• 한국철도학회:학술대회논문집
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• 한국철도학회 2007년도 춘계학술대회 논문집
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• pp.477-485
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• 2007

When Korean High Speed Train (KTX) runs over a high-speed railway bridge, the high-speed railway bridge gives quite large acceleration response. Local vibration at the large cross section, the impact from equally spaced sleepers, the vibration due to elastomeric bearings, and the vibration from the train itself are the causes of this acceleration response. Maximum peaks of the accelerations measured at the bridges are sometimes going over the limit value. Although it is smaller than 0.35G, the limit from the Korean Bridge Design Manual(BRDM), this acceleration response should be reduced for the safety of running trains with high speed. In this paper, to reduce the acceleration response by controlling excessive local vibration at the large cross section, vibration reduction method is studied. The result shows that the effect of elastomeric bearings on the vibration of the bridge is very large and that the vibration reduction device is effective against wing mode local vibration PSC box girder bridge for the high-speed railway, which usually has very large cross section, although it has little effect on global vibration modes such as flexural and twisting modes. The test of the vibration reduction device on the bridge in service has been performed in this study.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2007년도 추계학술대회논문집
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• pp.1022-1027
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• 2007

This paper presents a method to analyze the unbalance response of a high speed polygon mirror scanner motor supported by sintered metal bearing and flexible structures by using the finite element method and the mode superposition method considering the asymmetry of the gyroscopic effect and sintered metal bearing. The eigenvalues and eigenvectors are calculated by solving the eigenvalue problem and the adjoint eigenvalue problem by using the restarted Arnoldi iteration method. The decoupled equations of motion can be obtained from global finite element motion equations by using the orthogonal relation between the right eigenvectors and left eigenvectors. The decoupled equations of motion are used to analyze the unbalance response of a high speed polygon mirror scanner motor. The validity of the proposed method is verified by comparing the simulated unbalance response with the experimental results.

• 한국통신학회논문지
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• 제23권7호
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• pp.1817-1823
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• 1998

이 논문에서는 비통기식 데이터 압축의 국제 표준으로 되어있는 Lempel-Ziv-Welch 부호의 일종인 V.42bis 방식을 데이터의 고속 전송에 적용할 경우 압축 과정에서 나타나는 여러 현상들을 분석하고 이에 맞는 변형기법을 제안한다. 제안된 기법은 압축률을 결정하는 중요한 요인중의 하나인 부호책의 크기를 최적화하고, 부호책의 갱신 방법을 개선하여 압축률을 향상시킨다. 또 빈번한 압축 형식 전환에서 오는 문제점을 분석하고 형식 전환에 사용되는 문턱값 조절로 이를 어느정도 개선하여, 압축률의 시간에 따른 변화를 줄인다는 측면에서 성능 향상을 이루었다. 후자의 개선은 데이터의 고속 전송시에 완충기(buffer) 설계 및 제어에 중요한 기여를 한다.

• 조명전기설비학회논문지
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• 제16권2호
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• pp.71-80
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• 2002

영구자석형 선형동기전동기(PMLSM)는 고속, 고추력의 직선추진이 가능하므로 산업현장에서 위치결정장치나 물류반송시스템 및 공작기계 등의 선형 서보 시스템에 이용이 되고 있다. 본 논문에서는 PMLSM의 AC 서보화를 위해 동기 프레임상에서 제어구조가 미리 설정된 스위칭 함수에 따라 불연속적으로 변화되는 가변구조 전류제어방식 및 간접 벡터제어이론을 기본으로하여 도달시간을 제거하고, 구동시스템의 추력 이용도를 높이기 위해 파라미터 변동과 한정된 외란에 거의 영향을 받지 않으며 오버슈트가 없는 고속응답을 실현하기 위해 슬라이딩 모드제어 알고리즘을 제안하여 PMLSM의 위치제어에 적용하고자 한다.

• 센서학회지
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• 제23권5호
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• pp.332-336
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• 2014

In this paper, we propose a complementary metal oxide semiconductor (CMOS) binary image sensor with a gate/body-tied (GBT) PMOSFET-type photodetector for high-speed operation. The GBT photodetector of an active pixel sensor (APS) consists of a floating gate ($n^+$-polysilicon) tied to the body (n-well) of the PMOSFET. The p-n junction photodiode that is used in a conventional APS has a good dynamic range but low photosensitivity. On the other hand, a high-gain GBT photodetector has a high level of photosensitivity but a narrow dynamic range. In addition, the pixel size of the GBT photodetector APS is less than that of the conventional photodiode APS because of its use of a PMOSFET-type photodetector, enabling increased image resolution. A CMOS binary image sensor can be designed with simple circuits, as a complex analog to digital converter (ADC) is not required for binary processing. Because of this feature, the binary image sensor has low power consumption and high speed, with the ability to switch back and forth between a binary mode and an analog mode. The proposed CMOS binary image sensor was simulated and designed using a standard CMOS $0.18{\mu}m$ process.

• 한국기계가공학회지
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• 제10권5호
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• pp.20-25
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• 2011

In this paper, we reviewed the spindle system's motor and bearing and its mode safety for optimal design of a high speed spindle system that exceeds DmN value of 1,500,000. We could verify that it has a separation margin during critical speed by performing critical speed analysis. Also, we have selected an optimal sensoring installation location and actually manufactured & installed the sensor by identifying the stress concentration position in the axial load through finite element analysis to install the built-in piezo electric type load sensor to the spindle housing that can measure and monitor the machining load during high speed rotation of the spindle. Reproducibility is also verified by calibrating the error through the sensor's sensitivity adjustment after comparing the output between the plate dynamoneters and the load sensor to confirm the reproducibility of the load sensor.

• 제어로봇시스템학회논문지
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• 제6권6호
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• pp.471-477
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• 2000

The position control accuracy of a robot arm is significantly deteriorated when a long arm robot is operated at a high speed. In this case, the robot arm must be modeled as a flexible structure, not a rigid one, and its control system should be designed with its elastic modes taken into account. In this paper, the tip position control scheme of a one-link flexible manipulator using 2-DOF controller with sliding mode is presented. The robot consists of a flexible arm manufactured with a thin aluminium plate, an AC servo motor with a harmonic drive for speed reduction, an optical encoder and a CCD camera as a vision sensor for on-line measuring the tip deflection of the flexible m. Simulation and experimental results of the flexible manipulator with a proposed controller are provided to show the effectiveness of the controller.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 제36회 하계학술대회 논문집 B
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• pp.1276-1278
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• 2005

In this paper, we propose an adaptive sliding mode observer-based control of induction motors with uncertainties. The proposed adaptive sliding mode flux observer generates estimates both for the unknown parameters(load torque and rotor resistance) and for the unmeasured state variable (rotor fluxes); they converge to the corresponding true value under persistency of excitation which actually holds in typical operating conditions. The proposed controller guarantees speed tracking and bounded signals for every initial condition of the motor. Simulations show that all estimation errors tend quickly to zero so that high tracking performances are achieved both for speed and rotor flux.

• ETRI Journal
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• 제26권3호
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• pp.189-194
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• 2004

We demonstrate a high-speed recording based on field-induced manipulation in combination with an optical reading of recorded bits on Au cluster films using the atomic force microscope (AFM) and the near-field scanning optical microscope (NSOM). We reproduced 50 nm-sized mounds by applying short electrical pulses to conducting tips in a non-contact mode as a writing process. The recorded marks were then optically read using bent fiber probes in a transmission mode. A strong enhancement of light transmission is attributed to the local surface plasmon excitation on the protruded dots.

• 대한조선학회논문집
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• 제49권2호
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• pp.146-150
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• 2012

Free vibrations of strings due to initial conditions have been analyzed by the conventional mode summation method, and the nondimensionalized displacements and velocities have been derived in the form of infinite series. The results show wave propagating phenomena and confirmed by experiments using the high speed camera. Other physical characteristics have been discussed and examined with help of waveform solutions.