• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2004.08a
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• pp.146-154
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• 2004

Evaluating the risk of collision quantitatively plays a key role in developing the expert system of navigation and collision avoidance. This study suggested and developed a new approach to the evaluation by using the sech function as an alternative to the existing methods of appraising the collision risk. This study also investigated and built up theoretically how to determine the gradient coefficients in this approach and suggested the appropriate values as much as applicable. Finally this study analyzed thoroughly how to determine the threshold function of avoiding time and developed the appropriate equation.

• Journal of Navigation and Port Research
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• v.27 no.4
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• pp.351-357
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• 2003

Evaluating the risk of collision quantitatively plays a key role in developing the expert system of navigation and collision avoidance. This study analysed theoretically and thoroughly how to determine the gradient coefficients as described in the new evaluation of collision risk using sech function, and suggested the appropriate values as applicable.

• Communications for Statistical Applications and Methods
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• v.30 no.1
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• pp.1-19
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• 2023

Observational data with missing or incomplete data are common in biomedical research. Multiple imputation is an effective approach to handle missing data with the ability to decrease bias while increasing statistical power and efficiency. In recent years propensity score (PS) matching has been increasingly used in observational studies to estimate treatment effect as it can reduce confounding due to measured baseline covariates. In this paper, we describe in detail approaches to competing risk analysis in the setting of incomplete observational data when using PS matching. First, we used multiple imputation to impute several missing variables simultaneously, then conducted propensity-score matching to match statin-exposed patients with those unexposed. Afterwards, we assessed the effect of statin exposure on the risk of heart failure-related hospitalizations or emergency visits by estimating both relative and absolute effects. Collectively, we provided a general methodological framework to assess treatment effect in incomplete observational data. In addition, we presented a practical approach to produce overall cumulative incidence function (CIF) based on estimates from multiple imputed and PS-matched samples.

• Journal of East-West Nursing Research
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• v.25 no.2
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• pp.183-192
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• 2019

Purpose: This study aimed to examine the mediating effect of illness perception on the relationship between family function and health behavior of patients with risk factors for metabolic syndrome. Methods: This is a cross-sectional correlational study. Data were collected from 160 patients using self-administered questionnaires including the Illness Perception Questionnaire-Revised, Family APGAR, and the Health Behavior Scale. The data were analyzed using Pearson's correlation coefficients, independent t-test and multiple linear regression analysis by the SPSS 23.0 program. Results: Health behavior was significantly correlated with family function (r=.30, p<.001) and illness perception of controllability by treatment (r=-.21, p=.007). Family function was a significant predictor of health behavior and illness perception, and the influence of family function on health behavior was partially mediated by illness perception of controllability by treatment. Conclusion: The findings of this study indicate that family function is a critical factor affecting health behavior and illness perception, and illness perception of controllability by treatment mediates the influence of family function on health behavior. It is necessary to develop a psycho-cognitive intervention program for enhancing supportive family function and for modifying negative illness perceptions to improve health behavior in patients with risk factors for metabolic syndrome.

• Journal of the Korean Society of Costume
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• v.53 no.7
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• pp.29-36
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• 2003

The purposes of this syudy were to identify the factors of perceived risk, satisfaction, and intention on rental clothing. The subjects were 767 adults residing in Jeonbuk province. The research was made from February 20 to March 19, 2003. Fof data analysis. frequencies, percentages, mean, and standard deviations were calculated. Also, factor analysis and stepwise multiple-regression analysis were done. The results were as follows: 1. Approximately half of the respondents had experiences of rental clothing, and the most frequent items were wedding dress, degree gown, performance dress, and sports wear in descending order. 2. The factors of perceived risk of rental clothing were divided into lost, appropriateness, and damage, and total variance was 62.51%. The perceived risk about damage of rental clothing was the highest, and lost was the lowest. 3. The factors of rental clothing satisfaction were divided into appearances, store status, function, and fitness, and total variance was 59.96%. The satisfaction of function of rental clothing was the highest, and the store status was the lowest. 4. The intention on rental clothing was high in case of higher interest in rental clothing, higher educational level. more experiences in rental clothing, lower perceived risk of damage on the rental clothing, and younger person, and these variables explained 54.00% of the intention on rental clothing.

• Journal of the Earthquake Engineering Society of Korea
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• v.27 no.6
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• pp.265-273
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• 2023

This study proposes a methodology for the regional seismic risk assessment of structural damage to buildings in Korea based on evaluating individual buildings, considering inconsistency between the administrative district border and grid lines to define seismic hazard. The accuracy of seismic hazards was enhanced by subdividing the current 2km-sized grids into ones with a smaller size. Considering the enhancement of the Korean seismic design code in 2005, existing seismic fragility functions for seismically designed buildings are revised by modifying the capacity spectrum according to the changes in seismic design load. A seismic risk index in building damage is defined using the total damaged floor area considering building size differences. The proposed seismic risk index was calculated for buildings in 29 administrative districts in 'A' city in Korea to validate the proposed assessment algorithm and risk index. In the validation procedure, sensitivity analysis was performed on the grid size, quantitative building damage measure, and seismic fragility function update.

• Journal of Navigation and Port Research
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• v.36 no.10
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• pp.795-801
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• 2012

This paper describes theoretical approach methodology for the Probability based risk Evaluation Techniques (PET) to monitor the risk levels of small-sized sea floater as like a yacht pier. The risk decision-making process by risk criteria with five-step scales is the core concepts of PET. These five-step scales are calculated from cumulative probability distribution of response functions for the sea floater motions using closed-form expressions. In addition, The risk decision-making process of PET with the risk criteria is proposed in this work. To verify the usability of PET, simulation experiments are carried out using mimic signals with the electrical specifications of ADIS16405 sensor that is to be use as measurement tool for the floater motions. As results from experiments, the risk evaluation error by PET shows 0.38 levels in maximum 5.0 levels. These results clearly shown that the proposed PET can be use as the monitoring techniques.

• Journal of Korean Neurosurgical Society
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• v.56 no.1
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• pp.28-33
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• 2014

Objective : Postoperative delirium is a common complication in the elderly after surgery but few papers have reported after spinal surgery. We analyzed various risk factors for postoperative delirium after spine surgery. Methods : Between May 2012 and September 2013, 70 patients over 60 years of age were examined. The patients were divided into two groups : Group A with delirium and Group B without delirium. Cognitive function was examined with the Mini-Mental State Examination-Korea (MMSE-K), Clinical Dementia Rating (CDR) and Global Deterioration Scale (GDS). Information was also obtained on the patients' education level, underlying diseases, duration of hospital stay and laboratory findings. Intraoperative assessment included Bispectral index (BIS), type of surgery or anesthesia, blood pressure, fluid balance, estimated blood loss and duration of surgery. Results : Postoperative delirium developed in 17 patients. The preoperative scores for the MMSE, CDR, and GDS in Group A were $19.1{\pm}5.4$, $0.9{\pm}0.6$, and $3.3{\pm}1.1$. These were significantly lower than those of Group B ($25.6{\pm}3.4$, $0.5{\pm}0.2$, and $2.1{\pm}0.7$) (p<0.05). BIS was lower in Group A ($30.2{\pm}6.8$ compared to $35.4{\pm}5.6$ in group B) (p<0.05). The number of BIS <40 were $5.1{\pm}3.1$ times in Group A, $2.5{\pm}2.2$ times in Group B (p<0.01). In addition, longer operation time and longer hospital stay were risk factors. Conclusion : Precise analysis of risk factors for postoperative delirium seems to be more important in spinal surgery because the surgery is not usually expected to have an effect on brain function. Although no risk factors specific to spinal surgery were identified, the BIS may represent a valuable new intraoperative predictor of the risk of delirium.

• Atmosphere
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• v.34 no.1
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• pp.1-21
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• 2024

Private companies are increasingly required to take more substantial actions on climate change. This study introduces the principle and cases of climate (physical) risk estimation for 11 private companies in Korea. Climate risk is defined as the product of three major determinants: hazard, exposure, and vulnerability. Hazard is the intensity or frequency of weather phenomena that can cause disasters. Vulnerability can be reflected in the function that explains the relationship between past weather records and loss records. The final climate risk is calculated by multiplying the function by the exposure, which is defined as the area or value of the target area exposed to the climate. Future climate risk is estimated by applying future exposure to estimated future hazard using climate model scenarios or statistical trends based on weather data. The estimated climate risks are developed into three types according to the demand of private companies: i) climate risk for financial portfolio management, ii) climate risk for port logistics management, iii) climate risk for supply chain management. We hope that this study will contribute to the establishment of the climate risk management system in the Korean industrial sector as a whole.

• Journal of the Korean Statistical Society
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• v.22 no.2
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• pp.191-200
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• 1993

An asymptotic estimation problem of the unknown mean is studied under a general loss function. The proof of this result is based on the asymptotic expansion of the risk function. Also conditions for second order admissibility and minimaxity of a class of estimators depending only on the sample mean are established.