• Journal of Sasang Constitution and Immune Medicine
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• v.24 no.3
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• pp.69-79
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• 2012

Objectives This study was performed to research the biological change after walking program in forest according to Sasang constitution. Methods Twenty four applicants are involved in this study. They were classified into three groups(Soyangin, Taeeumin, Soeumin) by QSCC II and divided into two groups(roadway, forest path) by place. And then they participated in walking program on March 31 in 2012. We performed before and after measurements, including active oxygen, biochemical test(BC), and stress hormones. Results Cortisol decreased in the entire group after walking program, which means the effect of relaxation. Glucose reduced in Soyangin group while increased in Taeeumin and Soeumin group after the program. There was no correlation in the test results between Sasang constitution and walking place. Conclusions Walking program has shown most efficacy in relaxation. However a single positive result within this study should be carefully interpreted. In the future, well-designed studies for Sasang constitutional walking program are needed.

• Current Photovoltaic Research
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• v.2 no.3
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• pp.88-94
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• 2014

The structural, optical and electrical properties of sputter-deposited CIGS films were directly influenced by the sputtering process parameters such as substrate temperature, working pressure, RF power and distance between target and substrate. CIGS thin films deposited by using a quaternary target revealed to be Se deficient due to Se low vapor pressure. This Se deficiency affected the overall stoichiometry of the films, causing the films to be Cu-rich. Current tends to pass through the Cu-Se channels which act as the shunting path increasing the film conductivity. The crystal structure of CIGS thin films depends on the substrate orientation due to the influence of surface morphology, grain size and stress of Mo substrate. The excess of Cu was removed from the CIGS films by KCN treatment, achieving a suitable Cu concentration (referred as Cu-poor) for the fabrication of solar cell. Due to high Cu concentrations on the CIGS film surface induced by Cu-Se phases after CIGS film deposition, KCN treatment proved to be necessary for the fabrication of high efficiency solar cells. Also during KCN treatment, dislocation density and lattice parameter decreased as excess Cu was removed, resulting in increase of bandgap and the decrease of conductivity of CIGS films. It was revealed that Cu-Se secondary phase could be removed by KCN wet etching of CIGS films, allowing the fabrication of high efficiency absorber layer.

• Journal of Korean Association for Spatial Structures
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• v.12 no.2
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• pp.89-98
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• 2012

This study investigates the optimum structural design of space truss considering global buckling, and is to obtain the minimal weight of the structure. The mathematical programming method is used for optimization of each member by member force. Besides, dynamic programming method is adapted for consideration in snap-through buckling. The mathematical modeling for optimum design of truss members consists of objective function of total weight and constrain equations of allowable tensile (or compressive) stress and slenderness. The tangential stiffness matrix is examined to find the critical point on equilibrium path, and a ratio of the buckling load to design load is reflected in iteration procedures of dynamic programming method to adjust the stiffness of space truss. The star dome is examined to verify the proposed optimum design processor. The numerical results of the model are conversed well and satisfied all constrains. This processor is a relatively simple method to carry out optimum design with consideration in global buckling, and is viable in practice with respect to structural design.

• Steel and Composite Structures
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• v.10 no.3
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• pp.207-222
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• 2010

Fire incident in buildings is common, so the fire safety design of the framed structure is imperative, especially for the unprotected or partly protected bare steel frames. However, software for structural fire analysis is not widely available. As a result, the performance-based structural fire design is urged on the basis of using user-friendly and conventional nonlinear computer analysis programs so that engineers do not need to acquire new structural analysis software for structural fire analysis and design. The tool is desired to have the capacity of simulating the different fire scenarios and associated detrimental effects efficiently, which includes second-order P-D and P-d effects and material yielding. Also the nonlinear behaviour of large-scale structure becomes complicated when under fire, and thus its simulation relies on an efficient and effective numerical analysis to cope with intricate nonlinear effects due to fire. To this end, the present fire study utilizes a second-order elastic/plastic analysis software NIDA to predict structural behaviour of bare steel framed structures at elevated temperatures. This fire study considers thermal expansion and material degradation due to heating. Degradation of material strength with increasing temperature is included by a set of temperature-stress-strain curves according to BS5950 Part 8 mainly, which implicitly allows for creep deformation. This finite element stiffness formulation of beam-column elements is derived from the fifth-order PEP element which facilitates the computer modeling by one member per element. The Newton-Raphson method is used in the nonlinear solution procedure in order to trace the nonlinear equilibrium path at specified elevated temperatures. Several numerical and experimental verifications of framed structures are presented and compared against solutions in literature. The proposed method permits engineers to adopt the performance-based structural fire analysis and design using typical second-order nonlinear structural analysis software.

• Journal of Korean Academy of Nursing
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• v.48 no.5
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• pp.565-577
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• 2018

Purpose: The purpose of this study was to construct and test a hypothetical model about impact of parents' problem drinking on suicidal ideation of their children who are university students and the multiple mediating effects of childhood trauma, experiential avoidance, and depression based on stress-vulnerability model. Methods: A purposive sample of 400 university students was recruited from three universities in provincial areas and the data were collected between October and November 2016. The collected data were then analyzed using SPSS 20.0 and AMOS 20.0 programs. For data analysis, descriptive statistics, factor analysis, and structural equation modeling were performed. Multiple mediating effects analysis using phantom variable and bootstrapping were implemented to verify the mediating effect of the research model. Results: We found no significant direct effect on depression and suicidal ideation of parents' problem drinking, but multiple mediating effects of childhood trauma and experiential avoidance between parents' problem drinking and depression (B=.38, p=.001). The path from parents' problem drinking to suicidal ideation was significantly mediated by childhood trauma and depression (B=.02, p=.016) and by childhood trauma, experiential avoidance, and depression (B=.05, p=.011), but experiential avoidance did not have a significant direct effect on suicidal ideation (B=.02, p=.616). Conclusions: Based on the results of this study, it can be suggested that in order to decrease depression and prevent suicide of university students, considering of parents' problem drinking and childhood trauma, intervention methods that decreased chronic use of experiential avoidance and strengthen acceptance should be developed and made available to them.

• Journal of Korean Association for Spatial Structures
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• v.13 no.2
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• pp.83-91
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• 2013

The core aim of this dissertation is to empirically scrutinize a strength characteristic of beam-column frame subjected to the cyclic lateral load, a beam-column frame of un-reinforced masonry wall, and a shear wall frame. First and foremost, I embark upon making three prototypes vis-$\grave{a}$-vis this research. By conducting this process, I touch on an analysis of cyclic behavior and a damage characteristic of the beam-column frame, the beam-column frame of un-reinforced masonry wall, and the shear wall frame. What is more, through the previous procedure, the next part delves into the exact stress transfer path and the destructive mechanism to examine how much and how strong the beam-column frame of un-reinforced Masonry Wall does have a resistance capacity against earthquake in all the architecture constructed by the above-mentioned frame, as well as school buildings. In addition to the three prototypes, two more experimental models, a beam-column frame and shear wall frame, are used to compare with the beam-column frame of un-reinforced masonry wall. Lastly, the dissertation will suggest some solutions to improve the resistance capacity against earthquake regarding all constructions built with non bearing wall following having examining precisely all the analysis with regard to not only behavior properties and the damage mechanism of the beam-column frame and the beam-column frame of un-reinforced Masonry Wall but also the resistance capacity against earthquake of non bearing wall and school buildings.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.1
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• pp.290-296
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• 2019

Head-up displays for vehicles play an important role in displaying various information about the safety and convenience of driving on the windshield of the vehicle. In this study, ultra-precision machining was performed and evaluated as a method for machining a large-area aspheric free-form mirror that is applicable to augmented reality technology. Precision diamond cutting is highly accurate and suitable for the production of advanced parts with excellent surface integrity, low surface roughness, and low residual stress. By using an aspheric free-form mold, it is possible to improve the optical transfer function, reduce the distortion path, and realize a special image field curvature. To make such a mold, the diamond cutting method was used, and the result was evaluated using an aspherical shape-measuring machine. As a result, it was possible to the mold with shape accuracy (PV) below $1{\mu}m$ and surface roughness (Ra) below $0.02{\mu}m$.

• Journal of Technologic Dentistry
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• v.41 no.3
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• pp.233-244
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• 2019

Purpose: The purpose of the study is to learn the importance of self-directed learning about career-preparation behavior of department of dental technology students. Methods: Using the questionnaire, the department of dental technology in Gyeongnam Province conducted a survey of students of department of dental technology at A and B college for one month from May 15, 2019 through June 15, 2019, and finally 204 students were surveyed for Self-esteem, Self-determination, Self-efficacy, Internal control, College life adaptation, Self-directed learning, and Career-preparation behavior. Results: Self-esteem among students has been shown to improve self-directed learning by increasing the stress of college life, and self-efficacy has only a direct effect on self-directed learning. In addition, self-determination and internal control of department of dental technology students were found to be variables that have a common positive effect on college life adaptation and self-directed learning. In addition, college life adaptation gives direct positive effect to self-directed learning, but indirect effect through self-directed learning was found to be stronger than direct effect on career-preparation behavior, and the career-preparation behavior of students was further strengthened through self-directed learning. Conclusion: The changes in college restructuring and various policies also suggest that students should actively seek ways to instill certainty about their major's vision and career path within the college rather than deciding their future through extreme measures such as academic secession at a time when anxiety and uncertainty about their career is strong.

• 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.

• Composites Research
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• v.36 no.2
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• pp.108-116
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• 2023

In this paper, kinematic design and multi-body dynamics analysis were conducted to develop a small manipulator platform for automating the maintenance of structures made of composite materials. To design manipulator kinematically, the existing composite repair process was considered. The 3D design was conducted after selecting the basic specifications of manipulator and end-effecter in consideration of the patch lamination process for repair. Then, variables necessary for simulation and control were generated in MATLAB through inverse kinematic analysis. To evaluate the structural stability of platform, multibody dynamics analysis was conducted using Altair Inspire and Optistruct. Based on the simulation conducted in Inspire, multibody dynamics analysis was conducted in Optistruct, and structural stability was verified through the results of maximum displacement and Von-Mises stress over time. To verify the design, manufacturing and controlling of platform were conducted and compared with the simulation. It was confirmed that the actual repair process path and the simulation showed a good agreement.