• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.8B
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• pp.1028-1037
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• 2011

Recently, Selim et al proposed public key cryptography based privacy preserving multi-context RFID authentication protocol. However Selim et al's proposed protocol not only doesn't fit into passive tag based RFID system because it uses public key based encryption algorithm to perform authentication between reader and tag, but also is insecure to an impersonation attack because it doesn't provide mutual authentication. In order to eliminate the above described efficiency problem and security vulnerabilities, this paper proposes a new multi-context RFID mutual authentication protocol that can prevent privacy invasion and tag impersonation attack through providing mutual authentication between single passive tag which is located different application space and readers which provide multi-context purposes and can secure against relay attack and denial-of-service attack. As a result, the proposed protocol performs secure mutual authentication based on the collected space and time information from the RFID reader and provides strong security and high computation efficiency because if performs secure one-way hash function and symmetric encryption operations suitable to the environments of passive RFID tags.

• Journal of Institute of Control, Robotics and Systems
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• v.16 no.9
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• pp.860-865
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• 2010

This paper deals with gait assisting rehabilitation robot which helps SCI patient walk again. We propose new concept of orthotic for robot considering motions of Hip and Knee Joints, and how to fit the robot to a user in terms of weight balance and comfortable standing. Then we describe our first engineering sample being designed based on the passive orthotic and show how to make the robot work for SCI patient in basic operation.

• Journal of the Korean Society for Precision Engineering
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• v.20 no.1
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• pp.187-195
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• 2003

The performance of shock absorber is directly related to the car behaviour and performance, both for handling and ride comfort. The displacement sensitive shock absorber has two modes of damping force (i.e. soft and hard) according to the position of piston. In this study, a mathematical nonlinear dynamic model is introduced to predict the performance of displacement sensitive shock absorber. Especially in this paper, the transient zone is considered and the simulation result is well fit with experimental data. And the vehicle dynamic characteristic of displacement sensitive shock absorber is presented using quarter car simulation model. The simulation results of frequency response are compared with passive shock absorber.

• Korean Journal of Human Ecology
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• v.14 no.1
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• pp.1-13
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• 2005

This study has a purpose of developing a scale to evaluate maternal beliefs on preschool children's education. The subjects were 307 mothers of preschool children in Gwang-ju. The methods for data analyses included a factor analysis for construct validity, Pearson correlations between beliefs and learning-related activities for construct validity, and Cronbach's a for reliability. 4 factors were found, through literature review, in parental beliefs: passive learning, active learning, instruction, and expectation for academic-related skills acquisition. Factor analysis revealed that the 4-factor solution is the best fit. Correlations between beliefs and learning-related activities were statistically significant. Cronbach's a ranged from .65 to .87 for 4 sub-scales. It was concluded that the maternal beliefs scale is acceptable for use.

• Transactions of the Korean Society of Mechanical Engineers
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• v.19 no.2
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• pp.537-547
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• 1995

Numerical study on the chaotic stirring of viscous flow in an alternately driven cavity has been performed. Even under the Stokes-flow assumption, the inherent singularity at the corners made the problem not so easily accessible. With some special treatments to the region near the corners, the biharmonic equation was solved numerically by using the fully implicit method. The velocity field was then used in obtaining the trajectories of passive particles for studying the stirring effect. The three tools developed in the field of the nonlinear dynamics and chaos, that are the Poincare sections, the unstable manifolds, and the Lyapunov exponents, were used in analysing the stirring effect. It was shown that the unstable manifolds obtained in this study well fit the experimental results given by the previous investigators. It is predicted that the best stirring can be obtained when the aspect ratio a is near 0.8 and the dimensionless period T is in the range 4.3 - 4.7.

• International journal of advanced smart convergence
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• v.9 no.1
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• pp.163-171
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• 2020

There are many differences in narrative delivery between common movies and Virtual Reality(VR) films due to their differences in the appreciation structure. In VR films, scene changes by cuts have hindered the immersion of the audience instead of promoting narrative delivery. There are a range of experiments on narratives and immersion to solve this issue in VR films. Floating Tent applies hand gestures and immersive effects found in game elements and does not disturb narrative delivery by setting proper spaces and employing a direction technique to enable the melting of narratives into the characteristics of the spaces. There are time limits to offsound and mission performance, and devices fit for apocalyptic spatial expressions are made through a program. One of measures for the increasingly growing interactive storytelling in VR films is effective immersion. In narrative delivery, it is important to consider spatial setting and immersion to enable active intervention into events for immersion rather than passive audience only supposed to watch characters' acting.

• Proceedings of the KSR Conference
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• 2005.11a
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• pp.811-815
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• 2005

Traditional passive suspension has limitations to meet the required specifications of high level trains, and so Active suspension system is proposed to meet the requirements with active components which could be controlled by external signal for optimized behavior of train. Active suspension is to be divided by Full active suspension and Semi-active suspension whether using the external power source or not, and though the performance of Semi-Active suspension is worse than Full one. Semi-active suspension is focused with its effectiveness per cost. Semi-Active suspension system consists of sensors, ECU (electrical control unit), and variable damper, which are to be designed to be fit for train system. And the software of ECU is to be developed for to be suited to its dynamic behavior through simulation result calculated by proven model. In this experimental study, the hardware and software of semi-active suspension system is to be realized and its performance for improvement of ride quality to be confirmed through roller rig test.

• Proceedings of the KSR Conference
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• 2002.10a
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• pp.553-558
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• 2002

The harmonics in railway high voltage system is due to common use of 3 phase incoming bus and doing the power converter for traction system on the electric car(or electric locomotive). This paper, we analyze the harmonics mechanism and characteristics of railway high voltage system, also we analyze the problem according to the actual measurement about influence of harmonicsontherailwayhighvoltagesystem. And we proved the countermeasure device(passive filter or L-C filter) of harmonics applies in the field. The test result, we have know that the filter is not fit. Consequently, The countermeasure of harmonics for the railway high voltage system be able to resolve by another filter.

• Culinary science and hospitality research
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• v.23 no.3
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• pp.89-99
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• 2017

The purpose of this study is to examine the effects of foodservice employees' workplace harassment on their coping styles and intention to leave. Based on total 374 foodservice employees obtained from the empirical research, this study reviewed reliability and fitness of research model and verified total 3 hypotheses. SEM was conducted to test the validity of the proposed model and the hypotheses. The structural model provided an adequate fit to the data, $x^2=1,344.862$ (p<.001), df=420, GFI=.839, IFI=.900, CFI=.900, RMSEA=.076. To examine how employees' workplace harassment affects coping with harassment; workplace harassment had a significant effect on self-doubt (${\beta}=.401$, p<.001), ignored bully doubt (${\beta}=.621$, p<.001), and indirect or passive doubt (${\beta}=.527$, p<.001); whereas problem solving (${\beta}=-.094$, p>.05) did not. Furthermore, employees' workplace harassment (${\beta}=.126$, p<.05) had no significant effect on intention to leave. Employees' coping with harassment had a significant effect on intention to leave; especifically, among employees' coping with harassment elements, problem solving(${\beta}=-.572$; p<.001), self-doubt (${\beta}=.369$, p<.001), indirect or passive (${\beta}=.239$, p<.001), and ignored bully (${\beta}=-.161$, p<.01) had a significant effect on intention to leave. Limitations and future research directions are also discussed.

• Journal of The Korean Astronomical Society
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• v.52 no.5
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• pp.181-205
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• 2019

There is evidence that the luminosities of Type Ia supernova (SN Ia) depend on their environments. While the impact of this trend on estimating cosmological parameters is widely acknowledged, the origin of this correlation is still under debate. In order to explore this problem, we first construct the YONSEI (YOnsei Nearby Supernova Evolution Investigation) SN catalog. The catalog consists of 1231 spectroscopically confirmed SNe Ia over a wide redshift range (0.01 < z < 1.37) from various SN surveys and includes light-curve fit data from two independent light-curve fitters, SALT2 and MLCS2k2. For a sample of 674 host galaxies, we use the stellar mass and the star formation rate data in Kim et al. (2018). We find that SNe Ia in low-mass and star-forming host galaxies are $0.062{\pm}0.009mag$ and $0.057{\pm}0.010mag$ fainter than those in high-mass and passive hosts, after light-curve corrections with SALT2 and MLCS2k2, respectively. When only local environments of SNe Ia (e.g., locally star-forming and locally passive) are considered, this luminosity difference increases to $0.081{\pm}0.018mag$ for SALT2 and $0.072{\pm}0.018mag$ for MLCS2k2. Considering the significant difference in the mean stellar population age between the two environments, this result suggests that the luminosity evolution of SNe Ia with redshift is most likely the origin of the environmental dependence.