• The KSFM Journal of Fluid Machinery
• /
• v.8 no.6 s.33
• /
• pp.26-32
• /
• 2005

1.6 MW class supersonic partial admission impulse turbine has been designed and tested in Korea Aerospace Research Institute for the liquid rocket engine application. The test has been performed using a high pressure air source facility in KARI. For the turbine power absorption, a hydraulic dynamometer has been used. Appropriate similarity relations are used for the determination of test condition. Various settings of turbine pressure ratio and rotational speed are tested to investigate global turbine characteristics. From measured data, parameters related to the turbine design are derived and validated.

• Journal of Chest Surgery
• /
• v.26 no.12
• /
• pp.944-949
• /
• 1993

Clinical analysis were performed on 247 cases of thoracic trauma, those were admitted & treated at the department of thoracic & cardiovascular surgery,Hanyang University Hospital during the period from Jan,1989 to June,1992. Age distribution of those was from 2 to 80 years old & mean age was 38 years old. The ratio of male to female patient was 186:61 [3:1].This ratio revealed high incidence in male patient. The most common cause of trauma was traffic accident in this series.The modes of injury were as follows: traffic accident 124 cases[50.2%],fall down 52 cases[21.05%], stab wound 47 cases[19.03%] and gun-shut wound 1 case.Ellapse time from accident to admission were 141 cases [57.09%] under 6 hr.Rib fracture were observed in 159 cases[64.37%], hemo or pneumothorax were observed 134 cases[54.25%] of total cases and location distributed Right:Left:Both[74:112:37], in left predominant. Conservative,non-operative treatment were performed in 128 cases and operation[open thoracotomy] 32 cases.Mortality was 1.6%[4 cases] & most common cause of death were due to irreversible shock with brain edema. Conclusively, more evaluation & co-operation of other department were expected treatment & better prognosis.

• 유체기계공업학회:학술대회논문집
• /
• 2004.12a
• /
• pp.125-131
• /
• 2004

1.6 MW class supersonic partial admission impulse turbine has been designed and tested in Korea Aerospace Research Institute for the liquid rocket engine application. The test has been performed using a high pressure air source facility in KARI. For the turbine power absorption, a hydraulic dynamometer is used. Appropriate similarity relations are used for the determination of test condition. Various settings of turbine pressure ratio and rotational speed are tested to investigate global turbine characteristics. From measured data, Parameters related to the turbine design are derived and validated.

• Journal of Preventive Medicine and Public Health
• /
• v.40 no.1
• /
• pp.36-44
• /
• 2007

Objectives : There have been few studies examining the differences in health care utilization across social classes during the last year of life. Therefore, in this study we analyzed the quantitative and qualitative differences in health care utilization among cancer patients across educational classes in their last year of life, and derived from it implications for policy. Methods : To evaluate health care utilization by cancer patients in the last year of life, Death certificate data from 2004 were merged with National Health Insurance data (n=60,088). In order to use educational level as a social class index, we selected the individuals aged 40 and over as study subjects (n=57,484). We analyzed the differences in the medical expenditures, admission days, and rates of admission experience across educational classes descriptively. Multiple regression analysis was conducted to evaluate the association between medical expenditures and independent variables such as sex, age, education class, site of death and type of cancer. Results : The upper educational class spent much more on medical expenditures in the last one year of life, particularly during the last month of life, than the lower educational class did. The ratio of monthly medical expenditures per capita between the college class and no education class was 2.5 in the last 6-12 months of life, but the ratio was 1.6 in the last 1 month. Also, the lower the educational class, the higher the proportion of medical expenditures during the last one month of life, compared to total medical expenditures in the last one year of life. The college educational class had a much higher rate of admission experiences in tertiary hospitals within Seoul than the other education classes did. Conclusions : This study shows that the lower educational classes had qualitative and quantitative disadvantages in utilizing health care services for cancer in the last year of life.

• Korean Journal of Radiology
• /
• v.24 no.5
• /
• pp.434-443
• /
• 2023

Objective: To investigate the association between pelvic bone computed tomography (CT)-derived body composition and patient outcomes in older adult patients who underwent surgery for proximal femur fractures. Materials and Methods: We retrospectively identified consecutive patients aged ≥ 65 years who underwent pelvic bone CT and subsequent surgery for proximal femur fractures between July 2018 and September 2021. Eight CT metrics were calculated from the cross-sectional area and attenuation of the subcutaneous fat and muscle, including the thigh subcutaneous fat (TSF) index, TSF attenuation, thigh muscle (TM) index, TM attenuation, gluteus maximus (GM) index, GM attenuation, gluteus medius and minimus (Gmm) index, and Gmm attenuation. The patients were dichotomized using the median value of each metric. Multivariable Cox regression and logistic regression models were used to determine the association between CT metrics with overall survival (OS) and postsurgical intensive care unit (ICU) admission, respectively. Results: A total of 372 patients (median age, 80.5 years; interquartile range, 76.0-85.0 years; 285 females) were included. TSF attenuation above the median (adjusted hazard ratio [HR], 2.39; 95% confidence interval [CI], 1.41-4.05), GM index below the median (adjusted HR, 2.63; 95% CI, 1.33-5.26), and Gmm index below the median (adjusted HR, 2.33; 95% CI, 1.12-4.55) were independently associated with shorter OS. TSF index (adjusted odds ratio [OR], 6.67; 95% CI, 3.13-14.29), GM index (adjusted OR, 3.45; 95% CI, 1.49-7.69), GM attenuation (adjusted OR, 2.33; 95% CI, 1.02-5.56), Gmm index (adjusted OR, 2.70; 95% CI, 1.22-5.88), and Gmm attenuation (adjusted OR, 2.22; 95% CI, 1.01-5.00) below the median were independently associated with ICU admission. Conclusion: In older adult patients who underwent surgery for proximal femur fracture, low muscle indices of the GM and gluteus medius/minimus obtained from their cross-sectional areas on preoperative pelvic bone CT were significant prognostic markers for predicting high mortality and postsurgical ICU admission.

• Journal of Trauma and Injury
• /
• v.35 no.3
• /
• pp.181-188
• /
• 2022

Purpose: Inferior vena cava (IVC) collapse is related to hypovolemia. Sonography has been used to measure the IVC diameter, but there is variation depending on the skill of the operator and it is difficult to obtain accurate measurements in patients who have a large amount of intestinal gas or are obese. As a modality to obtain accurate measurements, we measured the diameters of the IVC and aorta on trauma computed tomography scans and investigated the correlation between the IVC to aorta ratio and the shock index in blunt trauma patients. Methods: We retrospectively analyzed the medical records of 588 trauma patients who were transferred to the regional trauma center (level 1) of Wonkang University Hospital from March 2020 to February 2021. We included trauma patients 18 years or older who met the trauma activation criteria and underwent trauma computed tomography scans with intravenous contrast within 40 minutes of admission. The shock index was calculated from vital signs before trauma computed tomography scan, and measurements of the anteroposterior diameter of the IVC (AP), the transverse diameter of the IVC (T), and aorta were made 10 mm above the right renal vein in the venous phase. Results: Overall, 271 patients were included in this study, of whom 150 had a shock index ≤0.7 and 121 had a shock index >0.7. The T to AP ratio and AP to aorta ratio were significantly different between groups. Cutoffs were identified for the T to AP ratio and AP to aorta ratio (2.37 and 0.62, respectively) that produced clinically useful sensitivity and specificity for predicting a shock index >0.7, demonstrating moderate accuracy (T to AP ratio: area under the curve, 0.71; sensitivity, 59%; specificity, 87% and AP to aorta ratio: area under the curve, 0.70; sensitivity, 55%; specificity, 91%). Conclusions: The T to AP ratio and AP to aorta ratio are useful for predicting hemorrhagic shock in trauma patients.

• International Journal of Computer Science & Network Security
• /
• v.23 no.4
• /
• pp.55-68
• /
• 2023

In recent years, the Television White Space (TVWS) has attracted the interest of many researchers due to its propagation characteristics obtainable between 470MHz and 790MHz spectrum bands. The plenty of unused channels in the TV spectrum allows the secondary users (SUs) to use the channels for broadband services especially in rural areas. However, when the number of SUs increases in the TVWS wireless network the aggregate interference also increases. Aggregate interferences are the combined harmful interferences that can include both co-channel and adjacent interferences. The aggregate interference on the side of Primary Users (PUs) has been extensively scrutinized. Therefore, resource allocation (power and spectrum) is crucial when designing the TVWS network to avoid interferences from Secondary Users (SUs) to PUs and among SUs themselves. This paper proposes a model to improve the resource allocation for reducing the aggregate interface among SUs for broadband services in rural areas. The proposed model uses joint power and spectrum hybrid Firefly algorithm (FA), Genetic algorithm (GA), and Particle Swarm Optimization algorithm (PSO) which is considered the Co-channel interference (CCI) and Adjacent Channel Interference (ACI). The algorithm is integrated with the admission control algorithm so that; there is a possibility to remove some of the SUs in the TVWS network whenever the SINR threshold for SUs and PU are not met. We considered the infeasible system whereby all SUs and PU may not be supported simultaneously. Therefore, we proposed a joint spectrum and power allocation with an admission control algorithm whose better complexity and performance than the ones which have been proposed in the existing algorithms in the literature. The performance of the proposed algorithm is compared using the metrics such as sum throughput, PU SINR, algorithm running time and SU SINR less than threshold and the results show that the PSOFAGA with ELGR admission control algorithm has best performance compared to GA, PSO, FA, and FAGAPSO algorithms.

• Journal of agricultural medicine and community health
• /
• v.37 no.2
• /
• pp.84-95
• /
• 2012

Background: In Korea, private health insurance has neglected to induce externality on national health insurance by moral hazard. Therefore, we conducted this study in order to explore the influence of private health insurance on unnecessary medical utilization among patients with cervical or lumbar sprain. Method: The study examined a population of 449 patients (admission, 384; out-patient; 85) diagnosed with simple cervical or lumbar sprain without neurological symptoms at 20 small hospitals or clinics in Gwangju and Jeollanam provinces from Jul. 1 to Aug. 31 2008. The data were collected using structured, self-administrated questionnaire which collected information such as whether or not the patient was admitted (as a dependent variable), whether or not they had private health insurance (as a independent variable), and covariates such as socio-demographic characteristics, the factors related to the sprain, and characteristics of the insurance provider. Results: From hierarchical multiple logistic regression analysis, it was found that the admission rate of patient with private health insurance was higher than that those without it (Odds ratio=3.31, 95% Confidence interval; 1.14-9.58), meaning that private health insurance was an independent factor influencing the admission of patients with these conditions. Other determinants of admission were patient age and physician referral. Conclusions: This study is the first empirical study to explore the influence of private health insurance on inducing moral hazard in admission services, specifically among patients with cervical or lumbar sprain. Regulation of benefits provided by private health insurance may be necessary, as the effect of this moral hazard may mean existence of externality.

• Proceedings of the Korean Operations and Management Science Society Conference
• /
• 2003.05a
• /
• pp.441-447
• /
• 2003

Recently there is a growing Interest In mobile cellula r network providing multimedia service. However, the link bandwidth of mobile cellular network is not sufficient enough to provide satisfactory services to use rs. To overcome this problem, an adaptive framework has been proposed in this study, we propose a new method of estimating DPR(degradation period ratio) in an adaptive multimedia network where the bandwidth of ongoing call can be dynamically adjusted during its lifetime. DPR is a QoS(quality of service) parameter which represents the ratio of allocated bandwidth below a pre-defined target to the whole service time of a call. We improve estimation method of DPR using DTMC(discrete time Markov chain) model. We also calculate mean degradation period and degradation probability more precisely than in existing studies. Under Threshold CAC(call admission control) algorithm, we present analytically how to guarantee QoS to users and illustrate the method by numerical examples. The proposed method is expected to be used as one of CAC schemes in guaranteeing predefined QoS level of DPR

• Korea Journal of Hospital Management
• /
• v.15 no.4
• /
• pp.43-62
• /
• 2010

This study provides an evidence on the determinants of the profitability of university hospital by analyzing university hospital-level data set of hospital performance during the year 2007 (32 university hospitals in total). For the study, a multiple regression model is employed in which profitability index obtained from the DEA computations, operating margin to total asset and gross revenue are used as the dependent variables, and a number of hospital operating characteristics are chosen as the independent variables such as ownership type, location, bed size, period of establishment, bed occupancy rate, admission ratio of outpatients, patients per medical specialist, personnel cost per patient, liabilities to total assets, current ratio, fixed ratio, total asset turnover, medical assistance rate and public indicator. First, the results indicate that the bed occupancy rate and liabilities to total assets are positively and significantly associated with operating margin to total asset. Second, number of beds, the bed occupancy rate and number of patients per medical specialist are positively and significantly associated with operating margin to gross revenue. Third, the bed occupancy rate, number of patients per medical specialist, liabilities to total assets, total asset turnover are positively and significantly associated with profitability index revealed from DEA.