• KSII Transactions on Internet and Information Systems (TIIS)
• /
• 제10권2호
• /
• pp.522-541
• /
• 2016

Network virtualization provides an effective way to overcome the Internet ossification problem. As one of the main challenges in network virtualization, virtual network embedding refers to mapping multiple virtual networks onto a shared substrate network. However, existing heuristic embedding algorithms evaluate the embedding potential of the nodes simply by the product of different resource attributes, which would result in an unbalanced embedding. Furthermore, ignoring the hops of substrate paths that the virtual links would be mapped onto may restrict the ability of the substrate network to accept additional virtual network requests, and lead to low utilization rate of resource. In this paper, we introduce and extend five node attributes that quantify the embedding potential of the nodes from both the local and global views, and adopt the technique for order preference by similarity ideal solution (TOPSIS) to rank the nodes, aiming at balancing different node attributes to increase the utilization rate of resource. Moreover, we propose a novel two-stage virtual network embedding algorithm, which maps the virtual nodes onto the substrate nodes according to the node ranks, and adopts a shortest path-based algorithm to map the virtual links. Simulation results show that the new algorithm significantly increases the long-term average revenue, the long-term revenue to cost ratio and the acceptance ratio.

• 정보처리학회논문지B
• /
• 제11B권7호
• /
• pp.793-802
• /
• 2004

3차원 가상환경은 시각정보 위주의 제한적인 정보를 제공한다 이는 사용자가 환경 안에서 방향을 상실하게 되는 원인이 된다. 이를 보완하기 위해 여러 가지 방법의 탐색항해 도구에 대한 연구가 진행 되었다. 본 연구에서는 시맨틱 웹 구축 기술의 하나인 토픽맵 기법을 3차원 가상환경에 적용하여 탐색항해 도구를 설계했다. 토픽맵은 토픽과 토픽 사이의 연결 관계를 정의함으로 의미적 연결지도를 구축한다. 이를 적용한 탐색항해 도구의 활용성 실험에서 대표성이 높은 목표 보다는 세밀한 목표를 찾을 때 효과적으로 탐색항해에 도움이 되고 있음을 보여주었다. 또한 찾고자 하는 목표가 정확하지 않은 상태에서의 탐색항해에서 주제에 관련된 주변 지식의 제공은 사용자의 목표 선택에 효과적임을 확인할 수 있었다.

• International Journal of Fuzzy Logic and Intelligent Systems
• /
• 제10권3호
• /
• pp.203-209
• /
• 2010

This paper presents a hierarchical fuzzy motion planner for humanoid robots in 3D uneven environments. First, we define both motion primitives and locomotion primitives of humanoid robots. A high-level planner finds a global path from a global navigation map that is generated based on a combination of 2.5 dimensional maps of the workspace. We use a passage map, an obstacle map and a gradient map of obstacles to distinguish obstacles. A mid-level planner creates subgoals that help the robot efficiently cope with various obstacles using only a small set of locomotion primitives that are useful for stable navigation of the robot. We use a local obstacle map to find the subgoals along the global path. A low-level planner searches for an optimal sequence of locomotion primitives between subgoals by using fuzzy motion planning. We verify our approach on a virtual humanoid robot in a simulated environment. Simulation results show a reduction in planning time and the feasibility of the proposed method.

• 한국정보통신학회논문지
• /
• 제10권5호
• /
• pp.928-933
• /
• 2006

이 논문은 사용자가 2D/3D 공간 데이터를 안전하게 하면서 속성 정보를 공급하는 방식을 활용하여 효과적으로 작동할 수 있는 2D/3D 맵 네비게이션 체계를 구축하는데 목적을 두었다. 이 시스템은 사용자가 검색하는 위치를 2D 또는 3D 방식으로 다양하게 전의 할 수 있도록 지원해 준다. 또한 이 시스템은 고해상도의 조형물 전의가 가능하도록 해줄 뿐만 아니라 기존의 2D/3D에 비해 명칭, 전화 번호, 기타 관련된 정보를 효과적으로 지원해주는 2D/3D 공간 데이터 베이스 기술을 적용하였으며 통합된 2D/3D 공간데이터 베이스 구조를 활용함으로써 다양한 인터페이스의 개발 적용과 더불어 개발 생산성을 향상시켰다.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• 제10권7호
• /
• pp.2892-2913
• /
• 2016

Network virtualization promises to play a dominant role in shaping the future Internet by overcoming the Internet ossification problem. However, due to the injecting of additional virtualization layers into the network architecture, several new security risks are introduced by the network virtualization. Although traditional protection mechanisms can help in virtualized environment, they are not guaranteed to be successful and may incur high security overheads. By performing the virtual network (VN) embedding in a security-aware way, the risks exposed to both the virtual and substrate networks can be minimized, and the additional techniques adopted to enhance the security of the networks can be reduced. Unfortunately, existing embedding algorithms largely ignore the widespread security risks, making their applicability in a realistic environment rather doubtful. In this paper, we attempt to address the security risks by integrating the security factors into the VN embedding. We first abstract the security requirements and the protection mechanisms as numerical concept of security demands and security levels, and the corresponding security constraints are introduced into the VN embedding. Based on the abstraction, we develop three security-risky modes to model various levels of risky conditions in the virtualized environment, aiming at enabling a more flexible VN embedding. Then, we present a mixed integer linear programming formulation for the VN embedding problem in different security-risky modes. Moreover, we design three heuristic embedding algorithms to solve this problem, which are all based on the same proposed node-ranking approach to quantify the embedding potential of each substrate node and adopt the k-shortest path algorithm to map virtual links. Simulation results demonstrate the effectiveness and efficiency of our algorithms.

• 한국컴퓨터정보학회논문지
• /
• 제25권4호
• /
• pp.55-61
• /
• 2020

본 논문에서는 사용자의 경로를 기반으로 가중치 맵을 계산하고, 이를 이용하여 게임이나 가상현실과 같은 인터랙티브 가상 환경에서 논플레이어 캐릭터(Non-playable characters, NPC)의 위치를 효율적으로 제어할 수 있는 방법을 제시한다. 우리의 방법은 사용자의 움직임을 참조하여 NPC에 새로운 경로를 제공하는 네비게이션 메쉬를 자동으로 구성한다. 우리의 방법은 시간이 지남에 따라 사용자가 주로 다니는 길목을 정확하게 찾아내기 때문에 가상환경에 적응형으로 자동 변경이 가능하고, 사용자가 선호하는 경로를 가중치로 스마트 에이전트와 같은 움직임을 만들어 낼 수 있다. 우리는 비디오 게임이나 가상현실과 같은 인터랙티브 환경의 몇 가지 예제 시나리오를 통해 본 논문에서 제안하는 알고리즘의 유용성 테스트를 실험했다. 실제로 우리의 프레임워크는 인터랙티브 환경을 활용하는 모든 유형의 탐색에 쉽게 적용 할 수 있다.

• 한국산업융합학회 논문집
• /
• 제22권4호
• /
• pp.427-433
• /
• 2019

This paper propose a fuzzy inference model for map building and navigation for a mobile robot with an active camera, which is intelligently navigating to the goal location in unknown environments using sensor fusion, based on situational command using an active camera sensor. Active cameras provide a mobile robot with the capability to estimate and track feature images over a hallway field of view. In this paper, instead of using "physical sensor fusion" method which generates the trajectory of a robot based upon the environment model and sensory data. Command fusion method is used to govern the robot navigation. The navigation strategy is based on the combination of fuzzy rules tuned for both goal-approach and obstacle-avoidance. To identify the environments, a command fusion technique is introduced, where the sensory data of active camera sensor for navigation experiments are fused into the identification process. Navigation performance improves on that achieved using fuzzy inference alone and shows significant advantages over command fusion techniques. Experimental evidences are provided, demonstrating that the proposed method can be reliably used over a wide range of relative positions between the active camera and the feature images.

• 한국방재학회:학술대회논문집
• /
• 한국방재학회 2008년도 정기총회 및 학술발표대회
• /
• pp.661-664
• /
• 2008

U-Eco City is promoted nation-wide by development of recent IT technology, method of effective countermeasure disasters, which real-time wire/wireless communication network, and 3D-Web GIS shall be connected that massive database, intelligent service be perceived. U&V-City is the four-dimensional future city that actualizes an intelligent daily ubiquitous computing service by embodying 3D-Virtual City, the reproduction of real world U-City while using Digital map, satellite image, VRML(Virtual Reality Modeling Language), which are presentation tool to describe city components and by efficiently catch and cope about nature and human disasters while employing EAI(External Authoring Interface) that provides HTML&JAVA, and interface for efficient removal/process of massive information/service and also by employing GPS/LBS/Navigation in support of the world-wide orientation concept, and RTLS(Real Time Location System).

• Journal of Ubiquitous Convergence Technology
• /
• 제2권2호
• /
• pp.67-77
• /
• 2008

Representation of various types of information in an interactive virtual reality environment on mobile devices had been an attractive and valuable research in this new era. Our main focus is presenting spatial indoor location sensing information in 3D perception in mind to replace the traditional 2D floor map using handheld PDA. Designation of 3D virtual reality by Virtual Reality Modeling Language (VRML) demonstrates its powerful ability in providing lots of useful positioning information for PDA user in real-time situation. Furthermore, by interpolating portal culling algorithm would reduce the 3D graphics rendering time on low power processing PDA significantly. By fully utilizing the CC2420 chipbased sensor nodes, wireless sensor network was established to locate user position based on Received Signal Strength Indication (RSSI) signals. Implementation of RSSI-based indoor tracking method is low-cost solution. However, due to signal diffraction, shadowing and multipath fading, high accuracy of sensing information is unable to obtain even though with sophisticated indoor estimation methods. Therefore, low complexity and flexible accuracy refinement algorithm was proposed to obtain high precision indoor sensing information. User indoor position is updated synchronously in virtual reality to real physical world. Moreover, assignment of magnetic compass could provide dynamic orientation information of user current viewpoint in real-time.

• 한국전산구조공학회논문집
• /
• 제25권5호
• /
• pp.389-395
• /
• 2012

최근 IT산업 기술의 발전으로 U-City가 전국적으로 추진되는 가운데 유비쿼터스를 효과적으로 구현하기 위해 도시 구성요소 표현 매체인 수치지도(map)와 위성영상, 인터넷 가상세계구현 표준 언어인 VRML(Virtual Reality Modeling Language)를 이용하여 현실세계의 U-City를 그대로 모사한 3차원 3D-가상도시 개념을 정립하였다. 가상도시(V-City)에서는 USN기반의 수많은 데이터베이스 자료와 지능형 서비스정보를 언제 어디서나 상황인지 하기 위하여 실시간 유, 무선 통신 네트워크와 연계시킨 가상도시 개념을 통해, 방대한 양의 유비쿼터스 정보와 서비스를 효율적으로 제어, 처리하기 위한 HTML 자바 애플릿과 인터페이스를 제공하는 EAI(External Authoring Interface)방식을 채용하여 RFID/USN으로 구축된 도시 생활정보를 효율적으로 연동시킴으로써 지능화된 유비쿼터스 컴퓨팅 생활서비스를 구현하는 전 세계 공간 위치 개념의 GPS, LBS, 내비게이션 시간개념의 RTLS와 함께 4차원개념의 유비쿼터스 가상도시(U&V-City) 시스템을 제안하였다.