• Journal of Ocean Engineering and Technology
• /
• v.11 no.4
• /
• pp.249-261
• /
• 1997

A basic study on the lifting lug design has performed through the rational and systematic process. In order to evaluate the proper design-load distribution around lug eye investigation of contact force between lifting lug and shackle pin is performed using non-linear parametric analysis idealized by gap element models. Gap element modeling and nonlinear analysis procedures are illustrated and discussed based on MSC/NASTRAN. Some analysis and design guides are suggested through the consideration of several important effects such as stress distribution pattern, circumferential contact force distribution along the lug eye face, loading share rate between lug main plate and doubler, effect of loading direction, relation between applied force and deflection and size effect of shackle pin radius. Additionally optimum design studies are performed and general trends according to the variation of design parameters are suggested.

• Journal of Mechanical Science and Technology
• /
• v.16 no.4
• /
• pp.492-500
• /
• 2002

This paper presents a study of the effect of varying the roll gap of oval pass in round-oval-round pass sequence on the interracial slip of workpiece, entrance and exit velocities, stresses and roll load that the workpiece experiences during rolling, by applying analytical method, finite element simulation and verification through hot bar rolling tests. The results have shown that the roll gap variation of oval pass affects the interfacial slip of workpiece along the groove contact and the specific roll pressure. The optimum conditions in terms of minimum interfacial slip and minimum specific roll pressure, which might influence the maximum groove life, is obtained when the subsequent round pass is completely filled.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2001.11b
• /
• pp.597-600
• /
• 2001

In order to investigate the electrical properties of X-ray tube oils for insulating and cooling, the breakdown characteristics in temperature range of $20\sim100[^{\circ}C]$, that of AC breakdown in 0.5~2.5[mm] of gap length, we are made researches. The classification for the physical properties of oil for X-ray tube by FTIR and H-NMR experiments was confirmed to type of mineral oils. As for the dependance of breakdown characteristics due to electrode gap length, breakdown voltage was found nearly uniform by impurity effect according to the increase of gap. As a result the characteristics for AC breakdown, the dielectric strength was increased to $90[^{\circ}C]$ but decreased over $90[^{\circ}C]$ in the temperature range.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2003.11a
• /
• pp.1095-1100
• /
• 2003

Experimental studies on the aerodynamic coupling effect on natural frequencies, critical speed and flutter instability of DVD disks are investigated in this paper. The experimental results are compared with the theoretical analyses where the aerodynamic effects are represented in terms of elastic, lift and damping and stiffness components. The experiments are performed using a vacuum chamber and DVD disks rotating in vacuum, open and enclosure with several different gaps between disk and wall. The following three results are given. One is that the aerodynamic effect by the surrounding air reduces the natural frequencies and critical speeds of the vibration modes. The second is that natural frequency decreases as the disk-wall gap is decreased. Finally, it is shown that the disk vibration is reduced as the gap between the disk and the rigid wall decreases.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 1994.10a
• /
• pp.975-979
• /
• 1994

The experimental and finite element studies of a coaxial cylindrical shell filled with liquid in the annular gap were performed to understand its vibration characteristics. Finite element analysis was achieved by using ANSYS code. Form the investigation of the changing trend of natural frequencies for the change of annular gap we know that the natural frequency of the coaxial cylindrical shell varies according to the mode shape. that is, in case of in-phase mode the natural frequency decrease as annular gap increase, but in case of out-of-phase mode the natural frequency increase. Finite element analysis results show the excellent agreement with the experimental results both in air and in water case, so that analysis on other cases with be possible without experiment.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2001.11a
• /
• pp.597-600
• /
• 2001

In order to investigate the electrical properties of X-ray tube oils for insulating and cooling, the breakdown characteristics in temperature range of 20∼100[$^{\circ}C$], that of AC breakdown in 0.5∼2.5(mm) of gap length, we are made researches. The classification for the physical properties of oil for X-ray tube by FTIR and $^1$H-NMR experiments was confirmed to type of mineral oils. As for the dependance of breakdown characteristics due to electrode gap length, breakdown voltage was found nearly uniform by impurity effect according to the increase of gap. As a result the characteristics for AC breakdown, the dielectric strength was increased to 90[$^{\circ}C$] but decreased over 90[$^{\circ}C$] in the temperature range.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.25 no.5
• /
• pp.79-84
• /
• 2011

In this study, breakdown characteristics of a vertical sphere-plane air gap in the presence of combustion flame were examined under the application of a.c. and d.c. high-voltages in order to investigate the effect of flame on the dielectric strength of air. Propane gas is used as the fuel of the flame, and the temperature distribution of air around the flame is measured. The polarity effects for the d.c. voltages and breakdown voltages of air when applied both of a.c. and d.c. voltages were examined in the case of the variation of the gap length and the horizontal distance between the flame and the high-voltage sphere electrode. The influence of relative air density, electrification and shape changes of the flame as factors that affect the breakdown voltages were discussed.

• The Journal of the Acoustical Society of Korea
• /
• v.30 no.4
• /
• pp.223-230
• /
• 2011

Korean bell is hung with some air gap between the bell bottom and the ground. In addition, it has a peculiar acoustic element, so called resonance cavity below the bell. A proper design of the air gap and cavity size dramatically amplifies the bell sound by resonance effect. Bell interior cavity, air gap and resonance cavity consist of an acoustic cavity system. When the acoustic cavity frequency coincides with the natural frequency of the bell body, the frequency component is significantly amplified. On the Sacred Bell of the Great King Seongdeok, this study proposes a resonance condition of the cavity system considering air gap effect for the first time. With the exact dimension of the bell, boundary element analysis is performed using SYSNOISE. Finally, this study reveals how the temperature in season influences the resonance condition and proposes a concept of variable type resonance cavity. By using the variable type resonance cavity, the cavity size is controlled on site and exact resonance is available regardless of temperature difference in season.

• Human Ecology Research
• /
• v.54 no.5
• /
• pp.487-498
• /
• 2016

The study was examined the multiple mediated effects of maternal self-efficacy and depression between perception gap about paternal involvement and marital conflict for dual-income parents. The data used were the fifth year data of the Panel Study on Korean Children from Korea Institute of Child Care and Education in 2012. The subjects consisted of 449 dual-income parents with more than one child. Data were analyzed using descriptive statistics, one-way analysis of variance, paired t -test, and correlation. SPSS macro and bootstrapping methods also assessed the mediation effects of maternal self-efficacy and depression between the perception gap about paternal involvement and marital conflict in dual-income parents. The results of this study were as follows. Significant positive correlations were observed for marital conflict, perception gap of dual-income parents about paternal involvement and maternal depression. Perception gaps by parents and self-efficacy were negatively correlated. Perception gaps by parents showed a direct effect on marital conflict. The results of indirect effects of all mediators showed the mediated effect of maternal self-efficacy and depression. The study revealed that the perceptive gap about paternal involvement has a significant impact on maternal self-efficacy and depression, as well as marital conflict. The perceptive gap of dual-income parents about paternal involvement has critical effects on marital conflict as much as the quantity of paternal involvement.

• Korean Educational Research Journal
• /
• v.37 no.1
• /
• pp.47-66
• /
• 2016

The purpose of this study is to examine the analysis on the effect of incentive gap of teacher's merit-pay on organizational commitment and organizational citizenship behavior. The study verified the hypothetical path model and analyzed the effects of incentive gap of teacher's merit-pay, organizational commitment and organizational citizenship behavior. The subjects of the study are 762 elementary and secondary school teachers. The results of the study are as follows: Firstly, it was found that there are significant correlations among incentive gap of teacher's merit-pay, organizational commitment and organizational citizenship behavior. Secondly, incentive gap of teacher's merit-pay affects organizational commitment and organizational citizenship behavior. Lastly, S grade teachers of teacher's merit-pay are more organizational commitment and organizational citizenship behavior level were higher than A and B grade teacher. Therefore teacher's merit-pay have positive impacts to the teachers.