• 한국구조물진단유지관리공학회 논문집
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• 제28권3호
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• pp.66-73
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• 2024

사장교에서 케이블 부재는 하중을 전달하는 가장 중요한 부재 중 하나이다. 따라서 사장교의 구조적 상태 및 안정성을 평가하기 위해서는 케이블의 상태를 파악하기 위해 지속적인 모니터링을 수행하는 것이 중요하다. 이러한 모니터링 시스템은 케이블에 부착된 가속도계를 통해 진동을 측정하고 이를 토대로 케이블 장력과 감쇠비를 추정하고, 이를 토대로 케이블의 상태 평가의 기초자료로 활용한다. 이러한 상시 모니터링 시스템은 지속적으로 진동 데이터를 측정하기 때문에 데이터 수집 시스템을 포함한 하드웨어가 안정적이고 전력 효율성이 높아야 한다. 또한 지속적으로 생성되는 대량의 진동 신호들을 사람의 개입을 최소화하며 안정적으로 분석할 수 있는 자율모니터링 시스템이 요구된다. 본 연구에서는 IoT를 활용한 도메인 지식 기반 자율 모니터링 시스템을 개발하였다. 케이블 자율 모니터링 시스템을 구현하기 위한 가장 중요한 요소는 케이블의 장력과 감쇠비의 추정을 위한 진동 신호의 주파수 영역 내 발생하는 첨두의 자동 추정이다. 본 연구에서는 도메인 지식 기반 첨두 자동 추정 알고리즘을 데이터 수집 및 On-Board Processing이 가능한 IoT 시스템에 내장하여 IoT 센서 단에서 Edge computing이 가능한 효율적인 IoT 자율 모니터링 시스템을 구현하였다. 개발된 자율 모니터링 시스템을 국내 사장교에 설치하여 장기간 현장 운영 성능을 평가하였으며, 그 결과 장기 데이터 수신률, 장력 추정의 정확성, 효율성 측면에서 기존 시스템과 비교하여 작동 성능을 확인하고 검증하였다.

• 한국기계가공학회지
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• 제12권1호
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• pp.70-76
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• 2013

Recently, the performance and function of electrical and electronic system in automotive vehicles is developing at a rapid rate with the advancement of IT technologies. Combined together with micro-controller and sensor technologies, the Vehicle Smart System (VSS) being developed to improve driver's convenience and comfort has been employed to a variety of applications. In addition to the convenience system, the Auto-parking Assistance System (AAS) that is now attracting a new attention has been already applied to some vehicles, but it is currently limited to luxury car models only. In this paper, we present a fuzzy controller that enables autonomous parking assistance without the AAS. The controller can perform the assistance with information provided from moving status, current position and steering angle as one is able to park a car based on his/her experience and knowledge for driving and parking. We have evaluated its performance of the proposed controller by simulation and tested the excellence of the controller by building a model vehicle embedded with the micro-controllers.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1997년도 한국자동제어학술회의논문집; 한국전력공사 서울연수원; 17-18 Oct. 1997
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• pp.1589-1592
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• 1997

Among the prerequisite abilities (perception of environment, path planning and position estimation) of an autonomous mobile robot, position estimation has been seldom studied by mobile robot researchers. In most cases, conventional positioin estimation has been performed by placing landmarks or giving the entrire environmental information in advance. Unlikely to the conventional ones, the study addresses a new method that the robot itself can select distinctive features in the environment and save them as landmarks without any a priori knowledge, which can maximize the autonomous behavior of the robot. First, an orjentaion probaility model is applied to construct a lcoal map of robot's surrounding. The feature of the object in the map is then extracted and the map is saved as landmark. Also, presented is the position estimation method that utilizes the correspondence between landmarks and current local map. In dong this, the uncertainty of the robot's current positioin is estimated in order to select the corresponding landmark stored in the previous steps. The usefulness of all these approaches are illustrated with the results porduced by a real robot equipped with ultrasonic sensors.

• 제어로봇시스템학회논문지
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• 제13권8호
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• pp.726-734
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• 2007

Generally, a mobile robot is moved by original input programs. However, it is very hard for a non-expert to change the program generating the moving path of a mobile robot, because he doesn't know almost the teaching command and operating method for driving the robot. Therefore, the teaching method with speech command for a handicapped person without hands or a non-expert without an expert knowledge to generate the path is required gradually. In this study, for easily teaching the moving path of the autonomous mobile robot, the autonomous mobile robot with the function of speech recognition is developed. The use of human voice as the teaching method provides more convenient user-interface for mobile robot. To implement the teaching function, the designed robot system is composed of three separated control modules, which are speech preprocessing module, DC servo motor control module, and main control module. In this study, we design and implement a speaker dependent isolated word recognition system for creating moving path of an autonomous mobile robot in the unknown environment. The system uses word-level Hidden Markov Models(HMM) for designated command vocabularies to control a mobile robot, and it has postprocessing by neural network according to the condition based on confidence score. As the spectral analysis method, we use a filter-bank analysis model to extract of features of the voice. The proposed word recognition system is tested using 33 Korean words for control of the mobile robot navigation, and we also evaluate the performance of navigation of a mobile robot using only voice command.

• Biotechnology and Bioprocess Engineering:BBE
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• 제10권5호
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• pp.400-407
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• 2005

Reverse engineering is defined as the process where the internal structures and dynamics of a given system are inferred and analyzed from external observations and relevant knowledge. The first part of this paper surveys existing techniques for biosystem reverse engineering. Network structure inference techniques such as Correlation Matrix Construction (CMC), Boolean network and Bayesian network-based methods are explained. After the numeric and logical simulation techniques are briefly described, several representative working software tools were introduced. The second part presents our component-based software architecture for biosystem reverse engineering. After three design principles are established, a loosely coupled federation architecture consisting of 11 autonomous components is proposed along with their respective functions.

• International journal of advanced smart convergence
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• 제2권2호
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• pp.10-15
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• 2013

An expert network administrator is not always stationed as disasters happen. In that case, it is desirable that a novice administrator is capable of taking part in network recovery operations as well. In this paper, an agent-based network management system in emergency situations is presented. We use the Active Information Resource based Network Management System (AIR-NMS) to relieve the human administrator from parts of her management tasks and present an interface that remotely can control this management system. The effectiveness of the system is demonstrated by experiments using a prototype system.

• International Journal of Ocean System Engineering
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• 제1권3호
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• pp.120-135
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• 2011

This paper proposes a model based trajectory tracking control scheme for under-actuated underwater robotic vehicles. The difficulty in stabilizing a non-linear system using smooth static state feedback law means that the design of a feedback controller for an under-actuated system is somewhat challenging. A necessary condition for the asymptotic stability of an under-actuated vehicle about a single equilibrium is that its gravitational field has nonzero elements corresponding to non-actuated dynamics. To overcome this condition, we propose a continuous time-varying control law based on the direct estimation of vehicle dynamic variables such as inertia, damping and Coriolis & centripetal terms. This can work satisfactorily under commonly encountered uncertainties such as an ocean current and parameter variations. The proposed control law cancels the non-linearities in the vehicle dynamics by introducing non-linear elements in the input side. Knowledge of the bounds on uncertain terms is not required and it is conceptually simple and easy to implement. The controller parameter values are designed using the Taguchi robust design approach and the control law is verified analytically to be robust under uncertainties, including external disturbances and current. A comparison of the controller performance with that of a linear proportional-integral-derivative (PID) controller and sliding mode controller are also provided.

• 공학교육연구
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• 제24권3호
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• pp.50-57
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• 2021

Although the mathematics education process in AI education is a very important issue, little cases are reported in developing effective methods on AI and mathematics education at the university level. The universities cover all fields of mathematics in their curriculums, but they lack in connecting and applying the math knowledge to AI in an efficient manner. Students are hardly interested in taking many math courses and it gets worse for the students in humanities, social sciences and arts. But university education is very slow in adapting to rapidly changing new technologies in the real world. AI is a technology that is changing the paradigm of the century, so every one should be familiar with this technology but it requires fundamental math knowledge. It is not fair for the students to study all math subjects and ride on the AI train. We recognize that three key elements, SW knowledge, mathematical knowledge, and domain knowledge, are required in applying AI technology to the real world problems. This study proposes a modular approach of studying mathematics knowledge while connecting the math to different domain problems using AI techniques. We also show a modular curriculum that is developed for using math for AI-driven autonomous driving.

• 한국게임학회 논문지
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• 제9권3호
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• pp.139-150
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• 2009

본 논문에서는 가상 에이전트의 행동 계획을 위한 인터렉티브 지식베이스 구축과 인터렉티브 지식베이스를 바탕으로 하는 계획시스템에 관한 방법을 제안한다. 고정적인 지식베이스는 고정적인 계획 수립만 가능하기 때문에 환경의 변화에 잘 대처하지 못한다. 그래서 이 논문에서는 다양한 환경에서 적용이 가능한 인터렉티브한 지식베이스의 구축과 인터렉티브 지식베이스를 활용할 수 있는 인공지능 계획시스템을 제안한다. 본 연구에서 제안한 인터렉티브 지식베이스는 동기, 행동, 사물, 실행의 4가지로 이루어지며 지식베이스의 입력과 지식베이스들 사이의 연관관계는 개발된 자동화 툴을 사용하여 설정한다. 이 툴을 사용하여 사용자는 쉽게 지식베이스에 구성요소들을 추가 또는 수정할 수 있다. 이 지식베이스를 바탕으로 캐릭터는 행동가능한 모든 항목들을 계획을 세우게 되며 이 중 한 가지를 선택하여 행동을 하게 된다. 후에 캐릭터의 환경이 변하게 되더라도 지식베이스의 업데이트를 통해 새로운 행동을 적용시킬 수가 있기 때문에 가상현실 콘텐츠제작자의 입장에서는 상당히 유용하다. 본 논문에서는 확장성이 있는 인터렉티브 지식베이스 구성요소와 구성요소들 사이의 관계설정 그리고 이를 쉽게 입력할 수 있는 툴과 인터렉티브 지식베이스에 적합한 계획시스템의 알고리즘을 제안하여 가상도서관이라는 가상환경에서 실험을 통해 결과를 검증하였다.

• International Journal of Fuzzy Logic and Intelligent Systems
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• 제10권3호
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• pp.210-217
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• 2010

This paper presents integrated path planning and collision avoidance for an omni-directional mobile robot. In this scheme, the autonomous mobile robot finds the shortest path by the descendent gradient of a navigation function to reach a goal. In doing so, the robot based on the proposed approach attempts to overcome some of the typical problems that may pose to the conventional robot navigation. In particular, this paper presents a set of analysis for an omni-directional mobile robot to avoid trapped situations for two representative scenarios: 1) Ushaped deep narrow obstacle and 2) narrow passage problem between two obstacles. The proposed navigation scheme eliminates the nonfeasible area for the two cases by the help of the descendent gradient of the navigation function and the characteristics of an omni-directional mobile robot. The simulation results show that the proposed navigation scheme can effectively construct a path-planning system in the capability of reaching a goal and avoiding obstacles despite possible trapped situations under uncertain world knowledge.