• Journal of Korean Neurosurgical Society
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• 제50권4호
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• pp.293-298
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• 2011

Objective : The extracellular matrix (ECM) and cell adhesion molecules play crucial roles in angiogenesis, apoptosis, thrombosis, and inflammation, and also contribute to the pathogenesis of stroke. Integrin, alpha 6 (ITGA6) is a member of ECM adhesion receptors. We investigated whether two single nucleotide polymorphisms (SNPs) (rs11895564, Ala380Thr; rs2293649, Asp694Asp) of ITGA6 were associated with the development and clinical phenotypes of intracerebral hemorrhage (ICH) and ischemic stroke (IS). Methods : We enrolled 199 stroke (78 ICH and 121 IS) and 291 control subjects. Stroke patients were divided into subgroups according to the scores of the National Institutes of Health Stroke Survey (NIHSS, <6 and ${\geq}6$) and Modified Barthel Index (MBI, <60 and ${\geq}60$). SNPStats, SNPAnalyzer, and Helixtree programs were used to calculate odds ratios, 95% confidence intervals, and p values. Multiple logistic regression models were used to analyze genetic data. Results : A missense SNP rs11895564 was associated with the development of ICH (p=0.026 in codominant2, p=0.013 in recessive, p=0.02 in log-additive models; p=0.041 in allele distributions). The A allele frequency of rs11895564 was higher in the ICH group (13.5%) than in the control group (8.1%). In the clinical phenotypes, rs11895564 and rs2293649 showed significant associations in the MBI scores of IS (p=0.014 in codominant1 model; p=0.02 in allele distributions) and NIHSS scores of ICH (p=0.017 in codominant2, p=0.035 in recessive, p=0.035 in log-additive models), respectively. Conclusion : These results suggest that ITGA6 may be associated with the development and clinical phenotypes of stroke in Korean population.

• Journal of Preventive Medicine and Public Health
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• 제56권6호
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• pp.515-522
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• 2023

Objectives: The pandemic caused by coronavirus disease 2019 (COVID-19) has exerted an unprecedented impact on the health of populations worldwide. However, the adverse health consequences of the pandemic in terms of infection and mortality rates have varied across countries. In this study, we investigate whether COVID-19 mortality rates across a group of developed nations are associated with characteristics of their healthcare systems, beyond the differential policy responses in those countries. Methods: To achieve the study objective, we distinguished healthcare systems based on the extent of healthcare decommodification. Using available daily data from 2020, 2021, and 2022, we applied quantile regression with non-additive fixed effects to estimate mortality rates across quantiles. Our analysis began prior to vaccine development (in 2020) and continued after the vaccines were introduced (throughout 2021 and part of 2022). Results: The findings indicate that higher testing rates, coupled with more stringent containment and public health measures, had a significant negative impact on the death rate in both pre-vaccination and post-vaccination models. The data from the post-vaccination model demonstrate that higher vaccination rates were associated with significant decreases in fatalities. Additionally, our research indicates that countries with healthcare systems characterized by high and medium levels of decommodification experienced lower mortality rates than those with healthcare systems involving low decommodification. Conclusions: The results of this study indicate that stronger public health infrastructure and more inclusive social protections have mitigated the severity of the pandemic's adverse health impacts, more so than emergency containment measures and social restrictions.

• 응용통계연구
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• 제19권2호
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• pp.305-317
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• 2006

시계열 자료에서의 특이치, 특히 이 가운데 가법적 특이치가 모형의 식별, 모수의 추정 및 예측과 관련된 분석 전과정을 왜곡하는 것은 잘 알려져 있다. 그러나 특이치가 다수 발생하는 경우, 특히 연속적으로 집단을 이루어 발생할 때 대부분 특이치 검출방법은 가면화효과와 수렁화효과때문에 이들을 정확히 판별하지 못한다. 본 논문에서는 p차 자기상관회귀모형에 대한 고붕괴점 회귀추정량을 이용한 양방향 로버스트 필터방법을 제안했다. 실제 사례와 모의실험을 통해 제안한 방법이 매우 정확하게 시계열 자료에 포함된 특이치들을 검출하고 있음을 확인할 수 있다.

• Asian-Australasian Journal of Animal Sciences
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• 제28권10호
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• pp.1407-1418
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• 2015

A total of 32,817 test-day milk yield (TDMY) records of the first lactation of 4,056 Girolando cows daughters of 276 sires, collected from 118 herds between 2000 and 2011 were utilized to estimate the genetic parameters for TDMY via random regression models (RRM) using Legendre's polynomial functions whose orders varied from 3 to 5. In addition, nine measures of persistency in milk yield ($PS_i$) and the genetic trend of 305-day milk yield (305MY) were evaluated. The fit quality criteria used indicated RRM employing the Legendre's polynomial of orders 3 and 5 for fitting the genetic additive and permanent environment effects, respectively, as the best model. The heritability and genetic correlation for TDMY throughout the lactation, obtained with the best model, varied from 0.18 to 0.23 and from -0.03 to 1.00, respectively. The heritability and genetic correlation for persistency and 305MY varied from 0.10 to 0.33 and from -0.98 to 1.00, respectively. The use of $PS_7$ would be the most suitable option for the evaluation of Girolando cattle. The estimated breeding values for 305MY of sires and cows showed significant and positive genetic trends. Thus, the use of selection indices would be indicated in the genetic evaluation of Girolando cattle for both traits.

• Journal of Preventive Medicine and Public Health
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• 제37권4호
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• pp.300-305
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• 2004

Objectives : The exposure to particulate air pollution during the pregnancy has reported to result in adverse pregnancy outcome such as low birth weight, preterm birth, still birth, and intrauterine growth retardation (IUGR). We aim to assess whether prenatal exposure of particulate matter less than 10 (m in diameter ($PM_{10}$) is associated with preterm birth in Seoul, South Korea. Methods : We included 382,100 women who delivered a singleton at 25-42 weeks of gestation between 1998 and 2000. We calculated the average PM10 exposures for each trimester period and month of pregnancy, from the first to the ninth months, based on the birth date and gestational age. We used three different models to evaluate the effect of air pollution on preterm birth; the logistic regression model, the generalized additive logistic regression model, and the proportional hazard model. Results : The monthly analysis using logistic regression model suggested that the risks of preterm birth increase with PM10 exposure between the sixth and ninth months of pregnancy and the highest risk was observed in the seventh month (adjusted odds ratio=1.07, 95% CI=1.01-1.14). We also found the similar results using generalized additive model. In the proportional hazard model, the adjusted odds ratio for preterm births due to PM10 exposure of third trimester was 1.04 (95% CI=0.96-1.13) and PM10 exposure between the seventh month and ninth months of pregnancy was associated with the preterm births. Conclusions : We found that there were consistent results when we applied the three different models. These findings suggest that air pollution exposure during the third trimester pregnancy has an adverse effect on preterm birth in South Korea.

• 생물정신의학
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• 제26권2호
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• pp.88-93
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• 2019

Objectives Psychological stress has been known to increase the risk of schizophrenia. Because stress responses are mainly mediated by cortisol, the action of the glucocorticoid receptors (Nuclear Receptor Subfamily 3 Group C Member 1, NR3C1) is possibly related to the pathogenesis of schizophrenia. In this study, we investigated the associations between polymorphisms of NR3C1 and schizophrenia. Methods Four single nucleotide polymorphisms (SNPs) (rs17100236, rs2963155, rs9324924, and rs7701443) of NR3C1 were genotyped in 208 patients with schizophrenia and 339 healthy individuals. A chi-square test was performed to test differences in allele distributions among groups. A multiple logistic regression model was used to calculate odds ratios (ORs) and 95% confidence intervals (CIs), and multiple inheritance models to analyze the associations between schizophrenia and SNPs (the dominant, recessive and additive models). Results The minor allele frequencies of two SNPs were significantly higher in the schizophrenia group than in those of the control group (rs2963155 G > A : 0.25 vs. 0.18, p = 0.0066 ; rs7701443 A > G : 0.40 vs. 0.33, p = 0.012). The genotype frequencies of two SNPs were found to be significantly different between patients with schizophrenia and controls in the dominant model (rs2963155 : AG/GG vs. AA, OR = 1.66, 95% CI = 1.16-2.38, p = 0.0055, rs7701443 : AG/AA vs. GG, OR = 1.61, 95% CI = 1.11-2.34, p = 0.01) and the log-additive model (rs2963155 : AG vs. GG vs. AA, OR = 1.54, 95% CI = 1.13-2.10, p = 0.0067). Conclusions This study showed significant associations between NR3C1 polymorphisms and schizophrenia. It suggests that NR3C1 may play a role in the pathogenesis of schizophrenia.

• Asian-Australasian Journal of Animal Sciences
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• 제31권10호
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• pp.1542-1549
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• 2018

Objective: Because lactation periods in dairy cows lengthen with increasing total milk production, it is important to predict individual productivities after 305 days in milk (DIM) to determine the optimal lactation period. We therefore examined whether the random regression (RR) coefficient from 306 to 450 DIM (M2) can be predicted from those during the first 305 DIM (M1) by using a RR model. Methods: We analyzed test-day milk records from 85,690 Holstein cows in their first lactations and 131,727 cows in their later (second to fifth) lactations. Data in M1 and M2 were analyzed separately by using different single-trait RR animal models. We then performed a multiple regression analysis of the RR coefficients of M2 on those of M1 during the first and later lactations. Results: The first-order Legendre polynomials were practical covariates of RR for the milk yields of M2. All RR coefficients for the additive genetic (AG) effect and the intercept for the permanent environmental (PE) effect of M2 had moderate to strong correlations with the intercept for the AG effect of M1. The coefficients of determination for multiple regression of the combined intercepts for the AG and PE effects of M2 on the coefficients for the AG effect of M1 were moderate to high. The daily milk yields of M2 predicted by using the RR coefficients for the AG effect of M1 were highly correlated with those obtained by using the coefficients of M2. Conclusion: Milk production after 305 DIM can be predicted by using the RR coefficient estimates of the AG effect during the first 305 DIM.

• 응용통계연구
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• 제30권1호
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• pp.25-39
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• 2017

최근 경륜은 2015년도 기준, 5백만 명 이상의 많은 사람들이 참여하고 2조를 넘어선 매출을 발생시키는 대중적인 레저스포츠로서 자리 잡고 있다. 본 연구의 목적은 다양한 통계적 분석기법을 사용하여 경륜경기의 순위를 예측하고, 순위에 유의한 영향을 미치는 변수들을 파악하는 데에 있다. 다양한 Classification 방법과 Regression 방법들을 적용하여 순위예측모형을 만들고 비교분석하였다. 대부분의 모형에서 공통적으로 선택된 변수들을 살펴보면, 등급이 강급될수록, 종합득점이 높을수록 순위가 높아지며 반대로 등급이 승급될수록, 번호 4번을 부여받을수록 그리고 최근성적의 순위가 낮을수록 순위가 낮아지는 것을 알 수 있었다. 또한, 선수의 실력과 관련된 연속형 변수들을 각 경기별로 평균값을 빼서 보정한 자료와 원자료를 사용하여 모형을 적합시킨 결과 모든 모형에서 보정된 자료를 사용하였을 때 더 낮은 오분류율을 보였다. 마지막으로 분석에 사용하지 않은 최근 한 달 경기결과를 예측해서 베팅했을 때 모든 경우에 예측률은 높았지만 큰 이익을 거두지 못했는데 그 이유는 낮은 배당률을 가진 경기의 결과만을 잘 예측했기 때문이다.

• Structural Engineering and Mechanics
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• 제84권5호
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• pp.605-618
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• 2022

Glass fiber reinforced polymer (GFRP) elastic gridshells consist of long continuous GFRP tubes that form elastic deformations. In this paper, a method for the form-finding of gridshell structures is presented based on the interpretable machine learning (ML) approaches. A comparative study is conducted on several ML algorithms, including support vector regression (SVR), K-nearest neighbors (KNN), decision tree (DT), random forest (RF), AdaBoost, XGBoost, category boosting (CatBoost), and light gradient boosting machine (LightGBM). A numerical example is presented using a standard double-hump gridshell considering two characteristics of deformation as objective functions. The combination of the grid search approach and k-fold cross-validation (CV) is implemented for fine-tuning the parameters of ML models. The results of the comparative study indicate that the LightGBM model presents the highest prediction accuracy. Finally, interpretable ML approaches, including Shapely additive explanations (SHAP), partial dependence plot (PDP), and accumulated local effects (ALE), are applied to explain the predictions of the ML model since it is essential to understand the effect of various values of input parameters on objective functions. As a result of interpretability approaches, an optimum gridshell structure is obtained and new opportunities are verified for form-finding investigation of GFRP elastic gridshells during lifting construction.

• Safety and Health at Work
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• 제10권2호
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• pp.172-179
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• 2019

Background: Workers exposed to hazards without adequate protections are at greater risk of injury and illness. Supervisor activities have also been associated with injury risk. We examined the interplay between supervisor safety support and occupational health and safety (OHS) vulnerability on workplace injury and illness. Methods: A survey was administered to 2,390 workers employed for more than 15 hrs/week in workplaces with at least five employees who had a direct supervisor. We examined the combined effects of hazard exposure with inadequate protection (OHS vulnerability) and supervisor support on workplace injury and illness, using additive interactions in log-binomial regression models. Results: OHS vulnerability and lack of supervisor support independently increased the likelihood of physical injuries at work. Crude and adjusted models showed that the risk of physical injury was at least 3.5 times higher among those experiencing both OHS vulnerability and a lack of supervisor support than individuals without OHS vulnerability and with a supportive direct supervisor. Workers who experienced vulnerability were at less risk if they had a supervisor who was supportive. Conclusion: In workplaces where workers experience one or more types of OHS vulnerability, having a supportive supervisor may play an important role in reducing the risk of injury and protecting workers.