• Asia pacific journal of information systems
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• 제11권2호
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• pp.79-98
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• 2001

As the average size of web sites gets larger, users tend to experience more severe problems while navigating through the sites. In order to alleviate the navigation-related problems, this paper proposes two new navigation systems based on the spatial metaphor to the navigation in the real world. Prototypes of the two system, Complete Route Navigation(CRN) and Complete Survey Navigation(CSN), were developed and applied to four versions of test bed web sites, which were then used in an experiment to test the effectiveness of the two navigation systems. Results from the experiment indicate that the two systems are indeed effective in aiding users to navigate in a large scale web site, and have more positive impacts when provided together. This paper ends with the limits of the study results and their implications to the development of large-scale web sites.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2022년도 춘계학술대회
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• pp.47-49
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• 2022

Robot navigation has seen a major improvement since the the rediscovery of the potential of Artificial Intelligence (AI) and the attention it has garnered in research circles. A notable achievement in the area was Deep Learning (DL) application in computer vision with outstanding daily life applications such as face-recognition, object detection, and more. However, robotics in general still depend on human inputs in certain areas such as localization, navigation, etc. In this paper, we propose a study case of robot navigation based on deep reinforcement technology. We look into the benefits of switching from traditional ROS-based navigation algorithms towards machine learning approaches and methods. We describe the state-of-the-art technology by introducing the concepts of Reinforcement Learning (RL), Deep Learning (DL) and DRL before before focusing on visual navigation based on DRL. The case study preludes further real life deployment in which mobile navigational agent learns to navigate unbeknownst areas.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제14권8호
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• pp.3270-3294
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• 2020

Some things come easily to humans, one of them is the ability to navigate around. This capability of navigation suffers significantly in case of partial or complete blindness, restricting life activity. Advances in the technological landscape have given way to new solutions aiding navigation for the visually impaired. In this paper, we analyze the existing works and identify the challenges of path selection, context awareness, obstacle detection/identification and integration of visual and nonvisual information associated with real-time assisted mobility. In the process, we explore machine learning approaches for robotic path planning, multi constrained optimal path computation and sensor based wearable assistive devices for the visually impaired. It is observed that the solution to problem is complex and computationally intensive and significant effort is required towards the development of richer and comfortable paths for safe and smooth navigation of visually impaired people. We cannot overlook to explore more effective strategies of acquiring surrounding information towards autonomous mobility.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제15권1호
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• pp.216-239
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• 2021

The present work addresses the challenging problem of coordinating power allocation with interference management in multi-robot networks by applying the promising expansion capabilities of multiple-input multiple-output (MIMO) and full duplex systems, which achieves it for maximizing the throughput of networks under the impacts of Doppler frequency shifts and external jamming. The proposed power allocation with interference coordination formulation accounts for three types of the interference, including cross-tier, co-tier, and mixed-tier interference signals with cluster head nodes operating in different full-duplex modes, and their signal-to-noise-ratios are respectively derived under the impacts of Doppler frequency shifts and external jamming. In addition, various optimization algorithms, including two centralized iterative optimization algorithms and three decentralized optimization algorithms, are applied for solving the complex and non-convex combinatorial optimization problem associated with the power allocation and interference coordination. Simulation results demonstrate that the overall network throughput increases gradually to some degree with increasing numbers of MIMO antennas. In addition, increasing the number of clusters to a certain extent increases the overall network throughput, although internal interference becomes a severe problem for further increases in the number of clusters. Accordingly, applications of multi-robot networks require that a balance should be preserved between robot deployment density and communication capacity.

• 해양환경안전학회:학술대회논문집
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• 해양환경안전학회 2017년도 공동학술발표회
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• pp.96-96
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• 2017

• 한국항행학회논문지
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• 제24권1호
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• pp.16-27
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• 2020

본 논문에서는 위성항법 불용 환경에서의 무인비행체 항법을 위한 광류 정보 활용에 관한 연구 내용을 기술한다. 광류 정보는 위성항법 불용 환경에서 수평 위치 및 속도 추정을 위해 중요한 측정값이므로 정확한 광류 정보의 획득은 필수적이다. 이에 광류 정보에 포함될 수 있는 바이어스를 추정하여 상쇄함으로써 추정 성능을 향상시킬 수 있는 항법 알고리즘을 제안한다. 제안된 알고리즘을 적용하여 검증하기 위해 유도, 항법, 제어 시스템을 설계하여 통합 시뮬레이션 환경을 구축한다. 이를 기반으로 수치 시뮬레이션을 수행하여 제안된 알고리즘을 분석한다.

• 우주기술과 응용
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• 제3권1호
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• pp.58-71
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• 2023

본 논문에서는 관성측정장치와 천측 항법을 활용한 수평 위치 추정을 위한 항법 시스템 설계에 대해 기술하였다. 우주 상에서 별은 천구 상에 널리 퍼져 있는 천체로서 별의 관측을 통해 자세 정보를 획득하는데 주로 사용되어 왔다. 하지만 별의 고도 정보를 통해 수평 위치에 대한 정보 또한 획득이 가능한데, 이는 천측 항법이라고 불리며 예전 항해사들이 바다 위 항해 중에 자기의 위치를 알아내던 원리와 동일하다. 특히 GPS 등의 사용이 불가능한 심우주에서는 비교적 관측이 쉬운 별을 통해 위치에 대한 정보를 획득하는 것이 중요하다. 따라서 본 논문에서는 수평 위치정보를 추정할 수 있는 항법 시스템을 소개하며 측정값을 활용하는 방식에 따라 약결합과 강결합의 두 가지 방식의 시스템을 설계하고자 한다. 시뮬레이션을 통해 설계된 시스템이 올바르게 수평 위치정보를 추정하는지 여부와 함께 약결합과 강결합 방식의 성능을 비교하여 추후 천측 항법을 활용한 항법 시스템 설계에 도움이 되고자 한다.

• 정보와 통신
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• 제10권11호
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• pp.74-84
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• 1993

Hyundai Electronics Industries Corp has developed a navigation system which automatically computes the current position and displays it on the map using GPS(Global Positioning System). This system has such features as follow : searching of destination by means of digital mapping, locating of the present position on the map and detecting of guidance timing through signals from the artificial satellites and vehicle's sensors, and having a few of functions as TV & VTR monitoring, tracing the route, displaying service information which include hotels, restaurants, entertainments, et al. This paper describes the operations and construction of this navigation system.

• 한국전자통신학회논문지
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• 제16권1호
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• pp.135-144
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• 2021

철도 시스템에서는 인프라 기반의 열차 검측시스템을 통해 열차의 위치정보를 획득하는 것이 일반적이다. 하지만 미검출 및 오검출에 의해 잘못된 위치정보가 제공될 수 있으며, 이로 인한 사고를 야기할 수 있는 문제점을 갖고 있다. 따라서 본 연구에서는 센서 기반 복합항법시스템을 사용하여 열차의 위치정보를 제공하는 방법을 제안한다. 그러나 정확한 정보제공을 위해 복합 항법 시스템의 신뢰성을 검증해야 한다. 따라서 본 논문에서는 실 궤적을 기반으로 기준 궤적과 센서 데이터를 생성하고 다양한 시나리오에 따른 복합 항법 시스템의 성능을 실 궤적 상에서 분석할 수 있는 시뮬레이터를 개발한다.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2006년도 International Symposium on GPS/GNSS Vol.2
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• pp.9-14
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• 2006

Galileo is the European Global Navigation Satellite System, under civilian control, and consists on a constellation of medium Earth orbit satellites and its associated ground infrastructure. Galileo will provide to their users highly accurate global positioning services and their associated integrity information. The elements in charge of the computation of Galileo navigation and integrity information are the OSPF (Orbit Synchronization Processing Facility) and IPF (Integrity Processing Facility), within the Galileo Ground Mission Segment (GMS). Navigation algorithms play a key role in the provision of the Galileo Mission, since they are responsible for computing the essential information the users need to calculate their position: the satellite ephemeris and clock offsets. Such information is generated in the Galileo Ground Mission Segment and broadcast by the satellites within the navigation signal, together with the expected a-priori accuracy (SISA: Signal-In-Space Accuracy), which is the parameter that in fault-free conditions makes the overbounding the predicted ephemeris and clock model errors for the Worst User Location. In parallel, the integrity algorithms of the GMS are responsible of providing a real-time monitoring of the satellite status with timely alarm messages in case of failures. The accuracy of the integrity monitoring system is characterized by the SISMA (Signal In Space Monitoring Accuracy), which is also broadcast to the users through the integrity message.