• 자동차안전학회지
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• 제5권1호
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• pp.16-24
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• 2013

Some GM (General Motors) vehicles are using a GMLAN (General Motors Local Area Network) communication protocol for control and diagnostics. The airbag control module uses vehicle speed information from the GMLAN to record the vehicle speed as pre-crash information. In order to use the vehicle speed information for crash reconstruction purposes, it helps to be able to understand the accuracy of the data. The actual vehicle speed is not expected to be the same as the GMLAN indicated speed in some situations like a spin or if there is hard braking. This paper compares the actual vehicle speed and vehicle speed information during specific vehicle maneuvers. Actual vehicle speed is calculated from a GPS sensor, while GMLAN vehicle speed is calculated from transmission output sensor by the Engine control module (ECM). Vehicle maneuvers defined as Mode #1, Mode #2, Mode #3. The Mode #1 maneuver simulates wheel lock-up and skidding f by hard-braking at a specific speed. The Mode #2 maneuver simulates a 90degree turn using a J-turn maneuver at a specific speed. The Mode#3 maneuver simulates a 180 degree turn using a spin type of maneuver at a specific speed. The study then compares the GMLAN speed and GPS speed to see what speed difference exists between them. The results of this paper are applicable to GM vehicles only. This paper catalogs the performance and limitations of two vehicles as useful reference for crash reconstructions where there is a need to understand the speed indicated in the pre-crash section of the SDM data.

• 대한전자공학회논문지SD
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• 제42권2호
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• pp.23-30
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• 2005

이 논문에서는 낮은 stand-by power 및 DLL의 재동작 후 fast relocking 구조를 가지는 저전력, 고속 VISI 칩용 DLL(지연 고정 루프) 기반의 다중 클락 발생기를 제안하였다. 제안된 구조는 주파수 곱셈기를 이용하여 주파수 체배가 가능하며 시스템 클락의 듀티비에 상관없이 항상 50:50 듀티비를 위한 Duty-Cycle Correction 구조를 가지고 있다. 또한 DAC를 이용한 디지털 컨트롤 구조를 클락 시스템이 standby-mode에서 operation-mode 전환 후 빠른 relocking 동작을 보장하고 아날로그 locking 정보를 레지스터에 디지털 코드로 저장하기 위해 사용하였다. 클락 multiplication을 위한 주파수 곱셈기 구조로는 multiphase를 이용한 feed-forward duty correction 구조를 이용하여 지연 시간 없이 phase mixing으로 출력 클락의 duty error를 보정하도록 설계하였다. 본 논문에서 제안된 DLL 기반 다중 클락 발생기는 I/O 데이터 통신을 위한 외부 클락의 동기 클락과 여러 IP들을 위한 고속 및 저속 동작의 다중 클락을 제공한다. 제안된 DLL기반의 다중 클락 발생기는 $0.35-{\mu}m$ CMOS 공정으로 $1796{\mu}m\times654{\mu}m$ 면적을 가지며 동작 전압 2.3v에서 $75MHz\~550MHz$ lock 범위와 800 MHz의 최대 multiplication 주파수를 가지고 20psec 이하의 static skew를 가지도록 설계되었다.

• 대한기계학회논문집A
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• 제28권8호
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• pp.1125-1134
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• 2004

This paper presents a mathematical model which is about the dynamics of not only a two wheel steering vehicle but a four wheel steering vehicle. A sliding mode ABS control strategy and PID rear wheel control logic are developed to improve the brake and cornering performances, and enhance the stability during emergency maneuvers. The performances of the controllers are evaluated under the various driving road conditions and driving situations. The numerical study shows that the proposed full car model is sufficient to accurately predict the vehicle response. The proposed ABS controller reduces the stopping distance and increases the vehicle stability. The results also prove that the ABS controller can be employed to a four wheel steering vehicle and improves its performance. The four wheel steering vehicle with PID rear wheel controller shows increase of stability when a vehicle speed is high and sharp cornering maneuver when a vehicle speed is low compared to that of a two wheel steer vehicle.

• International Journal of Automotive Technology
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• 제8권2호
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• pp.211-217
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• 2007

The wheel slip control systems are able to control the braking force more accurately and can be adapted to different vehicles more easily than conventional ABS (Anti-lock Brake System) systems. In realizing the wheel slip control systems, real-time information such as the tire braking force at each wheel is required. In addition, the optimal target slip values need to be determined depending on the braking objectives such as minimum braking distance and stability enhancement. In this paper, a robust wheel slip controller is developed based on the adaptive sliding mode control method and an optimal target slip assignment algorithm is proposed for maximizing the braking force. An adaptive law is formulated to estimate the braking force in real-time. The wheel slip controller is designed based on the Lyapunov stability theory considering the error bounds in estimating the braking force and the brake disk-pad friction coefficient. The target slip assignment algorithm searches for the optimal target slip value based on the estimated braking force. The performance of the proposed wheel slip control system is verified in HILS (Hardware-In-the-Loop Simulator) experiments and demonstrates the effectiveness of the wheel slip control in various road conditions.

• 한국소음진동공학회논문집
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• 제20권10호
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• pp.976-982
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• 2010

This paper proposes a novel type of pressure control mechanism which can apply to vehicle ABS (anti-lock braking system) utilizing the piezoactuator based valve system associated with the pressure modulator. As a first step, a flapper-nozzle of a pneumatic valve system is devised by integrating the piezoacuator to the flexible beam structure. The dynamic modeling of the valve system is then undertaken and subsequently the governing equation of pressure control is derived considering the pressure modulator. A sliding mode controller is designed in order to achieve accurate pressure tracking control in the presence of actuator uncertainty as well as input pressure variation. It is shown through computer simulation that an accurate pressure tracking for sinusoidal motion whose magnitude is 40 bar is achieved by utilizing the proposed pressure control mechanism.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2005년도 추계종합학술대회
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• pp.845-848
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• 2005

This paper describes a 4.224GHz CMOS charge pump PLL for Mode 1 MB-OFDM UWB hopping carrier generation. It includes a qudrature VCO of which the frequency range is from 3.98GHz to 4.47GHz(@ 0.4 to 1.5 V), a divider, a PFD, a loop filter, a charge pump, and a lock detector. Designed in a 0.18um CMOS technology, the PLL draws 6.6mA from a 1.8V supply. The phase noise of the designed VCO is -133dBc/Hz@3MHz.

• 한국자동차공학회논문집
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• 제20권1호
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• pp.112-118
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• 2012

The electronic wedge brake is one of the brake-by-wire systems with a self-energizing effect. The electronic wedge brake has faster response than the conventional hydraulic brake and requires only about one-tenth the power to operate. However, the electronic wedge brake cannot be implemented unless the self-energizing effect is reliably controlled. The self-energizing mechanisms may result in unintentional lock up and are very sensitive to environment and parametric variations of the friction coefficient. In this study, the electronic wedge brake is modeled into dynamic equations, and a sliding mode controller is designed based on the model. The performance of the proposed controller is verified in simulations.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2001년도 춘계학술대회논문집
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• pp.484-489
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• 2001

Recent trends in information storage devices disk are the transition from CD drives to high density DVD drives, the development of writable disk drives and the appearance of several high-density portable disk drives. In some flexible disk drives, self-excited disk vibrations become severe as rotation speed increases near or above critical speed. Critical speeds of CD/DVD, ASMO and floppy disks are experimentally measured and compared with analytical predictions. Flutter instability caused by aero-induced disk vibration at high speeds are experimentally observed. In ASMO, three nodal-diameter mode experiences its flutter at 8750 rpm with the frequency lock-on phenomenon. The CD/DVD disk does not have the aero-induce flutter up to 14,000 rpm.

• 한국광학회지
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• 제10권6호
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• pp.507-511
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• 1999

10 Gbit/s급의 모드-록킹된 광섬유 레이저 신호로부터 반도체 광 증폭기의 4광파 혼합신호를 이용하여 10GHz로 위상 동기된 신호를 얻었다. 제작된 위상 동기 회로는 8시간 이상 성공적으로 안정되게 동작되었고, 위상 동기 주파수 작동 범위는 입력 광펄스 주파수의 30KHz 이내로 측정되었다.

• 한국광학회지
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• 제4권3호
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• pp.347-353
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• 1993

펌프-촉침 방법을 이용한 피코초 순간 흡광 속도분광기를 제작하고 피코초 순간 흡광 분광을 측정하는 다른 방법들과 비교하였다. 제작된 피코초 순간 흡광 속도분광기는 모드 록킹된 cw 색소 레이저에서 발생된 펌프 펄스와 촉침 펄스 사이의 지연시간 변화에 따른 시료의 순간 투과도를 잡금 증폭기를 사용하여 측정하였다. 이 속도분광기를 사용하여 측정된 순간 흡광 및 바닥 상태의 표백 재생 속도 곡선들을 보여주었다. 단일 파장에서 발광 또는 비발광 계의 순간 흡광 혹은 바닥 상태의 표백 재생의 아주 좋은 속도 곡선을 얻을 수 있었다.