• Food Science and Biotechnology
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• v.17 no.5
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• pp.931-939
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• 2008

The objective of this study was to investigate the enolization reaction and the antioxidant activity of caramelization products (CPs) obtained by caramelization browning of glucose and fructose solutions prepared at a pH ranging from 7.0 to 12.0 at varying temperatures ($80-180^{\circ}C$). The degradation of sugars rapidly increased at a high alkaline pH (10.0-12.0), and fructose degraded more rapidly than glucose (p<0.05). As the pH increased, the degree of sugar enolization was higher in fructose than in glucose. Browning and the formation of intermediate degradation products increased with the increase in heating temperatures. The browning development was dependent upon the type of sugar, and it was generally higher at alkaline pH than at neutral pH. The reducing power and 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity of the CPs increased with the increase in browning and formation of large amounts of intermediates. Therefore, the CPs with pronounced antioxidant activity can be prepared by heating fructose or glucose solutions that have a very alkaline pH to high temperatures.

• Animal cells and systems
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• v.13 no.3
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• pp.267-274
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• 2009

The dissociative culture technique of Aplysia neuron is one of the key methods that have been used for studies of cellular and molecular mechanisms of neuronal functioning. However, despite the advantages this method offers as an experimental model, its technical efficiency has had room for improvement. In this study, we examined certain putative factors that might affect the culture quality. The effects of neuronal damage induced by physical injuries, heat shock, and surface protein degradation were evaluated along with the correlation between the culture quality and animal behavior. As a result, we found that physical injury can be a critical factor that affects culture quality, whereas the heat shock and surface protein degradation had negligible effect on it. In addition, we discovered that siphon retraction time was not a good measurement for healthy neurons. Based on these findings, we suggest here an improved method in which the degree of physical injury is reduced by means of multiple protease treatment.

• Journal of Hydrogen and New Energy
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• v.1 no.1
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• pp.31-39
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• 1989

Although it has been well known that many metal hydrides are promising to use for hydrogen storage and other applications, some difficulties still remain. Metal hydrides, particularly in powder form, have very poor thermal conductivity. The hydrogen storage alloys degrade intrinsically or extrinsically during repeated hydriding and dehydriding. Elimination of these problems is very important in the practical applications. In order to prevent degradation and to improve the thermal conductivity, the hydrogen storage characteristics of rare-earth type alloy encapsulated with Cu or Ni by means of chemical plating have been investigated. No changes has occured in hydrogen absorption capacity and equilibrium pressure even though the alloy powder is microencapsulated. The first hydrogen absorption rate of the alloy encapsulated increased considerably comparing to uncapsulated sample. In the case of encapsulating the fine powder ($>10{\mu}m$) and subsequent compacting by $8ton/cm^2$, shape of compact is maintained regardless of hydriding and dehydriding. The degree of degradation of the alloy caused by impurity gas of CO or $O_2$ was decreased prominently by encapsulation.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.13 no.3
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• pp.241-246
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• 2000

We fabricated Bi-2223 multi-filaments superconductor tape and evaluated the effect of twisting on the microstructural evolution and critical current. Twist pitches of the tapes are in the range of 70- 8mm and uniformly deformed. It was observed that grain size and the degree of texture decreased as decreasing pitch probably due to the formation of the irregular interface between Ag and filaments. In addition critical current of the tapes decreased to 6.5 A with decreasing pitch to 8mm, showing 48% of degradation compared to the untwisted tapes decreased to 6.5 A with decreasing pitch to 8mm, showing 48% of degradation compared to the untwisted tape(12.5 A). These reduction of critical current may be related to the interface irregularity smaller grain size worse texture and the presence of cracks due to the induced strain during twisting processing.

• Journal of the Korean Society of Clothing and Textiles
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• v.29 no.3_4 s.141
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• pp.470-477
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• 2005

This study was carried out to evaluate the biodegradability of viscose rayon and lyocell fibers, employing soil burial test, activated sludge test and enzymatic hydrolysis. Using X-ray analysis, crystallinity and morphology change was investigated. External changes after degradation were also observed by SEM and digital photographs. Vscose rayon fibers exhibited higher biodegadation than lyocell fibers, indicating that lower crystallinity favored the biodegradation. Among the biodegradability of lyocell fibers there was a tendency that fibers with lower crystallinity and higher moisture regain had higher values. When external changes after degradation being observed, it was shown that there were microorganisms growing on the surfaces of samples accompanying lading and weakening. From these results it was concluded that biodegradability of the specimens was most closely correlated to the moisture regain and crystallinity of fibers which reflects hydrophilicity and internal structure.

• Membrane Journal
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• v.18 no.2
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• pp.124-131
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• 2008

The biodegradable hyaluronic acid membranes cross-linked with lactide using the crosslinking agent, 1,3-butadiene diepoxide (BD), were prepared as a potential biocompatible material for tissue engineering. The degree of lactide and BD reaction of the crosslinked membrane was determined by the analysis of nuclear magnetic resonance spectroscopy 6% of growth inhibition was observed in case of high BD concentration but the value is low enough not to affect cell growth. As the crosslinking reaction temperature increased, elongation increased and swelling ratio decreased. The rate of degradation was found to increase with the crosslinking temperature. The drug release experiment showed that the transport of drug through the membrane decreased with the crosslinking temperature.

• Journal of Soil and Groundwater Environment
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• v.21 no.6
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• pp.101-113
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• 2016

To properly manage and remediate groundwater contaminated with chlorinated hydrocarbons such as trichloroethylene (TCE), it is necessary to assess natural attenuation processes of contaminants in the aquifer along with investigation of contamination history and aquifer characterization. This study evaluated natural attenuation processes of TCE at an industrial site in Korea by delineating hydrogeochemical characteristics along the flow path of contaminated groundwater, by calculating reaction rate constants for TCE and its degradation products, and by using geochemical and reactive transport modeling. The monitoring data showed that TCE tended to be transformed to cis-1,2-dichloroethene (cis-1,2-DCE) and further to vinyl chloride (VC) via microbial reductive dechlorination, although the degree was not too significant. According to our modeling results, the temporal and spatial distribution of the TCE plume suggested the dominant role of biodegradation in attenuation processes. This study can provide a useful method for assessing natural attenuation processes in the aquifer contaminated with chlorinated hydrocarbons and can be applied to other sites with similar hydrological, microbiological, and geochemical settings.

• The Journal of the Acoustical Society of Korea
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• v.29 no.5
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• pp.347-353
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• 2010

In VoIP system, the speech quality is seriously degraded due to packet loss, and the degree of degradation by each packet loss depends on the characteristics of the corresponding packet. Therefore, it is possible to improve the speech quality of VoIP by selectively controlling the packet to be lost during transmission based on the expected degradation by the loss of each packet. In this paper, a new scheme to improve speech quality of DiffServ-based VoIP by assigning priority to each packet is proposed, and a method to determine the priority of each packet is developed. The performance of proposed method was measured in packet loss environment based on Gilbert model, and it was verified both objectively and subjectively that the speech quality is improved by the proposed method.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.4
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• pp.693-699
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• 2010

General transformer's life is known as paper insulation' life. If a transformer is degraded by these aging factors, it is known that electrical, mechanical and chemical characteristics for transformer's oil-paper are changed. When the kraft paper is aged, the cellulose polymer chains break down into shorter lengths. It causes decrease in both tensile strength and degree of polymerization of paper insulation. The paper breakdown is accompanied by an increase in the content of furanic compounds within the dielectric liquid. In this paper it is aimed at analysis on correlation between aging characteristics for insulating diagnosis of thermally aged paper. For investigating the accelerated aging process of oil-paper samples accelerating aging cell was manufactured for estimating variation of paper insulation during 500 hours at $140^{\circ}C$ temperature. To derive the results, it was performed analysis such as tensile strength(TS), depolymerization(DP), dielectric strength(DS), relative permittivity, water content(WC) and furan compound(FC) for aged paper. Also for analyzing correlation between insulating degradation characteristics, we used linear regression method. As as results of linear regression analysis, there was a close correlation between TS and DP. WC, FC. But dielectric strength was a weak correlation with aging time.

• 전기의세계
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• v.23 no.5
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• pp.54-60
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• 1974

Proposals were mode on how to differentiate radiation effects in morphological phases of polyethylene and discussions were developed with the results obtained on a low density polyethylene, SOCAREX, specified by number average molecular weight; overbar Mn=5,400, density; 0.92, and degree of branch; 3.4/100 carbon atom, which was irradiated to Co$^{60}$ .gamma. ray at the dose rate of 0.5 Mrad/hr in ambient temperature under the pressure of 10$^{-5}$ Torr. or 1 atm. respectively. The effect to crystalline phase in possibly deduced from dose dependent variation of relative area between (110) and (200) peaks on X ray diffraction spectrum and that, the effects to amorphous phase can be understood through dose dependent relaxation behaviours of .betha. peak on internal friction characteristics of the specimen. The results obtained thus far indicate that, in crystalline phase, relative crystallinity shows a rather rapid decrease up to 20 Mrad with increasing dose, however, little change of crystallinity can be observed in the region between 20-200 Mrad, and degradation appears to be more predominant than crosslinking up to 60 Mrad. While in amorphous phase the indication also shows that degradation is only predominant up to 20 Mrad. Furthermore several correlations can be seen with amenable explanation between dose dependent behaviours observed in both phases.