• Journal of Biosystems Engineering
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• 제27권2호
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• pp.79-88
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• 2002

This study was conducted to develop system for high speed rice transplanting machines. The control system includes a sensor detecting the tilt angle of the seedling bed, a micro-controller and a hydraulic system consisting of a double acting cylinder, a four-way three-position solenoid valve, a relief valve and a hydraulic pump. The levelling system shared the pump with the existing steering control, resulting in a tandem center circuit for the steering and levelling control systems. Using the input signal from the sensor, the micro-controller determined and generated the output signal to control the cylinder through the solenoid valve to keep the seedling bed always parallel to the water surface regardless of soil unevenness during the transplanting operations. Both an ON/OFF and a PWM control schemes were tested. When the flow rate was more than 1 ι/min in the ON/OFF control, the system showed unstable rolling. However, in the PWM control, the system worked stably although the flow rate was more than 1 ι/min. The PWM control showed a better performance when a large difference between the angle and the dead band of the control system occurred. The characteristics of tile system response to given tilt angles were predicted by a computer simulation. Both the ON/OFF and the PWM control systems worked well providing that the operating and waiting times were properly adjusted.

• 한국분무공학회지
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• 제17권1호
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• pp.14-19
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• 2012

The present study conducts experimental investigation on spreading and deposition characteristics of a $4.3{\mu}l$ de-ionized (DI) water droplet impacting upon aluminum (Al 6061) flat and textured surfaces. The micro-textured surface consisted the micro-hole arrays (hole diameter: $125{\mu}m$, hole depth: $125{\mu}m$) fabricated by the conventional micro-computer numerical control (${\mu}$-CNC) milling machine process. We examined the surface effect of texture area fraction ${\varphi}_s$ ranging from 0 to 0.57 and impact velocity of droplet ranging from 0.40 m/s to 1.45 m/s on spreading and deposition characteristics from captured images. We used a high-speed camera to capture sequential images for investigate spreading characteristics and the image sensor to capture image of final equilibrium deposition droplet for analyze spreading diameter and contact angle. We found that the deposition droplet on textured surfaces have different wetting states. When the impact velocity is low, the non-wetting state partially exists, whereas over 0.64 m/s of impact velocity, totally wetting state is more prominent due to the increase kinetic energy of impinging droplet.

• 센서학회지
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• 제22권2호
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• pp.100-104
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• 2013

A superhydrophobic mesh is a unique structure that blocks water, while allowing gases, sound waves, and energy to pass through the holes in the mesh. This mesh is used in various devices, such as gas- and energy-permeable waterproof membranes for underwater sensors and electronic devices. However, it is difficult to fabricate micro- and nano-structures on three-dimensional surfaces, such as the cylindrical surface of a wire mesh. In this research, we successfully produced a superhydrophobic water-repellent mesh with a high contact angle (> $150^{\circ}$) for nanofibrous structures. Conducting polymer (CP) composite nanofibers were evenly coated on a stainless steel mesh surface, to create a superhydrophobic mesh with a pore size of $100{\mu}m$. The nanofiber structure could be controlled by the deposition time. As the deposition time increased, a high-density, hierarchical nanofiber structure was deposited on the mesh. The mesh surface was then coated with Teflon, to reduce the surface energy. The fabricated mesh had a static water contact angle of $163^{\circ}$, and a water-pressure resistance of 1.92 kPa.

• 한국정보통신학회논문지
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• 제23권11호
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• pp.1364-1370
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• 2019

건축물이나 교량, 터널과 같은 구조물의 붕괴를 측정하기 위하여 기울기 센서를 사용하고 있으며 최근에는 사용성이 편리하고 가격이 저렴하여 MEMS(Micro-Electro-Mechanical System) 센서를 사용한 기울기 센서를 많이 사용하고 있으나 측정 범위가 한정되어 있어 360도 전 방위에 대해 고정밀도를 가지지는 못하고 있다. 이것은 MEMS 센서가 갖는 오프셋과 스케일 오차 때문이다. 본 논문에서는 MEMS 센서가 갖는 기계적 오차를 줄이기 위하여 정밀도가 높은 각도 계산을 위한 알고리즘을 제시하였고 MEMS 센서 모듈과 전송 모듈을 제작하여 교정 전 센서 모듈의 각도 정확도와 교정 후 각도 측정 정확도를 비교하여 교정 알고리즘의 효과를 제시하였으며, 실험 결과 제안 기술을 적용하였을 때 360도 전 방위에 대해 ±0.015도의 정밀도를 가짐을 확인하였다.

• Composites Research
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• 제24권6호
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• pp.12-17
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• 2011

자체-센서와 미세 작동기 응용을 위한 CNT와 ITO로 코팅된 나노복합재료의 계면접착 내구성과 전기적 특성을 평가하였다. 나노복합재료의 접착 및 계면 내구성은 반복하중 피로시험에 따른 전기저항도를 측정하여 평가하였다. CNT와 ITO의 고유 전기적 특성으로 인하여 CNT가 코팅된 PVDF 나노복합재료는 ITO가 코팅된 경우보다 다소 낮은 전기저항도를 나타내었으나, 모두 양호한 자체-감지능을 보여주었다. CNT/PVDF와 ITO/PVDF 나노복합재료 모두 계면 내구성은 양호함을 확인하였다. 정적 접촉각 시험을 통해 CNT와 ITO 그리고 PVDF간의 표면에너지, 접착일, 그리고 퍼짐계수를 평가하여 계면 내구성과 의 상호 관련성을 확인하였다. 수용액에서 CNT와 ITO로 코팅된 PVDF 시편의 최적의 작동성은 주파수와 전압을 달리하여 레이져 변위센서를 사용한 연신율 변화로 측정하였다. 작동된 두 나노복합재료들의 연신율은 주파수가 증가함에 따라 감소하며, 반면에 전압의 증가에 따라 상승하였다. 각 나노복합재료의 나노구조 및 고유의 전기적 특성으로 인하여, CNT/PVDF가 ITO/PVDF 보다 자체-감지 및 작동기로서 더 적합하다는 것을 알 수 있었다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1997년도 하계학술대회 논문집 B
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• pp.593-596
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• 1997

The main purpose of this paper is to develop sensing device of joint angle using loss of opfical fiber. The source of light to optical fiber is infrared rays diode, and receiver is a photo transistor. The bent angle of optical fiber is measured with rotary encoder, and The change of voltage due to the loss of light is measured with micro computer PIC16C74. The sensing device may be used to Functional Electrical stimulation(FES) System for Rehabilitation patient.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 학술대회 논문집 정보 및 제어부문
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• pp.318-319
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• 2008

In this paper, a steering feel simulator is designed and implemented using a steering wheel with a rotation angle sensor, torque sensor, and an ac motor for the generation of the required torque. The controller in the simulator consists of a 16-bit micro-controller, a D/A converter and A/D converters. The main objective of the controller is to perform torque control where the reference torque is calculated from the torque map for both the vehicle velocity and the wheel sensor cutout. It is shown via the experimentation using the proposed simulator that the simulator output performance can be easily understood for the variation of vehicle parameters or controller parameters.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년 학술대회 논문집 정보 및 제어부문
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• pp.582-584
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• 2006

This paper describes a monocular PSD-based motion capture sensor to employ with commercial video game systems such as Microsoft's XBOX and Sony's Playstation II. The system compact, low-cost, and only requires a one-time calibration at the factory. The system includes a PSD(Position Sensitive Detector) and active infrared (IR) LED markers that are placed on the object to be tracked. The PSD sensor is placed in the focal plane of a wide-angle lens. The micro-controller calculates the 3D position of the markers using only the measured intensity and 2D position on the PSD. A series of experiments were performed to evaluate the performance of our prototype system. From the experimental results we see that the proposed system's compact size, low-cost, ease of installation, and high frame rates are suitable for high speed motion tracking in games.

• Journal of Astronomy and Space Sciences
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• 제22권1호
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• pp.47-58
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• 2005

This paper addresses development of the ultra-light analog sun sensors for small satellite applications. The sun sensor is suitable for attitude determination for small satellite because of its small, light, low-cost, and low power consumption characteristics. The sun sensor is designed, manufactured and characteristic-tested with the target requirements of ${\pm}60^{\circ}$ FOV (Field of View) and pointing accuracy of ${\pm}2^{\circ}$. Since the sun sensor has nonlinear characteristics between output measurement voltage and incident angle of sunlight, a higher order calibration equation is required for error correction. The error was calculated by using a polynomial calibration equation that was computed by the least square method obtained from the measured voltages vs. angles characteristics. Finally, the accuracies of 1-axis and 2-axes sun sensors, which consist of 2 detectors, are compared.

• 센서학회지
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• 제15권3호
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• pp.153-157
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• 2006

This paper presents the method for three-dimensional micro structure with photoresist spray coating system. The system consists of a high temperature rotational chuck, ultrasonic spray nozzle module, angle control module and nozzle moving module. Spray coating system is effected by several parameters such as the solid contents, the dispensed volume, the scanning speed of the spray nozzle and the wafer of dimension. The photoresist (AZ 1512) has been coated on the three-dimensional micro structure by spray coating system and the characteristics have been evaluated.