• Journal of the Korean Society of Hazard Mitigation
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• v.10 no.4
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• pp.17-24
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• 2010

The hollow RC(Reinforced concrete) pier has the merit of lightweight pier compared with solid RC pier. However, the hollow RC pier shows a low ductile behavior due to brittle failure of inside concrete. To overcome this problem, the internally confined hollow reinforced concrete column has been developed. In this study, the behavior of internally confined hollow RC piers were evaluated with safety ratio, ductility, total material cost, the total weight of the pier, etc. The chosen parameters for the study are hollow ratio, thickness of internal steel tube, intervals between vertical re-bars, numbers of horizontal re-bars, and strength of concrete. As a result of parameters study, the usage of a minimum necessary thickness of the internal steel tube is the most effective.

• Journal of the Korean Society of Hazard Mitigation
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• v.10 no.4
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• pp.1-7
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• 2010

Recently, the damage of the farmhouse has been increased due to frequent collapsing accidents of the pipe greenhouse caused by the heavy snow load derived from unusual weather phenomena. However, the study about it is rare and tenuous so that the damage is happened repeatedly. Although there are a few ways to improve the greenhouse such as increasing section, decreasing the distance between rafters in order to avoid the collapsing accidents, those ways have some shortcomings like cost and frame ratio increase, etc. Therefore, this study performed the large displacement analysis considering geometric non-linearity on each load level with respect to many kind of reinforcement methods and analyzed combined strength ratio and stress so as to search the ways, which enhance the structural stability of greenhouse and minimize the frame ratio increase. As a result, this paper is aimed at suggesting the optimal reinforcement method model.

• Korean Journal of Radiology
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• v.24 no.7
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• pp.626-639
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• 2023

Objective: To investigate the association of clinical, pathologic, and magnetic resonance imaging (MRI) variables with progressive disease (PD) during neoadjuvant chemotherapy (NAC) and distant metastasis-free survival (DMFS) in patients with triple-negative breast cancer (TNBC). Materials and Methods: This single-center retrospective study included 252 women with TNBC who underwent NAC between 2010 and 2019. Clinical, pathologic, and treatment data were collected. Two radiologists analyzed the pre-NAC MRI. After random allocation to the development and validation sets in a 2:1 ratio, we developed models to predict PD and DMFS using logistic regression and Cox proportional hazard regression, respectively, and validated them. Results: Among the 252 patients (age, 48.3 ± 10.7 years; 168 in the development set; 84 in the validation set), PD was occurred in 17 patients and 9 patients in the development and validation sets, respectively. In the clinical-pathologic-MRI model, the metaplastic histology (odds ratio [OR], 8.0; P = 0.032), Ki-67 index (OR, 1.02; P = 0.044), and subcutaneous edema (OR, 30.6; P = 0.004) were independently associated with PD in the development set. The clinical-pathologic-MRI model showed a higher area under the receiver-operating characteristic curve (AUC) than the clinical-pathologic model (AUC: 0.69 vs. 0.54; P = 0.017) for predicting PD in the validation set. Distant metastases occurred in 49 patients and 18 patients in the development and validation sets, respectively. Residual disease in both the breast and lymph nodes (hazard ratio [HR], 6.0; P = 0.005) and the presence of lymphovascular invasion (HR, 3.3; P < 0.001) were independently associated with DMFS. The model consisting of these pathologic variables showed a Harrell's C-index of 0.86 in the validation set. Conclusion: The clinical-pathologic-MRI model, which considered subcutaneous edema observed using MRI, performed better than the clinical-pathologic model for predicting PD. However, MRI did not independently contribute to the prediction of DMFS.

• Journal of the Korean Society of Hazard Mitigation
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• v.6 no.4 s.23
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• pp.37-47
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• 2006

Urban development results in increased runoff volume and flowrates and shortening in time of concentration, which may cause frequent flooding downstream. Flow retardation structures to limit adverse downstream effects of urban storm runoff are used. There are various types of flow retardation measures include detention basins, retention basins, and infiltration basins. In basic planning phase, a number of planning models of detention ponds which decide storage volume by putting main variables were used to design detention ponds. The characteristics of hydrological parameters $\alpha,\;\gamma$ which are used in planning models of detention pond were analyzed. In this study, detention ponds data of Disaster Impact Assessment report at 22 sites were analyzed in order to investigate correlation between characteristic of urban drainage basin parameter and characteristics of detention pond parameter due to urbanization effects. The results showed that storage volume was influenced by peak discharge ratio $\alpha$ more than runoff coefficient ratio $\beta$ and peak discharge ratio $\alpha$ was influenced by runoff coefficient ratio $\beta$ less than regional parameter n. Storage ratio was mainly influenced by duration of design rainfall in the case of trapezoidal inflow hydrograph such as Donahue et al. method.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.22 no.3
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• pp.175-183
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• 2012

Objectives: This study developed a harmonized method for risk assessment based on the Hazard & Risk Evaluation of Chemicals (HREC) according to the Industrial Safety and Health Act (ISHA). Methods: Three preliminary studies, performed during 2010 and 2011 by the Occupational Safety and Health Research Institute and three academic research groups, were compared. The differences in risk assessment, especially in the dose-response assessment method, were analyzed. A new harmonized method for dose-response assessment was suggested and its applicability for the HREC was examined. Results: Considering the various steps of each dose-response assessment, the equivalent steps in quantitative correction, uncertainty factor 2 (UF2) for intra-species uncertainty, and UF3 for the experimental period in the uncertainty correction were relatively high. Using our new method, the total correction values (quantitative correction plus uncertainty correction) ranged from 72~15,789 to 30~60, and the ratio of the threshold limit value (TLV) to the reference concentration decreased from 12.8~1900 to 5.4~11.8. Furthermore, when we performed risk characterization by our new method, hazard quotient (HQ) values for chloroethylene, epichlorohydrin, and barium sulfate became 3.0, 14.1, and 1.13 respectively, whereas three previous studies reported HQ values of 7.1, 4580, and 87.3 considering reasonable maximum exposure (RME) conditions. HQs of the three chemicals were calculated to be 0.6, 2.4, and 0.1 respectively, when compared to their TLVs. Conclusions: Our new method could be applicable for the HREC because the total correction values and the ratio of TLVs were within reasonable ranges. It is also recommended that additional risk management measures be applied for epichlorohydrin, for which the HQ values were greater than 1 when compared with both reference values and the TLV. Our proposed method could be used to harmonize dose-response assessment methods for the implementation of risk assessment based on the HREC according to ISHA.

• The Journal of Industrial Distribution & Business
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• v.9 no.7
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• pp.43-52
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• 2018

Purpose - The main purpose of this paper is to examine the effect of children's age on maternal labor supply in Korea using survival analysis. Specifically, we focus on the career re-interruption of women having children under age 12, which has rarely been studied in the existing literature. Research design, data, and methodology - We use micro data from the Korea Labor and Income Panel Study (KLIPS) surveyed from 1998 to 2016. Instead of using a pre-school child dummy or the number of young children as an explanatory variable, 9 children's age dummies are included to capture the effect of nurturing 0 to 9 years old children. This study estimates the hazard of a woman's exiting the labor market after her first experience of the career interruption, rather than the hazard of the first career interruption itself. A Cox proportional hazard model is applied to numerically capture the impact of children's age on behavioral changes in maternal labor supply. The sample used in this analysis is women between 15 and 54 years old. Most of all, we restrict the sample to women who had at least a child between 0 and 12 years old at the time of quitting their jobs. Results - The Cox proportional hazard model estimates show a strong negative effect of a 0-year-old child on maternal labor supply. Mothers with newborns have a high hazard ratio of labor force exit after the re-entry. The hazard of women with infants is three times higher than those with children aged 10 to 18. Additionally, the results show that not only newborns, but also children in the age of school-entry have a negative impact on their mother's labor supply. Conclusions - The findings reveal that children's ages need to be properly expanded and included when analyzing the effect of children and their ages on married women's labor supply, especially on women's career re-interruption. A large negative effect of 7-year-old children on maternal labor supply found here indicates that supporting mothers with school age children as well as pre-school children is necessary to prevent mothers from leaving the labor market.

• 한국방재학회:학술대회논문집
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• 2007.02a
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• pp.632-635
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• 2007

Detention pond has an important role in peak flow reduction to mitigate flood damage. Design of detention pond is accomplished through the preliminary stage, planning stage, and design stage in general. New development projects produce increased peak flow and flow amounts. In this case it is necessary to design the detention pond easily and simply. The simple procedure of detention pond design is proposed in this study. The relevant variables are peak flow ratio ($\alpha$) for the before and after development, and storage ratio which is ratio of storage volume to flow amounts. Simplified method for the detention pond design with runoff reduction is easily used for practical purposes.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2008.05a
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• pp.71-74
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• 2008

In order to resolve the problems which appear after the clean large ingot production process, the impurities which are involved in the steel smelting process should be removed by developing cleaner materials. Through the rationalization of cogging process that is the first forging process of large ingot the quality is to be improved. For the sake of the optimization of an open die forging process and the improvement of the subject matter frequency ratio, a hazard precise die forging process must be developed and a Near Net Shape Forming accomplished. As a result, energy can be reduced by minimizing an after control process. In order to produce large axes and other forming parts, processing techniques are to be developed. In this context, this paper is a study about a reduction ratio, dies width ratio and rotary angles, the amount of overlap, and intends to analysis cogging processes, utilizing Deform-3D cogging module

• Journal of the Korean Data and Information Science Society
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• v.22 no.2
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• pp.217-225
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• 2011

It is important to find risk factors associated with mental disorder. Also the hazard ratio that represent the relationship of risk factors with illness is main interest in medicine. Thus we used odds ratio to explore the relationship between mental disorder and risk factors. On this paper, when we applied Bayesian network to delirium of mental disorder, we selected major risk factors and calculated odds ratio. Especially we identified odds ratio of single risk factors and multiple risk factors.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.21
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• pp.9453-9458
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• 2014

Background: Breast cancer is the second leading cause of cancer death for women in the United States. Differences in survival of breast cancer have been noted among racial and ethnic groups, but the reasons for these disparities remain unclear. This study presents the characteristics and the survival curve of two racial and ethnic groups and evaluates the effects of race on survival times by measuring the lifetime data-based half-normal model. Materials and Methods: The distributions among racial and ethnic groups are compared using female breast cancer patients from nine states in the country all taken from the National Cancer Institute's Surveillance, Epidemiology, and End Results cancer registry. The main end points observed are: age at diagnosis, survival time in months, and marital status. The right skewed half-normal statistical probability model is used to show the differences in the survival times between black Hispanic (BH) and black non-Hispanic (BNH) female breast cancer patients. The Kaplan-Meier and Cox proportional hazard ratio are used to estimate and compare the relative risk of death in two minority groups, BH and BNH. Results: A probability random sample method was used to select representative samples from BNH and BH female breast cancer patients, who were diagnosed during the years of 1973-2009 in the United States. The sample contained 1,000 BNH and 298 BH female breast cancer patients. The median age at diagnosis was 57.75 years among BNH and 54.11 years among BH. The results of the half-normal model showed that the survival times formed positive skewed models with higher variability in BNH compared with BH. The Kaplan-Meir estimate was used to plot the survival curves for cancer patients; this test was positively skewed. The Kaplan-Meier and Cox proportional hazard ratio for survival analysis showed that BNH had a significantly longer survival time as compared to BH which is consistent with the results of the half-normal model. Conclusions: The findings with the proposed model strategy will assist in the healthcare field to measure future outcomes for BH and BNH, given their past history and conditions. These findings may provide an enhanced and improved outlook for the diagnosis and treatment of breast cancer patients in the United States.