• Journal of Korean Neurosurgical Society
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• v.63 no.6
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• pp.827-833
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• 2020

Objective : Spine surgery is associated with higher morbidity and mortality rates in elderly patients. The modified Frailty Index (mFI) is an evaluation tool to determine the frailty of an individual and how preoperative status may impact postoperative survival and outcomes. This study aimed to determine the usefulness of mFI in predicting postoperative complications in patients aged ≥75 years undergoing surgery with instrumentation. Methods : We retrospectively reviewed the perioperative course of 137 patients who underwent thoracolumbar-instrumentation spine surgery between 2011 and 2016. The preoperative risk factors were the 11 variables of the mFI, as well as body mass index (kg/㎠), preoperative hemoglobin, platelet, albumin, creatinine, anesthesia time, operation time, estimated blood loss, and transfusion amount. The 60-day occurrences of complication rates were used for outcome assessment. Results : Major complications after spinal instrumentation surgery occurred in 34 of 138 patients (24.6%). The mean mFI score was 0.18±0.12. When we divided patients into a pre-frail group (mFI, 0.09-0.18; n=94) and a frail group (mFI ≥0.27; n=44), only the rate of sepsis was statistically higher in the frail group than in the pre-frail group. There were significantly more major complications in patients with low albumin levels or in patients with infection or who had experienced trauma. The mFI was a more useful predictor of postoperative complications than the American Society of Anesthesiologists physical status score. Conclusion : The mFI can successfully predict postoperative morbidity and mortality in patients aged ≥75 years undergoing spine surgery. The mFI improves perioperative risk stratification that provides important information to assist in the preoperative counselling of patients and their families.

• Journal of Korea Multimedia Society
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• v.13 no.3
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• pp.417-429
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• 2010

Though background subtraction has been widely studied for last decades, it is still a poorly solved problem especially when it meets real environments. In this paper, we first address some common problems for background subtraction that occur in real environments and then those problems are resolved by improving an existing GMM-based background modeling method. First, to achieve low computations, fixed point operations are used. Because background model usually does not require high precision of variables, we can reduce the computation time while maintaining its accuracy by adopting fixed point operations rather than floating point operations. Secondly, to avoid erroneous backgrounds that are induced by high pedestrian traffic, static levels of pixels are examined using shot-time statistics of pixel history. By using a lower learning rate for non-static pixels, we can preserve valid backgrounds even for busy scenes where foregrounds dominate. Finally, to adapt rapid illumination changes, we estimated the intensity change between two consecutive frames as a linear transform and compensated learned background models according to the estimated transform. By applying the fixed point operation to existing GMM-based method, it was able to reduce the computation time to about 30% of the original processing time. Also, experiments on a real video with high pedestrian traffic showed that our proposed method improves the previous background modeling methods by 20% in detection rate and 5~10% in false alarm rate.

• Korean Chemical Engineering Research
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• v.47 no.1
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• pp.111-118
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• 2009

A hybrid SNCR/SCR plant was designed and manufactured, and experimented on the SNCR process in the first step to investigate the optimum operation conditions of SNCR, with the equivalence ratio of the reducing agent(NSR, 0.5~5.0), reaction temperature($850{\sim}1,100^{\circ}C$), nozzle type(wall nozzle, pipe nozzle), and nozzle position as variables. In the case of wall nozzles, the NOx reduction efficiency rapidly increased to 87% at 2.5 NSR and slowed down after this. Compared to the upward spray from the pipe nozzle, wall nozzles have narrower range of applicable reaction temperature. In the case of pipe nozzles, it rapidly increased to 77% at 1.5 NSR. But the pipe nozzle downward had no NOx reduction efficiency; on the contrary, NOx increased. When the reducing agent was sprayed upward from a pipe nozzle, the NOx reduction efficiency was 50~75% in the range of 0.5~1.5 NSR, and the NOx reduction efficiency was constant without fluctuations even in the change of reaction temperature from 890 to $1,000^{\circ}C$. When 5% urea solution was sprayed upward from the pipe nozzle, 200 ppm NOx decreased to approximately 60 ppm at 1.2 NSR, and the non-reacted $NH_3$ was 50~100 ppm. In this condition, we expect over 90% NOx reduction efficiency without additional supply of $NH_3$ to SCR at the back of SNCR.

• Journal of Korean Society for Geospatial Information Science
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• v.4 no.2 s.8
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• pp.55-61
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• 1996

The objective of this paper is to show an optimal design model for branched water supply system which also can find the optimal location of pumping stations using linear programming. GIS is utilized in this model to better handle the data and the results front the optimization. The developed model considers hydraulic influences of some appurtenances such as supply tunnels and a filtration plant The model also considers tunnel construction cost which should be treated differently from pipe construction cost Different from other models presently available, the model guarantees a nonnegative pressure at every junction node in the system. The objective function includes annual operation cost (electricity rate) ill addition to initial construction cost, thus producing a more reasonable decision. The model selects the optimal diameter not in the form of continuous number but in the form of commercial discrete diameter (pipe size) using the pipe lengths as decision variables instead of pipe diameters. The model not only determines the optimal pumping head for each pumping station but also finds the optimal location and number of pumping stations. GIS is used to handle hydraulic and budgetary data automatically and to visualize the results for the of optimal design of the system. The model has been applied to an existing water supply system. 'The results show that the optimization model with the aid of GIS is helpful in the decision-nulling process for the design of more economical systems, and can be dot into practice successfully.

• Journal of the Korean Association of Geographic Information Studies
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• v.21 no.1
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• pp.46-56
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• 2018

This paper aimed to identify main factors of community characters, which have an effect on the land surface temperature(LST) change and estimate the impacting coefficient(ratio) of factors in a significant level of statistics. Chungcheongbuk-do province was selected and then partitioned into city and county areas for the sake of convenience of modeling. LST time series data and the community character data were developed based on Terra Satellite MODIS data and collected from the National Statistical Office, respectively. By the cause and effect relationship between community characters and LST, regression coefficients were estimated using a penal model. In a panel modeling, LST and community characters were used as a dependent variable and explanatory variables, respectively. Panel modeling analysis was carried out using statistical package STATA14 and one-way fixed effect model was selected as the most suitable model to evaluate the regression coefficients in the study area. The impacting ratio of LST change by any explanatory variable derived from the regression coefficients of the panel model fixed. Impacting ratios for industrial areas, elevation ${\times}$ building, energy usage, average window speed, non-urban management area, agricultural, nature and environmental conservation, average precipitation were 3.746, 2.856, 2.742, 0.553, 0.102, 0.071 and 0.003, respectively.

• Journal of Life Science
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• v.17 no.4 s.84
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• pp.515-521
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• 2007

Aprotinin, a serine protease inhibitor, has been used to ameliorate the inevitable consequences, including blood component injury after cardiac surgery with cardiopulmonary bypass (CPB). However, there are many arguments on its dosage or usage. We assessed whether administration of low dose of aprotinin in only priming solution has any beneficial effect or reduces its side effects on cardiac surgery. Thirty patients scheduled for elective cardiac surgery were randomly assigned to aprotinin group (n=15) which received aprotinin in priming solution (two million kallikrein inhibitory unit, KIU) and added one million KIU at 1 hour after the beginning of CPB or control group (n=15) which did not receive it. Hematological and biochemical variables, cytokines and cardiac marker levels, and postoperative outcomes were compared between two groups at before, during or after operation. Platelet count in aprotinin group was higher than that of control group at postoperative 24 hr. Activated partial thromboplastin time in aprotinin group was longer than that of control group at intensive care unit (ICU). Troponin-I level and postoperative blood loss volumes in aprotinin group were lower than those of control group at ICU. There were no significant differences between the two groups on the others. These results showed that low dosage of only priming solution during cardiac surgery with CPB reduced platelet destruction and postoperative bleeding, and attenuates myocardial damage. However, further studies need to be carried out with more population or pediatric patients for evaluating various aprotinin usage.

• Applied Biological Chemistry
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• v.43 no.1
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• pp.24-28
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• 2000

This study was conducted to evaluate the effect of ultrafiltration (UF) process variables on permeate flux and membrane resistance and to clarify apple vinegar for quality improvement. Apple vinegar was clarified in a laboratory ultrafiltration system with hollow fiber membrane made of polysulfone and MWCO 30,000 and 10,000. The permeate flux increased with the increase of flow rate and the optimum pressure was $1.5\;kgf/cm^2$ in this system. The turbidity of clarified apple vinegar treated UF largely decreased. pH and acidity of treated samples showed the same level as those of untreated apple vinegar. The permeate flux continuously declined while the fouling material accumulated on the membrane as the operation time increased. Resistance decreased with lower pressure, which could be explained by expansion of pore size at lower pressure and minor compaction of the polarized layer at lower pressure.

• Journal of Preventive Medicine and Public Health
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• v.37 no.4
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• pp.381-389
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• 2004

Objective : To compare the efficacy between SKI306X and Diclofenac by using generalized estimating equations (GEE) methodology in the analysis of correlated bivariate binary outcome data in Osteoarthritis (OA) diseases. Methods : A randomized, double-blind, active comparator-controlled, non-inferiority clinical trial was conducted at 5 institutions in Korea with the random assignment of 248 patients aged 35 to 75 years old with OA of the knee and clinical evidence of OA. Patients were enrolled in this study if they had at least moderate pain in the affected knee joint and a score larger than 35mm as assessed by VAS (Visual Analog Scale). The main exposure variable was treatment (SKI 306X vs. Diclofenac) and other covariates were age, sex, BMI, baseline VAS, center, operation history (Yes/No), NSAIDS (Y/N), acupuncture (Y/N), herbal medicine (Y/N), past history of musculoskeletal disease (Y/N), and previous therapy related with OA (Y/N). The main study outcome was the change of VAS pain scores from baseline to the 2nd and 4th weeks after treatment. Pain scores were obtained as baseline, 2nd and 4th weeks after treatment. We applied GEE approach with empirical covariance matrix and independent(or exchangeable) working correlation matrix to evaluate the relation of several risk factors to the change of VAS pain scores with correlated binary bivariate outcomes. Results : While baseline VAS, age, and acupuncture variables had protective effects for reducing the OA pain, its treatment (Joins/Diclofenac) was not statistically significant through GEE methodology (ITT:aOR=1.37, 95% CI=(0.8200, 2.26), PP:aOR=1.47, 95% CI=(0.73, 2.95)). The goodness-of-fit statistic for GEE (6.55, p=0.68) was computed to assess the adequacy of the fitted final model. Conclusions : Both ANCOVA and GEE methods yielded non statistical significance in the evaluation of non-inferiority of the efficacy between SKI306X and Diclofenac. While VAS outcome for each visit was applied in GEE, only VAS outcome for the fourth visit was applied in ANCOVA. So the GEE methodology is more accurate for the analysis of correlated outcomes.

• Health Policy and Management
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• v.29 no.4
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• pp.482-495
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• 2019

Background: An important function of the regional public hospital is to satisfy the basic medical needs of the community through the stable provision of high-quality medical services. The purpose of this study was to identify the relevance index (RI) of the regional public hospital and to identify the factors that affect the RI. Methods: Data were obtained from the 2017 regional public hospital operation evaluation report and 2017 medical monitoring report for vulnerable area. RI of the regional public hospital was a dependent variable, and multiple regression analysis was performed with observed variables of medical supply-demand condition, medical supply, and medical supply structure. Direct effects and indirect effects were confirmed by the analysis of structural equation models (SEM) to see if there were mediating effects. Results: The RI was 13.1%, and the average of all percentage refined diagnosis-related group (RDRG) was 29.4%. Factors affecting RI were medical supply-demand conditions, medical supply, and medical supply structure. As a result of multiple regression analysis, RI was higher when high percentage RDRG of the regional public hospital (t=4.117, p<0.05), the size of regional public hospital location (t=-2.554, p<0.05), and the population of regional public hospital location (t =-2.415, p<0.05) were smaller. The results of the SEM analysis show that the higher the medical supply-demand conditions, the more direct effect of decreasing the RI and the indirect effect of decreasing the effect of reduction through the medical supply (direct effect=-1.322, total effect=-0.573, p<0.01). The higher the medical supply structure, the more direct effect on the RI (direct effect=1.047, p<0.05) and the higher the medical supply, the more indirect effect of RI through the medical supply structure (total effect=direct effect=0.619, p<0.05). Conclusion: It has been confirmed that the provision of medical services can affect the RI the regional public hospital which should be considered in carrying out future policies.

• The Journal of the Korea Contents Association
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• v.12 no.9
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• pp.357-368
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• 2012

The purpose of this study is to empirically examine the impact of enterprise R&D investment on international trade in Korea under the new Normal Era. In order to test whether the time series data of trade variables are stationary or not, we put in operation unit root test and cointegration test. Based on VECM (Vector Error Correction Model), we also apply impulse response functions and variance decomposition to estimate the dynamic effects in the short-run and long-run. The results show that the relationship between enterprise R&D investment and international trade (export and import) exists in the long-run as well as in the short-run. The results of applying impulse response functions and variance decomposition also indicate that the impact of enterprise R&D investment on international trade is positive, and a significant portion of fluctuations in the trade variable is explained by enterprise R&D investment. Therefore, enterprise R&D investment must be continuously increased to improve economic growth with promoting trading competition power in Korea under the new Normal Era.