• Journal of the Korean Home Economics Association
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• v.47 no.2
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• pp.81-95
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• 2009

The purpose of this study is to examine gender equity in the quantity and flow experience of leisure time of urban dual-earner couples having preschool children. The quantity of leisure time is measured by primary activity and the flow experience of leisure time is measured by primary and secondary activities. The data collected by Korean National Statistical Office in 2004 is used. The sample for this study consists of 255 couples, and the statistical methods are frequency, percentage, paired t-test, and one-way ANOVA. The following is a summary of the major findings. The first, the pattern of the leisure time was different between husbands and wives. The quantity of leisure time of husbands was longer than that of wives. The husbands spent more time to perform social activities, media contact, sports and outdoor activities, while women did more in religious activities. The second, husband's leisure flow experience was higher than that of wives. The pure leisure time of wives was shorter than that of husbands and wives experienced more contaminated leisure time by a secondary activity. In other words, wives's leisure is more likely to be interrupted, to involve episodes of shorter duration, and to be associated with personal care and unpaid work.

• International Journal of Automotive Technology
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• v.5 no.4
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• pp.247-255
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• 2004

The majority of real world frontal collisions involves partial overlap (offset) collision, in which only one of the two longitudinal members is used for energy absorption. This leads to dangerous intrusions of the passenger compartment. Excessive intrusion is usually generated on the impacted side causing higher contact injury risk on the occupants compared with full frontal collision. The ideal structure needs to have extendable length when the front-end structure is not capable to absorb crash energy without violating deceleration pulse requirements. A smart structure has been proposed to meet this ideal requirement. The proposed front-end structure consists of two hydraulic cylinders integrated with the front-end longitudinal members of standard vehicles. The work carried out in this paper includes developing and analyzing mathematical models of two different cases representing vehicle-to-vehicle and vehicle-to-barrier in full and offset collisions. By numerical crash simulations, this idea has been evaluated and optimized. It is proven form numerical simulations that the smart structures bring significantly lower intrusions and decelerations. In addition, it is shown that the mathematical models are valid, flexible, and can be used in an effective way to give a quick insight of real life crashes.

• Journal of computational fluids engineering
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• v.21 no.4
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• pp.90-95
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• 2016

Leidenfrost drops with ellipsoidal shaping can control the bouncing height by adjusting the aspect ratio(AR) of the shape at the moment of impact. In this work, we focus on the effect of the AR and the impact Weber number(We) on the non-axisymmetrical spreading dynamics of the drop, which plays an important role in the control of bouncing. To understand the impact dynamics, the numerical simulation is conducted for the ellipsoidal drop impact upon the perfect non-wetting solid surface by using volume of fluid method, which shows the characteristics of the spreading behavior in each principal axis. As the AR increases, the drop has a high degree of the alignment into one principal axis, which leads to the consequent suppression of bouncing height with shape oscillation. As the We increases, the maximum spreading diameters in the principal axes both increase whereas the contact time on the solid surface rarely depends on the impact velocity at the same AR. The comprehensive understanding of the ellipsoidal drop impact upon non-wetting surface will provide the way to control of drop deposition in applications, such as surface cleaning and spray cooling.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.06a
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• pp.1549-1554
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• 2000

HDD structure is excited by the dynamic motion of disk-spindle motor components. Those excitations which are generated at stator and magnet rotor, at bearings and from disk dynamics, are transmitted through motor spindle and flange to HDD cover and base. The operational deflection shape measurement can show the structural excitation patterns at the most influent frequency on the acoustic noise level. One of those components is the axial excitation along spindle, and the other is the local orbital excitation at contact area of motor flange and base. To make a reduction of those structural transmission excitations, the structure of spindle motor is modified to the direction of reinforcement at transmission path without change of bearings, magnet and coil. Some excitation of spindle motor component carrying out essential function is unavoidable. So it is the efficient way of HDD noise improvement to control the structural transmission of excitation.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.2317-2318
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• 2008

This report is about wireless energy transform system. It means something to charge without a line of contact. Existing charging has been many defect, including badness of the line, limitation of the space and the time and so on But this is one of the way that can complement it. So our goal is making the wireless charger that is effective and easy to use.

• Geomechanics and Engineering
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• v.16 no.3
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• pp.309-320
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• 2018

In this paper, a numerical study using finite element method with considering soil-structure interaction was conducted to investigate the stress and deformation behavior of a sheet pile wall structure. In numerical model, one of the nonlinear elastic material constitutive models, Duncan-Chang E-v model, is used for describing soil behavior. The hard contact constitutive model is used for simulating the behavior of interface between the sheet pile wall and soil. The construction process of excavation and backfill is simulated by the way of step loading. We also compare the present numerical method with the in-situ test results for verifying the numerical methods. The numerical analysis showed that the soil excavation in the lock chamber has a huge effect on the wall deflection and stress, pile deflection, and anchor force. With the increase of distance between anchored bars, the maximum wall deflection and anchor force increase, while the maximum wall stress decreases. At a low elevation of anchored bar, the maximum wall bending moment decreases, but the maximum wall deflection, pile deflection, and anchor force both increase. The construction procedure with first excavation and then backfill is quite favorable for decreasing pile deflection, wall deflection and stress, and anchor forces.

• Journal of Korean society of Dental Hygiene
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• v.17 no.4
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• pp.613-620
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• 2017

Objectives: The purpose of this study is to investigate the antibacterial effect of Streptococcus mutans of tea tree ingredient. Methods: The experimental groups were each given with different concentrations (30 or 50 vol%) of tea tree prepared in saline solution. The control group applied only saline solution. The tea tree coating of the specimen were examined under a scanning electron microscope. For the antibacterial activity test of the tea tree, the contact angle of the tea tree- coated specimen's surface was analyzed. The antibacterial effect against Streptococcus mutans was determined by counting the colony forming units (CFU). The statical statics were evaluated by using one-way ANOVA and paired t-test. Results: The tea tree treated group of hydrophilic more than non treated group. Antibacterial experiments demonstrated that tee tree solution was effective against Streptococcus mutans. However there was no significant difference in depending solution concentration groups. Conclusions: The antimicrobial activity of the tea tree containing solution showed its potential for use as coating for denture and medical materials.

• Fashion & Textile Research Journal
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• v.12 no.1
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• pp.109-113
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• 2010

Since July 2007, the government has banned the use of the existing non-legal measurement units, and has forced us to use the unified legal measurement. Therefore, the existing clothing size unit also has been changed into centimeter dimensions from inches. However, consumers have been familiar to used to the traditional inches unit. So they have the confusion to directly survey the size table sign for clothing or to contact the employee when purchasing clothing. By the current size table sign the customers can compare the inches unit and centimeters unit, but they are difficult to see it. Therefore, there is necessary to improve the size table sign by the way that can be easy to be found and seen by consumers is given to the clothing corners. In this research, three improved size table signs were developed. And they were evaluated by the consumers in terms of preferences and awareness of them. Eventually, the best size table sign was selected. From this result, if the large-discount mart use the best improved size table sign on behalf of the current one, the problems of existing size table sign will overcome and improve customer satisfaction.

• Transactions of the Korean Society of Automotive Engineers
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• v.19 no.3
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• pp.113-121
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• 2011

Rollover accident is one of the serious traffic accident and rollover accident takes high portion of all accident. The most common type of rollover is a tripped rollover which occupy 95% of all type of single-vehicle rollover. Tripped rollover occurs when a vehicle leaves normal road way and tripped by loose gravel, soil of fixed object such as guard rail, curbs and ditches. And the rest of the type of rollover is un-tripped rollover. An un-tripped rollovers that occurs during high-speed collision avoidance maneuvers. In this paper, presents the explanation of the un-tripped rollover test method and procedure, additionally this paper deals with various occurrence in the un-tripped test such as occurring excessive tire camber in the un-tripped test, tire side-wall contact with road surface and roll oscillation. And this paper analyzes the analysis of the roll rate amplitude in specific frequency through the FFT (Fast Fourier Transform) and the roll angle at the steering reverse timing which is the Fishhook test roll rate feedback time. Finally, this paper analyzes the relations between the estimated steady state roll gain and rollover stability.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2016.05a
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• pp.467-469
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• 2016

Car smart key system is a technology that allows you to turn activate / deactivate the auto lock through the contact form of electronic keys on the remote control and turn on the ignition by pressing the button. Smart key system is regarded as one of the essential options of the car as it is increasingly convenient to user, but there is no response yet for an attack to this situation. Therefore, in this paper, through an analysis of the amplification attack of a smart key we propose a way to stop the amplification attack and stop the car seized in case the car door opened due to the amplification attack.