• 융합보안논문지
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• 제13권4호
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• pp.27-32
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• 2013

본 논문에서는 기저귀에 부착되어 배뇨를 감지한 후 10~20m 이내의 보호자 스마트폰으로 배뇨 발생을 자동으로 알리는 스마트폰형 배뇨알람장치의 구현 기술을 소개한다. 적용된 기술의 특징은 전력 소모 최소화에 있으며 이를 위해 저(低)전력 블루투스 v4.0 기술과 센서 데이터를 수집하지 않는 동안 센서 및 마이크로컨트롤러(micro-controller)를 수면(sleep) 모드로 동작시키는 전력 절감형 프로그램 구동 방식을 적용한다. 배뇨 발생의 정확도를 제고하기 위하여 온/습도 측정 데이터의 절대적인 값을 사용하지 않고 일정 시간 주기로 데이터를 측정하고 이전 값과 현재 값과의 차이를 기반으로 배뇨를 감지하는 방식을 적용한다. 적용 기술을 기반으로 시제품을 구성하고 제품의 성능 시험을 통해 최소 배뇨 검출량 100ml, 검출 정확률 90% 이상, 무선통신 성공률 100%의 성능이 제공됨을 확인한다.

• 센서학회지
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• 제33권3호
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• pp.139-146
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• 2024

Surface-enhanced Raman scattering (SERS) enables the detection of various types of π-conjugated biological and chemical molecules owing to its exceptional sensitivity in obtaining unique spectra, offering nondestructive classification capabilities for target analytes. Herein, we demonstrate an innovative strategy that provides significant machine learning (ML)-enabled predictive SERS platforms through surface-engineered graphene via complementary hybridization with Au nanoparticles (NPs). The hybridized Au NPs/graphene SERS platforms showed exceptional sensitivity (10^-7 M) due to the collaborative strong correlation between the localized electromagnetic effect and the enhanced chemical bonding reactivity. The chemical and physical properties of the demonstrated SERS platform were systematically investigated using microscopy and spectroscopic analysis. Furthermore, an innovative strategy employing ML is proposed to predict various analytes based on a featured Raman spectral database. Using a customized data-preprocessing algorithm, the feature data for ML were extracted from the Raman peak characteristic information, such as intensity, position, and width, from the SERS spectrum data. Additionally, sophisticated evaluations of various types of ML classification models were conducted using k-fold cross-validation (k = 5), showing 99% prediction accuracy.

• 대한화학회지
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• 제53권2호
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• pp.144-151
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• 2009

카드뮴이온 검출을 위한 optode를 triacetylecelluose 막에 있어 dithizone을 고정에 의하여 디자인 되었다. Optode 막이 카드뮴을 포함하는 611 nm 에서 흡수 변화가 가능한 실제시료에 도입 되었을 때 녹색에서 붉은 색으로 색 변화가 일어났다. $Cd^{2+}$ 이온 검출은 검출한계가 0.025 ${\mu}g\;ml^{-1}$ (25 ng $ml^{-1}$)이고 0.3-3 ${\mu}g\;ml^{-1}$ (2.67-26.67 ${\mu}M$)범위에서 가능하였다. Optode의 반응 시간은 $Cd^{2+}$ 이온에 의존하여 15분 안 에서 일어 났다. 다른 간섭종의 효과에 대해 시험되었고 좋은 선택성을 보였다. 제안된 optode를 사용하 여 오염된 토양과 물시료에서 $Cd^{2+}$ 이온의 검출 결과는 잘 확립된 원자흡수법과 동등하게 얻을 수 있었다.

• 한국음향학회지
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• 제24권3호
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• pp.160-165
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• 2005

본 연구에서는 DNA의 고정화 및 DNA 혼성화 반응을 감지할 수 있는 SH형 SAW 센서를 개발하였다. 고정화 및 혼성화 반응에 사용된 탐침 DNA 및 표적 DNA는 상보적 결합이 일어날 수 있는 염기서열을 가진 15-mer의 올리고뉴클레 오티드를 사용하였다. SH형 SAW 센서는 압전 단결정 $36^{\circ}\;YX\;LiTaO_3$를 사용하여 100 MHz로 발진되는 이중 지연선 형태로 제작하였다. 제작된 센서는 Au가 증착된 박막위에 고정화된 탐침 DNA와 표적 DNA와의 혼성화 반응을 시키고 난 후 센서의 주파수 변화를 측정하였으며, DNA 고정화 및 혼성화 반응은 pH 7.4의 PBS 완충용액상에서 수행하였다. 개발된 SH형 SAW센서는 $1.55 {\cal}ng/{\cal}ml/Hz$의 민감도를 가지며, DNA 혼성화 특성에 기인한 질량하중 효과에 따른 안정적인 주파수 변화를 나타내었다.

• KSBB Journal
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• 제22권6호
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• pp.443-446
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• 2007

관상심장질환 바이오마커의 하나인 CRP를 batch형 수정진동자 면역센서에 의하여 다음과 같이 분석하였다. 센서시스템의 작동은 직접결합방식에 의하여 행하였으며 CRP에 대한 항체의 최적 고정화농도는 $50{\mu}g/ml$이었다. 시스템의 반응완충용액으로 0.1 M 인산완충용액 (pH 7.0)을 사용하였고 시스템 작동은 baseline 안정화, 시료첨가 및 측정, 10 mM NaOH에 의한 센서 칩 재생의 순으로 행하였다. 이중로그척도로 표시하였을 때 0.27-106.00 nM 범위의 쥐 유래 CRP에 대하여 센서반응과 직선상의 관계를 이루었으며 센서의 검출한계는 0.53 nM이었고 재사용성도 양호하였다.

• KSBB Journal
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• 제10권2호
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• pp.126-130
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• 1995

초산발효 중 에탄올 농도를 On-line으로 측정하기 위해 막가스 센서를 개발하였다. 에탄올이 함유된 발효액은 실리콘막을 통해 투과되고 Carrier gas로 사용된 Synthetic air에 의해 운반되어 반도체형 가 스센서에 감지되도록 설계하였다. 이 때 실리콘막의 두께가 O.5mm이고 Carrier gas의 유속이 20ml/mim이었을 때 막가스 센서의 감도가 가장 높았다. 막가스센셔의 저항치는 측정하고자 하는 에탄올 농 도에 따라 변하였고 이 저항치는 전위차로 변환되어 출력되었다. 제작된 막가스센서의 Calibration CUf ve를 작성하였고 실제로 조업 중인 초산 발효조의 발효액 중 에단올 농도의 On-line 측정이 가능하였 으며 이를 Gas chromatography에 의한 분석치와 비교한 결과 에단올 농도가 $0∼70g/\ell$의 범위에서 서로 상관관계를 나타내어 이러한 막가스센서가 초산발효와 같은 여러 생물공정의 모니터링과 제어에 이용이 가능함을 확인하였다.

• Safety and Health at Work
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• 제10권4호
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• pp.452-460
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• 2019

Background: Monitoring and control of PM_2.5 are being recognized as key to address health issues attributed to PM_2.5. Availability of low-cost PM_2.5 sensors made it possible to introduce a number of portable PM_2.5 monitors based on light scattering to the consumer market at an affordable price. Accuracy of light scatteringe-based PM_2.5 monitors significantly depends on the method of calibration. Static calibration curve is used as the most popular calibration method for low-cost PM_2.5 sensors particularly because of ease of application. Drawback in this approach is, however, the lack of accuracy. Methods: This study discussed the calibration of a low-cost PM_2.5-monitoring device (PMD) to improve the accuracy and reliability for practical use. The proposed method is based on construction of the PM_2.5 sensor network using Message Queuing Telemetry Transport (MQTT) protocol and web query of reference measurement data available at government-authorized PM monitoring station (GAMS) in the republic of Korea. Four machine learning (ML) algorithms such as support vector machine, k-nearest neighbors, random forest, and extreme gradient boosting were used as regression models to calibrate the PMD measurements of PM_2.5. Performance of each ML algorithm was evaluated using stratified K-fold cross-validation, and a linear regression model was used as a reference. Results: Based on the performance of ML algorithms used, regression of the output of the PMD to PM_2.5 concentrations data available from the GAMS through web query was effective. The extreme gradient boosting algorithm showed the best performance with a mean coefficient of determination (R²) of 0.78 and standard error of 5.0 ㎍/㎥, corresponding to 8% increase in R² and 12% decrease in root mean square error in comparison with the linear regression model. Minimum 100 hours of calibration period was found required to calibrate the PMD to its full capacity. Calibration method proposed poses a limitation on the location of the PMD being in the vicinity of the GAMS. As the number of the PMD participating in the sensor network increases, however, calibrated PMDs can be used as reference devices to nearby PMDs that require calibration, forming a calibration chain through MQTT protocol. Conclusions: Calibration of a low-cost PMD, which is based on construction of PM_2.5 sensor network using MQTT protocol and web query of reference measurement data available at a GAMS, significantly improves the accuracy and reliability of a PMD, thereby making practical use of the low-cost PMD possible.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 하계학술대회 논문집
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• pp.223-223
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• 2009

In this paper, designed and simulated Power Splitter (PS) integrated Mach-Zehnder interferometer (MZI) based planar type optical waveguide devices (which is called here a PS-MZI). The PS-MZI optical waveguide sensor was preceded by a Y-junction, which splits the input power between the sensor, and a reference branch, to minimize the effect of optical power variations. The PS-MZI optical waveguide sensor induced changing phases of the incident beam, which had fallen upon the waveguide through computer simulation, according to the small changes in the index of refraction, thus beam intensity was changed. The waveguide were optimized at a wavelength of 1550 nm and fabricated according to the design rule of 0.45 delta%, which is the difference of refractive index between the core and clad. The fabrication of PS-MZI optical waveguide sensor was performed by a conventional planar lightwave circuit (PLC) fabrication process. The PS-MZI optical waveguide that was fabricated to be applied as a biosensor revealed a low insertion loss and a low polarization-dependent loss. After having etched the over-clad at the sensor part in the MZI optical waveguide that was fabricated, Ti deposition was made on the adhesion layer, and then Au thin-film deposition was carried out thereon. In addition, its optical properties were measured by having changed the index of refraction oil at the sensing part of the MZI. To apply the planar type PS-MZI optical waveguide as a biosensor, a detection test for Staphylococcus aureus was conducted according to changes in concentration, having adopted Ti-alkoxide as ligand. The detection result of the S. aureus by the PS-MZI optical waveguide sensor was possible to the level of $10^1$ CFU/ml.

• Journal of information and communication convergence engineering
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• 제13권3호
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• pp.152-158
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• 2015

We consider the problem of designing independently operating local quantizers at nodes in distributed estimation systems, where many spatially distributed sensor nodes measure a parameter of interest, quantize these measurements, and send the quantized data to a fusion node, which conducts the parameter estimation. Motivated by the discussion that the estimation accuracy can be improved by using the quantized data with a high probability of occurrence, we propose an iterative algorithm with a simple design rule that produces quantizers by searching boundary values with an increased likelihood. We prove that this design rule generates a considerably reduced interval for finding the next boundary values, yielding a low design complexity. We demonstrate through extensive simulations that the proposed algorithm achieves a significant performance gain with respect to traditional quantizer designs. A comparison with the recently published novel algorithms further illustrates the benefit of the proposed technique in terms of performance and design complexity.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1988년도 전기.전자공학 학술대회 논문집
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• pp.356-359
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• 1988

An FET type urea sensing device has been developed using the ISFET and platinum reference electrode and by employing the differential amplification. The performance characteristics of the fabricated sensor show a good linearity in the urea concentration range of $5{\times}10^{-5}$ to $10^{-3}$g/ml and a stable response.