• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.436-436
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• 2014

본 연구에서는 전 세계적으로 활발히 연구되고 있는 나노바이오센서 분야 중 가장 주목을 받고 있는 LSPR 원리를 이용한 바이오센서를 제작하였다. 금속 나노입자의 국소 표면 플라즈몬 공명현상에 의한 주위환경에 민감하게 반응하는 특성은 고감도 광학형 바이오센서, 화학물질 검출 센서등에 응용된다. 특히 금 나노막대와 같은 1차 나노구조물은 나노막대의 주변 환경 변화에 따라 뚜렷한 플라즈몬 흡수 밴드 변화를 나타냄으로 센서로 적용 했을 때 고감도의 측정이 가능하다. 본 연구에서는 다공성인 알루미늄 양극산화 박막 주형틀을 이용하여 다양한 종횡비를 가지는 금 나노막대를 합성하고, 나노막대 어레이 형태의 박막을 제작하였다. 금 나노막대의 합성은 알루미늄 양극산화막을 사용한 주형제조 방법(template method)을 사용하는 전기화학 증착법을 사용하였다. 우선 부도체인 알루미늄 양극 산화막의 한쪽면을 열증착 장비를 사용하여 금을 증착하여 작업 전극(working electrode)을 형성하였다. 백금 선(platinum wire)을 보조 전극(counter electrode)으로 사용하고 Ag/AgCl 전극을 기준 전극(reference electrode)으로 사용하여 삼전극계(three-electrode system)를 형성하였으며, 금 도금 용액(orotemp 24 gold plating solution, TECHNIC INC.)을 사용하여, 800 mV 전압에서 금 나노 막대를 합성하였다. 금 나노막대의 길이는 테플론 챔버를 통과한 전하량 또는 전기 증착 시간에 비례하여 결정된다. 금 나노막대를 성장시킨 알루미늄 양극산화막을 실리콘 웨이퍼에 은 페이스트를 사용하여 고정시킨 후 수산화나트륨 (NaOH)용액을 사용하여 알루미늄 양극산화막을 녹여내어 수직방향으로 정렬되어 있는 나노 막대 어레이 박막을 제조 하였다. 또한 제작된 금 나노막대 어레이의 광학적 특성을 평가하였다. 본 연구에서와 같이 나노막대를 직경방향으로 측정할 경우, 직경방향의 transverse mode만 측정된다. 금 나노 막대가 알루미늄 양극산화막 안에 포함된 상태로 측정된 금 나노로드 어레이 박막의 광 스펙트럼 분포는 금 나노막대의 가시광영역에서의 흡수 스펙트럼을 측정하였을시 직경 및 길이에 따라 transverse mode의 ${\lambda}$ max (최대 흡광)의 위치가 변화됨을 나타낸다. 실험 결과를 바탕으로 나노막대의 종횡비가 증가함에 따라 흡수 스펙트럼의 transverse mode ${\lambda}$ max가 미약하게 단파장 영역으로 이동하는 것을 확인할 수 있다. 이러한 결과는 원기둥 형태의 금 나노막대의 흡수 스펙트럼에 대한 이론적인 예측과 부합한다. 바이오센서로의 적용 가능성을 확인하기 위하여 자기조립단분자막을 형성하여 항체를 고정하고 CRP에 대한 응답특성을 평가하였다. CRP 항원-항체의 면역반응에 대한 실험 결과 CRP 항원의 농도가 증가함에 따라 넓은 측정범위에서 선형적으로 흡광도가 증가하는 결과를 나타내었으며, CRP 10 fg/ml의 농도까지 검출할 수 있었다. 센서의 선택성을 확인하기 위하여 감지하고자하는 대상물질이 아닌 Tn T 항원을 감지막에 반응시켜 흡광도 변화를 분석하였다. 결과적으로 제작된 센서칩은 선택성을 가지고 측정하고자하는 물질에만 반응함을 확인하였다. 이러한 결과는 다양한 직경을 사용한 부가적인 LSPR현상의 연구에 활용될 수 있을 것이다.

• Journal of Sensor Science and Technology
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• v.6 no.5
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• pp.346-355
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• 1997

In this paper, the analyses of the stress disturibution and frequency characteristics of silicon microstructures for an accelerometer were performed using the general purpose finite element simulation program, ANSYS. From the analyses, we determined the parameter values of a new 6-beam piezoresistive accelerometer applicable to the accelerometer's specification in airbag system of automobile. Then, the mass paddle radius, beam length, beam width, and beam thickness of the designed accelerometer were$500{\mu}m$, $350{\mu}m$, $100{\mu}m$, and $5{\mu}m$, respectively and two different seismic masses with 0.4 mg and 0.8 mg were defined on the same sensor structure. The designed 6- beam accelerometers were fabricated on the selectively diffused (111)-oriented $n/n^{+}/n$ silicon substrates and the characteristics of the fabricated accelerometers were investigated. Then, we used a micromachining technique using porous silicon etching method for the formation of the micromechanical structure of the accelerometer.

• Journal of the Korea Society for Simulation
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• v.18 no.3
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• pp.47-59
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• 2009

Due to the application-specific nature of wireless sensor networks, the sensitivity to such a requirement as data reporting latency may vary depending on the type of applications, thus requiring application-specific algorithm and protocol design paradigms which help us to maximize energy conservation and thus the network lifetime. In this paper, we propose a novel delay-adaptive sensor scheduling scheme for energy-saving data gathering which is based on a two phase clustering (TPC). The ultimate goal is to extend the network lifetime by providing sensors with high adaptability to the application-dependent and time-varying delay requirements. The TPC requests sensors to construct two types of links: direct and relay links. The direct links are used for control and forwarding time critical sensed data. On the other hand, the relay links are used only for data forwarding based on the user delay constraints, thus allowing the sensors to opportunistically use the most energy-saving links and forming a multi-hop path. Simulation results demonstrate that cluster-based delay-adaptive data gathering strategy (CD-DGS) saves a significant amount of energy for dense sensor networks by adapting to the user delay constraints.

• Journal of Internet Computing and Services
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• v.10 no.3
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• pp.35-49
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• 2009

In electronic warfare settings, battlefield helicopters identify various threats based upon threat data, which are acquired using their multi-sensors of aircraft survivability equipment (ASE). To continually function despite of potential threats and successfully execute their missions, the battlefield helicopters have to repeatedly report threats in simulated battlefield situations. Toward this ends, the paper presents threat unification using multi-sensor simulator and its implementation. The simulator consists of (1) threat attributes generator, which models threats against battlefield helicopters and defines their specific attributes, (2) threat data generator, which generates threats, being similar to real ones, using normal, uniform, and exponential distributions, and (3) graphic display for threat analysis and unification, which shows unified threat information, for example, threat angle and its level. We implement a multi-sensor threat simulator that can be repeatedly operable in various simulated battlefield settings. Further, we report experimental results that, in addition to tangibly modeling the threats to battlefield helicopters, test the capabilities of threat unification using our simulator.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.3
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• pp.217-225
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• 2003

In this paper, in order to investigate the near field distribution characteristic of the Loop Antenna we simulated and measured the near field of a Loop Antenna using optical electric-field sensor in a large Chamber(8.5 m x 7 m x 7 m). The simulation methods were used MoM for frequency domain and FDTD for time domain. From the analysis results, it can be seen that the simulation and measurement results are very aggregated, and the optical electric-field sensor is a certificate of validity. In frequency domain, in case of the optical sensor with vertical polarization is located above the near vertical line of the Loop Antenna the signal strength level is more 15 ㏈ than with horizontal polarization. But in case of the optical sensor located above horizontal line of the Loop Antenna, signal strength level is not different. And, in the time domain, although input signal is positive, in the case of the optical sensor with vertical polarization is located above horizontal line of the Loop Antenna, it can be seen that the received pulse shape is negative.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.15 no.12
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• pp.2511-2520
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• 2011

This paper describes the parameter adjustment method of fuzzy membership function to improve the performance of multi-sensor fusion system using adaptive fuzzy-Kalman filter and cross-validation. The adaptive fuzzy-Kanlman filter has two input parameters, variation of accelerometer measurements and residual error of Kalman filter. The filter estimates system noise R and measurement noise Q, then changes the Kalman gain. To evaluate proposed adaptive fuzzy-Kalman filter, we make the two-axis AHRS(Attitude Heading Reference System) using fusion of an accelerometer and a gyro sensor. Then we verified its performance by comparing to NAV420CA-100 to be used in various fields of airborne, marine and land applications.

• Journal of the Korean Institute of Gas
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• v.12 no.4
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• pp.63-68
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• 2008

This paper describes about the simulation and the experimental results of optical cavity with curved mirror surface and vertical mirror surface to improve the light intensity and efficiency of the optical sensors. When we use the vertical mirror surface, the distribution of light reached to the filter surface of detector shows an elliptical shape. Whereas, the curved mirror surface focuses the light into circular shape. Therefore, due to focusing effects in case of using curved mirror surface, the light intensity per unit area has been improved. Consequently, the output voltage of gas sensor has been expected to increase. Based upon the simulation, the experiment of gas sensor has been conducted with $CO_2$ gas from 0ppm to 2,500 ppm at 250 ppm step and $25^{\circ}C$, 45%R.H. ambient. The output voltage of gas sensor that has a curved mirror surface increases approximately 200 mV than that of vertical mirror surface.

• Journal of the Korean Geotechnical Society
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• v.16 no.4
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• pp.201-208
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• 2000

Axial load distribution in model piles was measured by fiber Bragg Grating(FBG) sensor to investigate a possibility of analyzing the load transfer mechanism by Fiber Optic sensor system. Since FBGs of different wave lengths can be multiplexed in an optical fiber, the installation of sensor system and the measurement of strains are relatively simple, compared with consisting strain gages. In this study, FBG sensors and electric strain gages were embedded in the same piles and the distributions of load transfer by two sensor systems were measured. It was observed from the test results that the variations of axial load by both systems showed insignificant difference and that the measurements by FBG were smoother than those by strain gage. Under the environments of laboratory testing, survival rate of embedded FBG system was higher than that of strain gage. Therefore, it was concluded that the use of FBG sensor has a great potential for the measurement of load transfer for pile foundation.

• Journal of Sensor Science and Technology
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• v.8 no.6
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• pp.461-468
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• 1999

In this paper, we have implemented a gas recognition system for classification and identification of explosive gases such as methane, propane, and butane using a sensor array and an artificial neural network. Such explosive gases which can be usually detected in the oil factory and LPG pipeline are very dangerous for a human being. We analyzed the characteristics of a multi-dimensional sensor signals obtained from the nine sensors using the principal component analysis(PCA) technique. Also, we implemented a gas pattern recognizer using a multi-layer neural network with error back propagation learning algorithm, which can classify and identify the sorts of gases and concentrations for each gas. The simulation and experimental results show that the proposed gas recognition system is effective to identify the explosive gases. And also, we used DSP board(TMS320C31) to implement the proposed gas recognition system using the neural network for real time processing.

• Korean Journal of Optics and Photonics
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• v.22 no.4
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• pp.198-203
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• 2011

We have conducted a theoretical study to improve the detection limit of a surface plasmon resonance (SPR) sensor by co-localizing plasmonic fields and target molecules of interest. The fields were localized by nanograting antennas, while target molecules that participate in a molecular interaction were assumed to be co-localized by angled evaporation of a dielectric mask layer on the nanograting antennas. We have performed the evaluation using an overlap integral between distributions of plasmon fields and molecules and confirmed the correlation of the overlap with the sensitivity of an SPR sensor. Based on the calculated sensor characteristics, it was found that the sensitivity, if the fields and molecules are co-localized, can be as much as ten times that of non-colocalized structure.