• Journal of KIISE:Information Networking
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• v.29 no.3
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• pp.314-323
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• 2002

The routing protocols designed for wired networks can hardly be used for mobile ad-hoc networks due to limited bandwidth of wireless transmission and unpredictable topological change. Recently, several routing protocols for mobile ad-hoc networks have been Proposed. However, when theme protocols are applied to support real time services like multimedia transmission, they still have problems in ad-hoc networks, where the topology changes drastically. In this paper, we propose a new route selection algorithm which selects the most reliable route that is impervious to route failures by topological changes by mobile hoots. For reliable route selection, the concept of virtual zone (stable zone and caution zone) is proposed. The zone is located in a mobile node'transmission range and determined by mobile node's mobility information received by Global Positioning System (GPS). The proposed algorithm is applied to the route discovery procedure of the existing on-demand routing protocol, AODV, and evaluated by simulation in various traffic conditions and mobility patterns.

• Journal of KIISE:Information Networking
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• v.29 no.3
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• pp.224-232
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• 2002

The routing protocols designed for wired networks can hardly be used for mobile ad-hoc networks due to limited bandwidth of wireless transmission and unpredictable topological change. Recently, several routing protocols for mobile ad-hoc networks have been proposed. However, when these protocols are applied to support real time services like multimedia transmission, they still have problems in ad-hoe networks, where the topology changes drastically. In this paper, we propose a new route selection algorithm which selects the most reliable rouse that is impervious to route failures by topological changes by mobile hosts. For reliable route selection, the concept of virtual zone (stable lone and caution zone) is proposed. The lone is located in a mobile node's transmission range and determined by mobile node's mobility information received by Global Positioning System (GPS). The proposed algorithm is applied to the route discovery procedure of the existing on-demand routing protocol, AODV, and evaluated by simulation in various traffic conditions and mobility patterns.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.15 no.10
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• pp.2157-2163
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• 2011

In this paper, we designed 2D, 2.5D cloth design system and a 3D cloth animation system. They make the 3D cloth animation possible by using coordinate points extracted from 2D and 2.5D cloth design system in order to realize a system that allows customers to wear clothes in the virtual space. To make natural draping, it uses for description the mesh creation and transformation algorithms, path extraction algorithm, warp algorithm, and brightness extraction and application algorithms. The coordinate points extracted here are received as text format data and inputted as clothing information in the cloth file. Moreover, the cloth file has a 2D pattern and is realized to be used in the 3D cloth animation system. The 3D cloth animation system generated in this way builds a web-based fashion mall using ISB (Internet Space Builder) and lets customers view the clothing animation on the web by adding the animation process to the simulation result.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.4C
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• pp.308-315
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• 2002

Guaranteed frame rate (GFR) service has been defied to provide minimum cell rate (MCR) guarantees for virtual connections (VCs) carrying Internet traffic in ATM networks and allow them to fairly share residual bandwidth. The simplest switch implementation mechanism to support the GFR service in ATM networks consists of the frame-based generic cell rate algorithm (F-GCRA) frame classifier and the early packet discard (EPD)-like buffer acceptance algorithm in a single FIFO buffer. This mechanism is simple, but has foiled to guarantee the same bandwidth as an MCR to a VC that has reserved a relatively large MCR. This paper applies the packet spacing scheme to TCP traffic to alleviate its burstness, so as to guarantee a larger MCR to a VC. In addition, the random early detection (RED) scheme is added to the buffer acceptance algorithm in order to improve fairness in use of residual bandwidth. Simulation results show that the applied two schemes improve a quality of service (QoS) in the GFR service for the TCP traffic.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.4A
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• pp.377-385
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• 2010

In this paper, we propose a SInk-initiated geographic Multicast (SIM) protocol to reduce frequent location updates from mobile sinks to a source and to achieve fast multicast tree construction and data delivery. The proposed protocol allows sinks to construct their own data delivery paths to a source node and a multicast tree to be atomically constructed by merging the paths. Then, the source forwards data to the destinations down the multicast tree. This paper also propose a round-based virtual infrastructure with a radial shape for increasing the merging probability of data delivery paths and reducing reconstruction ratio of the multicast tree due to mobility of sinks. Simulation results show that the proposed protocol is superior to previous SOurce-initiated geographic Multicast (SOM) protocols in term of average data delivery delay and average energy consumption.

• Journal of Digital Contents Society
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• v.16 no.1
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• pp.127-135
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• 2015

The development of stereoscopic display hardwares and 3D authoring softwares expands its application areas from particular virtual simulation applications to general movies, games, advertising applications. However, the binocular-based 3D stereoscopic images cause fatigue to viewers. Recent performed many research results about the binocular stereoscopy's depth perception and viewers' fatigue are derived from experimental users studies. In some results, watching and making guidelines for 3D stereoscopic imaging contents are introduced. The 3D stereoscopic-related contents have the contradictory aspects, which are audiences' pursuit of a tolerable minimum fatigue and producer's its of excessive depth changes for providing viewers' immersion. This paper provides user experiments and analysis data in aspects of 3D depth changes. For use of producers, a safety zone and translational velocity of 3D depth changes are introduced. Also, on the viewer side, we present the depth change adaptation time by using an EEG device.

• Journal of the Korean Solar Energy Society
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• v.29 no.2
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• pp.31-38
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• 2009

This study was conducted to forecast inner water temperature strata change by extracting deep water from a dam. For the methodology, the scope wherein the balance between the volume of low-temperature water intake through the virtual water intake opening as installed within the stored water area and the volume of water intake from the surrounding area is not destroyed was calculated through the CFD simulation technique using the computational fluid dynamics(CFD) interpretation method. This study suggested a supplementary method(diffuser) to avoid destroying the water temperature strata, and the effect was reviewed. In case of intake of the same volume, when the velocity of flow of water intake is reduced by increasing the pipe diameter, the destruction of water temperature strata can be minimized. When the area(height) where the intake of water is possible is low, a diffuser for interrupting the vertical direction inflow should be installed to secure favorable water intake conditions in case of water intake on the upper part. This study showed that there was no problem if the intake-enabled, low-temperature area was secured approximately 10m from the bottom when the scope that does not destroy the water temperature strata in case of water intake was forecast using the regression formula.

• Journal of the Korean Society of Marine Environment & Safety
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• v.22 no.7
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• pp.807-813
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• 2016

The Maritime Traffic Safety Audit Scheme was institutionalized in 2009 to provide for professional surveys, measurement and the evaluation of navigational hazards that might occur in coastal waters in the course of marine work. Related researches that dealt with the reform of the Maritime Traffic Safety Audit Scheme found that there were no rules or regulations for verifying whether marine work conformed to audit results and reviewing the exactitude of ship handling simulations which were a crucial part of the scheme. According to the necessity of adopting an ex post facto management system in the field of maritime traffic, this study analyzed the similar audit acts such as the Natural Environment Impact Audit Scheme and the Road Traffic Safety Audit Scheme, and proposed specific articles for revising Maritime Safety Act in order to break out from the institutional inertia of the current Maritime Traffic Safety Audit Scheme. It is expected that a newly proposed legal system for verifying the performance of audit results and the exactitude of audits will help improve maritime traffic safety by eradicating potentially hidden hazards related to marine work.

• Journal of the Korea Society of Computer and Information
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• v.10 no.1 s.33
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• pp.181-188
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• 2005

Chinese Postman Problem (CPP) is a problem that finds a shortest tour traversing all edges or arcs at least once in a given network. The Chinese Postman Problem on Mixed networks (MCPP) is a Practical generalization of the classical CPP and it has many real-world applications. The MCPP has been shown to be NP-complete. In this paper, we transform a mixed network into a symmetric network using virtual arcs that are shortest paths by Floyd's algorithm. With the transformed network, we propose a Genetic Algorithm (GA) that converges to a near optimal solution quickly by a multi-directional search technique. We study the chromosome structure used in the GA and it consists of a path string and an encoding string. An encoding method, a decoding method, and some genetic operators that are needed when the MCPP is solved using the Proposed GA are studied. . In addition, two scaling methods are used in proposed GA. We compare the performance of the GA with an existing Modified MDXED2 algorithm (Pearn et al. , 1995) In the simulation results, the proposed method is better than the existing methods in case the network has many edges, the Power Law scaling method is better than the Logarithmic scaling method.

• Journal of KIISE
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• v.43 no.9
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• pp.1026-1033
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• 2016

Path-finding on a grid map is a problem generally addressed in the fields of robotics, intelligent agents, and computer games. As technology advances, virtual game worlds tend to be represented more accurately and more realistically, resulting in an excessive increase in the number of grid tiles and in path-search time. In this study, we propose a path-finding algorithm that allows a prompt response to real-time queries by constructing a reduced state space and by precomputing all possible paths in an offline preprocessing stage. In the preprocessing stage, we vertically decompose free space on the grid map, construct a connectivity graph where nodes are the decomposed regions, and store paths between all pairs of nodes in matrix form. In the real-time query stage, we first find the nodes containing the query points and then retrieve the corresponding stored path. The proposed method is simulated for a set of maps that has been used as a benchmark for grid-based path finding. The simulation results show that the state space and the search time decrease significantly.