• Korean Journal of Fisheries and Aquatic Sciences
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• v.27 no.3
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• pp.247-258
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• 1994

A total of 31 commercial dried marine food products, consisting of 14 fishes, 2 shellfishes and 2 seaweeds species were analyzed for their contents of precusors of N-nitrosamine such as dimethylamine(DMA), trimethylamine(TMA), trimethylamine oxide (TMAO), betaine and nitrate and nitrite nitrogen as factors of N-nitrosamine formation. Carcinogenic N-nitrosamines were extracted by a steam distillation apparatus and were analyzed for their components using a gas chromatography-thermal energy analyzer. N-nitrosodimethylamine(NDMA) was confirmed by a gas chromatography-mass spectrometry. The contents of betaine nitrogen in samples were in the range of $5.2{\sim}373.8mg\%$ and were significantly higher than tertiary amines such as TMA and TMAO. DMA nitrogen in those samples was in the range of trace-31.2ppm and was high, in the dried shark(31.2ppm), alaska pollack($22.9{\sim}24.3ppm$) and octopus($17.9{\sim}18.4ppm$). In dried laver and sea mustard, however, amines were not detected at all. The levels of nitrate nitrogen in the dried marine samples ranged from zero to 16.8ppm and were high in the dried stingray(16.8ppm), alaska pollack(16.3ppm) and squid($2.2{\sim}12.4ppm$), but were less than 1.0 ppm in other samples. The levels of nitrite nitrogen were lower than those of nitrate nitrogen and it was not detected in dried sea cucumber, laver and sea mustard. Twenty eight of 31 samples contained NDMA($range=1.2{\sim}86.0ppb$), which was the only volatile N-nitroso compound found. The NDMA levels of dried stingray($2.8{\sim}86.0ppb$), alaska pollack($8.2{\sim}55.5ppb$), squid($3.3{\sim}53.2ppb$), yellow corvenia($45.9ppb$) and plain dried shrimp($15.4{\sim}17.9ppb$) were high. However, it was not detected in dried sea cucumber, laver and sea mustard. Samples, containing high levels of NDMA, also contained high nitrate and nitrite nitrogen. From above results, it can be concluded that nitrate and nitrite were major factors for the formation of NDMA in dried marine food products.

• The Korean Journal of Food And Nutrition
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• v.14 no.3
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• pp.204-210
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• 2001

전통수산 발효식품인 젓갈은 부패를 억제하기 위하여 20∼25%의 식염을 첨가하므로 짠맛이 강하고 성인병 유발과 유관하다는 단점이 있으므로 저식염 젓갈이 개발되고 있으나 저염 젓갈류는 비린내와 부패취가 강하여 기호도가 떨어질 뿐만 아니라 발암성 N-nitosamine(NA)의 생성 가능성이 높아지게 된다. 본 연구에서는 저염 젓갈의 저장성, 기호성 유지 및 NA생성을 억제코져 두류(대두, 검정콩) 및 허브류(애플민트, 페파민트, 레몬밤 및 스파아민트)의 에탄올 추출물을 각각 첨가한 저염 멸치젓을 제조하여 110일간 숙성시키면서 품질과 관련된 여러 인자 및 NA 생성여부를 실험하였다. 저염 멸치젓 숙성 중 PH, 염도 및 산도는 모든 실험군에서 숙성 110일까지 큰 변화를 보이지 않았다. 휘발성 염기질소는 저장기간에 따라 점차 증가하는 경향을 보였는데 애플민트 추출물 첨가군이 가장 큰 폭으로 증가하였다. DMA 및 TMA 질소도 증가하는 경향을 보였는데 숙성 75일째부터 그 증가폭이 두드러졌다. 질산염 질소는 젓갈 숙성 중 점차 증가하는 경향을 보였으며, 아질산염 질소는 약간 증가하는 경향이었다 NA는 N-nitrosodi-methylamine(NDMA)만이 검출되었으며 대조군에 비하여 전 실험군에 더 낮은 함량이었으며 이때 평균회수율은 63.9∼99.7%였다. 허브 추출물 첨가군에서 대조군에 비하여 월등히 낮은 함량은 NDMA가 검출되었는데, 특히 페파민트 추출물 첨가군에서는 숙성 75일까지 흔적량에 불과하였다.

• Analytical Science and Technology
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• v.26 no.6
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• pp.364-374
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• 2013

The major ten odorous compounds have been analyzed from four swine facilities in Jeju Island, in order to investigate the emission characteristics and odor contribution by different ventilation systems and manure treating types. From the study, the concentrations of $NH_3$ and TMA were high at the enclosed ventilation and scraper type facilities in winter season, and the sulfur compounds ($H_2S$, $CH_3SH$, DMS, DMDS) as well as volatile fatty acids (PA, n-BA, n-VA, iso-VA) showed high concentrations at the enclosed ventilation type facilities during winter season. The concentrations of nitrogen and sulfur compounds were high at slurry manure treat facilities. However, the volatile fatty acids (VFA) were relatively high in the scraper type swine facilities. The odor quotients of n-BA were high at four swine facilities, therefore the volatile fatty might be considered as the major odor causing compounds. Moreover the sum of odor quotient (SOQ) was high at the enclosed ventilation and scraper type facilities, and the odor contributions by volatile fatty acids were high in all swine facilities.

• Journal of Food Hygiene and Safety
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• v.12 no.2
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• pp.125-131
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• 1997

Gulbi, salted and dried yellow corvenia, is a favorite diet food in Korea from the ancient times. A Few studies have dealt with sanitary concerns related to its products, while a number of investigators studied its taste compounds. This study attemps to establish the basic data for ensuring the safety of Gulbi. The contents of nitrate and nitrite were detected 1.2 and <0.1 mg/kg in raw sample, but their contents were detected 3.6~3.9 and 1.2~2.0 mg/kg during its processing and storage of Gulbi, respectively. TMAO contents decreased while betaine, TMA, DMA and formaldehyde increased in yellow corvenia during its processing and storage. Recovery from raw, salted, salt-dried and stored sample spiked with 10$\mu\textrm{g}$/kg for NDBA was 83.2~102.7% average 92.7%). N-nitrosamine such as NDMA, NDEA and NDPA was not detected in raw sample and drastically increased during Gulbi processing and storage. The levels of NDMA, NDEA and NDPA in Gulbi stored for 30 days were about 2.7,4.5 and 5.3 times higher than those in salted sample, respectively. Regardless of cooking methods, NDMA, NDEA and NDPA during cooking when sample were cooked using direct heating methods such as a gas and a briquet fire than when sample were cooked using indirect methods such as an microwave oven and a fried pan. Indirect cooking methods was effective to minimize the N-nitrosamine formation such as NDMA, NDEA and NDPA during cooking of Gulbi.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.13-14
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• 2008

$Al_2O_3$ thin films were deposited on GaN (0001) by remote plasma atomic layer deposition (RPALD) technique using trimethylaluminum (TMA) precursor and oxygen radicals in the temperature range of 25 ~ $500^{\circ}C$. Growth rate per cycle was varied with substrate temperature from 1.8 $\breve{A}$/ cycle at $25^{\circ}C$ to 0.8 $\breve{A}$/cycle at $500^{\circ}C$. The chemical structure of the $Al_2O_3$ thin films was studied using X-ray photo electron spectroscopy (XPS). Excellent electrical properties of $Al_2O_3$/GaN MIS capacitor were grown at $300^{\circ}C$ process temperature.

• Journal of Magnetics
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• v.3 no.4
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• pp.99-104
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• 1998

The $ Sm_2Fe_{17}N_x $materials were prepared by the combination consisting of the HDDR (hydrogenation, disproportionation, desorption, and recombination) process and nitrogenation or by the conventional way consisting of nitrogenation only, and the magnetic and thermomagnetic properties of the materials were investigated. The magnetic characterisation of the prepared $ Sm_2Fe_{17}N_x $ materials was performed using a VSM. Thermal stability of the materials was evaluated using a DTA under Ar gas atmosphere. The thermomagnetic characteristics of the materials were examined using a Sucksmith-type balance. The previously HDDR-treated Sm2Fe17parent alloy was found to be nitrogenated more easily compared to the ordinary $ Sm_2Fe_{17}N_x $alloy. The $ Sm_2Fe_{17}N_x $ material produced by the combination method showed a high coercivity (12.9 kOe) even in the state of coarse particle size (around 60 ${\mu}{\textrm}{m}$). It was also revealed that the $ Sm_2Fe_{17}N_x $ material produced by the material produced by the combination showed an unusual TMA tracing featured with a low and constant magnetisation at lower temperature range and a peak just before the Curie temperature. This thermomagnetic characteristic was interpreted in terms of the competition between two counteracting effects; the decrease in magnetisation due to the thermal agitation at an elevated temperature and the increase in magnetisation resulting from the rotation of magnetisation of the fine grains comparable to a critical single domain size due to the decreased magnetocrystalline anisotropy at an elevated temperature.

• Journal of applied mathematics & informatics
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• v.27 no.1_2
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• pp.13-23
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• 2009

Some strong convergence theorems of explicit iteration scheme for asymptotically nonexpansive semi-groups in Banach spaces are established. The results presented in this paper extend and improve some recent results in [T. Suzuki. On strong convergence to common fixed points of nonexpansive semigroups in Hilbert spaces, Proc. Amer. Math. Soc. 131(2002)2133-2136; H. K. Xu. A strong convergence theorem for contraction semigroups in Banach spaces, Bull. Aust. Math. Soc. 72(2005)371-379; N. Shioji and W. Takahashi. Strong convergence theorems for continuous semigroups in Banach spaces, Math. Japonica. 1(1999)57-66; T. Shimizu and W. Takahashi. Strong convergence to common fixed points of families of nonexpansive mappings, J. Math. Anal. Appl. 211(1997)71-83; N. Shioji and W. Takahashi. Strong convergence theorems for asymptotically nonexpansive mappings in Hilbert spaces, Nonlinear Anal. TMA, 34(1998)87-99; H. K. Xu. Approximations to fixed points of contraction semigroups in Hilbert space, Numer. Funct. Anal. Optim. 19(1998), 157-163.]

• Journal of Nutrition and Health
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• v.17 no.3
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• pp.169-177
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• 1984

The changes in nuclecotides and their related compounds during the fermentation of Clam, Tapes japonica, were analyzed by high speed liquid chromatography. In raw Clam, dominant ADP was $7.86\;{\mu}mole/g$ on moisture and salt free base and the content of ATP was $3.85\;{\mu}mole/g$, AMP $3.71\;{\mu}mole/g$, hypoxanthine $0.28\;{\mu}mole/g$, inosine $0.15\;{\mu}mole/g$, respectively. But IMP was not detected in Clam ADP, ATP and AMP decreased while inosine and hypoxanthine incraesed by twenty two times and thirty there times respectively, after 63 days fermentation, when compared with raw samples. TMA- N increased while TMAO - N decreased during the fermentation The amount of TMAO nitrogen in 63 days fermented Clam was 66.0mg% on moisture and salt free base. It was belived that inosine, hypoxanthine and TMAO play an important role as flavour compounds in fermented Clam.

• KIEE International Transactions on Electrophysics and Applications
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• v.3C no.2
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• pp.66-69
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• 2003

Various semiconductor nanowires such as GaN, GaP, InP, Si$_3$N$_4$, SiO$_2$/Si, and SiC were coated conformally with aluminum oxide (Al$_2$O$_3$) layers by atomic layer deposition (ALD) using trimethylaluminum (TMA) and distilled water ($H_2O$) at a temperature of 20$0^{\circ}C$. Transmission electron microscopy (TEM) revealed that A1203 cylindrical shells conformally coat the semiconductor nanowires. This study suggests that the ALD of $Al_2$O$_3$ on nanowires is a promising method for preparing cylindrical dielectric shells for coaxially gated nanowire field-effect transistors.

• Journal of Magnetics
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• v.4 no.2
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• pp.55-59
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• 1999

In an attempt to find an effective production way of the$ Sm_2Fe_{17}N_{x-}type material, the Sm_2Fe_{17-}$type alloy with chemical composition of Sm 22.7 wt.%, Fe72.3 wt.% Nb 5.0wt.% was subjected to a HD (hydrogen decrepitation) treatment prior to a nitrogenation, and its effect on the formation of the nitride material was investigated. The nitrogenation behaviours of the alloy were investigated using a TPA(thermopiezic analysis), TMA, and DTA under nitrogen gas, and XRD. It has been found that the previous HD treatment significantly facilitated the formation of $Sm_2Fe_{17}N_{x-}$type nitride, and this was accounted for by the clean surface and the finer particle size of the powder caused by the HD treatment. It has also been found that the hydrogen atoms existing in the initial HD-treated alloy were removed almost completely during the nitrogenation. The heat output associated with the nitrogenation of the previously HD-treated alloy was found to be significantly smaller than that of the as-cast alloy.