• 한국윤활학회:학술대회논문집
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• 한국윤활학회 1998년도 제27회 춘계학술대회
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• pp.149-158
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• 1998

The thermal deformation of the contact seal components has been analyzed using the finite element method. The temperature distributions, the thermal deformations and contact stresses are solved numerically for the contact surface with wear coning effects. The thermal deformation is always shown to distort the sealing surface along the radius of the seal ring. The results show that the deformations of inner radius side are significant compared with those of outer radius. Thus, the thermal deformation due to thermal heatings may promote the coned face wear or wear related thermal cracks at the contacting face of the seal ring component.

• 대한금속재료학회지
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• 제48권5호
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• pp.456-461
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• 2010

We investigated the In-based ohmic contacts on Nitrogen-face (N-face) n-type GaN, as well as Ga-face n-type GaN, for InGaN-based vertical Light Emitting Diodes (LEDs). For this purpose, we fabricated Circular Transfer Length Method (CTLM) patterns on the N-face n-GaN that were prepared by using a laser-lift off method, as well as on the Ga-face n-GaN that were prepared by using a dry etching method. Then, In/transparent conducting oxide (TCO) and In/TiW schemes were deposited on the CTLM in order for low resistance ohmic contacts to form. The In/TCO scheme on the Ga-face n-GaN showed high specific contact resistance, while the minimum specific contact resistance was only 3${\times}$10$^{-2}$ $\Omega$-cm$^{2}$ after annealing at 300${^{\circ}C}$, which can be attributed to the high sheet resistance of the TCO layer. In contrast, the In/TiW scheme on the Ga-face n-GaN produced low specific contact resistance of 2.1${\times}$10$^{5}$ $\Omega$-cm$^{2}$ after annealing at 500${^{\circ}C}$ for 1 min. In addition, the In/TiW scheme on the N-face n-GaN also resulted in a low specific contact resistance of 2.2${\times}$10$^{-4}$ $\Omega$-cm$^{2}$ after annealing at 300${^{\circ}C}$. These results suggest that both the Ga-face n-GaN and N-face n-GaN.

• 농업과학연구
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• 제47권2호
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• pp.327-335
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• 2020

The purpose of this study was to analyze the load distribution and contact safety factor for the power take off (PTO) gear of a 71 kW class agricultural tractor. In this study, a simulation model of the PTO gear-train was developed using Romax DESGINER. The face load factor and contact safety factor were calculated using ISO 6336:2006. The simulation time was set at 2,736 hours considering the lifetime of the tractor, and the simulation was performed for each PTO gear stage at the engine rated power conditions. As a result of the simulation, the face load factors for the driving gear at the PTO 1^st, 2^nd and 3^rd stages were 1.644, 1.632, and 1.341, respectively. The contact safety factors for the driving gear at the PTO 1^st, 2^nd and 3^rd stages were 1.185, 1.216, and 1.458, respectively. As the PTO gear stage was increased, the face load factor decreased, and the contact safety factor increased. The load distributions for all the PTO gears were concentrated to the right of the tooth width. This causes stress concentrations and shortens the lifespan of the gears. Therefore, it is necessary to improve the face load factor and the contact safety factor with macro-geometry and micro-geometry.

• Steel and Composite Structures
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• 제16권4호
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• pp.389-415
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• 2014

This study deals with dynamic model of composite sandwich panels with functionally graded flexible cores under low velocity impacts of multiple large or small masses using a new improved higher order sandwich panel theory (IHSAPT). In-plane stresses were considered for the functionally graded core and face sheets. The formulation was based on the first order shear deformation theory for the composite face sheets and polynomial description of the displacement fields in the core that was based on the second Frostig's model. Fully dynamic effects of the functionally graded core and face-sheets were considered in this study. Impacts were assumed to occur simultaneously and normally over the top and/or bottom of the face-sheets with arbitrary different masses and initial velocities. The contact forces between the panel and impactors were treated as internal forces of the system. Nonlinear contact stiffness was linearized with a newly presented improved analytical method in this paper. The results were validated by comparing the analytical, numerical and experimental results published in the latest literature.

• 가정과삶의질연구
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• 제22권3호
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• pp.23-34
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• 2004

This study was conducted to identify the characteristics of paternal and maternal grandmothers' social support, and to investigate the relationship between paternal and maternal grandmothers' social support and their school-aged grandchildren's psychological adaptation. The participants of this study were 215 students in the 5th and 6th grades and their mothers residing in Daegu. Collected data were analyzed using t-test, paired t-test, ANOV A, Scheffe's test, and hierarchical multiple regression. Findings of this study are as follows: 1. School-aged children perceived that their maternal grandmothers rendered more emotional and informational support than their paternal grandmothers. 2. Paternal grandmother's social support as perceived by the grandchild varied significantly with the frequency of face-to-face contact, the frequency of phone contact, and the friendship between the paternal grandmother and the mother. Maternal grandmother's social support as perceived by the grandchild, on the other hand, varied significantly by the level of grandmother's education, the frequency of face-to-face contact, and the frequency of phone contact. 3. Perceived paternal and maternal grandmothers' social support had indirect impacts on grandchildren's depression, which was mediated by their mothers' parenting.

• 한국가족관계학회지
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• 제22권2호
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• pp.119-145
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• 2017

Objectives: Grounded in a life-course perspective, this study examined the effects of non-coresident children's transitions to marriage and parenthood on the frequency of contact with their parents. Gender of adult children and the educational levels of both adult children and their parents were evaluated as potential moderators of the transition-contact linkages. Method: The analytic sample consisted of adult children aged between 20 and 50 whose parents participated in four waves of the Korean Longitudinal Study of Ageing (2006, 2008, 2010, 2012). For analysis, fixed effects regression models were estimated using the xtreg procedure in Stata. Results: First, transition to marriage was associated with a decrease in face-to-face contact, whereas a greater increase in contact with parents via phone, mail, email etc. occurred only among newly married with less than college education compared to the newlywed with college degrees. Second, transition to parenthood was associated with an increase in contact via phone, mail, email etc. In addition, a greater increase in face-to-face contact was found with parents who completed high school or more education compared to those with less than high school education. Conclusions: The findings suggest that adult children's transitions to marriage and parenthood may bring about increases in contact with their parents, particularly for adult children with less than college education and parents with more than high school education.

• 한국멀티미디어학회논문지
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• 제24권1호
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• pp.125-133
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• 2021

Due to Covid-19, the un-contact culture has affected society as a whole, and the methods of education conducted offline has been greatly affected. In the private education of preparing for university entrance, the public official examinations and certification acquisition, the method of online education has been shown to have positive effects. While private class and school class which have offered in off-line to cope with rapid changes caused various problems such as decline in quality for education. Due to the characteristic of design class, practical training is important. As interactive feedback between students and educators is more important than one-way of delivering knowledge while class is conducted in online, educators have a challenge when they prepare for class. This study handles the methods of online education for the purpose of practical education methods in university nowadays, Especially, the non-face-to-face education methods for game animation production. Based on this study, I propose an effective educational method with non-face-to-face class that allows students to be satisfied and increases their knowledge, beyond face-to-face class.

• 한국항공운항학회지
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• 제32권2호
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• pp.124-134
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• 2024

This study is based on the Expectation Confirmation Theory (ECT) and categorizes trust types in non-face-to-face boarding services into three dimensions: structural assurance, platform, and service provider. It analyzes the impact of these trust types on users' perceived usefulness, satisfaction, and continuous usage intentions. Using a structural equation model, the study found that the three dimensions of trust positively influence users' satisfaction and perception of usefulness, thereby promoting intentions for continuous use. However, perceived risk weakens the positive relationship between trust and continuous usage intentions. By exploring the moderating role of perceived risk in non-face-to-face boarding services, this study analyzes its impact on user behavior patterns, contributing to the optimization of service design and enhancement of user trust. This study promotes widespread acceptance and continuous use of the service, and is crucial for developing effective non-contact service strategies that meet the needs and expectations of Chinese travelers in the post-pandemic travel environment. The findings provide a new perspective and empirical evidence for understanding user attitudes and behaviors towards non-face-to-face services, holding significant theoretical and practical implications.

• 한국공작기계학회논문집
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• 제15권3호
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• pp.32-38
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• 2006

During stereolithography processes, the shape errors such as curl distortion and distortion of side face are generated due to the shrinkage of liquid resins. In this study, the effects of dimension of part and structure of supports on the shape error are examined. Cubic specimens which have different thicknesses are manufactured and their deformations are measured with CMM. Thicker part generates smaller curl distortion of top face and larger of bottom face. Also thicker part generates larger distortion of side face until part thickness increases to about 20mm. Larger stiffness of supports which is obtained by shorter spacing of the supports and line type contact instead of point type contact generates smaller shape error of the part.

• 농업과학연구
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• 제45권2호
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• pp.283-289
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• 2018

Agricultural gear reducers are used in a variety of agricultural machinery designs such as in agricultural tractors and transport cars, and even greenhouses. For greenhouses, a gear reducer is used to control windows on the side and the roof. Gear reducers for agricultural applications are designed using the empirical method because of the lack of a standard for experimentation. Simulation is necessary for the optimal design of an agricultural gear reducer. There are many advantages to this optimization such as low-cost maintenance, reduced size, and weight. In this study, bending and contact safety factor simulation for the gear reducer of a greenhouse was conducted by decreasing the face widths of helical gear shaft 2 and shaft 3 from 30.8 and 30 mm, respectively, at an interval of 4 mm. The bending and contact safety factors were calculated using AGMA standard. Simulation results showed that bending and contact safety factors decreased rapidly when the face width of the helical gear on shaft 2 was 30 mm and the face width of helical gear on shaft 3 decreased from 30.8 mm to 26.8 mm, suggesting that it would be safe to reduce the face width of the helical gear on shaft 3 to 26.8 mm. The reduction of the face width also reduced the weight of the agricultural gear. This study suggests that the agricultural gear reducer safety factor decreases as the face width decreases.