• Composites Research
• /
• v.31 no.4
• /
• pp.156-160
• /
• 2018

In this paper, evaluation method of structural integrity for cone-type composite lattice structures with hexagonal cell was conducted. A finite element analysis was used to evaluate the structural integrity of cone-type composite lattice structure. The finite element model for evaluation of structural integrity was generated using solid element. In order to consider the difference in mechanical properties between intersection and non-intersection part, the mechanical properties were applied considering the fiber volume fraction of each part. Compression test of cone-type composite lattice structure were conducted for verification of evaluation method of structural integrity. The analysis result showed 2% errors in displacement and good agreement with test result.

• Analytical Science and Technology
• /
• v.8 no.2
• /
• pp.205-213
• /
• 1995

Counter-diffusion of coronene desorbed from alumina with addition of tetra-phenylporphine was studied by spectrophotometry. The counter-diffusion processes of adsorbing and desorbing materials in liquid phase were simulated by counter-diffusion model based on Fritz's binary component isotherm under an assumption of equimass diffusion. The counter-diffusivities of desorbed coronene with addition of tetra-phenylporphine were as ${\sim}10^{-15}m^2/sec$ and that of adsorbed tetra-phenylporphine as ${\sim}10^{-11}m^2/sec$. The counter-diffusivity of coronene determined from desorption process was smaller by ${\sim}10^5$ times than the diffusivity determined from adsorption process of a single species. The reduction of the determined counter-diffusivity of coronene in desorption process was explained by the cross of diffusion fluxes and build-up of high gradient of coronene in pore.

• International Journal of Highway Engineering
• /
• v.14 no.2
• /
• pp.83-91
• /
• 2012

This study deals with the operational efficiency of roundabout. The roundabouts generally have such the merits as high capacity, delay reduction, safety improvement, and others. Circular intersection can be divided into the rotary and roundabout according to travelling priority. The objective of this study is to comparatively analyze the operational efficiency of rotary and roundabout by scenario. In pursuing the above, this study gives the particular attentions to developing 256 scenarios according to the directional and entering traffic volume and analyzing the delay using VISSIM. The main results are as follows. First, the average delay of rotary was analyzed to be 1.56-8.74 times of roundabout. Second, the operational efficiencies of rotary and roundabout were analyzed to be better in the case of bigger differences in the traffic volumes between the main and minor roads. Third, the average delay of the 4-legged was evaluated to be 1.77-11.70 times of 3-legged intersection. Finally, 2-lane intersection (3-legged & 4-legged) was analyzed to be 2.02-2.23 times of 1-lane intersection.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.39 no.11
• /
• pp.995-1004
• /
• 2011

Object X-ray method commonly used for hole search in overset grids requires huge amount of time due to complicated vector calculations to search the cross-points as well as time-consuming hole search algorithm with respect to background grids. Especially, when the grid system is in motion relative to the background, hole points should be searched at every time step, leading to hung computational burden. To cope with this difficulties, this study presents an efficient hole search algorithm mainly designed to reduce hole searching time. To this end, virtual surface with reduced grid points is suggested and logical operators are employed as a classification algorithm instead of complicated vector calculations. In addition, the searching process is further accelerated by designating hole points in a row rather than discriminating hole points with respect to each background grid points. If there exists a relative motion, the present algorithm requires much less time because only the virtual surface needs to be moved at every time step. The hole searching time has been systematically compared for a few selected geometries.

• Journal of the Korea Society of Computer and Information
• /
• v.12 no.2 s.46
• /
• pp.63-70
• /
• 2007

The Data Encryption Standard (DES) is a block cipher that encrypts a 64 bit block of plaintext into a 64 bit block of ciphertext. The DES has been a worldwide standard for 20 years since it was adopted in 1976. strong. But, due to the rapid development of hardware techniques and cryptanalysis, the DES with 64-bit key is considered to be not secure at the present time. Therefore it became necessary to increase the security of DES. The NG-DES(New Generation DES)[1] is an encryption system which upgrades the encryption security of DES by the key extension and the usage of non-linear f function. It extends not only the size of plaintext and ciphertext to 128 bit but also the Fiestel structure used in each round. This structure has a weak point that the change of each bit of plaintext does not affect all bits of ciphertext simultaneously. In this paper, we propose a modified Fiestel structure of DES and thus increased confusion and diffusion by effectively cross-connecting between outputs in a round and inputs in next round.

• International Journal of Highway Engineering
• /
• v.10 no.4
• /
• pp.53-63
• /
• 2008

Even though accident frequencies in roadway segments have been decreasing since 2000, there has been increasing the number of vehicle crashes at intersections. Due to this increase, safety problems at intersection recently started to be regarded as significant issues. The purpose of this study is to analyze the effects of road conditions, traffic operational conditions, and other influencing condition on intersection safety. Then a traffic accident frequency prediction model to evaluate the safety at intersections was developed based on the correlations between influencing factors and vehicle crashes. In this research, critically significant factors affecting vehicle crashes at rural four-legs signalized intersections were investigated. It was found that Poisson regression was the best fit method to developing a accident frequency modeling using the collected data in this study. Through this study, it was concluded that exclusive left turn lane, crosswalk, posted speed, lighting, angle, and ADT are significant influencing factors on the intersection safety.

• Fire Science and Engineering
• /
• v.30 no.3
• /
• pp.124-132
• /
• 2016

Medical oversight (MO) means the advice and direction provided by a physician to rescue workers who provide medical care or carry patients at the scene of an emergency. The purpose of this study was to investigate the utilization of MO and related factors among some 119 rescue workers in Gwangju. A self-reported questionnaire was completed by 153 rescue workers in these 119 safety centers. The data were analyzed by SAS version 9.3. Overall 82.4% of the subjects utilized MO during the past month. In the multiple logistic regression analysis, the married subjects (OR = 3.87, 95% CI = 1.22~12.27), level 1 emergency medical technicians (OR = 2.87, 95% CI = 1.02~8.09), and subjects who treated cardiovascular emergency patients (OR = 9.19, 95% CI = 1.87~45.08) had significantly higher odds ratios for the utilization of MO. The experience of MO accounted for 82%. The development of strategies and education plans taking these results into consideration will help to improve the utilization of MO.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.34 no.9B
• /
• pp.847-856
• /
• 2009

In geographic routing for wireless sensor networks, sources need the location of sinks destined for delivering their data packets. Most of the existing geographic routing protocols merely assume that the sources can get the locations of sinks by some location service. How source nodes find out the location of sinks is not easy. In this paper, we propose a sink location dissemination scheme in geographic routing for wireless sensor networks. In this scheme, a source node and a sink node send sink location announcement and query messages along two paths respectively by geographic routing. The node located on the crossing point of the two paths informs the source about the sink location. Then the source can send data packet to the sink by geographic routing. How to guarantee that these two paths have at least one crossing point in any irregular profile of sensor network is the challenge of this paper Simulation results show that our protocol is significantly superior to other protocols in terms of energy consumption and control overhead.

• The Journal of The Korea Institute of Intelligent Transport Systems
• /
• v.16 no.4
• /
• pp.64-75
• /
• 2017

Previous count models using fixed parameter can not consider the unobserved heterogeneity, as the standard error of the count value is underestimated, excessive t-values are derived thereby reducing the reliability of the model. Also, the study of unsignalized intersections are inadequate because of the difficulty of collecting data and statistical limits for accurate analytical processes compared to the signalized intersections. The purpose of this study is to analyze the factors affecting traffic accidents by constructing the count model using random parameters, and it aimed to distinguish between existing studies based on the rural unsignalized intersections. As a result of the analysis, 7 variables were presented as significant variables, and 2 variables(presence of crosswalk, speed limit) were presented as random parameter.

• Journal of Digital Convergence
• /
• v.14 no.12
• /
• pp.667-675
• /
• 2016

This study aims to investigate the effects of regular participation in physical activity on personal happiness by analyzing the "2014 National Leisure Sports Participation Survey". By using cross-tabulation and the binary logit model, it is found that there is a positive correlation between those two variables. The effect of positive affect on happiness index was found to be influenced by age, education level, occupation, income, marital status, appear. The results of the analysis of the relationship between the presence of sports facilities and the participation of regular physical activity using crosstab analysis and the analysis of physical activity showed positive relationship between two variables. Hence, it is expected that providing more opportunities to participate in sports programs can lead the public to more regular participation in physical activity.