• Journal of the Korean Society for Precision Engineering
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• v.23 no.10
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• pp.14-21
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• 2006

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11a
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• pp.366.1-366
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• 2002

It is addressed that the turbulent broadband sound power from a sirocco fan can be modeled by the trailing edge noise. The trailing edge noise is usually influenced by inflow turbulence, separation, and boundary layer on the blade. The design parameters such as solidity(c/s) and stagger angle are specified to predict performance and noise level because the separation and slip velocity are strong1y affected by them along with the flow coefficient. (omitted)

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.1020-1026
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• 2011

In this paper, we propose a method that measures the height and stagger of an catenary using the laser profile images. One line laser and area scanner CCD cameras are used. To quickly and accurately extract, from a photographed image, the area of the overhead line on which the line laser is shone, we consider the established fact that the catenary is the lowest among the electric wires. Here we are solving the the distance to the catenary if we know the distance the camera is from the ground and the angle of the catenary in the field of view. The angle will be related to the number of pixels in the image. This pixels per degree is a constant for the camera. Also, because of the different pixel resolution of the camera according to the overhead line position, we compensate the measurement result through camera calibration.

• Journal of Convergence for Information Technology
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• v.8 no.5
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• pp.137-143
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• 2018

Generally, a radar signal is modulated and transmitted in order to avoid signal detection. In electronic warfare, the specification of a radar is recognized by analysing the received radar pulses. In this paper, we propose an algorithm to recognize the PRI (Pulse Repetition Interval) type of radar signals. This algorithm uses the autocorrelation technique applying different comparison ranges according to the PRI type. It applies a short comparison window to stable and staggered PRI, and a relatively large comparison range to jittered PRI. The experiment shows that the proposed algorithm can discriminate the PRI type of radar pulses correctly. For the more, it can find out the stagger level of staggered type of radar signals.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.11a
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• pp.222-222
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• 2009

Currently in electric railways, there are various test standards for catenary systems such as stability assessment standards and maintenance standards for appropriate vehicle operation. In Korea, maintenance vehicles are used to measure height, stagger, and wear of catenaries and various tests are being conducted based on maintenance manuals. In this paper, real-time data aquisition technologies for assessment of electric railway current collection status between catenaries and pantographs that are consistantely being developed from the adoption of electric railways were analyzed based on on-board measurement items.

• Proceedings of the KIEE Conference
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• 1991.11a
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• pp.366-369
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• 1991

A nonlinear controller based on feedback linearization method is proposed for an electromagnetic suspension system. After exactly linearizing the system with nonlinear feedback, linear control technique is applied. Modeling of stagger typed magnet is introduced and controlled for not only levitation, but guidance. By the feedback linearization, the nonlinear, MIMO system is linearized and decoupled, so we can use linear control law. The simulation of this system control skim is demonstrated. Robustness properties of the proposed controller with respect to the load variations and external disturbance is also analyzed for a multi input multi output system. In this properties, the boundary of variation is proposed.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2002.05a
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• pp.75-79
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• 2002

In this research, a design guideline of current generating rotor and acceptable field rotor in offshore environment is proposed. To design rotor model, wind mill rotor design principles and turbine theories were applied based on a field rotor experimental data. To verify the compatibility of the rotor design method and to analyze the properties of design factors, 3 rotor models were designed and experimented in a circular water channel. Three rotor models were designed according to different blade numbers and blade shapes. With various flow velocities and rotor rpm, the rotor power and efficiency were measured and the properties of rotor were estimated. The results can be effectively applied to the design of current generation rotor.

• Journal of the Korean Institute of Telematics and Electronics
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• v.22 no.2
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• pp.60-65
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• 1985

A method of weighting of a staggered pulse train is presented and an improvement per-formance of the signal-to-noise ratio for each case is compared. As the result of a computer simulation, the signal-to-noise ratio for weighting of a stagger-ed pulse train is a great improvement on the case of an uniform pulse train. The signal-to-noise ratio of optimum weighting is more improved than that of binomial weighting, it is known that the signal-to-noise ratio is improved as the increasing of the number of delay line cancellers, and it is shown that the signal-to-noise ratio is improved by weighting of the MTI output pulses before the integration process.

• International Journal of Fluid Machinery and Systems
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• v.1 no.1
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• pp.148-154
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• 2008

The Wells turbine rotor consists of several symmetric airfoil blades arranged around a central hub, and the stagger angle is 90 degrees. These characteristics simplify the total construction of OWC type wave energy converters. Although the Wells turbine is simple, the turbine produces a complicated flow field due to the peculiar arrangement of blades, which can rotate in the same direction irrespective of the oscillating airflow. In order to understand these flows, flow visualization is carried out with an oil-film method in the water tunnel. This research aims to analyze the mechanism of the 3-D flows around the turbine with the flow visualization. The flow visualization explained the influence of attack angle, the difference between fan-shaped and rectangular wings, and the sweep angle.

• Transactions of the Korean Society of Mechanical Engineers
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• v.15 no.5
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• pp.1620-1634
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• 1991

본 연구에서는 전기/자기 및 기계적 요소들이 복합되어 이루어진 자기부상 시 스템의 설현을 위한 기초단계로서 제어동역학(controlled dynamics) 측면에 입각한 모 델식을 본드선도 기법을 이용하여 보다 조직적으로 유도한다. 우선, 자속흐름 확장 및 자속 유출량을 고려하여 부상 시스템을 모델링하고 차량/레일 및 2차 현가(second ary suspension)장치를 포함한 자기부상 시스템을 모델링한다. 다음, 지지 및 안내 방향의 동역학을 동시에 고려한 2차원 자기부상 시스템을 본드선도의 다접점 필드(mu- ltiport field) 개념을 이용하여 모델링한다. 끝으로, 본드선도 기법으로 모델링된 2차원 자기부상 시스템의 안정도와 성능을 향상시키기 위하여 LOG/LTR(linear quadra- tic Gaussian control with loop transfer recovery) 제어시스템을 설계한다. LQG/ LTR 제어방법은 Doyle과 Stein에 의해 인성(stability-robustness) 문제와 주파수역 성능을 설계시에 직접 고려할 수 있는 강력한 선형 다변수 제어시스템 설곕방법으로 현재 널리 사용되고 있다.