• Asia-pacific Journal of Multimedia Services Convergent with Art, Humanities, and Sociology
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• v.6 no.9
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• pp.59-70
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• 2016

The rapid development of the Chinese version of Twitter, the groom Weibo has become an important communication means for Chinese SNS users to obtain and share information. As a result, in China, the phenomenon of the power shift has emerged from the traditional opinion leaders to SNS opinion leasers. The relationship analysis of demographic variables of the Chinese SNS users and their Information on the relationship between keywords was made by utilizing the centrality analysis using Social Network Program NetMiner. China's SNS opinion leaders have general interest in daily activities with their families or friends rather than in social issues. And in case of SNS opinion leaders of high betweenness centrality, it was analyzed that general users was a key mediator role that organically out lead to the adjacent information. These properties are not independent of demographic variables, such as professional, therefore, the demographic characteristics of SNS opinion leaders showed a significant effect on the parameters of betweenness centrality. This study analyzed the characteristics of SNS users, especially opinion leaders in China by looking at the aspects of Chinese social phenomenon in terms of information. Through this study, we expect to provide basic information about the social characteristics of China through collective communication.

• Nuclear Engineering and Technology
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• v.55 no.6
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• pp.2139-2146
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• 2023

During reactor operation, the divertor must withstand unprecedented simultaneous high heat fluxes and high-energy neutron irradiation. The extremely severe service environment of the divertor imposes a huge challenge to the bonding quality of divertor joints, i.e., the joints must withstand thermal, mechanical and neutron loads, as well as cyclic mode of operation. In this paper, potassium-doped tungsten (KW) is selected as the plasma facing material (PFM), oxygen-free copper (OFC) as the interlayer, oxide dispersion strengthened copper (ODS-Cu) alloy as the heat sink material, and reduced activation ferritic/martensitic (RAFM) steel as the structural material. In this study, a vacuum brazing technology is proposed and optimized to bond Cu and ODS-Cu alloy with the silver-free brazing material CuSnTi. The most appropriate brazing parameters are a brazing temperature of 940 ℃ and a holding time of 15 min. High-quality bonding interfaces have been successfully obtained by vacuum brazing technology, and the average shear strength of the as-obtained KW/Cu and ODS-Cu alloy joints is ~268 MPa. And a fabrication route for manufacturing the flat-type divertor target based on brazing technology is set. For evaluating the reliability of the fabrication technologies under the reactor relevant condition, the high heat flux test at 20 MW/m² for the as-manufactured flat-type KW/Cu/ODS-Cu/RAFM mockup is carried out by using the Electron-beam Material testing Scenario (EMS-60) with water cooling. This paper reports the improved vacuum brazing technology to connect Cu to ODS-Cu alloy and summarizes the production route, high heat flux (HHF) test, the pre and post non-destructive examination, and the surface results of the flat-type KW/Cu/ODS-Cu/RAFM mockup after the HHF test. The test results demonstrate that the mockup manufactured according to the fabrication route still have structural and interfacial integrity under cyclic high heat loads.

• Nuclear Engineering and Technology
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• v.55 no.5
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• pp.1593-1603
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• 2023

In deterministic and Monte Carlo transport codes, b-delayed emission is included using a group structure where all of the precursors are grouped together in 6 groups or families, but given the increase in computational power, nowadays there is no reason to keep this structure. Furthermore, there have been recent efforts to compile and evaluate all the available b-delayed neutron emission data and to measure new and improved data on individual precursors. In order to be able to perform a transient Monte Carlo simulation, data from individual precursors needs to be implemented in a transport code. This work is the first step towards the development of a tool to explore the effect of individual precursors in a fissile system. In concrete, individual precursor data is included by expanding the capabilities of the open source Monte Carlo code OpenMC. In the modified code - named Time Dependent OpenMC or OpenMC(TD)- time dependency related to β-delayed neutron emission was handled by using forced decay of precursors and combing of the particle population. The data for continuous energy neutron cross-sections was taken from JEFF-3.1.1 library. Regarding the data needed to include the individual precursors, cumulative yields were taken from JEFF-3.1.1 and delayed neutron emission probabilities and delayed neutron spectra were taken from ENDF-B/VIII.0. OpenMC(TD) was tested in a monoenergetic system, an energy dependent unmoderated system where the precursors were taken individually or in a group structure, and in a light-water moderated energy dependent system, using 6-groups, 50 and 40 individual precursors. Neutron flux as a function of time was obtained for each of the systems studied. These results show the potential of OpenMC(TD) as a tool to study the impact of individual precursor data on fissile systems, thus motivating further research to simulate more complex fissile systems.

• Nuclear Engineering and Technology
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• v.55 no.5
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• pp.1802-1813
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• 2023

Conjugate heat transfer between liquid metal and solid is a common phenomenon in a liquid-metal-cooled fast reactor's fuel assembly and heat exchanger, dramatically affecting the reactor's safety and economy. Therefore, comprehensively studying the sophisticated conjugate heat transfer in a liquid-metal-cooled fast reactor is profound. However, it has been evidenced that the traditional Simple Gradient Diffusion Hypothesis (SGDH), assuming a constant turbulent Prandtl number (Pr_t,, usually 0.85 - 1.0), is inappropriate in the Computational Fluid Dynamics (CFD) simulations of liquid metal. In recent decades, numerous studies have been performed on the four-equation model, which is expected to improve the precision of liquid metal's CFD simulations but has not been introduced into the conjugate heat transfer calculation between liquid metal and solid. Consequently, a four-equation model, consisting of the Abe k - ε turbulence model and the Manservisi k_𝜃 - ε_𝜃 heat transfer model, is applied to study the conjugate heat transfer concerning liquid metal in the present work. To verify the numerical validity of the four-equation model used in the conjugate heat transfer simulations, we reproduce Johnson's experiments of the liquid lead-bismuth-cooled turbulent pipe flow using the four-equation model and the traditional SGDH model. The simulation results obtained with different models are compared with the available experimental data, revealing that the relative errors of the local Nusselt number and mean heat transfer coefficient obtained with the four-equation model are considerably reduced compared with the SGDH model. Then, the thermal-hydraulic characteristics of liquid metal turbulent pipe flow obtained with the four-equation model are analyzed. Moreover, the impact of the turbulence model used in the four-equation model on overall simulation performance is investigated. At last, the effectiveness of the four-equation model in the CFD simulations of liquid sodium conjugate heat transfer is assessed. This paper mainly proves that it is feasible to use the four-equation model in the study of liquid metal conjugate heat transfer and provides a reference for the research of conjugate heat transfer in a liquid-metal-cooled fast reactor.

• The Korean Journal of Franchise Management
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• v.3 no.2
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• pp.20-38
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• 2012

After being introduced into franchises industry, franchise has made a phenomenal growth in a short time and a substantial contribution to job creation and economic revitalization. Nevertheless, franchise business operators failed a business or low profit because of a lack of information and indiscriminate foundation. Therefore the first object of this study is characteristics of franchise's factors on disclosure agreement in franchise associate website. second is examinations about casual relationship between factor and franchise performance with using Excel and SPSS 18.0 versions. The findings of present study were as follows. First, franchises manage small business mostly(financial data, scale so on) and franchise's type focused the food service industry. Specially, a business district select unprotected contract. Second, in franchise's factors, we could find statistically significant effect on annual average sales and annual average net profit. However growth rate of franchise don't have statistically significant effect. Third, we could find statistically significant difference on analysis both franchises' factors and financial data. In conclusion, we must consider of franchise industry environment and success effect on performance in starting one's business. Furthermore franchises plan ways for their sustained growth and protection of rights and interests. Finally business operator draw up their information and upgrade continuously for franchises industry growth. Discussion and theoretical and managerial implications of the results were described along with future franchise research suggestions.

• The Korean Journal of Franchise Management
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• v.5 no.1
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• pp.85-108
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• 2014

This study provides the information about size, financial structure, profitability and growth of franchisors using financial data(asset, liability, equity, sales volume, operating income and net income) in uniform franchise offering circular of fair trade commission. The data were collected from 1,050 franchisors in various business fields: fast food, family restaurant, bakery, agriculture & fishery and liquor shop in the uniform franchise offering circular in 2012 and 2011. Results of this study are as follows: For company size, median of total assets was KRW 675 million and the accumulated median assets rate was 0.48%, but the accumulated median company numbers were 49.9%, which showed small size. For financial structure, 525 companies were below 200% debt ratio, while 314 (29.9%) companies were in over 200% debt, and 211 (20.1%) companies were impaired in capital. These also showed financial structure was vulunerable. For profitability, median of ROA for total companies were only 4.72%, which showed low profitability. For growth, median of growth rate for sales were 7.57% per year, which showed mature industry. In overall, the results showed franchisors should improve their financial status.

• Tuberculosis and Respiratory Diseases
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• v.86 no.3
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• pp.203-215
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• 2023

Background: Surgical resection is the standard treatment for early-stage lung cancer. Since postoperative lung function is related to mortality, predicted postoperative lung function is used to determine the treatment modality. The aim of this study was to evaluate the predictive performance of linear regression and machine learning models. Methods: We extracted data from the Clinical Data Warehouse and developed three sets: set I, the linear regression model; set II, machine learning models omitting the missing data: and set III, machine learning models imputing the missing data. Six machine learning models, the least absolute shrinkage and selection operator (LASSO), Ridge regression, ElasticNet, Random Forest, eXtreme gradient boosting (XGBoost), and the light gradient boosting machine (LightGBM) were implemented. The forced expiratory volume in 1 second measured 6 months after surgery was defined as the outcome. Five-fold cross-validation was performed for hyperparameter tuning of the machine learning models. The dataset was split into training and test datasets at a 70:30 ratio. Implementation was done after dataset splitting in set III. Predictive performance was evaluated by R² and mean squared error (MSE) in the three sets. Results: A total of 1,487 patients were included in sets I and III and 896 patients were included in set II. In set I, the R² value was 0.27 and in set II, LightGBM was the best model with the highest R² value of 0.5 and the lowest MSE of 154.95. In set III, LightGBM was the best model with the highest R² value of 0.56 and the lowest MSE of 174.07. Conclusion: The LightGBM model showed the best performance in predicting postoperative lung function.

• Journal of Service Research and Studies
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• v.11 no.1
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• pp.31-44
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• 2021

The net function of the domestic medical insurance system is highly regarded, but due to the problem of incomplete coverage, the public wants to secure coverage through private medical insurance subscription. As a result, the subscription rate of private medical insurance has recently increased, and the billing rate has also increased. As the number of people seeking private medical insurance increased, workers at private medical insurance companies are experiencing increased job stress and side effects, especially for insurance reviewers who are in charge of paying insurance, such as communicating with customers who claimed insurance and contributing to the company's profit. In response, this study analyzed the effects of job stress on mental health of insurance reviewers and conducted a descriptive survey study to reduce job stress of insurance reviewers and promote mental health. The analysis shows that job stress for insurance reviewers has a significant impact on mental health (+). In detail, job stress has a significant impact on all four factors: social performance and self-confidence, depression, sleeping disturbance and anxiety, and general well-being and vitality. This study showed that job stress in insurance reviewers has a significant (+) impact on mental health. Job stress can cause side effects in organizational aspects, such as reducing enthusiasm for job performance and increasing turnover and resignation rates, but it can also worsen individual physical health and cause diseases such as depression and anxiety, causing mental health to be impoverished. Therefore, in order to prevent this, appropriate work stress prevention methods and countermeasures should be provided to help reduce work stress and improve mental health.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.46 no.1
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• pp.84-90
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• 2023

ASL estimation of public building is based on how appropriate the maximum age of the asset is derived based on the age record of the asset in the statistical data owned by public institutions. This is because we get a 'constrained' ASL by that number. And it is especially true because other studies have assumed that the building is an Iowa curve R3. Also, in this study, the survival rate is 1% as the threshold value at which the survival curve and the predictable life curve almost coincide. Rather than a theoretical basis, in the national statistical survey, the value of residual assets was recognized from the net value of 10% of the acquisition value when the average service life has elapsed, and 1% when doubling the average service life has elapsed. It is based on the setting mentioned above. The biggest constraint in fitting statistical data to the Iowa curve is that the maximum ASL is selected at R3 150%, and the 'constrained' ASL is calculated by the proportional expression on the assumption that the Iowa curve is followed. In like manner constraints were considered. First, the R3 disposal curve for the RCC(reinforced cement concrete) building was prepared according to the discarding method in the 2000 work, and it was jointly worked on with the National Statistical Office to secure the maximum amount of vintage data, but the lacking of sample size must be acknowledged. Even after that, the National Statistical Office and the Bank of Korea have been working on estimating the Iowa curve for each asset class in the I-O table. Another limitation is that the asset classification uses the broad classification of buildings as a subcategory. Second, if there were such assets with a lifespan of 115 years that were acquired in 1905 and disposed of in 2020, these discarded data would be omitted from this ASL calculation. Third, it is difficult to estimate the correct Iowa curve based on the stub-curve even if there is disposal data because Korea has a relatively shorter construction history, accumulated economic wealth since the 1980's. In other words, "constrained" ASL is an under-estimation of its ASL. Considering the fact that Korea was an economically developing country in the past and during rapid economic development, environmental factors such as asset accumulation and economic ability should be considered. Korea has a short period of accumulation of economic wealth, and the history of 'proper' architectures faithful to building regulations and principles is short and as a result, buildings 'not built properly' and 'proper' architectures are mixed. In this study, ASL of RCC public building was estimated at 70 years.

• The Journal of the Convergence on Culture Technology
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• v.9 no.2
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• pp.119-126
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• 2023

Due to the COVID-19 phenomenon, more than one-third of SMEs in Korea have been working from home. Therefore, we tried to find out the management status of SMEs and find policy support. The survey data was based on the Bank of Korea's corporate management analysis 2021 data. As a result of the study, the debt of SMEs increased from 362 trillion won(2019) to 409 trillion won(2022), while their capital decreased from 489 trillion won(2019) to 336 trillion won(2022). Net profit and loss increased to 14.9 trillion won(2019) and 23.3 trillion won(2021). As a result of the company's financial soundness analysis, First, for stability, the current ratio was high compared to the total industry and the dependence on borrowings was high. Second, profitability improved from 3.20%(2019) to 4.28%(2021), but it was lower than 5.01%(2021) for all industries. Third, the growth rate showed an increase of 12.43%, which is 1.57 times faster than the total asset growth rate of 7.94%(2021) for all industries. As for the growth rate of sales, all industries(2021) showed (-)growth, while SMEs among manufacturing industries showed a growth rate of 14.78%. Fourth, as for activity, the total asset turnover ratio was higher at 0.96% compared to 0.73 for all industries. In conclusion, stability and profitability were low and growth potential was high compared to all industries. In the future, policies that focus on industries with high growth potential are needed.