• Sleep Medicine and Psychophysiology
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• v.28 no.1
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• pp.34-42
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• 2021

Objectives: This study investigated sleep quality in female full-time homemakers and evaluated the relationship of sleep disturbance with psychological and socio-environmental factors. Methods: This cross-sectional study adopted a structured survey and sequential recruitment method for randomized participation of community-dwelling full-time female homemakers. Sleep quality and mental health were measured using the Korean version of the Pittsburgh Sleep Quality Index (K-PSQI), Korean version of the Beck Depression Inventory-II (K-BDI-II), Korean version of the Beck Anxiety Inventory (K-BAI), and Korean version of the Beck Hopelessness Scale (K-BHS). The willingness-to-pay (WTP) method was selected to measure the self-evaluated monetary value of household service work. The relationship among the main relevant factors was statistically analyzed through a mediation model. Results: A total of 166 participants were analyzed and classified having poor versus good sleep quality (poor : 24.1%, n = 40 ; good : 75.9%, n = 126 ; cut-off point = 9 on the K-PSQI). Significant between-group differences were observed in mental health status (K-BDI-II, p < 0.001 ; K-BAI, p < 0.001 ; K-BHS, p = 0.003). The moderated mediation model was verified, indicating that depression may mediate the association between nurturing burden and sleep disturbance. The path from nurturing burden to depression may be moderated by average monthly household income. Conclusion: A relatively high portion of full-time female homemakers may suffer from sleep disturbance and interactions between psychological and socio-environmental factors might determine sleep quality, suggesting the need for public health policies targeting improvement of sleep quality and mental health among full-time homemakers.

• 한국체육학회지인문사회과학편
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• v.58 no.2
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• pp.363-372
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• 2019

This study examined current system of qualification for dance teacher and curriculums along with their actual state, and sought to suggest methods to improve system of qualification for teacher among secondary school dance teachers by type and curriculums. Firstly, through literature analysis, the study examined systems and methods related with acquiring certificate for the current secondary school teacher (2nd grade) and for culture & art teacher for physical education (2nd grade) at the time when preliminary teachers qualified as secondary school dance teacher turned out. And then, using instrumental case study, it analyzed main issues and discourses by examining the cases in which they acquired qualification for secondary school teacher and qualification for dance teacher. Building on this, the study suggested how to improve systems in regard to qualification for dance teachers among regular teachers of secondary school, acquisition path, method and curriculum.

• Nuclear Engineering and Technology
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• v.54 no.4
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• pp.1421-1430
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• 2022

The computation of the solid angle and the detector efficiency is considering to be one of the most important factors during the measuring process for the radioactivity, especially the cylindrical γ-ray NaI(Tl) detectors nowadays have applications in several fields such as industry, hazardous for health, the gamma-ray radiation detectors grow to be the main essential instruments in radiation protection sector. In the present work, a generic numerical simulation method (NSM) for calculating the efficiency of the γ-ray spectrometry setup is established. The formulas are suitable for any type of source-to-detector shape and can be valuable to determine the full-energy peak and the total efficiencies and P/T ratio of cylindrical γ-ray NaI(Tl) detector setup concerning the truncated conical radioactive source. This methodology is based on estimate the path length of γ-ray radiation inside the detector active medium, inside the source itself, and the self-attenuation correction factors, which typically use to correct the sample attenuation of the original geometry source. The calculations can be completed in general by using extra reasonable and complicate analytical and numerical techniques than the standard models; especially the effective solid angle, and the detector efficiency have to be calculated in case of the truncated conical radioactive source studied condition. Moreover, the (NSM) can be used for the straight calculations of the γ-ray detector efficiency after the computation of improvement that need in the case of γ-γ coincidence summing (CS). The (NSM) confirmation of the development created by the efficiency transfer method has been achieved by comparing the results of the measuring truncated conical radioactive source with certified nuclide activities with the γ-ray NaI(Tl) detector, and a good agreement was obtained after corrections of (CS). The methodology can be unlimited to find the theoretical efficiencies and modifications equivalent to any geometry by essential sufficiently the physical selective considered situation.

• Geomechanics and Engineering
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• v.28 no.6
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• pp.613-624
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• 2022

A study of the evolution of overburden fractures under the solid-fluid coupling state was conducted based on the geological and mining characteristics of the coal seam depth, weak strata cementation, and high-intensity mining in the mining areas of West China. These mining characteristics are key to achieving water conservation during mining or establishing groundwater reservoirs in coal mines. Based on the engineering background of the Daliuta Coal Mine, a non-hydrophilic simulation material suitable for simulating the weakly cemented rock masses in this area was developed, and a physical simulation test was carried out using a water-sand gushing test system. The study explored the spatial distribution and dynamic evolution of the fractured zone in the mining overburden under the coupling of stress and seepage. The experimental results show that the mining overburden can be vertically divided into the overall migration zone, the fracture extension zone and the collapse zone; additionally, in the horizontal direction, the mining overburden can be divided into the primary fracture zone, periodic fracture zone, and stop-fracture zone. The scope of groundwater flow in the overburden gradually expands with the mining of coal seams. When a stable water inrush channel is formed, other areas no longer generate new channels, and the unstable water inrush channels gradually close. Finally, the primary fracture area becomes the main water inrush channel for coal mines. The numerical simulation results indicate that the overlying rock breaking above the middle of the mined-out area allows the formation of the water-conducting channel. The water body will flow into the fracture extension zone with the shortest path, resulting in the occurrence of water bursting accidents in the mining face. The experimental research results provide a theoretical basis for the implementation of water conservation mining or the establishment of groundwater reservoirs in western mining areas, and this theoretical basis has considerable application and promotion value.

• Journal of the Korean Electrochemical Society
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• v.25 no.4
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• pp.125-133
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• 2022

Along with the increasing need for point-of-care diagnostics, development of portable, user-friendly, as well as sensitive sensors have gained intensive attention. Among various strategies, electrochromic sensors, which are electrochemically operated colorimetric sensors, have been actively studied. With their ability to report the presence and concentration of analytes by optical signals, electrochromic sensors utilize the advantages of both electrochemical and colorimetric sensors, enabling the simplification of device composition as well as convenient interpretation of results. Up to date, electrochromic sensors have been applied for a wide range of analytes, and further developments such as the introduction of flexible platforms or self-powered systems have been reported, providing a path towards the development of wearable sensor devices. In this review, various types of electrochromic sensors, according to the main strategy in which the electrochemical signals are converted to colorimetric signals, are introduced.

• Journal of the Korean Society of Propulsion Engineers
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• v.27 no.1
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• pp.37-48
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• 2023

In this study, performance analysis modeling of two spool mixed flow type turbofan engine according to steady-state and transient is performed. The target engine is selected as F100-PW-229 from Pratt & Whitney, and main engine components including fan, high pressure compressors, combustion, high pressure turbines, low pressure turbines, mixer, convergent-divergent nozzle are modeled. The cooling effect of turbine through secondary flow path are considered in engine simulation model. We develop in-house Matlab/Simulink-based engine performance analysis program capable of analyzing internal engine state and compare it with GASTURB which is generally used as a commercial engine analysis program.

• The Journal of the Convergence on Culture Technology
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• v.9 no.1
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• pp.457-462
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• 2023

Director Yoon Jong-bin's new series <The Accidental Narco, Narco-Saints> was streamed through Netflix in 2022 and ranked first in the series rankings. <The Accidental Narco, Narco-Saints> continues the genealogy of male narratives in Korean society that director Yoon Jong-bin has pursued for a long time. In <The Accidental Narco, Narco-Saints>, the main characters choose the path of the diaspora to escape Korean society and seek survival in a foreign country. The two male protagonists of <The Accidental Narco, Narco-Saints> are set up in a hostile relationship, but they have one thing in common: they basically pursue money to "survive". They chose the diaspora to avoid the tyranny of public power in Korean society in the 1980s and 1990s, but Republic of Suriname was the worst place where private violence and public power were completely callused. In there, one becomes a drug lord and the other chooses to act for his duty to Korea. These two different choices can be said to be examples of the light and shade of the diaspora. In <The Accidental Narco, Narco-Saints>, director Yoon Jong-bin inherited the themes of 'family' and 'violence' from previous works, while expanding the geographical area of Korean male narratives he had been exploring.

• Journal of the Korean Society of Industry Convergence
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• v.26 no.2_2
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• pp.327-332
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• 2023

As interest in eco-friendly and fuel-efficient electric vehicles has increased globally, there has also been a growing interest in the efficiency, vibration, and noise of motors for electric vehicles Electric vehicles generally have significantly lower driving ranges per charge compared to the maximum driving range per fueling of internal combustion engine vehicles. Additionally, there are issues with various vibrations and noise generated by the motor that can cause discomfort for passengers. Therefore, research is necessary to reduce losses, vibration, and noise of the motor to improve the driving range of electric vehicles. IPMSM with a purchased design can obtain additional reluctance torque by utilizing the difference in inductance between the d and q axes. However, due to this reluctance torque, torque ripple occurs larger than other motors. The increase in torque ripple also increases noise and vibration. Since the reluctance torque, which is the main cause of torque ripple, is determined by the shape of the motor components, torque ripple can be reduced through shape optimization. In this paper, a rotor shape for reducing torque ripple and core loss that causes vibration, noise, and efficiency to decrease of IPMSM for electric vehicles was proposed. Optimization design was carried out by changing the shape of the q-axis path of the rotor to reduce the difference in inductance of the d and q-axis of the rotor. Finally, in order to verify the validity of the design variables derived through the optimal design, the original model and the improved model were compared through the FEM. Compared to the original model, the improved model's torque verifying ripple was reduced by about 62% and core loss was reduced by about 29%, the superiority of the improved model.

• 한국노년학
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• v.39 no.3
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• pp.451-465
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• 2019

This study focuses on the relationship between living alone and depression of the elderly, and explores the possibility that loneliness mediates the relationship between the living alone and the level of depression in Korean Elderly. The sample of the study consists of 1000 elderly aged 65 and above living in Chuncheon. The data is analyzed with the path analysis method with OLS regression method. The main results of this study are as follows. First, the level of loneliness showed a significant difference according to whether they were living alone. The reason for the difference was that the elderly living alone had less intimate relationship comparing with the elderly living with others and did not feel that they had the sense of belonging or intimate relationship with others. Second, it was confirmed that controlling the loneliness, the living alone showed no direct relationship with depression, but it's indirect effect through loneliness was significant.

• Korean Journal of Social Welfare Studies
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• v.40 no.2
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• pp.253-283
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• 2009

This study examined empirically the effect mechanism of labor market structure on access to social insurance. Data were derived from the second wave of Korea Welfare Panel Study in 2007 with a sub-sample of 3,790 of wage workers. Path analysis and structural equation model were used to analyze the effect mechanism. Findings confirmed the inequality of labor market by revealing high causal relationships among occupations and jobs, size of the firm, employment forms, and income. The results suggest that access to social insurance depends on the structural interaction of labor market rather than on the individual worker's trait. Small enterprises and non-standard employment were indicated as the main element explaining the unequal access to social insurance. Finally this study identified women's experience of intensive inequalities in the labor market status and access to social insurance.