• Journal of the Korean Society of Industry Convergence
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• v.26 no.1
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• pp.163-173
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• 2023

In this study, topographic change analysis was performed on the Nak-dong River estuary area. The factors affecting the changes in the bathymetry of the Nak-dong River estuary were analyzed using data from the discharge, suspended sediments, and rainfall of the Nak-dong River barrier as analysis data. As a result, erosion and sedimentation are judged to appear repeatedly due to complex effects such as discharge of the estuary barrier of the Nak-dong River and invasion of the open sea waves, and it is judged that there is no one-sided tendency. However, as a result of checking the data in the second half of 2020, it was possible to confirm a large amount of erosion, which is different from the past data. It is clear that this is a result beyond the trend of erosion in the first half and sedimentation in the second half. In the summer of 2020, the rainy season lasted for more than a month and torrential rains occurred, which seems to be due to about three times higher rainfall than other periods, and erosion is believed to have occurred as the discharge increased rapidly compared to the time deposited by river water outflow. In addition, compared to other times, the influence of many typhoons in the summer of 2020 is believed to have affected the topographical change at the mouth of the Nak-dong River.

• Journal of Korea Planning Association
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• v.54 no.6
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• pp.68-79
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• 2019

The purpose of this study is to propose a transit accessibility analysis method based on temporal variability of travel time. In this study, transit accessibility was defined in three levels (in transit route, spot and region unit) to present findings from different spatial scopes. Recently, Jeju special self-governing province reorganized bus system of the island. To compare transit accessibility before and after transit policy implementation, the reorganized bus system of Jeju special self-governing province was selected as a case study. This study used General Transit Feed Specification (GTFS) data format as storage public transit information, and calculated travel time using ArcGIS GTFS networks analysis tools. In the analysis of individual transit route level, we found the 3 types of accessibility changes which is increments, no significant changes and reductions and these results come from transit route change (number of transfer, distance change) rather than changes of vehicle interval. We found increases of inflow and outflow speed in most target spots and overall transit accessibility has been substantially improved in Jeju island. This study implies that accounting for temporal variability of travel time in accessibility analysis can result in more useful and sophisticated accessibility information in decision-making processes.

• Tunnel and Underground Space
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• v.29 no.1
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• pp.52-63
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• 2019

It is highly in demand to establish a bunker-type underground data center to ensure the safety of national critical data, such as financial information and medical information, and prevent those outflow of national important data. In particular, the security of a data center which is a key national structure has become a social issue due to EMP weapon and earthquakes, but data centers in the nation have not been able to deal with it properly. Therefore, it is necessary to develop an underground data center that is safe from human-induced and natural disasters while reducing power costs by utilizing the benefits of underground spaces such as constant temperature and isolation. In this analysis, the status and trends of data centers around the world were analyzed and based on those trend analyses, the research strategy for underground data center were discussed.

• Journal of the Society of Disaster Information
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• v.18 no.1
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• pp.1-9
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• 2022

Purpose: In this study, we used hydrophilic waterstop used in geosynthetics vertical barrier system to evaluate the performance of impermeability under sealing conditions. Method: ASTM D5887 and ASTM D6766 were applied to determine the capability of the connection during the geosynthetics vertical barrier system. Hydrophilic waterstop was saturated in each solution and the weight, thickness, and volume changes were analyzed over elapsed time. Hydrophilic waterstop was installed at the geosynthetics vertical barrier system connection to evaluate the permeability characteristics. Results: As the expansion reaction time of hydrophilic waterstop increased relatively under saline conditions, the decrease in permeability also showed a smaller decrease in fresh water. Furthermore, the method of engagement of the geosynthetics vertical barrier system showed somewhat better performance of the impermeability due to the large pressure resistance caused by the roll joint type than interlock type. Conclusion: In urban pollutants, which can estimate the outflow of pollutants such as oil storage facilities and industrial complexes, proactive response technologies that can prevent the contaminant diffusion can significantly reduce the damage.

• The Journal of the Korea institute of electronic communication sciences
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• v.8 no.12
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• pp.1841-1848
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• 2013

In this paper, the plans for improvement of real-time security monitoring accuracy and expansion of control region were investigated through comprehensive and systematic collection and analysis of the anomalous activities that inflow and outflow in the network on a large scale in order to overcome the existing security monitoring system based on stylized detection patterns which could correspond to only very limited cyber attacks. This study established an anomaly observation system to collect, store and analyze a diverse infringement threat information flowing into the darknet network, and presented the information classification system of cyber threats, unknown anomalies and high-risk anomalous activities through the statistics based trend analysis of hacking. If this security monitoring system utilizing darknet traffic as presented in the study is applied, it was indicated that detection of all infringement threats was increased by 12.6 percent compared with conventional case and 120 kinds of new type and varietal attacks that could not be detected in the past were detected.

• Spatial Information Research
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• v.10 no.2
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• pp.301-316
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• 2002

Soil Loss by outflow of water or rainfall has caused many environmental problems as declining agricultural productivity, damaging pasture and preventing flow of water. Also, validity pondage of reservoir or dam is decreased by rivers inflow of eroded soil. Revised Universal Soil Loss Equation(RUSLE) is mainly used to presume soil loss amount of basin using GIS. But, because comparison with survey data is difficult, it is no large meaning that estimate calculated soil loss amount as quantitative. This research used unit sediment deposit survey data of Bo-seong basin for quantitative conclusion of soil loss amount that calculate on RUSLE. Through comparison examination with unit sediment yield that calculate on RUSLE and unit sediment deposit survey data, we can estimate resolution far RUSLE Model. As a result, cell size of 150m was estimated by thing which is most suitable.

• The KIPS Transactions:PartC
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• v.8C no.6
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• pp.731-740
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• 2001

Multi-distributed web cluster model expanding conventional cluster system is the cluster system which processes large-scaled work demanded from users with parallel computing method by building a number of system nodes on open network into a single imaginary network. Multi-distributed web cluster model on the structured characteristics exposes internal system nodes by an illegal third party and has a potential that normal job performance is impossible by the intentional prevention and attack in cooperative work among system nodes. This paper presents the mutual authentication protocol of system nodes through key division method for the authentication of system nodes concerned in the registration, requirement and cooperation of service code block of system nodes and collecting the results and then designs SNKDC which controls and divides symmetrical keys of the whole system nodes safely and effectively. SNKDC divides symmetrical keys required for performing the work of system nodes and the system nodes transmit encoded packet based on the key provided. Encryption packet given and taken between system nodes is decoded by a third party or can prevent the outflow of information through false message.

• Journal of the Korean Association of Geographic Information Studies
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• v.23 no.2
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• pp.36-52
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• 2020

This study performed 2-D(two-dimensional) hydrodynamic analysis using EFDC in the Nakdong River. For the simulation of the flood season and non-flood season, the measured data including water level, weir outflow and tributary inflow were used, and the accuracy and applicability of the model were verified by comparing the measured water level and computed one. In addition, statistical quantitative assessment of the model performance was performed by estimating PBIAS, RSR, and RMSE for the computed water level. Then, the average velocity for each section between weirs was calculated by applying constant discharge conditions, and it was compared and verified with the measured velocity by Hydrological Survey Center. In this study, a simple method for estimating the arrival time was proposed, and it is expected that it will be practically applicable in field practices such as flood forecasting and warning.

• Journal of Digital Convergence
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• v.9 no.4
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• pp.281-289
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• 2011

This paper provides the emerging flow of new communication technology using ubiquitous learning (u-Learning). In the intelligent Ubiquitous environment, humans and devices with computing abilities become interoperable. u-Learning will lead students to open their minds to the world and motivate self-learning, which may lead them to learn and communicate more efficiently, and save time, cost and energy. Through case research, regarding education, learning attitude, custom and, personal relations, one must solve the fundamental issues of misuse and outflow problems regarding personal information that will be widely collected in detail than the present condition, and in order for this not to happen, further support of the law and system, plus ethical perspectives must be considered in order to progress.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.21 no.1
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• pp.125-133
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• 2011

According to proliferation of mobile devices, security threats have been continuously increased such as illegal or unintentional file transmission of important data to an external mass-storage device. Therefore, we propose a protection method to prohibit an illegal outflow to this device and implement this method. This method extracts signatures from random locations of important file and uses them to detect and block illegal file transmission. To get signatures, a target file is divided by extracting window size and more than one signatures are extracted in this area. To effective signature sampling, various extraction ways such as full, binomial distribution-based and dynamic sampling are implemented and evaluated. The proposed method has some advantages. The one is that an attacker cannot easily predict the signature and its extraction location. The other is that it doesn't need to modify original data to protect it. With the help of these advantages, we can say that this method can increase efficiency of easy-to-use and it is a proper way leakage prevention in a mobile device.