• Proceedings of the KIEE Conference
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• summer
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• pp.1166-1168
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• 2004

The high frequency series resonant converter has been widely used for the non-contact power supply system with the large air gap and the increased leakage inductance of the non-contact transformer. However. the high frequency series resonant converter has the disadvantages of high voltage gain characteristics in the overall load range due to the large air gap and the circulating magnetizing current. In this paper, unit voltage gain is revealed in the proposed three-level series-parallel resonant converter. The results are verified on the simulation results and the 5kW experimental prototype.

• Journal of Family Relations
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• v.22 no.2
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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.

• Journal of Korean Ophthalmic Optics Society
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• v.9 no.1
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• pp.145-159
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• 2004

A mathematical model and its computer solution program were proposed to analyze the motion of contact lenses which are being subject to lid-blinking. The equation was derived by incorporating an acceleration induced lid's force exerting on the contact lens, the viscous damping resistance in the tear layer beneath the lens and the sliding frictional force between the lid and the contact lens surface into the formulation of differential equation describing the vibration. The model predicts the time-dependent displacement from the equilibrium postion during/after the blinking. During the blinking, as the time for the completion of one cycle of blinking decreases the off-the-equilibrium displacement of contact lens increases while the decrease of diameter in the contact cause the opposite effect. It is found that lid pressure exerting on the lens cause an insignificant lens displacement from the equilibrium position. After blinking the frequency of damped oscillation of contact lens decreases as the diameter of lens increases, due to the incresed surface while the reduced blinking time does not cause a significant frequency change. This is because that driving force for the contact lens movement posterior to blinking is the capillary-induced force not the lid force.

• Journal of Agricultural Extension & Community Development
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• v.3 no.1
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• pp.83-93
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• 1996

This study examines the agricultural extension agents` satisfaction with their job and its related variables - personal characteristics, achievement motivation, and needs level. Based on die Job Descriptive Index, Brayfield-Rothe Index, and Porter Instrument, the survey was carried out on 127 agents. Results show 1) a significant difference in personal characteristics is found in position, farmer contact frequency, and service region applied for, but not in age, gender, scholastic ability, career, task, and another department contact frequency, 2) the achievement motivational level is related to job satisfaction, and 3) the needs level is not related to job satisfaction.

• International Journal of Advanced Culture Technology
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• v.10 no.3
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• pp.263-271
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• 2022

The purpose of this study is to identify the degree of participation and the impact of social media sports contact motivation on sports activities. In order to clarify the purpose of this study, a total of 300 students from 150 male and 150 female university students in Gwangju and Jeonnam provinces in 2020 were selected by the convenience sampling method. The survey tool used to achieve the purpose of this study is the questionnaire method. Therefore, the questionnaire, which has already been verified for reliability and validity in domestic and foreign previous studies, was re-quoted, modified, or supplemented for the purpose of this study. For data processing, SPSS Windows 20.0 Version was used. For specific statistical analysis, frequency analysis, exploratory factor analysis, reliability analysis, and multiple regression analysis were performed according to the purpose of analysis. The results obtained through these results are as follows. First, it was found that the contact motivation for social media sports partially affected the degree of participation in social media sports. Second, it was found that social media sports contact motivation has a partial influence on sports participation. Third, the degree of social media sports participation was found to have a partial influence on sports participation.

• Tribology and Lubricants
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• v.36 no.5
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• pp.290-296
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• 2020

When two layers of carbon nanotube (CNT) arrays are loaded to mate, the free ends of individual CNTs come into contact at the interface of the two layers. This leads to a higher contact resistance due to a smaller contact region. However, when the free CNT ends of one array penetrate into the mating array, the contact region increases, effectively lowering the contact resistance. To explore the penetration of mating CNTs, we perform molecular dynamic simulations of a simple unit cell model, incorporating four CNTs in the lower array layer coupled with a single moving CNT on the upper layer. The interaction with neighboring CNTs is modelled by long-range carbon bond order potential (LCBOP I). The model structure is optimized by energy minimization through the conjugate gradient method. A NVT ensemble is used for maintain a room temperature during simulation. The time integration is performed through the velocity-Verlet algorithm. A significant vibrational motion of CNTs is captured when penetration is not available, resulting in a specific vibration mode with a high frequency. Due to this vibrational behavior, the random behaviors of CNT motion for predicting the penetration are confirmed under the specific gap distances between CNTs. Thus, the probability of penetration is examined according to the gap distance between CNTs in the lower array and the aspect ratio of CNTs. The penetration is significantly affected by the vibration mode due to the van der Waals forces between CNTs.

• Transactions of the Korean Society of Automotive Engineers
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• v.15 no.4
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• pp.115-123
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• 2007

In this paper, an analytical model is developed to describe the dynamic characteristics of a roller bearing. In order to obtain accurate dynamic response of roller bearing, each roller is modeled as a rigid body, which has radial and axial movement and rotational constraints. Beam element between outer race segments is used to consider flexibility of outer race. Beam deflection is calculated from beam forces and used for contact between roller and outer race. The efficient contact search kinematics and algorithms in the context of the compliance contact model are implemented to detect the interactions between roller and race for the sake of speedy and robust solutions. The numerical results are validated with another analysis results which are calculated using waviness condition. Increasing rollers, dynamic responses are compared with each other. In order to confirm dynamic behavior and nonlinear characteristic of roller bearing, Poincare map is used.

• Tribology and Lubricants
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• v.33 no.6
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• pp.303-308
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• 2017

Most automobile tire companies have not yet considered the geometric information of a road at the design stage of a tire because the topographical characterization of a road surface is very difficult owing to its vastness and randomness. A road surface shows variable surface roughness values according to magnification, and thus, the contact force between the road and tire significantly fluctuates with respect to the scale. In this study, we make an attempt to define a representative value for surface topographical information at multi-scale levels. To represent surface topography, we use a statistical method called power spectral density (PSD). We use the fast Fourier transform (FFT) and PSD to analyze the height profiles of a random surface. The FFT and PSD of a surface help in obtaining a fractal dimension, which is a representative value of surface topography at all length scales. We develop three surfaces with different fractal dimensions. We use finite element analysis (FEA) to observe the contact forces between a tire and the road surfaces with three different fractal dimensions. The results from FEA reveal that an increase in the fractal dimension decreases the contact length between the tire and road surfaces. On the contrary, the average contact force increases. This result indicates that designing and manufacturing a tire considering the fractal dimension of a road makes safe driving possible, owing to the improvement in service life and braking performance of the tire.

• Research in Community and Public Health Nursing
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• v.14 no.3
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• pp.468-478
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• 2003

Purpose: The purpose of this study is to identify the relationship among sexual contact, sex role identification, and self esteem in Korean girls' high school students. Methods: The data were collected from 522 girls, who were stratified samples from a target population of 63,375 11th grade students from 200 regular high schools and 70 vocational high schools in Seoul, Korea from June 22 to July 18, 2002. Data were processed with the SAS program. Results: It was found that 42.51% of girls haven't experienced any sexual contact at all. The highest frequency in the final level of sexual contact was 'kiss', which was 22.03%. The 'androgyny' type among sex role identities of girls was most common, 32.57%, being followed by the 'undifferentiated' type 31.61%, the 'masculinity' type 18.97%, and the 'femininity' type 16.86, in that order. The sexual contacts such as 'holding hands', 'arms around', 'embracing', and 'kiss' were significantly different depending on sex role identity types. The score for self-esteem was significantly different depending on sex role identity types. The score for self- esteem was not significantly different depending on the final level of sexual contact. Conclusion: Based on the findings of this study, sex education programs should be developed in order to delay the sexual contacts of girls.

• Korean Journal of Adult Nursing
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• v.19 no.4
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• pp.634-643
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• 2007

Purpose: This study was performed to investigate the type and frequency of end colostomy-related complications and to identify the risk factors for those complications. Methods: Retrospective analysis of medical records was made in 708 patients who underwent end colostomy in Samsung Medical Center between October 1994 and February 2005. The type was divided into stomal and peristomal complications: stomal complications included bleeding, necrosis, mucocutaneous separation, prolapsed stoma, retraced stoma, stenosis, and hyperplasia; peristomal complications did peristomal varix, peristomal hernia, irritant contact dermatitis, allergic contact dermatitis, maceration, folliculitis, hyperplasia, bacterial infection, candidal infection, malignancy in the peristomal area, mechanical damage and pyoderma gangrenosum. Results: For stomal complications, hyperplasia was most common(9.0%). For peristomal complications, irritant contact dermatitis was developed in 17.4%. Sex and BMI were risk factors for irritant contact dermatitis, hyperplasia, peristomal hernia, flat stoma, and retracted stoma. Conclusion: Teaching for preventing irritant contact dermatitis such as proper pouching and peristomal skin protection, and for comprehensive weight control should be emphasized on self care program for ostomates, while ostomy care nurse should take a careful consideration of preoperative ostomy site marking in female obese patients.