• The KIPS Transactions:PartC
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• v.17C no.3
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• pp.243-250
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• 2010

Vehicular communication networking is one of the most important building blocks of Intelligent Transportation System (ITS). The vehicular communication network is a wireless communication system enabling vehicles to communicate with each other as well as with roadside base stations. Mobility management of vehicles which move at high speeds and occasionally make a long journey is an interesting research area of vehicular communication networks. Recently, The Proxy Mobile IPv6 (PMIPv6) protocol is proposed for network-based mobility management to reduce the overhead of mobile nodes. PMIPv6 shifts the burden of the mobility management from mobile nodes to network agents to decrease the overhead and latency for the mobility management. In this paper, we derive the scenario of deploying PMIPv6 in vehicular communication networks and propose a new LMA handover mechanism for realizing the scenario. By carrying out the ns-2 based simulations, we verify the operability of the proposed mechanism.

• Journal of the Korean Society for Marine Environment & Energy
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• v.4 no.3
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• pp.65-73
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• 2001

Herein, a theoretical method based on the catenary model Is applied to obtain the tension and drag forces acting on the trash curtain which is deployed at river for the prevention of floating debris inflow into the ocean. Under the assumption that fluid drag is perpendicular to the trash curtain, the tension and drag forces are uniform along the trash curtain. As a numerical model, the trash curtain is moored both symmetrically and asymmetrically with respect to the flow. The tension and drag forces on the trash curtain are investigated according to the change of Bap ratio and inclined angle of the trash curtain. Numerical results show that tension parameter is increased as the gap ratio is increased. It is found that tension parameter is reduced as the inclined angle is increased in the case of asymmetric deployment. The numerical model is applied to the specific problem for the trash curtain (200m) deployed at the Tancheon on the Han river. The maximum inflow velocity that anchor system can endure is 2m/sec.

• Journal of Information Processing Systems
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• v.16 no.5
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• pp.1158-1168
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• 2020

The distance vector-hop wireless sensor node location method is one of typical range-free location methods. In distance vector-hop location method, if a wireless node A can directly communicate with wireless sensor network nodes B and C at its communication range, the hop count from wireless sensor nodes A to B is considered to be the same as that form wireless sensor nodes A to C. However, the real distance between wireless sensor nodes A and B may be dissimilar to that between wireless sensor nodes A and C. Therefore, there may be a discrepancy between the real distance and the estimated hop count distance, and this will affect wireless sensor node location error of distance vector-hop method. To overcome this problem, it proposes a wireless sensor network node location method by modifying the method of distance estimation in the distance vector-hop method. Firstly, we set three different communication powers for each node. Different hop counts correspond to different communication powers; and so this makes the corresponding relationship between the real distance and hop count more accurate, and also reduces the distance error between the real and estimated distance in wireless sensor network. Secondly, distance difference between the estimated distance between wireless sensor network anchor nodes and their corresponding real distance is computed. The average value of distance errors that is computed in the second step is used to modify the estimated distance from the wireless sensor network anchor node to the unknown sensor node. The improved node location method has smaller node location error than the distance vector-hop algorithm and other improved location methods, which is proved by simulations.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.1A
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• pp.65-75
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• 2009

In Wireless Sensor Network, the sensor node localization is important issue for information tracking, event detection, routing. Generally, in wireless sensor network localization, the absolute positions of certain anchor nodes are required based on the use of global positioning system, then all the other nodes are approximately localized using various algorithms based on a coordinate system of anchor DV-Hop is a localized, distributed, hop by hop positioning algorithm in wireless sensor network where only a limited fraction of nodes have self positioning capability. However, instead of uniformly distributed network, in anisotropic network with possible holes, DV-Hop's performance is very low. To address this issue, we propose Group based DV-Hop (GDV-Hop) algorithm. Best contribution of GDV-Hop is that it performs localization with reduced error compared with DV-Hop in anisotropic network.

• KSCI Review
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• v.14 no.1
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• pp.265-271
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• 2006

In this paper, we propose a new automatic fingerprint identification system that identifies individuals in large databases. The algorithm consists of three steps: preprocessing, classification, and matching, in the classification, we present a new classification technique based on the statistical approach for directional image distribution. In matching, we also describe improved minutiae candidate pair extraction algorithm that is faster and more accurate than existing algorithm. In matching stage, we extract fingerprint minutiaes from its thinned image for accuracy, and introduce matching process using minutiae linking information. Introduction of linking information into the minutiae matching process is a simple but accurate way, which solves the problem of reference minutiae pair selection in comparison stage of two fingerprints quickly. This algorithm is invariant to translation and rotation of fingerprint. The proposed system was tested on 1000 fingerprint images from the semiconductor chip style scanner. Experimental results reveal false acceptance rate is decreased and genuine acceptance rate is increased than existing method.

• Proceedings of the KSPS conference
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• 2002.11a
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• pp.123-126
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• 2002

In this paper, we describe our LVCSR system for Korean broadcast news transcription. The main focus is to find the most proper morpheme-based lexical model for Korean broadcast news recognition to deal with the inflectional flexibilities in Korean. There are trade-offs between lexicon size and lexical coverage, and between the length of lexical unit and WER. In our system, we analyzed the training corpus to obtain a small 24k-morpheme-based lexicon with 98.8％ coverage. Then, the lexicon is optimized by combining morphemes using statistics of training corpus under monosyllable constraint or maximum length constraint. In experiments, our system reduced the number of monosyllable morphemes from 52％ to 29％ of the lexicon and obtained 13.24％ WER for anchor and 24.97％ for reporter.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.33B no.3
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• pp.28-37
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• 1996

To reduce an authors burden in hypermedia system that allows non-sequential information the process of creating links must be easy. However, most of the conventional hypermedia systems possess two difficulties. First, the author must go through several troublesome process to create a single link. Secondly, it is not easy to create an anchor in text or other multimedia data. Therefore, in order to support effective construction of hypermedia system the editing environment must provide an easy method to create links. In this paper, to resolve the weaknesses of conventional hypermedia system as mentioned above, an editing tool is developed and implemented to easily create the links of multimedia data. There are three methods in creating links and a user can select a convenient method in given circumstances. And for teh efficient production of nodes composed of multimedia information, we provide an authoring environment to integrate and process those informations.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.04a
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• pp.587-591
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• 1996

Usually triangular patches are used to transfer geometric shape in Rpaid Prototyping CAM system. STL, a list of triangles, is de facto in RP industry. Because STL has no topology data, it can cause errornous results. So, STL should be verified before using. After adding support structures to anchor the part to the platform and to prevent sagging or distortion, slicing and layer by layer manufacturing process are done. But triangular patch is surface model and cannot provide dufficient information on geometry in the above processes. So, geometric modeling is necessary in verifying STL, adding support structures, and slicing. It is natural that triangle based modeling is the best when traingular patches are used as input. Considering support structures, solid and faces coexist in RP process. Therefore non-manifold modeler is required. In this study, triangle based non-manifold geometric modeling is proposed for RP system consitent with STL input.

• International Journal of Railway
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• v.3 no.1
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• pp.1-6
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• 2010

The steel plate-girder bridges with concrete gravity piers have possibilities of overturning by lateral inertial force which can be reproduced by sudden earthquake attack. This paper explores an overturning mechanism of existing concrete gravity pier onto the sandy soil in the event of lateral push-over load by in-situ experimental observation. The in-situ push-over experiment for pier with earth anchors between spread footing and rock beds exhibits a reasonable enhancement of ductility against overturning. In unanchored system, a flexural crack at cold joint of concrete pier is not developed because of the over-turning of the pier. This leads a global instability (rotation) of pier-footing system with relatively low stresses in pier itself. While a lateral load is persistently increased in anchored system, the successive flexural cracking failure at cold joint is observed even after the local shear failure of soil due to redistribution of stress equilibrium between soil and pier structure as long as a tensile action of anchor cable is active.

• Ocean and Polar Research
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• v.41 no.1
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• pp.19-34
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• 2019

The present study obtained universal mathematical models of all elements and characteristics regarding hook and line fishing systems. To describe the hook and line fishing systems on site we used three kinds of coordinate systems: the earth based coordinate system, natural coordinate system, and flow (velocity) coordinate system. Mathematical models presented in this article allow us to define the shape of the fishing gear, the tension of the rope at different points, hydrodynamic resistance, diameter of the hook's wire, immersion depth of the fishing hooks, distance from hooks to the ground and the required lifting force of the floats. These models allow for the performance of computer simulations regarding any kinds of hook and line gears in still water or water where flow occurs.