http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Sensorless Force Control Algorithm based on Momentum Observer Technique
Youngjun Joo,Hanbyeol Kim,Jonghun Park,Changeui Shin,Hoseong Kwak,Joonkeol Song,Chulho Shin 제어로봇시스템학회 2021 제어로봇시스템학회 국제학술대회 논문집 Vol.2021 No.10
This paper presents a sensorless force control algorithm based on external force estimation technique for robotic manipulator systems. Typically, six-axis force torque or joint torque sensors are employed to measure external force induced by contact between the robot and the environment. However, attachment of such sensors to robotic manipulator systems is too costly and requires additional space in the body of a robotic manipulator. Our choice for solving this problem is to employ the momentum observer, which is one of the well-known external force estimation techniques for estimating external force, and the estimated external force is used as feedback for force control without using costly force torque or joint torque sensors. Stability of a closed-loop system where contact is in place and force control performance in such conditions have been analyzed based on the singular perturbation theory. In addition, a design guideline for applying the momentum observer approach we proposed has been put together according to the Lyapunov analysis method. We validate performance of the proposed algorithm using experiments with a six-axis industrial robotic manipulator (Robostar RA004). The experimental results show that the end-effector of the manipulator exerts desired force to contact object with error margin of 3:6%.
거꾸로 수업(Flipped Learning)에 대한 과학 교사의 인식 분석
신영준,하지훈 이화여자대학교 교과교육연구소 2016 교과교육학연구 Vol.20 No.2
본 연구의 목적은 거꾸로 수업의 적용에 대한 시사점을 얻기 위해 초·중·고등학교 교사 100명을 대상으로 거꾸로 수업에 대한 교사의 인식을 파악하여 과학교과에 대한 거꾸로 수업의 적용을 위한 정보를 얻는 데 있다. 이를 위해 전문가 집단을 통해 거꾸로 수업에 대한 교사 인식 문항을 개발하였다. 교사의 인식에 대한 조사 결과 거꾸로 수업에 대한 교사의 이해 정도는 기존 연구(Park & Cha, 2015)에 비해 높아졌으며, 교사들이 과학 교과를 거꾸로 수업 적용이 적절한 교과로 인식하고 있다는 사실도 다시 확인하였다. 거꾸로 수업 도입의 영향과 필요성에서 모두 다소 긍정적인 수준인 보통 이상의 응답을 보였지만, 도입 필요성이 교육에 미치는 영향에 비해 다소 낮은 응답을 나타냈다. 수행 준비 정도에 대해 교사들은 전반적으로 다소 부족하다는 의견을 보였고, 기존 수업에 비해 거꾸로 수업이 더 많은 시간과 노력이 필요하다는 인식을 가지고 있었다. 거꾸로 수업을 성공적으로 수행하기 위해 필요한 능력으로 수업설계능력을 선택한 교사가 가장 많았으며, 학습자료 제작 능력이 그 다음이었다. 이는 Shin et al.(2016a)에서 교사들이 부담을 느꼈던 부분과 일치한다. 이와 같은 연구 결과를 통해 거꾸로 수업의 도입에 대해 교사들의 일반적인 인식은 다소 긍정적이나 실제 적용에 대해 거부감을 가지거나 수행을 위한 준비가 부족하다는 인식을 하고 있음을 알 수 있었다. 과학 교과의 경우 다른 교과에 비해 거꾸로 수업 적용에 대한 교사의 저항은 적을 것으로 예상할 수 있었고, 교사들이 기존 과학 수업의 문제점을 해결할 수 있는 대안으로 거꾸로 수업을 인식하고 있음을 확인할 수 있었다. The purpose of this study was to obtain information on the application of flipped learning and confirm the applicability of flipped learning for science class, through investigating perceptions of 100 teachers in elementary, middle and high school. For this purpose, the questions for teacher’s perceptions about flipped learning were developed by the expert group. The results were as follows : The understanding of flipped learning was higher than in previous studies (Park& Cha, 2015), and the fact that teachers are aware of science as an appropriate subject for the application of flipped learning was confirmed again. Most teachers selected instructional design skills as the most needed ability for successful implementation of flipped learning, which is followed by material production skills. Two skills are related to difficulties presented in Shin et al.(2016a). Based on these results, teachers’ opposition to flipped learning applied in science class is expected to be low, compared to other subjects. It was confirmed that the high applicability of flipped learning may be a solution to the current science class in which teachers’ lecture takes up most part of the lesson.
LES기반 연소모델과 Helmholtz 방정식을 이용한 LIMOUSINE 버너의 연소불안정 해석
신영준(Youngjun Shin),전상태(Sangtae Jeon),김용모(Yongmo Kim) 한국연소학회 2017 한국연소학회지 Vol.22 No.3
This study has numerically investigated the flame—acoustics interactions in the turbulent partially premixed flame field. In the present approach, in order to analyze the combustion instability, the present approach has employed the LES-based combustion model as well as the Helmholtz solver. Computations are made for the validation case of the partially premixed LIMOUSINE burner. In terms of the FFT data, numerical results are compared with experimental data. Moreover, Helmholtz equation in frequency domain is solved by combining CFD field data including the flight time from a nozzle to the flame zone. Based on numerical results, the detailed discussions are made for the essential features of the combustion instability encountered in the partially premixed burner.
정규화(regularization)을 이용한 RMC 영상화 알고리즘의 성능 향상
신영준(Youngjun Shin),김기현(Geehyun Kim),이계민(Gyemin Lee) 대한전자공학회 2016 대한전자공학회 학술대회 Vol.2016 No.6
Detecting orphan radiation sources poses important issues for national security and international nuclear safety. In this paper, we propose an improved image reconstruction algorithm using a regularization method. The proposed algorithm increases the sparsity in the reconstructed RMC images. To demonstrate the proposed algorithm, we performed Monte-Carlo experiments. Our algorithm successfully reduces the artifacts and improves the quality of the RMC images.
수소첨가 천연가스 희박예혼합 연소에 대한 수치해석 연구
신영준(Youngjun Shin),조은성(Eun-Seong Cho) 한국연소학회 2021 한국연소학회지 Vol.26 No.1
Hydrogen enriched LNG flame is tested to understand hydrogen effect on the flame such as temperature, flame speed, emissions (NOx, CO), and extinction at lean premixed (ф=0.4~0.6) various pressure (p=1~25 bar) conditions using CHEMKIN-Pro with GRI 3.0 detailed chemistry. Hydrogen flame temperature is much higher than that of LNG, which may affect high NOx emission production. The flame speed increases with the addition of H₂, so a design speed change should be considered to prevent flashback at the nozzle. The addition of H₂ reduces CO emissions and increases NOx emissions, but can be overcome with a lower equivalent ratio due to the increased flame stabilization due to the addition of H₂. Extinction stretch rate gradually increases with hydrogen addition which shows that enriched hydrogen LNG premixed flame could be sustainable in high turbulent condition which means more stable than LNG itself flame. Even though in 100% H₂ operating condition, gas turbine operating condition shows similar combustion air and exit flue gas flow rate with LNG which means the compressor and turbine may not need major modification.