• Title, Summary, Keyword: Circular Coil

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Simulation of tracking errors for non-circular cutting using voice coil motor (VCM을 이용한 비원형 형상 가공의 궤적 오차 시뮬레이션)

  • Hwang J.D.;Kwak Y.K.;Kim S.H.;Ahan J.H.
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • pp.57-58
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    • 2006
  • A Simulation model is developed to minimize the path tracking errors when the non-circular cutting is done by a VCM(voice coil motor) driven tool. The relationship between PWM(Pulse Width Modulation) duty ratio and velocity of voice coil motor is theoretically derived from combining the circuit equation for the coils and the motion equation for the magnetic rod of the voice coil motor. The path tracking errors are showed differently according to the rotational speed, the number of segments and the control period in digital control. Given a required accuracy in the non-circular cutting, the optimal values for those parameters are determined based on the developed simulation model.

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Performance Test of a Fan Coil with an Oval-Type Heat Exchanger (타원관 열교환기를 적용한 팬코일 성능 시험)

  • Yoon, Jeadong;Lee, Seunghyun;Sung, Jeayong;Lee, Myeong Ho
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.26 no.2
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    • pp.67-71
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    • 2014
  • In this study, a fan coil unit with an oval-type heat exchanger has been developed. The performance of the present fan coil unit has been investigated, by comparison with the previous fan coil unit with a circular-type heat exchanger. For the fan coil unit with circular- and oval-type heat exchangers, the heat flux and pressure loss through the heat exchangers were measured at standard operating conditions. In addition, the wind speeds exhausted from the fan coil units were compared, for the same fan motor operation. The experimental results show that the average wind speed of the oval-type heat exchanger is 20 percent higher than that of the circular-type heat exchanger. The heat flux in the oval-type heat exchanger is enhanced by 40% or more, over the circular-type heat exchanger.

Mutual Inductance Calculation and Analysis between Two Circular Coils of Perpendicular Arrangement (수직 배열된 원형 코일 사이의 상호 인덕턴스 계산 및 해석)

  • Kim, Jin-Wook;Son, Hyeon-Chang;Kim, Do-Hyeon;Kim, Kwan-Ho;Park, Young-Jin
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.22 no.10
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    • pp.999-1004
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    • 2011
  • In this paper, calculation method of mutual inductance for two circular coils which are widely used in wireless power transfer system and analysis results using the method are proposed. Two circular coils are arranged in a perpendicular way. For calculation of the mutual inductance, an Rx coil placed perpendicularly with the other coil is uniformly subdivided into many unit cells and both magnetic flux density linked with the Rx coil at each unit cell and the total magnetic flux density of the Rx coil are obtained. Two circular coils are considered as a filamentary coil and uniform current density on each coil is assumed. For verification, helical and spiral coils are fabricated. As a result of measurement in 50 cm to 100 cm distance, theoretical mutual inductance is almost agreed with measured one.

Vibration Suppression of Beam Using Magnet and Coil (자석과 코일을 이용한 빔의 진동 억제)

  • Cheng, Tai-Hong;Jung, Jung-Hwan;Oh, Il-Kwon
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.727-730
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    • 2007
  • Coil inductor has been used widely as an electromagnet, because of the high magnetic filed resulting from the voltage applied to the coil. In this study the coils were used in vibration suppression as an actuator. The control system consists of a coil attached in aluminum beam and a permanent magnet set at its bottom. This actuation method is easy to be incorporated into the system and allows significant forces to be applied without contacting with the structure. Three types of coils (cylindrical type, square type, Circular sheet type) were employed in vibration suppression of cantilever beam. The positive position feedback (PPF) controller was applied to the magnet-coil actuator to suppress the first mode of vibration. Experimental results showed that the cylindrical type and square type coil made good vibration suppression efficiency under PPF controller than their eddy current damper. However, there was minimal difference for the circular sheet type coil if compared with its eddy current damper.

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Fabrication of a Circular Coil for the Study on the Magnetic Field Tolerance of TMP

  • Baik, Kyungmin;Cheung, Wan-Sup;Lim, Jong-Yeon
    • Proceedings of the Korean Vacuum Society Conference
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    • pp.153-153
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    • 2013
  • Turbomolecular pump (TMP) is widely used to obtain and maintain high vacuum by spinning turbine rotors to migrate gas molecules to the exhaust of the pump. However, performance of the TMP has not been well observed when it is influenced by strong magnetic field. Such study may give useful information about magnetic field tolerance of TMP, development of magnetic shielding technique for key components of TMP, etc. For this purpose, magnetic field induced by a circular current source was firstly designed and investigated. Using spherical coordinates and vector potential, magnetic field throughout the space including axis of rotation was calculated. Due to the rotational symmetry of the circular current source, induced magnetic field is azimuthally symmetric and, thus, is analyzed by radial and polar components of the magnetic fields. In order to enhance the numerical accuracy for the calculation, magnetic field was expressed by complete elliptic integrals of first and second kinds. According to the calculation, when 1 A of DC-current passes through a 1 turned circular wire with 50 cm of diameter, overall magnitude of the inducedmagnetic field was about 0.02 Gauss, which was used to the determination of the current and the number of turns of wires to fabricate the coil for the study on the magnetic field tolerance of TMP.

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A Study on the Analysis and Improvement of Forming Process of a No-Bridge Blank (No-Bridge Blank의 공정 해석 및 성형 공정 개선에 관한 연구)

  • Lee Y. W.;Cho K. Z.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • pp.85-88
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    • 2001
  • Deep drawing process, one of sheet metal forming methods, is used widely. Circular or square shape blanks are currently studied mainly. Especially, circular blank for coating case of chip condenser remains bridges when it is made out of aluminum coil. The bridge reduces Material-withdrawal-rate of aluminum coil to $60\%$. This paper proposes a no-bridge blank instead of circular blank. To get the different values of two cases, comparison circular blank with no-bridge blank is accomplished in the point of thickness strain in the vicinity of flange. In order to find optimal condition in new proposed blank, several process variables - those are blank holder shape, die shape radii, punch shape radii and blank holding force - are changed.

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A Study on the Drag Reduction Effect and Heat Transfer Enhancement of Non ionized Surfactant and Water Mixture in a Circular Pipe Flow (비이온계 계면활성제 첨가수에 대한 관내 유동저항 감소 및 열전달 촉진에 관한 연구)

  • Kim, Myoung-Jun
    • Journal of the Korean Society of Marine Engineering
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    • v.31 no.5
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    • pp.552-557
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    • 2007
  • This paper has dealt with the effect of non ionized surfactant and water mixture on drag reduction and heat transfer enhancement in a circular pipe flow with experimentally. The test section was consisted of stainless steel pipe with inside diameter of 16mm. The wire coil was used to increase heat transfer in a pipe and the on ionized surfactant(Oleyl Dihydroxyethyl Amino Oxide, ODEAO) was used to reduce the drag force of water mixture with surfactant. The main parameters of this experiment were diameter and pitch of wire coil and the ratio of test section length and horizontal wire coil length. In this experiment, the acquired results were 1) Drag reduction effect existed in this ODEAO-water mixture, 2) Friction factor and heat transfer were increased with insertion the heat transfer enhancement coil, 3) With increasing of pitch ratio, heat transfer was decreased, and 4) Heat transfer was decreased by the decreasing of inserting coil diameter.

The study to flat-type generate of magnetic field with CW (Continue wave) frequency and AM (Amplitude modulation) frequency

  • Shin, Gi Won;Kang, Chang Ho;Lee, Min Jun;Yang, Sung Jae;Lee, Hyuk Ho;Hong, Hyun Bin;Jo, Tae Hoon;Kwon, Gi Chung
    • Proceedings of the Korean Vacuum Society Conference
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    • pp.139.2-139.2
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    • 2015
  • In this study, We applied the magnetic field that has CW frequency and AM frequency to heating magnetic nano powder. For this experiment, We set up the devices flat-type magnetic field generator with CW frequency and AM frequency. We supplied the current to encircling coil by adjusting the power of generating of magnetic field device for AC voltage through Slidacs and using way of LC resonance circuit and SMPS(Switching Mode Power Supply). Above the encircling coil, We covered the circular flat insulator like glass. And we located the well plate containing the magnetic nano powder liquor above the circular flat insulator and exposed the magnetic field to this well plate. Using the flat-type magnetic field generator with CW and AM frequency and the magnetic field measurement sensor(Magnetic pick up coil or Hall sensor), We measured the strength of the magnetic field of circular flat insulator's surface in each position. The temperature of the magnetic nano powder in the well plate was quantitatively measured by the magnetic field strength through the Fluoroptic thermometer.

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Purification and Structural Studies on Human Pro-ghrelin

  • Yun, Ji-Hye;Lee, Jee-Won;Lee, Weon-Tae
    • Journal of the Korean Magnetic Resonance Society
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    • v.12 no.1
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    • pp.40-50
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    • 2008
  • Ghrelin is a unique peptide hormone that releases growth factor and it stimulates appetite. It comes from pre pro-ghrelin by the post translational modification process and its innate functions are known as food up-take and the growth hormone regulation. Therefore, the structural information of ghrelin precursor is of importance in understanding it function. From our results, we found that the solution structure of ghrelin is mostly random coil conformation at neutral pH value and the structural population changes with pH environments. Data from circular dichroism in different TFE concentrations revealed that the secondary structure changes from random coil to a-helix and the isodichroic point is observed at 202nm, implying that two equilibrium states exist between random coil and helical structure.

Mutual Inductance of the Non-Coaxial Coils in Coil Gun

  • Kim, Ki-Bong
    • Proceedings of the KIEE Conference
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    • pp.120-123
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    • 1994
  • The purpose of this paper is to describe the mutual inductance between two non-coaxial circular coils in coil gun. As being in many electromagnetic applications, one of them is fixed and the other one is moving and, being not supported, its axis may not coincide with the axis of the fixed coil. This paper presents a method for the calculation of the mutual inductance in case of non-coaxial coupled coils, the characteristics of this inductance and experimental results. For the computation, the complete elliptic integrals formula and mesh matrix technique were introduced. This method enables accurate results from relatively simple procedure and calculation program.

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