• Water for future
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• v.27 no.4
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• pp.145-154
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• 1994

A dynamic model for the pollutant transport analysis in a river is developed by preissmann scheme and lagrangian method considering tidal effects. A generalized Lagranian model alleviate the numerical difficulties associated with the use of the Eulerian reference frame. Comparing the finite difference and finite element solutions of one-dimensional transport equation, Lagrangian model shows the most stable and accurate results. The flow model is calibrated using the recorded flood data in the downstream of the Han River. The particle paths-of-travel is computed by the model for the various low flow conditions. The model will provide operational informations useful for water quality management in the downstream of the Han River.

• Journal of Information Technology Services
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• v.7 no.4
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• pp.231-246
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• 2008

This paper suggests an e-learning system model, a goal-driven personalized e-learning system, which increase the effectiveness of learning. An e-learning system following this model makes the learner choose the learning goal. The learner's choice would lead learning. Therefore, the system enables a personalized adaptive learning, which will raise the effectiveness of learning. Moreover, this paper proposes a SCORM standard, which modifies SCORM 2004 that has been insufficient to implement the "goal driven personalized e-learning system." We add a data model representing the goal that motivates learning, and propose a standard for statistics on learning objects usage. We propose each standard for contents model and sequencing information model which are parts of "goal driven personalized e-learning system." We also propose that manifest file should be added for the standard for contents model, and the file which represents the information of hierarchical structure and general learning paths should be added for the standard for sequencing information model. As a result, the system could sequence and search learning objects. We proposed an e-learning system and modified SCORM standards by considering the many factors of adaptive learning. We expect that the system enables us to optimally design personalized e-learning system.

• Journal of Soil and Groundwater Environment
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• v.12 no.5
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• pp.33-36
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• 2007

In recent years the convective-dispersive equation has been often discredited in predicting subsurface solute transport under field conditions due to presence of preferential flow paths. Kim et al. (2005) proposed a simple equation that can predict the breakthrough of solutes without excessive data requirements. In their Generalized Preferential Flow Model (GPFM), the soil is conceptually divided in a saturated "distribution layer" near the surface and a "conveyance zone" with preferential flow paths below. In this study, we test the model with previously published data, and compare it with a classical convective-dispersive model (CDM). With three parameters required-apparent water content of the distribution zone, and solute velocity and dispersion in the conveyance zone-GPFM was able to describe the breakthrough of solutes both through silty and sandy loam soils. Although both GPFM and CDM fitted the data well in visual, variables for GPFM were more realistic. The most sensitive parameter was the apparent water content, indicating that it is the determining factor to apply GPFM to various soil types, while Kim et al. (2005) reported that changing the velocity of GPFM reproduced solute transport when same soils were used. Overall, it seems that the GPFM has a great potential to predict solute leaching under field conditions with a wide range of generality.

• Journal of dental hygiene science
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• v.11 no.6
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• pp.563-571
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• 2011

The purpose of this study was to identify the major variables against oral health promotion behaviors for collegian in Ulsan area. The measured variables for the oral promotion behaviors presently are previous oral health experience, stress by study, subjective oral health, perceived benefit, perceived barrier, self-esteem, self-efficacy, social support, oral health LOC(locus of control), life satisfaction, emotion and intension based on the Pender's 3th health model as a theoretical model in general health promotion behavior. Total data 330 were analyzed by SPSS 18.0 and AMOS 18.0 program and path analysis method was used to verify the model's fitness. Results for this study were as follows: Firstly, the fitness degrees of research model was ${\chi}^2=39.06$(P>.05), GFI = .982, AGFI = .948, NFI = .967, NNFI = .982, RMSR = .028, so it was apparent that this model was well fitted. Secondly, 27 out of 39 total paths were turned out correspond with the hypothetical model which accepted as direct effect. And two paths had statistical significance in direct. Thirdly, the most positive influences on the oral health promotion behaviors presently were previous oral health experience, subjective oral health, social support, self-efficacy, intension, oral health LOC. And the most negative influences was perceived barrier. So, results from this model we could contribute to identify theirs oral health behavior patterns for collegian in Ulsan.

• Transactions of the Korean hydrogen and new energy society
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• v.22 no.3
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• pp.305-312
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• 2011

The use of a separator to control stack temperature in a molten carbonate fuel cell was studied by numerical simulation using a computational fluid dynamics code. The stack model assumed steady-state and constant-load operation of a co-flow stack with an external reformer at atmospheric pressure. Representing a conventional cell type, separators with two flow paths, one each for the anode and cathode gas, were simulated under conditions in which the cathode gas was composed of either air and carbon dioxide (case I) or oxygen and carbon dioxide (case II). The results showed that the average cell potential in case II was higher than that in case I due to the higher partial pressures of oxygen and carbon dioxide in the cathode gas. This result indicates that the amount of heat released during the electrochemical reactions was less for case II than for case I under the same load. However, simulated results showed that the maximum stack temperature in case I was lower than that in case II due to a reduction in the total flow rate of the cathode gas. To control the stack temperature and retain a high cell potential, we proposed the use of a separator with three flow paths (case III); two flow paths for the electrodes and a path in the center of the separator for the flow of nitrogen for cooling. The simulated results for case III showed that the average cell potential was similar to that in case II, indicating that the amount of heat released in the stack was similar to that in case II, and that the maximum stack temperature was the lowest of the three cases due to the nitrogen gas flow in the center of the separator. In summary, the simulated results showed that the use of a separator with three flow paths enabled temperature control in a co-flow stack with an external reformer at atmospheric pressure.

• Convergence Security Journal
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• v.11 no.1
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• pp.71-77
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• 2011

NCW(Network Centric- Warfare) encompasses the concept to use computer data processing and network linkage communications techniques, share information and furthermore, enhance the effectiveness of computer-operating systems. As IT(Information & Technology) have become developed in the recent years, the existing warfare system-centered conventional protocol is not use any longer. Instead, network-based NCW is being widely-available, today. Under this changing computer environment, it becomes important to establish algorithm and build the stable communication systems. Tools to identify malign node factors through Wireless Ad-hoc network cause a tremendous error to analyze and use paths of even benign node factors misreported to prove false without testing or indentifying such factors to an adequate level. These things can become an obstacle in the process of creating the optimum network distribution environment. In this regard, this thesis is designed to test and identify paths of benign node factors and then, present techniques to transmit data through the most significant open short path, with the tool of MP-SAR Protocol, security path search provider, in Ad-hoc NCW environment. Such techniques functions to identify and test unnecessary paths of node factors, and thus, such technique users can give an easy access to benign paths of node factors.

• Journal of Venture Innovation
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• v.1 no.1
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• pp.29-47
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• 2018

As the radical advances of digitalization, our daily life have been fundamentally changed. As a result, the customer journey also changed as compared with previous periods. This study analyzed customer journy of digital age. First, historical trends and issues of customer journey research were analyzed. Second, Comparative analysis of customer journey of digital and previous age were conducted. No more funnel model of customer journey which assumed hierarchical and linear paths was valid. Customer journey of digital age will be non-linear and circular paths.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.9
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• pp.4287-4306
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• 2016

Network resilience provides an effective way to overcome the problem of network failure and is crucial to Internet protocol (IP) network management. As one of the main challenges in network resilience, recovering from link failure is important to maintain the constancy of packets being transmitted. However, existing failure recovery approaches do not handle the traffic engineering problem (e.g., tuning the routing-protocol parameters to optimize the rerouting traffic flow), which may cause serious congestions. Moreover, as the lack of QoS (quality of service) restrictions may lead to invalid rerouting traffic, the QoS requirements (e.g., bandwidth and delay) should also be taken into account when recovering the failed links. In this paper, we first develop a probabilistically correlated failure model that can accurately reflect the correlation between link failures, with which we can choose reliable backup paths (BPs). Then we construct a mathematical model for the failure recovery problem, which takes maximum rerouting traffic as the optimizing objective and the QoS requirements as the constraints. Moreover, we propose a heuristic algorithm for link failure recovery, which adopts the improved k shortest path algorithm to splice the single BP and supplies more protection resources for the links with higher priority. We also prove the correctness of the proposed algorithm. Moreover, the time and space complexity are also analyzed. Simulation results under NS2 show that the proposed algorithm improves the link failure recovery rate and increases the QoS satisfaction rate significantly.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.41 no.2
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• pp.103-109
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• 2017

Metal 3D printing, which is an additive metal manufacturing (AMM) process, enables the development of full-density metallic tools and parts using metal powders that are precisely delivered and controlled for deposition with no powder bed. However, some unknown geometric defects and irregular geometric features on an STL model can possibly result in incorrect metal part fabrication after the build. This study first proposes a methodical approach for verifying the build part, including the missing facet problems in an STL model, by defining some irregular features that possibly exist on the part. Second, 2D tool paths on each build layer were investigated for detecting any singular region inside the layer. The method was implemented for building two sample STL models using a direct energy deposition process, and finally, it was visually simulated for diagnosis.

• Spatial Information Research
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• v.18 no.4
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• pp.89-98
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• 2010

Recently, the target of navigation system is moving from the cars to pedestrians. Many researches are in progress regarding pedestrian navigation, However, in most cases, the path-finding is based on the existing node/link network model. which is widely used for the car navigation, and thus showing its limitation. The reasons arc that a) unlike with a car, the paths that pedestrians take arc not limited to the roads, b) pedestrians an~ not restricted in rotation or direction, and c) they can freely move within the walkable space. No alternatives have been offered yet, especially for openspaces such as a park or square. Therefore, in this research, we suggested appropriate methods to create paths that can be used in pedestrian navigation service, by using motion-planning technology, which is used in the field of robotics for planning the motion of an object, and conducted tests for their applicability.