• Archives of Pharmacal Research
• /
• v.29 no.5
• /
• pp.343-347
• /
• 2006

A new flavanone Persinol (1) and the new flavanone glucosides persinosides A (2) and B (3), along with known flavonoids (4 and 5) have been isolated from the ethyl acetate soluble fraction of the whole plants of Aerva persica. Their structures were elucidated on the basis of extensive analysis of nuclear magnetic resonance (1D & 2D-NMR) spectral data. All of them showed profound antioxidative activities by DPPH and cytochrome-c-reduction assays using the HL-60 cell culture system.

• The Journal of the Acoustical Society of Korea
• /
• v.26 no.1E
• /
• pp.27-32
• /
• 2007

Hydraulic actuator and electro-magnetic liner actuator have been used as typical active vibration control methods. However these methods have many kinds of disadvantages such as causing space limit, difficult maintenance, complicate structures, etc. The purpose of this paper was to study on the possibility of active vibration control using piezoelectric transducer. Piezoelectric transducer generated a vibration and GIC (General Impedance Converter) amplifier was adopted to give adjustable vibration signal to transducer and high amplitude of vibration. Resonance frequency of piezoelectric transducer was controlled by GIC amplifier and higher amplitude of vibration was achieved. Finally active vibration control using piezoelectric transducer was performed.

• Smart Structures and Systems
• /
• v.17 no.1
• /
• pp.123-134
• /
• 2016

The evolution of the electro-mechanical impedance (EMI) of a piezoelectricity (PZT) sensor was investigated to determine the setting times of cement paste in this study. The PZT sensor coated with non-conductive acrylic resin was embedded in fresh cement paste and the EMI signatures were continuously monitored. Vicat needle test and semi-adiabatic calorimetry test were also conducted to validate the EMI sensing technique. Significant changes in the EMI resonance peak magnitude and frequency during the setting period were observed and the setting times determined by EMI sensing technique were relevant to those measured by Vicat needle test and semi-adiabatic calorimetry test.

• Elastomers and Composites
• /
• v.55 no.2
• /
• pp.103-107
• /
• 2020

Herein, resin-formed polysilsesquioxanes (PSSQs) were synthesized using monomolecular fluoro silane as a precursor. The synthesized PSSQs exhibited anti-smudge performance and were used as coating liquid. Two structures were acquired by controlling the amount of the silane precursor and the K₂CO₃ catalyst; these materials were used to prepare the anti-smudge coating liquid solution. The synthesized product was analyzed by various methods such as nuclear magnetic resonance spectroscopy, X-ray diffraction analysis, gel permeation chromatography, and water contact angle measurement. The results confirmed that the as-synthesized PSSQs exhibited the ladder structure and had a molecular weight of 5,117 g/mol and water contact angle of 102.31°.

• Magazine of the Korea Concrete Institute
• /
• v.3 no.3
• /
• pp.121-128
• /
• 1991

Thicknesses of the hase concrete blocks supportmg large machmes were estimated by analyzing the res- 0 ¬nance modes of mechanical Vibrations The vibration was produced by the mechanical impact with steel ball drop and detected by a wideband comcal piezoelectric transducei. The detected signals were analyzed by FFT and thicknesses of specimen were determined by the resonant frequency of vibratIon. For the layered concrete block, the estimated thickness is dependent on the acoustic reflective index at the boundary between layers. The estimated thickness up to 100em were in goo:l agreement with the real value. In additlOn. this technique could be applicable to the estimation of the bondmg status of the layered structures.

• KSBB Journal
• /
• v.15 no.5
• /
• pp.423-427
• /
• 2000

Intense research on biosensors has been performed in a number of different institution over the past 15 years, but relatively few commercial products have resultingly, the blood glucose sensor is a good example of a product which penetrated the market. However recently, the development of electrochemical and optical technologies has accelerated the turnover of the research as is illustrated by a rapid increase in the number of point-of-care diagnostic systems and analytical devices. Examples of such biosensors used in the fields of medical diagnostics, bioprocess control, and environmental monitoring are described, and summarized in an introduction to their characteristics, structures, and functions, given.

• Journal of Pharmaceutical Investigation
• /
• v.20 no.4
• /
• pp.217-222
• /
• 1990

New antitumor-active pt(II) complexes of trans-l-diamine cyclohexane containing diphosphines as a leaving group were synthesized. The structures of the pt(II) complexes were determined by analyzing the infrared and $^{31}P-nuclear$ magnetic resonance spectra. Antitumor activities of the pt(II) complexes were tested against murine leukemia $L_{l210}$ according to the protocol of the National Cancer Institute. All the pt(II) complexes Synthesized were antitumor-active. In particular, water-soluble $[pt(trans-l-dach) (DPPP)](NO_3)_2$ exhibited excellent antitumor activity, giving T/C % values of 341 and 356 respectively, each with four cured mice out of six at a dose of 25 mg/kg. These pt(II) complexes are considered to be worthy of further development.

• Natural Product Sciences
• /
• v.22 no.1
• /
• pp.41-45
• /
• 2016

Extraction and fractionation of Pulsatilla koreana flowers followed by, repeated open column chromatography for EtOAc and n-BuOH fractions yielded four flavonoid glycosides, namely, astragalin (1), tiliroside (2), buddlenoide A (3), and apigenin-7-O-(3"-E-p-coumaroyl)-glucopyranoside (4). The chemical structures of these flavonoid glycosides were elucidated on the basis of various spectroscopic methods including electronic ionization mass spectrometry (EI-MS), 1D NMR ($^1H$, $^{13}C$, DEPT), 2D NMR (gCOSY, gHSQC, gHMBC), and infrared (IR) spectrometry. This study represents the first report of the isolation of the flavonoid glycosides from the flowers of P. koreana.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 1996.10a
• /
• pp.248-254
• /
• 1996

In this paper active vibration control system using a linear oscillatory actuator (LOA) is studied to suppress structural vibration. Being compared with a hydraulic actuator, a LOA has simplified structure and requires a few elements, so it has lots of merits with respect to economics and maintenance. Performance test of active vibration control system using LOA is carried out on a steel test structure under base excitation. From this test it is confirmed that acceleration level of test structure is reduced near the resonance region. In the future research on the application to large to structures will be studied.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2004.11a
• /
• pp.97-102
• /
• 2004

The Characteristics of noise and vibration by heavy-weight floor impact sound was studied. Resonance frequency increased a little in structures that use damping material in living room and bedroom, and acceleration waves length that respond became short, and displayed aspect that oscillation level decreases. Result that measure sound pressure level, structure that compare and applies damping materials with structure that apply the resilient materials from 63Hz lower part that impact energy is concentrated in energy spectrum of heavy-weight floor impact sound displayed result that sound pressure, level decreases remarkably. Therefore, according to use of damping materials, confirmed reduction effect of heavy-weight floor impact sound.