• The Korean Journal of Food And Nutrition
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• v.14 no.6
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• pp.596-604
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• 2001

Twelve varieties of Korean rice and ten varieties of Japanese rice were selected. After being milled. they were analyzed about various physicochemical properties such as moisture, protein and amylose, a -amylase activity, gelatinization properties. And after being cooked with proper amount of water texture and other physical properties were measured by Texturometer, Tensipresser and Rheolograph-micro. Finally the sensory evaluation test was carried out. The results were as follows. 1. In case of protein contents, amylose contents and $\alpha$-amylase activity, Korean rice had a slightly higher value than Japanese As a consequence. Korean rice showed a little stronger hardness and a little weaker stickiness compared with Japanese rice. 2. Amylose contents showed very high correlation with other physicochemical properties and peak viscosity and gelatinization temperature of RVA, the ratio of stickiness to hardness( -Hl/Hl ) of Texturometer and the tan $\delta$(the ratio of dynamic loss to dynamic viscoelasticity) of Rheolograph-micro showed high correlation with other analyzed properties. 3. The ( -/+)work balance of low compression test(25% ) of Tensipresser analysis(texture analysis on the surface of cooked rice) and tan f of Rheolograph-micro showed very high correlation with sensory evaluation results. By using this parameters as major independent variables, some trials to derive high confidence multiple regression equations were accomplished. By the equations it would be possible to make an approximate pre-estimate of eating quality for unknown japonica rice.

• KIEE International Transactions on Electrophysics and Applications
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• v.3C no.2
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• pp.59-65
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• 2003

Electrical properties such as permittivity and tan$\delta$ of unaged (control) and aged (72 h at 18$0^{\circ}C$) mica/epoxy composites of 130 ${\mu}{\textrm}{m}$ thickness were measured and their surface conditions were characterized using scanning electron microscopy (SEM), Fourier transform infrared (FTIR), electron spectroscopy for chemical analysis (ESCA), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Both permittivity and tan6 of control specimens were higher than those of short-time aged specimens. FTIR results show a new peak at 1710 $cm^{-1}$ / for short-time aged specimens, originating from carbonyl group formed by the oxidation reaction during the aging process. ESCA results show that the binding energy at 532.9 eV representing the singlet state of oxygen ( $O_{1s}$) decreases by 13.7%, whereas that at 534.6 eV increases by 13.7%. Glass transition temperatures of control and short-time aged specimens are observed to be 95.4$^{\circ}C$ and 113.4$^{\circ}C$, which increase with the increase of aging time. TGA results indicate that the control specimens contain a smaller amount of volatile components than the short-time aged specimens.s.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.32A no.3
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• pp.471-481
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• 1995

Measurement factors for the dielectric properties of low dielectric loss materials (tan${\dalta}{\le}10^{-4}$) were investigated using the dielectric rod resonator method. It was shown that the relative conductivity (${\sigma}_{r}$) should be controlled within a 5% to obtain the standard deviations of less than 0.07 for permittivity .epsilon.r and 0.06${\times}10^{-4}$ for tan.delta.respectively. Surface resistivity (R$_s$) could be reduced when the surface roughness of parallelled conducting plate was less than 0.07 .mu.m. Measurement error for the permittivity was $\pm$0.02% independent of probe loop size, whereas the error in Q value was reduced with the decrease in probe loop size and also with the increase in the absolute values of Q. Reliable Q values were determined with the probe loop size of less than 4mm. The accurate for the distance between the measuring probe loop and the sample could be obtained when the insertion loss of resonant frequency ranged -15dB - -30dB.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.38 no.7
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• pp.511-523
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• 1989

This paper investigates physical properties, the electrical and mechanical characteristics of the epoxy resin with different curing methods and postcuring conditions at room temperature or cryogenic temperature (LN2). According to the results in this paper, first, it is found that the physical properties, electrical and mechanical characteristics of the epoxy resin are largely affected by the interior reaction temperature on the curing. Thus, in the fabrication of the sample, several excellent characteristics of the sample are obtained by controlling the interior reaction temperature of the epoxy resin. Second, the sample having optimal electrical and mechanical characteristics is obtained for the repetitive post-curing method at 100c in view point of the post-curing conditions of the epoxy resin. Third, it appears that tan and characteristics at LN2 temperature are about half of those at room temperature. Fourth, it appears that the dielectric strength of the epoxy resin at LN2 temperature is higher by about 0.6-1.0 MV/cm than that at room temperature. The heat-aging of the epoxy resin due to the micro-defect and excess fever-movement have been noticed to affect dielectric strength at LN2 temperature more significantly than at room temperature.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.10a
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• pp.31-35
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• 2000

We worried about the technology difference between our company and the advanced company at present motor market and are asked to set up the independent coil insulation system to accumulate insulation technology data. And to export our products at oversee market, we are asked to the evaluation of insulation performance to show our product excellence. In this study, we evaluated the insulation system of our motor, and studied the insulation diagnosis technology systematically to do site diagnosis. We are now accumulating the measured data. And also to reduce the initial insulation failure, we performed the insulation characteristic test and acquired the data to evaluate the initial soundness. We are doing the improvement of the insulation system. And also these data were used to new product development as very useful data, also will be used in the insulation deterioration diagnosis to estimate the remained life time which is very important data for the maintenance management. As the result, we were able to get our product reliability.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11b
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• pp.34-37
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• 2001

In this study, the capacitance-voltage properties of $(Sr_{1-x}\cdot Ca_x)TiO_3(0.05{\leq}x{\leq}0.20)$-based grain boundary layer ceramics were investigated. The ceramics were fabricated by the conventional mixed oxide method. The sintering temperature and time were $1480\sim1500^{\circ}C$ and 4 hours. respectively. The 2nd phase formed by the thermal diffusion of CuO from the surface leads to very excellent dielectric properties, that is, ${\varepsilon}_r$ >50000, tan$\delta$ <0.05, ${\Delta}C$ < ${\pm}10%.$ The capacitance is almost unchanged below about 20[V] but it decreases slowly about 20[V]. The results of the capacitance-voltage properties indicated that the grain boundary was composed of the continuous insulating layers.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.50 no.11
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• pp.539-543
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• 2001

ln this paper, the $Sr_{l-x}Ca_xTiO_3(0\leqx\leq0.2)-based$ grain boundary layer ceramics were fabricated to measure dielectric properties with the sintering temperature and the thermal treatment time. The sintering temperature and time were $1420~15206{\circ}C$, 4hours, and the thermal treatment temperature and time of the specimen were $l150^{\circ}C$, 1, 2, 3hours, respectively. The structural and the dielectric properties were investigated by SEM, X-ray, HP4194A and K6517. The average grain size was increased with increasing the sintering temperature, but it decreased up to 15mo1% with increasing content of Ca. X-ray diffraction analysis results showed that all specimens were the cubic structure, and the main peaks were moved to right and the lattice constant were decreased with increasing content of Ca. The appropriate thermal treatment time and temperature of CuO to obtain dielectric properties of $\varepsilon_r>50000,\; tan \delta<0.05\; and \;\DeltaC<\pm10%$ were 2hrs and $l150^{\circ}C$, respectively.

• Natural Product Sciences
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• v.18 no.2
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• pp.97-101
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• 2012

Six lignan compounds, 1-(17,21-dihydroxyphenyl)-9-(12,13-dihydroxyphenyl)-1-nonanone (malabaricone C) (1), 7'-(3',4'-methylenedioxyphenyl)-8,8'-dimethyl-7-(3,4-dihydroxyphenyl)-butane (2), 7'-(3',4'-dimethoxyphenyl)-8,8'-dimethyl-7-(3-methoxy-4-hydroxyphenyl)-butane (3), 7-(4-hydroxy-3-methoxyphenyl)-7'-(3',4'-methylenedioxyphenyl)-8,8'-lignan-7-methyl ether (4), (+)-erythro-(7S,8R)-${\Delta}^{8^'}$-7-hydroxy-3,4,3',5'-tetramethoxy-8-O-4'-neolignan (5), and (+)-erythro-(7S,8R)-${\Delta}^{8^'}$-7-acetoxy-3,4,3',5'-tetramethoxy-8-O-4'-neolignan (6), were isolated from the seeds of Myristica fragrans. The chemical structures of these compounds were determined on the basis of spectroscopic analyses including 2D NMR. Compounds 1 - 6 were evaluated for their cytotoxic activity against the HL-60, MCF-7, and A549 cancer cell lines in in vitro.

• Proceedings of the KIEE Conference
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• 1994.07b
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• pp.1526-1529
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• 1994

In hydro-generator, a groundwall insulation of stator windings gradually deteriorates due to mechanical, thermal, electrical and environmental stresses. These stresses combine to result in loose windings, delamination of the stator insulation and/or electrical tracking of the end winding, all of which can lead to stator insulation failures. Conventionally, off-line tests such as partial discharge measurement, DC/AC current test and ${\Delta}tan{\delta}$ test has been used for estimation of winding condition. However, off-line test requires large power supply and generator outage. In addition, major cause of insulation problems such as loose wedges and slot discharges may not be found with off-line diagnoses. This paper describes the on-line partial discharge measurement techniques in the generator stator windings. The experimental results from the UIAM #1 hydro-generator confirms a optimistic application of on-line generator diagnosis method as a reliable tool for evaluation of winding condition.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.25 no.11
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• pp.73-82
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• 2011

The solid insulation system of stator windings in high voltage rotational machines is usually aging in accordance with long time operation. The partial discharge test have been known to check whether insulation deterioration exist or not, and the PD test can effectively diagnose a solid insulation condition regardless of during operation(on-line) or not(off-line). The on-line PD measurement have proven to be a successful technique in monitoring stator insulation condition nowadays. This paper describes the characteristics of comparing the on-line PD measurement data using PDMS-HG(Partial Discharge Monitoring System for Hydro-electric Generator) installed in field with the off-line diagnosis measurement data(insulation resistance, winding resistance, PI, ${\Delta}tan{\delta}$ and PD) on hydro generator(13[kV]) stator windings. These results make good use of managing rotational machines through evaluating the solid insulation condition of stator windings.