• Transactions of the Korean Society of Automotive Engineers
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• v.4 no.2
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• pp.23-31
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• 1996

The crankshaft speed fluctuation was measured every crank angle. In order to detect the misfire, the engine and the dynamometer were considered as a single- degree of freedom system. From this modeling, the detection criteria were derived and examined by the engine test. By this method the single misfire or multiple misfires can be detected. Even on the condition of low load and higher speed than 3000rpm, where it was difficult through the other methods, misfire detection was carried out steadily. From this results, the method proposed by this paper proved reasonable.

• Transactions of the Korean Society of Automotive Engineers
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• v.4 no.2
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• pp.166-172
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• 1996

This paper presents the characteristics of the crankshaft speed fluctuations. To analyze them, the speed waveforms were measured both at the flywheel and at the front end of the engine. The speed waveform measured at the flywheel shows better result than at the front end one, because of the torsional vibration and the auxiliary components. And the patterns of the speed fluctuations are classified into three region, such as low load, middle load and high load region with the variations of the loads. Additionally, as the engine speeds increase and the loads decrease, the analysis of the speed becomes more difficult due to lower variation of the speed. And in all the regions, the main frequency component of the speed fluctuation is firing frequency.

• Proceedings of the IEEK Conference
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• 2009.05a
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• pp.270-272
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• 2009

본 연구에서는 자동차 사고나 뇌졸중 등에 의해 경추 이하의 마비나 손, 발 등의 움직임은 자유롭지 않은 사람들의 컴퓨터 사용을 돕고자 손이나 발을 이용하지 않고 머리의 움직임과 눈의 깜박임만으로 컴퓨터 마우스 제어가 가능한 장치를 제안하였다. 마우스의 좌우, 상하 이동은 각속도 센서를 이용하여 머리의 움직임으로 유발하고, 클릭과 더블 클릭은 광 센서를 시야를 방해하지 않는 위치에 장착하여 감지할 수 있도록 하였다. 제안한 마우스를 Quick Glance를 이용한 것과 비교해 보고 문자를 입력함에 있어 dasher을 이용하는 것과 윈도우에서 제공하는 화상키보드를 이용하는 것을 비교해 보았다. 공간 이동 능력과 이벤트 검출을 비교한 실험에서는 좌우, 상하 이동은 기존 마우스와 비교하여 속도 면에서는 큰 차이는 없었으나, 정확도가 조금 떨어지는 이유로 인하여 소요시간이 $3{\sim}4$배 정도 더 필요하였다. 그러나 Quick glance와 비교결과에서는 약 14%정도 빠랐고 dasher을 이용하여 문자를 입력함에 있어서도 약 32% 이상 빠르게 문자를 입력할 수 있었다. 실험 결과 눈이 쉽게 피로해지는 Quick glance를 이용하는 것보다 제안한 마우스를 사용하는 것이 더 효과적이었다.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.5 s.176
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• pp.1231-1237
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• 2000

Dynamics of a rotating cantilever beam near its critical angular speed is investigated in this paper. The external, force is idealized as a periodic function which has the same period as the rotati ng frequency of the beam. The equations of motion are derived and transformed into a dimensionless form. A prescribed spin-up motion is employed for the rotating motion. Numerical study shows that the steady state and the transient responses of the beam are affected by the spin-up time constant and there exists a time constant at which the maximum transient response becomes minimum.

• Journal of the Korean Society for Precision Engineering
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• v.24 no.10
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• pp.83-90
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• 2007

The vehicle dynamic control system needs to detect the yaw rate of vehicle and a yaw rate sensor is required as a central component. Therefore, A sensor on the basic of the "tuning fork method" for automotive controls is being developed. The sensor was fabricated by the surface micro machining process to miniaturize its size. The sensor output offset is ${\pm}0.37^{\circ}/sec$ in the room temperature. The resonance frequency of the fabricated yaw rate sensor is measured to 5.29kHz for the drive mode. Tests of the sensor demonstrate that its performance is equivalent to that required for implementation of a yaw control system. Vehicle handling and safety are substantially improved using the sensor to implement yaw control.

• Journal of Sensor Science and Technology
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• v.5 no.4
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• pp.47-56
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• 1996

The basic principle and characteristics of a DTG(dynamically tuned gyroscope) are presented in this paper, which is used for the detection of disturbance and for the stabilization of gimbal. An accurate model of the rate mode DTG is proposed. This model has a resonance characteristics which is more similar to the characteristics of practical systems than the conventional 2nd order system model. Therefore, this model is applicable to the general rate mode gyroscope. Some problems at using DTG for a real electro optical tracking system are discussed and a solution is described.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2014.10a
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• pp.457-460
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• 2014

Precession coefficient is defined by the ratio of the angular rate or rotational angle of the standing wave formed in an elastic resonator with respect to that of the platform. In this paper the precession of a hemispherical resonator due to Coriolis' effect is studied through Rayleigh-Ritz's method and Lagrangian Mechanics when the resonator undergoes Rayleigh's mode deformation. The calculation result was compared with studies by other researchers.

• Transactions of the Korean Society of Automotive Engineers
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• v.3 no.2
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• pp.42-50
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• 1995

This paper proposes a new method to investigate combustion phenomena using the variation of crankshaft speed, From the idea that the variation of crankshaft speed contains the information of combustion, the energy method is applied as a single degree of freedom. Through the comparison of measured and calculated crankshaft speed, the proposed energy model is proved to be effective. When the crankshaft speed is used in the energy equation, filtering of the speed is required. The frequency components of cylinder pressure are analyzed and the coefficients of Fourier series above the twelfth frequency of engine speed are considered as a noise. As an example of application of this research, some combustion analyses like mean effective pressure, heat release rate, and misfire detection were carried out.

• The Bulletin of The Korean Astronomical Society
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• v.37 no.2
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• pp.172.2-172.2
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• 2012

위성은 발사 후 임무수행을 위하여 자세획득 및 자세결정이 필수적이다. 저궤도 위성에서 자이로센서는 별 센서와 함께 사용되거나, 별 추적기와 사용하여 자세의 변화량을 읽고 자세제어를 수행한다. 자이로센서는 크게 전력공급부와 각속도 측정부, 그리고 전자처리부 등으로 구성된다. 위성은 발사 전 조립시험 기간 동안 전자파, 진동, 열/진공 등의 환경시험 통하여 수차례의 성능 유무를 확인한다. 본고에서는 열진공시험 전과 후, 그리고 열진공시험 진행중에 측정한 결과를 통하여, 시스템적인 측면에서의 자이로센서 건강상태 및 성능을 분석하였다. 위성시스템 상태의 자이로 시험은 자이로센서가 가질 수 있는 조합에 따라 위성의 방향에 따른 지구각속도를 확인 및 관련 데이터를 분석하였다.

• Journal of Yeungnam Medical Science
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• v.14 no.1
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• pp.101-110
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• 1997

The maximal voluntary strength of knee extension and flexion on both the right and left sides was measured in patients with hemiparesis of upper motor neuron type and in a group of normal subjects. Significant differences of maximal voluntary strength were found between male and female but the ratio of flexor to extensor strength did not vary significantly between the sides, between the sex in normal subjects. The maximal voluntary strength of uninvolved side were not reduced significantly but involved side reduced significantly in patients. The ratio of flexor to extensor strength in hemiparetic side was significantly less than the ratio for the normal subjects but not significant difference in uninvolved side of patients. According to the above results, the maximal voluntary strength of flexion was more reduced than that of the extension in lower extremity of hemiparesis patients. The strength ratio of flexion to extension was a useful parameter for guiding the rehabilitation of hemiparesis.