• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.6
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• pp.104-109
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• 2018

Generally, the durability of the parking lock gear is evaluated through an endurance test for the entire transmission but no test standard exists for the durability test of one part of a parking lock gear. Therefore, in this study, the durability test standards of the parking lock gear were determined autonomously, and the durability performance test was conducted. A static fracture test was carried out to determine the yield strength of the parking lock gear, and a durability test condition was set to 60 % of the yield strength. The durability test of 1,000,000 times was conducted under the given conditions using a dedicated test jig manufactured for the test. Because the jig fractured during the static fracture test, finite element analysis for the jig was carried out and the jig was re-designed. The modified jig was manufactured and the durability test was carried out based on the test standard of autonomously. The basic data on the performance and endurance limit of the parking lock gear were obtained using these tests and analyses, and the basic data will be used as fundamental materials for the design and the development of the parking lock gear.

• Agricultural and Biosystems Engineering
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• v.7 no.1
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• pp.13-17
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• 2006

The planocentric gear, known as wobble mechanism, has been used for speed reducing mechanism as an ingenious mechanism. The modem application can be found in the backrest adjusting mechanism of a vehicle reclinable seat, fluid pumps and aircraft hoist and winches. Higher speed reduction ratios, high load capacity, lower weight, and compactness are the main advantages of this gear. This paper presents velocity and static force analysis to investigate the friction lock of the planocentric gear. The rectilinear tooth profile is used to maximize the speed reduction ratio. The equivalent linkage system is used for the analysis of instantaneous motion. As the results, the transmission efficiency of the planocentric gear is found and the friction lock of the system is determined for the friction coefficients of journals. A numerical example that illustrates the developed analysis is presented.

• Transactions of the Korean Society of Automotive Engineers
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• v.14 no.2
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• pp.9-15
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• 2006

Experiments are conducted to compare fuel economy of FTP-75 mode on two different lock-up conditions; (A) Lock-up on at engine speed of 1,200(rpm) and above for 3rd & 4th gear, (B) Lock-up on at engine speed of 1400rpm and above for 4th gear only. As a result, case A had better fuel economy about 2.75(%) than case B for FTP-75 mode. Simulation(CRUISE, AVL) study is also carried out in order to estimate the effect of Lock-up control strategy for vehicle fuel economy. The fuel economy simulation result agrees with the measured fuel economy within error of 2(%). The improved Lock-up control strategy is proposed by simulation.

• Journal of Biosystems Engineering
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• v.36 no.6
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• pp.422-433
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• 2011

Market demand for hydro-mechanical transmission (HMT) for agricultural tractors has increased recently. To select a type of HMT satisfying design conditions, performance characteristics of 12 HMT types must be understood. This study was conducted to provide tractor engineers with a guideline to select the most appropriate HMT type for their design requirements. Characteristics on speed reduction ratio, power transmission efficiency, power regeneration, lock-up angular velocity, output torque ratio and torque ratio of planetary gear train axis of the 12 HMT types were investigated and presented as either formula or graphical forms. A guideline to select proper HMT type was also presented using 2 parameter: lock-up angular velocity (${\omega}_L$) and torque ratio of the planetary gear train axis. In addition, effect of gear ratio of the planetary gear train on the power transmission efficiency was investigated and a guideline to select the best gear ratio was also presented.

• Transactions of Materials Processing
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• v.17 no.2
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• pp.124-129
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• 2008

Net shape forging technologies give many effects into the costs and qualities for the finished products. So, the studies to reduce the additional machining amount are very important in forging industry. Specially, there are two main topics in cold forging industry, such as, tool life and precision forging. In this study, new forging technique was proposed to eliminate the machining process for fixing up the length and improve the lead accuracy of gear. The luck-up hub is manufactured through many processes, such as upsetting, piercing and direct extrusion. The gear is formed in direct extrusion process; however, lead accuracy of the gear is over allowance limit. Therefore, the additional sizing process must be added. In this study, process design for closed-die forging of a lock-up hub used for a component of automobile transmission was made using three-dimensional finite element simulations, and the strain distributions and velocity distributions are investigated through the post processor. The rigid-plastic finite-element method for back pressure forging has been used in order to reduce development time and die cost. Using the FEM simulation, we found the optimum value of back pressure. The prototypes of lock-up hub parts were forged into the net-shape. In the experiment, lead precision of tooth are measured by the CCMM(Contact Coordinate Measuring Machine). The dimensional accuracy of forged part was improved up to the 40% when back press was applied.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.38 no.4
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• pp.18-26
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• 2001

In this paper, we propose an ATC(Automatic Transfer mode Controller) algorithm and an average-mode-change method for use in Gear shift PLL which can automatically change loop gain. The proposed ATC algorithm accurately detects proper timing or the mode change and has a very simpler structure - than the conventional lock detector algorithm often used in QPSK. And the proposed average mode change method can obtain low errors of estimated frequency offset by averaging the loop filter output of frequency component in shift register. These algorithms are also useful in designing ASIC, since these algorithms occupy small circuit area and are adaptable for high speed digital processing. We also present phase tracking performance of proposed Gear-shift PLL, which is composed of polarity decision PD, ATC and average mode change circuit, and analyze the results by examining constellation at each mode.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.30 no.10 s.253
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• pp.1284-1292
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• 2006

Heat treatment is a controlled heating and cooling process to improve the physical and/or mechanical properties of metal products without changing their shapes. Today finite element method is widely used to simulate lots of manufacturing processes including heat treatment and surface hardening processes, which aims to reduce the number of time- and cost-consuming experimental tryouts. In this study we tried, using this method, to simulate the full carburizing process that consists of carburizing, diffusing and quenching, and to predict the distribution of carbon contents, phase fraction and hardness, thermal deformation and other mechanical characteristics as the results. In the finite element analysis deformation, heat transfer, phase transformation and diffusion effects are taken into consideration. The carburizing process of a lock gear, a part of the car seat recliner, that is manufactured by the fine blanking process is adopted as the analysis model. The numerical results are discussed and partly compared with experimental data. And a combination of process parameters that is expected to give the highest surface hardness is proposed on the basis of this discussion.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.1
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• pp.91-96
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• 2012

The retract actuator makes the landing gear retract or extend during take-off and landing of an aircraft. To prevent folding of landing gear that has remained in the extended state because of an unexpected external disturbance, an internal locking device is applied to the retract actuator. The locking device is restrained with another internal component by oil pressure supplied to the retract actuator, and this restraint makes the locking of the actuator possible. Because locking and unlocking are repeated during retraction and extension of the landing gear, the locking device takes repeated identical loads, and the possibility of fatigue failure exists. In this study, the process and results of fatigue analysis for the locking device are presented, and the appropriateness of the analysis result is verified using a fatigue test.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.131-136
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• 2004

The limited slip differential(LSD) is a device which enables the driving force to be transmitted from one slipping wheel to another wheel in such case that the car is stuck in clay or snow. When the unwanted slipping occurs on one wheel, the LSD temporarily restraints the differential motion to transmit the driving force in the other wheel. So far, many types of LSD were developed such as mechanical lock type, disk clutch type, viscous coupling type, torsion type and multiple clutch type. However these types of LSD is too complicated and expensive, so it is used only for 4WD outdoor vehicles, military vehicles, and a portion of deluxe car. So, many studies has been devoted to improve new types of LSD to cover those demerits of existing LSDs that the hydraulic LSD is developed as arepresentative result of that. The hydraulic LSD which uses the principle of gear pump is packed with viscous oil in tight container. When a slip occurs on one wheel, the hydraulic LSD generates torque caused by high oil pressure in the container. This study has been devoted to suggest an improved hydraulic LSD. In order to achieve it, we designed a new type of hydraulic LSD, produced it and did a rig test with it on real vehicle. From the rig test, it has been confirmed that the new type of hydraulic LSD can be directly applied to exiting vehicles without changing the design criteria

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.244-249
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• 2008

It happened a failure on special bolt which supported main landing gear actuator up-lock rod of 00 aircraft. Fracture was occurred at end of center drilled hole and thread machined on bolt. Metallographic, fractographic, and other characteristics of embrittlement analysis and experiments carried out on the failed bolt to find out the reason. Bolt surface was cadmium electroplated(EP) to give lubrication and provide excellent corrosion resistance. Resultly, Bolt was failed due to cadmium embrittlement occurred during baking treatment as well as center drilled hole. for the failure that are relevant to failure analysis and prevention. For their successful functional application, cadmium EP bolts require proper and adequate baking treatment after electroplating, and is complete with no center drilled hole