• KIPS Transactions on Software and Data Engineering
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• v.2 no.9
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• pp.629-642
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• 2013

Recently, with the advent of smart phones, it brought many changes in lives of modern people. Especially, application utilizing the sensor information of smart phone, which provides the service adapted by user situations, has been emerged. Sensor data of smart phone can be used for recognizing the user situation, Because it is closely related to the behavior and habits of the user. currently, GPS sensor one of mobile sensor has been utilized a lot to recognize basic user activity. But, depending on the user situation, activity recognition system cannot receive GPS signal, and also not collect received data. So utilization is reduced. In this paper, for solving this problem, we suggest a method of user activity recognition that focused on the accelerometer sensor data using smart phone. Accelerometer sensor is stable to collect the data and it's sensitive to user behavior. Finally this paper suggests a noble approach to use state transition diagrams which represent the natural flow of user activity changes for enhancing the accuracy of user activity recognition.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.4A
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• pp.639-645
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• 2006

FRP (Fiber Reinforced Polymer) is an excellent new constructional material in resistibility to corrosion, high intensity, resistibility to fatigue, and plasticity. FBG (Fiber Bragg Grating) sensor is widely used at present as a smart sensor due to lots of advantages such as electric resistance, small-sized material, and high durability. However, with insufficiency of measuring displacement, FBG sensor is used only as a sensor measuring physical properties like strain or temperature. In this study, FRP and FBG sensors are to be hybridized, which could lead to the development of a smart FRP rod. Moreover, developing the estimated model for deflection with neural network method, with the data measured through FBG sensor, could make conquest of a disadvantage of FBG sensor - uniquely used for sensing strain. Artificial neural network is MLP (Multi-layer perceptron), trained within error rate of 0.001. Nonlinear object function and back-propagation algorithm is applied to training and this model is verified with the measured axial displacement through UTM and the estimated numerical values.

• Journal of rehabilitation welfare engineering & assistive technology
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• v.9 no.3
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• pp.245-250
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• 2015

Portable devices, such as smart phones and personal digital assistants (PDAs) play an important role in our everyday life. In this paper, we propose a step count algorithm based on SVM(signal vector magnitude) and a adaptive threshold processing to monitor the physical activity. The algorithm measures a user's step counts using the smart phone's inbuilt accelerometer and g sensor. Experiment results showed the proposed algorithm has good performance in accuracy and adaptability than the app on your smart phone.

• Smart Structures and Systems
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• v.12 no.3_4
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• pp.381-397
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• 2013

In this paper, wireless health monitoring of stay cables using piezoelectric strain sensors and a smart skin technique is presented. For the cables, tension forces are estimated to examine their health status from vibration features with consideration of temperature effects. The following approaches are implemented to achieve the objective. Firstly, the tension force estimation utilizing the piezoelectric sensor-embedded smart skin is presented. A temperature correlation model to recalculate the tension force at a temperature of interest is designed by correlating the change in cable's dynamic features and temperature variation. Secondly, the wireless health monitoring system for stay cables is described. A piezoelectric strain sensor node and a tension force monitoring software which is embedded in the sensor are designed. Finally, the feasibility of the proposed monitoring technique is evaluated on stay cables of the Hwamyung Grand Bridge in Busan, Korea.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.17 no.4
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• pp.49-59
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• 2017

Smart sensing plays a key role in a variety of IoT applications, and its importance is growing more and more together with the development of artificial intelligence. Therefore the importance of smart sensors cannot be overemphasized. However, most studies related to smart sensors have been focusing on specific application purposes, for example, security, energy saving, monitoring, and there are not much effort on researches on how to efficiently configure various types of smart sensors to be needed in the future. In this paper, a component-based framework with hierarchical structure for efficient construction of smart sensor is proposed and its application to smart home is designed and implemented. The proposed method shows that various types of smart sensors to be appeared in the near future can be configured through the design and development of necessary components within the proposed software framework. In addition, since it has a layered architecture, the configuration of the smart sensor can be expanded by inserting the internal or external layers. In particular, it is possible to independently design the internal and external modules when designing an IoT application service through connection with the external device layer. A small-scale smart home system is designed and implemented using the proposed method, and a home cloud operating as an external layer, is further designed to accommodate and manage multiple smart homes. By developing and thus adding the components of each layer, it will be possible to efficiently extend the range of applications such as smart cars, smart buildings, smart factories an so on.

• Journal of Korea Multimedia Society
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• v.17 no.8
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• pp.1020-1024
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• 2014

The environment information such as dust, temperature, humidity, illumination and gas are very important in daily life. We implemented multi-sensor system which made for measuring an environment by using Arduino, ZigBee, and Appinventor. We also designed a packet for transmitting environment data. The data are sent to the server via ZigBee and then it communicates to a smart phone via WI-Fi. In this study, we added divers sensors, designed a protocol which made for transfer several kinds of data and improve mobility for real time monitoring by using smart phones. The system was worked well and the data was transmitted correctly to the smart phone.

• Journal of KSNVE
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• v.9 no.1
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• pp.70-76
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• 1999

This paper presents a pseudo-sensor-output-feedback(PSOF) method for the vibration suppression of the flexible piezoelectric smart structures. This method reduces the modeling errors using pseudo sensors in the output equation formulation. It also reduces computation time in practice. since the output equation does not need the state observer required in the state space equation. Experimental works are performed for the validation of theoretical predictions with the piezoelectric sensor and actuator bonded on the cantilever beam. An algorithm based on the sliding mode control theory is developed and analyzed for the robustness to the modeling errors and parameter uncertainties. This study also discusses the characteristics of the active and semi-active systems.

• Proceedings of the KIEE Conference
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• 2002.07d
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• pp.2132-2134
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• 2002

최근 분산제어시스템 설계시 CAN(Controller Area Network)을 적용하는 연구가 활발히 진행되고 있다. 본 논문에서는 분산제어에 필요한 각종 입출력 데이터를 CAN버스 상에서 송수신할 수 있는 Smart Sensor/Actuator Node를 직접 개발하고, 이를 이용한 실험용 Network를 구축하였다. Sensor Node에서 획득된 외부의 Analog신호를 CAN Bus를 통해 전송한 후, 원격지의 Actuator Node에서 출력하는 Data 송수신 실험을 통해서 설계된 Network와 각 Node의 효율성을 입증하였다.

• Journal of electromagnetic engineering and science
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• v.13 no.4
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• pp.208-213
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• 2013

This paper proposes a tag antenna for radio frequency identification (RFID) food system. The RFID tag antenna is designed and fabricated based on the rectangular loop concept used in the UHF band (Korean and Japanese standards, 916.7-923.5MHz). The proposed tag antenna is composed of a radiation patch, sensor tag chip, temperature sensor, oscillator, and battery. We conjugated matching between the tag antenna and the sensor tag using a U-shaped stub. Details of the proposed tag antenna design and the simulated and measured results are presented and discussed.

• Journal of Sensor Science and Technology
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• v.32 no.6
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• pp.403-411
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• 2023

The shift in the medical paradigm from treatment to prevention and diagnosis has underscored the growing significance of biosensors. Notably, the recent COVID-19 pandemic has spurred the widespread adoption of biosensors for the detection of viral genes and antigens. Consequently, there has been a substantial increase in both the demand for biosensors and the industries associated with their production. Furthermore, biosensors find applications not only in healthcare but also in diverse fields such as environmental monitoring, food quality control, military defense, and industrial processes. In this brief review, we delve into the essential attributes of biosensors, namely sensitivity, selectivity, and stability. We provide an overview of the latest research trends aimed at improving these attributes. Additionally, we introduce recent research cases in which these attributes are being applied both in vivo and in vitro.