• 한국인터넷방송통신학회논문지
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• 제17권2호
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• pp.119-126
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• 2017

TCP/IP 표준을 개발하는 IETF의 상위 기구인 IAB는 작은 사물에도 TCP/IP protocol stack을 붙이기로 결정했다. 이는 하나의 작은 사물도 하나의 통신 노드로 인정하여, 이를 다섯 개의 전 계층이 올라간 스마트 오브젝트로 확장하겠다는 상징적인 의미를 가진다. 이러한 배경 아래서 등장한 것이 웹을 기반으로 사물 간 지능적으로 네트워크를 구성해 통신하는 IoT/WoT이다. CoAP는 제한된 환경 내에서 사용할 수 있는 프로토콜로 사물이 인터넷에 연결될 것을 예상하여 만든 표준 규약이다. 이에 따라 본 논문에서는 CoAP 네트워크가 구축된 환경에서 CoAP와 연결되어 관련 사물들의 데이터를 수집하며 관리할 수 있는 Middleware API를 제안하고자 한다.

• Journal of Magnetics
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• 제18권2호
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• pp.159-162
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• 2013

We present how to optimize the operation condition including frequency of the orthogonal fluxgate sensor in this paper. The orthogonal fluxgate sensor was fabricated with a Co-based amorphous wire with 10 mm long and 100 ${\mu}m$ in the diameter and a 270-turn pickup coil wound on the amorphous wire. In order to investigate the frequency dependence of the sensitivity, output spectra of the sensor which was connected by using a coaxial cable with various lengths of 0.5-5 m were measured with a RF lock-in amplifier. The maximum sensitivities were obtained at different frequencies according to coaxial cable lengths. It was found that the optimal operation frequencies, at which maximum sensitivities were appeared, were almost identical to the frequencies of impedance resonance. The maximum sensitivity and optimal operation frequency were 1.1 V/Oe (${\approx}$ 11000 V/T) and 1.25 MHz respectively.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2021년도 춘계학술대회
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• pp.285-286
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• 2021

최근 IoT(Internet of Things) 기술의 발전으로 스마트화 기술이 농업, 축산업, 수산업 분야로 확장되어 스마트화가 진행되고 있다. 이러한 스마트화 기술은 현장의 데이터를 어떻게 계측하여 관리 시스템으로 전송하는가가 무엇보다 중요하다. 현재 스마트팜 및 기타 축사 및 양식장 구축에 활용되는 센서는 온도, 습도, CO 가스, CO2, 수소(Hydrogen), O2 등 다양한 센서를 통하여 스마트팜 및 기타 환격을 계측하고 모니터링하고 있다. 이러한 센서들과 스마트팜을 제어하고 관리하는 HMI(Human Machine Interface) 모듈과의 통신방식은 아직 까지는 RS-485 기반의 모드버스(modbus-RTU) 방식을 주로 활용하고 있다. 본 논문에서는 스마트팜 구축에 필요한 센서 데이터를 HMI 모듈에서 관리할 수 있도록 RS-485 기반의 모드버스 방식을 통하여 데이터를 관리할 수 있도록 다양한 센서 모듈을 연결할 수 있도록 HMI용 MCU 모듈을 설계하고자 한다.

• 센서학회지
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• 제33권3호
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• pp.179-184
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• 2024

In the car industry, welding is a fundamental linking technique used for joining components, such as steel, molds, and automobile parts. However, accurate inspection is required to test the reliability of the welding components. In this study, we investigate the detection of weld beads using 2D image processing in an automatic recognition system. The sample image is obtained using a 2D vision camera embedded in a lighting system, from where a portion of the bead is successfully extracted after image processing. In this process, the soot removal algorithm plays an important role in accurate weld bead detection, and adopts adaptive local gamma correction and gray color coordinates. Using this automatic recognition system, geometric parameters of the weld bead, such as its length, width, angle, and defect size can also be defined. Finally, on comparing the obtained data with the industrial standards, we can determine whether the weld bead is at an acceptable level or not.

• 한국재료학회지
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• 제33권5호
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• pp.195-204
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• 2023

Micro-electronic gas sensor devices were developed for the detection of carbon monoxide (CO), nitrogen oxides (NO_x), ammonia (NH₃), and formaldehyde (HCHO), as well as binary mixed-gas systems. Four gas sensing materials for different target gases, Pd-SnO₂ for CO, In₂O₃ for NO_x, Ru-WO₃ for NH₃, and SnO₂-ZnO for HCHO, were synthesized using a sol-gel method, and sensor devices were then fabricated using a micro sensor platform. The gas sensing behavior and sensor response to the gas mixture were examined for six mixed gas systems using the experimental data in MEMS gas sensor arrays in sole gases and their mixtures. The gas sensing behavior with the mixed gas system suggests that specific adsorption and selective activation of the adsorption sites might occur in gas mixtures, and allow selectivity for the adsorption of a particular gas. The careful pattern recognition of sensing data obtained by the sensor array made it possible to distinguish a gas species from a gas mixture and to measure its concentration.

• 센서학회지
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• 제4권1호
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• pp.9-14
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• 1995

자기저항 효과를 이용한 저자장 자기센서를 제작하기 위하여 슬라이드 유리 기판위에 Ni-Co(0.7Ni-0.3Co) 합금을 $600\;{\AA}$ 두께로 진공증착 하였다. 증착된 박막을 bridge 구조의 격자무늬로 식각하는 과정에서 4개의 bridge arm을 주축과 $45^{\circ}$로 배열하고 그 면적율을 67%로 증대시켰다. 제작된 센서는 자장범위 ${\pm}0.5mT$에서 직선성이 양호하였으며 백색잡음은 0.2nV 이었고 전압감도는 7.6 $nV/{\mu}T$ 이었다.

• 상하수도학회지
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• 제29권3호
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• pp.325-335
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• 2015

Concerns about water quality in the Nakdong River have been raised because the Nakdong River will change from a lotic environment to a lentic environmental due to the installation of eight weirs to be constructed as part of the Four Major Rivers Restoration Project. The rapid urbanization and industrialization of the middle and the lower reaches of Nakdong River causes the indiscreet discharge of uncleanly living sewage and industrial wastewater. And the water quality of lower reaches of Nakdong River is getting seriously worse. Owing to the water shortage of Nakdong River and the closing of reaches because of the estuary dyke in the dry season, the velocity of a moving fluid is almost accumulated under 0.03m/sec. Then a pollutant is piled up on the bottom of the river. Polluted sediment is formed and nutrition level of water is increased more and more. The eutrophication state propagated to dark brown or green from eutrophication often comes out. Therefore in this study, we measured Chl. a of chlorophyll sensor (YSI6600V2) and aceton extraction through field observation in the Nakdong River and Samrangjin. And we evaluated the reliability of chlorophyll sensor. In correlation analysis between chlorophyll sensor and aceton extraction, it shows high relation in general. And it also shows high relation among the chlorophyll sensor and aceton extraction of the dominant diatom (Skeletonema costatum), Dinophyta (Prorocentrum minimum) in the Nakdong River estuary by laboratory analysis results.

• 센서학회지
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• 제10권5호
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• pp.279-285
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• 2001

본 논문에서는 동맥혈중 이산화탄소 분압을 실시간으로 추정하는 capnograph 시스템에 상용되는 대부분 NDIR 흡수식(non-dispersive infrared absorption) 광챔버와 신호처리회로를 설계 및 구현하였다. 광챔버 설계시 일반 정상인의 capnogram을 주파수 분석하여 적합한 광쵸핑 주파수를 결정한 뒤, 이에 근거하여 시간응답을 고려한 광챔버를 설계하였으며, 열잡음에 대한 영향을 줄이기 위해 2광원 1센서 방식의 $CO_2$ 농도 신호처리회로를 구현하였다. 구현된 광챔버에 대한 가스배출시간을 조사하였으며 신호처리회로를 외부 온도 변화 실험에 적용한 결과 2광원 1센서 방식이 안정된 출력 신호를 얻을 수 있음을 확인하였고, 실제 사람의 호흡에 대한 실험결과 정상적인 capnogram 형태의 $CO_2$ 농도 변화 곡선을 보였다.

• 한국세라믹학회지
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• 제20권2호
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• pp.93-98
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• 1983

The sensitivity characteristics of $SnO_2$-based gas sensor prepared by sintering method have been studied at the presence of CO and Propane gas. Samples mixed with 1wt% $La_2O_3$ and 1wt% $PdCl_2$ showed highest sensitivity to CO and propane gas at 250$^{\circ}$C but the addition of $CeO_2$ did not enhance the sensitivity. For slectivity for gas a $SnO_2-La_2O_3$ (1wt%) sample without $PdCl_2$ showed better results. A sample sintered sintered at 115$0^{\circ}C$ has shown the optimum condition in sensitivity and electroding

• 한국표면공학회지
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• 제49권4호
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• pp.382-388
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• 2016

NiO nanoparticles were synthesized by hydrothermal method for the application to ethanol gas sensor. They were composited with $Co_3O_4$ nanoparticles to improve the sensitivity to ethanol gas. Scanning electron microscopy revealed that the synthesized NiO nanoparticles were plate-shaped with the approximate size and thickness of 60 - 120 nm and 20 nm, respectively. On the other hand, $Co_3O_4$ nanoparticles mixed with NiO was observed to be spherical with the size range of 30 - 50 nm. The sensitivities of NiO sensors composited with $Co_3O_4$ nanoparticles at an optimal ratio of 8 : 2 were enhanced to approximately 1.44 - 1.79 times as high as those of as-synthesized NiO sensors for the ethanol concentration of 10 - 200 ppm at $200^{\circ}C$. The mechanism of the improved ethanol gas sensing of the NiO sensors composited with $Co_3O_4$ nanoparticles was discussed.