• Title, Summary, Keyword: ray tracking

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Analysis of Sun Tracking Error Caused by the Heliostat Driving Axis Geometrical Error Utilizing the Solar Ray Tracing Technique (태양광선 제적추적기법을 이용한 Heliostat 구동축 기구오차에서 기인하는 태양추적오차의 분석)

  • Park, Young-Chil
    • Journal of the Korean Solar Energy Society
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    • v.29 no.2
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    • pp.39-46
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    • 2009
  • Heliostat, as a mirror system tracking the sun's movement, is the most important subsystem determining the efficiency of solar thermal power plant. Thus the accurate sun tracking performance under the various hazardous operating condition, is required. This study presents a methodology of development of the solar ray tracing technique and the application of it in the analysis of sun tracking error due to the heliostat geometrical errors. The geometrical errors considered here are the azimuth axis tilting error and the elevation axis tilting error. We first analyze the geometry of solar ray reflected from the heliostat. Then the point on the receiver, where the solar ray reflected from the heliostat is landed, is computed and compared with the original intended point, which represents the sun tracking error. The result obtained shows that the effect of geometrical error on the sun tracking performance is varying with time(season) and the heliostat location. It also shows that the heliostat located near the solar tower has larger sun tracking error than that of the heliostat located farther.

A Study on the Ultraviolet Aging characteristics of Outdoor Polymeric Insulating Materials (옥외용 고분자 절연재료의 자외선 열화특성 연구)

  • Kim, Y.S.;Lee, S.J.;Park, W.K.;Jeong, S.W.
    • Proceedings of the KIEE Conference
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    • pp.1404-1406
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    • 1998
  • The outdoor polymeric insulating materials such as silicone rubber, ethylene propylene diene monomer(EPDM), ethylene vinyl acetate(EVA) and epoxy are aged by various natural environment with the long-term performance in outdoor. In this paper, the effects of UV-ray on surface of silicone rubber were investigated by using the weather-Ometer. The accelerated aging stresses were simulated by UV radiation. high temperature and humidity as well as water spray. These the aging characteristics were examined through contact angle measurements, tracking resistance test, FT-IR and SEM/EDS analysis. the experimental results showed that tracking resistance decreases with increase in the UV-ray irradiation period. But the surface of silicone rubber kept hydrophobicity. It is found that the inorganic filler such as $Al(OH)_3$ improves tracking resistance and the $TiO_2$ is very effective in preventing degradation of silicone rubber surface from UV-ray.

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Tracking performance of a CDD-DLL code tracking loop in a multipath fading channel (다중경로 페이딩 전송로에서 CDD-DLL 부호 추적 루프의 추적성능)

  • 김진영;이재홍
    • Journal of the Korean Institute of Telematics and Electronics A
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    • v.33A no.3
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    • pp.1-9
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    • 1996
  • in this paper, we analyzed CDD-DLL code tracking loop for tracking of direct-sequence spread-spectrum signals in a multipath fading channel. The multipath fading channel is modeled as two-ray rayleigh fading channel which is well applicable in a land mobile communication environments. We use trackin jitter variance and mean-time-to-lose-lick as performance measures. From the numerical resutls, it is shown that the effect of multipath fading decreases as SNR/bit increases. Also it is shown that CDD-DLL provides superior jitter performance compared with noncoherent DLL and jitter performance improvement is more significant for a two-ray rayleigh fading channel than an AWGN channel.

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Acoustic theory application in ultra short baseline system for tracking AUV

  • Ji, Daxiong;Liu, Jian;Zheng, Rong
    • Ocean Systems Engineering
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    • v.3 no.1
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    • pp.71-77
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    • 2013
  • The effective tracking area of ultra short baseline (USBL) systems strongly relates to the safety of autonomous underwater vehicles (AUVs). This problem has not been studied previously. A method for determining the effective tracking area using acoustic theory is proposed. Ray acoustic equations are used to draw rays which ascertain the effective space. The sonar equation is established in order to discover the available range of the USBL system and the background noise level using sonar characteristics. The available range defines a hemisphere like enclosure. The overlap of the effective space with the hemisphere is the effective area for USBL systems tracking AUVs. Lake and sea trials show the proposed method's validity.

Effect of Imperfect Power Control on Performance of a PN Code Tracking Loop for a DS/CDMA System

  • Kim, Jin-Young
    • Proceedings of the IEEK Conference
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    • pp.209-212
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    • 2000
  • In this paper, effect of imperfect power control on performance of a pseudonoise (PN) code tracking loop is analyzed and simulated for a direct-sequence/code-division multiple access (DS/CDMA) system. The multipath fading channel is modeled as a two-ray Rayleigh fading model. Power control error is modeled as a log-normally distributed random variable. The tracking performance of DLL (delay-locked-loop) is evaluated in terms of tracking jitter and mean-time-to-lose-lock (MTLL). From the simulation results, it is shown that the PN tracking performance is very sensitive to the power control error.

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Fast Ray Reordering and Approximate Sibson Interpolation for Foveated Rendering on GPU

  • Kwon, Oh-Seok;park, Keon-kuk;Yoon, Joseph;Kim, Young-Bong
    • Journal of Korea Multimedia Society
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    • v.22 no.2
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    • pp.311-321
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    • 2019
  • Virtual reality applications in Head-Mounted Displays require high frame rates and low latency rendering techniques. Ray tracing offers many benefits, such as high-quality image generation, but has not been utilized due to lower performance than rasterization. But that can obtain good result combined with gaze-tracking technology and human visual system's operation principle. In this paper, we propose a method to optimize the foveated sampling map and to maintain the visual quality through the fast voronoi nearest interpolation. The proposed method further reduces the computational cost that has been improved by the previous foveated sampling. It also smoothes the voronoi boundary using adaptive sibson interpolation, which was not possible in real-time. As a result, the proposed method can render real-time high-quality images with low visual difference.

Evaluation of Photoneutron During Radiation Therapy when Using Flattening Filter and Tracking Jaw with High Energy X-ray (고 에너지 X선 방사선치료 시 Flattening Filter와 Tracking Jaw 사용에 따른 광중성자 발생 평가)

  • Park, Euntae;Jin, Seongjin;Park, Cheolwoo
    • Journal of the Korean Society of Radiology
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    • v.10 no.2
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    • pp.125-131
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    • 2016
  • Radiation therapy is usually using linear accelerator and used X-ray energy is also getting higher. Recently linear accelerators has been developed 3F mode and tracking jaw technology and that was applied for patient therapy. This study aims at measuring photoneutrons depending on the use of 3F and tracking jaw system when radiation is irradiated using a linear accelerator. The generation of photoneutrons of 3F system was 70% smaller than 2F system and that of tracking jaw system was 83% higher than static jaw system. Photoneutron value is relatively low. However, it must be minimized for Photoneutron exposure during radiation therapy.

Robotic Guidance of Distal Screwing for Intramedullary Nailing Using Optical Tracking System (광학식측정장치를 이용한 금속정 내고정 수술의 원위부 나사체결을 위한 로보틱 유도 시스템)

  • An, Liming;Kim, Woo Young;Ko, Seong Young
    • The Journal of Korea Robotics Society
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    • v.12 no.4
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    • pp.411-418
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    • 2017
  • During the intramedullary nailing procedure, surgeons feel difficulty in manipulation of the X-ray device to align it to axes of nailing holes and suffer from the large radiation exposure from the X-ray device. These problems are caused by the fact the surgeon cannot see the hole's location directly and should use the X-ray device to find the hole's location and direction. In this paper, we proposed the robotic guidance of the distal screwing using an optical tracking system. To track the location of the hole for the distal screwing, the reference marker is attached to the proximal end of an intramedullary nail. To guide the drill's direction robustly, the 6-degree-of-freedom robotic arm is used. The robotic arm is controlled so as to align the drill guiding tool attached the robotic arm with the obtained the hole's location. For the safety, the robot's linear and angular velocities are restricted to the predefined values. The experimental results using the artificial bones showed that the position error and the orientation error were 0.91 mm and $1.64^{\circ}$, respectively. The proposed method is simple and easy to implement, thus it is expected to be adopted easily while reducing the radiation exposure significantly.

A Study on the Ultraviolet Aging Characteristics of Outdoor Polymeric Insulating Materials (옥외용 고분자 절연재료의 자외선 열화특성 연구)

  • Kim, Yeong-Seong;Jeong, Sun-Ok
    • Korean Journal of Materials Research
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    • v.9 no.4
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    • pp.409-413
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    • 1999
  • Recently, the polymeric insulators have been accepted in several countries for the outdoor high voltage applications. In comparison with the conventional porcelain, polymeric insulators offer various advantages such as light weight, superior vandal resistance and better contamination performance. The outdoor polymeric insulating materials such as silicone rubber, ethylene propylene diene monomer(EPDM), ethylene vinyl acetate(EVA) and epoxy are aged such as silicone rubber, ethylene propylene diene monomer(EPDM), ethylene vinyl acetate(EVA) and epoxy are aged under the various natural environment with the long-term performance in outdoor. In this paper, the effects of UV-under the various natural environment with the long-term performance in outdoor. In this paper, the effects of UV-ray on the surface of silicone rubber were investigated by using the weather-Ometer. The accelerated aging stresses were simulated by UV radiation, high temperature and humidity as well as water spray. These aging characteristics were examined through contact angle measurements, tracking resistance test, FT-IR and SEM/EDS analysis. The experimental results showed that tracking resistance decreases with increase in the UV-ray irradiation period. But the surface of silicone rubber kept hydrophobicity. It is found that the inorganic filler such as)$ Al(OH_3$ improves tracking resistance and the $Tio_2$is very effective in preventing degradation of silicone rubber surface from UV-ray.

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Robust and Non-fragile $H^{\infty}$ Controller Design for Tracking Servo of Blu-ray disc Drive System (Blu-ray 디스크 드라이브 시스템 트래킹 서보시스템에 대한 견실비약성 $H^{\infty}$ 상태궤환 제어기 설계)

  • Lee, Hyung-Ho;Kim, Joon-Ki;Kim, Woon-Ki;Jo, Sang-Woo;Park, Hong-Bae
    • Journal of the Institute of Electronics Engineers of Korea SC
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    • v.45 no.3
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    • pp.32-41
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    • 2008
  • In this paper, we describe the synthesis of robust and non-fragile $H^{\infty}$ state feedback controllers for linear systems with affine parameter uncertain tracking servo system of blu-ray disc drive, as well as static state feedback controller with polytopic uncertainty Similarity any other control system, the objective of the track-following system design for optical disc drives is to construct the system with better performance and robustness against modeling uncertainties and various disturbances. Also, the obtained condition can be rewritten as parameterized linear matrix inequalities(PLMIs), that is, LMIs whose coefficients are functions of a parameter confined to a compact set. We show that the resulting controller guarantees the asymptotic stability and disturbance attenuation of the closed loop system in spite of controller gain variations within a resulted polytopic region.