• Proceedings of the IEEK Conference
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• 2006.06a
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• pp.609-610
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• 2006

A 77GHz MMIC transceiver module consisting of a power amplifier, a low noise amplifier, a drive amplifier, a frequency doubler and a down-mixer has been developed for automotive forward-looking radar sensor. The MMIC chip set was fabricated using $0.15{\mu}m$ gate-length InGaAs/InAlAs/GaAs mHEMT process based on 4-inch substrate. The power amplifier demonstrated a measured small signal gain of over 20dB from $76{\sim}77GHz$ with 15.5dBm output power. The chip size is $2mm{\times}2mm$. The low noise amplifier achieved a gain of 20dB in a band between $76{\sim}77\;GHz$ with an output power of 10dBm. The chip size is $2.2mm{\times}2mm$. The driver amplifier exhibited a gain of 23dB over a $76{\sim}77\;GHz$ band with an output power of 13dBm. The chip size is $2.1mm{\times}2mm$. The frequency doubler achieved an output power of -16dBm at 76.5GHz with a conversion gain of -16dB for an input power of 10dBm and a 38.25GHz input frequency. The chip size is $1.2mm{\times}1.2mm$. The down-mixer demonstrated a measured conversion gain of over -9dB. The chip size is $1.3mm{\times}1.9mm$. The transceiver module achieved an output power of 10dBm in a band between $76{\sim}77GHz$ with a receiver P1dB of -28dBm. The module size is $8{\times}9.5{\times}2.4mm^3$. This MMIC transceiver module is suitable for the 77GHz automotive radar systems and related applications in W-band.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.15 no.2
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• pp.66-71
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• 2016

For the manual transmission gearbox used in the automotive industry, gear meshing transmission error is the main source of noise known as gear whine, and radiated gear whine noise plays an important role in the whole gearbox. Therefore, in order to keep competitive in the automotive market, the NVH performance of transmission gearboxes is increasingly important for automotive manufacturers when a new product is developed. In this paper, in order to achieve an optimized tooth contact pattern, gear tooth modification is applied to make up for the deformation of the teeth owing to load. A five-speed MT gearbox is firstly modeled in RomaxDesign software and the prediction of transmission error under the loaded torques is studied and compared. From the simulation, the transmission error and maximum contact stress are also simulated and compared after tooth modification of the loaded torques. Finally, the simulation results are used to optimize the whole gearbox design and the final gearbox prototype is testified to obtain NVH performance in a semi-anechoic room.

• Transactions of the Korean Society of Automotive Engineers
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• v.24 no.1
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• pp.112-121
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• 2016

AFLS (Adaptive front lighting system) is being applied to improve safety in driving automotive at night. Safe embedded system design for controlling head-lamps is required to improve noise robust ECU hardware and software simultaneously by considering safety requirement of hardware-dependent software under severe environmental noise. In this paper, we propose an adaptive headlight controller with a newly-designed symmetric angle sensor compensator, especially based on the proposed steering-swivel angle lookup table to determine whether the current controlling target is safe. The proposed system includes an additional backup hardware to compare the system status and provides safe swivel-angle management using a controlling algorithm based on the pre-defined lookup table (LUT), which is a symmetric mapping relationship between the requested steering angle and expected swivel angle target. The implemented system model shows that the proposed architecture effectively detects abnormal situations and restores safe status of controlling the light-angle in AFLS operations under severe noisy environment.

• Journal of the Korean Society of Safety
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• v.17 no.3
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• pp.1-6
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• 2002

A dynamic characteristics of shock absorber in the various excitation is investigated experimentally. Work diagrams and characteristic curves are used as a experimental standard. The various excitation conditions temperature and noise are very important factors in associated with the reduction of damping force. It is found that the heat occurrence from shock absorber, the gas shock absorber is much higher than oil shock absorber and increased in high speed. As to the variation of damping force, there are no change when the speed is low but we fixed amount of variation by increasing speed and change of new and old decrease. The sound pressure of the swash noise from cycle of shock absorber, we compared with theory sound pressure by experiment.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.19 no.10
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• pp.1092-1098
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• 2009

The squeal propensity of an automotive disc brake system is studied in the theoretical and computational manner. The rotating disc is in contact with two stationary pads and the nonlinear friction is engaged on the contact surface. The friction-coupled equations of motion are derived in the finite element(FE) of the actual brake disc and pad. From the general definition of friction force, the rotation and in-plane mode effects can be included properly in the brake squeal model. The eigenvalue sensitivity analysis and the mode shape visualization at squeal frequencies are also conducted for the detailed investigation. It is found that the squeal propensity is strongly influenced by rotation effect and the in-plane mode can be involved in squeal generation.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1994.10a
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• pp.217-224
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• 1994

변속기에서 발생하는 치타음을 클러치를 통하여 해결하려는 방법으로 자동차 중립시와 주행시 각기 다른 비틀림특성을 갖는 클러치를 대상으로 한 실험으로부터 엔진플라이휠, 인풋기어, 변속기 케이스의 진동을 측정하고 분석함으로써 다음과 같은 결론을 얻었다. 자동차 중립시나 주행시에 수동변속기에서 발생하는 치타음은 클러치를 통하여 해결될 수 있음을 알 수 있었다. 클러치의 프리댐퍼와 메인댐퍼의 비틀림강성과 히스테리시스는 중립시와 주행시 치타음에 대해 각기 다른 특성을 갖게 되는데 메인 댐퍼만으로 구성된 클러치는 주행시에는 치타음을 제거하는데 효과적이지만 중립시에는 인풋기어의 비틀림 공진에 의하여 변속기가 가진되어 치타음이 발생하였다. 주행시 변속기 치타음 제거효과를 감소시키지 않고 중립시 변속기에서 발생하는 치타음을 제거하기 위해 메인댐퍼만으로 이루어진 클러치디스크에 프리댐퍼 부분을 첨가하여 보았는데 자동차 주행시의 치타음 제거효과를 유지하면서 중립시의 치타음을 제거시킬 수 있다는 것을 확인하였다.

• 유체기계공업학회:학술대회논문집
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• 2006.08a
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• pp.165-168
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• 2006

Due to the distinct advantages of comfort, drive ability and fuel economy standard, the variable displacement swash plate type compressor which can control the compressor displacement by increasing of reducing the swash plate angle has developed for automotive air-conditioning system. That can be obtained constant temperature of car room on the variation cooling capacities of engine speeds. In this paper we investigated the improvement of internally controlled variable displacement swash plate compressor on noise.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.15 no.5
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• pp.80-85
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• 2016

In recent years, work to improve the power of a tractor has been in development. This study, using the mid-PTO power of a compact tractor, attempted to develop a high-speed mid-mower by setting the rotation to more than 3,000 RPM designed/manufactured major components of the high speed mid-mower. The performance of high-speed mid-mower was evaluated by the precision of straight bevel gears, and durability, the noise of the gearbox, the gearbox internal temperature, the maximum rotation speed of the mid-mowers, and the grass cutting test. Through the performance test results, the maximum number of revolutions of the mid-mower was measured over 3,000RPM, the gearbox noise and gearbox internal temperature satisfied the performance requirements of a high speed mid-mower.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.05a
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• pp.1185-1191
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• 2001

This paper discusses an experimental method for measuring the insertion loss (IL) performance of multi-layered insulations that are used in vehicles. Instead of two adjacent reverberation chambers which are generally used to measure the transmission loss (TL) of the large sound isolation materials, air-borne sound insulation tester was utilized to determine the IL and articulation index (AI) of standardized insulation materials. In comparison to reverberation chamber method, air-borne sound insulation tester method is more space-saving, more time-saving and more simple to the automotive acoustics. From the empirical results, it is found that the performances of insulation materials are closely connected with density of polyurethane foam, thickness of heavy layer, thickness of polyurethane foam, and application ratio to panel area.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.06a
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• pp.119-124
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• 2000

This paper introduces the brief guidelines on general aspects of tests and experiments with human subjects. Detailed methods for measuring whole-body vibration are reviewed for those tests and experiments and compared each other. Such comparison is found to be very useful in choosing adequate methods for human related tests and experiments. Of course, it is also expected to be very meaningful to our automotive research and industrial fields that are critical to the ride quality of their products with uncomfortable acoustic noise and vibration.