• Tuberculosis and Respiratory Diseases
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• v.85 no.4
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• pp.349-357
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• 2022

Background: The most consistently identified mortality determinants for the new coronavirus 2019 (COVID-19) infection are aging, male sex, cardiovascular/respiratory diseases, and cancer. They were determined from heterogeneous cohorts that included patients with different disease severity and previous conditions. The main goal of this study was to determine if activities of daily living (ADL) dependence measured by Barthel's index could be a predictor for COVID-19 mortality. Methods: A prospective cohort study was performed with a consecutive sample of 340 COVID-19 patients representing patients from all over the northern region of Portugal from October 2020 to March 2021. Mortality risk factors were determined after controlling for demographics, ADL dependence, admission time, comorbidities, clinical manifestations, and delay-time for diagnosis. Central tendency measures were used to analyze continuous variables and absolute numbers (proportions) for categorical variables. For univariable analysis, we used t test, chi-square test, or Fisher exact test as appropriate (α=0.05). Multivariable analysis was performed using logistic regression. IBM SPSS version 27 statistical software was used for data analysis. Results: The cohort included 340 patients (55.3% females) with a mean age of 80.6±11.0 years. The mortality rate was 19.7%. Univariate analysis revealed that aging, ADL dependence, pneumonia, and dementia were associated with mortality and that dyslipidemia and obesity were associated with survival. In multivariable analysis, dyslipidemia (odds ratio [OR], 0.35; 95% confidence interval [CI], 0.17-0.71) was independently associated with survival. Age ≥86 years (pooled OR, 2.239; 95% CI, 1.100-4.559), pneumonia (pooled OR, 3.00; 95% CI, 1.362-6.606), and ADL dependence (pooled OR, 6.296; 95% CI, 1.795-22.088) were significantly related to mortality (receiver operating characteristic area under the curve, 82.1%; p<0.001). Conclusion: ADL dependence, aging, and pneumonia are three main predictors for COVID-19 mortality in an elderly population.

• Journal of Energy Engineering
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• v.25 no.1
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• pp.48-55
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• 2016

The autoignition temperature (AIT) of a material is the lowest temperature at which the material will spontaneously ignite. The AIT is important index for the safe handling of flammable liquids which constitute the solvent mixtures. This study measured the AITs of n-hexanol+p-xylene system by using ASTM E659 apparatus. The AITs of n-hexanol and p-xylene system which constituted binary system were $275^{\circ}C$ and $557^{\circ}C$, respectively. The experimental AITs of n-hexanol+p-xylene system system were a good agreement with the calculated AITs by the proposed equations with a few A.A.D.(average absolute deviation).

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2008.04a
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• pp.387-390
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• 2008

The importance of the life cycle cost analysis for construction projects of bridge has been recognized over the last decades. Accordingly, theoretical models, guidelines, and supporting softwares have been developed for the life cycle cost analysis of bridges. However, it is difficult to predict life cycle cost considering uncertainties precisely. This paper presents methodology for optimal design of substructure for a steel box bridge. Total life cycle cost for the service life is calculated as sum of initial cost, damage cost considering uncertainty, maintenance cost, repair and rehabilitation cost. The optimization method is applied to design of a bridge substructure with minimal cost, in which the objective function is set to life cycle cost and constraints are formulated on the basis of Korean Bridge Design Specification. Initial cost is calculated based on standard costs of the Korea Construction Price Index and damage cost on the damage probabilities to consider the uncertainty of load and resistance. An advanced first-order second moment method is used as a practical tool for reliability analysis using damage probability. Maintenance cost and cycle is determined by a stochastic method and user cost includes traffic operation costs and time delay costs.

• Journal of the Korean Institute of Gas
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• v.20 no.5
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• pp.1-8
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• 2016

The autoignition temperature (AIT) of a substance is the lowest temperature at which the vapor ignites spontaneously from the heat of the environment. The AIT is important index for the safe handling of flammable liquids which constitute the solvent mixtures in the process. This study measured the AITs of n-butanol+p-xylene mixture by using ASTM E659 apparatus. The AITs of n-butanol and p-xylene which constituted binary system were $340^{\circ}C$ and $557^{\circ}C$, respectively. The experimental AITs of n-butanol+p-xylene mixture were a good agreement with the calculated AITs by the proposed equations with a few A.A.D.(average absolute deviation).

• Fire Science and Engineering
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• v.28 no.4
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• pp.44-49
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• 2014

The autoignition temperaturs (AIT) of solvent mixture is important index for the safe handling of flammable liquids which constitute the solvent mixtures. This study measured the AIT and ignition delay time for Propionic acid and 3-Hexanone system by using ASTM E659 apparatus. The AITs of Propionic acid and 3-Hexanone which constituted binary system were $511^{\circ}C$ and $425^{\circ}C$, respectively. The experimental AIT of Propionic acid and 3-Hexanone system were a good agreement with the calculated AIT by the proposed equations with a few average absolute deviation (A.A.D.). And Propionic acid and 3-Hexanone system was shown the minimum autoignition temperature behavior (MAITB).

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.11a
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• pp.661-665
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• 2006

This study investigates objective and subjective evaluations of refrigerator noise. To describe the fluctuations like a click, a rapid increase of sound level, a change of pitch, a transition into the stationary and ending phase, the psychoacoustical and autocorrelation function(ACF) parameters have been employed. First, subjective evaluation of the noisiness of 24 kinds of refrigerators was conducted. Then, the relationship between objective measures of the refrigerator noise on perceived noisiness was examined with multiple regression analyses. Sound Quality Indices using the psychoacoustical and ACF parameters were also developed. The important psychoacoustical parameters for evaluating noisiness are loudness and roughness of stationary phase. The relationship between the noisiness and the ACF parameters shows that sound energy ${\Phi}(0)$ and its fluctuations are important. Also, refrigerator sounds that had a fluctuation of pitch were rated as more annoying. The fluctuation of pitch is expressed by ${\tau}_1\;and\;{\Phi}_1$ defined by the delay time and the amplitude of the first peak of the ACF.

• Journal of the Korean Operations Research and Management Science Society
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• v.23 no.4
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• pp.213-224
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• 1998

Since the late 1980s, an Increasing number of neural network models have been studied in the areas of financial prediction and analysis. The purpose of this study is to Investigate the possibility of building a neural network model that is able to construct a profitable trading strategy in the Korean Stock Market. This study classifies stocks into the future market winners and losers from the publicly available accounting information and builds portfolios based on this information. The performances of the winner portfolios and the loser portfolios are compared with each other and against the market index. The empirical result of this research is consistent with the traditional fundamental analysis where it is claimed that the financial statements contain firm values that may not be fully reflected In stock prices without delay. Despite the supporting empirical evidence. It is somewhat Inconclusive as to whether or not the abnormal return in excess of market return is the result of the extra knowledge obtained in the neural network models derived from the historical accounting data. This research attempts to open another avenue using neural network models for searching for evidence against market efficiency where statistics and intuition have played a major role.

• The Bulletin of The Korean Astronomical Society
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• v.41 no.2
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• pp.41.2-41.2
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• 2016

We perform three statistical studies on the physical properties and oscillations in the confined plasma such as a photospheric sunspot and confined coronal loop. From the statistical studies on the sunspot umbra and its oscillation, we find that (1) the total magnetic flux inside the umbra for the three groups increases proportionally with the powers of the umbral area and the power indices in the three groups significantly differ from each other; (2) the three groups have different characteristics in their umbral area, intensity, magnetic field strength, and Doppler velocity as well as their relationships; (3) the mean frequency of the umbral oscillations increases with the umbral mean magnetic field strength and height; (4) the time delay of the core intensity of Fe I absorption line relative to the continuum which are de-convolved with the frequency range higher than 3.5 mHz is mostly positive, implying that the photospheric umbral oscillations are likely upwardly propagating; (5) the umbral mean plasma beta ranges approximately 0.6-1.1 and does not vary significantly from pores to mature sunspots. From the comparative study on the quasi-periodic pulsations (QPPs) in the solar and stellar flares, (6) we find that the power index of the periods scaling the damping times observed in the stellar QPPs is consistent with that observed in the solar QPPs, suggesting that physical mechanisms responsible for the stellar QPPs are likely the magneto-hydrodynamic oscillation of solar coronal loops.

• Korean Chemical Engineering Research
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• v.52 no.2
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• pp.256-260
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• 2014

Interior of the building is used as a MDF plywood if there is a fire in order to delay the ignition, flame retardant paint, flame retardant solution and flame retardant film are being handled by the flame retardant. Combustion characteristics anf flame retardant performance results can be summarized as follows: General film with a sample showed that short of the criteria in terms of carbonation area, and the results of flame retardant paint, flame retardant solution and flame retardant film products satisfied the criteria. Toxic gases generated in the combustion process results in a film samples using a high incidence of carbon monoxide and the creation of a smoke could be seen. This confirm that is estimated that result from incomplete combustion of PVC film that attach, and displays high toxicity index and hazard class relatively.

• Information and Communications Magazine
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• v.4 no.4
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• pp.505-524
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• 1987

Nowaday all the countries of the world have studied the various problems caused in operating their own ports efficiently. Ship delay in the port is attributal to the inefficient operation in the navigation aids, the cargo handling, the storage and transfer facilities, and to the inefficient allocation of gangs or to a bad service for ships. Among these elements the allocation of gangs is the predominating factor in minimizing ship's turn round time. At present, in the case of Pusan Port. the labour union and stevedoring companies allocate gangs in every hatches of ships by a rule of thumb, just placing emphasis on minimizing ship's turn round time, without applying the principle of allocation during the cargo handling. Owing to this the efficiency of the cargo handling could not be expected to be maximized and this unsystematic operation result in supplying human resources of much unnecessary surplus gangs. Therefore in this paper the optimal size and allocation of gangs for minimizing the ship's turn round time is studied and formularized. For the determination of the priority for allocation the evaluation function, namely $F=PHi^{n}{\times}(W+H)$, can be obtained; where, PHI : Principal Hatch Index W : Total Cargo Weight represented in Gang-Shifts H : Total Number of Ship's hatches and also for the optimal size of gangs the average number of gang allocated per shift (Ng), namely Ng=W/PHI, is used. The proposed algorithm is applied to Pusan Port and its validity is verified.