• Journal of Korean Society of Coastal and Ocean Engineers
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• v.17 no.4
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• pp.280-293
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• 2005

In this study, a model to calculate the expected total construction cost has been developed by combining a model to calculate the sliding distance of a caisson of a vertical breakwater and a model to calculate the rehabilitation cost of a caisson. The optimal cross-section of a caisson of a vertical breakwater is defined as the cross-section that requires a minimum expected total construction cost within the allowable limit of caisson sliding. Two allowable limits are considered: 0.1 m of the expected sliding distance during the lifetime of the breakwater and 0.1 of the probability that the cumulative sliding distance during the lifetime of the breakwater is greater than 0.3 m. A discount rate has also been introduced to convert the future rehabilitation cost to the present value. The introduction of the discount rate reduces the expected total construction cost for the caissons designed for shorter return periods due to frequent rehabilitations. The present design method requires a smaller cross-section than the conventional deterministic method in shallow water depths, enabling us to design a caisson more economically. On the other hand, the above-mentioned allowable limits of caisson sliding show similar results for smaller water depths, while, for larger depths, the former requires a larger cross-section than the latter.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.35 no.2
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• pp.125-130
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• 2011

Since conventional optimization that is classified as a deterministic method does not consider the uncertainty involved in a modeling or manufacturing process, an optimum design is often determined to be on the boundaries of the feasible region of constraints. Reliability-based design optimization is a method for obtaining a solution by minimizing the objective function while satisfying the reliability constraints. This method includes an optimization process and a reliability analysis that facilitates the quantization of the uncertainties related to design variables. Moment-based reliability analysis is a method for calculating the reliability of a system on the basis of statistical moments. In general, on the basis of these statistical moments, the Pearson system estimates seven types of distributions and determines the reliability of the system. However, it is technically difficult to practically consider the Pearson Type IV distribution. In this study, we propose an enhanced Pearson Type IV distribution based on a kriging model and validate the accuracy of the enhanced Pearson Type IV distribution by comparing it with a Monte Carlo simulation. Finally, reliability-based design optimization is performed for a system with type IV distribution by using the proposed method.

• Journal of Korea Water Resources Association
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• v.50 no.11
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• pp.725-734
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• 2017

The main purpose of this study is to analyze runoff aggregation structure and energy expenditure pattern of Choyang creek basin within the framework of power law distribution. To this end geomorphologic factors of every point in the basin of interest, which define tractive force and stream power as well as drainage area, are extracted based on GIS, and their complementary cumulative distributions are graphically analyzed through fitting them to power law distribution. The results indicate that three distinct behavioral regimes are observed from the complementary cumulative distributions of three geomorphogic factors. Based on the parameter estimation of power law distribution by maximum likelihood drainage area and stream power can be judged as scale invariance factor without finite scale while tractive force as scale dependence factor with finite scale. Furthermore, it is judged that tractive force would not follow power law distribution because it shows limited complex system behaviors only within the small extent of scale. The exponent of power law distribution for drainage area obtained in this study by maximum likelihood is larger than the previous researches due to the difference of parameter estimation methodologies. And the exponent for stream power is smaller than the previous researches due to the scaling property of channel slope for the basin of interest.

• Korean Journal of Psychosomatic Medicine
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• v.30 no.1
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• pp.46-53
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• 2022

Objectives : This study aimed to assess the possible association of dental pain with suicidal ideation among adolescents by analysing data from the 2018 Korean Youth Risk Behavior Survey, a nationwide online survey. Methods : Of 62,823 adolescent middle and high school students in Korea, 60,040 participants were selected for analysis, after excluding cases with missing values. Participants were given a questionnaire about their self-evaluation of health including dental pain and suicidal ideation. Logistic regression analysis demonstrated the relationships between dental pain and suicidal ideation after controlling for potential confounding factors. Results : The proportion of Korean adolescents reporting suicidal ideation was 13.3%. The proportion of adolescents who experienced dental pain was 23.4%. Compared to adolescents who did not report dental pain, adolescents who reported experiencing dental pain were significantly more likely to experience suicidal ideation (OR=1.94, p<0.001). In two multivariate models, the relationships between dental pain and suicidal ideation (AOR=1.24, p<0.001) were statistically significant. Conclusions : Dental pain was associated with increased risk of suicidal ideation among Korean adolescents, even when controlling for sociodemographic factors and other health conditions. It is necessary to consider screening adolescent patients who present with dental pain for suicidal ideation.

• Korean Journal of Psychosomatic Medicine
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• v.30 no.2
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• pp.112-118
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• 2022

Objectives : Zolpidem is a common drug used in insomnia. However, there are several reports of side effects of the central nervous system or sleep related behavior in patients who took zolpidem. This study was conducted to investigate risk factors affecting sleep related behavior after taking zolpidem in inpatients. Methods : From January 1, 2019 to December 31, 2019, medical records of patients who took zolpidem hospitalized at Inha University Hospital were reviewed retrospectively. Results : 907 patients who took Zolpidem, 102 (11.2%) showed sleep related behavior, and if they were 65 years of age or older, men, taking antipsychotics, and taking antipsychotics and benzodiazepines at the same time, they were significantly more likely to show sleep related behavior. Conclusions : Risk factors for sleep-related behavior after use of zolpidem are estimated gender, elderly, antipsychotics, and combination of antipsychotics and benzodiazepines.

• Journal of the Korean Association of Geographic Information Studies
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• v.26 no.1
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• pp.132-144
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• 2023

Recently, the frequency and intensity of heat waves due to the increase in climate change temperature are increasing. Therefore, this study tried to compare the evaluation process and evaluation results of the heat wave disaster evaluation, which is the government's analysis of the heat wave disaster vulnerability and the risk evaluation method recently emphasized by the IPCC. The analysis of climate change disaster vulnerability is evaluated based on manuals and guidelines prepared by the government. Risk evaluation can be evaluated as the product of the possibility of a disaster and its impact, and it is evaluated using the Markov chain Monte Carlo simulation based on Bayesian estimation method, which uses prior information to infer posterior probability. As a result of the analysis, the two evaluation results for Busan Metropolitan City differed slightly in the spatial distribution of areas vulnerable to heat waves. In order to properly evaluate disaster vulnerable areas due to climate change, the process and results of climate change disaster vulnerability analysis and risk assessment must be reviewed, and consider each methodology and countermeasures must be prepared.

• Nuclear Engineering and Technology
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• v.25 no.4
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• pp.529-538
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• 1993

A stochastic way using continuous time Markov process is presented to model the one-dimensional nuclide transport in fractured rock matrix as an extended study for previous work ［1］. A nuclide migration model by the continuous time Markov process for single planar fractured rock matrix, which is considered as a transient system where a process by which the nuclide is diffused into the rock matrix from the fracture may be no more time homogeneous, is compared with a conventional deterministic analytical solution. The primary desired quantities from a stochastic model are the expected values and variance of the state variables as a function of time. The time-dependent probability distributions of nuclides are presented for each discretized compartment of the medium given intensities of transition. Since this model is discrete in medium space, parameters which affect nuclide transport could be easily incorporated for such heterogeneous media as the fractured rock matrix and the layered porous media. Even though the model developed in this study was shown to be sensitive to the number of discretized compartment showing numerical dispersion as the number of compartments are decreased, with small compensating of dispersion coefficient, the model agrees well to analytical solution.

• Clinical and Experimental Reproductive Medicine
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• v.33 no.3
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• pp.199-205
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• 2006

Objective: The aim of this study was to evaluate the correlation between severity of endometriosis and the incidence of endometrial polyp. Methods: The study population consisted of six hundred thirty-one women who had undergone laparoscopic operation due to infertility, severe dysmenorrhea or ovarian tumors. We divided two groups: 434 women with endometriosis (study group) and 197 women without the disease (control group). The presence of endometriosis was documented by diagnostic or therapeutic laparoscopic operation and the disease severity was scored according to revised The American Fertility Society classification. We confirmed the endometrial polyps by pathologic examination after hysteroscopic polypectomy, and compared endometrial polyp incidence according to severity of endometriosis. Results: There was no significant difference between groups with regard to age, mean duration of infertility. Endometrial polyps were found in 274 women (63.0%) with endometriosis and in 58 controls (29.8%, p=0.0000). The incidence of endometrial polyps differed significantly according to stage of endometriosis. The incidence of endometrial polyps were 77/142 (54.2%), 58/90 (64.4%), 73/108 (67.6%, p<0.05), 66/94 (70.2%, p<0.05) in endometriosis stage I, II, III, and IV. There was a linear correlation between stage of endometriosis and endometrial polyps incidence (p=0.008). Conclusion: Endometriosis is accompanied by endometrial polyps. This results showed positive correlation between severity of the endometriosis and incidence of endometrial polyps. It is the possible mechanism for low pregnancy rate in the severe endometriosis.

• Tuberculosis and Respiratory Diseases
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• v.66 no.6
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• pp.437-443
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• 2009

Background: The aim of this study was to consider the significance of pleural fluid adenosine deaminase (ADA) activity combined with lymphocyte/neutrophil (L/N) ratio in the diagnosis of tuberculous pleurisy (TBpl) in a region of intermediate prevalence of tuberculosis (TB). Methods: We collected data from 388 patients with exudative pleural effusions. The final diagnoses were compared to the results from our diagnostic method using pleural fluid ADA and L/N ratio. Results: 108 patients had a final diagnosis of TBpl; 102 cases had high levels of ADA ($\geq$40 IU/L). When we considered ADA $\geq$40 IU/L as a diagnostic criterion, the sensitivity was 94.4%, specificity 87.5%, and posttest posttest probability 74.5%. However, when we considered ADA $\geq$40 IU/L combined with the L/N ratio $\geq$0.75 as a diagnostic criterion, the specificity and post-test probability were rose to 97.5% and 93%, respectively. The other causes of high ADA and L/N ratios were lymphoma and metastatic carcinoma, but mass-like lesions were found on the chest radiographs or CT scans. Conclusion: To evaluate the causes of exudative pleural effusions in a region of intermediate prevalence of tuberculosis, we recommend measuring the pleural fluid ADA and L/N ratio first. If the result is high and malignancies are not suspected, it may be diagnostic of TBpl.

• Pediatric Infection and Vaccine
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• v.5 no.2
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• pp.221-229
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• 1998

Purpose : The symptom of urinary tract infection in children is non-specific and systemic compared to that of adults. So the diagnosis of UTI in children can be delayed. If UTI in children is not appropriately managed, it may he resulted in renal failure, hypertension, growth failure in adolescence because there are already documented renal scar or urinary tract abnormality in infection period. Especially upper UTI that involve renal parenchyme may be result in fatal complication. The purpose of this study is analyzing the relationship between acute reactive marker and $^{99m}TC$-DMSA renal scan in upper urinary tract infection. Methods : This study included 56 children admitted at Dankook University Hospital Pediatric Department in Jan. 1995~May. 1998. We analyzed quantatively the results of acute reactive marker(CRP, ESR, WBC), pyuria, fever and compared to those of sonographically find ing and $^{99m}TC$-DMSA renal scan. Comparison between groups were performed by the chi-square (x2) test and a p value of less than 0.05 was considered statistically significant. Results : 1) The number of boys less than 1 year of age was larger than that of girls. But the number of boys more than 1 year of age was reversed. 2) The higher me level of reactive marker (CRP, WBC), the more the probability of upper UTI. 3) The higher fever, the more the probability of upper UTI. 4) The more pyuria, the more probability of upper UTI. 5) The more higher the grade of vesicoureteral reflux, the more probability of upper UTI. 6) $^{99m}TC$-DMSA renal scan is more sensitive and more specific diagnostic tool than renal sonogram. Conclusion : The appearance of an abnormal $^{99m}TC$-DMSA renal scan is correlated with acute reactive marker (CRP, ESR, WBC), fever, pyuria. $^{99m}TC$-DMSA renal scan can be a good valuable predictor tool in upper UTI. So we can start early treatment and decrease the incidence of complication of upper urinary tract by above indicators before knowing the result of urine culture. And we can follow up the patients in more good relationships with their parents by telling them the duration of treatment and follow-up plan.