• Korean Journal of Exercise Nutrition
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• v.25 no.1
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• pp.23-29
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• 2021

[Purpose] This preliminary study aimed to develop a regression model to estimate the non-exercise activity thermogenesis (NEAT) of Korean adults using various easy-to-measure dependent variables. [Methods] NEAT was measured in 71 healthy adults (male n = 29; female n = 42). Statistical analysis was performed to develop a NEAT estimation regression model using the stepwise regression method. [Results] We confirmed that age^A, weight^B, heart rate (HR)_average^C, weight × HR_average^D, weight × HR_sum^E, systolic blood pressure (SBP) × HR_rest^F, fat mass ÷ height^2G, gender × HR_average^H, and gender × weight × HR_sum^I were important variables in various NEAT activity regression models. There was no significant difference between the measured NEAT values obtained using a metabolic gas analyzer and the predicted NEAT. [Conclusion] This preliminary study developed a regression model to estimate the NEAT in healthy Korean adults. The regression model was as follows: sitting = 1.431 - 0.013 × (A) + 0.00014 × (D) - 0.00005 × (F) + 0.006 × (H); leg jiggling = 1.102 - 0.011 × (A) + 0.013 × (B) + 0.005 × (H); standing = 1.713 - 0.013 × (A) + 0.0000017 × (I); 4.5 km/h walking = 0.864 + 0.035 × (B) + 0.0000041 × (E); 6.0 km/h walking = 4.029 - 0.024 × (C) + 0.00071 × (D); climbing up 1 stair = 1.308 - 0.016 × (A) + 0.00035 × (D) - 0.000085 × (F) - 0.098 × (G); and climbing up 2 stairs = 1.442 - 0.023 × (A) - 0.000093 × (F) - 0.121 × (G) + 0.0000624 × (E).

• Korean Journal of Exercise Nutrition
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• v.25 no.1
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• pp.35-41
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• 2021

[Purpose] This pilot study aimed to develop a regression model to estimate the excess post-exercise oxygen consumption (EPOC) of Korean adults using various easy-to-measure dependent variables. [Methods] The EPOC and dependent variables for its estimation (e.g., sex, age, height, weight, body mass index, fat-free mass [FFM], fat mass, % body fat, and heart rate_sum [HR_sum]) were measured in 75 healthy adults (31 males, 44 females). Statistical analysis was performed to develop an EPOC estimation regression model using the stepwise regression method. [Results] We confirmed that FFM and HR_sum were important variables in the EPOC regression models of various exercise types. The explanatory power and standard errors of estimates (SEE) for EPOC of each exercise type were as follows: the continuous exercise (CEx) regression model was 86.3% (R²) and 85.9% (adjusted R²), and the mean SEE was 11.73 kcal, interval exercise (IEx) regression model was 83.1% (R²) and 82.6% (adjusted R²), while the mean SEE was 13.68 kcal, and the accumulation of short-duration exercise (AEx) regression models was 91.3% (R²) and 91.0% (adjusted R²), while the mean SEE was 27.71 kcal. There was no significant difference between the measured EPOC using a metabolic gas analyzer and the predicted EPOC for each exercise type. [Conclusion] This pilot study developed a regression model to estimate EPOC in healthy Korean adults. The regression model was as follows: CEx = -37.128 + 1.003 × (FFM) + 0.016 × (HR_sum), IEx = -49.265 + 1.442 × (FFM) + 0.013 × (HR_sum), and AEx = -100.942 + 2.209 × (FFM) + 0.020 × (HR_sum).

• Journal of Korea Water Resources Association
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• v.54 no.11
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• pp.863-873
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• 2021

The mechanical dispersion which dominates solute transport in porous media is caused by the difference in flow velocity within pores. Longitudinal dispersion coefficient and longitudinal dispersivity that are hydro-dispersive parameters of advection-dispersion equation can only be obtained by experiment. Hydraulic mean radius that represents the amount and intensity of flowing water within pores can be obtained by the formula using the factors for physical properties. A slug injection test was conducted and a power type empirical formula for obtaining a longitudinal dispersivity using a hydraulic mean radius in rockfill porous media was derived. It is possible to obtain the longitudinal dispersivity depending on transport distance because it contains a formula for a scale constant, and expected to be applicable to waterways filled with homogeneous gravel and small flow rate.

• Fashion & Textile Research Journal
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• v.24 no.6
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• pp.744-755
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• 2022

This study sought to verify the shopping values that tourists pursue by purchasing at travel destinations based on tourists' motivation and identify the effects of these values on the types of fashion items preferred by tourists. Furthermore, this study verified the tourist shopping behavior of three Asian countries-Korea, China, and Japan-from a cross-cultural perspective. To obtain a sample that represents tourist shoppers in each country, a survey was conducted on adult men and women in their 20s to 60s, and 986 subjects were collected: 300 Koreans, 385 Chinese, and 301 Japanese. Factor analysis, structural equation modeling, and multigroup SEM were performed on the collected data using SPSS Statistics and AMOS. Based on escaping-seeking theory, tourist intentions were divided into escaping and seeking motivations, and tourist shopping values were divided into functional, emotional, and social. The shopping items were divided into materials and experiential goods to understand the difference between the types preferred by tourists according to the perceived value. In addition, differences in tourist shopping behaviors according to the three nationalities were identified. The findings illustrate that the escaping motive affects emotional and social values, whereas the seeking motive affects all three. Moreover, it was confirmed that functional and emotional values affect preference for material and experiential goods, but social value only affects preference for material goods. For the cross-cultural study, differences in tourist shopping behavior according to nationality were identified.

• Proceedings of the Korea Water Resources Association Conference
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• 2023.05a
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• pp.244-244
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• 2023

Both the frequency and the magnitude of hydrometeorological extreme events such as severe floods and droughts are increasing. In order to prevent a damage from the climatic disaster, hydrological models are often simulated under various meteorological conditions. While performing the simulations, a synthetic data generated through time series models which maintains the key statistical characteristics of the sample data are widely applied. However, the synthetic data can easily maintains both the average and the variance of the sample data, but the quantile is not maintained well. In this study, we proposes a data generation method which maintains the quantile of the sample data well. The equations of the former maintenance of variance extension (MOVE) are expanded to maintain quantile rather than the average or the variance of the sample data. The equations are derived and the coefficients are determined based on the characteristics of the sample data that we aim to preserve. Monte Carlo simulation is utilized to assess the performance of the proposed data generation method. A time series data (data length of 500) is regarded as the sample data and selected randomly from the sample data to create the data set (data length of 30) for simulation. Data length of the selected data set is expanded from 30 to 500 by using the proposed method. Then, the average, the variance, and the quantile difference between the sample data, and the expanded data are evaluated with relative root mean square error for each simulation. As a result of the simulation, each equation which is designed to maintain the characteristic of data performs well. Moreover, expanded data can preserve the quantile of sample data more precisely than that those expanded through the conventional time series model.

• Journal of the Korean Society of Safety
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• v.38 no.3
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• pp.35-42
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• 2023

This study analyzed the current and temperature characteristics of major components of an induction motor during normal and abnormal operations as functions of the difference in the rated capacities of medium and large-sized motors widely used in industrial settings. The temperature rise equation of the induction motor winding was derived through locked-rotor operation experiments and linear regression analysis. When the ambient temperature is 40 ℃, the time to reach 155 ℃, the temperature limit of the insulation class (F class) of the winding of the induction motor, was confirmed to be 48 seconds for the 2.2 kW induction motor and 39 seconds for the 3.7 kW induction motor. This means that when the rated capacity is large or the installation environment is high temperature, the time to reach the temperature limit of the insulation class during locked-rotor operation is short, and the risk of insulation deterioration and fire is high. In addition, even if the EOCR (Electronic Over Current Relay) is installed, if the setting time is excessively set, the EOCR does not operate even if the normal and locked-rotor operation of the induction motor is repeated, and the temperature limit of the insulation grade of the winding of the induction motor is exceeded. The results of this study can be used for preventive measures such as the promotion of electrical and mechanical measures for the failure of induction motors and fire prevention in industrial sites, or the installation of fire alarm systems.

• Journal of radiological science and technology
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• v.46 no.4
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• pp.325-336
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• 2023

The purpose of this study was to analyze the structural relationship between job satisfaction levels felt during ultrasound examination of radiological technologists (RTs) using a structural equation model. The subjects were a total of 203 RTs currently working in medical institutions. The method was conducted as a survey study using a questionnaire consisting of a total of 29 questions consisting of demographic characteristics and job satisfaction levels that were self-efficacy, job competency, extrinsic compensation, and job satisfaction. The reliability was secured with the Cronbach's alpha coefficient of 0.6 or higher. For statistical analysis, a significant difference between the frequency analysis of demographic characteristics and the mean of the job satisfaction levels were performed by independent sample T-test and one-way analysis of variance (ANOVA) followed by Scheffe's post hoc test. The correlation analysis between variables was tested with Spearman's and Pearson's correlation coefficient. We analyzed the structural relationships between variables by structural equations. As a result, first, job competency and extrinsic compensation had a positive effect on job satisfaction on ultrasound examination of RTs. Second, the self-efficacy of ultrasound examination RTs showed a high correlation with job competency. Third, the job satisfaction levels showed in the order of job competency, job satisfaction, self-efficacy, and extrinsic compensation. In conclusion, this study are expected to be provided as data to identify factors that could improve job satisfaction during ultrasound examination of RTs by empirically analyzing the structural relationship of self-efficacy, job competency, and external compensation.

• Tribology and Lubricants
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• v.39 no.4
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• pp.139-147
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• 2023

Cavitation phenomena observed during the operation of a submerged plain journal bearing (PJB) can affect bearing performance parameters such as dynamic coefficients, whirl frequency ratio, and critical mass. This study presents numerical solutions of the Reynolds equation for steadily and dynamically loaded submerged PJBs with half-Sommerfeld (HS), Reynolds, and Jakobsson-Floberg-Olsson (JFO) cavitation models when the supply pressure is larger or equal to the cavitation pressure. The loads at various eccentricity ratios are identical; however, the attitude angle is approximately 6% smaller when the eccentricity ratio is between 0.2 and 0.7 and the JFO model is used, compared to that when the Reynolds model is used. Dynamic coefficients obtained with the HS and Reynolds model show good agreement with each other, except for k_xz, which is sensitive to changes in the force normal to the rotor weight, and is attributed to the difference in the attitude angle obtained with each cavitation model. Stiffness coefficients are determined using the pressure distribution in the film, and therefore, when the JFO model is used, the direct stiffness coefficients are affected and show opposite signs for most eccentricity ratios. The mass-conservative JFO model can predict at least a 30% smaller critical mass compared to that using the HS and Reynolds models. Thus, the instability analysis results can change based on the cavitation model used in a submerged PJB. The results of this research indicate that the JFO model should be used when designing a rotor system supported by submerged PJBs.

• Progress in Superconductivity and Cryogenics
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• v.9 no.1
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• pp.22-26
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• 2007

Superconductor is weak in AC condition. Bifilar geometry provides a solution to reduce AC loss. Bifialr geometry is piled up or wound with more than two layers. When a layer of superconductor abuts on other layers, AC loss is affected by not only self-field, but also magnetic field induced by adjacent layers. In this study, two superconductors are piled up as a series connection so that current flows in different directions. By this method, magnetic field is cancelled. If magnetic field is cancelled, AC loss is reduced. To compare AC loss with respect to piling method, we measured the AC loss difference between the case facing each other with substrate side and the case facing with YBCO side. Measured AC loss is compared with one-way current flow single layer AC loss. In addition, we analyzed how much AC loss was increased, or reduced. All results were compared with those calculated with Norris equation. By this experiment, we concluded that distance between two wires is the important cause of AC loss. The distance between two wires affects magnetic field reduction in YBCO and induced current flow on substrate side.

• Journal of Environmental Science International
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• v.31 no.12
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• pp.1013-1025
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• 2022

This study was carried out to analyze water cycle characteristics and evaluate water retention function in Jeju Gotjawal forest from 2013 to 2017. The average ratio of throughfall, stemflow, interception loss in Seonhul Gotjawal (SH) and Cheongsu Gotjawal (CS) was 43.1%, 15.8%, and 41.1%, respectively. Rainfall-throughfall, rainfall-stemflow, and rainfall-interception loss were expressed as linear regression equation (p<0.001). The comparison results showed that SH was higher than CS (p<0.05), indicating that the canopy area had an important effect on the difference in stand structure. The average water resources retention rate of the Gotjawal region was 41.9%, which is similar to the total water resources retention rate (40.6%) of Jeju Special Self-Governing Province (JSSGP). Currently, the development of Gotjawal is in progress in JSSGP. The development of Gotjawal will lead to a decrease in the water resources retention rate due to changes in the surface environment such as an increase in impervious areas, which will affect the total groundwater content of JSSGP. Therefore, the conservation of the Gotjawal area is judged to be very important from the point of view of water conservation.