• 한국산업융합학회 논문집
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• 제4권4호
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• pp.371-378
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• 2001

This paper proposes a method to detect the misfired cylinder using a new misfire detection index. The new method of misfired cylinder is a comparison of pressure gradient during the blowdown period of exhaust stroke. If a misfire occurs, the engine will he lost some power and consumes the more fuel and the torque will be unsteady. Most of all, the misfire affects a bad influence of the 3-way catalyst and emits unburned hydrocarbon in the air. To prevent these unusual phenomena and eliminate the factor of the environmental pollution, it is important to detect the misfired cylinder. To do the experiment, set up the assist device on the manifold. This assist device is not deformed for conventional exhaust manifold and installed in the end of the exhaust manifold. Experimental results showed that the method using the mean gradient pressure index is proven to be effective in the detection of misfired cylinder on gasoline engine regardless loads and revolutions of the engine.

• Wind and Structures
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• 제3권3호
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• pp.159-175
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• 2000

Many practical time series, including pressure signals measured on roof-corners of low-rise buildings in quartering winds, consist of relatively quiescent periods interrupted by intermittent transients. The dyadic wavelet transform is used to detect these transients in pressure time series and a relatively simple pattern classification scheme is used to detect underlying structure in these transients. Statistical analysis of the resulting pattern classes yields a library of signal "building blocks", which are useful for detailed characterization of transients inherent to the signals being analyzed.

• 한국재료학회지
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• 제28권1호
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• pp.1-5
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• 2018

Gas detection is necessary for various reasons, including the prevention of gas leakages and the creation of necessary environmental conditions. Among the gas detection methods, leakage of gas can be confirmed using materials that undergo color changes that are easily distinguished by the naked eye. Metal nanoparticles (NPs) experience variations in their absorption wavelengths under the localized surface plasmon effect (LSPR) with mechanical stresses, which change the distance between NPs. In this study, we attempted to detect the presence of gas utilizing the LSPR-related color change of a chain of Au NPs. The assembly of Au NPs, arranged in a chain shape, experienced a color change from dark blue to purple with a change in the distance between the NPs by applying a physical force, i.e., compression, stretching, and gas pressure. As the force of compression and the degree of stretching increased, the absorption wavelength shifted from doublet peaks at 650 and 550 nm to a singlet peak at 550 nm. Further, applying gas pressure caused an identical color change. With this result, we propose a method that could be applied to all gases that require detection based on gas pressure.

• 상하수도학회지
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• 제35권1호
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• pp.15-25
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• 2021

In this study, a method of leakage detection was proposed to locate leak position for a reservoir pipeline valve system using wavelet coherence analysis for an injected pressure wave. An unsteady flow analyzer handled nonlinear valve maneuver and corresponding experimental result were compared. Time series of pressure head were analyzed through wavelet coherence analysis both for no leak and leak conditions. The leak information can be obtained through either time domain reflectometry or the difference in wavelet coherence level, which provide predictions in terms of leak location. The reconstructed pressure signal facilitates the identification of leak presence comparing with existing wavelet coherence analysis.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제43회 하계 정기 학술대회 초록집
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• pp.257-257
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• 2012

Fault detection was carried out in a etcher of capacitive coupled plasma with OES (Optical Emission Spectroscopy) and impedance by VI probe that are widely used for process control and monitoring at semiconductor industry. The experiment was operated at conventional Ar and Fluorocarbon plasma with variable change such as pressure and addition of N2 and O2 to assume atmospheric leak, RF power and pressure that are highly possible to impact wafer yield during wafer process, in order to observe OES and VI Probe signals. The sensitivity change on OES and Impedance by VI probe was analyzed by statistical method including PCA to determine healthy of process. The main goal of this study is to find feasibility and limitation of OES and Impedances for fault detection by shift of plasma characteristics and to enhance capability of fault detection using PCA.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 1998년도 하계종합학술대회논문집
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• pp.573-576
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• 1998

In this paper, we devised pulse detection transducer that has non-differential characteristics for pulse detection on chongu arterial. The transducer consist of load cell and driving electronic circuits. Load cell consist of cantilever and two metal film strain gauge. The pressure signal from chongu artery is delivered to load cell using artery rider that attached to cantilever. Therefore the pressure pulse signal can obtain by the developed transducer. As the results of experiment, the developed transducer has a good linearity at pressure to voltage conversion and acan detect non-differential pulse signal from chongu artery.

• Journal of Microbiology and Biotechnology
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• 제8권2호
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• pp.124-128
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• 1998

The procedures currently used for determining microbiological quality of natural mineral water recommend filtration through membrane filters. In this study, we evaluated the effect of vacuum pressure for the accurate detection of bacteria from water samples seeded with Escherichia coli. We observed that the number of E. coli detected increased with increasing vacuum pressure. In order to examine the retention rate of bacteria in the holes of the membranes under the different pressures, the membrane filters were removed after filtration, washed with sterile water by vortexing, and placed on m-Endo agar plates. With all the filters tested, the number of E. coli retained within the filters at negative 600 mmHg was approximately 10 to $20\%$ higher than that obtained with 100 mmHg. These results demonstrate that the vacuum pressure exerted during the filtration procedure may affect the fixation of bacteria into some portions of openings in the membrane filter.

• Journal of Advanced Marine Engineering and Technology
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• 제30권3호
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• pp.449-454
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• 2006

We present a pressure sensor based on the mechanically induced long-period fiber gratings (LPFG) for detecting the multi-location strain variation. The theoretical analysis is performed using a graphic method for a weakly guiding step-index fiber. The calculated results are in good agreement with the experimental results. In this study, from the fact that the optical parameters of a single-mode fiber slightly differ from manufacturing company to manufacturing company, the multipoint pressure-detection sensor systems composed two identical LPFGs are realized. When the pressure is applied two LPFG sensors at once, the resonance peaks are separated as much as about 40 nm. These types of sensor systems are well suited as a multipoint monitoring of strain or temperature in the ship or the smart structure.

• 대한의용생체공학회:학술대회논문집
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• 대한의용생체공학회 1997년도 추계학술대회
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• pp.428-431
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• 1997

This study is the basic research on esophageal balloon dialation with automatic detection of the pressure change in the balloon and analysis using personal computer. In conventional method, the esophageal stricture is cured by surgically. Recently, balloon dialation method has been proposed and is popularized. In balloon dialation, detecting esophageal rupture is very important. When using radiological investigation, the leak of contrast medium is very dangerous. In proposed method, the detection of esopageal rupture can be peformed by detecting and analyze the pressure change of dialation balloon. Experimental system is composed of balloon catheter, pressure pump, pressure sensor, A/D converter and PC.

• 센서학회지
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• 제33권3호
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• pp.165-172
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• 2024

In this study, we investigated the detection properties of piezoresistive carbon nanotubes/polydimethylsiloxane (CNT/PDMS) devices with porous structures under applied pressure. The device, having dimensions of 10 mm × 10 mm × 5 mm, was fabricated with a porosity of 74.5%. To fabricate piezoresistive CNT/PDMS devices, CNTs were added using two different methods. In the first method, the CNTs were mixed with PDMS before the fabrication of the porous structure, while in the second, the CNTs were coated after the fabrication of the porous structure. Various detection properties of the fabricated devices were examined at different applied pressures. The CNT-coated device exhibited stable outputs with lesser variation than the CNT-mixed device. Moreover, the CNT-coated device exhibited improved reaction properties. The response time of the CNT-coated device was 1 min, which was approximately about 20 times faster than that of the CNT-mixed device. Considering these properties, CNT-coated devices are more suitable for sensing devices. To verify the CNT-coated device as a real sensor, it was applied to the gripping sensor system. A multichannel sensor system was used to measure the pressure distribution of the gripping sensor system. Under various gripping conditions, this system successfully measured the distributed pressures and exhibited stable dynamic responses.