• Title, Summary, Keyword: spiral

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A Study on a Spiral Charge for Charge Simulation Method (전하 중첩법용 Spiral 전하에 관한 검토)

  • 민석원;박은서;송기현
    • Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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    • pp.179-182
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    • 2000
  • This paper investigates characteristics of spiral charge for charge simulation method to calculate electric fields of spiral conductor bundles with spiral rods in 765 kV transmission line. We finds the simulating spiral charge as constant charge density give less potential calculation error than sinusoidal charge density. When a spiral rod is simulated as spiral charge, we also knows two spiral charge can simulate spiral rod best.

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Evaluation of Course-keeping Quality of a Ship by Zig-Zag Test (Zig-Zag test에 의한 선박의 보침성능 평가에 관한 연구)

  • Seung-Keon Lee;Seung-Jae Lee
    • Journal of the Society of Naval Architects of Korea
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    • v.35 no.1
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    • pp.54-60
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    • 1998
  • Generally, spiral test has been used for evaluating course-keeping quality of a ship. But, there are many difficult problems in performing spiral test and reversed spiral test. Therefore, we propose zig-zag test instead of spiral test for evaluating curse-keeping quality of a ship. In this paper, K-T maneuvering response model is applied to the spiral curves which are systematically produced to calculate Zig-zag maneuver. Then, 1st overshoot angle and 2nd overshoot angle are plotted. And the relations between overshoot angles and band widths of spiral curve are discussed.

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A Study on A Spiral Charge for 3 Dimensional Charge Simulation Method (3차원 전하 중첩법용 나선 전하의 특성에 관한 연구)

  • 민석원;박은서;송기현
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.15 no.4
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    • pp.31-36
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    • 2001
  • This paper investigates characteristics of spiral charge for 3 dimensional charge simulation method to calculate electric fields of special conductor bundles with spiral rods in 765kV transmission line. We finds the simulating spiral charge as constant charge density give less potential calculation error than sinusoidal charge falsity. When a spiral rod is simulated as spiral charge, we also knows two spiral charge can simulate spiral rod best.

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The Effect of Annular Slit on a Compressible Spiral Jet Flow (스파이럴 제트 유동에 미치는 환형 슬릿의 영향에 관한 연구)

  • Cho, Wee-Bun;Baek, Seung-Cheul;Kim, Heuy-Dong
    • Proceedings of the KSME Conference
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    • pp.2029-2034
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    • 2004
  • Spiral jet is characterized by a wide region of the free vortex flow with a steep axial velocity gradient, while swirl jet is largely governed by the forced vortex flow and has a very low axial velocity at the jet axis. However, detailed generation mechanism of spiral flow components is not well understood, although the spiral jet is extensively applied in a variety of industrial field. In general, it is known that spiral jet is generated by the radial flow injection through an annular slit which is installed at the inlet of a conical convergent nozzle. The present study describes a computational work to investigate the effects of annular slit on the spiral jet. In the present computation, a finite volume scheme is used to solve three dimensional Naver-Stokes equations with RNG ${\kappa}-{\varepsilon}$ turbulent model. The annular slit width and the pressure ratio of the spiral jet are varied to obtain different spiral flows inside the conical convergent nozzle. The present computational results are compared with the previous experimental data. The results obtained obviously show that the annular slit width and the pressure ratio of the spiral jet strongly influence the characteristics of the spiral jets, such as tangential and axial velocities.

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Spiral motion of the oblate rising bubble (자유 상승하는 편구형 기포의 나선운동)

  • Lee, Jae-Young;Lee, Cheol-Ha
    • Proceedings of the KSME Conference
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    • pp.3015-3020
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    • 2007
  • An experimental study of the dynamic characteristics of the free rising oblate spherical bubble is investigated. As noted by Saffman, the characteristics of the spiral motion are defined with parameters of the spiral frequency, spiral radius, and rising velocity. High speed camera recorded every detail information of free rising bubble. The spiral number, the bubble rise velocity, and the angular velocities were measured for the bubble size between 1.0mm to 20.0mm in diameter. In order to make clear trajectory, we employed the Fast Fourier Transformation for the normal digital camera data to synchronize with the high speed camera data. It was found that the spiral number suggested here was monotonically decreased as the bubble size increases. The present observation, however tells us that previous Saffman's formulation shows a good agreement with the trend, but over estimated spiral number. Therefore, it is recommended that Saffman's theoretical study is needed to be improved.

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Effect of spiral reinforcement ratio and center-hole size of cylinder of concrete (콘크리트 원주공시체에서 나선철근량과 중공크기에 관한 연구)

  • 김민수;김진근;유영섭
    • Proceedings of the Korea Concrete Institute Conference
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    • pp.101-106
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    • 2001
  • This paper presents experimental results for the confining characteristics of cylinder with center-hole and spiral reinforcements. The experiments have been conducted for the specimens with primary variables i.e., spiral reinforcement ratio and diameter of center-hole which affect the compressive strength and stress-strain relationship. Through this research, it was found that the compressive strength and ductility were increased with the ratio of spiral reinforcement because the lateral expansion of the concrete inside the spiral was restrained by the spiral, but dependent on the size of center-hole.

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The Effects of Spiral Taping Treatment on Temporomandibular Disorder (악관절장애(顎關節障碍)의 개구장애(開口障碍)와 통증(痛症)에 대한 첩대요법(貼帶療法)의 효과(效果))

  • Choi, Bo-Hee;Hwang, Jae-Ok;Seo, Jung-Chul
    • Journal of Pharmacopuncture
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    • v.9 no.1
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    • pp.69-73
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    • 2006
  • Objective : The purpose of this study is to estimate the effects of spiral taping treatment on temporomandibular disorder. Methods : 22 temporomandibular disorder patients were treated with spiral taping, and no other treatments such as herbal medicine, acupuncture, herbal acupuncture, and chiropractic therapy were added. We evaluated the improvement by temporomandibular pain and mouth opening range. Results : 11 patients felt no pain or inconvenience of daily life and 4 patients showed improvement of pain or symptom after 1 month of spiral taping theraphy. 3 patients had normal opening size of mouth and convenience of daily life, and 2 patient showed improvement of opening size of mouth as 35mm-40mm after 1 month of spiral taping theraphy. Conclusion : These results suggest spiral taping treatments contribute to the improvement of temporomandibular disorders. Further study is needed for the confirmation of this effect of spiral taping treatments on temporomandibular disorders.

Reconstruction Algorithms for Spiral-scan Echo Planar Imaging (Spiral scan 초고속 자기공명영상 재구성 알고리즘)

  • Ahn, C.B.;Kim, C.Y.;Park, D.J.;Kim, H.J.;Ryu, Y.S.;Yi, Y.;Oh, C.H.;Lee, H.K.
    • Proceedings of the KOSOMBE Conference
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    • v.1996 no.11
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    • pp.157-160
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    • 1996
  • In this paper, reconstruction algorithms of spiral scan imaging which has been used for ultra fast magnetic resonance imaging have been reviewed, and some simulation results using two different algorithms are reported. Since the trajectory of the spiral scan in k-space is the spiral, reconstruction of the spiral scan is not as straight forward as that used in Fourier imaging technique where the sampling points are usually on the rectangular grids. Originally the reconstruction of the spiral scan imaging was based on the convolution backprojection algorithm modified with a shift term, however, some other reconstruction techniques have also been tried by remapping sampling points from spiral trajectory to Cartesian grids. Some experimental aspects of MR spiral scan imaging will also be addressed.

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Spiral Waves and Shocks in Discs around Black Holes: Low Compressibility and High Compressibility Models

  • LANZAFAME GIUSEPPE;BELVEDERE GAETANO
    • Journal of The Korean Astronomical Society
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    • v.34 no.4
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    • pp.313-315
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    • 2001
  • Some authors have concluded that spiral structures and shocks do not develop if an adiabatic index $\gamma$ > 1.16 is adopted in accretion disc modelling, whilst others have claimed that they obtained well defined spirals and shocks adopting a $\gamma$ = 1.2 and a $M_2/ M_1$ = 1 stellar mass ratio. In our opinion, it should be possible to develop spiral structures for low compressibility gas accretion discs if the primary component is a black hole. We considered a primary black hole of 8M0 and a small secondary component of 0.5M$\bigodot$ to favour spiral structures formations and possible spiral shocks via gas compression due to a strong gravitational attraction. We performed two 3D SPH simulations and two 2D SPH simulations and characterized a low compressibility model and a high compressibility model for each couple of simulations. 2D models reveal spiral structures existence. Moreover, spiral shocks are also evident in high compressibility 2D model at the outer disc edge. We believe that we could develop even well defined spiral shocks considering a more massive primary component.

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Effects of Spiral Taping in Motor Disturbance of the Neck Induced by Cervical Sprain -Randomized Clinical Controlled Trials-

  • Kwon, Ki-Rok
    • Journal of Acupuncture Research
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    • v.23 no.2
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    • pp.159-164
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    • 2006
  • Objectives : This study was conducted for objective verification of effects of spiral taping therapy for the patients with motor disturbance. Methods : To verify whether spiral taping therapy is effective for treating motor disturbance from cervical sprain, 28 patients were randomly allocated into the control and experiment groups. Then 23 subjects who fulfilled the experiment requirements were measured for lateral rotation angle using the goniometer. Changes in rotation were observed and compared. Control group received acupuncture and herbal acupuncture treatment, whileas the experiment group received spiral taping therapy in addition. Results : Differences in age and the degree of motor disturbance were disregarded in comparison of the groups prior to rendering treatments. For the control group, significant changes were observed after the second treatment until the termination of treatment. For the experiment group, significant changes were observed after the first treatment until the termination of treatment. Difference between the groups was insignificant but experiment group with spiral taping therapy showed better results. Conclusion : Spiral taping therapy can be an effective complementary treatment method for treating neck motor disturbance. Further studies in the subject should be conducted to yield more concrete verification.

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