• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.25 no.12
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• pp.815-821
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• 2015

Maritime safety has been more critical recently due to the occurrence of shipboard accidents involving prime movers. As such, the propulsion shafting design and construction plays a vital role in the safe operation of the vessel other than focusing on being cost-efficient. Smaller vessels propulsion shafting system normally install high speed four-stroke diesel engine with reduction gear for propulsion efficiency. Due to higher cylinder combustion pressures, flexible couplings are employed to reduce the increased vibratory torque. In this paper, an actual vibration measurement and theoretical analysis was carried out on a propulsion shafting with V18.3L engine installed on small car-ferry and revealed higher torsional vibration. Hence, a rubber-block type flexible coupling was installed to attenuate the transmitted vibratory torque. Considering the flexible coupling application factor, reduction gear stability due to torque variation was analyzed in accordance with IACS(International Association of Classification Societies) M56 and the results are presented herein.

• 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.

• Journal of the Korean Society for Precision Engineering
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• v.28 no.3
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• pp.370-376
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• 2011

Recently, the application range of plastic gears is widely expanding by the development of engineering plastics with good mechanical properties. Plastic gears have excellent performances such as light weight, water resistance and vibration absorbing ability for metallic gears. In this study, the optimization of injection molding process was done for the large disk type plastic gears of auto phoropter. Design Of Experiment (Taguchi method) was adopted to find a tendency of molding conditions that influence the flatness of disk type gear. Four main factors for molding conditions were selected based on injection temperature, filling time, packing pressure and mold temperature. Also, Filling, packing and cooling analyses were carried out to evaluate Z directional deflection of large disk type gear by using the simulation software (Moldflow) based on the DOE. From the results, it was found that the injection temperature and packing pressure are the most sensitive parameters for the Z directional deflection of large disk type gears.

• Transactions of the Korean Society of Mechanical Engineers
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• v.10 no.6
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• pp.870-875
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• 1986

In this study, full-rounded tip curve of rack and its mating fillet curve of pinion in Involute-circular arc composite tooth profile are derived. Mechanical characteristics are calculated analytically, i.e., Specific sliding, Nominal bending stress at working root circle and the Contact factor of the arc of contact in circular arc part to the arc of double contact. These characteristics compared with standard involute tooth profile are improved in circular arc part of composite tooth profile. To obtain more efficient composite tooth profile, we studied these characteristics with regard to the changes of unwound angle and radius of circualr arc. And a design method of composite tooth profile is suggested. Composite tooth profile are compared with standard involute tooth profile.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.12 no.12
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• pp.921-928
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• 2002

Main sources of the nitration of a gear-pair system are backlash and transmission error, the difference between required and actual rotation during gear meshing. This paper presents the nonlinear dynamic characteristics of gear motions due to the existence of backlash and periodic variation of meshing stiffness, which is assumed as a one-term harmonic component. Gear motions are classified as three types with the consideration of backlash. Each response is calculated using the harmonic balance method and confirmed by numerical integration. The responses with the increase of the rotating speed show abrupt changes in its magnitude for the variation of the preload, exciting force, and damping coefficient. The result also shows that there is a chaotic motion with some specific design parameters and operating conditions In gear diving system. Consequently the design of gear driving system with low nitration and noise requires the study on the effects of nonlinear dynamic characteristics due to stiffness variation and backlash.

• The Journal of the Korea institute of electronic communication sciences
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• v.18 no.5
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• pp.835-840
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• 2023

Compared to 3D FEM, 2D FEM can be analyzed by simplifying the model and conditions. However, with respect to coil conditions, in many cases, direction of coils(upward, downward, entrance, exit, etc.) are sequentially configured and set up the FEM analysis conditions. This paper shows simplification of coil conditions and reduction of analysis time by applying the equivalent winding method composed of one FEM coil even if it has multiple slots, and shows consistency of results by applying it to a winding type magnetic gear.

• Transactions of the Korean Society of Mechanical Engineers
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• v.3 no.3
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• pp.124-131
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• 1979

An optimim reduction gear ratio problem for a subway rapid transit car in Seoul was solved by using a computer program package, which is a modified and extened version of the simple model by Mischke. The optimum value of reduction gear ratio was evaluated by minimizing the total start-to stop time.The validity of the computer program package was verified by cross-checking the calculated values of gear ratio and dynamic characteristics with the actual and measured values.

• Journal of the korean Society of Automotive Engineers
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• v.5 no.1
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• pp.24-31
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• 1983

혼합기 어큐물레이터를 부착시킨 연소실에 관한 새로운 아이디어를 고찰하였다. "혼합기어큐물 레이터실 (Mixture Accumulator Chamber; MA Chamber)"로 명명한 이 연소실은 점화전 압축 행정중에 부하상태와 관계없이 내부의 가한 기체난류를 일으킬 수 있다. 이러한 기관(MA engine)의 성능과 그 특성을 연구하였다. 그 기관의 베이스기관(base engine)에 비하여 기관압 축비를 증가시킬 수 있고 희박혼합기로서 안정연소를 시킬 수 있음이 확실하다. 있음이 확실하다.

• Journal of the KSME
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• v.54 no.7
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• pp.40-45
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• 2014

풍력발전시스템은 육상용에서 해상용으로 개발되며 대형화하고 있는 추세이다. 풍력발전시스템이 해상용 등으로 대형화되면서 유지, 보수에 높은 비용이 소요되고 이에 따라 신뢰성을 확보하기 위한 요구가 더 커지고 있다. 증속기의 경우 고장 빈도도 낮지 않고, 고장 발생 시 심각도가 높아 신뢰성이 가장 높게 요구된다. 최근 증속기의 신뢰성을 확보하기 위한 연구 개발에서 수명에 가장 영항을 크게 미치는 조건으로 적용하중 영향에 대한 비토크 하중(non-torque load)과 유성기어열의 설계 인자로 취급되는 하중 분할(load sharing), 치면 하중 분포(face-load distribution) 그리고 이를 필수적으로 입증하고자 요구되는 시험/평가 기술에 대하여 소개하고자 한다.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11a
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• pp.311.1-311
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• 2002

To reduce the vibration of a gear driving system, the modification of gear tooth from the orignal involute gear profile is usually done in gear manufacturers. The quantity of the tooth modification has been decided on the basis of the intereference between two gear teeth during gear meshing and the elastic deformation due to loading. (omitted)