• 한국식품위생안전성학회지
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• 제19권3호
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• pp.126-131
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• 2004

유자추출물 및 유자주스와 유자주스의 유기산, ascorbate 및 phenolic 획분을 이용하여 nitrosamine(NA) 생성의 주요 전구물질인 아질산염의 소거능과 N-nitrosodimethylamine(NDMA)의 생성에 미치는 영향을 분석하였다. pH 1.2와 4.2의 반응계에서 아질산염 소거능과 NDMA 생성억제능은 시료 첨가량이 증가함에 따라 반응계의 pH가 산성영역 일수록 더 높은 활성을 보였다. 유자 과육 및 과피추출물을 첨가한 경우 알질산염 소거능 및 NDMA 생성억제능은 과피추출물에서 다소 높은 활성을 보였다. 유자주스와 각 획분의 아질산염 소거느은 pH 1.2에서 주스를 첨가한 경우에 92.2${\pm}$3.2~98.2${\pm}$3.4%로 가장 높았으며, 다음으로 유기산 획분, phenolic 획분 및 ascorbate 획분의 순으로 나타났다. 유자로부터 NDMA 생성억제에 주된 영향을 주는 물질은 유기산인 것으로 생각된다.

• 한국수산과학회지
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• 제27권3호
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• pp.247-258
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• 1994

우리나라 수산 건제품중 발암성 N-Nitrosamine(NA)의 생성요인을 구명하기 위하여 시판 되고있는 소건품 10종(17개 시료), 조미건제품 1종(3개 시료), 자건품 3종(5개 시료), 염건품 1종(1개 시료), 동건품 1종(3개 시료) 및 해조류 2종(2개 시료)에 대하여 NA의 전구물질인 아민류, 질산염 및 아질산염을 분석하였고, GC(Gas Chromatography)-TEA(Thermal Energy Analyzer)를 이용하여 NA를 분석 정량하였으며, 또 GC-MS(Mass Spectrometry)로 N-Nitrosodimethylamine (NDMA)을 동정하였다. 수산 건제품의 아민류는 대체로 betaine질소가 다른 아민류에 비해 월등히 높아 건조 문어에서 $357.4{\sim}373.8mg\%$로 가장 많았고, 다음으로 건조새우 및 건조 오징어순이었다. 그러나 건조 해조류에서는 전혀 검출되지 않았다. TMAO질소는 $2.2{\sim}20.7mg\%$ 범위였으나, 건조해삼에서는 흔적량이었고, 건조 해조류에서는 전혀 검출되지 않았다. TMA질소는 TMAO질소에 비해 대체로 높게 정량되어 건조 상어에서 $57.2mg\%$, 건조 옥돔 $40.1mg\%$ 였으며, 그외 건조 해조류와 건조해삼을 제외한 모든 시료에서 $10.0mg\%$ 이상이었다. 분석된 시료중 dimethylamine(DMA) 역시 건조 해조류와 건조 해삼을 제외한 모든 시료에서 검출되었는데 비교적 함량이 높은 시료는 건조 상어(31.2 ppm), 동건 명태($22.9{\sim}24.3\;ppm$) 및 건조문어 ($17.9{\sim}18.4\;ppm$)등이었다. 질산염 질소는 불검출에서 최고 16.8 ppm범위였는데 건조 가오리(16.8ppm), 동건 명태(16.3ppm) 및 건조 오징어($2.2{\sim}12.4ppm$) 등에서 높은 함량을 보였으나, 그외 시료에서는 1.0 ppm미만이었다. 아질산염 질소는 질산염 질소에 비해 다소 낮은 경향을 보여 건조 해조류 및 건조 해삼에서는 전혀 검출되지 않았으나, 반면에 건조 가오리에서는 최고 9.6 ppm으로 정량되었다. NDMA의 농도는 시료간에 큰 함량차를 보여 건조 해조류 및 건조 해삼에서는 전혀 검출되지 않았으나, 건조 가오리($2.8{\sim}86.0ppb$), 동건 명태($8.2{\sim}55.5ppb$), 건조 오징어($3.3{\sim}53.2ppb$), 굴비(45.9ppb) 및 소건 새우($15.4{\sim}17.9ppb$) 등에서는 높은 함량을 보였으며 그외 시료에서는 10ppb미만 이였다. 대체로 NDMA가 높게 검출된 시료에서는 질산염과 아질산염질소의 함량이 높아 이들이 NBMA의 생성에 주된 요인이라는 것을 알 수 있었고, 동일 어종간에도 시료에 따라 함량차가 심한 것도 역시 질산염과 아질산염의 오염 정도에 의한 것으로 판단된다.

• 대한환경공학회지
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• 제28권4호
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• pp.355-361
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• 2006

고정상 생물여과지(biofiiter)에서 유입 C/N(COD/Nitrate)비와 용존산소(DO) 농도가 지하수로부터 질산성 질소를 제거하는데 미치는 영향을 관찰하였다. 유입 C/N비 10과 4.0에서 30 mg/L로 유입된 질산성 질소는 생물학적 탈질반응에 의해 완전히 제거되었다. 반면, 유입 C/N비 2.0에서는 전자공여체가 부족하였기 때문에 5.0 mg/L의 질산성 질소가 유출되었다. 게다가, 유입 C/N비가 2로 감소함에 따라 5.0 mg/L에 달하는 아질산성 질소가 발생하였다. 유입 C/N비 5에서 DO 농도의 증가는 탈질반응을 저해하였으며, 질산성 질소제거효율을 감소시켰다. 아황산나트륨($Na_2SO_3$)을 이용하여 유입 DO농도를 조절할 경우, 0.3 mg/L의 낮은 DO에도 불구하고 유출수 중 3.6 mg/L의 아질산성 질소가 잔류하였다. 반면, 질소가스를 이용하여 DO농도를 0.3 mg/L로 조절한 경우, 유입된 질산성 질소는 완전히 제거되었으며, 아질산성 질소는 검출되지 않았다. 생물여과지에서 유입된 질산성 질소를 제거하는데 소비된 유기물은 $3.0{\sim}3.5gSCOD/g{NO_3}^--N$의 범위이었으나, DO 농도가 5.5 mg/L로 증가함에 따라 소비된 그 양은 증가하였다. 높은 DO 농도 및 낮은 유입 C/N비와 함께 아황산나트륨을 이용한 DO 농도 조절은 생물학적 탈질반응에 영향을 주었으며, 질산성 질소제거효율을 감소시키고 아질산성 질소가 축적되었다.

• Preventive Nutrition and Food Science
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• 제8권4호
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• pp.321-329
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• 2003

In order to provide data on N-nitrosamine (NA) and sanitation in fish available in domestic markets, this study analyzed the levels of NA and its precursors in 9 samples of sea breams and yellow croakers, 12 samples of red-flesh fish, 38 samples of white fish, 5 samples of Alaska pollacks and cod, and 8 species of imported fish. Sea breams and yellow croakers had nitrite concentrations ranging from non-detectable (ND) to 7.4 mg/kg, red fish ND to 5.3 mg/kg, white fish ND to 18.7 mg/kg, Alaska pollacks 0.3 to 2.2 mg/kg, and imported fish from 0.4 to 12.8 mg/kg. Nitrates in sea breams and yellow croakers ranged from 1.2 to 41.19 mg/kg, red fish 0.6 to 26.1 mg/kg, white fish 4.3 to 75.9 mg/kg, Alaska pollacks 0.4 to 3.1 mg/kg, and imported fish ND to 16.0 mg/kg. DMA concentrations were 69.8 to 219.9 mg/l00 g in sea breams and yellow croakers, 4.1 to 336.3 mg/l00 g in red fish, 1.3 to 331.9 mg/l00 g in white fish, 15.7 to 312.3 mg/l00 g in Alaska pollacks, and 1.0 to 71.8 mg/l00 g in imported fish. TMA concentrations in sea breams and yellow croakers, red fish, white fish, Alaska pollacks and imported fish were 43.8∼496.2, 12.3∼127.0, 2.0∼525.9, 15.4∼122.4, and 4∼70.6 mg/l00 g, respectively. For NA in fish distributed in local markets, only N-nitro-sodimethylamine (NDMA) was detected, and its concentrations ranged from 4.7 to 73.7 $\mu\textrm{g}$/kg in sea breams and yellow croakers, 2.2 to 56.5 $\mu\textrm{g}$/kg in red fish, ND to 143 $\mu\textrm{g}$/kg in white fish, 3.8 to 33.3 $\mu\textrm{g}$/kg in Alaska pollacks, and 2.1 to 102.2 $\mu\textrm{g}$/kg in imported fish.

• 한국환경과학회지
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• 제14권5호
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• pp.513-520
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• 2005

For the destruction of toxic chlorinated organic compounds, this study proposes improved supercritical water oxidation method (multistep oxidation) using sodium nitrate as an oxidizer. This method solves the problems involved in the existing supercritical water oxidation method. Multistep oxidation means that $NaNO_3$ is oxidized to $N_2\;via\;NaNO_2$ and NO. Toxic and hard to destroy organic substances like para-dichlorobenzen(4-DCBz), polychlorinate biphenyl(PCB) ware oxidized to non toxic substances in a condition, in which rapid pressure and temperature rise is restrained as much as possible. 4-dichlorobenzene(4-DCBz) and Polychlorinate biphenyl(PCB) in condition$(450^{\circ}C,\;p_w=0.25g/cm^3,\;30min)$ Was discomposed perfectly.

• ALGAE
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• 제22권3호
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• pp.235-240
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• 2007

The red tide-causing flagellate Chattonella anticfua can cause mass fish kills by their clogging in fish gills. Thisstudy examined the nutrient requirements of C. antiqua isolated from Korea. C. anticfua displayed maximum growthat the day five, followed by a decrease in cell density. Nitrate and nitrite were the preferred nitrogen sources, alonewith adenosine diphosphate for phosphorus compounds. In medium that contained ammonium, a significantdecrease in cell density was observed. Half-saturation constants, Ks, calculated from the maximum growth ratewere 4.94 U|M for NC>3 and 0.79 flM for P04. The growth of C. antiqua was not within the function of the N:P ratio (RU= 0.29). With an N:P ratio as low as 10, the increase in cell density was apparent, with a higher division rate. At lev-els above 50 fiM of NaNOg or 8 ;uM of NaHUPCU, the growth rates were somewhat decreased. Phosphate was thelimiting factor for C. antiqua growth since the starvation of phosphate had brought about a rapid decrease in celldensity in semi-continuous culture. Studies about the temporal modification of the efficiency of nitrate or phosphateuptake may be necessary to explain the bloom dynamics of C. antiaua.

• Membrane and Water Treatment
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• 제9권3호
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• pp.189-194
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• 2018

Electrochemical reduction of nitrate was studied using Zn, Cu and (Ir+Ru)-Ti cathodes and Pt/Ti anode in a cell divided by an ion exchange membrane. During electrolysis, effects of the different cathode types on operating parameters (i.e., voltage, temperature and pH), nitrate removal efficiency and by-products (i.e., nitrite and ammonia) formation were investigated. Ammonia oxidation rate in the presence of NaCl was also determined using the different ratios of hypochlorous acid to ammonia. The operating parameter values were similar for all types of cathode materials and were maintained relatively constant. Nitrate was well reduced and converted mostly to ammonia using Zn and Cu cathodes. Ammonia, produced as a by-product of nitrate reduction, was oxidized in the presence of NaCl in the electrochemical process and the oxidation performance was enhanced upon increasing the hypochlorous acid-to-ammonia ratio to 1.09:1. Zn and Cu cathodes promoted the nitrate reduction to ammonia and the produced ammonia was finally removed from solution by reacting with hypochlorite ions. Using Zn or Cu cathodes, instead of noble metal cathodes, in the electrochemical process can be an alternative technology for nitrate-containing wastewater treatment.

• 한국식품영양과학회지
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• 제20권6호
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• pp.565-571
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• 1991

A short time microwave heat treatment, bringing in hot NaCl solution, addition of KCI, CaCl2, MgCl2 into brining solution and salts mixture of phosphates into half fermented dongchim were investigated for their effects on some quality of dongchimi, a Korean pickle of Chinese radish roots, during fermentation. The reference dongchimi was prepared by brining the radish roots in 7% NaCl added with seasonings at $25^{\circ}C$. The result showed that microwave heat treatment affected little on the pH or total acidity change during fermentation. Soaking the roots in 80-9$0^{\circ}C$ hot salt solution significantly reduced the fermentation and softening rate of dongchimi while a rather rapid fementation was found for those soaked in 7$0^{\circ}C$. Addition of KCI and CaCl2 into brining solution slowed the pH decrease and softening of the roots, respectively. The dangchimi added with the salts mixture of phosphate, citrate and nitrite was significantly extreneded the fermentation time to pH 4.0 by more than two folds.

• 한국안전학회지
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• 제14권1호
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• pp.86-92
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• 1999

This study was carried out to investigate the effect of chemical cleaning of corrosion product on cooling system made of copper as a basic material and using cooling water as pure water. We studied chemical cleaning condition that minimizes the influence on basic material by means of EDTA solution so as to eliminate the slurry in cooling system. In addition, the proper amount of NALCO-39L (Nitrite-Borate-BZT mixture) as a inhibitor was determined in order to protect the copper in cooling system against corrosion after chemical cleaning and the effect of corrosion resistance on the copper surface treated was excelent in comparison with surface untreated. As a result, we found that the main components of sludge in cooling system produced by corrosion of copper were $Cu_2O$, CuO, Cu, and Fe. The optimum condition of chemical cleaning was 400ppm EDTA solution at $60^{\circ}C$. Inhibitor concentration needed to treat the surface of pure copper was 15～20ppm per unit area and corrosion rate of copper treated with 500ppm inhibitor solution for 72 hrs at $60^{\circ}C$ was remarkably decreased as compared with that of pure copper.

• 센서학회지
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• 제32권2호
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• pp.67-74
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• 2023

A microfluidic paper-based analytical device (µPAD) is proposed for the selective detection of ammonia in water by using the modified Berthelot reagent and a fluidic channel consisting of hollow paper. The modified Berthelot reagents were uniformly dispersed in cyclohexane and then immobilized in a detection zone of the µPAD. The loading position of the reagents and the type of a sample flow channel were optimized to achieve a sensitive ammonia detection within a short analytical time. The NH₃ µPAD exhibits a linear colorimetric response to the concentration of ammonia dissolved in water in the range of 1-100 mg L^-1, and its limit-of-detection is 1.75 mg L^-1. In addition, the colorimetric response was not influenced by the addition of 100 mg L^-1 nitrogen containing compounds (sodium nitrate, sodium nitrite, uric acid, hydroxylamine, butylamine, diethylamine) or inorganic salts (NaCl, Na₂HPO₄), presenting the enough selectivity in the detection of water-dissolved ammonia against possible interferents.