CO₂레이저빔에 의한 이종재질 및 이종두께의 Tailored Blank 용접에 관한 연구

이경돈,유병길,김도훈,황창선 한국레이저가공학회 1999 한국레이저가공학회지 Vol.2 No.3

This research was conducted as a fundamental study to apply tailored blank welding technique into automotive production process. The materials used in this study were 2.0mm thickness low carbon steel sheets and 1.2mm Zn-coated low carbon steel sheets. To ensure the reproducibility and to consider various factors, experiments were conducted by applying Taguchi experimental method with 6 factors. Every welding process was repeated 3 times to offset the effect of uncontrolled factors. Elongation and LDH(Limited Dome Height) were measured to evaluate formability of specimens and Optical microscopy, XRD, SEM, and EDS analysis were performed to observe the microstructures and to determine the solidification mode in the weld. The elongation of specimen welded with optimum condition was 83% of base metal, and LDH was 84% of base metal. In case of laser treated specimen where Zn coating was removed, elongation was 85% of base metal, and LDH was 85% of base metal. In fusion zone, phases were consisted of quasi-polygonal ferrite, banitic ferrite, and martensite.

근접센서를 이용한 자동 두께 측정 시스템

주해호,박현제,정길도,이재원 嶺南大學校 工業技術硏究所 1994 工業技術硏究所論文集 Vol.22 No.2

This paper describes the automatic thickness measurement of the surface grinder for a grinding wheel by application of a proximity sensor, a limit switch, and PLC. The control system is designed to provide feeding a workpiece on the turn-table and pressing it by the upper disk automatically. In the process, the automation of checking the thickness of a grinding wheel is most important. In order to measure the relative displacement, the proximity sensors were employed and the sensitivities of the sensors were investicated and discussed the superiority. It has been shown by model experiment that the automation system of the surface grinder is performed satisfactory.

센서 데이터 및 시간 정보를 융합한 횡단보도 내 보행자 안전 보행 보조 시스템 연구

임신택(Lim, Shin-Teak),박종호(Park, Jong-Ho),정길도(Chong, Kil-To) 한국산학기술학회 2012 한국산학기술학회논문지 Vol.13 No.12

본 연구에서는 다종의 센서 데이터 및 시간 정보를 융합 활용하여 횡단보도 내에서 보행자의 안전 보행을 보조하는 시스템에 대한 설계와 시스템 성능 검증을 통한 안전 보행 보조를 지원하고자 한다. 따라서 설계한 보행자 안전 보조 시스템의 기본 동작 시나리오에 대한 연구 수행 및 시스템 동작을 위한 퍼지 제어를 수행하였고 더불어 환경 인식 및 시간 정보를 적극 활용하기 위하여 각 센서 데이터 처리를 위하여 미디언 필터링을 포함한 필터 처리 를 적극 활용하였고, 이를 바탕으로 시간 정보를 첨부하여 최종적인 시스템 동작 알고리즘을 완성하였다. 추가적으로 활용하고 있는 센서들의 측정값은 기본적으로 불확실성을 내포하고 있기에 센서 결과 데이터를 융합하여 최소한의 신뢰성을 부여하고자 하였으며, 이를 간단한 실험 장비를 이용하여 검증하였다. In this study, by utilizing the information fusion of multi sensor data and time within the crosswalk safety Assistive gait secondary to the safety of pedestrians on the system design and system performance verification through support to. Environmental awareness, and time information in addition to leveraging the default behavior for pedestrian safety design of the secondary system performed a study on the scenario and the behavior of a system for fuzzy control was performed for each sensor data processing, median filtering, including filters processing leveraging, and was attached by the time we complete the final algorithm, the system behavior. In addition, taking advantage of the sensor measurements, so basically uncertainties and sensor results, and you want to give at least the reliability of the data fusion experiment equipment using this simple verification.

Multi-Robots and Robot Sensor Network Applications

Bayanjargal Baasandorj,Kil To Chong(정길도) 제어로봇시스템학회 2014 제어로봇시스템학회 각 지부별 자료집 Vol.2014 No.12

The interaction of distributed robotics and wireless sensor networks has led to the creation of mobile sensor networks. Mobile sensor networks are a class of networks where small sensing devices move in a space over time to collaboratively monitor physical and environmental condition. They are the growing popular class of WSN in which mobility plays a key role in the execution of the application. By introducing mobility to nodes in WSN, we can enhance its capability and flexibility to support multiple mansions and to handle the aforementioned problems. The decreasing costs and the increasing capabilities make mobile sensor networks possible and practical. More and more researches focus on the development of mobile wireless sensor networks (MWSNs) due to its favorable advantages and applications. The research on mobile sensor networks has been plenty worldwide. Robotics can be used in wireless sensor networks to solve many problems such as node repositioning, node localization, acting as data mules, detecting and reacting to sensor failure, aggregate sensor data and even provide mobile battery chargers for the nodes. And also wireless sensor networks can help solve many problems in robotics, such as path planning, robot localization sensing, mapping. Most of the problems in traditional sensor networks may be addressed by incorporating intelligent, mobile robots directly into it. Mobile robots provide the means to explore and interact with the environment in a dynamic and decentralized way. In addition to enabling mission capabilities well beyond those provided by sensor networks, these new systems of networked sensors and robots allow for the development of new solutions to classical problems such as localization and navigation. In this paper we present a overview of multi-robots systems its uses and in the second part reviewed Robotic Sensor network applications.

안전필수(Safety-Critical) 시스템의 실시간 운영체제에 대한 안전성 평가

강영두(Kang, Young-Doo),정길도(Chong, Kil-To) 한국산학기술학회 2010 한국산학기술학회논문지 Vol.11 No.10

원자력발전소의 발전소보호계통과 같은 안전필수 시스템은 예상 가능한 사고로부터 인간과 자연을 보호하기 위한 중요 기능을 수행하는 시스템으로써, 어떠한 조건 하에서도 고유의 안전기능을 안정적으로 수행할 수 있도록 설 계되어야 한다. 원자력발전소의 안전필수 기능을 수행하는 계측제어시스템에 적용되는 최신의 컴퓨터에는 다양한 하 부기기를 감시 및 제어하고, 응용 프로그램을 실행시키기 위한 실시간 운영체제가 탑재되어 있으며, 이러한 실시간 운영체제는 가장 엄격한 소프트웨어 품질이 요구된다. 또한, 예상 가능한 조건에서도 안전필수 시스템의 기능이 적절 히 수행될 수 있도록 설계, 분석 및 평가되어야 한다. 그러나 지금까지 국내 원자력발전소 안전필수 시스템에는, 원자 력 기준과 품질등급에 따라 개발된 제품이 아닌 상용제품의 실시간 운영체제를 정성적 측면에서 승인(Commercial Grade Item Dedication)하는 방식으로 적용되어 왔다. 이로 인해 실시간 운영체제가 안전필수 기능을 수행하는 데 적 합한지를 평가하는 상세 방법론과 경험이 매우 부족한 것으로 파악되고 있다. 특히, 안전필수 시스템에 적용함을 목 적으로 신규 개발되는 실시간 운영체제의 경우, 안전성을 평가하기 위한 적절한 방법을 도출하기에 어려움이 있는 것 으로 파악되고 있다. 본 논문에서는 원전의 안전필수 기능을 수행하는 실시간 운영체제의 설계요구사항을 기반으로, 안전필수 실시간 운영 체제에 대한 안전성 분석 및 평가 사례를 제시하고자 한다. 본 논문에서 제시한 상세 안전성 평가의 방법과 사례는 향후 타 산업분야에서의 안전필수 실시간 운영체제 개발 및 안전성 평가에 활용될 수 있을 것으로 기대된다. Safety-Critical systems, such as Plant Protection Systems in nuclear power plant, plays a key role that the facilities can be operated without undue risk to the health and safety of public and environment, and those systems shall be designed, fabricated, installed, and tested to quality standards commensurate with the importance of the functions to be performed. Computer-based Instrumentation and Control Systems to perform the safety-critical function have Real Time Operating Systems to control and monitoring the sub-system and executing the application software. The safety-critical Real Time Operating Systems shall be designed, analyzed, tested and evaluated to have capability to maintain a high integrity and quality. However, local nuclear power plants have applied the real time operating systems on safety critical systems through Commercial Grade Item Dedication method, and this is the reason of lack of detailed methodology on assessing the safety of real time operating systems, expecially to the new developed one. This paper presents the methodology and experiences of safety evaluation on safety-critical Real Time Operating Systems based upon design requirements. This paper may useful to develop and evaluate the safety-critical Real Time Operating Systems in other industry to ensure the safety of public and environment.

Assessing the Deformity of Cleft Lip Nose Based on Neural Network

Xi, Wang,Vista IV, Felipe,Kim, Deok-Won,Chong, Kil-To 한국정밀공학회 2010 International Journal of Precision Engineering and Vol.11 No.3

The physical appearance of the nostril is important in the objective assessment of a cleft-lip patient while an objective quantitative evaluation is necessary to improve the result of the surgical procedure. The use of Kendall's coefficient of concordance (W) to identify consistency between several raters is proposed in this paper. Linear regression method was then compared with the Neural Network method to find out which is better in determining the consistency of data. The feature factors were extracted from a digital image of the nostril taking into consideration symmetry as the basis. Statistical and Neural Network methods were utilized to process and analyze the deformity assessment data. Two groups of raters were chosen to evaluate the deformity of the cleft lip/cleft nose based on photos shown to them. The angles and distance were measured with respect to the symmetrical aspect and the elementary reference score and factors were obtained through statistical analysis. Linear regression equations describing the relationship between the selected factors and the elementary score were formulated in order to obtain a more reliable reference data. The target data was pre-processed to achieve a more consistent and stable performance. A Neural Network was used to predict the evaluation score and it performed better than the linear regression method under certain conditions. The proposed method can give an objective evaluation to help surgeons evaluate their performance after a surgical procedure and find out if there is a need for further procedures to be done with lesser computational requirement over other existing three-dimensional algorithms.

신경회로망과 PI제어기를 이용한 중수로 핵연료 교체 로봇의 구동압력 제어

임대영(Lim, Dae-Yeong),이창구(Lee, Chang-Goo),김영백(Kim, Young-Baik),김영철(Kim, Young-Chul),정길도(Chong, Kil-To) 한국산학기술학회 2012 한국산학기술학회논문지 Vol.13 No.3

현재 가동 중인 월성 원자력 발전의 핵연료 교체로봇 시스템을 살펴보면 핵연료 교환에 필요한 구동압력 제 어를 위해 PI제어기를 사용한다. PI제어는 구조가 간단하고 이득 설정을 통해 시스템 요구조건에 만족하는 제어 성능 을 낼 수 있지만 밸브와 관로 등의 파라미터 변화로부터 적절한 이득 변경 없이 안정한 제어가 힘들다. 이러한 문제 를 해결하기 위해 PI제어기 이득을 동적으로 변경 하거나 PI제어기 출력을 보상하도록 제어기를 구성하는 것이 바람 직하다. 본 연구개발의 목적은 파라미터 변화에도 안정한 제어가 가능하도록 제어기를 설계하여 오차와 진동현상을 줄이는데 있다. 제안한 PI/NN제어 기법은 PI제어기와 신경회로망 제어기를 병렬 결합한 구조로 신경회로망 제어기가 PI제어기 출력을 보상하여 파라미터 변화에 강인하도록 설계 하였다. 제어기의 성능평가를 위해 직접 실 공정에 테스 트하기가 힘들기 때문에 공정의 특성을 반영하여 모델링한 시뮬레이터를 개발하였고, 시뮬레이션 결과를 실 공정데이 터와 비교하여 공정 특성을 모사함을 보였으며, 파라미터 변화에 PI/NN제어기가 오차 및 진동현상을 줄이는 것을 확 인 하였다. 또한, 실 공정에서 사용 중인 PI제어기를 주 제어기로 사용하면서 파라미터 변화에 대한 비선형성을 보상 하는 제어기 역할을 하기 때문에 신경회로망을 단독으로 사용하였을 때 보다 더 신뢰성 있고 안정적인 제어가 가능 하다. Look into the nuclear power plant of Wolsong currently, it is controlled in order to required operating pressure with PI controller. PI controller has a simple structure and satisfy design requirements to gain setting. However, It is difficult to control without changing the gain from produce changes in parameters such as loss of the valves and the pipes. To solve these problems, the dynamic change of the PI controller gain, or to compensate for the PI controller output is desirable to configure the controller. The aim of this research and development in the parameter variations can be controlled to a stable controller design which is reduced an error and a vibration. Proposed PI/NN control techniques is the PI controller and the neural network controller that combines a parallel and the neural network controller part is compensated output of the controller for changes in the parameters were designed to be robust. To directly evaluate the controller performance can be difficult to test in real processes to reflect the characteristics of the process. Therefore, we develope the simulator model using the real process data and simulation results when compared with the simulated process characteristics that showed changes in the parameters. As a result the PI/NN controller error and was confirmed to reduce vibrations.

A GPS/DR Data Fusion Method Based on the GPS Characteristics for Mobile Robot Navigation

Yuanliang Zhang,Kil To Chong 보안공학연구지원센터 2014 International Journal of Control and Automation Vol.7 No.10

In this paper we have considered the problem of outdoor mobile robot navigation using dead reckoning (DR) system and single GPS receiver. DR is a very simple and practical positioning technique. It is used in various positioning and navigation applications, especially for the mobile robot. DR can provide short term precise navigation information. But its errors will generally accumulate as the mobile robot continues to travel, and the calculated position of the mobile robot will become less and less accurate. For outdoor navigation application, GPS exhibit lots of advantages. It can provide real time and relatively accurate position data in spite of bad weather or other negative factors. But the big errors of civilian used single GPS receiver prevent it from applying to navigation for mobile robot alone. Differential GPS (DGPS) can be used to achieve an error of less than one meter but the costs are prohibitive in terms of commercializing it into the mass market. In this study, a cheap single GPS receiver cooperated with a DR system was used for the navigation system of a outdoors mobile robot in which a new GPS/DR data fusion method was utilized. This proposed fusion algorithm was based on the characteristics of the chosen single GPS receiver. The presented fusion algorithm does not bring much calculation burden and can provide accurate and robust navigation information for the mobile robot by adaptively switching between GPS/DR and DR when GPS lost the satellite signals. Simulation and experiment were performed to validate the effectiveness of the proposed fusion method and the good results showed its potential for outdoors mobile robot navigation.

Variable Parameter Sliding Controller Design for Vehicle Brake with Wheel Slip

Hong Liang,Kil To Chong 대한기계학회 2006 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.20 No.11

In this paper, a 4-wheel vehicle model including the effects of tire slip was considered, along with variable parameter sliding control, pushrod force as the end control parameter, and an antilock sliding control, in order to improve the performance of the vehicle longitudinal response. The variable sliding parameter is made to be proportional to the square root of the pressure derivative at the wheel, in order to compensate for large pressure changes in the brake cylinder. A typical tire force-relative slip curve for dry road conditions was used to generate an analytical tire force-relative slip function, and an antilock sliding control process based on the analytical tire force-relative slip function was used. A retrofitted brake system, with the pushrod force as the end control parameter, was employed, and an average decay function was used to suppress the simulation oscillations. Simulation results indicate that the velocity and spacing errors were slightly larger than the results that without considering wheel slip effect, the spacing errors of the lead and follower were insensitive to the adhesion coefficient up to the critical wheel slip value, and the limit for the antilock control on non-constant adhesion road condition was determined by the minimum of the equivalent adhesion coefficient.

Passive-based Bilateral Controller Design under Varying Time Delay

고영(Ying Gu),정길도(Kil To Chong) 대한전기학회 2009 정보 및 제어 심포지엄 논문집 Vol.2009 No.5

Bilateral teleoperation systems, connected to computer networks such as Internet have to deal with the time delay varying depending on factors such as congestion, bandwidth or distance. And the entire system is easy to become unstable due to irregular time delay. Passivity concept has been using as a framework to solve the stability problem in bilateral control of teleoperation. Acontrol scheme for teleoperation systems with varying time delay is proposed based on a passivity concept is proposed in this paper. One approach makinguse of the characteristic impedagces is proposed to achieve a passive control. Since passive control does not mean that the system performance will be acceptable, another transmission scheme which focuses on both the passive feature and the acceptable performance is configured for varying time delay in this paper. The tracking performance has been proved through the computer simulation for varying time delay bilateral teleoperation system using Matlab Simulink.