• Title/Summary/Keyword: rotary function

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A Simulation of Forcing Function for the Piping Vibration in Petrochemical Plants (석유화학 플랜트에서 배관 가진 함수의 시뮬레이션에 관한 연구)

  • 민선규;최명진;김경훈
    • Journal of the Korea Society for Simulation
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    • v.10 no.4
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    • pp.1-10
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    • 2001
  • For the simulation of piping vibrations in petrochemical plants, forcing functions mainly depend upon the equipment working mechanism and vibration resources in the piping systems. In general, harmonic function is used to simulate rotary equipment. Mechanical driving frequencies, wave functions, and response spectrum are used to simulate reciprocating compressors, surge vibration of long transfer piping, and seismic/wind vibration, respectively. In this study, the general suggestions for forcing functions were reviewed and proposed the forcing function to simulate the spray injection system inside the pipe in which two different fluids are distributed uniformly. To confirm the results, the scheme was applied for a real piping system. The vibration mode of the real system was consistent with the 4th mode (26.725 Hz) obtained by simulation using the forcing function presented in this study.

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A Comparison of the Effectiveness of Stainless-Steel Hand Instrument and Rotary NiTi Retreatment Instrument to Remove Gutta-Percha in Curved Root Canals (만곡된 근관에서 Gutta-Percha 제거 시 스테인리스스틸 수기구와 회전식 NiTi 재치료용 기구의 효과 비교)

  • Nam, Dong-Goo;Kim, Min-Jeong;Cho, Hye-Jin;Lee, Kwang-Won;Yu, Mi-Kyung
    • Journal of Dental Rehabilitation and Applied Science
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    • v.27 no.1
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    • pp.99-107
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    • 2011
  • The main objective of nonsurgical retreatment is to disinfect the root canal space for periradicular healing. Thus, efficient removal of the filling material from the root canal system is essential to ensure a favorable outcome. Traditionally, the removal of root canal filling material was performed by stainless steel hand instrument and this procedure is time and effort-consuming. Recently, rotary NiTi retreatment instruments are developed to effective removal of root canal filling material. The aim of this study was to evaluate the effectiveness of stainless-steel hand instrument and rotary NiTi retreatment instrument when removing gutta-percha in curved root canals. For the remaining materials, there were no significant differences between groups. But the rotary NiTi system proved to be faster than hand instruments in removing root filling materials.

A Study on Deduction and Characteristic Analysis of Magnetic Equivalent Circuit Parameters of a Rotary-typed Small-scaled LIM for a Railway Transit (철도차량용 선형유도전동기 축소-회전형모델의 자기등가회로 파라미터 도출 및 특성 분석 연구)

  • Park, Chan-Bae;Lee, Hyung-Woo;Lee, Byung-Song
    • Journal of the Korean Society for Railway
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    • v.13 no.4
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    • pp.404-411
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    • 2010
  • Authors conducted a deduction and characteristic calculation of the some parameters using a magnetic equivalent circuit method to verify a basic design result of a rotary-typed small-scaled linear induction motor for a railway transit. In a LIM, it is possible to express the parameters of the magnetic equivalent circuit into a function of the shape of the secondary aluminium plate and the airgap between the LIM primary core and the secondary aluminium plate. It means that the LIM properties can be changed considerably by the shape of the secondary aluminium plate and the airgap between the LIM primary core and the secondary aluminium plate. So, authors analyzed a tendency of changes of the magnetic equivalent circuit parameters and the LIM characteristics by changing of the airgap, the thickness of the secondary aluminium plate and the overhang length and shape of a rotary-typed small-scaled LIM, and accomplished a basic research to develop a real-scaled LIM for a railway transit.

A Characteristics of pressure Propagation According to Frequency Changes in a Hydraulic Pipeline (유압관로의 주파수변화 따른 압력전파특성)

  • 유영태;나기대;김지환
    • Transactions of the Korean Society of Machine Tool Engineers
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    • v.11 no.2
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    • pp.71-79
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    • 2002
  • In this paper, an oil hydraulic pipeline is terminated by both rotary sinusoidal flow generator at upstream oriffice at down stream. The pulsating pressure wave from generated by the rotary sinusoidal flow generator, is measured by using sensor. In the analysis of this paper, a component of the fundamental frequency is obtained by using Laplace transformation.. The experimental and analytical results make clear that (1) viscosity is significant role in hydraulic pipe. (2) When pulsating frequency is matched with the natural frequency, resonance frequency occured periodically. According to the study proposed here, dynamic pressure in a circular oil pipe is expressed in propagation of pressure wave with respect to frequency and Bessel function. The resonance at oil temperature $20^{\circ}$$0^{\circ}C$ in this study. The abrupt change of gain value is due to effect of resonance frequency. The results of experiment are compared with the calculated results, and agreement of both results is fairly good.

An exact transfer matrix method for coupled bending and bending vibrations of a twisted Timoshenko beam

  • Lee, Jung Woo;Lee, Jung Youn
    • Structural Engineering and Mechanics
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    • v.72 no.6
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    • pp.797-807
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    • 2019
  • In this study, an exact transfer matrix expression for a twisted uniform beam considering the effect of shear deformation and rotary inertia is developed. The particular transfer matrix is derived by applying the distributed mass and transcendental function while using a local coordinate system. The results obtained from this method are independent for a number of subdivided elements, and this method can determine the required number of exact solutions for the free vibration characteristics of a twisted uniform Timoshenko beam using a single element. In addition, it can be used as a useful numerical method for the computation of high-order natural frequencies. To validate the accuracy of the proposed method, the computed results are compared with those reported in the existing literature, and the comparison results indicate notably good agreement. In addition, the method is used to investigate the effects of shear deformation and rotary inertia for a twisted beam.

Mathematical Modelling of a Double-sided Linear Induction Motor and Derivation of Equvalent Circuit (양측식 선형 유도 전동기의 수학적 모델링과 등가 회로 유도)

  • Hong, E.P.;Eyou, H.G.;Yoo, J.Y.;Park, G.T.
    • Proceedings of the KIEE Conference
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    • 1995.07a
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    • pp.337-339
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    • 1995
  • A Linear Induction Machine(LIM) is the motor which is developed from an rotary induction machine. Usually, the electromagnetic field of an LIM is analyzed by Maxwell's equations. The structure of an LIM is different from a conventional rotary machine, an LIM has some particular characteristics such as the end effects. Hence, the mathematical analysis of an LIM is very complicated and the implementation of the equivalent model is difficult. In this paper, the dynamic equations and the equivalent model of a Double-sided short primary LIM(DLIM) is obtained by the winding function and a d-q theory. The validity of the proposed methodology is verified by numerical analysis.

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Comparative Study on the Ability of Instruments to Maintain Original Canal Curvature of Continuous rotary System and Single File System (Continuous rotary system과 single file system의 만곡 근관 형태 유지능에 대한 비교 연구)

  • Park, Sang-Hee;Kim, Deok-Joong;Song, Yong-Beom;Lee, Hye-Yun;Kim, Hyoung-Sun;Lee, Kwang-Won;Yu, Mi-Kyung
    • Journal of Dental Rehabilitation and Applied Science
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    • v.28 no.4
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    • pp.371-383
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    • 2012
  • Shaping the root canal system to maintain original canal curvature is essential to clinical success in endodontic treatment. Opposed to most root canals that are curved, endodontic instruments are made from straight metal blanks. They have a tendency of straightening the root canal during preparation and frequently result in procedural errors. A new treatment method to maintain original canal curvature during shaping has been introduced for preventing procedural errors. The aim of this study was to compare the ability of instruments to maintain original canal curvature of continuous rotary system and single file system. Thirty ISO 15, 0.02 taper, Endo Training Blocks(Dentsplay Maillefer) were used. Specimens were assigned to 1 of 3 groups for shaping: specimens in group 1 were shaped with ProFile #20/.06 at the WL. Specimens in group 2 were shaped with Mtwo #35/.04 at the WL. Specimens in group 3 were shaped with WaveOne Primary reciprocating files at the WL after the glide path was achieved with PathFile. Pre- and postinstrumentation digital images were superimposed and processed with Matlab r2010b(The MathWorks Inc, Natick, MA) software to analyze the curvature-radius ratio(CRr), representing canal curvature modification. Data for comparison on the ability of instruments to maintain original canal curvature depending on each Ni-Ti file were analyzed with 1-way ANOVA(P<.05). Data for comparison on the ability of instruments to maintain original canal curvature depending on each Ni-Ti file system were analyzed with independent t-test(P<.05). A statistically significant difference(P<0.05) was noted on each Ni-Ti file. ProFile and WaveOne instrumentations maintained the original canal curvature significantly better(P<0.05) than Mtwo file. There were no significant difference(P>0.05) between continuous rotary system and single file system. Under the conditions of this study, ProFile and WaveOne instruments maintained the original curvature significantly better than Mtwo file and were less modification of the canal curvature compared. There was no significant difference between continuous rotary system and single file system in shaping of simulated canals. As clinical practitioners, it may be advantages to use hybrid approach when root canal shapes depending on the design and usage of Ni-Ti files.

A study on the straight cruise of fish robot according to biological mimic (생물학적 모방에 따른 물고기 로봇의 직진유영 연구)

  • Park, Jin-Hyun;Lee, Tae-Hwan;Choi, Young-Kiu
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.15 no.8
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    • pp.1756-1763
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    • 2011
  • This paper was researched the straight cruise of fish robot according to biological mimic, and it was compared the proposed method which was considered up to 7th order components in fourier series of Liu's tail motion function with the approximate method which was used general sine function by simulation. If fish robot has a large number of links and if the length of tail link is long. The end rotary joint trajectory of tail motion function generally is different from sine function. Therefore The approximate method which expresses tail motion trajectories as fundamental component in fourier series has a problem. Through the computer simulation, the proposed method showed 10% excellent propulsion and velocity than the conventional method.

The Returning Force Analysis of Working Fluid and the Heat Transfer Characteristics in Revolving Heat Pipe Heat Exchanger (회전형 히트파이프 열교환기의 작동유체 귀환력 해석 및 열전달특성에 관한 연구)

  • 이기우;박기호;전원표
    • Journal of Energy Engineering
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    • v.10 no.3
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    • pp.214-222
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    • 2001
  • The purpose of this research it to develop gas-air rotary heat exchanger using heat pipe and the performances were examined by way of the theoretical analysis and the experiment. Centrifugal force to return the working fluid in heat pipe elements with different radius was evaluated as a function of the revolution speed and inclination angle, and a rotary heat exchanger with 60 heat pipes in 3 rows was designed and manufactured. The inclination angle of a heat pipe relative to the revolving axis was designed to be 2$^{\circ}$and water was used as a working fluid. Experimental result showed the heat exchange rate was enhanced by 16% with compared to the calculated value.

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Modeling and Analysis of a Novel Two-Axis Rotary Electromagnetic Actuator for Fast Steering Mirror

  • Long, Yongjun;Wang, Chunlei;Dai, Xin;Wei, Xiaohui;Wang, Shigang
    • Journal of Magnetics
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    • v.19 no.2
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    • pp.130-139
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    • 2014
  • This paper focuses on the modeling and analysis a novel two-axis rotary normal-stress electromagnetic actuator with compact structure for fast steering mirror (FSM). The actuator has high force density similar to a solenoid, but its torque output is nearly a linear function of both its driving current and rotation angle, showing that the actuator is ideal for FSM. In addition, the actuator is designed with a new cross topology armature and no additional axial force is generated when the actuator works. With flux leakage being involved in the actuator modeling properly, an accurate analytical model of the actuator, which shows the actuator's linear characteristics, is obtained via the commonly used equivalent magnetic circuit method. Finally, numerical simulation is presented to validate the analytical actuator model. It is shown that the analytical results are in a good agreement with the simulation results.