• Journal of the Korean Ceramic Society
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• v.34 no.4
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• pp.387-393
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• 1997

In order to apply WO3 thin films to the semiconducting NOx gas sensors as a sensing material, which have been expected to show good electrical properties, such as large sensitivity, rapid responsibility, and high selectivity, the fabrication method and their sensing characteristics were studied. The variations of surface morphologies, crystallographic orientations and crystallinity with the WO3 thin film growing methods thermal evaporation and DC sputtering methods were investigated by using scanning electron microscopy (SEM) and X-ray diffraction(XRD) analysis. As a result of sensitivity (Rgas/Rair) measurements for the 5 ppm NO2 test gas, the sensitivity values were 113 for the sputtered films and 93 for the evaporated films. It was also observed that the recovery rate of a sensing signal after measuring sensitivity was faster in the sputtered films than in the evaporated films.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.04a
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• pp.215-219
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• 1996

We developed a part of hydraulic stroke sensing cylinder for te purpose of position controlbyusing magnetic sensor and evaluated variously its performance its performance. In this paper, for the evaluation of the developed cylinder under various temperature change, thermal control systems are designed and controlled. It is composed of an heater case, temperature sensor, and interface circuits which included SCR(silicon controlled rectifier) for the control of the voltage's phase. To obtain various temperature conditions, the thermal systems are controlled by using Ziegler-Nichols PED tuning method. The thermalcontrol systems are used to experiment to evaluate whether the developed cylinder can obtain a stable output signal for detecting a stroke of the cylinder under the controlled temperature condition.

• Proceedings of the KSRS Conference
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• 2008.10a
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• pp.26-28
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• 2008

Soil moisture plays an important role in the land-atmosphere energy balance because it governs the partitioning of energy through latent heat fluxes or evapotranspiration. From the numerous studies, it is evident that the L-band radiometer is a useful and effective tool to measure soil moisture. The objective of the study is to develop and to verify the soil moisture retrieval algorithms for the L-band radiometer system. Through the radiometer-observed brightness temperature, surface emissivity and reflectivity can be derived, and, hence, soil moisture. We collect field and L-band airborne radiometer data from washita92, SGP97 and SGP99 experiments to assist the development of the retrieval algorithms. Upon launching the satellite L-band radiometer such as ESA-sponsored SMOS (Soil Moisture and Ocean Salinity) mission, the developed algorithms may be used to study and monitor globe soil moisture change.

• Journal of Korea Multimedia Society
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• v.7 no.6
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• pp.767-780
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• 2004

Interaction requires dynamic relationship between objects. In ubiquitous computing environment, interaction between human and the environment is implied. Tactile interaction has so far been less addressed, while tactile sensation should be an important topic in the field of multimedia study. This paper describes development of a novel PVDF (Polyvinylidene Fluoride) dynamic tactile sensor and associated experiments. PVDF dynamic tactile sensors detect touch events applied to the sensor skin by low frequency components of the signal. Rubber skin-covered sensing material was mounted on the bones. Robust performance with low noise was figured out in our robotic experiment. Whereas most conventional sensors are interested in measurement, our dynamic tactile sensor is sensitive to change of state, which could be a key for economic understanding of happenings in the dynamic world. We note that dynamic sensing uses motion as a part of sensing modality We suggest that dynamic sensing be understood in technological terms in the perspective of interactive media and ubiquitous computing.

• Korean Journal of Remote Sensing
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• v.10 no.2
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• pp.63-82
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• 1994

Multitemporal analysis with remotely sensed data is complicated by numerous intervening factors, including atmospheric attenuation and occurrence of clouds that obscure the relationship between ground and satellite observed spectral measurements. A reconstruction system was developed to increase the discrimination capability for imagery that has been modified by residual dffects resulting from imperfect sensing of the target and by atmospheric attenuation of the signal. Utilizing temporal information based on an adaptive timporal filter, it recovers missing measurements resulting from cloud cover and sensor noise and enhances the imagery. The temporal filter effectively tracks a systematic trend in remote sensing data by using a polynomial model. The reconstruction system were applied to the AVHRR data collected over Korean Peninsula. The results show that missing measurements are typically recovered successfully and the temporal trend in vegetation change is exposed clearly in the reconstructed series.

• Current Optics and Photonics
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• v.7 no.2
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• pp.200-206
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• 2023

Near-infrared (NIR) sensing technology using CMOS image sensors is used in many applications, including automobiles, biological inspection, surveillance, and mobile devices. An intuitive way to improve NIR sensitivity is to thicken the light absorption layer (silicon). However, thickened silicon lacks NIR sensitivity and has other disadvantages, such as diminished optical performance (e.g. crosstalk) and difficulty in processing. In this paper, a pixel structure for NIR sensing using a stacked CMOS image sensor is introduced. There are two photodetection layers, a conventional layer and a bottom photodiode, in the stacked CMOS image sensor. The bottom photodiode is used as the NIR absorption layer. Therefore, the suggested pixel structure does not change the thickness of the conventional photodiode. To verify the suggested pixel structure, sensitivity was simulated using an optical simulator. As a result, the sensitivity was improved by a maximum of 130% and 160% at wavelengths of 850 nm and 940 nm, respectively, with a pixel size of 1.2 ㎛. Therefore, the proposed pixel structure is useful for NIR sensing without thickening the silicon.

• Current Optics and Photonics
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• v.8 no.5
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• pp.456-462
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• 2024

We propose a novel fade-free optical fiber interferometric vibration sensor using a simple setup with a 90° optical hybrid. The interferometer consists of all-optical components without the phase modulators and complex demodulation processes that were previously used to compensate for signal fading induced by phase bias change. Fade-free output was successfully obtained by in-phase and quadrature detection with a π/2 phase shifting scheme. Theoretical analysis and measurement results showed that the proposed interferometric vibration sensor operates independently of the phase bias state of interfering waves.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.195-195
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• 2012

Recently, graphene based solution-gated field-effect transistors (SGFETs) have been received a great attention in biochemical sensing applications. Graphene and reduced graphene oxide (RGO) possess various advantages such as high sensitivity, low detection limit, label-free electrical detection, and ease of fabrication due to their 2D nature and large sensing area compared to 1D nanomaterials- based nanobiosensors. Therefore, graphene or RGO -based SGFET is a good potential candidate for sensitive detection of protons (H+ ions) which can be applied as the transducer in various enzymatic or cell-based biosensing applications. However, reports on detection of H+ ions using graphene or RGO based SGFETs have been still limited. According to recent reports, clean graphene grown by CVD or exfoliation is electrochemically insensitive to changes of H+ concentration in solution because its surface does not have terminal functional groups that can sense the chemical potential change induced by varying surface charges of H+ on CVD graphene surface. In this work, we used RGO -SGFETs having oxygen-containing functional groups such as hydroxyl (OH) groups that effectively interact with H+ ions for expectation of increasing pH sensitivity. Additionally, we also investigate RGO based SGFETs for bio-sensing applications. Hydroloytic enzymes were introduced for sensing of biomolecular interaction on the surface of RGO -SGFET in which enzyme and substrate are acetylcholinesterase (AchE) and acetylcholine (Ach), respectively. The increase in H+ generated through enzymatic reaction of hydrolysis of Ach by AchE immobilized on RGO channel in SGFET could be monitored by the change in the drain-source current (Ids).

• Korean Journal of Remote Sensing
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• v.34 no.6_2
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• pp.1155-1163
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• 2018

Recently, much attention has been focused on the change and role of the Arctic region due to climate change. Studies using various platforms are being conducted in the polar regions. Among them, monitoring of Arctic cryosphere information using remote sensing is the most important observational role of various scientific activities. This special issue introduces several studies on polar exploration monitoring in polar research. We hope that this special issue contributes to the sharing of information on the role of polar exploration in remote areas, as well as the identification of the current status of domestic polar exploration and remote environmental exploration. We are also looking forward to the efforts of Korean remote sensing experts to find out the persistent polar exploration field and to increase national support.

• Proceedings of The Korean Society of Agricultural and Forest Meteorology Conference
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• 2019.08a
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• pp.120-121
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• 2019