• Journal of the Korean Society of Food Science and Nutrition
• /
• v.22 no.2
• /
• pp.246-252
• /
• 1993

Melanoidins, as brown colored polymers, are formed through the diversified reaction systems of Maillard type and other reactions. Melanoidins are important components in relation to food quality and also are known to have antioxidative, mutagenic and antimutagenic activities. Since these aspects have been extensively reviwed elsewhere, only the recent studies regarding to their antioxidative and antimutagenic activities are discussed in this review. Even though their mechanisms are not clearly identified, melanoidins or specific fractions isolated from their mixtures have shown varied antioxidative activities depending on the reaction systems and reaction conditions. Those activities presumely are derived from the complex functional properties of hydrogen / electron donors and metal chelating power, which are originated from their reductone structure and others. It is considered that pyrolysate and other mutagens are formed by the given conditions in some cases during browning reaction, whereas melanoidins and their fractions have antimutagenic effects on chemical and other mutagens. There are positive correlationship among the color intensity, antioxidative activity and antimutagenicity of melanoidins or their fractions. These suggest that the antimutagenicity of melanoidins could be attributed to their antioxidative properties, however, it might also be due to other factors, because the relevant responses for antimutagenicity are very complicate and not clear. Accordingly, further studies are required to determine the actual acitivities and mechanisms involved in antioxidation and (anti)mutagenicity of melanoidins by reaction systems / conditions and by the isolated fractions. And also, additional studies are needed to evaluate the applications of melanoidins and their relevant effects to food and human health.

• Journal of the Korean Institute of Intelligent Systems
• /
• v.16 no.6
• /
• pp.677-682
• /
• 2006

Multi-domain design is difficult because such systems tend to be complex and include a mixtures of electrical, mechanical, hydraulic, and thermal components. To design an optimal system, unified and automated procedure with efficient search technique is required. This paper introduces design method for multi-domain system to obtain design solutions automatically, combining bond graph which is domain independent modeling tool and genetic programming which is well recognized as a powerful tool for open-ended search. The suggested design methodology has been applied for design of electric fitter, electric printer drive, and and pump system as a proof of concept for this approach.

• Geomechanics and Engineering
• /
• v.31 no.6
• /
• pp. 583-597
• /
• 2022

Frost heave can cause uneven ground uplift that may damage geo-infrastructure. To assist damage-prevention strategies, standard frost heave testing methods and frost susceptibility criteria have been established and used in various countries. ASTM International standard testing method is potentially the most useful standard, as abundant experimental data have been acquired through its use. ASTM International provides detailed recommendations, but the method is expensive and laborious because of the complex testing procedure requiring a freezing chamber. A simple frost heave testing method using a temperature-controllable cell has been proposed to overcome these difficulties, but it has not yet been established whether a temperature-controllable cell can adequately replace the ASTM International recommended apparatus. This paper reviews the applicability of the ASTM International testing method using the temperature-controllable cell. Freezing tests are compared using various soil mixtures with and without delivering blow to depress the freezing point (as recommended by ASTM International), and it is established that delivering blow does not affect heave rate, which is the key parameter in successful characterization of frost susceptibility. As the freezing temperature decreases, the duration of supercooling of pore water shortens or is eliminated; i.e., thermal shock with a sufficiently low freezing temperature can minimize or possibly eliminate supercooling.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.16 no.2
• /
• pp.125-132
• /
• 1983

Dielectric properties of sardine-starch paste with moisture content of 4 to $13\%$ were investigated as functions of moisture and frequency. And the effects of the levels of fat and starch of the mixtures upon dielectric permittivity, critical moisture, were also mentioned. In addition, a theoretical prediction of frequency dependence of dielectric constant which was computed by the lumped circuit of two layer condenser model was evaluated. For the preparation of sardine-starch paste, comminuted sardine meat was washed thoroughly several times in chilled water by soaking and decanting, and finally centrifuged. This procedure was extended longer to provide a low fat sample. The centrifuged meat was mixed with adequate amounts of starch and salt, and ground for 25 minutes in a stone mortar, moulded in the form of disk with 7cm diameter and 1.2cm thickness and then freeze dried. Dried meat disks were cut off for the size of 5.5cm diameter and 1.0cm thickness and their moisture contents were controlled in humidified desiccators with saturated solutions. Dielectric constants of sardine-starch paste tended to decrease frequency was increased showing a critical charge at the moisture called critical moisture content. In case of the sample with $20\%$ starch and $2\%$ salt an average complex permittivity($\epsilon^{\ast}$) at 7 to $8\%$ morsture as the critical moisture content was presented; $\epsilon^{\ast}$=3.37+j 0.39 at 0.1 MHz, $\epsilon^{\ast}$=2.54+j 0.19 at 15 MHz, and $\epsilon^{\ast}$=2.15+j 0.08 at 1.8 GHz, respectively. The theoretically obtained complex permittivity values from the two layer condoner model were in close agreement with these actual measurements under the same conditions, that appeared as $\epsilon^{\ast}$=2.53+i 0.09 at 0.1 MHz and $\epsilon^{\ast}$=2.28+j 0.06 at 15 MHz, respectively. The fast level of the mixture also revealed an influence on dielectric property that defatted neat with $1.0\%$ fat showed a higher hc and $\epsilon^{\ast}$ value than the meat with $4.8\%$ fat. Complex permittivity being related to the moisture level remained nearly unchanged or slightly changed at the moisture range of 4 to $8\%$ but was dispersed widely at higher moisture contents.

• Journal of the Korean Chemical Society
• /
• v.29 no.5
• /
• pp.472-477
• /
• 1985

The rates for the aquation of $cis-[Co(en)(NH_3)_2Cl_2]Cl in acetone-water mixtures have been measured at various pressures and temperatures by the electric conductivity method. The rate constant measured at 25$^{\circ}$C in pure water solvent is 3.47 ${\times}10^{-4}$/sec. Rate constants are increased with increasing temperature, and decreased with increasing pressure and mole fraction of acetone. Activation volumes and other activation parameters are calculated from these rate constants. The activation volumes are all positive and lie in the limited range +2.82~+$8.2cm^3$/mole. The rate constants in aqueous acetone solution are analyzed with the solvent compositions. Plots of log $k_{obs}$ vs. Grunwald-Winstein Y values show that log $k_{obs}$ varies linearly and the gradients are about 0.25. The applications of a free energy cycle relating the process initial state ${\to}$ transition state in water to that in acetone-water mixture show that the changes in solvation of the transition state have a dominant effect on the rate. From these results the aquation of this complex would be discussed in terms of dissociative mechanism ($I_d$).

• Journal of Pharmaceutical Investigation
• /
• v.26 no.1
• /
• pp.1-11
• /
• 1996

Biphenyldimethyldicarboxylate (PMC), which has been used to treat hepatitis, is insoluble in water, therefore it has low bioavailability after oral administration. For the purpose of increasing the dissolution rate of PMC, the physical mixtures and inclusion complexes of PMC and $dimethyl-{\beta}-cyclodextrin\;(DM\;{\beta}CD)\;or\;hydroxypropyl-{\beta}-cyclodextrin\;(HP{\beta}CD)$ in molar ratio of 1 : 1 and 1 : 2 were prepared by solvent evaporation method. Mixed micelles of PMC were prepared by reacting PMC with bile salts [sodium cholate(NaC), sodium glycocholate (NaGC)] and oleic acid (OA) or palmitoylcarnitine chloride(PCC). Chloroform/water partition coefficient (PC) of PMC was 36.14 in artificial gastric juice (AGJ) and 33.47 in artificial intestinal juice (AIJ), respectively, on the other hand octanol/water PC was 63.36. PMC formulation was prepared by reacting PMC with PEG400-glycerin system(95 : 5, 90 : 10, respectively) and PEG400-PEG4000-glycerin system (70 : 25 : 5, 65 : 25 : 10, respectively). Dissolution test was performed in AGJ and AIJ by paddle method at $37{\pm}0.5^{\circ}C$. The dissolution rates of PMC tablets on the market were 5.74% and 8.26% at AGJ and AIJ, respectively and marketed PMC capsules were 22.14% and 28.64% at AGJ and AIJ, respectively. The dissolution rates of inclusion complexes of PMC with $DM{\beta}CD$ and $HP{\beta}CD$ in a molar ratio of 1 : 1 were more fast than those of corresponding physical mixtures. The decreasing order of dissolution rates was as follows; PMC-PEG400-PEG4000-glycerin formulation > PMC-PEG400-glycerin formulation > mixed micelles > CD inclusion complexes. The dissolution rates of PMC-PEG400-glycerin and PMC-PEG400-PEG4000-glycerin formulation were most fast and the percentage of dissolution was almost 100% within 20 minutes. And their dissolution rates after 120 minutes were markedly increased as compared with capsules on the market (4.0-fold and 3.2-fold in PMC-PEG400-glycerin formulation at AGJ and AIJ, respectively, and 4.8-fold and 3.7-fold in PMC-PEG400-PEG4000-glycerin formulation at AGJ and AIJ, respectively).

• Journal of the Korean Society of Tobacco Science
• /
• v.13 no.1
• /
• pp.19-26
• /
• 1991

Ames test using special strains which are histidine requiring mutant of Salmonella typhimufium , is widely utilized as short-term bioassay to evaluate the genotoxicity of chemicals. This method requires the liver microsome(5-9 fraction) to provide mammalian metabolism of the compounds, Therefore, the mutagenic potency of the chemicals is affected by not only the intrinsic properties of them but also the efficiency of the in vitro microsomal activation system. For this reason, the complex mixtures such as environmental pollutants from occupational sources, natural products or cigarette smoke condensates(CSC) , might be often appeared the false results. Induction of sister chromatid exchange(SCE) in cultured cells is known as another sensitive and powerful tool for the measurement of genotoxicity and the method has also an advantage which is able to apply to the in vitro and in vivo systems. In the present study, the inducibilities of revertant colonies in tester strain TA98 and SCE in human Iymphocytes by positive controls and total particulated materials(TPM) obtained from various brand(domastic and imported) cigarettes were compared in order to investigate whether the results in Ames test are in agreement with those in SCE analysis. The mutagenic activities of well known mutagens such as B(a)P showed excellent dose-response in the both methods although the induction mechanism was different each other, but cyclophosphamide resulted such effect only in SCE analysis. Most TPM tested showed a similar pattern in the mutagenic activities in those methods. However, only two(one imported brand and one domestic sample cigarettes) among the TMP obtained from various cigarettes appeared the higher induction in SCE than Ames test.

• Macromolecular Research
• /
• v.12 no.2
• /
• pp.195-205
• /
• 2004

We have synthesized new aromatic polyesters (DiPEG-HQ and DiPEG-BP) by condensation polymerization of a terephthalic acid derivative bearing a pendant oligo(oxyethylene) (DP = 7, MW = 350), which has a methoxy terminal group, and two different aromatic diols, hydroquinone and 4,4'-biphenoI. The synthesized polymers were characterized by differential scanning calorimetry (DSC), polarizing microscopy, and X-ray diffractometry for their liquid crystallinity (LC), thermal transitions, and structural morphologies in mesophases. The morphology of the LC phases depends strongly on the length of the rigid backbone repeating unit. The DiPEG-BP polymer having a longer repeating unit exhibits both layered and nematic structures before isotropization, whereas the DiPEG-HQ polymer having a shorter repeating unit shows only the layered structure in the mesophase. We found that the layer spacing for DiPEG-HQ is larger than that for DiPEG-BP. Both polymers easily form complexes with LiCF$_3$SO$_3$; we studied this complex formation by FT-IR spectroscopy. The layer spacing of the polymer-electrolyte composites increases upon increasing the amount of the lithium salt. The polymer/salt electrolyte mixtures we investigated at molar ratios of EO:salt in the range of 5-20 exhibit electrical conductivity values at 40$^{\circ}C$ of 2.4${\times}$10$\^$5/ and 1.1${\times}$10$\^$－5/ S/cm for DiPEG-HQ/LiCF$_3$SO$_3$ and DiPEG-BP/LiCF$_3$SO$_3$, respectively. At 80 $^{\circ}C$, these values are higher: 4.6${\times}$10$\^$－3/ and 1.1${\times}$10$\^$－4/ S/cm, respectively. The activation energy of conductivity depends strongly on the salt concentration.

• International Journal of Highway Engineering
• /
• v.20 no.3
• /
• pp.47-57
• /
• 2018

PURPOSES : The permeable pavement type has been rapidly developed for solving problems regarding traffic noise in the area of housing complex and heavy rainwater drainage in order to account for the climate change. In this regards, the objective of this study is to figure out the characteristics of pavement types. METHODS : The laboratory test for deriving optimum asphalt content (OAC) was conducted using the mixtures of the permeable asphalt surface for the pavement surface from Marshall compaction method. Based on its results, the pavement construction at the test field was conducted. After that, the site performance tests for measuring the traffic noise, strength and permeability were carried out for the relative evaluation in 2 months after the traffic opening. The specific site tests are noble close proximity method (NCPX), Light falling deflectometer test (LFWD) and the compact permeability test. RESULTS : The ordered highest values of the traffic noise level can be found such as normal dense graded asphalt, drainage and porous structure types. In the results from LFWD, the strength values of the porous and drainage asphalt types had been lower, but the strength of normal asphalt structure had relatively stayed high. CONCLUSIONS :The porous structure has been shown to perform significantly better in permeability and noise reduction than others. In addition to this study, the evaluation of the properties and the determination of the optimum thickness for the subgrade course under the porous pavement will be conducted using ground investigation technique in the further research.

• The Korean Journal of Malacology
• /
• v.26 no.1
• /
• pp.1-18
• /
• 2010

Biological organisms produce organic-inorganic nanocomposite composites that are hierarchically organized in composition and microstructure, containing both inorganic and organic components in complicated mixtures. The process related to the generation and regeneration of organic-inorganic complex in nature is called biomineralization process. Understanding how the process operates in a biological environment is a valuable guide to the synthesis of novel advanced material and developing important industrial processes. Like the mechanism of organisms, mollusks were also synthesized from interaction between organic matrices and minerals and their morphology was designed through biomineralization. In this study, shell formation has been studied as a bio-model and the application of biomimetics based on biomineralization is focused.