• Transactions of the Korean Society of Mechanical Engineers B
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• v.27 no.12
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• pp.1699-1707
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• 2003

Coriolis mass flowmeter(CMF), which can measure the mass flow directly, is getting rapid attention for the industrial and custody transfer purpose. In order to study the characteristics and the applicability of CMF, it is tested with the national flow standard system. Two types of sensing tube, U-type and straight type, are employed in the test. Water, spindle oil and viscosity Standard Reference Material whose viscosities are 1, 20 and, 67 $\textrm{mm}^2$/s, respectively, are studied. It is shown that the linearity of CMF is getting deteriorated as the fluid viscosity increases, which is due to the zero drift and the relaxation time of the fluid. To test its applicability in the case of high pressured gas, it is calibrated using compressed air, It shows 1∼l.6 % deviations compared to the calibration results using water. It concludes that the fluid velocity in CMF should be lower than the sonic velocity. In addition, the effects of the vibration from the pipeline and pump on CMF as well as the long term stability are studied.

• Smart Structures and Systems
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• v.30 no.1
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• pp.63-74
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• 2022

The deformation coordination between a rock/soil mass and an optical sensing cable is an important issue for accurate deformation monitoring. A stress-controlled triaxial apparatus was retrofitted by introducing an optical fiber into the soil specimen. High spatial resolution optical frequency domain reflectometry (OFDR) was used for monitoring the strain distribution along the axial direction of the specimen. The results were compared with those measured by a displacement meter. The strain measured by the optical sensing cable has a good linear relationship with the strain calculated by the displacement meter for different confining pressures, which indicates that distributed optical fiber sensing technology is feasible for soil deformation monitoring. The performance of deformation coordination between the sensing cable and the soil during unloading is higher than that during loading based on the strain transfer coefficients. Three hypothetical strain distributions of the triaxial specimen are proposed, based on which theoretical models of the strain transfer coefficients are established. It appears that the parabolic distribution of specimen strain should be more reasonable by comparison. Nevertheless, the strain transfer coefficients obtained by the theoretical models are higher than the measured coefficients. On this basis, a strain transfer model considering slippage at the interface of the sensing cable and the soil is discussed.

• 한국생물공학회:학술대회논문집
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• 2001.11a
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• pp.545-548
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• 2001

Microbiologically influenced corrosion (MIC) of metal is common in the natural environment and sulfate reducing bacteria are representative microorganisms for MIC. We found that biofilm fomlation by SRB on the metal surface might be controlled by quorum sensing, which is a cell density dependent regulation of cell metabolism. As cell free culture fluids (spent media) of Desulfovibrio vulgaris and D. desulfuricans were tested for quontrn sensing related test strains, it was found that spent media of two SRB induced increased luminescence of Vibrio harveyi BB886 (sensor 1+, sensor 2-) and BB170 (sensor 1-, sensor 2+). Quorum activities of D. vulgaris and D. desulfuricans appeared to be parallel to growth patterns, i.e., it was low in the lag phase, highly increased in the exponential phase, and reached maximum in the stationary phase. Interestingly, however, luminescence of V. harveyi BB886 and BB170 induced by a unit cell mass of the SHB showed a maximal peak in the late lag phase. Hence, it was suspected that quorum sensing of these two SHB play unknown roles in shifting cells from dormant to growth stages.

• Proceedings of the Safety Management and Science Conference
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• 2009.11a
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• pp.461-470
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• 2009

A railroad has a benefit of the mass transportation of a passenger and cargo, but just a time of accident could cause a huge loss of a human life and property. Especially, a typhoon and a localized torrential downpour usually happened in summer season have caused average 38.29 times of the missing roadbed which support the railroad in recent 7 years. If a train would pass on this railroad which the roadbed was missed, there could be a huge accident and many people will die. But, the security issue is not satisfied because the method of sensing the missing roadbed is depending solely on the naked eye inspection by a person in charge. So, in this study, I would like to suggest the missing roadbed real-time sensing and train operation system to reduce the possibility of the railroad accident by controlling the operation of train when the missing roadbed condition would be sensed in the real-time system.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.1767-1772
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• 2008

A microcantilever is a well-known MEMS structure for sensing bio-chemical molecules. When bio-chemical molecules are adsorbed on the microcantilever's surface, resonance frequency shift is generated. There are two issues in this phenomena. The first one is which one between mass change and surface stress change effects is more dominant on the resonance frequency shift. The second one is what will be the performance change when the boundary condition is changed from cantilevers to double clamped beams. We have studied the effect of surface stress change and compared it with that of mass change by using FEM analysis. Furthermore, for microstructures having different boundary conditions, we have studied Q-factor, which determines the detection limit of micro/nano mechanical sensors.

• Journal of the Korean Society of Mechanical Technology
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• v.13 no.4
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• pp.93-99
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• 2011

This paper presents a new type of optical silicon accelerometer using deep reactive ion etching (DRIE) and micro-stereolithography technology. Optical silicon accelerometer is based on a mass suspended by four vertical beams. A vertical shutter at the end of the mass can only moves along the sensing axis in the optical path between two single-mode optical fibers. The shutter modulates intensity of light from a laser diode reaching a photo detector. With the DRIE technique for (100) silicon, it is possible to etch a vertical shutter and beam. This ensures low sensitivity to accelerations that are not along the sensing axis. The microstructure for sensor packaging and optical fiber fixing was fabricated using micro stereolithography technology. Designed sensors are two types and each resonant frequency is about 15 kHz and 5 kHz.

• Proceedings of the Korean Ceranic Society Conference
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• 2002.10a
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• pp.87.1-87
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• 2002

• Journal of the Korea Institute of Information and Communication Engineering
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• v.9 no.3
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• pp.595-600
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• 2005

A micro flow sensor on silicon substrate allows the fabrication of small components where many different functions can be integrated so that the functionality of the sensors can be increased. Further more, the small size of the elements these sensors can be quite fast. A thermal mass flow sensor measures the asymmetry of temperature profile around the heater which is modulated by the fluid flow. In normal, a mass flow sensor is composed of a central heater and a pair of temperature sensing elements around the heater A new 2-D wide range micro flow sensor structure with three pairs of temperature sensors and a central heater was proposed and numerically simulated by Finite Difference formulation to confirm the feasibility of the flow sensor structure in time domain.

• The Journal of the Acoustical Society of Korea
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• v.26 no.1
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• pp.42-47
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• 2007

In this paper. we have studied improvement in sensitivity by increasing the frequency of SAW sensors for detecting the immobilization and hybridization of DNA. The sensor consists of twin SAW delay lines operating at 200MHz, a sensing channel and a reference channel. fabricated on $36^{\circ}$ rotated Y-cut X-propagation $LiTaO_3$ crystals. The optimum concentration of probe and target DNA was decided for the improvement of detection mechanism. and digital syringe pump system was used to reduce the human errors. The hybridization between immobilized probe DNA and target DNA on the gold-coated delay line results in mass loading on the delay line of the sensing channel. Thus, the relative frequency change was monitored in relation to the mass loading. The measurement results showed a good response of the sensor to the DNA hybridization with a maximum sensitivity level up to 0.066ng/m1/Hz.

• Journal of Microbiology and Biotechnology
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• v.17 no.10
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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.