• Journal of Microbiology and Biotechnology
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• 제17권10호
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• pp.1598-1606
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• 2007

A new series comprising 7 analogs of N-(sulfanyl ethanoyl)-L-HSL derivatives, 2 analogs of N-(fluoroalkanoyl)-$_L$-HSL derivatives, N-(fluorosulfonyl)-L-HSL, and 2,2-dimethyl butanoyl HSL were synthesized using a solid-phase organic synthesis method. Each of the 11 synthesized compounds was analyzed using NMR and mass spectroscopies, and molecular modeling studies of the 11 ligands were performed using SYBYL packages. Thereafter, a bacterial test was designed to identify their quorum-sensing inhibition activity and antifouling efficacy. Most of the synthesized compounds were found to be effective as quorum-sensing antagonists, where antagonist screening revealed that 10 among the 11 synthesized ligands were able to antagonize the quorum sensing of A. tumefaciens.

• KSBB Journal
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• 제22권6호
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• pp.378-386
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• 2007

바이오센싱 디바이스는 본질적으로 생체인식소재와 신호전달장치로 구성된 집적화, 소형화된 분석시스템으로 많은 장점을 가지고 있다. 고민감도, 선택도, 단순성, 다성분 측정능력, 즉시측정능력 뿐 아니라 매우 작고, 고가의 장치가 필요없는 장점이 있다. 바이오센싱 디바이스의 개발을 위해서는 두 가지의 핵심요소기술이 필요하다. 이것은 생체인식소재모듈의 제작 (리셉터 개발 및 고정화기법)과 신호발생기술을 포함한 신호전달장치의 개발이다. 효소, DNA/RNA, 단백질, 세포 등의 다양한 생체인식소재가 바이오센싱 디바이스 제작을 위해 이용되어져 왔고, 신호전달시스템도 전기화학적, 광학적, mass sensitive transducer를 중심으로 매우 활발히 연구되어져 왔다. 본 고에서는 최근 개발된 바이오센싱디바이스에 대해 다루고, 향후 전망에 대해 논하고자 한다.

• 대한원격탐사학회지
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• 제36권6_3호
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• pp.1681-1690
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• 2020

532와 1064 nm 두 파장 관측 채널을 구비하고 수평으로 360° 스캐닝 관측이 가능한 스캐닝 라이다 시스템을 개발하였다. 또한, 두 파장에서의 후방산란계수를 이용하여 미세먼지를 PM2.5-10(조대)와 PM2.5(미세)입자로 구분하는 분석도 개발하여 스캐닝 라이다 시스템의 데이터 분석에 적용하였다. 개발된 스캐닝 라이다를 이용한 울산 온산공단에서 관측에서 각각 22 - 110 ㎍/㎥과 7 - 78 ㎍/㎥의 분포를 보이는 PM10과 PM2.5의 질량 농도를 성공적으로 산출하였다. 분석된 결과는 라이다 관측 영역 주변에서 지상에서 측정된 질량농도와 유사한 값을 보였으며, 공장 등에서 배출되는 지점에서는 이 각각 80-110 ㎍/㎥과 60-78 ㎍/㎥의 고농도가 측정되는 사례를 확인하였다.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2002년도 Proceedings of International Symposium on Remote Sensing
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• pp.587-592
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• 2002

A new digital correlator fur an airborne synthetic aperture radiometer was designed in order to replace the conventional analog correlator unit which will become very complicated while the number of channels is increasing. The digital correlator uses digital IQ demodulator instead of the intermediate frequency (IF) phase shifter to make the correlation processing performed digitally at base band instead of analogly at IF. This technique has been applied to the digital receiver in softradio. The down-converted IF signals from each pair of receiver channels become low rate base-band digital signals after under-sampled, Digitally Down-Converted (DDC), decimated and filtered by FIR filters. The digital signals are further processed by two digital multipliers (complex correlation), the products are integrated by the integrators and finally the outputs from the integrators compose of the real part and the imaginary part of a sample of the visibility function. This design is tested by comparing the results from digital correlators and that from analog correlators. They are agreed with each other very well. Due to the fact that the digital correlators are realized with the help of Analog-Digital Converter (ADC) chips and the FPGA technology, the realized volume, mass, power consumption and complexity turned out to be greatly reduced compared with that of the analog correlators. Simulations show that the resolution of ADC has an influence on the synthesized antenna patterns, but this can be neglected if more than 2bit is used.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회B
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• pp.2753-2756
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• 2007

In the present study, we reduce the drag and lift fluctuations of the sphere by providing a linear proportional control. For this purpose, we measure the radial velocity along the centerline in the wake and provide blowing and suction at a part of sphere surface based on the measured velocity. Zero-net mass flow rate is satisfied during the control. This control is applied to the flow over a sphere at Re=300 and 425. We vary the sensing location at $0.8d{\leq}X_s{\leq}1.3d$ and find that the most effective sensing region coincides with the location at which minimum correlation between the lift and sensing-velocity directions occurs. As a result, the lift and drag fluctuations are significantly reduced.

• 대한기계학회논문집A
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• 제21권7호
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• pp.1013-1020
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• 1997

Among various gyroscopes, the vibrating gyroscope has advantages such as compact size, mass-productivity and low cost. However this kind of gyroscope usually suffer from low linearity and low signal to noise ratio. Therefore, it is necessary to study on vibrating gyroscope to improve performance. In this paper, triangular cross section si selected in consideration for several points. The existing designs of exciting and sensing have some problems such that small signal size and low linearity. This paper proposes new design of exciting and sensing which is named one period exciting and the other period sensing. This design improves signal size, but it cannot improve linearity. This is because above two designs are the same open-loop type. So, another new design is proposed, which is named rebalancing, is applied to one period exciting and the other period sensing. This design are closed-loop type. It feedbacks the output signal. According to control theory, it can improve linearity. The circuits of each design are realized and used to calibration test. Calibration results show that new design of rebalancing improves linearity and signal size.

• 전자공학회논문지D
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• 제35D권4호
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• pp.93-100
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• 1998

Pyoelectric infrared detectors based on La-modified PbTiO3 (PLT) thin films have been fabricated by RF magnetron sputtering and micromachining technology. The detectors form Pb$_{1-x}$ La$_{x}$Ti$_{1-x}$ O$_{3}$ (x=0.05) thin film ferroelectric capacitors epitaxially grown by RF magnetron sputtering on Pt/MgO (100) substrate. The sputtered PLT thin film exhibits highly c-axis oriented crystal struture that no poling trealization for sensing applications is required. This is an essential factor to increase the yield for realization of an infrared image sensor. Micromachining technology is used to lower the thermal mass of the detector by giving maximum sensor efficiency. Polyimide is coated on top of the sensing elements to support the fragile structure and the backside of the MgO substrate is selectively eteched to reduce the heat loss. The sensing element exhibited a very high detectivity D* of 8.5*10$^{8}$ cm..root.Hz/W at room temperature and it is about 100 times higher than the case of micromachining technology is not used. a sensing system that detects the position as well as the existence of a human body is realized using the array sensor.sor.

• 대한원격탐사학회지
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• 제21권1호
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• pp.51-57
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• 2005

The currently operating NASA/GFZ Gravity Recovery and Climate Experiment (GRACE) mission is designed to measure small mass changes over a large spatial scale, including the mapping of continental water storage changes and other geophysical signals in the form of monthly temporal gravity field. The European Space Agency's Gravity field and steady state Ocean Circulation Explorer (GOCE) space gravity gradiometer (SGG) mission is anticipated to determine the mean Earth gravity field with an unprecedented geoid accuracy of several cm (rms) with wavelength of 130km or longer. In this paper, we present a summary of present GRACE studies for the recovery of hydrological signals in the Amazon basin using alternative processing and filtering techniques, and local inversion to enhance the temporal and spatial resolutions by two-folds or better. Simulation studies for the potential GRACE detection of slow deformations due to Nazca-South America plate convergence and glacial isostatic adjustment (GIA) signals show that these signals are at present difficult to detect without long-term data averaging and further improvement of GRACE measurement accuracy.

• 한국구조물진단유지관리공학회 논문집
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• 제15권1호
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• pp.209-214
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• 2011

본 연구에서는 효과적인 풍력발전기 블레이드의 상태 모니터링을 위하여 대표적 손상형태 중 하나인 로터의 질량 불균형으로 인한 이상상태를 감지할 수 있는 기법을 제안하였다. 이를 위하여 수평축 3-블레이드 풍력발전기를 대상으로, 블레이드 1개의 질량을 증가시키면서 로터의 질량 불균형 조건을 구현한 후 전체 풍력발전기에 대한 동력학 시뮬레이션을 수행하였다. 질량 불균형이 발생하면 부가질량에 의한 원심력에 의하여 나셀의 로터 회전축에 대한 횡방향 진동이 발생하고, 부가 질량의 크기가 커질수록 나셀 횡방향 진동의 진폭이 거의 선형적으로 증가함을 알 수 있었다.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 1998년도 Proceedings of International Symposium on Remote Sensing
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• pp.399-403
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• 1998

Absorption coefficient per mass unit of particles, specific absorption coefficient, is one of main parameters in developing algorithms for ocean color remote sensing. Specific absorption coefficient of chlorophyll (a$^*_{ph}$) and suspended sediment (SS) were analyzed by "wet filter technique" and "Kishino method" for data sets observed in the Yellow and Mediterranean Seas. A new data-recovering method for the filter technique was also developed using spectrum slopes. This method recovered the baseline of spectrum that was often missed in the Kishino method. High a$^*_{ph}$($\lambda$) values in the oligotrophic Mediterranean Sea and low values in the Yellow Sea were observed, spanning over the range of 0.02 to 0.12 $m^2$/mg, at the chlorophyll maximum absorption wavelength 440nm. The empirical relationship between a$^*_{ph}$ and chlorophyll concentration was found to fit a power function, which was slightly different from that proposed by Bricaud et ai. (1995). Absorption specific coefficients for suspended sediment (a$^*_{SS}$) didn't show any relationship with concentrations of suspended sediment. However, the average value of a$^*_{SS}$ at 440nm was close to the specific absorption coefficient of soil (loess) measured by Ahn (1990). The more-pronounced variability of a$^*_{SS}$ than a$^*_{ph}$ perhaps can explain more wide range of size-distribution for SS, which were determined by their specific gravity and agitation of water mass in the sea surface.