• Mass Spectrometry Letters
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• v.8 no.1
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• pp.8-13
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• 2017

Analysis of quinidine for fish tissues using single drop microextraction (SDME) coupled with atmospheric pressure matrix assisted laser desorption/ionization mass spectrometry (AP-MALDI-MS) are reported. Optimization conditions; such as extraction solvent, extraction time, pH of the aqueous solution, salt additions (NaCl), stirring rate, matrix type and concentration are investigated. Linear dynamic range (${\mu}M$), limit of detection, relative recovery%, and enrichment factor are 0.08-9.2, 0.05, $94.8{\pm}3.1-98.5{\pm}3.3%$, $4.34{\pm}0.28-4.40{\pm}0.30$, respectively. SDME-AP-MALDI-MS shows good intraday and interday reproducibility.

• Korean Journal of Pharmacognosy
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• v.48 no.1
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• pp.93-96
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• 2017

Ephedra alkaloids, (-)-ephedrine, (+)-pseudoephedrine, (-)-N-methylephedrine, (+)-N-methylpseudoephedrine, (-)-norephedrine and (+)-norpseudoephedrine, from ephedra herb are sympathomimetic agonists causing an increase of metabolism, blood pressure and perspiration. In this study, we developed the validation method of (+)-pseudoephedrine and (-)-ephedrine, two major ephedra alkaloids in Ephedra spp., by high-performance liquid chromatography-ultraviolet spectrometer (HPLC-UV). HPLC analysis was performed using a HECTOR-M C18 column operating at $35^{\circ}C$, and UV detection at 215nm. The mobile phase used a gradient flow with 25 mM SDS in water (A) and acetonitrile (B).

• Journal of the Korean Society for Nondestructive Testing
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• v.30 no.6
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• pp.521-526
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• 2010

Gas transmission pipelines are often inspected and monitored using the magnetic flux leakage method. An inspection vehicle known as a "pig" is launched into the pipeline and conveyed along the pipe by the pressure of natural gas. The pig contains a magnetizer, an array of sensors and a microprocessor-based data acquisition system for logging data. This paper describes magnetic flux leakage (MFL) signal processing used for detecting mechanical damages during an in-line inspection. The overall approach employs noise removal and clustering technique. The proposed method is computationally efficient and can easily be implemented. Results are presented and verified by field tests from an application of the signal processing.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2014.04a
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• pp.662-663
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• 2014

In most vehicle manufactures have traditionally relied on find-fix method of human auditor, mainly due to variation excitation source. To solve the BSR noise, the requirements for BSR test are presented in terms of detection of noise source, analysis of time-frequency and sound pressure, sound quality for noise. A number of new technology direction, particularly in the field of noise source identification application and psycho-acoustics from the Zwicker's sound quality parameter, the computed objective sound metrics and subjective jury test result.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1998.04a
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• pp.582-589
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• 1998

This paper presents the analysis results of ex-core and in-core neutron noise, acceleration signals and pressure fluctuation measured at Ulchin Nuclear Unit 1 & 2 to identify and monitor the reactor internals vibration including fuel motion. A phase separation algorithm developed by authors was applied to the neutron noises to clearly identify the reactor internals vibratory motion. The beam mode frequency of the core support barrel was identified to be 8Hz and the shell mode to be 20Hz. The first frequency of the fuel assembly was also found to be 3Hz, while first two acoustic frequencies of the primary coolant system were 6 and 17.5Hz. By monitoring and analyzing these frequencies periodically, it is possible to diagnose the operating condition of reactor internals and to provide an early detection of faults for the predictive maintenance.

• The Journal of the Acoustical Society of Korea
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• v.8 no.1
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• pp.75-80
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• 1989

A Mach-Zehnder interferometer using single mode optical fiber was constructed which operates in homodyne detection scheme. Its response to air-borne soun pressure was examined experimentally. A signal stabilizer was developed for maintaining optical fiber interferometer in quadrature condition using a cylindrical piezoelectric stretcher. This maintains the optical fiber sensor at a maximum sensitivity in the presence of the phase drift caused by temperature fluctuation and other types of environmental disturbances.

• Proceedings of the KOSOMBE Conference
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• v.1992 no.05
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• pp.71-74
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• 1992

This paper describes research about the realization of computerized radial pulse diagnosis system in order to remove the subjectivity of a diagnostician, when diagnostician diagnoses a sickness using tactile percept ion in korean traditional medicine. Using radial pulse wave detection system, we effectively measured pressure radial pulse rave and after analyzing it, we detected the characteristic parameters and also quantified it and then we objectified more or less the judgement standard of radial pulse diagnosis by the aids of a clinical expert. on this base, we confirmed the possibility for realizing of automatic radial pulse diagnosis by radial pulse diagnosis system.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2018.05a
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• pp.563-564
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• 2018

Recently the accidents of residual children in vehicles have frequently occurred. In order to prevent this, it is necessary to supplement safety devices together with children safety education. In this paper, we proposed a system to prevent the accidents of leaving kindergarten children in the school bus by detecting the events such as movement, pressure, voice.

• Electrical & Electronic Materials
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• v.11 no.10
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• pp.78-80
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• 1998

Metallo-phthalocyanines(MPcs) are very sensitive to toxic molecules such as electron affinitive NO2 gas and also chemically and thermally stable since losts of MPcs have been studied for the potential chemcial gas sensors for $NO_2$ using their electrical conductivity. In this study, thin films of octa-dodecyloxy copper -phthalocyanine were prepared by Langmuir-Blodgett(LB) method and characterized by using UV/Vis absorption spectroscopy, and ellipsometry. It was found that the proper transfer surface pressure for the film deposition was 25mN/m and the limiting area per molecule was $112\AA$/molecule. The film thickness of one layer was $64\AA$. Current-voltage(I-V) characteristics of these films were investigated as a function of film thickness.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1989.06a
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• pp.114-117
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• 1989

An infrasonic wide band transducer fabricated by polytetrafluoroethylene(PTFE)is studied experimentally. The sensitivity of the transducer depends largely on the surface charge of the Electret and is typically between-50 and -62[dBV] for a sound-pressure level of 1[ubar]. The sensitivity of the transducer does not decay over periods of the order of years at room temperature. The frequency response is within 1.5[dB] from 1 to 6,000[Hz] and within 12[dB] from 0.05[Hz] to 1[Hz] respectively. The resonance frequency of the element is 510 [Hz]. We conjectures that the element is applicable to accustics, communication system, seismological observation and other similar filed.