• International Journal of Computer Science & Network Security
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• v.23 no.9
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• pp.37-46
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• 2023

The main aim of the article is to solve the problem of automating price monitoring using marketing forecasting methods and Excel functionality under martial law. The study used the method of algorithms, trend analysis, correlation and regression analysis, ANOVA, extrapolation, index method, etc. The importance of monitoring consumer price developments in market pricing at the macro and micro levels is proved. The introduction of a Dummy variable to account for the influence of martial law in market pricing is proposed, both in linear multiple regression modelling and in forecasting the components of the Consumer Price Index. Experimentally, the high reliability of forecasting based on a five-factor linear regression model with a Dummy variable was proved in comparison with a linear trend equation and a four-factor linear regression model. Pessimistic, realistic and optimistic scenarios were developed for forecasting the Consumer Price Index for the situation of the end of the Russian-Ukrainian war until the end of 2023 and separately until the end of 2024.

• Nuclear Engineering and Technology
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• v.56 no.10
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• pp.4307-4326
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• 2024

This study investigates Equivalent Spherical Diameter (ESD) estimation at high inlet velocity pool scrubbing conditions using the Interfacial Area Transport Equation (IATE) diameter model including bubble-induced turbulence and interphase modeling. The compatibility of area-averaged Sauter Mean Diameter (SMD), areaaveraged Local Equivalent Diameter (LED) and void-weighted area-averaged LED approaches to estimate the ESD are explored and the proposed model is validated against available experimental data. The study reveals that the prevalent constant ESD assumption in pool scrubbing codes is not universal by showcasing a decreasing trend along the column due to intensive bubble breakup. The area-averaged LED approach fails to capture this trend, while the area-averaged SMD and void-weighted area-averaged LED approaches provide accurate estimations aligned with experimental data. Turbulence parameters, interfacial forces, and diameter modeling are identified as crucial for accurate predictions of flow and geometrical variables by setting up the OpenFOAM framework. A sensitivity analysis indicates that the inlet velocity has an acceptable effect on the ESD along the column. The ESD increases near the exit and decreases in the swarm region by increasing the inlet velocities. Turbulent intensity reduces ESD across all column sections while changes in aspect ratio minimally impact ESD. The study shows promise in developing correlations that take into account the spatial variation of ESD in pool scrubbing conditions.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.6
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• pp.4067-4076
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• 2015

This study aims to examine the trend in household catastrophic medical expenditure according to the healthcare coverage types and its associated factors based on the raw data of the Korean Health Panel over the years 2008 to 2011. Correspondence analysis was used to investigate the trend in the incidence rates of annual catastrophic medical expenditure and generalized estimating equation to examine the factors influencing the incidence of catastrophic medical expenditure. The annual mean incidence rates of household catastrophic medical expenditure were 25.1%, 15.4%, 10.1%, 5.4% and 3.2% in the threshold levels of 10%, 15%, 20%, 30%, and 40% respectively. The incidence rate of household catastrophic medical expenditure was higher when the total annual household income was lower, the education level of the householder was lower, the healthcare coverage type was National Health Insurance, the householder had disability, the age of the householder was older, the number of household members was smaller, the subjective health status of household members was lower, and the prevalence rate of the chronic disease of the household was higher(p<0.05). Therefore, a policy for vulnerable households with older or patient members of chronic diseases should be established.

• Journal of Korean Tunnelling and Underground Space Association
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• v.23 no.4
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• pp.221-232
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• 2021

Most of measurement sensors used for maintenance are continuously exposed to various environmental factors such as transportation and rainfall, so the possibility of breakage increases gradually. The maintenance measurement sensor of domestic subway tunnel shows an average of 14.2% to 14.8% of loss rate after about 5 to 6 years from installation, and it shows a sensor loss rate of about 13.9% in case of foreign countries. As a result, it can be seen that an average of 15% of maintenance measurement sensors at home and abroad cannot send measuring values after 5~6 years. In order to continuously collect accurate data, measurement data must be recovered by performing repair or replacement of the sensor, but some lost measurement sensors are buried after installation. So, there are many difficulties in repairing sensors, including cost and time. Therefore, in this paper, we propose lost measurement sensor data estimation technology based on data trend analysis using adjacent sensors.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.16 no.6
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• pp.522-529
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• 2004

In this study, external condensation heat transfer coefficients (HTCs) of flammable refrigerants of propylene, propane, isobutane, butane, DME, and HFC32 were measured on a horizontal plain tube, 26 fpi low fin tube, and Turbo-C tube. All data were taken at the temperature of 39$^{\circ}C$ with a wall subcooling of 3∼8$^{\circ}C$. Test results showed a typical trend that condensation HTCs of flammable refrigerants decrease with increasing wall subcooling. HFC32 had the highest HTCs among the tested refrigerants showing 44% higher HTCs than those of HCFC22 while DME showed 28% higher HTCs than those of HCFC22. HTCs of propylene and butane were similar to those of HCFC22 while those of propane and isobutane were similar to those of HFC134a. Based upon the tested data, Nusselt's equation is modified to predict the plain tube data within a deviation of 3%. For 26 fpi low fin tube, Beatty and Katz equation predicted the data within a deviation of 7.3% for all flammable refrigerants tested. The heat transfer enhancement factors for the 26 fpi low fin and Turbo-C tubes were 4.6∼5.7 and 4.7∼6.9 respectively for the refrigerants tested indicating that the performance of Turbo-C tube is the best among the tubes tested.

• Atmosphere
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• v.17 no.3
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• pp.291-298
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• 2007

The precipitable water vapors (PWVs) obtained from Global Positioning System (GPS) and Microwave Radiometer (MWR) measurements have been compared for validation of precision of the GPS PWV at Daegwallyoung station for 21 days from Sep. 30 to Oct. 20, 2006. The GPS PWV is estimated using the delay of GPS signals due to the water vapor in the atmosphere with a local mean temperature equation, called HP model, and the MWR PWV by the combinational radiance observation of two channels (23.8 and 31.4 GHz). During the co-observation period, the MWR and GPS PWV show a similar trend, and the bias between the PWVs is 1.7 mm on average. When the bias is removed, the PWV of GPS gives good agreement with that of MWR, having about 1 mm for both the standard deviation and RMS error between the GPS and MWR PWV.

• Transactions of the Korean Society of Automotive Engineers
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• v.10 no.4
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• pp.223-233
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• 2002

The air distribution duct with multiple outlets is an essential part of automotive air-conditioning system In a bus. The estimation of airflow rate in an automotive air-conditioning duct is typically very complicate due to large variations in cross-sectional area and abrupt changes in flow direction, as well as unbalanced distribution of the flow. In this paper, the flow characteristic in a duct with multiple outlets is investigated through experiment, CFD simulation and a one-dimensional simulation. Numerical simulations have been performed for two simplified air conditioning ducts with multiple outlets used in a medium bus. The three dimensional Navier-Stokes code was used to evaluate the overall pressure, velocity Held, and distribution rate at each diffuser according to the change of various design parameters such as ratio of cross-sectional area and radius of bifurcated region. In addition, a one-dimensional program based on Bernoulli equation was developed to obtain optimized diffuser area required to equalize discharge flow rate at each outlet. As a result of this study, optimized diffuser area of design variable by one-dimensional program was very reasonable as compared to the trend deduced from CFD Simulation. Therefore, the simple and convenient one-dimensional analysis developed in this study can be applied in practical design procedure for air-conditioning duct.

• Structural Engineering and Mechanics
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• v.40 no.4
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• pp.563-581
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• 2011

Many novel materials, developed in recent years, have obvious properties with different modulus of elasticity in tension and compression. The ratio of their tensile modulus to compressive modulus is as high as five times. Nowadays, it has become a new trend to study the mechanical properties of these bimodular materials. At the present stage, there are extensive studies related to the strength analysis of bimodular structures, but the investigation of the buckling stability problem of bimodular rods seems to cover new ground. In this article, a semi-analytical method is proposed to acquire the buckling critical load of bimodular slender rod. By introducing non-dimensional parameters, the position of neutral axis of the bimodular rod in the critical state can be determined. Then by combining the phased integration method, the deflection differential equation of bimodular pin-ended slender rod is deduced. In addition, the buckling critical load is obtained by solving this equation. An example, which is conducted by comparing the calculation results between the three of the methods including the laboratory tests, numerical simulation method and the method we developed here, shows that the method proposed in the present work is reliable to use. Furthermore, the influence of bimodular characteristics on the stability is discussed and analyzed.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.03a
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• pp.198-207
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• 2010

Many methods and techniques have been developed to obtain the accurate design parameters in soft soils. In particular, several researchers suggest the techniques to get the void ratio for understanding the soil behavior. The objective of this paper verifies the accuracy of the proposed analytical solution for determining the void ratio based on the elastic wave velocities. The paper covers the theories of Wood, Biot, Gassmann and Foti proposed chronological order. The total theory represents the wave propagation in fully saturated medium. To verify the proposed analytical solution, the laboratory and field tests are carried out. After measuring the elastic wave, the void ratios are assessed using proposed equation. The volume based void ratios are also obtained for comparing with the estimated value by several equations. The values estimated by volume, Gassmann and Biot are show good similarity. However, the void ratios based on Wood and Foti methods have a slightly different trend. This study suggests that the theories of Biot and Gassmann may be a useful equation for assessing the void ratio using elastic wave velocities in the field.

• Journal of the Korean School Mathematics Society
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• v.2 no.1
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• pp.231-242
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• 1999

The focus of this development program is to input multimedia materials into learning according to the trend of recent social changes and to maximize the learning effect for improving problem-solving by offering familiar teaching materials. The expecting effects of this study are as follows: 1. This program helps students acquire mathematical concepts and principles about circular equation through concrete examples using a variety of media - text, voice, sound, and animation and so on - , makes it possible individual learning which was difficult for students to expect at the existing multitude class as progressing learning each unit on the screen and the perfect learning by offering FEED BACK 2. This program varied the difficulty of learning contents to learn according to learning abilities of learners by using animation and making the most of merits of computer and was able to improve learning effect by studying in a mutual way with managing learning procedure nonsuccessively. 3. Class using CAI program about developed circular equation unit has a positive effect on improving problem-solving by becoming from teacher centered class to student centered one. 4. This program makes students understand the contents of auxiliary learning in multimedia computer more efficiently, and cultivate abilities to adopt in accordance with changes in the future society by forming familiar computer mind.