• ETRI Journal
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• v.22 no.4
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• pp.40-50
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• 2000

We apply a "sliding-window" Maximum Likelihood(ML) estimator to estimate traffic parameters On-Off source and develop a method for estimating stochastic predicted individual cell arrival rates. Based on these results, we propose a simple Connection Admission Control(CAC)scheme for delay sensitive services in broadband onboard packet switching satellite systems. The algorithms are motivated by the limited onboard satellite buffer, the large propagation delay, and low computational capabilities inherent in satellite communication systems. We develop an algorithm using the predicted individual cell loss ratio instead of using steady state cell loss ratios. We demonstrate the CAC benefits of this approach over using steady state cell loss ratios as well as predicted total cell loss ratios. We also derive the predictive saturation probability and the predictive cell loss ratio and use them to control the total number of connections. Predictive congestion control mechanisms allow a satellite network to operate in the optimum region of low delay and high throughput. This is different from the traditional reactive congestion control mechanism that allows the network to recover from the congested state. Numerical and simulation results obtained suggest that the proposed predictive scheme is a promising approach for real time CAC.

• Health Policy and Management
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• v.27 no.1
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• pp.30-38
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• 2017

Background: This study aims to analyze the behavioral changes of healthcare providers and influencing factors after the reviewer unification of auto insurance medical benefit claims by an independent review agency. Methods: The comparison data were collected from the second half of 2013 and the same period of 2014. The key indicators are the number of admission days, the number of outpatient visits, inpatient ratio, inpatient medical expenses, and outpatient medical expenses. Results: Four indicators (number of admission days, number of outpatient visits, inpatient ratio, and outpatient medical expenses) showed statistically significant drops, while one indicator (inpatient medical expenses) showed no significant change. Conclusion: The reviewer unification of auto insurance medical benefit claims by an independent review agency showed significant reduction in cost and patient days.

• The KSFM Journal of Fluid Machinery
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• v.16 no.3
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• pp.10-17
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• 2013

The organic Rankine cycle has been widely used to convert the renewable energy such as the solar energy, the geothermal energy, or the waste energy etc., to the electric power. Some previous studies focused to find what kind of refrigerant would be a best working fluid for the organic Rankine cycle. In this study, R245fa was chosen to the working fluid, and the cycle analysis was conducted for the output power of 30kW or less. In addition, properties (temperature, pressure, entropy, and enthalpy etc.) of the working fluid on the cycle were predicted when the turbine output power was controlled by adjusting the mass flowrate. The configuration of the turbine was a radial-type and the supersonic nozzles were applied as the stator. So, the turbine was operated in partial admission. The turbine efficiency and the optimum velocity ratio were considered in the cycle analysis for the low partial admission rate. The computed results show that the system efficiency is affected by the partial admission rate more than the temperature of the evaporator.

• 유체기계공업학회:학술대회논문집
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• 2006.08a
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• pp.275-278
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• 2006

A steam turbine is one of propulsion systems of a LNG carrier, which consists of high pressure (HP) and low pressure (LP) turbines. In order to obtain high power, each one has the form of a multi-stage turbine. Especially, the first stage of a HP turbine is Curtis stage and uses partial admission considering the turbine efficiency. The performance of a HP turbine can be predicted by a mean-line analysis method, because the relatively large value of hub-tip ratio makes the three-dimensional losses small. In this study, a performance analysis method is developed for a multi-stage HP turbine using Chen's loss model developed for the transonic steam turbines. To consider the feature of partial admission, different partial admission models are reviewed, This analysis method can be used in partial load conditions as well as full load condition. The calculation results are also compared with the CFD results about some simple cases to check the accuracy of the program. Performance of two HP turbine models are calculated, and the calculation results are compared with the designed data. The comparison shows the qualitative performance analysis result.

• Journal of Korean Neurosurgical Society
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• v.67 no.2
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• pp.177-185
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• 2024

Objective : Delayed cerebral ischemia (DCI) is a major cause of disability in patients who survive aneurysmal subarachnoid hemorrhage (aSAH). Systemic inflammatory markers, such as peripheral leukocyte count and systemic immune-inflammatory index (SII) score, have been considered predictors of DCI in previous studies. This study aims to investigate which systemic biomarkers are significant predictors of DCI. Methods : We conducted a retrospective, observational, single-center study of 170 patients with SAH admitted between May 2018 and March 2022. We analyzed the patients' clinical and laboratory parameters within 1 hour and 3-4 and 5-7 days after admission. The DCI and non-DCI groups were compared. Variables showing statistical significance in the univariate logistic analysis (p<0.05) were entered into a multivariate regression model. Results : Hunt-Hess grade "4-5" at admission, modified Fisher scale grade "3-4" at admission, hydrocephalus, intraventricular hemorrhage, and infection showed statistical significance (p<0.05) on a univariate logistic regression. Lymphocyte and monocyte count at admission, SII scores and C-reactive protein levels on days 3-4, and leukocyte and neutrophil counts on days 5-7 exhibited statistical significance on the univariate logistic regression. Multivariate logistic regression analysis revealed that monocyte count at admission (odds ratio [OR], 1.64; 95% confidence interval [CI], 1.04-2.65; p=0.036) and SII score at days 3-4 (OR, 1.55; 95% CI, 1.02-2.47; p=0.049) were independent predictors of DCI. Conclusion : Monocyte count at admission and SII score 3-4 days after rupture are independent predictors of clinical deterioration caused by DCI after aSAH. Peripheral monocytosis may be the primer for the innate immune reaction, and the SII score at days 3-4 can promptly represent the propagated systemic immune reaction toward DCI.

• Tuberculosis and Respiratory Diseases
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• v.84 no.2
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• pp.125-133
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• 2021

Background: The coronavirus disease (COVID-19) can manifest in a range of symptoms, including both asymptomatic systems which appear nearly non-existent to the patient, all the way to the development of acute respiratory distress syndrome (ARDS). Specifically, COVID-19-associated pneumonia develops into ARDS due to the rapid progression of hypoxia, and although arterial blood gas analysis can assist in halting this deterioration, the current environment provided by the COVID-19 pandemic, which has led to an overall lack of medical resources or equipment, has made it difficult to administer such tests in a widespread manner. As a result, this study was conducted in order to determine whether the levels of oxygen saturation (SpO₂) and the fraction of inhaled oxygen (FiO₂) (SF ratio) can also serve as predictors of ARDS and the patient's risk of mortality. Methods: This was a retrospective cohort study conducted from February 2020 to Mary 2020, with the study's subjects consisting of COVID-19 pneumonia patients who had reached a state of deterioration that required the use of oxygen therapy. Of the 100 COVID-19 pneumonia cases, we compared 59 pneumonia patients who required oxygen therapy, divided into ARDS and non-ARDS pneumonia patients who required oxygen, and then investigated the different factors which affected their mortality. Results: At the time of admission, the ratios of SpO₂, FiO₂, and SF for the ARDS group differed significantly from those of the non-ARDS pneumonia support group who required oxygen (p<0.001). With respect to the predicting of the occurrence of ARDS, the SF ratio on admission and the SF ratio at exacerbation had an area under the curve which measured to be around 85.7% and 88.8% (p<0.001). Multivariate Cox regression analysis identified that the SF ratio at exacerbation (hazard ratio [HR], 0.916; 95% confidence interval [CI], 0.846-0.991; p=0.029) and National Early Warning Score (NEWS) (HR, 1.277; 95% CI, 1.010-1.615; p=0.041) were significant predictors of mortality. Conclusion: The SF ratio on admission and the SF ratio at exacerbation were strong predictors of the occurrence of ARDS, and the SF ratio at exacerbation and NEWS held a significant effect on mortality.

• Journal of Trauma and Injury
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• v.23 no.2
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• pp.113-118
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• 2010

Purpose: Prolonged stay in the emergency department (ED), which is closely related with the time interval from the ED visit to a decision to admit, might be associated with poor outcomes for trauma patients and with overcrowding of the ED. Therefore, we examined the factors affecting the delay in the decision to admit severe trauma patients. Also, a multidisciplinary department system was preliminarily evaluated to see if it could reduce the time from triage to the admission decision. Methods: A retrospective observational study was conducted at a tertiary care university hospital without a specialized trauma team or specialized trauma surgeons from January 2009 to March 2010. Severe trauma patients with an International Classification of Disease Based Injury Severity Score (ICISS) below 0.9 were included. A multivariable logistic regression analysis was used to find independent variables associated with a delay in the decision for admission which was defined as the time interval between ED arrival and admission decision exceeded 4 hours. We also simulated the time from triage to the decision for admission by a multidisciplinary department system. Results: A total of 89 patients were enrolled. The average time from triage to the admission decision was $5.2{\pm}7.1$ hours and the average length of the ED stay was $9.0{\pm}11.5$ hours. The rate of decision delay for admission was 31.5%. A multivariable regression analysis revealed that multiple trauma (odds ratio [OR]: 30.6, 95%; confidence interval [CI]: 3.18-294.71), emergency operation (OR: 0.55, 95%; CI: 0.01-0.96), and treatment in the Department of Neurosurgery (OR: 0.07, 95%; CI: 0.01-0.78) were significantly associated with the decision delay. In a simulation based on a multidisciplinary department system, the virtual time from triage to admission decision was $2.1{\pm}1.5$ hours. Conclusion: In the ED, patients with severe trauma, multiple trauma was a significant factor causing a delay in the admission decision. On the other hand, emergency operation and treatment in Department of Neurosurgery were negatively associated with the delay. The simulated time from triage to the decision for admission by a multidisciplinary department system was 3 hours shorter than the real one.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.2A
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• pp.61-65
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• 2005

We propose a soft QoS-based borrowing scheme for call admission control(CAC) in DVB-RCS(Digital Video Broadcast-Return Channel via Satellite). Some of the ongoing calls temporarily and fairly release bandwidths that can be used to accommodate a new call in an overloaded satellite network. The amount of bandwidth borrowed from each call is proportional to each user's critical bandwidth ratio, one of parameters for soft QoS mechanism. Simulation results show that the proposed scheme improves the system performance in terms of call blocking probability and bandwidth utilization.

• The KIPS Transactions:PartC
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• v.9C no.2
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• pp.297-306
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• 2002

Continuous multimedia applications require a guaranteed retricval and transfer rate of streaming data, which conventional file server mechanism generally does not provide. In this paper we describe a dynamic negotiated admission control and dick bandwidth scheduling framework for Continuous Media (CM : e.g., video) servers. The framework consists of two parts. One is a reserve-based admission control mechanism and the other part is a scheduler for continuous media streams with dynamic resource allocation to achieve higher utilization than non-dynamic scheduler by effectively sharing available resources among contending streams to improve overall QoS. Using our policy, we could increase the number of simultaneously running: clients that coo]d be supported and cot]d ensure a good response ratio and better resource utilization under heavy traffic requirements.

• Health Policy and Management
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• v.29 no.2
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• pp.237-244
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• 2019

Background: Weekend admission is known for having association with increased mortality attributed by poor quality of care and severe patients. We investigated the association between hospital admission on weekends and the in-hospital mortality rates of patients with cardiovascular disease. Furthermore, we examined this association stratified by admission via emergency room or not. Methods: We analyzed claim data provided by the Health Insurance Review & Assessment in 2013. In total, 80,817 cardiovascular patients were included in this study, which treated in-hospital mortality (early and during total length of stay) as a dependent variable. A generalized linear mixed effects model was used. We conducted subgroup analyses stratified by admission via emergency room or not. Results: Patients who admitted on weekend showed higher in-hospital mortality both early (odds ratio [OR], 1.48; 95% confidence interval [CI], 1.23-1.78) and during total length of stay (OR, 1.17; 95% CI, 1.02-1.33) compared to those admitted on weekdays. Patients who were admitted to the hospital on a weekend by emergency room were more likely to experience early in-hospital mortality compared to those admitted on weekdays. Furthermore, we found that patients not admitted to the hospital through the emergency department were more likely to experience both early and total length of stay in-hospital mortality. Conclusion: Our study shows higher in-hospital mortality rates for cardiovascular patients admitted on weekends. Efforts to improve the quality of care on weekend are important to mitigate the 'weekend effect' and improve patient outcomes.