• International Journal of Air-Conditioning and Refrigeration
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• v.14 no.3
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• pp.118-123
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• 2006

A few commonly used correlation equations of the enthalpy of vaporization essential to the analysis of refrigeration cycles are reviewed. A new four-parameter correlation equation is proposed assuming that the enthalpy of vaporization could be represented with a linear form of the temperature and an additional function which slowly decreases as the temperature increases. It is not a common practice to measure the enthalpy of vaporization by experiment; therefore, performance of the new correlation is examined using numeric data from the ASHRAE tables for 22 pure substance refrigerants. The new correlation equation and other existing ones are fitted to the data optimizing the root mean squared deviation. All data points are weighted equally and NBP (normal boiling point) is used as a fixed point since the NBP is important for refrigeration application. The new four-parameter equation yields an average absolute deviation of 0.05% for 22 refrigerants which is smaller than those of other four-parameter equations, such as Guermouche-Vergnaud (0.08%), Aerebrot (0.13%), Radoz-Lyderson (0.08%), and Somayajulu four-parameter equation (0.08%).

• Journal of the Korean Society of Physical Medicine
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• v.13 no.4
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• pp.19-25
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• 2018

PURPOSE: This study was conducted to investigate the correlation between the activity of suprahyoid muscles, infrahyoid muscles and swallowing ability in stroke patients with dysphagia. METHODS: The subjects of this study were 120 patients who were diagnosed with CT or MRI stroke and had swallowing disorder at Daegu Metropolitan General Hospital from August 2014 to February 2017. The suprahyoid and infrahyoid muscle activity was measured in patients with dysphagia and the new videofluoroscopy swallowing studies scale (new VFSS scale) was used for evaluation of swallowing function. Correlation analysis was conducted using the measured data. RESULTS: The activities of suprahyoid muscles were 325.8 (%RVC) on average, while the average infrahyoid muscle activity was 302.65 (%RVC) and the average value of the new VFSS scale was 31.52. The total for oral organs was 3.62 on average and that for pharynx organs was 28.30 on average. The activity of the suprahyoid muscles showed a significant positive correlation with the activity of the infrahyoid muscles, but a significant negative correlation with the total oral phase, total pharyngeal phase and total new VFSS scale (p<.01). The activity of the infrahyoid muscles showed a significant negative correlation with the total oral phase, total pharyngeal phase, and total new VFSS (p<.01). CONCLUSION: Based on the results of this study, it is necessary for researchers to consider the infrahyoid and suprahyoid muscles when conducting swallowing rehabilitation.

• Nuclear Engineering and Technology
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• v.47 no.1
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• pp.135-138
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• 2015

A new correlation predicting the idealized critical mass-flow rates of water for subcooled and saturated liquid water including two-phase water flow was developed for a wide range of upstream stagnation pressures (e.g., 0.5-20.0 MPa). A choking correction factor dependent on the upstream stagnation pressure and subcooled temperature was introduced into a new correlation, and its values were suggested to satisfy the idealized nozzle data within 10% error ranges. The suggested correlation will be instructive and helpful for related studies and/or engineering works.

• Nuclear Engineering and Technology
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• v.54 no.3
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• pp.867-876
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• 2022

An experimental study has been conducted to investigate the heat transfer characteristics of supercritical carbon dioxide (sCO₂) uniformly heated in the horizontal circular smooth tube. The results illustrated that there was a significant difference in heat transfer between the top wall and bottom wall due to the buoyancy. Bulk flow acceleration cannot be negligible in the high heat flux region, which leads to heat transfer deterioration. A new heat transfer correlation is proposed, in which the buoyancy parameter and bulk flow acceleration have been taken into account. The new correlation and six classic correlations for sCO₂ are examined in horizontal tubes. The comparison indicates that the new correlation has a better performance for sCO₂ flowing through a horizontal heating tube under natural circulation conditions. For example, 94.9% of the calculated results using the new heat transfer correlation were within ±30% of the experimental results while only 87.9% of that using the Jackson correlation (the best of the six) were within the same error bands.

• Journal of Korean society of Dental Hygiene
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• v.23 no.4
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• pp.251-260
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• 2023

Objectives: This study aimed to provide basic data for the development of clinical practice-related education program by analyzing the effects of grit, job satisfaction, and retention intention on transition shock of new dental hygienists. Methods: From April 19 to July 4, 2022, the data was collected from 200 new dental hygienists working for dental hospitals/clinics. Using the SPSS Statistics ver. 22.0, this study was conducted the t-test, one-way ANOVA, Pearson's correlation analysis, and multiple regression analysis. Results: There were positive correlations between grit, job satisfaction, and retention intention, a negative correlation between grit and transition shock, a positive correlation between job satisfaction and retention intention, a negative correlation between job satisfaction and transition shock. and a negative correlation between retention intention and transition shock. As the factors affecting transition shock, lower pay and main performance of medical cooperation work increased transition shock. When job satisfaction and retention intention were higher, transition shock decreased. Conclusions: In order to reduce transition shock of new dental hygienists, it would be necessary to operate clinical practice-related training program, and also to establish a training environment similar to the clinical site/context/situation similar to clinical context/situation.

• Bulletin of the Korean Chemical Society
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• v.17 no.4
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• pp.347-348
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• 1996

A set of substituent constants, σc+, has been widely used comparing the stability of carbocation in super acid condition. Plotting of 13C chemical shifts of cationic carbon (Δδc+) against σc+ constants yields an excellent correlation with a good correlation coefficient (r=0.999) for a cyclopentyl cation system. But these σc+ constants show poor linearity in norbornenyl cations that well known to show homoallylic stabilization in a cationic condition. We calculated the new substituent constant, σc+π, and found that the new substituent constants give an excellent correlation in π- and πσ-participating cation systems.

• Journal of information and communication convergence engineering
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• v.13 no.2
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• pp.105-112
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• 2015

The estimation of missing sensor values is an important problem in sensor network applications, but the existing approaches have some limitations, such as the limitations of application scope and estimation accuracy. Therefore, in this paper, we propose a new estimation model based on a spatial-temporal correlation analysis (STCAM). STCAM can make full use of spatial and temporal correlations and can recognize whether the sensor parameters have a spatial correlation or a temporal correlation, and whether the missing sensor data are continuous. According to the recognition results, STCAM can choose one of the most suitable algorithms from among linear interpolation algorithm of temporal correlation analysis (TCA-LI), multiple regression algorithm of temporal correlation analysis (TCA-MR), spatial correlation analysis (SCA), spatial-temporal correlation analysis (STCA) to estimate the missing sensor data. STCAM was evaluated over Intel lab dataset and a traffic dataset, and the simulation experiment results show that STCAM has good estimation accuracy.

• Geomechanics and Engineering
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• v.28 no.4
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• pp.397-404
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• 2022

Accurate prediction of the undrained shaft resistance is essential for robust design of bored piles in undrained condition. The undrained shaft resistance is calculated using the undrained adhesion factor multiplied by the undrained cohesion of the soil. However, the available correlations to predict the undrained adhesion factor have been developed using simple regression techniques and the accuracy of these correlations has not been thoroughly assessed in previous studies. The lack of the assessment of these correlations made it difficult for geotechnical engineers to select the most accurate correlation in routine designs. Furthermore, limited attempts have been made in previous studies to use advanced data mining techniques to develop simple and accurate correlation to predict the undrained adhesion factor. This research, therefore, has been conducted to fill these gaps in knowledge by developing novel and robust correlation to predict the undrained adhesion factor. The development of the new correlation has been conducted using the multi-objective evolutionary polynomial regression analysis. The new correlation outperformed the available empirical correlations, where the new correlation scored lower mean absolute error, mean square error, root mean square error and standard deviation of measured to predicted adhesion factor, and higher mean, a20-index and coefficient of correlation. The correlation also successfully showed the influence of the undrained cohesion and the effective stress on the adhesion factor. Hence, the new correlation enhances the design accuracy and can be used by practitioner geotechnical engineers to ensure optimized designs of bored piles in undrained conditions.

• Nuclear Engineering and Technology
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• v.54 no.10
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• pp.3962-3973
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• 2022

Several critical heat flux (CHF) correlations including the look-up table in the MARS code have been assessed for the prediction of CHF in a downward-flow narrow rectangular channel. For the assessment, we built an experiment database that covers pressures between 1.01 and 39.0 bar, gap sizes between 1.09 and 6.53 mm, mass fluxes up to 25,772 kg/m²s, and under one-sided and two-sided heating conditions. The results of the assessment showed that the Kaminaga correlation has the best overall prediction compared to others. However, because the correlation uses global variables, such as inlet and outlet subcooling and total heat transfer area, it is difficult to use in a system code. A new CHF correlation is then proposed by replacing the global variables in the Kaminaga correlation with local ones and adding correction factors to consider the effect of gap size, mass flux, and the number of heating walls. Additional correction factor is added to consider the effect of inlet subcooling. It is shown that the new one is better than the Kaminaga correlation and it is easy to implement to any system code.

• Journal of Environmental Science International
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• v.2 no.3
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• pp.207-216
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• 1993

The concentrations of $SO_2$ and $SO_3$ were measured to estimate a new developed long time exposure $SO_2$ sampler at Onsan industrial area considering the meteorological factors from June to October, 1992. The mean concentration of $SO_3$ by $PbO_2$ method was 0.924 mg $SO_3 / 10cm^2$ $PbO_2$/day and their high values were shown in the center of the industrial area, which show potential pollution due to the increase of industrial activities and micrometeorological factors in and around the sites. As a result of statistical correlation between $SO_2$ concentration by new sampling method and $SO_3$ concentration by $PbO_2$ method in July and August, 1992, correlation coefficients were high (r=0.87, 0.91) and shown more than 0.83 value in the high concentration data set, which was arbitrarily divided into 7~10${\mu}l$$SO_2$ concentration in an attempt to further investigate these relationships. Therefore, use of new developed long time exposure TEX>$SO_2$ sampler is good for TEX>$SO_2$ measurement and valuable for estimation of air quality in the urban and industrial area. Key Words : a new developed long time exposure TEX>$SO_2$ sampler, correlation coefficients, high, $SO_2$ measurement, estimation of air Quality.