• Journal of electromagnetic engineering and science
• /
• v.5 no.2
• /
• pp.49-60
• /
• 2005

In this paper, an efficient performance enhancement scheme for an adaptive antenna array under the flat and the frequency-selective Rayleigh fadings is proposed. The proposed signal enhancement scheme is the modified linear signal estimator which combines the rank N approximation by reducing noise eigenvalues(RANE) and Toeplitz matrix approximation(TMA) methods into the linear signal estimator. The proposed performance enhancement scheme is performed by not only reducing the noise component from the signal-plus-noise subspace using RANE but also having the theoretical property of noise-free signal using TMA. Consequently, the key idea of the proposed performance enhancement scheme is to greatly enhance the performance of an adaptive antenna array by removing all undesired noise effects from the post-correlation received signal. The proposed performance enhancement scheme applies at the Wiener maximal ratio combining(MRC) method which has been widely used as the conventional adaptive antenna array. It is shown through several simulation results that the performance of an adaptive antenna array using the proposed signal enhancement scheme is much superior to that of a system using the conventional method under several environments, i.e., a flat Rayleigh fading, a fast frequency-selective Rayleigh fading, a perfect/imperfect power control, a single cell, and a multicell.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.25 no.6
• /
• pp.932-936
• /
• 1996

Scallop, Pectinopecten yessoenis(Jay), cultivated in the cold east coast of Kwangwon region, Korea, is expected be to produced about 50, 000 tons in the year 2000. Scallop, first of all should be exuviated to process for new goods. In this study, vacuum and nitrogen packagings were applied to extend the shelf-life of exuviated scallop boiled with steam for 10 min. Vacuum and nitrogen packagings retarded the decrease in pH, whereas inhibited the production of $NH_2-N, $ VBN, TMA, and TBA of exuviated scallop stored at $5^{\circ}C.$ They also inhibited the microbial growth. But, there was no significant difference in the bacteriostatic effects between both packaging methods. The estimated shelf-lives of boiled and exuviated scallops for control, vacuum, and nitrogen packagings were about 30, 36, and 36 days, respectively.

• Journal of IKEEE
• /
• v.11 no.4
• /
• pp.235-238
• /
• 2007

The planar edge termination techniques of field-ring and deep junction field-ring were investigated and optimized using a two-dimensional device simulator TMA MEDICI. By trenching the field ring site which would be implanted, a better blocking capability can be obtained. The results show that the p-n junction with deep junction field-ring can accomplish near 30% increase of breakdown voltage in comparison with the conventional field-rings. The deep junctionfield-rings are easy to design and fabricate and consume same area but they are relatively sensitive to surface charge. Extensive device simulations as well as qualitative analyses confirm these conclusions.

• Korean Journal of Food Science and Technology
• /
• v.15 no.1
• /
• pp.1-5
• /
• 1983

Large quantities of an ascidian, Styela plicata, are harvested annually as the by-product of oyster culture on the south coastal area in Korea. It has been traditionally favored and consumed because of its peculiar taste and flavor. But no study on its taste compounds has been reported. An investigation on the taste compounds of fresh meat and integument of an ascidian has been carried out by a series of analysis of taste compounds including nucleotides, free amino acids, betaine, TMAO, TMA and total creatinine. The most abundant nucleotides in fresh meat were AMP and IMP. Their contents were $1.2\;and\;0.8{\mu}mole/g$, respectively. The contents of nucleotides and their related compounds in integument show similar tendency as in fresh meat but their quantities were very low as compared with those in fresh meat. Seventy two percentage of the total free amino acids in fresh meat was consisted of proline, alanine, glutamic acid, glycine and serine. They occupied also 82% of the total free amino acids in integument, but the amount of free amino acids in integument was about 1/10 of that in fresh meat. The contents of betaine-N and creatinine-N were 6.1 and 2.1% of the extractive-N in fresh meat, respectively. The amounts of TMAO-N and TMA-N were very low contents in fresh meat and trace in integument.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.19 no.1
• /
• pp.35.2-72
• /
• 1990

N-Nitrosamines have been known to be strong carcinogens and are formed by the reaction of nitrous acid with amines. In this experiment the changes in the contents of nitrate nitrite trimethylaminoxide(TMAO) trimethylamine(TMA) and dimethylamine(DMA) during femen-tation of damsel fish were analyzed periodically and N-nitrosamines in a commercial products. N-Nitrosamines were determined by mineral oil distillation methods using gas chromatography-thermal energy anlyzer(GC-TEA) in a commerical product. Nitrate nitrite and amines were quantitate by colorimetric methods. Level of nitrate-N were gradually decreased but nitrite-n was not detected or trace. Contents of dimethlamine(DMA) and trimethlamine were mar-kedly increased while trimethylaminoxide nitrogen was decreased during the fermentation of damsel fish. The change of pH was in the ranges of 5,5-7.0 during fermentation of salted damsel fish. It was out of the optimum pH(3.0-3.4) for the formation of nitrosamine. N-Nitrosamines were not detected in salt-fermented damsel fist but much N-nitrosodimethyla-mine(NDMA) could be detected in salt-fermented damsel fish after adding 0.05M NaNo2 in the acidic condition. The identifaction of NDMA in it was confirmed by mass spectrophotometry. Nitrate decrea-sed during the fermentation of damsel fish. however nitrite was trace level and nitrosamines were not formed in its. This could be supposed that it was due to the rapid consumption of nitrite by amino acid and bacteria.

• The Korean Journal of Physiology and Pharmacology
• /
• v.8 no.4
• /
• pp.213-218
• /
• 2004

Primary fish-odor syndrome (FOS) is a genetic disorder caused by defective flavin-containing mono-oxygenase 3 gene (FMO3) with deficient N-oxidation of trimethylamine (TMA), causing trimethylaminuria (TMAU). By contrast, secondary FOS can be acquired by decreased FMO activities in patients with chronic liver diseases, but the underlying mechanisms are unknown. In the present study, we examined plasma NOx concentrations and viral DNA contents as well as in vivo FMO activities and their correlations in chronic viral hepatitis (CVH) patients. Plasma concentration of NOx was significantly increased by 2.1 fold $(56.2{\pm}26.5\;vs.\;26.6{\pm}5.4\;{\mu}M,\;p<0.01)$, and it was positively correlated with plasma hepatitis B virus (HBV) DNA contents $(r^2=0.2838,\;p=0.0107)$. Furthermore, the elevated plasma NOx values were inversely and significantly correlated with in vivo FMO activities detected by ranitidine-challenged test $(8.3%\;vs.\;20.0%,\;r^2=0.2109,\;p=\0.0315)$. TMA N-oxidation activities determined in CVH patients without challenge test were also significantly low (73.6% vs. 95.7%, p< 0.05). In conclusion, these results suggested that secondary FOS could be acquired by the endogenously elevated NO in patients with CVH.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.52 no.6
• /
• pp.735-739
• /
• 2019

The purpose of this study was to measure pH, trimethylamine (TMA), and total volatile basic nitrogen (TVB-N) as indicators of freshness during largehead hairtail Trichiurus lepturus storage, and to compare these indicators with those obtained by the sensory evaluation of quality index method (QIM) sensory evaluation. Largehead hairtail samples were stored at 4℃ and evaluated every 3 days until decay. The QIM sensory evaluation indicated scores of 0, 8.9, and 20 on storage days 0, 6, and 20, respectively. By day 15, the samples were completely decayed. The pH slowly increased during the storage period, reaching a maximum of 7.4. In the day 6, TMA and TVB-N contents were 2.97 and 15.57 mg/100 g, respectively. Thus, at 4℃, the largehead hairtail starts to decay after 6 days and, after 9 days, cannot be consumed safely

• Journal of Magnetics
• /
• v.1 no.1
• /
• pp.19-23
• /
• 1996

In the present study, the $Sm_2Fe_{17}N_x$-type interstitial materials have been prepared by reaction between Nb-free or Nb-containing $Sm_2Fe_{17}$-type alloy and $N_2$ gas. Nitrogenation behaviour of the $Sm_2Fe_{17}N_x$-type material and disproportionation characteristics of the nitrogenated materials have been studied by means of differential thermal analysis (DTA) and thermopiezic analysis (TPA). Magnetic properties of the produced $Sm_2Fe_{17}N_x$-type interstitial materials were characterised in vibrating sample magnetometer (VSM) or thermomagnetic analyser (TMA). Epoxy-bonded or Zn-bonded $Sm_2Fe_{17}N_x$-type magnets were prepared, and their magnetic properties were investigated. It has been found that nitrogenation kinetics of the Sm2Fe17Nx-type alloy is improved significantly by the Nb-substitution for Fe in the alloy. The Nb-substitution is also found to enhance thermal stability of the $Sm_2Fe_{17}N_x$-type interstitial material. Hard magnetic properties of the interstitial materials produced from Nb-free orNb-containing alloy is high enough (intrinsic coercivity : over 7 kOe) for application as bonded permanent magnets. The good hard magnetic properties of the interstitial material are maintained in the epoxy-bonded magnet. Intrinsic coercivity of the Zn-bonded magnets is improved significantly as post-bonding annealing time increases.

• Membrane Journal
• /
• v.20 no.2
• /
• pp.142-150
• /
• 2010

A series of anion exchange composite membranes were prepared and characterized for electrodialysis processes used in the removal of nitrate nitrogen and ions in groundwater. The membranes were prepared as follows; first, fabric substrates were fully impregnated with monomer mixtures of vinylbenzylchloride (VBC), divinylbenzene (DVB), Styrene (ST) and $\alpha,\alpha$-Azobis(isobutyronitrile) (AIBN). Second, they were thermally polymerized to yield crosslinked poly (VBCST- DVB)/fabric composite membranes. Finally, the membranes were treated with trimethylamine (TMA) / acetone to give $-N^+(CH_3)_3^-$-containing poly(VBC-ST-DVB)/fabric membranes. The basic membrane properties such as ion exchange capacity (IEC), electric resistance and water content of the resulting membranes were measured as a function of VBC/DVB and TMA/Acetone content. As a result, the composite membranes showed lower electric resistance and higher IEC than commercial anion exchange membranes (AMX, Astom). Electrodialysis tests using the prepared membranes were carried out for the removal of various ions such as $NaNO_3$, $MgSO_4$ and NaF for 60 minutes. The results showed that the ions were removed below 1 mg/L within about 15 minutes which indicates that the anion exchange membranes prepared here could be applied to the electrodialysis process. as can be seen in the following that the ion conductivity values were almost no change after 15 minutes electrodialysis.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.16 no.3
• /
• pp.231-238
• /
• 1983

An investigation on optimum condition for processing of salted-dried sardine and quality change of the product during the storage was carried out. The fillets of sardine were salted in 5, 10 and $15\%$ NaCl solution for 12, 24 and 36 hours at $9-10^{\circ}C$, respectively and air-blast dried at $24-25^{\circ}C$ with a velocity of 3 m/sec and then stored at room temperature for 30 days. The results were as follows : The optimum condition for the product was salting in $15\%$ NaCl solution for 36 hours as VBN and histamine contents were 27.5 mg/100g and 42.5 mg/100g, respectively, and also showed a good result in sensory evaluation. Histamine, VBN and TMA-N content of the dried fillets immediately after salting in $15\%$ NaCl solution for 36 hours increased to 47.8 mg, 29.5 mg and 5.4mg per 100g of the sample, respectively and increased slowly during the storage. The peroxide value and acid value of the lipid extracted from the product increased from 15.9 meq/kg to 114.0 meq/kg, and 12.6 to 30.5 during the storage. In the fatty acid composition, $C_{22:6}\;and\;C_{20:5}$ acids were decreased during the storage period.