• Title/Summary/Keyword: Rotation performance

Search Result 1,252, Processing Time 0.029 seconds

Fabrication of a Mach-Zehnder interferometer for education using a rotating glass plate and a 3D printer (회전 유리판과 3D 프린터를 이용한 교육용 마흐젠더 간섭계 제작)

  • Jang, Seong-Hun;Ju, Young-G
    • Korean Journal of Optics and Photonics
    • /
    • v.28 no.5
    • /
    • pp.213-220
    • /
    • 2017
  • This paper proposes how to fabricate an educational Mach-Zehnder interferometer that is easy to align and inexpensive, using 3D printers and semiconductor lasers. The interferometer consists of a body $165mm{\times}120mm{\times}57mm$ in size, mirror mounts, a laser holder, beam splitters, and so on. The laser path is adjusted by 4 mirror mounts, each comprised of rubber bands, small metal wires, and a screw. The interference fringe is enlarged by the lens at the final stage. The refractive index of a slide glass was measured by counting the number of moving interference fringes while the slide glass, inserted into one of the two interferometer arms, is rotating. The formula for the refractive index as a function of the optical-path difference and rotation angle was obtained, and used to calculate the refractive index of glass from the interferometer experiment. The use of a rotating glass in one arm of the interferometer nullifies the need for a precision stage, which despite its high cost is often required to observe the moving interference fringe in the classroom. Therefore, the 3D-printed Mach-Zehnder interferometer proposed in this paper can be very useful for education, because of its affordability and performance. It enables students to perform both qualitative and quantitative studies using a 3D-printed interferometer, such as measuring the refractive index of a glass sample, and the wavelength of light.

Scan Matching based De-skewing Algorithm for 2D Indoor PCD captured from Mobile Laser Scanning (스캔 매칭 기반 실내 2차원 PCD de-skewing 알고리즘)

  • Kang, Nam-woo;Sa, Se-Won;Ryu, Min Woo;Oh, Sangmin;Lee, Chanwoo;Cho, Hunhee;Park, Insung
    • Korean Journal of Construction Engineering and Management
    • /
    • v.22 no.3
    • /
    • pp.40-51
    • /
    • 2021
  • MLS (Mobile Laser Scanning) which is a scanning method done by moving the LiDAR (Light Detection and Ranging) is widely employed to capture indoor PCD (Point Cloud Data) for floor plan generation in the AEC (Architecture, Engineering, and Construction) industry. The movement and rotation of LiDAR in the scanning phase cause deformation (i.e. skew) of PCD and impose a significant impact on quality of output. Thus, a de-skewing method is required to increase the accuracy of geometric representation. De-skewing methods which use position and pose information of LiDAR collected by IMU (Inertial Measurement Unit) have been mainly developed to refine the PCD. However, the existing methods have limitations on de-skewing PCD without IMU. In this study, a novel algorithm for de-skewing 2D PCD captured from MLS without IMU is presented. The algorithm de-skews PCD using scan matching between points captured from adjacent scan positions. Based on the comparison of the deskewed floor plan with the benchmark derived from TLS (Terrestrial Laser Scanning), the performance of proposed algorithm is verified by reducing the average mismatched area 49.82%. The result of this study shows that the accurate floor plan is generated by the de-skewing algorithm without IMU.

A Study on Point Cloud Generation Method from UAV Image Using Incremental Bundle Adjustment and Stereo Image Matching Technique (Incremental Bundle Adjustment와 스테레오 영상 정합 기법을 적용한 무인항공기 영상에서의 포인트 클라우드 생성방안 연구)

  • Rhee, Sooahm;Hwang, Yunhyuk;Kim, Soohyeon
    • Korean Journal of Remote Sensing
    • /
    • v.34 no.6_1
    • /
    • pp.941-951
    • /
    • 2018
  • Utilization and demand of UAV (unmanned aerial vehicle) for the generation of 3D city model are increasing. In this study, we performed an experiment to adjustment position/orientation of UAV with incomplete attitude information and to extract point cloud data. In order to correct the attitude of the UAV, the rotation angle was calculated by using the continuous position information of UAV movements. Based on this, the corrected position/orientation information was obtained by applying IBA (Incremental Bundle Adjustment) based on photogrammetry. Each pair was transformed into an epipolar image, and the MDR (Multi-Dimensional Relaxation) technique was applied to obtain high precision DSM. Each extracted pair is aggregated and output in the form of a single point cloud or DSM. Using the DJI inspire1 and Phantom4 images, we can confirm that the point cloud can be extracted which expresses the railing of the building clearly. In the future, research will be conducted on improving the matching performance and establishing sensor models of oblique images. After that, we will continue the image processing technology for the generation of the 3D city model through the study of the extraction of 3D cloud It should be developed.

Polarimetry of solar system small bodies using the Seoul National University 61cm telescope and TRIPOL

  • Jin, Sunho;Ishiguro, Masateru;Kwon, Yuna Grace;Geem, Jooyeon;Bach, Yoonsoo P.;Seo, Jinguk;Sasago, Hiroshi;Sato, Shuji
    • The Bulletin of The Korean Astronomical Society
    • /
    • v.44 no.1
    • /
    • pp.64.2-64.2
    • /
    • 2019
  • It is known that lights scattered by comets and asteroids are partially polarized. From polarimetric observations of those objects, we can investigate physical properties, such as albedos, sizes of cometary dust particles and regolith of asteroids. Since the polarization degrees of those objects highly depend on their phase angles (Sun-object-observer's angles), long-term monitoring observations are required. Moreover, comets show unforeseeable activations (i.e., outbursts) which need follow-up observations to understand the mechanism. In order to realize such monitoring and transient observations, we installed the Triple-Range Imager and POLarimeter (TRIPOL) on the 61cm telescope of Seoul National University (Hereafter, SNU) Gwanak campus. With this combination, we can obtain g', r', i' bands photopolarimetric images simultaneously with $8.0^{\prime}{\times}8.0^{\prime}$ field of view and pixel resolution of 0.94" pixel-1. Here, we make a presentation regarding the photometric and polarimetric performances of TRIPOL on the SNU 61cm telescope. In addition, we introduce initial polarimetric results of asteroid and comets with the instruments. First, we determine the limiting magnitudes (defined as magnitudes for S/N=5) of $15.17{\pm}0.06$ (g'-band), $15.68{\pm}0.01$ (r'-band), $16.24{\pm}0.03$ (I'-band), respectively, with total 240-seconds exposure (four 60-seconds exposure images, each was taken at different rotation angle for the half-wave plate). Second, we found that the instrumental polarization is negligibly small, ($-0.32{\pm}0.04%$ in the g', $-0.36{\pm}0.05%$ in the r' and $-0.21{\pm}0.04%$ in the i'-bands), while the polarization efficiencies are large enough to maximize the performance (i.e., $97.52{\pm}0.03%$ in the g', $98.83{\pm}0.02%$ in the r' and $99.15{\pm}0.02%$ in the i'-bands). With the instruments, we made observations of three Jupiter-family comets, 21P/Giacobini-Zinner, 38P/Stephan-Oterma, and 46P/Wirtanen and plan to observe one near-Earth asteroid, (433) Eros, on a trial basis. Especially for comets, we discriminate signals from dust and gas to eliminate gas contamination, which are known to change observed degree of linear polarization, using multi-band images. We confirm that the phase angle dependency of these comets are consistent with previous observations, probably because polarimetric property of Jupiter-family comets are broadly homogeneous unlike asteroids. We will also describe future observation plans using TRIPOL and SNU 61cm telescope.

  • PDF

Development of Convolutional Network-based Denoising Technique using Deep Reinforcement Learning in Computed Tomography (심층강화학습을 이용한 Convolutional Network 기반 전산화단층영상 잡음 저감 기술 개발)

  • Cho, Jenonghyo;Yim, Dobin;Nam, Kibok;Lee, Dahye;Lee, Seungwan
    • Journal of the Korean Society of Radiology
    • /
    • v.14 no.7
    • /
    • pp.991-1001
    • /
    • 2020
  • Supervised deep learning technologies for improving the image quality of computed tomography (CT) need a lot of training data. When input images have different characteristics with training images, the technologies cause structural distortion in output images. In this study, an imaging model based on the deep reinforcement learning (DRL) was developed for overcoming the drawbacks of the supervised deep learning technologies and reducing noise in CT images. The DRL model was consisted of shared, value and policy networks, and the networks included convolutional layers, rectified linear unit (ReLU), dilation factors and gate rotation unit (GRU) in order to extract noise features from CT images and improve the performance of the DRL model. Also, the quality of the CT images obtained by using the DRL model was compared to that obtained by using the supervised deep learning model. The results showed that the image accuracy for the DRL model was higher than that for the supervised deep learning model, and the image noise for the DRL model was smaller than that for the supervised deep learning model. Also, the DRL model reduced the noise of the CT images, which had different characteristics with training images. Therefore, the DRL model is able to reduce image noise as well as maintain the structural information of CT images.

A Study on the Bonding Strength Analysis according to the Surface Treatment Characteristics of Aluminum Bar-Cowl Cross Member of Composite Material Injection Insert (복합소재 사출인서트 알루미늄 바 카울크로스멤버 표면처리 특성에 따른 접합강도 분석 연구)

  • Son, Dong il;So, Sangwoo;Hwang, Hyuntae;Choi, Dong hyuk;Choi, Wan gyu;Kim, Sun kyung;Kim, Dae il
    • Composites Research
    • /
    • v.33 no.6
    • /
    • pp.360-364
    • /
    • 2020
  • Although research and development of existing steel-made Cowl Cross Member(CCM) was carried out with magnesium and plastic to make vehicles lighter, it is difficult to apply them to performance problems in the vehicle's mounting condition. Recently, the company is conducting research on the injection CCM of the composite insert as a lightweight component that is most suitable for mass-production of automotive parts. This is a manufacturing process that inserts composite injection bracket parts into aluminum bar, and the adhesion of the two parts is one of the important factors considering the vehicle's mounting conditions. In this study, the joint strength of Aluminum bar is one of the important factors as a study for the injection of aluminum bar into PA6-GF60 composite material. For the analysis of these research, the method of spraying adhesive to the aluminum bar and the case of knurling treatment have been analyzed and the bonding strength of the direction of rotation and lateral direction has been analyzed for each part between the aluminum bar of the cowl cross member and the shape of the injection component of composite materials.

Experimental Study on Aerodynamic Performance and Wake Characteristics of the Small Ducted Fan for VTOL UAV (수직 이착륙 무인기용 소형 덕티드팬의 공력성능 및 후류특성에 관한 실험적 연구)

  • Shin, Soo-Hee;Lee, Seung-Hun;Kim, Yang-Won;Cho, Tae-Hwan
    • Journal of the Korean Society for Aeronautical & Space Sciences
    • /
    • v.50 no.1
    • /
    • pp.1-12
    • /
    • 2022
  • Wind tunnel test for a small scale electric ducted fan with a 104mm diameter was conducted to analyze the aerodynamic characteristics when it was used as a propulsion system of tilt-propeller UAV. Experimental conditions were derived from flight conditions of a sub-scaled OPPAV. Forces and moments of the ducted fan model were measured by a 6-axis balance and 3-dimensional wake vectors which could induce an aerodynamic influence in the vehicle were measured by 5-hole probes. Thrust and torque on hover and cruise conditions were measured and analyzed to drive out the operating conditions when it was applied in the sub-scaled OPPAV. On transition conditions, thrust keep its value with tilt angle variation below 40° and increase after that. But, sideforce increase constantly until 75°. The maximum axial velocity in the wake on hover and cruise conditions was around 60m/s and tangential velocity was around 12m/s. The position of the maximum axial velocity and vortex center move off the fan rotation center line as the tilt angle increases.

Development of CanSat System for Collecting Weather Information With Autorotating Science Payload Ejection Function (자동회전 과학 탑재체 사출 기능을 갖춘 기상정보 수집용 캔위성 체계 개발)

  • Kim, Youngjun;Park, Junsoo;Nam, Jaeyoung;Lee, Junhyuck;Choi, Yunwon;Yoo, Seunghoon;Lee, Sanghyun;Lee, Younggun
    • Journal of the Korean Society for Aeronautical & Space Sciences
    • /
    • v.50 no.8
    • /
    • pp.573-581
    • /
    • 2022
  • This paper deals with the development of CanSat system, which ejects two maple seed-type autorotating science payloads and collects weather information. The CanSat consists of two autorotating science payloads and a container. The container is equipped with devices for launching science payloads and communication with the ground station, and launches science payloads one by one at different designated altitudes. The science payload consists of a space for loading and a large wing, and rotates to generate lift for slowing down the fall speed. Specifically, after being ejected, it descends at a speed of 20 m/s or less, measures the rotation rate, atmospheric pressure, and temperature, and transmits the measured value to the container at a rate of once per second. The communication system is a master-slave structure, and the science payload transmits all data to the master container, which aggregates both the received data and its own data, and transmits it to the ground station. All telemetry can be checked in real time using the ground station software developed in-house. A simulation was performed in the simulation environment, and the performance of the CanSat system that satisfies the mission requirements was confirmed.

A Study on Quality Improvement and Verification of Recycled Coarse Aggregate for Concrete Using an Impact Crusher with Radial Rotation (방사형 회전이 추가된 임팩트 크러셔를 이용한 콘크리트용 순환굵은골재 품질향상 및 검증 연구)

  • Jeon, Duk-Woo;Kim, Yong-Seong;Jeon, Chan-Soo;Choi, Won-Young;Cho, Won-Ig
    • Journal of the Korean Recycled Construction Resources Institute
    • /
    • v.10 no.2
    • /
    • pp.133-142
    • /
    • 2022
  • The purpose of this study is to develop an impact crusher with a radial rotating plate installed at the bottom, which is a shock absorber that can produce high-quality recycled coarse aggregate for concrete and to verify the effect of improving the quality performance of recycled coarse aggregate and its applicability through concrete tests. As a result, it showed improved quality in all items such as absolute dry density, absorption rate, abrasion resistance, Particle shape judgment rate, amount lost in the 0.08 mm sieve passing test, alkali aggregate reaction, clay mass, stability, and impurity content, and it was found to meet the criteria of recycled aggregate quality standards. In addition, the air volume and slump of concrete to which recycled coarse aggregate is applied meet all domestic standards. According to the test results of the compressive strength characteristics by age of concrete according to the mixing ratio of the recycled coarse aggregate, it was confirmed that the mixing ratio of the recycled coarse aggregate was applicable up to 60 %.

Training future Korean medicine doctors to perform bee venom acupuncture and obtain informed consent using an objective structured clinical examination (객관 구조화 임상시험을 활용한 봉약침 시술 전 과정에 대한 교육효과)

  • Cho, Eunbyul;Jeon, Hyesoo;Kwon, O Sang;Hong, Jiseong;Lee, Jaehoon;Jung, Eunho;Park, Jiwon;Seo, Wookcheol;Lim, Kyu Sang;Cho, Nam geun
    • The Journal of Korean Medicine
    • /
    • v.43 no.1
    • /
    • pp.6-17
    • /
    • 2022
  • Objectives: This study describes the implementation of a training course that aimed to increase the competency of undergraduate students of Korean medicine at a single college to obtain informed consent and perform bee venom acupuncture using an objective structured clinical examination (OSCE). Methods: We developed and implemented a short training course for 111 fourth-year students of Korean medicine during their clinical rotation at the Department of Acupuncture and Moxibustion Medicine. Lectures were conducted on the effects of and hypersensitivity reactions to bee venom acupuncture, obtaining informed consent, performing skin test and bee venom acupuncture. Due to the COVID-19 pandemic, some students were offered online lectures, and some could not experience the performance of OSCE in person. A survey with 16 closed and three open questions was used to investigate self-efficacy, opinions about the online lectures, and the OSCE. Results: Out of 111 questionnaires, 104 were completed (94%). Students were generally satisfied with the online lectures and OSCE. For the subjective questionnaire about what was helpful in the training of bee venom acupuncture techniques and OSCE, the authenticity of the teaching method was recorded the highest. Conclusions: This study showed that online lectures were effective in teaching clinical skills of Korean Medicine. It is necessary to produce standard educational materials for clinical skills of Korean Medicine, and studies to analyze the reliability and validity of OSCE are needed.