• 제어로봇시스템학회논문지
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• 제21권8호
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• pp.773-780
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• 2015

Navigation in outdoor environments is a fundamental and challenging problem for unmanned ground vehicles. Detecting lane markings or boundaries on the road may be one of the solutions to make navigation easy. However, because of various environments and road conditions, a robust lane detection is difficult. In this paper, we propose a new approach for estimating virtual lanes on a traversable region. Estimating the virtual lanes consist of two steps: (i) we detect virtual road region through road model selection based on traversability at current frame and similarity between the interframe and (ii) we estimate virtual lane using the number of lane on the road and results of previous frame. To improve the detection performance and reduce the searching region of interests, we use a probability map representing the traversability of the outdoor terrain. In addition, by considering both current and previous frame simultaneously, the proposed method estimate more stable virtual lanes. We evaluate the performance of the proposed approach using real data in outdoor environments.

• 대한인간공학회지
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• 제23권1호
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• pp.23-38
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• 2004

This study examines different types of navigation aids when a navigator performs target search tasks in Virtual Environments. The factors manipulated in this study include target information (None/Landmark). navigational difficulty (Easy/Difficult). and map types (None/2D Map/3D Map). Navigation performance was measured by using task completion time and the number of target locations that was remembered by the navigator. In addition, user satisfaction on the navigation aids was also measured by using a 7-point Likert's scale. The results showed that the user satisfaction on the landmark was high when the 3D Map was provided. The task completion time shortened when navigational difficulty was set at "easy." The number of remembered target locations was large when there was no landmark. It was also large with an easy navigation task. or a map (20 or 3D) provided. Guidelines for selecting navigation aids were proposed based on the results.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제11권7호
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• pp.3393-3412
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• 2017

As a main challenge in network virtualization, virtual network embedding problem is increasingly important and heuristic algorithms are of great interest. Aiming at the problems of poor correlation in node embedding and link embedding, long distance between adjacent virtual nodes and imbalance resource consumption of network components during embedding, we herein propose a two-stage virtual network embedding algorithm NA-PVNM. In node embedding stage, resource requirement and breadth first search algorithm are introduced to sort virtual nodes, and a node fitness function is developed to find the best substrate node. In link embedding stage, a path fitness function is developed to find the best path in which available bandwidth, CPU and path length are considered. Simulation results showed that the proposed algorithm could shorten link embedding distance, increase the acceptance ratio and revenue to cost ratio compared to previously reported algorithms. We also analyzed the impact of position constraint and substrate network attribute on algorithm performance, as well as the utilization of the substrate network resources during embedding via simulation. The results showed that, under the constraint of substrate resource distribution and virtual network requests, the critical factor of improving success ratio is to reduce resource consumption during embedding.

• 게임&엔터테인먼트 논문지
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• 제2권1호
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• pp.35-44
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• 2006

본 연구의 목적은 가상현실 분야의 그림 속으로의 여행 기법(TIP, Tour Into the Picture)을 적용하여 운전자가 원하는 목적지까지의 경로를 실시간으로 도로 전경과 동일한 실사기반 3차원 영상으로 보여줄 수 있는 차량용 3차원 네비게이션 시스템을 개발하는데 있다. 이를 위해 기존의 TIP기법을 보완하였고 사용자의 위치와 현재의 도로 상황을 동시에 고려한 최적 경로 탐색기술 등을 제시하였다. 실험 결과, 실제 도로에서 일정 간격을 두고 촬영한 파노라마 실사 영상에 TIP 기법을 적용하여 가상환경을 구축하고 이들 사이의 부드러운 전이를 통해 사진과 같은 품질의 3차원 영상을 보여주었다. 개발된 시스템은 2차원 네비게이션 모듈을 가지며 최적 경로 탐색 및 도로 상황 예측 기능을 제공한다.

• 한국CDE학회논문집
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• 제22권1호
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• pp.89-99
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• 2017

In order to make a virtual endoscopy system effective for exploring the interior of the 3D model of a human organ, it is necessary to generate an accurate navigation path located inside the 3D model and to obtain consistent camera position and pose estimation along the path. In this paper, we propose an approach to virtual navigation of blood vessels, which makes proper use of orthogonal contours and skeleton curves. The approach generates the orthogonal contours and the skeleton curves from the 3D mesh model and its voxel model, all of which represent the blood vessels. For a navigation zone specified by two nodes on the skeleton curves, it computes the shortest path between the two nodes, estimates the positions and poses of a virtual camera at the nodes in the navigation zone, and interpolates the positions and poses to make the camera move smoothly along the path. In addition to keyboard and mouse input, intuitive hand gestures determined by the Leap Motion SDK are used as user interface for virtual navigation of the blood vessels. The proposed approach provides easy and accurate means for the user to examine the interior of 3D blood vessels without any collisions between the camera and their surface. With a simple user study, we present illustrative examples of applying the approach to 3D mesh models of various blood vessels in order to show its quality and usefulness.

• 한국CDE학회논문집
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• 제19권3호
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• pp.272-280
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• 2014

Most of the car navigation systems pzrovide 2D or 3D virtual map-based driving guidance. One of the important issues is how to reduce cognitive burden to the driver who should interpret the abstracted information to real world driving information. Recently, an augmented reality (AR)-based navigation is considered as a new way to reduce cognitive workload by superimposing guidance information into the real world scene captured by the camera. In particular, head-up display (HUD) is popular to implement AR navigation. However, HUD is too expensive to be set up in most cars so that the HUD-based AR navigation is currently unrealistic for navigational assistance. Meanwhile, smartphones with advanced computing capability and various sensors are popularized and also provide navigational assistance. This paper presents a research on cognitive effect and responsiveness of an AR navigation by a comparative study with a conventional virtual map-based navigation on the same smartphone. This paper experimented both quantitative and qualitative studies to compare cognitive workload and responsiveness, respectively. The number of eye gazing at the navigation system is used to measure the cognitive effect. In addition, questionnaires are used for qualitative analysis of the responsiveness.

• 제어로봇시스템학회논문지
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• 제15권3호
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• pp.315-322
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• 2009

This paper explains a control and navigation algorithm of a 6-DOF gait rehabilitation robot, which can allow a patient to navigate in virtual reality (VR) by upper and lower limbs interactions. In gait rehabilitation robots, one of the important concerns is not only to follow the robot motions passively, but also to allow the patient to walk by his/her intention. Thus, this robot allows automatic walking velocity update by estimating interaction torques between the human and the upper limb device, and synchronizing the upper limb device to the lower limb device. In addition, the upper limb device acts as a user-friendly input device for navigating in virtual reality. By pushing the switches located at the right and left handles of the upper limb device, a patient is able to do turning motions during navigation in virtual reality. Through experimental results of a healthy subject, we showed that rehabilitation training can be more effectively combined to virtual environments with upper and lower limb connections. The suggested navigation scheme for gait rehabilitation robot will allow various and effective rehabilitation training modes.

• 전자공학회논문지SC
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• 제45권6호
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• pp.10-15
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• 2008

무인차량의 자율주행성능을 예측하고 분석하기 위해서는 실 환경에서 다양한 주행시험을 수행하여야 한다. 하지만, 무인체계의 특성상 시험안전성과 재현성, 다양한 시험환경의 인위적 제공의 어려움 등 많은 제약이 있다. 따라서, 본 논문에서는 실차량에 적용전에 자율주행성능을 분석하기위한 가상시험환경을 구축하고 감지센서신호를 모의하는 기법을 제안하였다. 또한, 제안된 기법의 타당성을 보이기위해 새롭게 개발된 자율주행 알고리즘에 대한 가상환경 및 센서 모델을 이용한 시뮬레이션을 수행한 결과 그 타당성을 입증하였다.

• 디자인학연구
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• 제16권3호
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• pp.71-80
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• 2003

가상현실 분야는 이제 대중화시대를 맞이하고 있다. 데스크탑 가상현실 산업은 다양한 Web VR 애플리케이션을 중심으로 급속히 성장하고 있는 추세이다. 3차원 가상공간에서 사용자 네비게이션의 수행은 가상의 공간에 설정된 논리적 구조를 인지하고 설정된 상호작용을 이해하며 길을 찾아가는 복잡한 과정이다. 그 것은 사용자가 임으로 설정하는 과정이 아니고 기획단계에서 면밀히 디자인되고 설계된 기술적, 기법적 그리고 개념적 과정인 것이다. 이에 따라 본 논고에서는 3차원 가상공간에서의 상호작용적 네비게이션과 관련된 기술적, 기법적, 그리고 개념적 기초이론들을 총체적으로 고찰하고 있다.

• 한국디자인학회:학술대회논문집
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• 한국디자인학회 2005년도 춘계 학술발표대회 논문집
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• pp.130-131
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• 2005