• Title/Summary/Keyword: Driving Part

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Thickness Evaluation of the Aluminum Using Pulsed Eddy Current (펄스 와전류를 이용한 알루미늄 두께 평가)

  • Lee, Jeong-Ki;Suh, Dong-Man;Lee, Seung-Seok
    • Journal of the Korean Society for Nondestructive Testing
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    • v.25 no.1
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    • pp.15-19
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    • 2005
  • Conventional eddy current testing has been used for the detection of the defect-like fatigue crack in the conductive materials, such as aluminum, which uses a sinusoidal signal with very narrow frequency bandwidth, Whereas, the pulsed eddy current method uses a pulse signal with a broad bandwidth. This can allow multi-frequency eddy current testing, and the penetration depth is greater than that of the conventional eddy current testing. In this work, a pulsed eddy current instrument was developed for evaluating the metal loss. The developed instrument was composed of the pulse generator generating the maximum square pulse voltage of 40V, an amplifier controlled up to 52dB, an A/D converter of 16 bit and the sampling frequency of 20 MHz, and an industrial personal computer operated by the Windows program. A pulsed eddy current probe was designed as a pancake type in which the sensing roil was located inside the driving roil. The output signals of the sensing roil increased rapidly wich the step pulse driving voltage かn off, and the latter part of the sensing coil output voltage decreased exponentially with time. The decrement value of the output signals increased as the thickness of the aluminum test piece increased.

A Study on Analysis of R&D Intensity based on Patent Citation Information: Case Study on Self-driving Car of Google (특허인용정보 기반의 연구집중도 분석에 관한 연구: 구글의 자율주행자동차 기술 중심으로)

  • Lee, Junseok;Kim, Jongchan;Lee, Joonhyuck;Park, Sangsung;Jang, Dongsik
    • Journal of the Korean Institute of Intelligent Systems
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    • v.26 no.4
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    • pp.327-333
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    • 2016
  • An autonomous vehicle is a convergence of artificial intelligence and a vehicle which can drive itself while analyzing the real-time situation on a road without a driver. A lot of research achievements have been revealed through the media and Google is considered to be the best leading company in this field. The use of patent information which contains various information such as bibliographic data and information about technologies is a good way to find out the R&D direction of a company and develop a reasonable strategy. This study is aimed at investigating the direction to which Google focuses its R&D capabilities and establishing strategies for technology development. Google's patents about autonomous vehicles were collected and the degree of research bias was analyzed using Social Network Analysis based on citations indicating the quality of a patent. Based on the results, the strategies for technology development was eventually proposed. As a result, it was revealed that Google focused its R&D capabilities on the part of hardware control to make up for its lack of hardware-oriented technologies. As of now, Google obtained remarkable achievements, so it seems reasonable that last-movers consider cooperative research with Google.

Optimal Wrist Design of Wrist-hollow Type 6-axis Articulated Robot using Genetic Algorithm (유전자 알고리즘을 이용한 손목 중공형 6축 수직다관절 로봇의 최적 손목 설계에 관한 연구)

  • Jo, Hyeon Min;Chung, Won Jee;Bae, Seung Min;Choi, Jong Kap;Kim, Dae Young;Ahn, Yeon Joo;Ahn, Hee Sung
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.18 no.1
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    • pp.109-115
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    • 2019
  • In arc-welding applying to the present automobile part manufacturing process, a wrist-hollow type arc welding robot can shorten the welding cycle time, because feedability of a welding wire is not affected by a robot posture and thus facilitates high-quality arc welding, based on stable feeding with no entanglement. In this paper, we will propose the optimization of wrist design for a wrist-hollow type 6-Axis articulated robot. Specifically, we will perform the investigation on the optimized design of inner diameter of hollow arms (Axis 4 and Axis 6) and width of the upper arm by using the simulation of robot motion characteristics, using a Genetic Algorithm (i.e., GA). Our simulations are based on SolidWorks(R) for robot modeling, MATLAB(R) for GA optimization, and RecurDyn(R) for analyzing dynamic characteristics of a robot. Especially RecurDyn(R) is incorporated in the GA module of MATLAB(R) for the optimization process. The results of the simulations will be verified by using RecurDyn(R) to show that the driving torque of each axis of the writs-hollow 6-axis robot with the optimized wrist design should be smaller than the rated output torque of each joint servomotor. Our paper will be a guide for improving the wrist-hollow design by optimizing the wrist shape at a detail design stage when the driving torque of each joint for the wrist-hollow 6-axis robot (to being developed) is not matched with the servomotor specifications.

A Research of Factors Affecting LiDAR's Detection on Road Signs: Focus on Shape and Height of Road Sign (도로표지에 대한 LiDAR 검지영향요인 연구: 도로표지의 모양과 높이를 중심으로)

  • Kim, Ji yoon;Park, Bum jin
    • The Journal of The Korea Institute of Intelligent Transport Systems
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    • v.21 no.4
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    • pp.190-211
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    • 2022
  • This study investigated the effect of the shape and height of road signs on detection performance when detecting road signs with LiDAR, which is recognized as an essential sensor for autonomous vehicles. For the study, four types of road signs with the same area and material and different shapes were produced, and a road driving test was performed by installing a 32Ch rotating LiDAR on the upper part of the vehicle. As a result of comparing the shape of the point cloud and the NPC according to the shape of the road sign, It is expected that a distance of less than 40m is required to recognize the overall shape of a road sign using 32Ch LiDAR, and shapes such as triangles and rectangles are more advantageous than squares in securing the maximum point cloud from a long distance. As a result of the study according to the height of the road sign, At short distances (within 20m), if the height of the sign is raised to more than 2m, it deviates from the vertical viewing angle of the LiDAR and cannot express the complete point cloud shape. However, it showed a negligible effect compared to the near-field height change. These research results are expected to be utilized in the development of road facilities dedicated to LiDAR for the commercialization of autonomous cooperative driving technology.

A Study on Artificial Intelligence Ethics Perceptions of University Students by Text Mining (텍스트 마이닝으로 살펴본 대학생들의 인공지능 윤리 인식 연구)

  • Yoo, Sujin;Jang, YunJae
    • Journal of The Korean Association of Information Education
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    • v.25 no.6
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    • pp.947-960
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    • 2021
  • In this study, we examine the AI ethics perception of university students to explore the direction of AI ethics education. For this, 83 students wrote their thoughts about 5 discussion topics on online bulletin board. We analyzed it using language networks, one of the text mining techniques. As a result, 62.5% of students spoke the future of the AI society positively. Second, if there is a self-driving car accident, 39.2% of students thought it is the vehicle owner's responsibility at the current level of autonomous driving. Third, invasion of privacy, abuse of technology, and unbalanced information acquisition were cited as dysfunctions of the development of AI. It was mentioned that ethical education for both AI users and developers is required as a way to minimize malfunctions, and institutional preparations should be carried out in parallel. Fourth, only 19.2% of students showed a positive opinion about a society where face recognition technology is universal. Finally, there was a common opinion that when collecting data including personal information, only the part with the consent should be used. Regarding the use of AI without moral standards, they emphasized the ethical literacy of both users and developers. This study is meaningful in that it provides information necessary to design the contents of artificial intelligence ethics education in liberal arts education.

The Structural Analysis and Criticism of Geommu (Korean Sword Dance) - Focusing in Literary Works and Music - (검무 구조 분석 시론 - 문헌과 음악을 중심으로 -)

  • Kim, Young-Hee
    • (The) Research of the performance art and culture
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    • no.34
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    • pp.9-42
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    • 2017
  • Of all Geommu(劍舞, Korean sword dance), Gisaeng-Geommu danced by gisaeng(妓生, Korean female entertainers) for private guests and at the royal court. The Sword dance in the late Joseon Dynasty used to be dynamic exuding menacing "sword spirit(劍氣)." Sword dance being transmitted today is more ritualistic and elegant. This study considers Korean sword dance has a core structure and motifs transcending generational differences, and based on this critical thinking, aims to analyze the structure of Korean sword dance. This study analyzed the prose "Geommugi(劍舞記)" by Park Je-ga(朴齊家) and the poem "Mugeompyeonjeongmiin(舞劍篇贈美人)" by Jeong Yak-yong(丁若鏞) out of literary works from the late Joseon Dynasty, and from official records of rituals(笏記), "Geomgimu(Sword Dance, 劍器舞)" and "Geommu" in "Gyobanggayo(敎坊歌謠)." In the introduction part of Sword dance, a dancer appears, bows and performs a hand dance or hansam(汗衫) dance to and fro. In the development part, a dancer meets with a sword but first hesitates to hold it and dances holding swords in both hands. The climax shows expert sword skills and combat scenes. In the conclusion part, the court dance involves a dancer bidding a formal farewell, while the dance for entertainment, a dance throws away the sword to finish. From literature materials, the structure of Korean sword dance could be divided into an introduction, a development, a climax and a conclusion. Based on this, this study analyzed sword dance movements by linking the beats accompanying the current sword dance, in the order of a Yeombul, the traditional Korean ballad Taryeong or Neujeun Taryeong, Jajin Taryeong, Taryeong and Jajin Taryeong. The introduction part includes a Buddhist prayer and the beginning of Taryeong. Dancers appear, and in two rows they dance facing each other. On the slow beat, their dances are relaxed and elegant. The development part is matched with Jajin Taryeong. Dancers sit in front of swords and grab them, and they dance holding a pair of swords. The beat gradually becomes faster, progressing the development of the dance. But then, the slower Taryeong is placed again. The reason behind it is to create a tension for a little while, before effectively reaching a climax by speeding up the tempo again. Moving on to Jajin Taryeong, dancers' movements are bigger and more dynamic. The highly elated Jajin Taryeong shows dance movements at the climax on fast, robust beats. In the conclusion part, the beat is quick-tempo and on the upbeat again on Jajin Taryeong. Driving on without a stop on the exciting Yeonpungdae(燕風臺) melody, dancers standing in a line dance wielding the swords and bow before finishing.

Diminution of Current Measurement Error in Vector Controlled AC Motor Drives

  • Jung Han-Su;Kim Jang-Mok;Kim Cheul-U;Choi Cheol;Jung Tae-Uk
    • Journal of Power Electronics
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    • v.5 no.2
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    • pp.151-159
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    • 2005
  • The errors generated from current measurement paths are inevitable, and they can be divided into two categories: offset error and scaling error. The current data including these errors cause periodic speed ripples which are one and two times the stator electrical frequency respectively. Since these undesirable ripples bring about harmful influences to motor driving systems, a compensation algorithm must be introduced to the control algorithm of the motor drive. In this paper, a new compensation algorithm is proposed. The signal of the integrator output of the d-axis current regulator is chosen and processed to compensate for the current measurement errors. Usually the d-axis current command is zero or constant to acquire the maximum torque or unity power factor in the ac drive system, and the output of the d-axis current regulator is nearly zero or constant as well. If the stator currents include the offset and scaling errors, the respective motor speed produces a ripple related to one and two times the stator electrical frequency, and the signal of the integrator output of the d-axis current regulator also produces the ripple as the motor speed does. The compensation of the current measurement errors is easily implemented to smooth the signal of the integrator output of the d-axis current regulator by subtracting the DC offset value or rescaling the gain of the hall sensor. Therefore, the proposed algorithm has several features: the robustness in the variation of the mechanical parameters, the application of the steady and transient state, the ease of implementation, and less computation time. The MATLAB simulation and experimental results are shown in order to verify the validity of the proposed current compensating algorithm.

The Reliability Design Method According to the Experimental Study of Components and Materials of Railway Rail Fastening System (철도용 레일체결장치 부품.소재의 실험적 연구를 통한 신뢰성 설계 방안)

  • Kim, Hyo-San;Park, Joon-Hyung;Kim, Myung-Ryule;Park, Kwang-Hwa;Lee, Dal-Jae
    • Proceedings of the KSR Conference
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    • 2011.10a
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    • pp.2090-2100
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    • 2011
  • Railway rail fastening system is the critical device which gives big influences to not only the vehicle driving stability and the orbit's structural stability against the impulsive load, but also the noise vibration and the ride comfort. As a part of the low-carbon green growth, the importance of the railroad industry is getting highlights on its excellent energy-efficiency and eco-friendliness. However, so far the Korea's domestic rail fastening system technology is not so good and the technical reliance to abroad is very heavy. In this study, we conducted comparative analysis on the rail fastening system with new and used one of the same type. And those systems are imported by Seoul Metro and are being used by it. With this basis, we developed the components and the materials and then, established the durability assessment methods appropriate to the Korean domestic circumstances. And through the reliability qualification test on the 7 parts of the rail fastening system, we've improved the reliability and guaranteed the 15 years of service lifetime. (B10Life15) Establishment and standardization of Reliability Standard on the parts of the rail fastening system such as anti-vibration pads, guide-plate, screw spike made it possible to perform the internationally fair assessment. And it is thought that we can satisfy the manufactures' and consumers' needs of cost-cutting and qualification security by shortening of assessment period on rail fastening system.

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Study on Vibration and Fatigue Analysis for Plastic Suspension Mat of Automotive Seat (자동차 시트의 플라스틱 서스펜션 매트의 진동과 피로해석에 관한 연구)

  • Choi, Hae-Kyu;Kim, Key-Sun;Kim, Sei-Hwan;Cho, Jae-Ung
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.13 no.2
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    • pp.504-509
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    • 2012
  • Automotive suspension mat is installed at seat back frame. As the back part of passenger is aupported by suspension mat, it is prevented from the pressure concentration. The tired feeling at driving is minimized and the comfortable feeling is increased. In this study, vibration and fatigue are analyzed with plastic suspension mat modelled by 3 Dimension. By the analysis result, the natural frequency becomes 30 Hz with life of 106 cycle and safety factor of 1.6055. Development time and evaluation cost can be cut down by utilizing this analytical technique.

The Tracking Photovoltaic System by One sensor Type (One sensor방식의 추적식 PV System)

  • Ko, Jae-Hong;Park, Jeong-Min
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.13 no.10
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    • pp.4733-4739
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    • 2012
  • While traditional two-axis tracking systems with double sensors had been using two sensors to control azimuth and elevation angle of the sun so that a solar cell module would make a normal line with the sun, this paper proposed a new two-axis system that can achieve the same performance with only one sensor in it. It is Two-axis tracking system that control azimuth and elevation to control to be reduced for solar cell module as proposed tracking system uses 1 sensors and the sun always forms normal. Two-axis tracking system of one sensor method that propose in paper that could reduce electric power consumption and sees than fixed type preventing action and the most efficient driving and needless drive could confirm that generation efficiency of about 23 [%] increases. To heighten efficiency of solar cell doing to receive more sunlights chasing the sun, done tracking device have proceeded a lot of studies in large size way. Therefore, is expected that will do big part in the sun tracking supply through utility study about persistent generation efficiency constructing monitoring system of the sun tracking of this paper.