• Title/Summary/Keyword: gears

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Retention probability of trawl codend for silver croaker (Argyrosomus argentatus) (트롤 끝자루에 대한 보구치(Argyrosomus argentatus)의 망목 선택성)

  • KIM, Pyungkwan;PARK, Chang-Doo;LEE, Chun-Woo;KIM, Hyung-seok
    • Journal of the Korean Society of Fisheries and Ocean Technology
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    • v.55 no.1
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    • pp.1-6
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    • 2019
  • The annual production of silver croaker (Argyrosomus argentatus) in Korean towed fishing gears has been increased in recent five years. In 2017, the annual production of silver croaker in metric ton was increased 99.2% compared to 2013. However, the research for silver croaker has been focused on ecology in Korea. There has not been enough research in terms of fishing gears. Therefore, the research for retention probability for towed gears was conducted on covered codend method from June, 2016 to July, 2018. During the experiments, the total catch of silver croaker was 1,563. The geometry of the experimental trawl gear was controlled by trawl monitoring system; net height was 3.3 m, distance of trawldoors was 59.8 m and distance of wing net was 17.3 m. The selection curve for silver croaker was estimated by a logit model. The analysis was applied with the confidence interval to reduce uncertainty of the estimation. The $l_{50}$ was 13.87 cm and its selection range was 2.71 cm. P-value was estimated at 0.99. The mesh size for silver croaker in towed gears needs to be adjusted by considering its minimum maturity length, stakeholder's interests and fisheries regulations.

A Study on the Effect of Macro-geometry and Gear Quality on Gear Transmission Error (기어 제원 및 기어 가공정밀도가 기어 전달오차에 미치는 영향에 대한 연구)

  • Lee, Ju-Yeon;Moon, Sang-Gon;Moon, Seok-Pyo;Kim, Su-Chul
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.20 no.11
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    • pp.36-42
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    • 2021
  • This study was conducted to analyze the effect of the gear specification and gear quality corresponding to the macro geometry on the gear transmission error. The two pairs of gears with large and small transmission errors were selected for calculation, and two pairs of gears were manufactured with different gear quality. The test gears were manufactured by two different gear specifications with ISO 5 and 8 gear quality, respectively. The transmission error measurement system consists of an input motor, reducer, encoders, gearbox, torque meter, and powder brake. To confirm the repeatability of the test results, repeatability was confirmed by performing three repetitions under all conditions, and the average value was used to compare the transmission error results. The transmission errors of the gears were analyzed and compared with the test results. When the gear quality was high, the transmission error was generally low depending on the load, and the load at which the decreasing transmission error phenomenon was completed was also lower. Even when the design transmission error according to the gear specification was different, the difference of the minimum transmission error was not large. The transmission error at the load larger than the minimum transmission error load increased to a slope similar to the slope of the analysis result.

Study on Performance of Electric Propulsion Systems for Aircraft applying Magnetic Gears (마그네틱 기어를 적용한 항공기용 전기추진 시스템의 성능 연구)

  • Sung-Hyun Lee;Rae-Eun Kim;Jung-Moo Seo
    • Journal of Aerospace System Engineering
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    • v.17 no.6
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    • pp.27-34
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    • 2023
  • This paper presents the application of a magnetic gear to the electric propulsion system for an aircraft. Since high torque is required in aircraft electric propulsion systems, combining a speed reducer can amplify the torque. However, mechanical gears have issues, such as friction, vibration, and heat generation, which lead to maintenance challenges. In the case of a direct-drive motor that does not use mechanical gears, the size and weight of the motor increase to achieve high torque. This paper proposes the application of a magnetic gear to solve the maintenance issues of mechanical gears and the weight increase problem of direct-drive motors in aircraft electric propulsion systems. In this paper, a magnetic gear suitable for aircraft electric propulsion systems is designed, and it is compared with a direct-drive motor in terms of performance and the feasibility of applying the magnetic gear is verified.

An upper-bound analysis for the guiding type forging of helical gears (헬리컬기어의 안내형 단조에 관한 상계해석)

  • Choi, J.C.;Choi, Y.;Tak, S.J.
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.21 no.9
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    • pp.1364-1372
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    • 1997
  • In this paper, the forging of helical gears has been investigated. Punch is tooth-shaped as is the die insert. The punch compresses a cylindrical billet placed in a die insert. As a consequence the material of billet flows into the tooth region. The forging has been analysed by using the upper-bound method. A kinematically admissible velocity field has been developed, wherein, an involute curve has been introduced to represent tooth profile of the gear. Numerical calculations have been carried out to investigate the effects of various parameters, such as module, number of teeth, helix angle and friction factor on the forging of helical gears. Some forging experimentswere carried out with aluminum alloy to show the validity of the analysis. Good agreement was found between the predicted values of the forging load and obtained from the experimental results.

An Upper-Bound Analysis for Closed-Die Forging of the Involute Spur Gears with Circular Arc Fillet (원호필렛-인벌류트 스퍼어 기어의 밀폐단조에 관한 상계해석)

  • Choi, J.C.;Hur, K.D.;Kim, C.H.;Choi, Y.
    • Transactions of Materials Processing
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    • v.3 no.1
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    • pp.97-109
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    • 1994
  • Closed-die forging of the spur gears with circular are fillet has been analyses by using the upper-bound method. A kinematically admissible velocity field has been developed, wherein, the tooth profile consists of the involute curve and the circular arc fillet. In the analysis, the deformation regions have been divided into eight zones. A constant frictional stress has been assumed on the contacting surfaces Utilizing the formulated velocity field, numerical calculations have been carried out to investigate the effects of various parameters, such as module, number of teeth, addendum modification coefficient and friction factor, on the relative forging pressure of spur gears. As the result of numerical calculations, the relative forging pressure does not change so much against the variation of module. On the other hand, the relative forging pressure increases at the final filling stage as the addendum modification coefficient increases.

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Vibration from a Shaft-Bearing-Plate System Due to an Axial Excitation of Helical Gears

  • Park, Chan-Il
    • Journal of Mechanical Science and Technology
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    • v.20 no.12
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    • pp.2105-2114
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    • 2006
  • In this paper, a simplified model is studied to predict analytically the vibration from the helical gear system due to an axial excitation of helical gears. The simplified model describes gear, shaft, bearing, and housing. In order to obtain the axial force of helical gears, the mesh stiffness is calculated in the load deflection relation. The axial force is obtained from the solution of the equation of motion, using the mesh stiffness. It is used as a longitudinal excitation of the shaft, which in turn drives the gear housing through the bearing. In this study, the shaft is modeled as a rod, while the bearing is modeled as a parallel spring and damper only supporting longitudinal forces. The gear housing is modeled as a clamped circular plate with viscous damping. For the modeling of this system, transfer matrices for the rod and bearing are used, using a spectral method with four pole parameters. The model is validated by finite element analysis. Using the model, parameter studies are carried out. As a result, the linearized dynamic shaft force due to the gear excitation in the frequency domain was proposed. Out-of-plan displacement from the forced vibrating circular plate and the renewed mode normalization constant of the circular plate were also proposed. In order to control the axial vibration of the helical gear system, the plate was more important than the shaft and the bearing. Finally, the effect of the dominant design parameters for the gear system can be investigated by this model.

Design of a rice transplanting mechanism with noncircular planetary-gear-train system (비원형 유성기어열을 사용한 이앙기 식부기구의 설계)

  • Bae, Kang-Yul
    • Journal of the Korean Society for Precision Engineering
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    • v.22 no.12 s.177
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    • pp.108-116
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    • 2005
  • Transplanting accuracy of a rice transplanter mainly depends on the trajectory of the hoe for picking, conveying and transplanting of seedlings as well as the return motion. The trajectory can be decided and prescribed to be suitable in treating seedlings fur a prevailing soil condition. For the purpose of the transplanting accuracy, the design of a transplanting mechanism would be carried out using a planetary-gear-train system instead of the four bar linkage system. In this study, a design method of transplanting mechanism is theoretically proposed by synthesizing a noncircular planetary-gear-train system fur the tool (hoe) to trace a prescribed trajectory. The method utilizes an optimization approach to decide the lengths of an arm and a tool, the inverse kinematics to figure out the configuration angles of the two links, the roll contact condition in transmitting motion between the gears, and a linearization approach to obtain the shapes of the gears. Based on the proposed method, the shapes of the gears and the lengths of the tools of the planetary-gear-train system are determined fur three prescribed trajectories. A kinematical simulation with a commercialized package program is also carried out to confirm that the gear-train system synthesized with the proposed method is able to trace the prescribed trajectory.

Study on the Sizing System of Head Gears (모자업체의 유형별 치수체계에 관한 연구)

  • Lee, Jin-Hee;Do, Wol-Hee
    • Korean Journal of Human Ecology
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    • v.12 no.4
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    • pp.571-578
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    • 2003
  • The purpose of this research was to provide basic information for enhancing sizing suitability in terms of the need for appropriate fit in head gear. The method for this research was to survey about sizing system of head gear, basic measure part, repair service. The subject of this study were 15 head gear companies. The results of this research were as follows : 1. In the sex target analysis according to company type, most of fashion brand companies were producing woman's head gear. In case of the company to produce man's head gear, sizes appeared variously. On the other hand, the sports brand companies were producing unisex head gear and safety helmet companies were producing man's one. 2. The number of size of head gear manufacturing companies were under 3 sizing system. This means that the sizing system of current head gear manufacturing company isn't various. 3. While the measuring part using currently in the company was head girth, one to be considered necessary for manufacturing of head gear except the head girth was head height.

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Identification of Gear Noise for Industrial Robots (산업용 로봇의 기어소음 특성 고찰)

  • Kim, Dong-Hae;Lee, Jong-Moon
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2002.11b
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    • pp.152-155
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    • 2002
  • An industrial robot noise has various noise sources such as gears, motors, bearings, and controller fans. Among these, gears are the most dominant source for noise. The gear noise, caused by tooth profile, elastic deformation, machining error and wear, is directly correlated with the transmission error of mating gear. Due to the fact that has several axis and many gears, it is difficult to understand the characteristics of the vibration and noise of robots. In this study, some advanced analysis techniques based on digital signal processing such as power spectrum, time spectral map, RPM map, and etc., were applied for locating the dominant frequency components of the robot noises and identifying their sources. In addition, sound quality analysis was performed in order to evaluate the operator's annoyance. The noise and vibration measurements were carried out at several points during the operation of each axis considering the effect of load and posture of the robot. Eased on the results, proper countermeasures to reduce excessive noise level have been suggested considering the characteristics of sources.

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Developing a Simulator of the Capture Process in Towed Fishing Gears by Chaotic Fish Behavior Model and Parallel Computing

  • Kim Yong-Hae;Ha Seok-Wun;Jun Yong-Kee
    • Fisheries and Aquatic Sciences
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    • v.7 no.3
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    • pp.163-170
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    • 2004
  • A fishing simulator for towed fishing gear was investigated in order to mimic the fish behavior in capture process and investigate fishing selectivity. A fish behavior model using a psycho-hydraulic wheel activated by stimuli is established to introduce Lorenz chaos equations and a neural network system and to generate the components of realistic fish capture processes. The fish positions within the specified gear geometry are calculated from normalized intensities of the stimuli of the fishing gear components or neighboring fish and then these are related to the sensitivities and the abilities of the fish. This study is applied to four different towed gears i.e. a bottom trawl, a midwater trawl, a two-boat seine, and an anchovy boat seine and for 17 fish species as mainly caught. The Alpha cluster computer system and Fortran MPI (Message-Passing Interface) parallel programming were used for rapid calculation and mass data processing in this chaotic behavior model. The results of the simulation can be represented as animation of fish movements in relation to fishing gear using Open-GL and C graphic programming and catch data as well as selectivity analysis. The results of this simulator mimicked closely the field studies of the same gears and can therefore be used in further study of fishing gear design, predicting selectivity and indoor training systems.