• Transactions of the Korean Society of Automotive Engineers
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• v.3 no.2
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• pp.102-111
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• 1995

The non-periodic fluctuation of the engine torque appears to be the major source of the torsional vibration of the automotive driveline. The reduction of this torsional vibration has become a significant problem along with the requirements of higher performance. The torsional vibration of the automotive driveline can be reduced by smoothing the fluctuation by adjusting the torsional characteristics of the clutch-disc. Computer simulation of the driveline is a useful investigative tool on studying the torsional characteristics of the clutch-disc. In this paper, a dynamic model for the automotive driveline was developed, and the engine torque of the model were evaluated with experimental data. By executing a simulation using the model, it has become possible to obtain the clutch-disc torsional characteristics for reducting the torsional vibration at creeping.

• Journal of the Korean Society of Mechanical Technology
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• v.13 no.3
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• pp.17-23
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• 2011

To estimate fuel consumption of a vehicle, a car can be tested on chassis dynamometer. In this case, test causes a lot of time and money. To predict the fuel efficiency of vehicles in the design stage or early stage of development, the development of computer simulation model is necessary. Using simulation to predict the fuel consumption, the driving model which consists of time-velocity profile and time-grade profile is necessary In this study, vehicle model is developed in MatLab/simulink to estimate real driving fuel consumption rate with time-velocity profile, time-shift gear profile and time-grade profile. Vehicle model consists of driver model, engine model, power train model, and so on. On-road vehicle tests to verify the vehicle model are carried out for analyzing the result of simulation and comparing with those of the experiments.

• Journal of Advanced Marine Engineering and Technology
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• v.32 no.8
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• pp.1149-1156
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• 2008

The principle of self clamping friction clutch is presented in this paper and the transmitted torque capacity is also calculated. In order to enlarge the friction force, a part of rotating force of driving side is converted to normal force of friction materials by clamping arm. The increased normal force of friction materials assures the large friction force and the transmitted torque capacity of clutch becomes large. The self clamping friction clutch is adopted in the tube type air pressure clutch and the condition of stability is investigated. It is proven that the inclined angle of clamping arm and the friction factor of friction materials are the essential elements in stability and torque capacity of self clamping friction clutch. The transmitted torque capacity of self clamping friction clutch is compared with air pressure clutch. The normal force of friction lining is magnified by 1/(1-k) and the transmitted torque capacity is also magnified with same proportion comparing with air pressure clutch. The larger the friction factor of friction lining, the larger the magnification factor. The longer the clamping arm, the smaller the magnification factor. It must be also noted that the value of k=${\mu}Y/X$ is the criterion of stability. If the value of k=${\mu}Y/X$ is greater than or equal to 1, the self clamping friction clutch is unstable and it can not be used as clutch.

• The Journal of the Korea institute of electronic communication sciences
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• v.13 no.6
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• pp.1235-1242
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• 2018

When the wind speed changes rapidly, the wind turbine is stopped for the safety of the power system and the mechanical system. At that moment, the wind turbine gearbox is damaged and broken due to the contact load of the gearbox. In addition, the problems such as increasing frictional heat and deteriorate of the brake occur, because the power of the blades is transmitted directly to the brakes. This paper proposes a hybrid magnetic gear shape that solves the problem caused by the contact of the mechanical gear, which is the power transmission device of the wind power generation system, and the power cutoff system. The shape of the hybrid magnetic gearsuitable for the wind power generation system is derived through the torque and loss analysis according to the shape of the hybrid magnetic gear by using the two dimensional finite analysis method.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.39 no.11
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• pp.1183-1189
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• 2015

This study focuses on the design of the tapered joints of a wind power turbine. The main variables of the tapered joint are the transmitted torque, shaft diameter, contact area of the tapered ring, and tightening torque of the bolts, which applies a compressive pressure from the hub to the shaft. The stress distribution of the taper fit was calculated under axisymmetric plane strain conditions because of the small taper angle. The axial displacement of the clamp can be calculated from the radial elastic deformation and the taper angle. The stress field of each ring is obtained from the cylinder stress equation. To verify the accuracy of the calculation, finite element (FE) analysis was performed, and the results of the calculation and FE analysis were compared. The hoop stress of the tapered surface showed a discrepancy of approximately 10, but the trends of the stress distributions of each component and the relative movement obtained by FE analysis were in good agreement with the analytical calculation results.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.40 no.11
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• pp.979-986
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• 2016

The tripod shafts of constant-velocity joint are used in both the trains KTX and KTX-sanchon. It is an important component that connects the motor reduction unit and the axle reduction unit in a power bogie. The tripod shaft not only transmits drive and brake torque in the rotational direction, but also slides in the axial direction. If the drive system is loaded with an excessive torque, the fuse part of the shaft will be fractured firstly to protect the other important components. In this study, a rig was developed for conducting torsion tests on the tripod shaft, which is a type of mechanical fuse. The tripod shafts were subjected to torsional fracture test and torsional fatigue test on the rig. The weak zone of the tripod shaft was identified, and its fatigue life was predicted using finite element analysis (FEA). After analyzing the FEA results, design solutions were proposed to improve the strength and fatigue life of the tripod shaft. Furthermore, the deterioration trend and time for failure of the tripod shaft were verified using the hysteresis loops which had been changed with the advancement of the torsional fatigue test.

• Transactions of the Korean Society of Mechanical Engineers
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• v.19 no.1
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• pp.132-141
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• 1995

The torque converter, an important component of automatic transmissions, is a hydrodynamic device which has a great influence on transient characteristics of vehicle during shift. To predict the accurate driving performance in extremely transient state such as shifting process, a detailed analysis of the torque converter is required. In this study, one dimensional performance model of the torque converter based on the concept of mean flow path, was used to analyze the shifting transients and the exact values of equivalent parameters were determined from the experimental results by using BOX program. The dynamic modelings of the components of power transmission systems such as engines, planetary gear systems, clutches and one-way clutches, were carried out. To analyze the shifting transients of tracked vehicle, a simulation program was developed. In the modeling of power transmission systems, the stiffness of shafts was neglected and shifting control logic(TCU) was included. Using the developed simulation program, the driving conditions were simulated and the results of simulation were verified through the experiments on the dynamometer.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.300.1-300.1
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• 2016

최근 반도체 회로의 미세화로 인해 디자인 공정이 20 nm 이하로 내려갔다. 그 결과 회로간의 간격이 줄었으며 많은 문제가 발생 한다. 첫 번째 문제는 미세하게 여러 박막 층들을 쌓기 때문에 박막 층이 그전 50 nm 공정에 비해선 쉽게 무너질 수 있다. 따라서 하나의 박막 층은 다른 여러 박막들의 하중을 잘 견뎌야 할 것이다. 결과적으로 회로의 미세화에 따라 박막의 기계적 특성이 좋아야 될 것이다. 또 다른 문제는 너무 좁은 회로의 간격으로 인해 다른 회로에 영향을 미치는 크로스토크라는 전기적 문제이다. 크로스토크가 크다는 것은 회로간의 누설 전류가 크다는 것을 의미하며 그만큼 신호 전달 능력이 감소 한다는 것을 뜻한다. 크로스토크의 문제점을 해결하기 위해 회로 사이에 절연 막을 만들어 누설전류를 막아야 한다. 이러한 문제를 바탕으로 본 연구는 Zirconium nitride (ZrN) 박막이 이러한 문제점을 해결 할 수 있는 지연구해 보았다. 박막 제작 시 변화 요인은 질소유량 과 열처리 온도 이며 질소유량 변화는 2 sccm 과 8 sccm 두 경우로 하였다. 또한 열처리는 As-deposited state, $600^{\circ}C$ 와 $800^{\circ}C$로 열처리 하였다. 박막 증착은 RF magnetron sputtering을 이용하였으며 열처리는 질소 분위기에서 furnace를 이용하였다. 기계적 특성분석 결과 질소유량이 2 sccm 인 박막의 hardness는 as-deposited stste에서 18.8 GPa이고 $600^{\circ}C$에선 18.4 GPa로 거의 비슷하고 $800^{\circ}C$ 열처리한 경우는 15.4 GPa 으로 hardness가 감소하는 것을 알 수 있었다. 질소 유량을 8 sccm 흘려주며 증착한 박막의 경우는 as-deposited state, $600^{\circ}C$, $800^{\circ}C$에서의 hardness가 각각 17.5, 16.4, 21.1 GPa 으로 감소하다가 증가하는 경향을 보였다. 또한 zrN 박막의 전기적 특성인 누설 전류 밀도도 측정하였다. 결과적으로 본 연구는 ZrN 박막의 질소 유량 변화와 열처리에 따른 기계적, 전기적 특성변화를 확인 하였다.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.26 no.4
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• pp.293-300
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• 2013

In this study we proposed a simplified finite element model of anchor bolt system inserted through concrete structures considering clamping forces. The three different finite element types using LS-DYNA are applied for numerical efficiency of the anchor bolt modeling. Combined beam and solid elements are used to reflect the tension state at internal part of anchor bolt due to torques. The clamping forces due to torques are considered by introducing a compression for a nut plane modeled by beam elements. The numerical examples show good agreement with different element types. Parametric studies are focused on the various effects of different element types on the induced axial and shear forces of anchor bolts considering clamping forces.

• Journal of Advanced Marine Engineering and Technology
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• v.38 no.3
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• pp.262-268
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• 2014

This research introduces the structural design and the validation results of the flexible high speed coupling for 2MW class wind turbine which transmit and cut off torque between gear box and generator. The high speed coupling requires electrical insulation to prevent electrical surface damages on gear box. Therefore glass fiber reinforced plastics is applied to absorb the vibration and deformation of power train and to transmit required torque. Finite element analysis was performed to optimize the thickness and accumulation number of glass fiber reinforced plastics. Torque limiter which cut off the abnormal torque is designed in frictional disc type. The design of the coupling was validated with the performance test of prototype.