• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.31 no.10C
• /
• pp.921-926
• /
• 2006

The Presence of a line-of-sight(LoS) blockage can degrade the UWB positioning accuracy for two reasons. Firstly, it makes estimation of the time of arrival(ToA) of the direct path signal difficult by complicating the multipath structure of the propagation channel. Secondly, the higher dielectric constant of the LoS blocking material than that of free space introduces excess propagation delay which will bias the range estimation. In this paper, methods based on ray tracing to reduce the ranging error resulting from the second reason are Posed. We take two different approaches; a statistical approach and a map-aided method. In the statistical approach, we establish a conditional distribution of the excess propagation delay caused by LoS blockages using a ray tracing technique. The lo6wer bound of the ranging performance based on this model is estimated. Ine ray tracing method is also used for the map-aided ToA positioning approach. UWB propagation measurement data taken in an office environment is used to examine the performance of this method.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.21 no.2
• /
• pp.265-276
• /
• 2017

In this paper, a robust and more accurate trajectory tracking control method for a mobile robot is proposed using WIPDC(Weighted Integral Parallel Distributed Compensation) and T-S Fuzzy disturbance observer. WIPDC reduces the steady state error by adding weighted integral term to PDC. And, T-S Fuzzy disturbance observer makes it possible to estimate and cancel disturbances for a T-S fuzzy model system. As a result, the trajectory tracking controller based on T-S Fuzzy disturbance observer shows robust tracking performance. When the initial postures of a mobile robot and the reference trajectory are different, the initial control inputs to the mobile robot become too large to apply them practically. In this study, also, the problem is solved by designing an initial approach path using a path planning method which employs $B\acute{e}zier$ curve with acceleration limits. Performances of the proposed method are proved from the simulation results.

• Proceedings of the KAIS Fall Conference
• /
• 2010.05a
• /
• pp.115-118
• /
• 2010

본 논문은 추적레이더의 추적 오차를 예측하기위한 레이더 시뮬레이터 개발에 관한 것이다. 본 연구에서는 다중경로 전파특성, 표적 모델링, RPY 보상, DTM 지형데이터 등을 이용한 전파의 전파특성 분석을 통한 표적추적레이더의 추적 오차 요인을 분석하였다. 이를 바탕으로 추적 오차를 줄이기 위해 추적 레이더의 서보 특성과 서보 구동의 지연보상을 위한 $\alpha-\beta$ 필터를 사용하였다. 표적 추적레이더의 추적 상황을 종합적으로 고려하여 추적 상황을 정확히 예측할 수 있는 시뮬레이터를 구현 하였다.

• Proceedings of the Korean Society of Fisheries Technology Conference
• /
• 2000.10a
• /
• pp.31-32
• /
• 2000

어군의 이동경로(Priede ＆ Swift, 1993)를 어류 외적인 주변 환경변수와 어류의 내적인 생리생태 등에 따른 행동요인을 고려하여 보다 합리적이고 논리적인 방법으로 어군탐색을 효율적으로 수행할 필요가 있으며, 따라서 어류이동경로 추적에 대한 모델링과 시뮬레이션(Arnolds ＆ Holford, 1995) 기법의 개발이 필요한 실정이다. 따라서 본 연구는 저서성 어류의 이동 궤적에 관한 현장 계측자료를 해양환경요인과 관련시켜 분석하고, 어류이동에 관한 수치행동의 모델링의 주요한 변수를 파악하였다. (중략)

• Proceedings of the KIEE Conference
• /
• 2007.10a
• /
• pp.263-264
• /
• 2007

This paper presents a model predictive controller for tracking control of the wheeled mobile robots (WMRs) subject to nonholonomic constraint. The input-output feedback-linearization method and the mode transformation are used. The performance of the proposed control algorithm is verified via computer simulation. It is shown that the control strategy is feasible.

• Journal of Korea Spatial Information System Society
• /
• v.10 no.2
• /
• pp.25-33
• /
• 2008

The aim of this research was to track the appropriate path favorable to urban development when finding small streams which had been destroyed during the process of urbanization and restoring the streams to a natural flow. This research located the targeted streams in the urban area by using GIS, and designated 3 main factors in restoring small streams: altitude, the usage of land, and land prices. After analyzing the possibilities and outcomes of each factor, the study found the most suitable remedy reflecting those 3 factors. Since there are various effects on stream restoration, based on these 3 factors, the study found and used the most viable factor in accordance with its importance. Using this template, the study developed a method to track the most appropriate restoration path. The study results will contribute to finding, and the restoration of disappeared streams for making more pleasant urban life and an environmentally-friendly city.

• Proceedings of the Korea Contents Association Conference
• /
• 2008.05a
• /
• pp.10-14
• /
• 2008

Computer-animated crowd scenes are often observed in computer games and feature films. The common way to model locomotion of large human crowds is to employ agent based methods where the behavior of each person is independently modeled. But for large crowds, it is difficult for a user to control all the individuals using individual behavior model. Instead, crowd behaviors can be controlled more intuitively at the group level than at the individual level. In this paper, we present the group force field model to simulate path following behavior for groups. A group is a set of characters who have the same goals, i.e. the same path to follow. We also define three characteristics of grouping behavior: alignment, cohesion, and distribution. Our group force field model preserves these characteristics while avoiding collisions. By using our model, user can generate desired group behaviors from line-up behavior to lumped one.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2021.10a
• /
• pp.18-20
• /
• 2021

In order to prevent collision accidents of ships, which has been increasing recently, research on artificial intelligence-based autonomously operated ships (Maritime Autonomous Surface Ship, MASS) is underway. However, most of the studies related to autonomous ships mainly target medium-to-large ships due to the size and cost of the autonomous navigation system, and the sensors used here have a problem in that it is difficult to mount them on small ships. Therefore, this paper provides a path tracking system equipped with GPS and IMU sensors for autonomous operation of small ships. GPS and IMU sensors are utilized to determine the exact position of the vessel, which allows the proposed system to manually control the small vessel model to create a path and then when the small vessel travels the same path. Use the Pure Pursuit algorithm to follow the path. As a result, In this research, it is expected that a lightweight and low-cost sensor can be used to develop an autonomous operation system for small ships at low cost.

• Proceedings of the KAIS Fall Conference
• /
• 2010.11a
• /
• pp.280-283
• /
• 2010

현재 제한적 본인 확인제 실행으로 게시판에 글을 쓰거나 댓글을 달 때 최초 1회에 한하여 본인 인증을 받아야 하기 때문에 사용자는 해당 사이트에 회원가입을 하거나 그에 상응하는 개인정보를 제공해야한다. 이에 정부는 무분별한 주민번호 도용을 막기 위해 주민번호대체수단 의무화를 2007년에 실행하여 아이핀, 공인인증서를 통한 본인확인 대책을 내놓았으나 허술한 본인인증 절차로 인해 아이핀 역시 도용당하고 있는 실정이다. 본 논문에서는 가상 아이디 발급으로 적절한 익명성을 제공함과 동시에 경로 구성 기법을 통하여 악성 댓글 및 의견글 달기를 막기 위한 조건부 추적이 가능한 익명 게시판에 대해서 소개하도록 한다.

• Aerospace Engineering and Technology
• /
• v.11 no.2
• /
• pp.140-148
• /
• 2012

For autonomous navigation, map, pose tracking, and finding the shortest path are required. Because there is no GPS signal in indoor environment, the current position should be recognized in the 3D map by using image processing or something. In this paper, we explain 3D map creation technology by using depth camera like Kinect and pose tracking in 3D map by using 2D image taking from camera. In addition, the mechanism of avoiding obstacles is discussed.