• Title/Summary/Keyword: twisted wave

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A Parametric Study on the Characteristics of the Oil-Lubricated Wave Journal Bearing

  • Suh, Hyun-Seung;Rhim, Yoon-Chul
    • KSTLE International Journal
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    • v.2 no.1
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    • pp.59-64
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    • 2001
  • A new bearing concept, the wave journal bearing, has been developed to improve the static and dynamic performance of a hydrodynamic journal bearing. This concept features a wave in bearing surface. Not only straight but also twisted wave journal bearings are investigated numerically. The performances of straight and twisted bearings are compared to a plain journal bearing over a wide range of eccentricity. The bearing load and stability characteristics are dependent on the geometric parameters such as the number of waves, the amplitude and the starting point of the wave relative to the applied load direction. The bearing performance is analyzed for various configurations and for both cases of smooth and wave member notation. The wave journal bearing, especially for the twisted one, offers better stability than the plain journal bearing under all eccentricity ratios and load orientation.

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A Parametric Study on the Characteristics of the Oil-Lubricated Wave Journal Bearing (오일윤활 웨이브 저어널 베어링의 특성해석)

  • 서현승;임윤철
    • Tribology and Lubricants
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    • v.14 no.4
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    • pp.100-107
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    • 1998
  • A new bearing concept, the wave journal bearing, has been developed to improve the static and dynamic performance of a hydrodynamic journal bearing. This concept features a wave in bearing surface. Not only straight but also twisted wave journal bearing are investigated numerically. The performances of straight and twisted bearings are compared to a plain journal bearing over a wide range of eccentricity. The bearing load and stability characteristics are dependent on the geometric parameters such as the number of waves, the amplitude and the start point of the wave relative to the applied load direction. The wave journal bearing, especially for the twisted one, offers better stability than the plain journal bearing under all eccentricity and load orientation.

An Analysis of Wave Journal Bearing (웨이브 저어널 베어링의 특성해석)

  • 서현승;임윤철
    • Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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    • 1998.04a
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    • pp.190-197
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    • 1998
  • A new bearing concept, the wave journal bearing, has been developed to improve the steady and dynamic performance of a hydrodynamic journal bearing. This concept features a wave in inner bearing surface. Not only straight but also twisted wave journal bearing are investigated numerically. The performances of straight and twisted bearings are compared to a plain journal bearing over a relatively wide range of eccentricity. The bearing load and stability characteristics are dependent on the geometric parameters such as the number of waves, the amplitude and the starting point of the wave relative to the applied load. The wave journal bearing, especially for the twisted one, offers better stability than the plain journal bearing under all eccentricity and all wave to load orientation.

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A numerical and experimental study on the performance of a twisted rudder with wavy configuration

  • Shin, Yong Jin;Kim, Moon Chan;Lee, Joon-Hyoung;Song, Mu Seok
    • International Journal of Naval Architecture and Ocean Engineering
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    • v.11 no.1
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    • pp.131-142
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    • 2019
  • In this paper, a Wavy Twisted Rudder (WTR) is proposed to address the discontinuity of the twisted section and increase the stalling angle in comparison to a conventional full-spade Twisted Rudder (TR). The wave configuration was applied to a KRISO Container Ship (KCS) to confirm the characteristics of the rudder under the influence of the propeller wake. The resistance, self-propulsion performance, and rudder force at high angles of the wavy twisted rudder and twisted rudder were compared using Computational Fluid Dynamics (CFD). The numerical results were compared with the experimental results. The WTR differed from the TR in the degree of separation flow at large rudder angles. This was verified by visualizing the streamline around the rudder. The results confirmed the superiority of the WTR in terms of its delayed stall and high lift-drag ratio.

Polarimetric Measurement of Jones Matrix of a Twisted Nematic Liquid Crystal Spatial Light Modulator

  • Khos-Ochir, Tsogvoo;Munkhbaatar, Purevdorj;Yang, Byung Kwan;Kim, Hyun Woo;Kim, Jin Seung;Kim, Myung-Whun
    • Journal of the Optical Society of Korea
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    • v.16 no.4
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    • pp.443-448
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    • 2012
  • A polarimetric experimental method was developed to determine the Jones matrix elements of transparent optical materials without sign ambiguity. A set of polarization dependent transmittance data of the samples was measured with polarizer - sample - analyzer system and another set of data was measured with polarizer - sample - quarter-wave plate - analyzer. Two data sets were compared and mathematically analyzed to obtain the correct signs of the elements of the matrix. The Jones matrix elements of a quarter-wave plate were determined to check the validity of the method. The experimentally obtained matrix elements of the quarter-wave plate were consistent with the theoretical expectations. The same method was applied to obtain the Jones matrix elements of a twisted nematic liquid crystal panel.

Analysis of Shielded Twisted Pair Cable to External Field Coupling by Expanded Chain Matrix Modeling

  • Cho, Yong-Sun;Jung, Hyun-Kyo;Cheon, Changyul;Chung, Young-Seek
    • Journal of Electrical Engineering and Technology
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    • v.9 no.6
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    • pp.2049-2057
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    • 2014
  • In this paper, a numerical method for analyzing coupling between high-altitude electromagnetic pulse (HEMP) as external field and a shielded twisted pair (STP) cable is proposed, which is based on an expanded chain matrix. Load responses of electromagnetic (EM) field excitation in uniform transmission line (TL) are solved by Baum-Liu-Tesche (BLT) equations in frequency domain, however, it is difficult to apply BLT equations to solve load responses of STP cable because the iteratively changing configuration of each twisted pairs are involved in cable. To avoid this problem and decrease memory and CPU time, we proposed the expanded chain matrix modeling method that is calculated using ABCD parameters, and applied multi-conductor transmission line (MTL) theory to consider the EMP coupling effectiveness of each twisted pairs. The results implemented by the proposed method are presented and compared with those obtained by the finite-difference time domain (FDTD) method as a kind of 3D full wave analysis.

A Solar Cyclone with Chromospheric Running Wave

  • Magara, Tetsuya;An, Jun-Mo;Lee, Hwanhee;Kang, Jihye;Inoue, Satoshi;Choe, Gwang-Son
    • The Bulletin of The Korean Astronomical Society
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    • v.37 no.2
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    • pp.113.2-113.2
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    • 2012
  • An innovative solar observing satellite, Hinode, has successfully observed the detailed evolution of a rapidly developing emerging flux region from the beginning of its appearance at the solar surface. The high spatial and temporal resolution provided by the satellite enables to capture the prominent dynamic processes such as the rotational motion of a polarity region with intense magnetic flux which is reminiscent of a cyclone on the Earth, and a running wave that spreads ahead of this rotating polarity region. This 'solar cyclone' is, on the other hand, generated differently from terrestrial cyclones, and a possible generating mechanism for it is demonstrated with a three-dimensional magnetohydrodynamic simulation of a twisted magnetic flux tube emerging from the solar interior into the solar atmosphere. The simulation shows that the rotational motion is caused by a strong downflow of plasma along the twisted field lines that form a helical pillar standing upright on the Sun.

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An Optical Configuration for the Normally Black Twisted Nematic Liquid Crystal Cell (꼬인 네마틱 액정 셀의 Normally Black 모드 광학설계)

  • Kim, Ki-Han;Baek, Jong-In;Kim, Jae-Chang;Yoon, Tae-Hoon
    • Korean Journal of Optics and Photonics
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    • v.19 no.1
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    • pp.48-53
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    • 2008
  • We propose an optical configuration to compensate dispersion characteristics in the dark state of normally black twisted nematic (NB-TN) liquid crystal display (LCD). We employed a half-wave plate (HWP) and a +A plate to achieve the superior dark state. By using the parameter space diagram (PSD) method, we could obtain the optimum values of parameters and the high contrast-ratio over 500 : 1 could be obtained. Furthermore, excellent dispersion characteristics were also obtained in the bright state. We could confirm the performance of the proposed structure using both the numerical calculations and the experiments.

Study on Housed at Museum of Sun Am Temple (선암사 소장 <용문자수탁의(龍紋刺繡卓衣)> 연구)

  • Sim, Yeon-Ok
    • Journal of the Korean Society of Costume
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    • v.67 no.2
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    • pp.88-100
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    • 2017
  • This study is for the textiles of at Sun Am Temple and characteristic of embroidery. Tak Ui was composed of orange body and green upper cover, and had no strings. The body plate was covered with embroidery, with Gauze base, and upper part was appliqued, by cutting dragon pattern, cloud pattern on satin damask. The thread for embroidery was silk floss, silk twisted thread, rapped gold thread, and rapped silk thread. For padding, it was used cotton thread in the part of dragon's scales. It was used satin stitch, outline stitch, split stitch, couching, and counted stitch, etc. as method of embroidery. In particular, it embroidered counted stitch of diamond shape consecutively on the whole of Tak Ui, it does so with counted stitch of same effect of weaving Brocade in the part of cloud. Besides, it is one of the characteristic for couching rapped silk thread. Such lead embroidery is the popular method in the Ming dynasty of China, in the 16~17 century. The design of Tak Ui is dragon, cloud, and wave in the theme. In the center, 'Seong-su-man-nyeon' was placed on the heads of dragon. This is similar to Dragon Robe of Four-petalled medallion patterns, period of Ming dynasty in China. Therefore, it confirmed that Tak Ui was remodeled the embroidered textiles, made for royal robe, originally, with Tak Ui at temple.

Comparative Study on Mechanical Properties of Sonicated Bamboo and Kenaf Fiber Composite (초음파 처리된 대나무섬유와 케냐프섬유 복합재의 기계적 특성 비교 연구)

  • Lee, Su Kyoung;Park, Eun Young;Park, Tae Sung;An, Seung Kook
    • Textile Coloration and Finishing
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    • v.32 no.4
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    • pp.274-280
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    • 2020
  • This study compared the mechanical properties of bamboo fiber composites and kenaf fiber composites through physical treatment (ultrasonic treatment). Kenaf, a composite of PP reinforced with bamboo fiber, was made using injection molding technology. PP was used as a binder and the ultrasonic treatment time of bamboo and kenaf was increased by 30 minutes to compare and study various mechanical properties of bamboo and kenaf composites through physical treatment. Interfacial properties such as internal cracks and internal structure of the wave cross section were confirmed using a scanning electron microscope (SEM). As a result of the ultrasonic treatment, most of the characteristics were fragile as the ultrasonic treatment time was increased, and it was confirmed that the natural characteristics of the twisted fibers had a great influence on the characteristics of the composite material.