• Clean Technology
• /
• v.28 no.1
• /
• pp.46-53
• /
• 2022

The agglomeration characteristics of coal and silica sand were investigated under various conditions using mixed samples consisting of coal, silica sand, and potassium hydroxide, which is an agglomeration accelerator. The samples were prepared by either physically mixing or using aqueous solutions. The experiments using the physically mixed powder samples were performed with a two hour reaction time. The results showed that the number of aggregates generated increased as the reaction temperature and the total potassium content increased. The experiments using aqueous solutions were performed at 880 ℃, which is the operating temperature of a fluidized bed boiler, and at 980 ℃, which assumes a local hot spot. The amount of agglomeration generated as the reaction time increased and the total potassium content increased was identified. In the experiment performed at 880 ℃, the amount of aggregate generated clearly increased with the reaction time, and in the experiment performed at 980 ℃, assuming a local hot spot, a large amount of aggregate was generated in a relatively short time. The aggregates became harder as the potassium content increased. When the total potassium content was less than 1.37 wt.%, the aggregates were weak at both temperatures and collapsed even with a slight impact. Additionally, the surface characteristics of the silica sand and ash aggregates were observed by SEM-EDS analysis. The analysis revealed a large amount of potassium at the bonding sites. This result indicates that there is a high possibility of aggregation in the form of a eutectic compound when the alkali component is increased.

• Korean Journal of Cognitive Science
• /
• v.33 no.1
• /
• pp.51-75
• /
• 2022

Transcranial direct current stimulation (tDCS) is a non-invasive brain stimulation that is able to alter neuronal activity in particular brain regions. Many studies have researched how tDCS modulates neuronal activity and reorganizes neural networks. However it is difficult to conclude the effect of brain stimulation because the studies are heterogeneous with respect to the stimulation parameter as well as individual difference. It is not fully in agreement with the effects of brain stimulation. In particular few studies have researched the reason of variability of brain stimulation in response to time so far. The study investigated individual variability of brain stimulation based on circadian rhythm and chronotype. Participants were divided into two groups which are morning type and evening type. The experiment was conducted by Zoom meeting which is video meeting programs. Participants were sent experiment tool which are Muse(EEG device), tdcs device, cell phone and cell phone holder after manuals for experimental equipment were explained. Participants were required to make a phone in frount of a camera so that experimenter can monitor online EEG data. Two participants who was difficult to use experimental devices experimented in a laboratory setting where experimenter set up devices. For all participants the accuracy of 98% was achieved by SVM using leave one out cross validation in classification in the the effects of morning stimulation and the evening stimulation. For morning type, the accuracy of 92% and 96% was achieved in classification in the morning stimulation and the evening stimulation. For evening type, it was 94% accuracy in classification for the effect of brain stimulation in the morning and the evening. Feature importance was different both in classification in the morning stimulation and the evening stimulation for morning type and evening type. Results indicated that the effect of brain stimulation can be explained with brain state and trait. Our study results noted that the tDCS protocol for target state is manipulated by individual differences as well as target state.

• Korea Journal of Hospital Management
• /
• v.27 no.2
• /
• pp.53-66
• /
• 2022

Aim : The purpose of this study is to investigate the influence of the awareness level of the mandatory employment system for the disabled and the help of the employment increase on the health status of the disabled. Based on this, the purpose of this study is to raise awareness of the compulsory employment system for the disabled and to suggest a way to improve the health of the disabled. Methods : In this study, the first data of the second wave of the 2016-2018 Employment Panel Survey for the Disabled was used to analyze the participation of the disabled in economic activities. a total of 1,648 subjects were analyzed using the chi-square test and generalized estimating equation (GEE). Results : Compared to the group knowing about the compulsory employment system for the disabled, in the group who did not know about the compulsory employment system, the cognitive level was significantly higher for subjective health status (Odds Ratio [OR]: 1.573, 95% Confidence Interval [CI]: 1.252-1.977) and chronic diseases (OR: 1.407, 95% CI: 1.091-1.816), Compared to the group that the compulsory employment system for the disabled is helpful in increasing employment, the group that said it was not helpful at all had depression feel (OR: 2.330, 95% CI: 1.219-4.452) and subjective health status (OR: 2.052, 95% CI: 1.232. -3.416) significantly affected. Conclusion : It was found that the lower the level of awareness and help of the compulsory employment system for the disabled, the negative impact on their health status. Therefore, it is necessary to promote employment growth by raising awareness of the employment system for the disabled. Furthermore, in order to improve the health of the disabled, public relations plans to increase the understanding of the disabled on the system and policies to protect the disabled people who lose their will to work due to difficulties in accessing employment were enacted, and Changes to a disability-friendly working environment should be activated so that participants can participate.

• Journal of Korea Entertainment Industry Association
• /
• v.14 no.3
• /
• pp.201-210
• /
• 2020

The aim of this thesis is to investigate exhibition spaces which are being expanded and transformed concurrently with social phenomena that are also the result of rapid changes, all of which are reflective of a modern society in transition. Such investigation would also include an analysis of changes in the viewing public and artworks themselves, and also an assessment of the public nature of art and its effective aspects. Expansion of exhibition spaces and the increasing connection between art and the public have very important ramifications, in many respects. They present opportunities for the viewing public to immerse themselves in artistic spaces, with some reaching further into other activities - activities that they often share with other individuals. This also leads them to expand their range of activities, turning them into more mobile, proactive audiences. In connection, many corporations have turned their attention to this public aspect of art, which has resulted in a display of art in different types of spaces. The government also began to adopt 'public art' as a matter of policy, using it as a medium of communication between the state and its populace. The public aspect of art, being highlighted as a result of expansion and diversification of exhibition spaces, will have a significant impact not only on the viewing public, but also on the art market. This represents a momentous change for creators of art, which naturally warrants close scrutiny and research.

• 한국노년학
• /
• v.41 no.2
• /
• pp.217-240
• /
• 2021

The purpose of this study is to examine the effect of care workers' employment characteristics and perception of facility directors' transformational leadership on quality of service through a hierarchical linear model. For this aim, survey data were collected amongst 240 older adults and 200 care workers who are affiliated within 45 long-term care facilities in Seoul, and analyzed using SPSS 26.0 and HLM 8.0. As a result, one's perception of transformational leadership had a positive effect, whereas, among employment characteristics, employment type and working hours had negative effects on quality of service. Regular workers with fewer working hours and higher awareness of transformational leadership toward the director provided higher quality of service. But wage, total experience and tenure didn't meaningfully affect it. Therefore, the following suggestions were presented. First, it is necessary to reorganize incentive, salary systems and budgets, changing the status of temporary workers' hourly wage system into that of regular workers' monthly one in order to strengthen employment security with acknowledging fundamental professional values through reinforcement of expertise. Reinforcement of long-term care's publicness and establishment of base facilities are also suggested. Second, maintaining appropriate hours of work and rest including annual leave under the Labor Standards Act is needed. Also, increasing the salary of and decreasing working hours for night shift workers are required. Third, education and intervention for inspiring transformational leadership of directors and strengthening qualification standards of them are required.

• 한국노년학
• /
• v.41 no.4
• /
• pp.547-566
• /
• 2021

The purpose of this study is to analyze the effect of social activities on healthy life expectancy (HLE) by gender difference. HLE implies an estimate of how long an individual can expect to live in full health or without disease and/or disability. Morbidity, mortality, and functional health status usually have been known as key variables. Many researchers have tried to investigate factors affecting HLE in countries level by performing comparative analyses. In micro level, there have been some studies about social factors affecting HLE in individual level. However, few studies are found focusing on the relationship between HLE and social activities. This study anlayzes 4,029 over 65 years of age from the first wave (2006) to the seventh wave (2018) of the Korean Longitudinal Study of Ageing (KLoSA), which is a national panel data collected by Korea Employment Information Service. The data has been collected as a part of social and economic policies planning for Korean government. HLE was measured by life period without disease or disability. One of findings is that male older adults (76.9 yrs) show higher HLE in comparing to female group (75.3 yrs). Female group appeared to be more likely to have higher incidence rate and disorders. Another finding indicates that age, number of chronic diseases, and subjective health status affect HLE of both groups. Finally, regarding social activities, religion affiliated activities appear to significantly affect HLE of both groups. In case of male older adults, alumni or hometown gathering also appeared another activities affecting HLE. This study indicates that the effect of social activities types on HLE among older adults appears differently by gender. Further, unlikely of longer life expectancy among female older adults as known, HLE shows a reverse estimate, longer healthy life expectancy among male older adults. This finding may imply that later life of female older adults shows lower quality of life in comparing to that of male group, even if female life expectancy has been higher. This study encourages to develop more social activity programs for older adults in community level. Specifically, more attention is required to planning for programs targeting female older adults.

• Journal of the Korean Institute of Landscape Architecture
• /
• v.50 no.3
• /
• pp.19-34
• /
• 2022

This study was conducted to provide basic data that can be used when establishing Net Zero policies and implementation plans for non-urban settlements by quantitatively analyzing the Net Zero contribution to green infrastructure in rural areas corresponding to non-urban settlements. The main purpose is to first, systematize green infrastructure in rural areas, secondly derive basic units for each element of green infrastructure, and thirdly quantify and present the impact on Net Zero in Korea using these. In this study, CVR(Content Validity Ration) analysis was performed to verify the adequacy of green infrastructure elements in rural areas derived through research and analysis of previous studies, is as follows. First, Hubs of Green infrastructure in rural area include village forests, wetlands, farm land, and smart farms with a CVR value of .500 or higher. And Links of Green infrastructure in rural area include streams, village green areas, and LID (rainwater recycling). Second, the basic unit for each green infrastructure element was presented by classifying it into minimum, maximum, and median values using the results of previous studies so that it could be used for spatial planning and design for Net Zero. Third, when Green infrastructure in rural areas is applied to non-urban settlements in Korea, it is analyzed that it has the effect of indirectly reducing CO₂ by at least 70.76 million tons and up to 141.16 million tons. This is 3.4 to 6.7 times the amount of CO₂ emission from the agricultural sector in 2019, and it can be seen that the contribution to Net Zero is very high. It is expected to greatly contribute to the transformation of the ecosystem. This study quantitatively presented the carbon-neutral contribution to settlements located in non-urban areas, and by deriving the carbon reduction unit for each element of green infrastructure in rural areas, it can be used in spatial planning and design for carbon-neutral at the village level. It has significance as a basic research. In particular, the basic unit of carbon reduction for each green infrastructure factors will be usable for Net Zero policy at the village level, presenting a quantitative target when establishing a plan, and checking whether or not it has been achieved. In addition, based on this, it will be possible to expand and apply Net Zero at regional and city units such as cities, counties, and districts.

• Journal of Korea Port Economic Association
• /
• v.37 no.4
• /
• pp.127-144
• /
• 2021

The purpose of this study is to derive service factors based on the "Rail Statistical Yearbook" data of railroad service providers from 1990 to 2019, and to analyze the effect of the service factors on the operating profit ratio(OPR), a representative management performance variable of railroad transport service providers. In particular, it has academic significance in terms of empirical research to evaluate whether the management innovation of the KoRail has changed in line with the purpose of establishing the corporation by dividing the research period into the first period (1990-2003) and the latter (2004-2019). The contents of this study investigated previous studies on the quality of railway passenger transportation service and analyzed the contents of government presentation data related to the management performance evaluation of the KoRail. As an empirical analysis model, a research model was constructed using OPR as a dependent variable and service factor variables of infrastructure, economy, safety, connectivity, and business diversity as explanatory variables based on the operation and management activity information during the analysis period 30 years. On the results of research analysis, OPR is that the infrastructure factor is improved by structural reform or efficiency improvement. And economic factors are the fact that operating profit ratio improves by reducing costs. The safety factor did not reveal the significant explanatory power of the regression coefficient, but the sign of influence was the same as the prediction. Connectivity factor reveals a influence on differences between first period and latter, but OPR impact direction is changed from negative in before to positive in late. This is an evironment in which connectivity is actually realized in later period. On diversity factor, there is no effect of investment share in subsidiaries and government subsidies on OPR.

• Journal of Korea Port Economic Association
• /
• v.37 no.4
• /
• pp.161-173
• /
• 2021

The shipping industry plummeted and was depressed due to the global economic crisis caused by the bankruptcy of Lehman Brothers in the US in 2008. In 2020, the shipping market also suffered from a collapse in the unstable global economic situation due to the COVID-19 pandemic, but unexpectedly, it changed to an upward trend from the end of 2020, and in 2021, it exceeded the market of the boom period of 2008. According to the Clarksons report published in May 2021, the decrease in cargo volume due to the COVID-19 pandemic in 2020 has returned to the pre-corona level by the end of 2020, and the tramper bulk carrier capacity of 103~104% of the Panamax has been in the ports due to congestion. Earnings across the bulker segments have risen to ten-year highs in recent months. In this study, as factors affecting BDI, the capacity and congestion ratio of Cape and Panamax ships on the supply side, iron ore and coal seaborne tonnge on the demand side and Granger causality test, IRF(Impulse Response Function) and FEVD(Forecast Error Variance Decomposition) were performed using VAR model to analyze the impact on BDI by congestion caused by strengthen quarantine at the port due to the COVID-19 pandemic and the loading and discharging operation delay due to the infection of the stevedore, etc and to predict the shipping market after the pandemic. As a result of the Granger causality test of variables and BDI using time series data from January 2016 to July 2021, causality was found in the Fleet and Congestion variables, and as a result of the Impulse Response Function, Congestion variable was found to have significant at both upper and lower limit of the confidence interval. As a result of the Forecast Error Variance Decomposition, Congestion variable showed an explanatory power upto 25% for the change in BDI. If the congestion in ports decreases after With Corona, it is expected that there is down-risk in the shipping market. The COVID-19 pandemic occurred not from economic factors but from an ecological factor by the pandemic is different from the past economic crisis. It is necessary to analyze from a different point of view than the past economic crisis. This study has meaningful to analyze the causality and explanatory power of Congestion factor by pandemic.

• Korean Journal of Remote Sensing
• /
• v.38 no.5_1
• /
• pp.627-646
• /
• 2022

Recently, the seriousness of climate change-related problems caused by global warming is growing, and the average temperature is also rising. As a result, it is affecting the environment in which various temperature-sensitive creatures and creatures live, and changes in the ecosystem are also being detected. Seasons are one of the important factors influencing the types, distribution, and growth characteristics of creatures living in the area. Among the most popular and easily recognized plant seasonal phenomena among the indicators of the climate change impact evaluation, the blooming day of flower and the peak day of autumn leaves were modeled. The types of plants used in the modeling were forsythia and cherry trees, which can be seen as representative plants of spring, and maple and ginkgo, which can be seen as representative plants of autumn. Weather data used to perform modeling were temperature, precipitation, and solar radiation observed through the ASOS Observatory of the Korea Meteorological Administration. As satellite data, MODIS NDVI was used for modeling, and it has a correlation coefficient of about -0.2 for the flowering date and 0.3 for the autumn leaves peak date. As the model used, the model was established using multiple regression models, which are linear models, and Random Forest, which are nonlinear models. In addition, the predicted values estimated by each model were expressed as isopleth maps using spatial interpolation techniques to express the trend of plant seasonal changes from 2003 to 2020. It is believed that using NDVI with high spatio-temporal resolution in the future will increase the accuracy of plant phenology modeling.