• 센서학회지
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• 제25권4호
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• pp.271-274
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• 2016

The reliability and reproducibility of gas sensors are very important for real applications. The influence of nanofiber length and sensing film thickness on the reliability and response of gas sensing characteristics was investigated. For this, the length of $SnO_2$ nanofibers was controlled by tuning ultrasonic treatment and the different thicknesses of sensing films were prepared by manipulating the amount of slurry deposition. The sensor prepared from long nanofibers (length: ${\sim}3.6{\mu}m$) showed the significant fluctuation of gas sensing characteristics when the film becomes thinner than $18{\mu}m$, while that prepared from short nanofibers (length: ${\sim}0.9{\mu}m$) showed reproducible sensor response and resistance regardless of film thickness. Moreover, the shortening of nanofibers enhanced the gas response ~2 times, which can be explained by the increase of chemiresistive fiber-to-fiber contacts. The reproducibility, gas response, and selectivity of $SnO_2$ nanofiber gas sensor could be controlled by tuning nanofiber length, film thickness, and catalyst loading.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
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• pp.387.1-387.1
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• 2014

A new class of temperature-sensing materials is demonstrated along with their integration into transparent and flexible field-effect transistor (FET) temperature sensors with high thermal responsivity, stability, and reproducibility. The novelty of this particular type of temperature sensor is the incorporation of an R-GO/P(VDF-TrFE) nanocomposite channel as a sensing layer that is highly responsive to temperature, and is optically transparent and mechanically flexible. Furthermore, the nanocomposite sensing layer is easily coated onto flexible substrates for the fabrication of transparent and flexible FETs using a simple spin-coating method. The transparent and flexible nanocomposite FETs are capable of detecting an extremely small temperature change as small as $0.1^{\circ}C$ and are highly responsive to human body temperature. Temperature responsivity and optical transmittance of transparent nanocomposite FETs were adjustable and tuneable by changing the thickness and R-GO concentration of the nanocomposite.

• 센서학회지
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• 제26권4호
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• pp.228-234
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• 2017

Gas sensors based on metal-oxide-semiconductors are predominantly used in numerous applications including monitoring indoor air quality and detecting harmful substances such as volatile organic compounds. Nanostructures, e.g., nanoparticles, nanotubes, nanodomes, or nanofibers, have been widely utilized to improve the gas sensing properties of metal-oxide-semiconductors by increasing the effective surface area participating in the surface reaction with target gas molecules. Recently, 1-dimensional (1D) metal oxide nanostructures fabricated using glancing angle deposition (GAD) method with e-beam evaporation have been widely employed to increase the surface-to-volume ratio significantly with large-area uniformity and reproducibility, leading to promising gas sensing properties. Herein, we provide a brief overview of 1D metal oxide nanostructures fabricated using GAD and their gas sensing properties in terms of fabrication methods, morphologies, and additives. Moreover, the gas sensing mechanisms and perspectives are presented.

• Nuclear Engineering and Technology
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• 제52권8호
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• pp.1689-1696
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• 2020

In this study, we developed a fiber-optic humidity sensor (FOHS) system for the monitoring and detection of coolant leakage in nuclear power plants. The FOHS system includes an FOHS, a spectrometer, a halogen white-light source, and a Y-coupler. The FOHS is composed of a humidity-sensing material, a metal tube, a multi-mode plastic optical fiber, and a subminiature version A (SMA) fiber-optic connector. The humidity-sensing material is synthesized from a mixture of polyvinylidene fluoride (PVDF) in dimethyl sulfoxide (DMSO) and hydroxyethyl cellulose (HEC) in distilled water. We measured the optical intensity of the light signals reflected from the FOHS placed inside the humidity chamber with relative humidity (RH) variation from 40 to 95%. We found that the optical intensity of the sensing probe increased linearly with the RH. The reversibility and reproducibility of the FOHS were also evaluated.

• 감성과학
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• 제21권1호
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• pp.35-44
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• 2018

본 연구에서는 센서의 표면적 변화에 따른 입체적 호흡수 센서의 센싱 방식을 제안하고, 직물 기반의 입체적 호흡수 센서의 성능 평가 및 의복에 적용할 수 있는 디자인 방향성을 탐색하고자 한다. 이를 위해 입체적 구조의 차이에 따라 2가지 유형의 입체적 호흡수 센서를 제작하고 더미와 인체 대상으로 연구를 실시하였다. 연구I은 더미 대상 실험으로 센서의 유형 및 호흡 속도의 연구변인에 의해 입체적 호흡수 센서의 측정 가능성을 탐색하였다. 연구II는 7명의 20대 남성을 대상 실험으로 연구I의 연구변인 이외에 3개의 측정 위치별 적합한 유형의 센서를 제안하였다. 입체적 호흡수 센서의 정확도, 재현성, 신뢰도를 평가하기 위해, 의료기기 분야의 대표적 웨어러블 호흡수 센서인 BIOPAC을 사용하여 입체적 호흡수 센서와 동시에 호흡수를 측정하였다. 이상의 연구 결과를 통해 더미 대상으로 입체적 호흡수 센서의 측정 가능성을 탐색하였으며, 인체 대상으로 호흡수를 측정하여 측정 위치별 적합한 유형의 센서를 제안하였다.

• 센서학회지
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• 제25권5호
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• pp.344-348
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• 2016

We developed a 2-channel fiber-optic temperature sensor (FOTS) using a temperature sensing probe, a fiber-optic coupler, transmitting optical fiber, and an optical time domain reflectometer (OTDR). The temperature sensing probe is divided into a sensing probe and a reference probe for accurate thermometry. A sensing probe is composed of a silicon oil, a FC terminator, a brass pipe, and a singlemode optical fiber and the structure of a reference probe is identical with that of the sensing probe excluding a silicon oil. In this study, we measured the modified optical powers of the light signals reflected from the temperature sensing probe placed inside of the water with a thermal variation from 5 to $70^{\circ}C$. Although the optical power of the reference probe was constant regardless of the temperature change, the optical power of the sensing probe decreased linearly as the temperature increased. As experimental results, the FOTS using a subtraction method showed a small difference (i.e., hysteresis) in its response due to heating and cooling. The reversibility and reproducibility of the FOTS were also evaluated.

• Bulletin of the Korean Chemical Society
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• 제7권1호
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• pp.36-38
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• 1986

The Ferricyanide-sensing electrodes were prepared with $Ag_2S\;and\;Ag_3Fe(CN)_6$ (mole ratio 3:1-7:1). The 5:1 $(Ag_2S:Ag_3Fe(CN)_6)$ composition is superior to others in terms of potentiometric response, rapidity of response and reproducibility. Testing was done over the concentration range $10^{-1}M{\sim}10^{-6}M\; Fe(CN)_6^{3-}$ at pH 6.8 with constant ionic strength. The concentration-potential curve was linear and coincided with the Nernstian slope (19.7 mV/decade). Interfering ions were $I^-,\;Br^-,\; SCN^-\;and\;Fe(CN)_6^{4-}$ and the life time of this electrode was 3 weeks. This electrode could be used as the indicator electrode for measuring the ferricyanide and ferrocyanide.

• 센서학회지
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• 제27권2호
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• pp.105-111
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• 2018

In this paper, a torque sensor is designed and fabricated to measure the knee joint torque of a walking assist robot for stroke patients. The torque sensor sensing part was modeled on the link of the part connected to the knee joint motor. The torque capacity of the knee joint was calculated by simulation and the size of the torque sensor sensing part was designed using the finite element method. The torque sensor was fabricated by attaching a strain gauge to the sensing part. Characteristic experiments were conducted to characterize the torque sensor, and the torque sensor was calibrated to utilize it for the control of the walking assist robot. As a result of the characteristics test, the reproducibility error and the nonlinearity error of the torque sensor were 0.03% and 0.04%, respectively. Therefore, it is considered that the developed torque sensor can be used to measure the torque applied to the knee joint when walking on a walking assist robot.

• 센서학회지
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• 제27권1호
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• pp.13-20
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• 2018

Gas sensors based on metal oxide semiconductors are used in numerous applications including monitoring indoor air quality and detecting harmful substances like volatile organic compounds. Nanostructures, for example, nanoparticles, nanotubes, nanodomes, and nanofibers have been widely utilized to improve gas sensing properties of metal oxide semiconductors, and this increases the effective surface area, resulting in participation of more target gas molecules in the surface reaction. In the recent times, 1-dimensional (1D) metal oxide nanostructures fabricated using anodic oxidation have attracted great attention due to their high surface-to-volume ratio with large-area uniformity, reproducibility, and capability of synthesis under ambient air and pressure, leading to cost-effectiveness. Here, we provide a brief overview of 1D metal oxide nanostructures fabricated by anodic oxidation and their gas sensing properties. In addition, recent progress on thin film-based anodic oxidation for application in gas sensors is introduced.

• 대한원격탐사학회지
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• 제37권6_2호
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• pp.1803-1818
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• 2021

기후변화로 인해 가뭄의 발생 빈도가 증가함에 따라 광범위하게 발생하는 가뭄의 상황을 정확하게 판단할 수 있는 모니터링 체계를 갖추는 것이 매우 중요하다. 그러나 지상 관측 기상자료만으로는 한국의 전 지역에 대한 복잡한 가뭄을 모두 파악하기에는 한계가 존재하는 반면, 인공위성 원격탐사자료는 광범위한 지역에서의 가뭄의 공간적 특성을 파악하고 가뭄을 탐지하는 데 효과적으로 이용될 수 있다. 본 연구에서는 남한의 가뭄 식별을 위한 원격탐사자료의 활용 가능성을 분석하고자 하였다. 다양한 측면의 가뭄을 모니터링하기 위해 가뭄에 영향을 미치는 주요 변수인 강수량과 잠재증발산량의 원격탐사 및 지상 관측자료를 수집하였다. 원격탐사자료의 적용성 평가는 관측자료와의 비교를 중심으로 수행하였다. 먼저 원격탐사자료의 적용성과 정확성을 평가하기 위하여 관측자료와의 상관관계를 분석하고, 기상학적 가뭄 모니터링을 위해 강수량과 잠재증발산량을 이용하여 다양한 측면의 가뭄지수들을 산정하였다. 이후 원격탐사자료의 가뭄 모니터링 능력을 평가하기 위해 가뭄지수에 대한 ROC 분석을 적용하여 과거 가뭄 재현성을 확인하였다. 마지막으로 원격탐사자료를 이용한 고해상도의 가뭄 지도를 작성하여 남한의 실제 가뭄에 대한 원격탐사자료의 모니터링 활용 가능성을 평가하였다. 원격탐사자료의 적용을 통해 향후 미 계측 유역을 포함한 남한 전 지역에서 다양하게 발생하는 가뭄 상황을 파악하고 이해할 수 있을 것으로 판단되었다.