Screw based kinematic calibration method for robot manipulators with joint compliance using circular point analysis

Cho, Youngsu,Do, Hyun Min,Cheong, Joono Elsevier 2019 Robotics and computer-integrated manufacturing Vol.60 No.-

<P><B>Abstract</B></P> <P>In this paper, a new kinematic calibration method that takes into consideration the effect of joint compliance in robot manipulators is proposed. A modified product-of-exponential (POE) kinematic model is formulated in such a way that it accommodates static joint deflection by gravitational force. A novel nonlinear cost function is constructed by combining the modified POE kinematic model and the end point measurements of the deflected circular trajectory, so that the kinematic screw and joint compliance are simultaneously identified after minimizing the cost function. An in-depth discussion of how to select a good reference configuration for better parameter identification is also given. Simulation and experimental results are provided to demonstrate the effectiveness of the proposed kinematic calibration method for an industrial 6-DOF (degree-of-freedom) robot manipulator and a custom 9-DOF robot manipulator.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A modified Product-of-Exponential (POE) kinematic model accommodating the effect of joint compliance is proposed. </LI> <LI> A novel nonlinear cost function is constructed by using circular end point measurements to identify the screw and compliance parameters. </LI> <LI> Simulation and experimental results show that the proposed kinematic calibration method enhances the kinematic accuracy of robot manipulators with various ranges of joint compliance. </LI> </UL> </P>

Development of a new 3T1R type cabledriven haptic device

Youngsu Cho,Taewoo Hong,Joono Cheong,Byung-Ju Yi,Whee Kuk Kim,정현환 대한기계학회 2020 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.34 No.11

In this work, structural synthesis of lower-mobility cable-driven parallel mechanisms (CDPMs) is conducted to clearly identify all feasible structures of the lower-mobility CDPMs with n-degrees-of-freedom, which are driven by n + 1 cables fixed on the ground. Through the synthesis, geometric information of various and some new promising structures of unconstrained and constrained lower-mobility CDPMs such as actuation cable wrenches, cable position vector, and required constraint wrenches, are successfully extracted. Then a promising 3T1R type CDPM structure is selected to develop as a haptic device. Its position analysis is conducted and its input-to-output force model is derived. Also, its feasible workspace and its input-to-output force transmission characteristics are examined. Then a prototype haptic device is implemented which is controlled by Raspberry Pi microprocessors. Through a virtual wall following operation by the operator, its operational capability as a haptic device is verified.

GPR based Wi-Fi radio map construction from real/virtual indoor dynamic surveying data

Youngsu Cho,Jooyoung Kim,Myungin Ji,Yangkoo Lee,Sangjoon Park 제어로봇시스템학회 2013 제어로봇시스템학회 국제학술대회 논문집 Vol.2013 No.10

단막극 창작의 교수-학습 방법 연구 : ‘쓰기 전’ 활동을 중심으로

조영수 이화여자대학교 교과교육연구소 2007 교과교육학연구 Vol.11 No.2

본고는 단막극 창작을 위한 교수-학습의 방법과 내용을 실제를 중심으로 하여 연구한 논문이다. ‘희곡 창작’이라 하지 않고 ‘단막극 창작’이라고 한 것은 단막극의 미적 특성이 희곡의 정수(精髓)를 잘 담아내었다고 판단하였으며, 학교 현장의 여러 요건들을 감안한 실제적인 고려가 반영된 때문이다. 이 글에서 제안하는 단막극의 주요한 특징으로는 잘 짜인 구성, 절제된 시적·상징적 표현, 파토스의 세 가지이다. 선정한 단막극의 주요 특징은 전범이 되는 주요 단막극을 통해서 확인하였고, 학생들이 쓴 단막극 대본을 평가하는 척도로 삼았다. 그리고 교수-학습의 구체적인 활동 양상은 직접교수법과 병행한 연극놀이와 드라마 관습의 활동에 의해 소개하였다. 이 중 연행적 활동에 역점을 두었는데, ‘드라마 관습’이라는 활동을 소개하고 이를 활용하여 학생들에게 단막극의 주요 특징들을 이해하도록 하고 창의적 표현을 이끌어 내고자 하였다. 이 논문의 중심 주장은, 학생을 대상으로 한 ‘희곡창작’ 수업에서 창작물의 다양한 실수와 오류를 줄이기 위해서는 ‘쓰기 전’ 활동이 충분히 활성화되어야 한다는 것이다. 이를 검증하기 위해 학생들이 쓴 자료를 분석하고 이를 보완하는 학습활동을 구안하였다. ‘쓰기 전’ 활동은 또 이후 연속된 ‘쓰기’와 ‘공연’ 과정에서의 시행착오나 수정도 상당한 정도로 줄일 수 있다는 것도 제안되었다. 부수적으로는 학생들이 희곡과 연극을 제대로 이해하고 향유하는 것에도 유의미한 영향을 줄 수 있다고 보았다.

Large-Area Cross-Aligned Silver Nanowire Electrodes for Flexible, Transparent, and Force-Sensitive Mechanochromic Touch Screens

Cho, Seungse,Kang, Saewon,Pandya, Ashish,Shanker, Ravi,Khan, Ziyauddin,Lee, Youngsu,Park, Jonghwa,Craig, Stephen L.,Ko, Hyunhyub American Chemical Society 2017 ACS NANO Vol.11 No.4

<P>Silver nanowire (AgNW) networks are considered to be promising structures for use as flexible transparent electrodes for various optoelectronic devices. One important application of AgNW transparent electrodes is the flexible touch screens. However, the performances of flexible touch screens are still limited by the large surface roughness and low electrical to optical conductivity ratio of random network AgNW electrodes. In addition, although the perception of writing force on the touch screen enables a variety of different functions, the current technology still relies on the complicated capacitive force touch sensors. This paper demonstrates a simple and high-throughput bar-coating assembly technique for the fabrication of large area (>20 x 20 cm(2)), highly cross-aligned AgNW networks for transparent electrodes with the sheet resistance of 21.0 Omega sq(-1) at 95.0% of optical transmittance, which compares favorably with that of random AgNW networks (sheet resistance of 21.0 Omega sq(-1) at 90.4% of optical transmittance). As a proof of concept demonstration, we fabricate flexible, transparent, and force-sensitive touch screens using cross-aligned AgNW electrodes integrated with mechanochromic spiropyran-polydirnethylsiloxane composite film. Our force-sensitive touch screens enable the precise monitoring of dynamic writings, tracing and drawing of underneath pictures, and perception of handwriting patterns with locally different writing forces. The suggested technique provides a robust and Powerful platform for the controllable assembly of nanowires beyond the scale of conventional fabrication techniques, which can find diverse applications in multifunctional flexible electronic and optoelectronic devices.</P>

A Study on the Effects of a TETE Class on English Learners’ Motivation and Anxiety

( Youngsu Kim ),( Young Ah Cho ) 대한언어학회 2018 언어학 Vol.26 No.2

The Linguistic Association of Korea Journal, 26(2), 107-131. This study investigates the effects of a TETE (Teaching English through English) class on English learners’ motivation and anxiety based on gender and English proficiency. 207 first-year high school students participated in this study and were assigned to low-, mid-, and high-level groups according to their proficiency. In the study, a background questionnaire, an English motivation questionnaire, an English anxiety questionnaire, and National United Achievement Tests were employed. The results showed that there were no significant differences between the females and the males in the four motivation components, except for the self-determination component, while significant differences were found in all motivation components among the three levels. The findings also revealed that there were significant gender differences in speaking and other types of anxiety, and they were displayed among the levels. Based on these findings, ways for English teachers to lead their TETE classes effectively and their roles in the classes are suggested. Pedagogical implications are also discussed in detail.

The Relationship between Self-efficacy Beliefs and Self-regulated Learning Strategies in Korean EFL Learners

( Cho Young Ah ),( Kim Youngsu ) 대한언어학회 2019 언어학 Vol.27 No.3

The present study analyzes learners' self-efficacy beliefs and self-regulated learning strategy use in an L2 English learning context, mainly focusing on Korean high school students. One-hundred and seventy-three participants were assigned to high-, medium-, and low-proficiency groups. Three instruments were administered, a background questionnaire, the Questionnaire of English Self-Efficacy, and the Questionnaire of English Self-Regulated Learning Strategies. The results reveal that there were significant differences among groups in terms of self-efficacy beliefs for listening, speaking, reading, and writing, showing that high-proficiency learners held a higher sense of self-efficacy than medium- and low-proficiency learners. The study also indicates that there were significant differences among groups when looking at self-regulated learning strategy use. Successful learners employed more self-regulatory skills than others. Additionally, a positive correlation was found between self-efficacy and self-regulation. Based on the results, pedagogical implications are suggested.

AB9: A neural processor for inference acceleration

Cho, Yong Cheol Peter,Chung, Jaehoon,Yang, Jeongmin,Lyuh, Chun-Gi,Kim, HyunMi,Kim, Chan,Ham, Je-seok,Choi, Minseok,Shin, Kyoungseon,Han, Jinho,Kwon, Youngsu Electronics and Telecommunications Research Instit 2020 ETRI Journal Vol.42 No.4

We present AB9, a neural processor for inference acceleration. AB9 consists of a systolic tensor core (STC) neural network accelerator designed to accelerate artificial intelligence applications by exploiting the data reuse and parallelism characteristics inherent in neural networks while providing fast access to large on-chip memory. Complementing the hardware is an intuitive and user-friendly development environment that includes a simulator and an implementation flow that provides a high degree of programmability with a short development time. Along with a 40-TFLOP STC that includes 32k arithmetic units and over 36 MB of on-chip SRAM, our baseline implementation of AB9 consists of a 1-GHz quad-core setup with other various industry-standard peripheral intellectual properties. The acceleration performance and power efficiency were evaluated using YOLOv2, and the results show that AB9 has superior performance and power efficiency to that of a general-purpose graphics processing unit implementation. AB9 has been taped out in the TSMC 28-nm process with a chip size of 17 × 23 ㎟. Delivery is expected later this year.

A 32TFLOPS AI Processor with 1GHz General NN Accelerator

Youngsu Kwon,Yongcheol Peter Cho,Jeongmin Yang,Jaehoon Chung,Kyoung-Seon Shin,Jinho Han,Chan Kim,Chun-Gi Lyuh,Hyun-Mi Kim,Insan Jeon,Min-Seok Choi 대한전자공학회 2019 대한전자공학회 학술대회 Vol.2019 No.6

지역난방 첨두부하보일러 대류부 부식 파손 분석

김영수 ( Youngsu Kim ),채호병 ( Hobyung Chae ),홍민기 ( Minki Hong ),송민지 ( Min Ji Song ),조정민 ( Jeongmin Cho ),김우철 ( Woo Cheol Kim ),하태백 ( Tae Baek Ha ),이수열 ( Soo Yeol Lee ) 한국부식방식학회(구 한국부식학회) 2019 Corrosion Science and Technology Vol.18 No.2

Corrosion failure in the convection part of peak load boiler (PLB) of the district heating system led to water leakage. Herein, Internal Rotary Inspection System (IRIS) inspection was employed to examine wall thinning and the cause of leakage in the flue tube. The corrosive products of the turbulator and tube were investigated using scanning electron microscope combined with energy dispersive spectroscopy, X-ray diffraction, and inductively coupled plasma (ICP). Majority of the serious corrosion damage was observed near the turbulator located in the upper flue tube. ICP analysis of the boiler water revealed oxide formation of sodium chloride in the lower end part of the flue tube. A cross-sectional view of the turbulator revealed the presence of double-layers of the oxide film, indicating environmental change during operation associated with water leakage. The outer surface of the turbulator consisted of the acid oxides such as NO_x and SO_x along with sodium and chloride ions. Dew-point corrosion is hypothesized as the main cause for the formation of acid oxides in the region of contact of the flue tube and the turbulator.