• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.8
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• pp.3345-3351
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• 2012

In this study, simulation of an underwater platform system which is able to perform the underwater test is implemented to predict its dynamic characteristics. Accordingly, its governing equations are derived to construct the mathematical model. From the proposed model, the time in flooding and the pressure of ballast tank in blowing air to come up are predicted. In addition, simulation of the stability of the system for repulsive force of the tube by compressed air is carried out. Their results will be used to select valves, air tanks as well as design the system including ballast tanks. And they will help users operate it efficiently.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.18 no.4
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• pp.348-359
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• 2006

The city of Mokpo suffers lowland inundation damages by sea water flooding even without harsh weather like a typhoon, due to the low level urban infrastructure facilities, oceanic environmental changes by constructions of seadike/seawall and sea level rise caused by global warming. This study performs constructing the simulation system which employs the MIKE21 software. And the system is applied to several typhoon- induced surges which had resulted in inundation at Mokpo. Virtual situation of flooding is simulated in case 59 cm of surge height, which had been occurred actually by RUSA(0215), coincides with Approx. H.H.W. Then the water level of 545 cm corresponds to the extreme high water level(544 cm) for 10 year return period after the construction of Geumho seawall. The results show rapid and broad inundation at Inner-Port, requiring additional preparations for flood protections.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.6A
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• pp.617-625
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• 2011

In wireless sensor networks, data dissemination protocols have been proposed for mobile sink groups that are characterized by geographically staying closely and collective movement. They usually exploit flooding technology for mobility supporting and data delivery guarantee. However, it causes the excessive energy consumption of all sensor nodes in the group region due to data delivery participation. Moreover, the costs of the flooding would become higher in proportional to the group region. In this paper, we propose an energy efficient data dissemination scheme that resolves these problems. The virtual infrastructure called a 'pipe' is used as a rendezvous area. A source delivers data to the pipe, from which member sinks in the group retrieve it directly. Simulation results showed that this solution has better performance than existing protocols in terms of energy consumption as it reduces the number of regional flooding and eliminates unnecessary data flooding.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.42 no.6 s.336
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• pp.23-32
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• 2005

This paper proposes a new algorithm for the energy constraint ad-hoc network which efficiently spread the energy usage over the network through the backup route scheme in order to increase the network lifetime. Recently, the various energy-efficient routing algorithms based on On-demanding method are proposed. Among them, PSR(Power-aware Source Routing) increased the network lifetime through the periodical route alternation depended on the use of the battery while DSR(Dynamice Source Routing) uses only the route selected during the route discovery phase. But PSR has a problem that it increases the route overhead because of the frequent flooding for the route alternation. For solving this problem, we propose HPSR(Hierarchical Power-aware Source Routing) which uses the backup route set during the route discovery in order to alternation the route without the flooding. HPSR increases the network lifetime due to the frequent route alternation using backup route while it decreases the routing overhead due to the reduced flooding. In this paper, we also prove the performance of HPSR through the simulation using OPNET.

• Journal of Korea Multimedia Society
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• v.16 no.3
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• pp.330-335
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• 2013

It is expected that the vehicle safety systems using vehicle-to-vehicle communication can reduce the possibility of vehicle collision and prevent the chain crash by promptly delivering the status of neighboring vehicles. Many IEEE 802.11 DCF based Flooding schemes have been proposed, but they may generally expose the problems that the chances of a chain-collision reaction are sharply increased as the vehicle density has increased. Therefore, this paper proposes the chain-collision prevention scheme using a broadcasting-based adaptive report. The proposed method can adaptively allocate the preoccupancy right based on a quantitative priority order and then promptly deliver the warning messages in neighboring areas. Moreover, it is shown from simulation that the proposed scheme provides the performance gains over the existing Flooding based scheme.

• International conference on construction engineering and project management
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• 2015.10a
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• pp.54-55
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• 2015

Increase of impervious areas due to expansion of housing area, commercial and business building of urban is resulting in property change of stormwater runoff. Also, rapid urbanization and heavy rain due to climate change lead to urban flood and debris flow damage. In 2010 and 2011, Seoul had experienced shocking flooding damages by heavy rain. All these have led to increased interest in applying LID and decentralized rainwater management as a means of urban hydrologic cycle restoration and Natural Disaster Prevention such as flooding and so on. Urban development is a cause of expansion of impervious area. It reduces infiltration of rain water and may increase runoff volume from storms. Low Impact Development (LID) methods is to mimic the predevelopment site hydrology by using site design techniques that store, infiltrate, evaporate, detain runoff, and reduction flooding. Use of these techniques helps to reduce off-site runoff and ensure adequate groundwater recharge. The contents of this paper include a hydrologic analysis on a site and an evaluation of flooding reduction effect of LID practice facilities planned on the site. The region of this Case study is LID Rainwater Management Demonstration District in A-new town and P-new town, Korea. LID Practice facilities were designed on the area of rainwater management demonstration district in new town. We performed analysis of reduction effect about flood discharge. SWMM5 has been developed as a model to analyze the hydrologic impacts of LID facilities. For this study, we used weather data for around 38 years from January 1973 to August 2014 collected from the new town City Observatory near the district. Using the weather data, we performed continuous simulation of urban runoff in order to analyze impacts on the Stream from the development of the district and the installation of LID facilities. This is a new approach to stormwater management system which is different from existing end-of-pipe type management system. We suggest that LID should be discussed as a efficient method of urban disasters and climate change control in future land use, sewer and stormwater management planning.

• Journal of information and communication convergence engineering
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• v.10 no.4
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• pp.329-336
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• 2012

For designing broadcast protocols in mobile ad hoc networks (MANETs), one of the important goals is to reduce the rebroadcast packets redundancy while reaching all the nodes in network. In this paper, we propose a probabilistic broadcasting mechanism based on selfishness and additional coverage in MANETs. Our approach dynamically adjusts the rebroadcast probability according to the extra covered area and number of neighbor nodes. By these two factors, mobile hosts can be classified into three groups: normal, low selfishness, and high selfishness groups. The nodes in the normal group forward packets for other nodes with high probability, whereas the nodes in the low selfishness group rebroadcast packets with low probability and the nodes in the high selfishness group do not rebroadcast packets. We compared our approach with simple flooding and the fixed probabilistic approach. The simulation results show that the proposed schemes can significantly reduce the number of retransmissions by up to 40% compared simple flooding and fixed probabilistic scheme without significant reduction in the network reachability and end-to-end packet delay.

• Journal of the Korea Society of Computer and Information
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• v.21 no.3
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• pp.25-32
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• 2016

Mobile Ad Hoc Networks(MANETs) consists of mobile nodes which communicate with each other without any centralized infrastructure. Message broadcasting by flooding for route discovery in MANET can result in high redundant retransmission, contention and collision of broadcasting packet, known as the broadcast storm problem collectively. The cross-layer design is adopted in this paper, which lets routing layer share the received signal strength information at MAC layer. Also this paper proposes a new probabilistic approach that dynamically adjusts the rebroadcasting probability of a node for routing request packets (RREQs) according to the received signal strength. The simulation results show that the proposed approach demonstrates better performance than blind flooding, fixed probabilistic broadcasting approaches.

• 한국태양에너지학회:학술대회논문집
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• 2011.11a
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• pp.270-273
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• 2011

Water management is important in proton exchange membrane fuel cell because the water balance has a significant impact on the overall fuel cell system performance. In fuel cell vehicle, the vehicle's power demand is dynamic; therefore, the dynamic water management system is required. This present study proposes a method to control the humidity of the input air in cathode side of the fuel cell vehicle. The simulation using several driving cycles shows the proposed air humidification control obtains a relatively good result. The liquid saturation level is seen constant at the target level although still there are small deviations at driving cycles which having averagely high power demands.

• Journal of Communications and Networks
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• v.11 no.3
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• pp.261-270
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• 2009

We propose a tree-based integration of infrastructure networks and MANETs (TUM) to efficiently extend the scope of mobile Internet protocol to mobile ad hoc networks and devise a tree-based routing protocol (TBRP) that is suitable for the TUM architecture. Infrastructure networks have a number of fixed Internet Gateways that connect two heterogeneous networks. Mobile nodes form a number of small trees named pMANETs, each of them growing from anchor node which can communicate directly with an Internet Gateway. A new node registers with foreign agent and home agent along the tree path without resorting to an inefficient flooding. Furthermore, the TBRP sets up a routing path efficiently by exploiting the tree information without relying on flooding. We show by resorting to simulation that our approach is competitive against the conventional AODV based approach.