Of the total analysis targets, 42.2% (20,288 people) took more than 30 minutes from reporting to 119 dispatchers to hospital transfer. As the transfer time interval increased, the patient occurrence time increased in the city of Jeju, increased in Seogwipo, and the ratio of patients/guardians to select a transfer hospital rose with significant differences. This study identified the characteristics related to time delays in prehospital transfer of emergency patients in Jeju, and the areas vulnerable to prehospital emergency care were derived and visualized through spatial analysis using the GIS.

• The Bulletin of The Korean Astronomical Society
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• v.40 no.1
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• pp.60.1-60.1
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• 2015

High energy photons and mechanical energy produced by the process of star formation result in copious FIR molecular and atomic lines, which are important coolants of the system. Photons thermally or mechanically induced could dissociate water in the dense envelope to change relative abundances among the species of O, OH, and H2O. Here we analyze OH emission lines toward embedded young stellar objects (YSOs) observed as part of the Herschel open time key program, 'Dust, Ice, and Gas In Time (DIGIT)' in order to study the physical conditions of associated gas and the energy budget loaded on the OH line emission. According to our analysis of the Herschel/PACS spectra, OH emission peaks at the central spaxel in most of sources, but several sources show spatially extended emission structures. In the extended emission sources, the distribution of OH emission is correlated with that of [OI] emission and extended along the outflow directions. Considering the diversity of source properties, ratios between detected OH lines are relatively constant among sources. In addition, each OH line has strong correlation with bolometric luminosity. In order to determine the physical conditions of YSOs, we adopt several methods for the analysis of the OH lines: rotational diagram, non-LTE LVG analysis, and a 2-D PDR code. From the simple LVG analysis, we find that the thermal solution with the dense ( > $10^7cm^{-3}$) and warm ( ~ 100 K) OH gas reproduces the ratios of detected OH lines. However, our self-consistent PDR 2-D model, which can deal with the IR-pumping effect from the central protostar as well as the warm dust in situ, cannot fit the observational results, suggesting that an irradiated shock model is necessary for a better interpretation.

• Toxicological Research
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• v.28 no.2
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• pp.81-91
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• 2012

Many risk factors exist for chemotherapy-induced nausea and vomiting (CINV). This study utilized a multivariate projection technique to identify which risk factors were predictive of CINV in clinical practice. A single-centre, prospective, observational study was conducted from January 2007~July 2010 in Singapore. Patients were on highly (HECs) and moderately emetogenic chemotherapies with/without radiotherapy. Patient demographics and CINV risk factors were documented. Daily recording of CINV events was done using a standardized diary. Principal component (PC) analysis was performed to identify which risk factors could differentiate patients with and without CINV. A total of 710 patients were recruited. Majority were females (67%) and Chinese (84%). Five risk factors were potential CINV predictors: histories of alcohol drinking, chemotherapy-induced nausea, chemotherapy-induced vomiting, fatigue and gender. Period (ex-/current drinkers) and frequency of drinking (social/chronic drinkers) differentiated the CINV endpoints in patients on HECs and anthracycline-based, and XELOX regimens, respectively. Fatigue interference and severity were predictive of CINV in anthracycline-based populations, while the former was predictive in HEC and XELOX populations. PC analysis is a potential technique in analyzing clinical population data, and can provide clinicians with an insight as to what predictors to look out for in the clinical assessment of CINV. We hope that our results will increase the awareness among clinician-scientists regarding the usefulness of this technique in the analysis of clinical data, so that appropriate preventive measures can be taken to improve patients' quality of life.

• Journal of Korea Multimedia Society
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• v.12 no.11
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• pp.1652-1660
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• 2009

The main objective of this research is to build a behavior prediction model of gameplay for MMO (Massively Multiplayer Online) game using the GOMS analysis method. GOMS analysis is an observational approach to HCI(Human Computer Interaction) to model and predict behaviors of a human operator in a highly interactive task. In this research, a pilot experiment was previously conducted with three skilled gamers. The gamers were provided with the goals and operators through the user's guide book, and they found methods and selection rules while being observed. Based on the results obtained from the pilot study, this research was expanded and the model was further tested with 30 subjects (game experts). The new outcomes revealed that the relevance of GOMS analysis for predicting selection rules is 96.25% according to the degree of abstraction and 77.35% based on the degree of complexity. This research will provide game designers with a new testing mechanism in the early development stages, in order to improve the quality of the game product.

• Publications of The Korean Astronomical Society
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• v.26 no.3
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• pp.89-101
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• 2011

The International Olympiad on Astronomy and Astrophysics (IOAA) initiated by the Thailand Astronomical Society in 2007 is an annual competition for high school students. One of its aim is to enhance the development of international exchange in the field of school education in astronomy and astrophysics. This paper first provides the overview of the IOAA in terms of key regulations based on its statutes, history and current status. Secondly, the published syllabus of the IOAA is used for content analysis according to subject areas regarding the exam questions of the IOAA in theoretical, observational and data analysis parts from 2007 to 2010. Also, a scientific inquiry framework is applied to the same questions for assessment based on scientific inquiry in the cognitive aspect with two sub-classes of scientific knowledge and scientific reasoning. Among a dozen astronomy subject areas listed on the syllabus, the theoretical part of the IOAA makes more frequent use of the Sun, the solar system, properties of stars, and concept of time. In content knowledge, a factor of scientific knowledge, the IOAA questions, especially in the theoretical part have a lesser degree in difficulty than the IAO (International Astronomy Olympiad) exam questions for the same period whose degree in difficulty is comparable to college level. With regard to scientific reasoning, the IOAA questions tend to involve convergent rather than divergent thinking. Lastly, in light of these findings, discussions are given on the outcome of Korean participation in the previous IOAAs and ways to help better in preparing Korean students for future astronomy Olympiads.

• Journal of Preventive Medicine and Public Health
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• v.49 no.6
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• pp.367-375
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• 2016

Objectives: The established theory that breast density is an independent predictor of breast cancer risk is based on studies targeting white women in the West. More Asian women than Western women have dense breasts, but the incidence of breast cancer is lower among Asian women. This meta-analysis investigated the association between breast density in mammography and breast cancer risk in Asian women. Methods: PubMed and Scopus were searched, and the final date of publication was set as December 31, 2015. The effect size in each article was calculated using the interval-collapse method. Summary effect sizes (sESs) and 95% confidence intervals (CIs) were calculated by conducting a meta-analysis applying a random effect model. To investigate the dose-response relationship, random effect dose-response meta-regression (RE-DRMR) was conducted. Results: Six analytical epidemiology studies in total were selected, including one cohort study and five case-control studies. A total of 17 datasets were constructed by type of breast density index and menopausal status. In analyzing the subgroups of premenopausal vs. postmenopausal women, the percent density (PD) index was confirmed to be associated with a significantly elevated risk for breast cancer (sES, 2.21; 95% CI, 1.52 to 3.21; $I^2=50.0%$). The RE-DRMR results showed that the risk of breast cancer increased 1.73 times for each 25% increase in PD in postmenopausal women (95% CI, 1.20 to 2.47). Conclusions: In Asian women, breast cancer risk increased with breast density measured using the PD index, regardless of menopausal status. We propose the further development of a breast cancer risk prediction model based on the application of PD in Asian women.