• Transactions of the Korean Society of Automotive Engineers
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• v.21 no.4
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• pp.62-69
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• 2013

Visual demands associated with in-vehicle display usage and text messaging distract a driver's visual attention from the roadway. To minimize eyes-off-the-road demands, voice interaction systems are widely introduced. Under cognitively distracted condition, however, awareness of the operating environment will be degraded although the driver remains oriented to the roadway. It is also know that the risk of inattentive driving varies with age, thus systematic analysis of driving risks is required for the older drivers. This paper aims to understand the age-related driving performance degradation and visual attention changes under auditory cognitive demand which consists of three graded levels of cognitive complexity. In this study, two groups, aged 25-35 and 60-69, engaged in a delayed auditory recall task, so called N-back task, while driving a simulated highway. Comparisons of younger and older drivers' driving performance including mean speed, speed variability and standard deviation of lane position, and gaze dispersion changes, which consist of x-axis and y-axis of visual attention, were conducted. As a result, it was observed that gaze dispersion decreased with each level of demand, demonstrating that these indices can correctly rank order cognitive workload. Moreover, gaze dispersion change patterns were quite consistent in younger and older age groups. Effects were also observed on driving performance measures, but they were subtle, nonlinear, and did not effectively differentiate the levels of cognitive workload.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.24 no.3
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• pp.299-309
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• 2006

In recent years, a large natural disasters have occurred due to worldwide abnormal weather and the amount of damage has been increased more resulting from high density population and a large-sized buildings of the urbanized area. In this study. we estimate the flooded area according to rainfall probability intensify and sea level in Woreong dong, Masan occurred flood damages by typhoon Maemi using SWMM, a dynamic rainfall-runoff simulation model in urban area, and then analyze the damage of flood expected area through connecting with GIS database. In result, we can predict accurately expected area of inundation according to the rainfall intensity and sea level rise through dividing the study area into sub-area and estimating a flooded area and height using SWMM. We provide also the shelter information available for urban planning and flood risk estimation by landuse in expected flood area. Further research for hazard management system construction linked with web or wireless communication technology expects to increase its application.

• Journal of Environmental Science International
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• v.22 no.1
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• pp.47-57
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• 2013

Studies evaluating the health effects of hazardous air pollutants assume that people's exposure to typical pollutant level is the same as specific regional pollutant level. However, depending on social and demographic factors, time-activity pattern of people can vary widely. Since most people live in indoor environments over 88% of the day, evaluating exposure to hazardous air pollutants is hard to characterize. Objective of this study was to estimate the exposure levels of university students of $NO_2$, VOCs(BTEX) and $PM_{10}$ using the scenarios with time-activity pattern and indoor concentrations. Using data from time-use survey of National Statistical Office in 2009, we investigated time-activity pattern of university students and hourly major action. A total of 1,057 university students on weekday and 640 on weekend spent their times at indoor house 13.04 hr(54.32%), other indoors 7.70 hr(32.06%), and transportation 2.36 hr(9.83%). Indoor environments in which university students spent their times were mainly house and school. Air pollutants concentrations of other indoor environments except house and school such as bar, internet cafe and billiard hall were higher than outdoors, indicating that indoor to outdoor ratios were above 1. According to three types of exposure scenarios, exposure to air pollutants could be reduced by going home after school.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 1998.10b
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• pp.11-25
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• 1998

Many Countries have made efforts to assist ships navigate accurately , safely and expeditiously for the safety control against increasing marine traffic , in their coastal waters. However, they are exposed in spite of these efforts,to risks of casulaties and marine polluation caused by traffic congestion when ships are navigating through waterways approaches to ports or harbors and in narrow fairways. Therefore, efficient control of VTS in Port is necessary nowadays to provide ships with necessary service , which interacts with shipping and organize the flow of traffic so as to maximize the efficiency of the port or harbor while minimizing the risk of accident and environmental pollution. Even though the navigation condition of ships is very inferior compared to other ports in Korea, such as the big difference between the ebb and flood tide, the frequent fog, the narrow fairway , the density of navigation traffic in Inchon Port is high and transportation quantity of dangerous cargoe increases gradually. In cosideration of the characteristics of natural circumstance and traffic circumstance the VTS established newly in Inchon port have to operate efficiently. The purpose of this study is to help efficient operation of VTS in Inchon port by accomplishing both the literature research and questionnaire survey. Questionnaire survey was read to the VTS personnel in Inchon Port and customer familiar to Inchon Port such as ship navigators, pilots, shipping companies and so on. Most of ship navigators who occupy half of the respondents are Korean Officer who had responded while they were calling at Inchon port. The conclusions and recommendations includes ; First, the service area should be extended over Designated area to provide the vessel with navigational assistance service regarding the information of traffic congestion area, fishing boat and small ship's activities. Second, the types of information service to be offered are ship's movement and weather condition inthe vicinity of the port and state of fairway in the approaching channel to thte fairway. Third, VTS personnel should be upgraded by the on-the-job training and continuous simulation training as well as supplement of the qualified personnel for VTS operation. Fourth , the Harbor Master System to be introduced for safe navigation and efficient port operation.

• Tunnel and Underground Space
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• v.12 no.1
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• pp.19-30
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• 2002

Rock joint orientation is one of important geometric attributes that have an influence on the stability of rock structures such as rock slopes and tunnels. Especially, statistical models of the geometric attributes of rock joints can provide a probabilistic approach of rock engineering problems. The result from probabilistic modeling relies on the choice of statistical model. Therefore, it is critical to define a representative statistical model for joint orientation data as well as joint size and intensity and build up a series of modeling procedure including analytical validation. In this paper, we have examined a theoretical methodology for the statistical estimate and hypothesis analysis based upon Fisher distribution and bivariate normal distribution. In addition, we have proposed the algorithms of random number generator which is applied to the simulation of rock joint networks and risk analysis.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.41 no.6
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• pp.488-494
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• 2013

The control law design and analysis environment of the FBW helicopter system have been developed using model base design method. The model based design is generally used in a aircraft, unmanned aerial system and automobile as well as rotorcraft development. The model based design provides many advantages such as development risk and schedule reduction using simulation and autocode generation. This paper describes a development of process for verification and validation of auto generated code for FBW helicopter flight control law. And this process is applied for Fly-By-Wire Helicopter Development Project. The results of functional test for auto generated code meet several specific requirements.

• Journal of the Korean Society of Safety
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• v.35 no.2
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• pp.100-110
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• 2020

Recently, the frequency of typhoon and torrential rain due to climate change is increasing. In addition, the upsurge in the complexity of urban sewer network and impervious surfaces area aggravates the inland flooding damage. In response to these worsening situations, the central and local governments are conducting R&D tasks related to predict and mitigate the flood risk. Researches on the analysis of inundation in urban areas have been implemented through various ways, and the common features were to evaluate the accuracy and justification of the model by comparing the model results with the actual inundation data. However, the evaluation procesure using available urban flooding data are not consistent, and if there are no quantitative urban inundation data, verification has to be performed by using press releases, public complaints, or photos of inundation occurring through 'CCTV'. Because theses materials are not quantitative, there is a problem of low reliability. Therefore, this study intends to develop a comparative analysis procedure on the quantitative degree and applicability of the verifiable inundation data, and a systematic framework for the performance assessment of urban flood analysis model was proposed. This would contribute to the standardization of the evaluation and verification procedure for urban flooding modelling.

• Journal of Korea Multimedia Society
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• v.4 no.4
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• pp.333-338
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• 2001

In this paper, fuzzy-ARTMAP equalizer is developed mainly for overcoming the obstacles, such as complexity and long training, in implementing the previously developed neural-basis equalizers. The proposed fuzzy-ARTMAP equalizer is fast and easy to train and includes capabilities not found in other neural network approaches a small number of parameters, no requirements for the choice of initial weights, no risk of getting trapped in local minima, and capability of adding new data without retraining previously trained data. In simulation studies, binary signals were generated at random from linear channel with Gaussian noise. The performance of the proposed equalizer is compared with other neural net basis equalizers, such as MLP and RBF equalizers. The fuzzy ARTMAP equalizer combines relatively simple structure and fast processing speed; it gives accurate results for nonlinear problems that cannot be solved with a linear equalizer.

• Journal of Korea Multimedia Society
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• v.11 no.5
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• pp.661-672
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• 2008

Mobile Ad-hoc NETwork is a kind of self-controlled network composed only of mobile hosts. Since its range of use is gradually expanding into various sections applicable to practical lives, active researches are being conducted on it. However, as it depends on cooperation of nodes composing the entire network, due to weakness of wireless link and lack of its central infrastructure, so it is exposed to more serious risk than general network in security. Therefore, this paper proposes Cluster-Based Dynamic Authentication that enables only reliable nodes to participate in communication, by solving lack of centralized infrastructure, using hierarchical Mobile Ad hoc NETwork structure based on cluster, and by complementing security weakness through mutual authentication between hierarchical nodes. Simulation shows that the proposed scheme can complement security weakness of Mobile Ad hoc NETwork and that it is more adequate in reliability and expandability than the existing schemes.

• Journal of the Korean Society of Safety
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• v.31 no.2
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• pp.70-75
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• 2016

Recently, coastal erosion has been widely in progress and the erosion level becomes also serious in the world wide, espeically in East Sea in Korea. Since it would threaten the life, economics and security risk, it is necessary to much comprehend the reason why coastal erosion has occurred according to the geographical characteristics. Meanwhile, analysis about hydrodynamics of the solitary wave such as tunami in swash zone is needed for the best management practice of coastal erosion. Solitary wave is nonlinear wave and can be reproduced in the laboratoy scale by openning suddenly a sluice gate with water head difference, of which methodology was found in the literature, since it could be simply determined by a significant wave height. Thus, in this sutdy the generation of solitary wave was experimentalized using the sluice gate. Experimental conditions were classified by angles of a beach slope, a water level in a beach slope and a difference of water level between in a headtank and a channel bed. Two kinds of dimensionless analyses based from experimental results in this study were presented; the first analysis indicates nondimensionalization between the wave height and the water level in a beach slope in order to investigate characteristics of solitary wave approaching the beach. The second shows the other nondimensionalization between dynamic pressure and static pressure on a beach slope to investigate the relationship between wave breaking and wave pressure. Under the same conditions as laboratory experiments, the numerical results computed with a SWAN model embedded in FLOW 3D were compared in terms of wave height, and pressure on the beach slope, which shows good agreement with each other. Overall results from this study could provide fundamental hydraulic data for the reliabile verification of numerical simulation results about coastal erosion in swash zone caused by solitary waves.