• 한국인터넷방송통신학회논문지
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• 제17권5호
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• pp.231-237
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• 2017

본 논문은 온도와 빛, 수분의 량을 탐지하여 자동으로 습도와 조도를 채워주는 스마트 화분을 만든 사례를 소개한다. 화분을 담는 용기는 3D 프린터로 제작하고, 용기의 내부에는 Wi-Fi가 내장된 NodeMCU 마이크로컨트롤러를 장착하였다. 온도와 습도, 조도를 감지하는 센서와, 펌프를 NodeMCU에 연결하고 제어 프로그램을 작성하여 NodeMCU 스스로 습도와 조도를 조절하도록 하였다. 또한 subscribe-publish 모델로 작동하는 MQTT 서버를 구축하고, NodeMCU와 본 연구에서 개발한 안드로이드 앱이 정보를 교환하도록 하였다. 안드로이드 앱의 사용자는 식물에게 적절한 온도, 습도, 조도를 스마트 화분에게 전달하고, 스마트 화분으로부터 현재 온도, 습도, 조도 정보를 모니터링 할 수 있게 하였다.

• ETRI Journal
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• 제38권3호
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• pp.551-559
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• 2016

In this paper, we propose a hybrid sensor calibration scheme for mobile crowdsensing applications. As the number of newly produced mobile devices containing embedded sensors continues to rise, the potential to use mobile devices as a sensor data source increases. However, because mobile device sensors are generally of a lower performance and cost than dedicated sensors, sensor calibration is crucial. To enable more accurate measurements of natural phenomena through the use of mobile device sensors, we propose a hybrid sensor calibration scheme for such sensors; the scheme makes use of mobile device sensors and existing sensing infrastructure, such as weather stations, to obtain dense data. Simulation results show that the proposed scheme supports low mean square errors. As a practical application of our proposed scheme, we built a temperature map of a city using six mobile phone sensors and six reference sensors. Thanks to the mobility of the sensors and the proposed scheme, our map presents more detailed information than infrastructure-based measurements.

• 지구물리
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• 제7권4호
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• pp.305-311
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• 2004

사면 붕괴 및 활동 발생지점을 중점대상으로 보강재의 응력 측정 및 변위 수반여부를 판단하기 위하여 경사계, 변형율계 및 간극수압계 등의 계측기를 설치하였으며, 이로부터 사면의 실시간 건전도 모니터링의 가능성을 보여 주었다. 본 연구에서는 현장계측을 통하여 사면의 거동, 억지말뚝의 효과 및 활동면에서의 응력분포간의 관계를 밝히고자 하였다.

• 대한임베디드공학회논문지
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• 제2권2호
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• pp.82-94
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• 2007

Wireless sensor networking technology is one of the basic infrastructures for ubiquitous environment. It enables us to gather various sensory data such as temperature, humidity, gas leakage, and speed from the remote sensor devices. To support these networking functions, IEEE WPAN working group makes standards for PHY and MAC, while ZigBee Alliance defines the standards for the network, security, and applications. The low-rate WPAN was emerged to have the characteristics of network resilience, low cost, and low power consumption. It has a broad range of applications including, but not limit to industrial control and monitoring, home automation, disaster forecast and monitoring, health care. In order to provide more intelligent and robust services, users want voice-based solutions to accommodate to low-rate WPAN. In this paper, we have evaluated voice quality of an IEEE 802.15.4 standard compliant voice node. Specifically, it includes the design of a voice node and experiments based on the prediction of voice quality using the E-model suggested by ITU-T G.107, and the network communication mechanisms considering beacon-enabled and nonbeacon-enabled networks for real-time voice communications.

• Smart Structures and Systems
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• 제19권3호
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• pp.269-277
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• 2017

Recently, there has been significant interest in structural health monitoring for civil engineering applications. In this research, a specially designed tendon, proposed by embedding FBG sensors into the center king cable of a 7-wire strand tendon, was applied for long-term health monitoring of tensile forces on a ground anchor. To make temperature independent sensors, the effective temperature compensation of FBG sensors must be considered. The temperature sensitivity coefficient ${\beta}^{\prime}$ of the FBG sensors embedded tendon was successfully determined to be $2.0{\times}10^{-5}^{\circ}C^{-1}$ through calibrated tests in both a model rock body and a laboratory heat chamber. Furthermore, the obtained result for ${\beta}^{\prime}$ was formally verified through the ground temperature measurement test, expectedly. As a result, the ground temperature measured by a thermometer showed good agreement compared to that measured by the proposed FBG sensor, which was calibrated considering to the temperature sensitivity coefficient ${\beta}^{\prime}$. Finally, four prototype ground anchors including two tension ground anchors and two compression ground anchors made by replacing a tendon with the proposed smart tendon were installed into an actual slope at the Yeosu site. Tensile forces, after temperature compensation was taken into account using the verified temperature sensitivity coefficient ${\beta}^{\prime}$ and ground temperature obtained from the Korean Meteorological Administration (KMA) have been monitored for over one year, and the results were very consistent to those measured from the load cell, interestingly.

• 전기전자학회논문지
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• 제24권2호
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• pp.673-676
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• 2020

본 논문에서는 IT 기술을 접목한 초저온 순환 냉각 방식의 전신 관리 시스템을 제안한다. 제안하는 시스템은 다음과 같은 특징들을 가진다. 첫 번째로 초저온으로 냉각된 질소가스를 관리기 내부에서 순환시킴으로서 유지비용을 최소화한다. 두 번째로 온도센서와 산소농도센서로 측정된 정보를 기초로 질소가스를 공급하여 안전한 초저온 전신관리를 제공한다. 세 번째로 사용자의 신장을 입력한 후에 전자동 리프트를 이용하여 제어 가능한 편리한 초저온 전신관리를 제공한다. 네 번째로 접근이 쉽고 조작이 편리한 GUI 및 전신관리 시스템 운영을 위한 관리자 전용 웹 프로그램의 GUI를 제공한다. 제안된 시스템의 성능을 평가하기 위하여 공인시험기관에서 실험한 결과는 온도센서 정확도는 세계 최고 수준인 ±5%의 범위에서 측정이 되었고, 전신관리 온도범위는 세계 최고 수준(-110℃ ~ -140℃)보다 넓은 -110℃ ~ -150℃의 범위가 측정되었다. 또한, 습도는 세계 최고 수준인 40% 미만으로 측정이 되었고, 산소농도도 세계 최고 수준인 18% 이상으로 측정되었다. 따라서 본 본문에서 제안한 IT 기술을 접목한 초저온 순환 냉각 방식의 전신 관리 시스템의 성능이 세계 최고 수준과 동일한 결과를 산출하였기 때문에 그 효용성이 입증되었다.

• 한국컴퓨터정보학회논문지
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• 제11권4호
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• pp.299-304
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• 2006

산업현장의 기계장치나 실내 외 그리고 해양 등과 같은 주위 환경의 데이터를 원거리의 중앙 컴퓨터에 전송하여 그 상태를 확인하여 해석하고, 해석된 데이터를 바탕으로 이상 유무 등을 판별하여 시스템의 최적 동작을 위한 시스템 명령 등을 Network나 유 무선 통신을 이용하여 전달하는 온-라인 모니터링 시스템이다. 본 연구는 온-라인 모니터링 시스템을 개발하기 위하여 염산 수조의 온도를 원격지의 중앙 컴퓨터에서 제어하는 시스템으로써 모니터링부 무선송신부, 온도콘트롤부로 이루어진 실험 장치를 구성하였다. 본 시스템을 응용하면 재난 재해방지 시스템, 경보 시스템과 같은 USN(Ubiquitous Sensor Network)시스템에 적용이 가능하다.

• 대한임베디드공학회논문지
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• 제3권3호
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• pp.136-142
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• 2008

Mobile robots can offer services like intelligent monitoring in an indoor environment using network connection with remote users. In this paper, we designed and developed a networked security robot system with various sensors, such as flame detector, gas detector, sound monitoring module, and temperature sensor, etc. The robot can be accessed through a web service and the user can check the status of the environment. Using ADAMS software, we defined the motor specification for a worst-case condition of climbing over a obstacle. We applied the robot system in monitoring office condition.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2000년도 추계학술발표대회 논문집
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• pp.238-244
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• 2000

FBGs have been extensively used as strain sensors or temperature sensors in a variety of applications related to composites because of embedding ability, small size and multiplexing capability. We inspected embedding environments inside composites with optical fiber by microscope analysis and birefringence characteristics of FBG embedded into textile composite laminate by cure monitoring using a high power WSFL. The cure monitoring of the cases with the striped FBG and the recoated FBG provided comprehensive understandings about the birefringence effect induced by the transverse stress. And these results allowed to consider a recoating method as an important tool to relieve birefringence.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 1999년도 추계학술발표대회 논문집
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• pp.251-257
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• 1999

Smart structure that contains sensors, which are either embedded in a composite material or attached to a structure, is currently receiving considerable attention. Fiber Bragg grating sensor, one of the optical fiber sensors, has been widely used to sense strain and temperature for smart structures since both parameters change the resonant frequency of the grating. In this paper, according to the various heating and cooling conditions the thermal behavior of unidirectional composite material was monitored by embedding the fiber Bragg grating sensors in the longitudinal and transverse directions of unidirectional composites. The thermal behavior of unidirectional composite material was monitored for various heating and cooling rates and applied pressure. It was found that the thermal behavior was unaffected by pressure variations and heating and cooling rates applied to the composites. The thermal strains were measured by considering the shift in Bragg wavelength that was generated by the thermal expansion of composite specimen. The longitudinal and transverse C.T.E.'s were also obtained from the corresponding temperature-thermal strain curves.