• Structural Engineering and Mechanics
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• v.53 no.5
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• pp.881-896
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• 2015

In this study, a method for fatigue performance estimation of deepwater steel catenary riser (SCR) under short-term vortex-induced vibration was investigated for selected S-N curves. General tendency between S-N curve capacity and fatigue performance was analysed. SCRs are generally used to transport produced oil and gas or to export separated oil and gas, and are exposed to various environmental loads in terms of current, wave, wind and others. Current is closely related with VIV and it affects fatigue life of riser structures significantly. In this regards, the process of appropriate S-N curve selection was performed in the initial design stage based on the scale of fabrication-related initial imperfections such as welding, hot spot, crack, stress concentration factor, and others. To draw the general tendency, the effects of stress concentration factor (SCF), S-N curve type, current profile, and three different sizes of SCRs were considered, and the relationship between S-N curve capacity and short-term VIV fatigue performance of SCR was derived. In case of S-N curve selection, DNV (2012) guideline was adopted and four different current profiles of the Gulf of Mexico (normal condition and Hurricane condition) and Brazil (Amazon basin and Campos basin) were considered. The obtained results will be useful to select the S-N curve for deepwater SCRs and also to understand the relationship between S-N curve capacity and short-term VIV fatigue performance of deepwater SCRs.

• Journal of Korean Society of Transportation
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• v.27 no.4
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• pp.127-135
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• 2009

Most traffic information that drivers receive while driving are stored in their short-term memory and disappear within a few seconds. Contemporary modeling approaches using a dummy variable can't fully explain this phenomenon. As such, this study proposes to use utility functions of real-time in-vehicle traffic safety information (IVTSI), analyzing its safety impacts based on empirical data from an on-site driving experiment at signalized intersection approach with a limited visibility. For this, a driving stability evaluation model is developed based on driver's driving speed choice, applying an ordered probit model. To estimate the specified utility functions, the model simultaneously accounts for various factors, such as traffic operation, geometry, road environment, and driver's characteristics. The results show three significant facts. First, a normal density function (exponential function) is appropriate to explain the utility of IVTSI proposed under study over time. Second, the IVTSI remains in driver's short-term memory for up to nearly 22 second after provision, decreasing over time. Three, IVTSI provision appears more important than the geometry factor but less than the traffic operation factor.

• Health Policy and Management
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• v.30 no.1
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• pp.72-81
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• 2020

Background: The out-of-pocket maximum is one of the distinctive healthcare systems which sets a ceiling on co-payment in order to reduce the burden of households from the unpredictable medical expenditure. However, this leads to an increase in the demand for healthcare services especially in long-term care hospitals (LTCHs) in Korea. Methods: This study analyzed the influence factor of medical service overuse of 165,592 inpatients in LTCHs which out-of-pocket maximum is applied, by utilizing data from the National Health Insurance Service (2016). Based on Anderson Model, the medical service overuse, as a dependent variable, was defined as long-stay admission more than 180 days at the LTCHs. Independent variable was comprised of predisposing factors (gender, age), enabling factors (income level, types of out-of-pocket maximum) and need factors (illness level, patient use of tertiary hospital). Results: The most powerful factor of medical service overuse in LTCHs was availability of pre-payment for the out-of-maximum (odds ratio [OR], 191.66; p<0.001). This tendency was found in high income level status (p<0.001). Furthermore, mild inpatients (OR, 1.50; p<0.001) which had no experience with the tertiary hospitals (OR, 2.06; p<0.001) were more relevant to the medical service overuse in LTCHs, compared to the severe inpatients. Conclusion: It is suggested that a separate standard of out-of pocket maximum with regards to LTCHs is required to secure the beneficial functions of long-term hospitals and prevent unnecessary financial leakage to achieve sustainable and financially sound National Health Insurance.

• Journal of the Korea institute for structural maintenance and inspection
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• v.20 no.2
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• pp.34-39
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• 2016

Structural behaviour of PSC box bridge, on which KTX train runs, is analysed up to 500 km/h speed considering 12 stages track irregularity and interaction between bridge and vehicle. To evaluate wheel forces and rotations of vehicle, lateral wheel forces, derail factor and offload factor calculated on the track combining the bridge and 170 m normal track are compared with existing allowed limits. Maximum longitudinal displacement and accumulated sliding distance of the brige bearings for simply supported and 2 span continuous PSC bridges are presented by each running speeds. Long-term friction tests based on EN-1337-2 are conducted between PTFE and DP-mate plates. Finally, the long-term friction tests are proposed to consider the increasing speed of next generation high-speed train.

• Proceedings of the Korean Nuclear Society Conference
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• 1996.05a
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• pp.185-190
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• 1996

RFSP is a computer program to do fuel management calculations for CANDU reactors. Its main function is to calculate neutron flux and power distributions using two-energy-group, three dimensional neutron diffusion theory. However, up to now the treatment has not been true two-group but actually "one-and-half groups". In other words, the previous (1.5-group) version of RFSP lumps the fast fission term into the thermal fission term. This is based on the POWDERPUFS-V Westcott convention. Also, there is no up-scattering term or bundle power over cell flux (H1 factor) for the fast group. While POWDERPUFS-V provides only 1.5 group properties, true two-group cross sections for the design and analysis of CAUDU reactors can be obtained from WIMS-AECL. To treat the full two-group properties, the previous RFSP version was modified by adding the fast fission, up-scatter terms, and H1 factor. This two-group version of RFSP is a convenient tool to accept lattice properties from any advanced lattice code (e.g. WIMS-AECL DRAGON, HELIOS...) and to apply to advanced fuel cycles. In this study, the modification to implement the true two-group treatment was performed only in the subroutines of the ＊SIMULATE module of RFSP. This module is the appropriate one to modify first, since it is used for the tracking of reactor operating histories. The modified two-group RFSP was evaluated with true two-group cross sections from WIMS-AECL. Some tests were performed to verify the modified two-group RFSP and to evaluate the effects of fast fission and up-scatter for three core conditions and four cases corresponding to each condition. The comparisons show that the two-group results are quite reasonable and serve as a verification of the modifications made to RFSP. To assess the long-term impact of the full 2-group treatment, it is necessary to simulate a long period (several months) of reactor history. It will also be necessary to implement the full two-group treatment of reactivity devices and assess the reactivity-device worths.ce worths.

• Korean Journal of Radiology
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• v.23 no.10
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• pp.998-1008
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• 2022

Objective: The present study aimed to assess the relationship between incidental abnormalities on thoracic computed tomography (CT) and mortality in a general screening population using a long-term follow-up analysis. Materials and Methods: We retrospectively collected the medical records and CT images of 840 participants (mean age ± standard deviation [SD], 58.5 ± 6.7 years; 564 male) who underwent thoracic CT at a single health promotion center between 2007 and 2010. Two thoracic radiologists independently reviewed all CT images and evaluated any incidental abnormalities (interstitial lung abnormality [ILA], emphysema, coronary artery calcification [CAC], aortic valve [AV] calcification, and pulmonary nodules). Kaplan-Meier analysis with log-rank and z-tests was performed to assess the relationship between incidental CT abnormalities and all-cause mortality in the subsequent follow-up. Cox proportional hazards regression was performed to further identify risk factors of all-cause mortality among the incidental CT abnormalities and clinical factors. Results: Among the 840 participants, 55 (6%), 171 (20%), 288 (34%), 396 (47%), and 97 (11%) had findings of ILA, emphysema, CAC, pulmonary nodule, and AV calcification, respectively, on initial CT. The participants were followed up for a mean period ± SD of 10.9 ± 1.4 years. All incidental CT abnormalities were associated with all-cause mortality in univariable analysis (p < 0.05). However, multivariable analysis further revealed fibrotic ILA as an independent risk factor for all-cause mortality (hazard ratio, 2.52 [95% confidence interval, 1.02-6.22], p = 0.046). ILA were also identified as an independent risk factor for lung cancer or respiratory disease-related deaths. Conclusion: Incidental abnormalities on screening thoracic CT were associated with increased mortality during the long-term follow-up. Among incidental CT abnormalities, fibrotic ILA were independently associated with increased mortality. Appropriate management and surveillance may be required for patients with fibrotic ILA on thoracic CT obtained for general screening purposes.

• Clinical and Experimental Reproductive Medicine
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• v.50 no.4
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• pp.292-298
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• 2023

Objective: Ovarian torsion is a gynecological disorder that causes ischemia-reperfusion injuries in the ovary. Our study investigated berberine's short- and long-term effects on ovarian ischemia-reperfusion injuries. Methods: This study included 28 Wistar albino female rats weighing 180 to 220 g, which were divided into four groups: sham (S), torsion/detorsion (T/D), torsion/ detorsion+single dose berberine (T/D+Bb), and torsion/detorsion+15 days berberine (T/D+15Bb). The torsion and detorsion model was applied in all non-sham groups. In the T/D+Bb group, a single dose of berberine was administered, while in the T/D+15Bb group, berberine was administered over a period of 15 days. After the rats were euthanized, their ovaries were excised. The left ovaries were used for histopathologic evaluation, which included ovarian injury scoring and follicle count, while the right ovaries were used for biochemical analyses (tissue transforming growth factor-β [TGF-β] and alpha-smooth muscle actin [α-SMA] levels). Results: The histopathologic evaluation scores for the ovaries were significantly lower in the T/D+B group (p<0.05) and the T/D+15B group (p<0.005) than in the T/D group. The follicle counts in the T/D group were lower than those in both the sham and treated groups (p<0.005). The TGF-β levels were significantly lower in the T/D+15B group (p<0.005), whereas the α-SMA levels did not show a significant difference. Conclusion: Both short- and long-term berberine use could potentially have therapeutic effects on ovarian torsion. Long-term berberine use exhibited anti-inflammatory effects by reducing TGF-β levels, thereby preventing ischemia-reperfusion injuries. Therefore, we suggest that long-term berberine use could be beneficial for ovarian torsion.

• Korea Journal of Hospital Management
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• v.16 no.3
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• pp.57-74
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• 2011

The purpose of this study is to analyze the relationship between the BSC model's non-financial factors such as learning and growth, internal process, customer and financial factor in general hospitals. To achieve research purpose, the data were collected from 293 employees of 5 hospitals using a standardized questionnaires which were constructed to include BSC model, and applied the structural equation modeling to examine the relationship between non-financial and financial factor. The results show that the learning and growth factor of the model has positive effects of the internal process and customer factor. The internal process and customer factor are strongly related to financial factor. Hospitals have to know non-financial factor which has positively relate to financial factor. Therefore, the results of this study help to enhance the health care center to become aligned and focused on implementing the long-term competitive strategy. This study proposes an effective performance indicators for general hospitals and it is expected to be likely to have positive influence upon enhancing services of general hospitals.

• Korea Journal of Hospital Management
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• v.20 no.4
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• pp.50-61
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• 2015

Advances in healthcare technology and rapid economic growth lead to the increased life expectancy and consequently the size of elderly population. Korea is one of the countries that are rapidly aging. Thus, it is particularly important to prepare for the aging society. Recently, the number of healthcare institutions for the elderly citizens has increased. The purpose of selecting a hospital for the elderly is, in general, maintenance of health rather than improvement of health receiving proper treatment. Unlike choosing a hospital for treatment, customers of a long term care hospital have a different set of factors to consider. Especially, when choosing a long term care hospital, the influence of patient's family is greater than the patient. This study examines the factors they consider for long term care hospital. A total of 198 questionnaires were collected from the families of actual patients of long term care hospitals. Twelve questionnaires were found to be non-usable because of missing and unsatisfactory responses. Consequently, 186 questionnaires were used for the analyses. Findings of this study are as follows. First, seven factors have been identified to consider when choosing a long term care hospital for the elderly. They include convenience of facilities, costs variety of facility programs, service hours, reputation, accessibility, quality of medical staff, medical facilities, and facility size. Second, This study measured both importance and satisfaction with these attributes and analyzed the difference between them. Satisfaction was lower than importance in the categories of convenience of facilities, costs, and programs, and accessibility. On the other hand, satisfaction was higher in terms of service hours, reputation, and quality of medical staff. Finally, the current study found positive impact of accessibility and quality of medical staff on reuse intention of a long term care hospital.

• Journal of The Korean Society of Clinical Toxicology
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• v.18 no.1
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• pp.18-25
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• 2020

Purpose: We studied the impact of arterial oxygen tension (PaO₂) on the long term neurologic outcome in patients with acute carbon monoxide poisoning. Methods: The study population included 311 patients who presented to emergency department with acute CO poisoning from January 2015 to January 2018. These patients underwent arterial blood gas testing at the time of presentation. The baseline demographic, clinical, laboratory, and clinical outcome data were recorded. The primary outcome of interest was the long term neurologic status. Results: The normoxia group was significantly older and it had a higher incidence of diffusion weighted MRI abnormality, and this group needed multiple HBO sessions compared to the group with moderate or severe hyperoxia. Also, the incidence of altered mentality at discharge was higher in the normoxia group than that of the moderate hyperoxia group. The incidence of a poor long term neurologic outcome was 11.3%. The incidence of a poor long term neurologic outcome decreased as the PaO₂ increased. The PaO₂ was significantly lower in patients with a poor long term neurologic outcome than that of the patients with a good outcome 198 (165.2 to 231.1) mmHg in the good outcome group vs. 154 (119-162) mmHg in poor outcome, p<0.001). In multivariate logistic regression analysis, PaO₂ was selected as an independent factor of the poor long-term neurologic outcome (OR 0.981 (95% CI: 0.968 to 0.995)) Conclusion: Higher PaO₂ was independently associated with a lower incidence of a poor long-term neurologic outcome.