• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2004.10a
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• pp.298-303
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• 2004

The active magnetic bearing system for a TMP consists of four couples of magnets, five gap sensors with its amplifiers and a digital PID controller. For stabilizing and providing damping, digital PID controller is applied for each control axes and the inter-axis cross feedback controller is also applied to suppress low frequency vibration caused by gyroscopic moment of the rotor. Therefore in this paper, a digital controller of magnetic bearing for a TMP is design and examined.

• Journal of IKEEE
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• v.19 no.4
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• pp.479-485
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• 2015

A resistance deviation-to-time interval converter based on dual-slope integration using second generation current conveyors (CCIIs) is designed for connecting resistive bridge sensors with a digital system. It consists of a differential integrator using CCIIs, a voltage comparator, and a digital control logic for controlling four analog switches. Experimental results exhibit that a conversion sensitivity amounts to $15.56{\mu}s/{\Omega}$ over the resistance deviation range of $0-200{\Omega}$ and its linearity error is less than ${\pm}0.02%$. Its temperature stability is less than $220ppm/^{\circ}C$ in the temperature range of $-25-85^{\circ}C$. Power dissipation of the converter is 60.2 mW.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.661-662
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• 2007

We have carried out the construction of the 154kV intelligent substation with KEPRI. The intelligent substation is built in Gochang testing facility of KEPCO and consists of electronic instruments for GIS(gas insulated switchgear), digital control panel, remote monitoring and diagnosis system, and digital relay system. Rogowski coil type CT(RCT) and capacitive voltage divider(CVD) are introduced compared with the instrument transformer of conventional type. Digital control panel(DCP) replaces the LCP(local control panel) which is drived for mechanical operation. For the monitoring of the condition of GIS and TR, various sensors are used. In this paper, we mention the synopsis and report the progress state of project.

• Journal of the Korean Society for Precision Engineering
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• v.21 no.5
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• pp.91-98
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• 2004

Human uses level difference and time difference to get space information. Therefore this paper shows that method to presume direction of sound source by time difference and to mark presumed position. The position means direction from geometrical center of sensors to the sound source. To get the time difference of microphones input level, we will be explained about arrangement of microphones which used for the sensor to take the sound signal. It is included distance among the 3 microphones and distance between microphones and sound source. Secondly, input signals are transmitted to CPU througth digital process. CPU is used to DSP(Digital Signal Processor) for manage the signal by real time. Finally, the position of sound source is perceived by an explained algorithm in this paper.

• Proceedings of the Korean Society of Computer Information Conference
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• 2019.07a
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• pp.151-152
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• 2019

운동 기구를 이용한 운동의 경우 바른 자세와 균형을 유지하는 것이 중요하다. 이에 본 논문에서는 적외선 감지센서가 부착된 디스플레이형 전신거울과 프리웨이트 운동기구에 부착된 센서를 이용하여 이용자의 정보를 인지하고 디스플레이 장치에 출력되는 가상 트레이너를 통해 균형 운동에 대한 가이드를 제공하는 게임형 콘텐츠를 설계하였다. 본 콘텐츠의 목표는 운동 시에 중요한 바른 자세를 잡기 위하여 균형 상태를 알 수 있게 하며, 가상트레이너에 의해 보다 효과적이고 흥미로우며 지속적인 운동을 가능하게 하는 방법을 제공하는 것에 있다.

• Proceedings of the Korean Society of Computer Information Conference
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• 2019.07a
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• pp.147-148
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• 2019

최근 국민의 건강증진 및 질병관리 등에 대한 관심이 증가하면서 전문가들 또한 걷기 운동의 유효성을 강조하고 있다. 이에 따라 스마트 헬스케어와 관련된 기기 및 서비스에 대한 개발이 활발히 진행 중이다. 본 논문에서는 GPS와 비콘 센서를 이용한 환경에서 걷기운동과 미니게임 콘텐츠를 융합한 어플리케이션을 설계하고 구현한다. 이 콘텐츠는 특정 지역을 가상의 게임 맵으로 매칭하고 GPS센서와 리얼월드의 비콘을 블루투스 통신으로 인지하도록 하였으며 이를 통해 소모 칼로리 계산, 게임의 클리어 조건 등 핵심 시스템으로 사용한다. 본 연구를 통해 설계, 구현된 게임 콘텐츠는 이용자의 움직임을 정확히 측정할 수 있고 재미와 몰입감을 제공하여 지속적인 운동을 유도함으로써 운동효과가 향상됨을 확인할 수 있었다.

• Smart Structures and Systems
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• v.24 no.5
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• pp.597-606
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• 2019

Damage detection based on dynamic characteristics of a structure is one of important roles in structural damage identification. It is difficult to detect local structural damage using traditional dynamic experimental methods due to a limited number of sensors used in an experiment. In this work, a non-contact test stand of fan blades is established, and a full-field noncontact test method, combined with three-dimensional digital image correlation, Bayesian operational modal analysis, and damage indices, is used to detect local damage of a fan blade under ambient excitation without use of baseline information before structural damage. The methodology is applied to detect invisible local damage on the fan blade. Such a method has a seemingly high potential as an alternative to detect local damage of blades with complex high-precision surfaces under extreme working conditions because it is a noncontact test method and can be used under ambient excitation without human participation.

• Journal of Sensor Science and Technology
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• v.30 no.6
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• pp.388-394
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• 2021

The conventional microelectromechanical system (MEMS) process has been used to fabricate sensors with high costs and high-volume productions. Emerging 3D printing can utilize various materials and quickly fabricate a product using low-cost equipment rather than traditional manufacturing processes. 3D printing also can produce the sensor using various materials and design its sensing structure with freely optimized shapes. Hence, 3D printing is expected to be a new technology that can produce sensors on-site and respond to on-demand demand by combining it with open platform technology. Therefore, this paper reviews three standard 3D printing technologies, such as Fused Deposition Modeling (FDM), Direct Ink Writing (DIW), and Digital Light Processing (DLP), which can apply to the sensor fabrication process. The review focuses on strain/load sensors having both sensing material features and structural features as well. NCPC (Nano Carbon Piezoresistive Composite) is also introduced as a promising 3D material due to its favorable sensing characteristics.

• Journal of the Society of Naval Architects of Korea
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• v.61 no.2
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• pp.115-124
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• 2024

To detect and prevent structural damage caused by various loads on marine structures and ships, structural health monitoring procedure is essential. Estimating loads acting on the structures which are measured by sensors that are mounted properly are crucial for structural health monitoring. However, attaching an excessive number of sensors to the structure without consideration can be inefficient due to the high costs involved and the potential for inducing structural instability. In this study, we introduce a method to determine the optimal number of sensors and their optimized locations for strain measurement sensors, allowing for accurate load estimation throughout the structure using model expansion method. To estimate the loads exerted on the entire structure with minimal sensors, we construct a strain-load interpolation matrix using the strain mode shapes of the finite element (FE) model and select the optimal sensor locations by applying D-Optimal Design and the row exchange algorithm. Finally, we estimate the loads exerted on the entire structure using the model expansion method. To validate the proposed method, we compare the results obtained by applying the optimal sensor placement and model expansion method to an FE model subjected to arbitrary loads with the loads exerted on the entire FE model, demonstrating efficiency and accuracy.

• Journal of the Korean Institute of Navigation
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• v.24 no.5
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• pp.443-450
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• 2000

Before some experiments were carried out with analog bandpass filter which used for filtering the noise included in sound source signal. And this filter was constituted by condenser, register and operational amplifier. Hut these elements made the phase characteristics to differentiate in each sensing channel and cause a little of measurement error. We made new measurement system that was substituted digital filter for the analog filter in order to develop the optimal system which could find the time delay between each sensors with high accuracy. This paper describes the new system's constitution and the function of each parts. Specially three digital filters were designed and applied to the digital signal processing Part. And a series of experiments were carried out with the source＇s distance 9.53meters and the random bearing interval within the limits of $0^{\circ}$ ~ $180^{\circ}$. As a result, we have recognized that the accuracy of measurements were differentiated by the methods what kind of digital filter were adopted. And we have confirmed the facts that IIR LPF was suitable for sound source's bearing measurement and FIR LPF reduced the range measurement error.