• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2000년도 추계학술발표대회 논문집
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• pp.124-127
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• 2000

In this study, a technique for monitoring of fatigue damage of composite laminates by measuring the stiffness change using embedded intensity-based optical fiber sensors was investigated. Firstly, the underlying measurement principle and structure of intensity-based sensors and then a simple stiffness conversion process was explained. The monitoring technique was evaluated by fatigue tests of composite laminates with an embedded intensity-based sensor. From the test results, the response of the intensity-based sensor showed good correlation with that of surface mounted extensometer. Therefore, it can be concluded that the intensity-based sensors have good potential for the monitoring of fatigue damage of composite structures under fatigue loading. In addition, it could be confirmed that the intensity-based sensors have higher resistance to fatigue than the commercial electrical strain gauge.

• 한국표면공학회지
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• 제29권5호
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• pp.459-466
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• 1996

A great amount of effort has been devoted to the constant improvement of such basic performance as dirvability, safety and enviromental protection. As a result, the total combination of various technologies has made it possible to produce safer and more comfortable automobiles. Among these technologies, plasma and thin film techniques are mainly cocerned with sensors, optics, electronics and surface modification. This paper first describes a concept of thin film processing in materials synthesis for sensors based on particle-surface interaction during deposition to provide a long life sensor applicable to sutomobiles. Some examples of parctical application of thin films to sensors are then given. These include(1) a thin films strain gauge for gravity sensors, (2) a giant magneto resistance film for speen sensors, and (3) a Magneto-impedance sensors fordetection of low magnetic field. Further progress of sophisticated thin film technology must be considered in detail to explore advanced thin film materials science and to ensure the field reliability of future sensor devices for automobile.

• 대한금속재료학회지
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• 제56권11호
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• pp.835-843
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• 2018

In this work, we report a delta rosette strain sensor based on highly stretchable silver nanowire (AgNW) percolation piezoresistors. The proposed rosette strain sensors were easily prepared by a facile two-step fabrication route. First, three identical AgNW piezoresistive electrodes were patterned in a simple and precise manner on a donor film using a solution-processed drop-coating of the AgNWs in conjunction with a tape-type shadow mask. The patterned AgNW electrodes were then entirely transferred to an elastomeric substrate while embedding them in the polymer matrix. The fabricated stretchable AgNW piezoresistors could be operated at up to 20% strain without electrical or mechanical failure, showing a maximum gauge factor as high as 5.3, low hysteresis, and high linearity ($r^2{\approx}0.996$). Moreover, the sensor responses were also found to be highly stable and reversible even under repeated strain loading/unloading for up to 1000 cycles at a maximum tensile strain of 20%, mainly due to the mechanical stability of the AgNW/elastomer composites. In addition, both the magnitude and direction of the principal strain could be precisely characterized by configuring three identical AgNW piezoresistors in a delta rosette form, representing the potential for employing the devices as a multidimensional strain sensor in various practical applications.

• 한국항행학회논문지
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• 제23권2호
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• pp.200-206
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• 2019

산업현장에서의 지게차의 전복에 의한 안전사고 빈도가 매우 높은 편이다. 지게차 전복의 가장 큰 원인은 과적으로, 이를 방지하기 위해서 적재 중량을 측정해야 한다. 가장 보편적인 적재 중량 측정 방식은 로드셀(load cell)로 측정 오차가 적은 장점이 있지만 설치 단가가 비싸다는 점 때문에 산업현장에 쉽게 적용하지 못하고 있다. 본 연구는 로드 셀 방식의 대안으로 제시되었지만 측량 정밀도가 높지 않은 strain gauge 센싱 방식을 적용한 지게차 새로운 적재 중량 측정 시스템을 제안한다. 센서의 측량 정밀도와 내구성을 높이기 위해 4개의 센서가 각각 4개의 anchor bolt에 삽입되는 구조로 제작하였다. 제작된 anchor 볼트 형태의 strain gauge 센서를 지게차에 적용하여 측정한 결과 1%의 측정 오차를 얻을 수 있었다.

• Structural Monitoring and Maintenance
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• 제4권1호
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• pp.1-15
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• 2017

Installation of sensors networks for continuous in-service monitoring of structures and their efficiency conditions is a current research trend of paramount interest. On-line monitoring systems could be strategically useful for road infrastructures, which are expected to perform efficiently and be self-diagnostic, also in emergency scenarios. This work researches damage detection in composite concrete-steel structures that are typical for highway overpasses and bridges. The techniques herein proposed assume that typical damage in the deck occurs in form of delamination and cracking, and that it affects the peak power spectral density of dynamic curvature. The investigation is performed by combining results of measurements collected by long-gauge fiber optic strain sensors installed on monitored structure and a statistic approach. A finite element model has been also prepared and validated for deepening peculiar aspects of the investigation and the availability of the method. The proposed method for real time applications is able to detect a documented unusual behavior (e.g., damage or deterioration) through long-gauge fiber optic strain sensors measurements and a probabilistic study of the dynamic curvature power spectral density.

• 한국마린엔지니어링학회:학술대회논문집
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• 한국마린엔지니어링학회 2005년도 후기학술대회논문집
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• pp.202-203
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• 2005

we present a pressure sensor based on the mechanically formed long-period fiber gratings. The attenuation properties of an output power as a function of an external pressure is able to apply to the in-line fiber pressure sensors for the vessels.

• 대한토목학회논문집
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• 제28권5A호
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• pp.699-707
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• 2008

교량구조물의 안전성 평가에 있어서 처짐형상을 측정하는 것은 매우 중요한 요소이다. 그러나 교량의 처짐을 측정하는 작업은 일반적으로 용이하지 않으며, 경우에 따라서 측정점이 제한되거나 많은 비용이 소요된다. 따라서 최근에 광섬유 변형률센서를 이용한 교량의 처짐형상을 간접적으로 추정하는 연구가 진행되고 있으나 단순지지 형식의 교량에 주로 적용되고 있다. 본 연구에서는 현수교의 고전적인 처짐이론을 적용하여 측정된 변형률로부터 처짐형상을 추정하는 기법을 제시하였으며, 이에 대한 검증을 위하여 남해대교를 대상으로 현장 재하시험을 수행하였다. 남해대교 보강형 내부에 부착한 FBG 변형률센서를 이용하여 변형률을 계측하였으며, 제안한 추정기법을 적용하여 얻어진 처짐형상을 정밀측량데이터 및 구조해석결과와 비교분석하였다. 결과적으로 본 연구에서 제안한 현수교 처짐형상 추정기법의 적용가능성을 검증하였으며, FBG 변형률센서의 현장 적용성을 확인하였다.

• 전자통신동향분석
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• 제33권1호
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• pp.123-130
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• 2018

Tactile sensors, which are commonly referred to as pressure and strain sensors, have been extensively investigated to meet the demands for attachable and wearable electronics for monitoring the health status or activity of human users. For this purpose, the introduction of two-dimensional (2D) materials such as graphene and transition metal dichalcogenides (TMDs) with high mechanical strength at the atomic scale is very suitable for tactile sensors applicable for use in human-friendly devices. In this paper, we examine a descriptive summary of a tactile sensor and review state-of- the-art research trends of 2D material-based tactile sensors in terms of the material and architecture. Finally, we propose a roadmap for future studies into advanced tactile sensors based on our ongoing research.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2007년도 춘계학술대회논문집
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• pp.938-942
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• 2007

The proposed algorithm tries to localize damage in a structure by monitoring abnormal increases in strain measurements from a group of wireless sensors. Initially, this clustering technique provides an effective sensor placement within a structure. Sensor clustering also assigns a certain number of master sensors in each cluster so that they can constantly monitor the structural health of a structure. By adopting a voting system, a group of wireless sensors iteratively forages for a damage location as they can be activated as needed. Numerical simulation demonstrates that the newly developed searching algorithm implemented on wireless sensors successfully localizes stiffness damage in a plate through the local level reconfigurable function of smart sensors.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2005년도 봄학술 발표회 논문집(I)
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• pp.47-50
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• 2005

Fiber Bragg Grating (FBG) Sensors as advanced measuring system are introduced and actively being applied to establish a smart monitoring system for bridge maintenance. This study develops FBG sensors and suggests a smart monitoring system. As for its first step, to verify the reliability of FBG sensors that developed, a specimen is made FBG sensors and electric sensor are attached. Then, Static test is conducted on the specimen on the specimens to check reliability. In addition, this study estimates the optimum deflection curve that converts strain curve data measured by FBG sensors into deflection.