• Polymer(Korea)
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• 제38권4호
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• pp.510-517
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• 2014

A series of polyimide (PI) was prepared by reacting 4,4'-(hexafluoroisopropylidene)-diphthalic anhydride (6FDA) as the anhydride and bis(3-aminophenyl) sulfone (APS), bis[4-(3-aminophenoxy)-phenyl] sulfone (BAPS), 2,2-bis(4-aminophenyl)-hexafluoropropane (6FPD), 2,2-bis[4-(4-aminophenoxy)-phenyl]hexafluoropropane (6FBAPP), 2,2'-bis(trifluoromethyl)benzidine (TFDB), or 1,4-phenylenediamine (PDA) as the diamine. Residual stress behaviors were detected in-situ during thermal imidization of the polyimide precursors using a thin film stress analyzer (TFSA), and interpreted with respect to their morphology. According to the molecular orientation and packing order, the residual stress varied from 23.1 to 12.5 MPa, decreased with increasing chain rigidity. The thermal properties of the PI films were investigated using differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and thermomechanical analysis (TMA). Their optical properties were measured by ultraviolet-visible spectrophotometer (UV-vis), and spectrophotometry. The properties of PI films were found to be strongly dependent upon the morphological structure. However, trade-offs between residual stress and optical properties were identified.

• Applied Biological Chemistry
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• 제24권2호
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• pp.126-131
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• 1981

General composition, amines, and flesh tissue of boiled-dryed abalone and sea cucumber were compared with those of the freeze-dried abalone and sea cucumber. No significant differences were found in the general composition between the boiled-dried and freeze-dried, but the slight amount of soup flowed out from the boiled-dried. A specific feature is that 28.24% of ash was found in the boild-dried sea cucumber and 33.99% of ash in the freeze dried one in order of Na, K, Mg, Ca. Such contents of ash are considered to be due to salt and soft bone of samples. In the changes of amines in abalone and sea cucumber, trimethylamine oxide (TMAO) showed no great difference between raw samples and the dried ones, but showed the decrease of 43% to 54% in the boiled-dried ones, compared with raw ones. Trimethylamine (TMA) was richer in the boiled-dried than in the dried. Dimethylamine (DMA) which has tendency of causing cancer in the human body showed 14 times of content in the freeze boiled-dried abalone, 18.5 times in the boiled-dried sea cu cumber and also showed 4.7 to 6.7 times of increase in the freeze dried, respectively compared with raw ones. The muscular change of abalone was not found in at freeze dried samples, but a considerable change in sea cucumber.

• Membrane Journal
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• 제14권2호
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• pp.108-116
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• 2004

In this study, the pore-filled ion-exchange membranes were prepared by using the asymmetric PVDF membrane as a nascent membrane. First, the solution of PVBCI having the chlorornethylate aryl ring of 80 percents and DABCO was made with the mixed solvent of THF and DU (8:2). These mixed solution was then, filled in the pores of PVDF membrane, and left for a day to complete the gelation. Finally the pore-filled anion-exchange membrane is obtained fallowed by the amination of the remaining chloromethyl groups with trimethylamine (TMA, 40 wt% in water) forming the positive ammonium ion sites. This 2 step procedure enabled us to produce the pore-filled membranes without change of size, and to control the properties of final membrane with various degree of cross-linking. The results of SEM and AFM showed the polyelectrolyte existed in the pores of nascent membrane as a certain configuration. From the investigation of the solvent affecting much to the permeability and rejection, it was found that the membranes using mixed solvent of THE and DMF (8:2) showed better performances than the membranes produced by THF only. The result of an investigation for the water permeability of the final membrane at low pressure (100 Kpa) showed a typical ultrafiltration membrane's permeability (8 ∼ 10 kg/$m^2$hr) and good values of rejection (55∼60 percent).

• Journal of the Mineralogical Society of Korea
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• 제17권1호
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• pp.49-59
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• 2004

Organic smectite was hydrothermally synthesized by treating the opal-rich siliceous mudstone from the Pohang area with TMAOH solutions and 1:1 solutions of TMAOH+NaOH at $80^{\circ}C$ and concentrations ranging 10∼15%. Smectite was solely formed without accompanying any mineral products in case of TMAOH, whereas NaP and hydroxysodalite was synthesized together with smectite under the blending solution of TMAOH+NaOH. The synthesized smectite is identified as an organic smectite intercalating $TMA^{+}$ within its interlayer site, specifically corresponding to monmorillonite species, through mineralogical characterization by XRD, DTA, and IR analyses. The experimental results indicate that main precursor of the synthesized smectite is undoubtedly opal-CT, and the original sedimentary smectite included as considerable amounts in the mudstone seems to play a major role as Al-sources necessary far the smectite formation. Original inert components such as quartz and mica do not affect mostly to the synthesis reaction, and thus, are resultantly found as impurities in the synthetic products. These experimental results may imply that a new effective method for the low-temperature (less than $100^{\circ}C$) hydrothermal synthesis of organic smectite will be established if some Al-sources adequate for this synthetic system are available.

• Journal of the Korean Society of Food Science and Nutrition
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• 제40권1호
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• pp.94-101
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• 2011

Squid (Todarodes pacificus) is processed as dried or seasoned-dried products and its catch gradually increased from 270,298 M/T in 2005 to 367,940 M/T in 2008 in Korea. Squid processing by-product (viscera) was usually discarded as a waste resulting in environmental problem. In order to utilize squid viscera for more value-added products, a natural squid seasoning was developed by fermenting with Aspergillus oryzae koji. Squid viscera at 5, 10 and 15% salt concentrations with fixed levels of 5% koji and 30% water was fermented at room temperature. The quality properties of squid fermented products such as amino-N, TMA, VBN, total viable cell count, pH and total acidity were determined at different fermentation periods. The contents of amino-N, TMA, and VBN of squid seasoning at 5% salt concentration fermented for 14 days were the highest. Based on amino-N content, squid viscera at 5% koji fermented for 14 days was selected for further assays: the content of moisture, crude protein, crude lipid, crude ash, and carbohydrate were 5.98, 35.19, 33.08, 11.30, and 14.45%, respectively. The content of glutamate, alanine, leusine and lysine were 7.06, 12.34, 9.90 and 10.22%, respectively. The $IC_{50}$ values of DPPH scavenging and $\beta$-glucuronidase inhibitory activity were 12.89 and 12.58 mg/mL, respectively. A natural squid seasoning was manufactured by mixing fermented squid viscera and an ingredient. Based on the results of sensory evaluation, the fermented squid viscera seasoning was almost equal to other natural complex seasonings such as anchovy, cow meat, and fisheries seasoning.

• Korean Journal of Food Science and Technology
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• 제28권4호
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• pp.696-701
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• 1996

For effective utilization of skipjack (Katsuwonus pelamis) cooking juice (SCJ), the SCJ was hydrolyzed with 0.5% neutrase at $50^{\circ}C$ for 1 hr, and the degree of hydrolysis was estimated to be 66.0% at this reaction condition. The hydrolysate was treated with charcoal and filtered under reduced pressure. The extract powder was prepared from the filtrate in a spray-dryer. The major free amino acids of the extract Powder were taurine (526.3 mg/100 g), glutamic acid (375.8 mg/100 g), phenylalanine (315.9 mg/100 g), and alanine (283.6 mg/100 g), and their content accounted for 55.4% of the total free amino acids (2,711.5 mg/100 g). Among the nucleotides and their related compounds, inosine was the major component with 76.29 mole/g. The content of betaine-N, total ceatinine-N, TMAO-N, and TMA-N were 72.2, 51.2, 10.3, and 6.9 mg/100 g, respectively. From the omission test, it was concluded that the major taste compounds of the extract powder were believed to be free amino acids such as glutamic acid and alanine. Organic acids and nucleotides and their related compounds acted an auxiliary role in the taste of the extract powder.

• Proceedings of the Microbiological Society of Korea Conference
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• 한국미생물학회 1991년도 춘계학술발표대회 논문집
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• pp.225-236
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• 1991

The genes encoding the thermostable $\alpha$-amylase and maltogenic amylase from Bacillus lichenciformis were cloned and expressed in E. coli. The recombinant plasmid pTA322 was found to contain a 3.1kb EcoRI genomic DNA fragment of the thermostable $\alpha$-amylase. The cloned $\alpha$-amylase was compared with the B. licheniformis native $\alpha$-amylase. Both $\alpha$-amylase have the same optimal temperature of $70^{\circ}C$ and are stable in the pH range of 6 and 9. The complete nucleotide sequences of the thermostable $\alpha$-amylase gene were determined. It was composed of one open reading rame of 1,536 bp. Start and stop codons are ATG and TAG. From the amino acid sequence deduced from the nucleotide sequence, the cloned thermostable $\alpha$-amylase is composed of 483 amino acid residues and its molecular weight is 55,200 daltons. The content of guanine and cytosine is $47.46mol\%$ and that of third base codon was $53_41mol\%$. The recombinant plasmid, pIJ322 encoding the maltogenic amylase contains a 3.5kb EcoRI-BamHI genomic DNA fragment. The optimal reaction temperature and pH of the maltogenci amylase were $50^{\circ}C$ and 7, respectively. The maltogenic amylase was capable of hydrolysing pullulan, starch and cyclodextrin to produce maltose from starch and panose from pullulan. The maltogenic amylase also showed the transferring activity. The maltogenic amylase gene is composed of one open reading frame of 1,734bp. Start and stop codons are ATG and ATG. At 2bp upstream from start codon, the nucleotide sequence AAAGGGGGAA seems to be the ribosome-binding site(RBS, Shine-Dalgarno sequence). A putative promoter(-35 and-10 regions) was found to be GTTAACA and TGATAAT. From deduced amino acid sequence from the nucleotide srquence, this enzyme was comosed of 578 amino acid residues and its molecular weight was 77,233 daltons. The content of guanine and cytosine was $48.1mol\%$. The new recombinant plasmid, pTMA322 constructed by inserting the thermostable $\alpha$-amylase gene in the EcoRI site of pIJ322 to produce both the thermostable $\alpha$-amylase and the maltogenic amylase were expressed in the E. coli. The two enzymes expressed from E. coli containing pTMA322 was reacted with the $15\%$ starch slurry at $40^{\circ}C$ for 24hours. The distribution of the branched oligosaccharides produced by the single-step process was of the ratio 50 : 50 between small oligosaccharide up DP3 and large oligosaccharide above DP3.

• Korean Journal of Food Science and Technology
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• 제42권4호
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• pp.438-444
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• 2010

Fermented skate has a unique ammonia-like flavor. The flavor is preferred by a few lovers of skate muscle, while women and young people may be sensitive to the odor. Organic acids were used to reduce the ammonia-like odor in fermented skate and to investigate the physicochemical properties. Fermented skate muscles were sprayed with 20 mL of acetic acid or citric acid (3, 5, and 7%) for 30 seconds and stored at $4^{\circ}C$ for 15 days. The physicochemical properties of organic acid-treated fermented skate were investigated during storage. The control, which was treated with distilled water, showed a higher pH value than the samples treated with organic acids. The $L^*$ value increased with increasing organic acid concentration, while the $a^*$ and $b^*$ values were not significantly different among the samples. The trimethylamine (TMA) decreased with increasing in the organic acid concentration, but it was not significantly different after 9 days of storage. Ammonia-type nitrogen and ammonia-like flavoring, decreased with increasing in the organic acid concentration, whereas ammonia-type nitrogen increased with a storage period more than 6 days. In conclusion, fermented skate treated with 7% citric acid was the best treatment to reduce the ammonia-like odor.

• Journal of the Korean Society of Food Culture
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• 제19권5호
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• pp.516-523
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• 2004

This study was conducted to investigate the changes in the qualify of gamma-irradiated seasoned cuttle during storage. Seasoned cuttle packed in PVC film (0.06 win) was stored at $15{\pm}1^{\circ}C$ for 6 months after treatment with doses of 0 to 7 kGy. Microbial populations of seasoned cuttle were $1.6{\times}10^{5}CFU/g$ in total aerobic bacteria, $10^{4}{\sim}10^{5}CFU/g$ in yeasts &molds, and negative in coliforms, which were effectively reduced by 3 kCy or higher up to the undetectable level(<20 CFU/g). The pH and moisture content of the samples were not changed with irradiation, but moisture was some decreased during storage. The instrumental color (especially Hunter b value), pigments (lipophilic &hydrophilic) and TBA value of the samples increased with storage time as well as irradiation dose more than 3 kGy. The influence of storage condition, however, were more significant. Irradiation did not induce any changes in volatile basic nitrogen (VBN) and trimethylamine (TMA) contents, thereby maintaining their contents lower than those of the non-irradiated samples during storage by reducing the microbial load.

• Korean journal of food and cookery science
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• 제2권1호
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• pp.38-44
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• 1986

Effects of the kind and concentration of salt on oxidation of lipids and on formation of flavor components have been studied with four varieties of fermented anchovies prepared with 20％ sun-dried salt(sample B) , 12% refined salt (sample C), 16.5％ refined salt (sample D) and 16. 5% refined salt Plus 25％ brine (sample E). The sample B showed higher peroxide and TBA value and also higher content of TMA thar. those prepared with refined salt. The amounts of amino-N and VBN in sample B appeared larger than in sample D but was in a similar level with those in sample C. On the other hands, much smaller amounts of lactic and succinic acid were observed in sample B compared with in sample C and D. Sample C revealed the highest level of lactic acid among the samples tested. The changes in the amounts of each free amino acid displayed similar tendencies in all samples, except decreasing tendency of tyrosine in sample B and increasing tendency of aspartic acid in sample C. Also observed was lower IMP and inosine level in sample B than in C and D, but hypox-anthine level was higher in B. In general, sample I indicated remarkably lower values of experimental data in all cases mentioned above, but the highest TBA balue.