• 한국기계가공학회지
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• 제18권10호
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• pp.8-19
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• 2019

In this study, the spray pattern of a centrifugal fertilizer distributor with two shutter holes was analyzed and an effective driving width that satisfies proper spray uniformity was derived. The centrifugal fertilizer distributor was mounted on a tractor with a rated power of 23.7 kW and static and dynamic spray pattern tests were performed according to the standard procedure proposed by the American Society of Agricultural and Biological Engineers Standard ASAE S341.5. The height of the fertilizer distributor was 80 cm from the ground and the PTO (power take-off) shaft speed of the tractor was fixed at 540 rpm. The fertilizer scattered in space was collected using 275 evenly spaced collectors at shutter opening ratios of 25%, 50%, 75%, and 100%. The spray pattern was analyzed via the amount of sprayed fertilizer at each collector location and the coefficient of variation was used as an indicator of spray uniformity. Using the analyzed spray pattern, the effective driving width that satisfied less than 15% of the coefficient of variation was derived for different tractor driving patterns (race track mode, back and forth mode). From the results, spray uniformity increased as the shutter opening ratio decreased. The largest effective driving width was 8 m at a shutter opening ratio of 25% for both driving patterns.

• 한국ITS학회 논문지
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• 제22권6호
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• pp.264-283
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• 2023

자율주행차량 사고는 일반차량 사고와 다르게 기술적 문제, 환경, 운전자와의 상호작용 등 다양한 요인에 기인한 사고 발생 가능성이 존재한다. 향후 자율주행 기술의 진보로 기존의 사고원인 이외에도 새로운 이슈들이 대두될 것으로 예상되며, 이에 대응하기 위한 다양한 시나리오 기반의 접근법이 필요하다. 본 연구에서는 자율주행 사고 리포트인, CA DMV collision report와 자율주행모드 해제 보고서인 Disengagement report, 자율주행 실제 사고영상을 수집하여 자율주행차량 교통사고 시나리오를 개발하였다. 시나리오는 ISO 26262의 기능안전 시스템 failure mode에 기반하여 도출되었으며, 자율주행 기능의 다양한 이슈를 반영하고자 하였다. 본 연구를 통해 도출된 자율주행차량 시나리오는 향후 다양한 자율주행차량 교통사고 예방과 대비에 기여할 뿐만 아니라 자율주행 기술의 안전성을 향상시키는 데 중요한 역할을 할 것으로 기대한다.

• 한국자동차공학회논문집
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• 제14권4호
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• pp.68-76
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• 2006

The minimization of maximum DPF wall temperature and the fast Light-off during regeneration are the targets for the high durability of the DPF system and the high efficiency of regeneration. In order to predict transient thermal response of DPF, one-channel numerical modeling has been adopted. The effect of the ratio of length to diameter(L/D), cell density, the amount of soot loading on temporal thermal response and regeneration characteristics has been numerically investigated under two different running conditions: city driving mode and high speed mode. The results indicate that the maximum wall temperature of DPF increase with increasing 'L/D' in 'High speed mode'. For 'City driving mode', the maximum wall temperature decreases with increasing 'L/D' in the range of $'L/D{\geq}0.6'$. The maximum temperature decreases with increasing cell density because heat conduction and heat capacity are increased. It is also found that the effect of amount of soot loading on light-off time is negligible.

• 한국자동차공학회논문집
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• 제20권6호
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• pp.61-66
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• 2012

Conventional method to transform vehicle driving condition to engine operation mode is to use vehicle road load under neutral gear and mechanical efficiency of drivetrain. But this method requires additional measurement of efficiency of drivetrain on a test rig. And this measurement is normally done at fixed speed and thus estimated accuracy of engine operation mode is not considered to be high enough. This study suggests new method to calculate engine operation mode for prescribed driving mode such as NEDC using vehicle coastdown test under gear engaged condition without measurement of mechanical efficiency of drivetrain. Coastdown test was done under neutral and gear engaged condition for comparison and also trial to extract mechanical loss of drivetrain was carried out. Calculated engine torque by conventional and newly suggested method was compared with actually measured torque of a vehicle on a chassis dynamometer during NEDC. Newly suggested method showed slightly higher accuracy of accumulated brake work during NEDC.

• 한국자동차공학회논문집
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• 제24권6호
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• pp.694-701
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• 2016

According to revolutionary developments in automobile technologies, eco-friendly advanced vehicles (hybrid vehicle, hydrogen fuel-cell vehicle, electric vehicle, etc.) are rapidly increasing. The electromagnetic compatibility is getting more important for development of a vehicle because those advanced vehicles are driven by electric energy and equipped with more electric systems. In general, electromagnetic compatibility tests consist of an electromagnetic interference(EMI) test and an electromagnetic susceptibility(EMS) test. EMI test of the electric vehicles are needed not only in driving mode but also in charging mode because they must be recharged by much electric energy for driving. Depending on vehicle manufacturers, the charging device type and the location of charging device inlet in electric vehicles are various. In this paper, in order to investigate EMI of electric vehicles in charging mode in consideration of the direction of measuring antenna and the location of charging device inlet, a series of electromagnetic emission tests are conducted using three electric vehicles (neighborhood electric vehicle, electric vehicle and electric vehicle-bus). The test results show that electromagnetic emission measurements in charging mode are dependent on the direction of measuring antenna and the location of charging device inlet.

• 한국정밀공학회지
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• 제18권1호
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• pp.89-97
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• 2001

A microgyroscope, which vibrates in two orthogonal axes on the substrate plane, is designed and fabricated. The shuttle mass of the vibrating gyroscope consists of two parts. The one is outer shuttle mass which vibrates in driving mode guided by four folded springs attached to anchors. And the other is inner shuttle mass which vibrates in driving mode as the outer frame does and also can vibrate in sensing mode guided by four folded springs attached to the outer shuttle mass. Due to the directions of vibrating mode, it is possible to fabricate the gyroscope with simplified process by using polysilicon on insulator structure. Fabrication processes of the microgyroscope are composed of anisotropic silicon etching by RIE, gas-phase etching (GPE) of the buried sacrificial oxide layer, metal electrode formation. An eletromechanical model of the vibrating microgyroscope was modeled and bandwidth characteristics of the gyroscope operates at DC 4V and AC 0.1V in a vacuum chamber of 100mtorr. The detection circuit consists of a discrete sense amplifier and a noise canceling circuit. Using the evaluated electromechanical model, an operating condition for high performance of the gyroscope is obtained.

• 한국자동차공학회논문집
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• 제16권1호
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• pp.144-151
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• 2008

The bi-modal vehicle is composed of two car-bodies and three axles. Each axle of the vehicle has an independent suspension and all wheels are steerable. Since the bi-modal vehicle has longer wheelbase than most urban buses, the All-Wheel-Steering(AWS) system is adapted for to ensure safe driving and proper turning radius on a curved road. This paper proposes an AWS control algorithm for stable driving of bi-modal vehicle. Steering angles and directions of each axle of bi-modal vehicle changed according to the driving environment and steering modes. In the case that front and rear axles should be steered in opposite directions is a negative mode, and the other case that the axles should be steered in the same direction is a positive mode. For example, in the positive mode, front and real axles are steered in the same direction, while in the negative mode, they are steered in the opposite direction. A multibody model of the vehicle is used to verify the performance of the steering algorithm and simulation results of 2WS are compared with those of AWS under the same condition.

• Journal of Power Electronics
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• 제9권6호
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• pp.960-968
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• 2009

This paper presents a design optimization process for interior permanent magnet synchronous motors (IPMSM) for hybrid electric compressors (HEC) which are applied to hybrid electrical vehicles. A hybrid electric compressor is composed of an electric motor driving section and an engine driving section which is connected to the engine by a pulley belt. A hybrid electric compressor driving motor requires half of the full driving power of a compressor. Even though an engine is not operated at the idling stop mode, the electric motor drives the air-conditioner compressor by itself so that the air conditioning system can produce its minimum cooling capacity. In this paper, the design optimization of an IPMSM for a 42 (V) applied voltage system is studied using the design of experiment (DOE) and response surface method (RSM) of 6sigma. The driving characteristics of this motor drive system are measured and analyzed by experiment.

• International Journal of Automotive Technology
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• 제5권2호
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• pp.109-114
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• 2004

This paper presents a closed-loop evaluation of the Vehicle Stability Control (VSC) system using a vehicle simulator. Human driver-VSC interactions have been investigated under realistic operating conditions in the laboratory. Braking control inputs for vehicle stability enhancement have been directly derived from the sliding control law based on vehicle planar motion equations with differential braking. A driving simulator has been validated using actual vehicle driving test data. Real-time human-in-the loop simulation results in realistic driving situations have shown that the proposed controller reduces driving effort and enhances vehicle stability.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2001년도 ICCAS
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• pp.167.3-167
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• 2001

In this paper, a single degree-of freedom gimbal-structured micro gyroscope and signal processing part including capacitive sensing circuits and filters are designed, fabricated and experimented. We use capacitive sensing method with excitation signal, i.e. sensing excitation signal, to measure the displacement of the moving plate. So, Sensing Output Signal is modulated twice by the excitation signal and driving signal, which is profitable to decouple the driving and sensing mode, to reduce the effect of the acceleration, and to curtail the noises due to parasitic capacitance and driving signal. To reduce driving noises and to improve linearity, the excitation signals and driving signals are modified. Through frequency response analyses ...