• Title/Summary/Keyword: motor design

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AUTO-GUIDING SYSTEM FOR CQUEAN (CAMERA FOR QUASARS IN EARLY UNIVERSE)

  • Kim, Eun-Bin;Park, Won-Kee;Jeong, Hyeon-Ju;Kim, Jin-Young;Kuehne, John;Kim, Dong-Han;Kim, Han-Geun;Odoms, Peter S.;Chang, Seung-Hyuk;Im, Myung-Shin;Pak, Soo-Jong
    • Journal of The Korean Astronomical Society
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    • v.44 no.4
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    • pp.115-123
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    • 2011
  • To perform imaging observations of optically red objects such as high redshift quasars and brown dwarfs, the Center for the Exploration of the Origin of the Universe (CEOU) recently developed an optical CCD camera, Camera for QUasars in EArly uNiverse (CQUEAN), which is sensitive at 0.7-1.1 ${\mu}m$. To enable observations with long exposures, we develop an auto-guiding system for CQUEAN. This system consists of an off-axis mirror, a baffle, a CCD camera, a motor and a differential decelerator. To increase the number of available guiding stars, we design a rotating mechanism for the off-axis guiding camera. The guiding field can be scanned along the 10 arcmin ring offset from the optical axis of the telescope. Combined with the auto-guiding software of the McDonald Observatory, we confirm that a stable image can be obtained with an exposure time as long as 1200 seconds.

Launch of PE/$LN_2O$ Hybrid Rocket Vehicle and Analysis of Flight Path (PE/$LN_2O$ 소형 하이브리드 시험발사 및 비행궤도 분석)

  • Lee, Min-Ho;Kim, Jae-Wook;Sin, Jun-Ho;Um, Yong-Kyung;Oh, Yu-Jin;Lee, Sun-Jae;Jung, Young-Kyu;Jo, Jae-Yun;Choi, Young-Rok;Lee, Jung-Pyo;Kim, Jin-Kon
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2010.11a
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    • pp.820-824
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    • 2010
  • The purpose of this study is to develop basic technology of hybrid rocket vehicle by constructed and launched. This small hybrid rocket using HDPE/LN2O and Aluminium steel for its body (weight : 12.5 kg, diameter : 114 mm, height : 1.8 m) was designed. The fuel grain and injector were designed for 50 kgf thrust and burning time 2.5 sec. This rocket was loaded the data acquisition device for obtaining data of pressure and velocity during its flying and equiped an automatic ejector system using spring/motor and timer to collect the rocket more safely after launching. It was launched successfully, but found some problem that the rocket's weight was heavier than expected and the thrust was not enough to reach the designed altitude and analyzed its flight path way.

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Prediction of Lift Performance of Automotive Glass Using Finite Element Analysis (유한요소해석을 통한 자동차용 글라스의 승강성능 예측)

  • Moon, Hyung-Il;Kim, Heon-Young;Choi, Cheon;Lee, In-Heok;Kim, Do-Hyung
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.34 no.11
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    • pp.1749-1755
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    • 2010
  • The performance of power window system was decided by driving characteristics of the window regulator part and reaction by the glass run. The performance of power window system usually has been predicted by experimental methods. In this paper, an analytical method using the explicit code was suggested to overcome the limit of the experimental methods. The friction coefficient of glass run was obtained by the friction test at various conditions and the Mooney-Rivlin model was used. Also, a mechanism of window regulator consisted of the fast belt system and the slip ring elements. And, we conducted the analysis considering characteristic of a motor and obtained the lifting speed of automotive glass with high reliability

Pulsatile Pressure Distribution on the Snubber of Reciprocating Compressor (왕복동식 압축기의 스너버내 맥동압 분포)

  • Lee, Gyeong-Hwan;Rahman, Mohammad-Shiddiqur;Chung, Han-Shik;Jung, Hyo-Min
    • Proceedings of the SAREK Conference
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    • 2007.11a
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    • pp.606-611
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    • 2007
  • Pulsation is an inherent phenomenon in reciprocating compressors. It interacts with piping to cause vibrations and performance problems. Indiscriminately connecting to a compressor can be dangerous and cost money in the form of broken equipment and piping, poor performance, inaccurate metering, unwanted vibration, and sometimes noise. Piping connected to a compressor can materially affect the performance and response. To minimize these detrimental effects, reciprocating compressor system should be equipped by pulsation suppression system. This study discusses pressure pulsation phenomena occurred in a reciprocating compressor system. An experiment applied air compressor unit, as pulsating pressure generator, has been done. The compressor was connected sequentially to a snubber model and pressure tank. Sensor probes were placed on the inlet and outlet pipes of snubber. Compressor was driven by a motor controlled by a frequency regulator. The experiment was conducted by adjusting the regulator at 40Hz. General information about an internal gas flow can be achieved by numerical analysis approach. Information of the velocity, pressure and turbulence kinetic energy distribution are presented in this paper. Based on this result, the design improvement might be done.

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The Effects of Neurofeedback Training on Physical, Psychoemotional Stress Response and Self-Regulation for Late Adolescence: A Non-Randomized Trial (뉴로피드백 훈련이 후기청소년의 신체적, 정서심리적 스트레스 반응과 자기조절에 미치는 효과: 비무작위 연구)

  • Choi, Moon-Ji;Park, Wan-Ju
    • Journal of Korean Academy of Nursing
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    • v.48 no.2
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    • pp.208-220
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    • 2018
  • Purpose: The aim of this study was to analyze the effects of neurofeedback training for reducing stress and enhancing self-regulation in late adolescence to identify the possibility of use for nursing intervention. Methods: A nonequivalent control group pre-post quasi-experimental design was used. Participants were 78 late adolescents assigned to the experimental group (n=39) that received the neurofeedback training and the control group (n=39). Data were collected on heart rate variability (HRV) and skin conductance level (SCL) to assess stress-biomarker response. The questionnaire contained 164 items from: Positive and Negative Affect Schedule (PANAS), Symptom Checklist-90-Revised (SCL-90-R) and Self-regulatory Ability scale. The neurofeedback training was based on the general adaptation syndrome and body-mind medicine. The intervention was conducted in a total of 10 sessions for 30 minutes per session with high-beta, theta and sensory motor rhythm training on scalp at central zero. Results: There were significant difference in standard deviation of normal to normal interval (p=.036) in HRV and SCL (p=.029) of stress-biomarker response between the two groups. Negative affect (p=.036) in PANAS and obsessive compulsive (p=.023) and depression (p<.001) in SCL-90-R were statistically significant. Self-regulation mode (p=.004) in self-regulation ability scale showed a significant difference between the two groups. Conclusion: The results indicated that the neurofeedback training is effective in stress-biomarkers, psychoemotional stress response and self-regulation. Therefore, neurofeedback training using neuroscientific approach based on brain-mind-body model can be used as an effective nursing intervention for late adolescents in clinics and communities for effective stress responses.

Design and Performance Verification of Active Phased Array Antenna Near-Field Scanner with Mobility (이동성을 구비한 능동위상배열안테나 근접전계 스캐너 설계 및 성능 검증)

  • Yoo, Woo-Sung;Kim, Sung-Gyun;Kwon, Yong-Wook;Jung, Gi-Young;Jang, Heon-Soon
    • Journal of IKEEE
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    • v.21 no.1
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    • pp.30-38
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    • 2017
  • It is necessary to check the fault of phased array antenna, when the active phased array radar installed in the site is suspected performance degradation due to external impact or long-term operation. However, the near-field test should be performed in anechoic chamber in order to measure the phased array antenna, so that much time and cost must be applied for radar disassembly and transportation, and the operational availability of the radar system is deteriorates. Therefore, we propose a near-field scanner with mobility to check the fault of the phased array antenna at the site, and the effectiveness of the proposed scanner was verified with ${\pm}0.5dB$ magnitude and ${\pm}1.5^{\circ}$ phase in comparison with measured data in anechoic chamber.

Effect of Aerobic Exercise on Cognitive Functions in Childen and Adolescents : A Review (유산소 운동이 소아 및 청소년의 인지기능에 미치는 영향 : 문헌고찰)

  • Kang, Kyoung Doo;Cho, Jung Hwan;Han, Doug Hyun
    • Journal of the Korean Academy of Child and Adolescent Psychiatry
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    • v.26 no.3
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    • pp.143-148
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    • 2015
  • The purpose of this review was to investigate the relationship between aerobic exercise and cognitive function as well as synthesize the effect of aerobic exercise intervention studies centered on psychiatric symptoms associated with general cognitive deficit. Prospective studies on aerobic exercise and improvement of cognitive function were reviewed and synthesized. In addition, this literature review provides significant positive results on the relationship between aerobic exercise and general cognitive deficit associated with psychiatric symptoms. Review of this literature suggests that there is a positive relationship between participation in aerobic exercise and cognitive function. In this text, there are at least three general pathways by which aerobic exercise may facilitate executive function in children : 1) cognitive demands inherent in engaging in physical activity, 2) cognitive demands inherent in cooperation of complex motor tasks, and 3) physiological changes resulting from aerobic exercise. Another main finding of this review is that physical activity has a stronger influence on cognitive deficit, including attention-deficit hyperactivity disorder, depression, and anxiety. Development of cognitive function is the most important factor for children and youth. Therefore, future research should prove relationship between physical activity and cognitive function using a more scientific and quantitative approach design.

Virtual Flight Test for Conceptual Lunar Lander Demonstrator (달 착륙선 개념설계형상 검증모델 가상비행시험)

  • Lee, Won-Beom;Rew, Dong-Young
    • Aerospace Engineering and Technology
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    • v.12 no.1
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    • pp.87-93
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    • 2013
  • The conceptual design lunar lander demonstrator has been developed to use as a test bed for advanced spacecraft technologies and to test a prototype planetary lander capable of vertical takeoff and landing. Size of the lunar lander demonstrator is the same as that of lunar lander conceptually designed, however, the weight of lunar lander demonstrator is designed in 1/6 scale in consideration of gravity difference between moon and earth. The thruster clustering and virtual flight test were performed in the demonstrator fixed on the ground. The demonstrator ground test has been conducted for two months in the test site for the solid motor combustion of the Goheung Flight Center. The purposes of ground test of demonstrator are to demonstrate and verify essential electronics, propulsion system, control algorithm, embedded software, structure and system operation technologies before developing the flight model lander. This paper is described about the virtual flight test including test configuration, test aims and test facilities

Design of a Transformable Spherical Robot Based on Multi-Linkage Structure (복합 링크 구조 기반의 가변형 구형로봇 설계)

  • Kang, Hyeongseok;Joe, Seonggun;Lee, Dongkyu;Kim, Byungkyu
    • Journal of Aerospace System Engineering
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    • v.11 no.6
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    • pp.26-33
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    • 2017
  • We propose a variable frame structure connected with telescopic mast-shaped shaft for a robot displaying outstanding ability to cross obstacles, and for effective traction control. The wireless control system was built to extend and contract a deployable mechanism, which is shaped into a hoberman sphere assembled with frame structures. In order to develop important parameters for efficient locomotion, we derived an Euler-Lagrange equation for the spherical robot. According to the equation, the DC motor was selected. A prototype mechanism was tested and a Finite-Element Analysis (FEA) was conducted in parallel. Using these data, we constructed a deployable spherical robot with structural stability. The deployable robot moved at a speed of 0.85 m/s from 520 mm to 650 mm.

Development of 3,300V 1MVA Multilevel Inverter using Series H-Bridge Cell (3,300V 1MVA H-브릿지 멀티레벨 인버터 개발)

  • 박영민;김연달;이현원;이세현;서광덕
    • The Transactions of the Korean Institute of Power Electronics
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    • v.8 no.6
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    • pp.478-487
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    • 2003
  • In this paper, a type and special feature of Multi-level inverter used in medium-voltage and high-capacity motor driver is introduced. Especially, a power quality and structural advantages of H-Bridge Multi-level inverter is described. It presented the specific structure of power circuit, design method, controller composition and PWM techniques of the cascaded H-Bridge Multi-level inverter which is developed. The feasibility of the developed product based on 3,300V lMVA 7-level H-bridge inverter was studied by experiments and we get conclusion that 1)generate of near-sinusoidal output voltage; 2)is low dv/dt at output voltage; 3)reduce the harmonic injection at input; Experiment demonstrate that it is very economical in productivity because of using the existing production technique and examination equipment, and has the reliability and a good maintenance due to the structure of Power Cell unit combination as well as low cost IGBT.