• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.9 no.4
• /
• pp.1337-1358
• /
• 2015

In this paper, we present an analytical and simulated study on the performance of adaptive vehicular ad hoc networks (VANET) priority based on Transmission Distance Reliability Range (TDRR) and data type. VANET topology changes rapidly due to its inherent nature of high mobility nodes and unpredictable environments. Therefore, nodes in VANET must be able to adapt to the ever changing environment and optimize parameters to enhance performance. However, there is a lack of adaptability in the current VANET scheme. Existing VANET IEEE802.11p's Enhanced Distributed Channel Access; EDCA assigns priority solely based on data type. In this paper, we propose a new priority scheme which utilizes Markov model to perform TDRR prediction and assign priorities based on the proposed Markov TDRR Prediction with Enhanced Priority VANET Scheme (MarPVS). Subsequently, we performed an analytical study on MarPVS performance modeling. In particular, considering five different priority levels defined in MarPVS, we derived the probability of successful transmission, the number of low priority messages in back off process and concurrent low priority transmission. Finally, the results are used to derive the average transmission delay for data types defined in MarPVS. Numerical results are provided along with simulation results which confirm the accuracy of the proposed analysis. Simulation results demonstrate that the proposed MarPVS results in lower transmission latency and higher packet success rate in comparison with the default IEEE802.11p scheme and greedy scheduler scheme.

• The Journal of Korea Robotics Society
• /
• v.7 no.4
• /
• pp.259-266
• /
• 2012

In these days, researches about underwater robots have been actively in progress for the purposes of ocean detection and resource exploration. Unlike general underwater robots such as ROV(Remotely Operated Vehicle) and AUV(Autonomous Underwater Vehicle) which have propellers, an articulated underwater robot which is called Crabster has been being developed in KORDI(Korea Ocean Research & Development Institute) with many cooperation organizations since 2010. The robot is expected to be able to walk and swim under the sea with its legs. Among many researching fields of this project, we are focusing on a swimming section. In order to find effective swimming locomotion for the robot, we approached this subject in terms of Biomimetics. As a model of optimized swimming organism in nature, diving beetles were chosen. In the paper, swimming motions of diving beetles were analyzed in viewpoint of robotics for applying them into the swimming motion of the robot. After modeling the kinematics of diving beetle through robotics engineering technique, we obtained swimming patterns of the one of living diving beetles, and then compared them with calculated optimal swimming patterns of a robot leg. As the first trial to compare the locomotion data of legs of the diving beetle with a robot leg, we have sorted two representative swimming patterns such as forwarding and turning. Experimental environment has been set up to get the motion data of diving beetles. The experimental equipment consists of a transparent aquarium and a high speed camera. Various swimming motions of diving beetles were recorded with the camera. After classifying swimming patterns of the diving beetle, we can get angular data of each joint on hind legs by image processing software, Image J. The data were applied to an optimized algorithm for swimming of a robot leg which was designed by robotics engineering technique. Through this procedure, simulated results which show trajectories of a robot leg were compared with trajectories of a leg of a diving beetle in desired directions. As a result, we confirmed considerable similarity in the result of trajectory and joint angles comparison.

• The Korean Journal of Malacology
• /
• v.26 no.1
• /
• pp.1-18
• /
• 2010

Biological organisms produce organic-inorganic nanocomposite composites that are hierarchically organized in composition and microstructure, containing both inorganic and organic components in complicated mixtures. The process related to the generation and regeneration of organic-inorganic complex in nature is called biomineralization process. Understanding how the process operates in a biological environment is a valuable guide to the synthesis of novel advanced material and developing important industrial processes. Like the mechanism of organisms, mollusks were also synthesized from interaction between organic matrices and minerals and their morphology was designed through biomineralization. In this study, shell formation has been studied as a bio-model and the application of biomimetics based on biomineralization is focused.

• Wind and Structures
• /
• v.3 no.3
• /
• pp.143-158
• /
• 2000

This report presents the findings of a one-year monitoring effort to empirically characterize and evaluate the nature of near-ground winds for structural engineering purposes. The current wind engineering practice in the United States does not explicitly consider certain important near-ground wind characteristics in typical rough terrain conditions and the possible effect on efficient design of low-rise structures, such as homes and other light-frame buildings that comprise most of the building population. Therefore, near ground wind data was collected for the purpose of comparing actual near-ground wind characteristics to the current U.S. wind engineering practice. The study provides data depicting variability of wind speeds, wind velocity profiles for a major thunderstorm event and a northeaster, and the influence of thunderstorms on annual extreme wind speeds at various heights above ground in a typical rough environment. Data showing the decrease in the power law exponent with increasing wind speed is also presented. It is demonstrated that near-ground wind speeds (i.e., less than 10 m above ground) are likely to be over-estimated in the current design practice by as much as 20 percent which may result in wind load over-estimate of about 50% for low-rise buildings in typical rough terrain. The importance of thunderstorm wind profiles on determination of design wind speeds and building loads (particularly for buildings substantially taller than 10 m) is also discussed. Recommendations are given for possible improvements to the current design practice in the United States with respect to low-rise buildings in rough terrain and for the need to study the impact of thunderstorm gust profile shapes on extreme value wind speed estimates and building loads.

• Journal of the Korean Society of Hazard Mitigation
• /
• v.10 no.3
• /
• pp.53-59
• /
• 2010

Globally, the actual circumstance is that local downpours are occurring and the droughts are extensively continuing on and the occurrence of large-scale earthquakes is increasing as a result of changes in nature environment. It is being pointed out also in the case of Korea for the urgent countermeasures against the situation of repeated occurrence of disasters in the regions where the concept of disaster prevention has not been applied. Accordingly, the National Emergency Management Agency has been implementing the formation of disaster prevention trial towns since 2009 for the regions vulnerable to disasters and searching for plans to improve disaster prevention measures. Therefore, the concept of disaster prevention town and the program type were summarized in this study, and the development strategy for developing disaster prevention town was presented through the related laws and policies and the case analysis of domestic and international trial programs, and the basic concept of forming disaster prevention town was presented to present basic information for developing disaster prevention town.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.15 no.6
• /
• pp.3616-3624
• /
• 2014

The aim of this study was to inquire into the perceptions and the needs of parents on their forest experience activity. To achieve this, a survey was carried out on 250 parents of children in a Gyeonggi-based private kindergarten from December 26 to December 31, 2013. The results are as follows. For the perceptions of parents on the forest experience activity, the 'perception on overall effectiveness' was the highest, followed in order by 'perception on educational effectiveness' and 'general perception'. For the needs of parents on their forest experience activity, 58.2% of them recognized the importance of regular forest experience activity. For the necessity of an annual program, 60.7% of them recognized the necessity of a planned annual program. For the recommendation of forest experience activity, 61.1% of them gave a strong recommendation for forest experience activity. As stated above, most parents positively viewed children's forest experience activity in the environment as it is difficult to approach nature in downtown areas, and children also highly viewed the educational effectiveness of it.

• Journal of Korea Multimedia Society
• /
• v.13 no.2
• /
• pp.298-307
• /
• 2010

The grass is one of important components that cover the wide surfaces in the application such as game or real time simulation. Actually, it not easy to render effectively numerous grasses that grow over the wide terrain. To solve the difficulty, we must find a solution to the two contradictions in terms : quality and calculation cost. As a solution to the above-mentioned task, in this paper, we propose an efficient method to represent the natural grasses by introducing fractal theory and instancing technique. Although the existing grass representation methods make use of a simple rule of applying a basic grass model repeatedly in rendering process, on the contrary we take advantage of the basic property of fractal's self-similarity and we devise a natural representation method suited to the given environment by introducing two important growth factors such as nature of terrain and quantity of light, and finally we apply a GPU-based shader instancing technique to rendering numerous grass models in real-time.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.17 no.7
• /
• pp.451-458
• /
• 2016

The Crying of Lot 49 presents the writer's major ideas through Oedipa Maas who tries to seek out the truth of a mysterious underground postal network, Tristero. Of the many themes inherent in The Crying of Lot 49, probably the most important and widespread of all is 'paranoia', which plays a major role in helping us to comprehend and appreciate other thematic ideas. The other main motif in this novel is a conspiracy. However, it is really difficult to distinguish between reality and fantasy in the crazed environment. Therefore, it is uncertain that the existence of Tristero is a real conspiracy or just a paranoia. The world revealed to her after considering Tristero's knowledge is totally different from the world previously familiar to Oedipa and she discovers that the nature and origins of Tristero will not be a quest of simple curiosity any longer and she greatly needs to escape from the closed system of perception. The secret of the Tristero case should be found in order to return to reality. In addition, accepting what Oedipa has seen and heard may be a reasonable way for her to become a paranoiac.

• Current Research on Agriculture and Life Sciences
• /
• v.25
• /
• pp.19-23
• /
• 2007

This research to streets at Daegu, and view adjective how people react when draw a bird into interior in city utilize and examine becoming direction of street trees system. Findings on survey, citizens appear by average 2.87 in management degree of street trees and average 2.76 in various of species of trees, discontent thing more or less by average 2.91 in satisfaction of the beauty, and demonstrate high shame from satisfaction for season stuff to comparative high 3.24, generally, citizens appear by there are parts to improve by do dissatisfaction about street trees system at Daegu. Also, street trees 2 lines plantings for a bird is average 3.05, shows affirmative feedback about that shrub utilization for a bird see high numerical value by average 3.4 and people draw a bird to space of city. Therefore, construct street trees friendly to the nature and be considered to need to re-establish set street trees environment in citizens preference to recover city ecosystem. As result that examine reaction which treat in street trees planting programs to draw birds into city through view adjective, Likert scales about 2 lines plantings of street trees and additional planting of shrub show affirmative feedback by average 3.4 both ordinary people and specialist group, if people want to draw birds into city by various of method, various research should be accomplished.

• Journal of the Korean Institute of Landscape Architecture
• /
• v.30 no.2
• /
• pp.63-69
• /
• 2002

The Second Namsan Tunnel required renovation. The landscape design was conducted as part of the comprehensive programs for renovation. The landscape design covered site analysis, design development, a working drawing and a maintenance plan. In May of 2001, the Second Namsan Tunnel was renovated and reopened to traffic. The tunnel was recreated as a new type of tunnel with function and beauty. The entrance and retaining wall of the tunnel has public character. Users are greatly affected by the entrance and retaining walls along roads. The landscape architect had to find new materials and methods to improve the environment and to combine artwork with the entrance and walls of the tunnel. The surface of the tunnel entrance and retaining walls are artistically treated with ceramic tiles and paint. Various regional characteristics and cultural meaning are symbolically expressed. Or the tunnel entrance from the Joong-gu side, entitled "Glory of the Future", the hibiscus symbolizes the bright and glorious future of Korea. On the retaining walls, entitled "Hope", the promising Joong-gu is symbolized through image of Korean magpies, mountains, rocks, roses, winds and nature. As for the tunnel entrance from the Yongsan-gu side, entitled "Vivid Spirit", pine trees symbolize the Koreans′strong will and an enterprising spirit. On the retaining walls, entitled "Lively Motions", Yongsan-gu is symbolized through image of pigeons, mountains, rocks, roses, winds and clear skys. The entrance and retaining wall of the Second Namsan Tunnel, whose surfaces are treated with tiles and paint with artistic value, would create an atmosphere using large-scale wall paintings. In this artwork, users would perceive a unique sense of place through the symbolic images of the vertical planes of the tunnel.