• Journal of Animal Science and Technology
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• v.51 no.4
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• pp.337-342
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• 2009

The feasibility of reutilization of magnesium ammonium phosphate (MAP) or struvite slurry recovered from the process through microwave irradiation was studied in this experiment. For this purpose, 4 different operations were performed with or without Mg source addition and different levels of MAP recycled in a batch reactor. Dissolution rate of MAP, ${NH_4}^+$ elimination pattern and physicochemical changes of MAP during microwave irradiation were also studied. The result showed that only 33% orthophosphate ($PO_4-P$) and 27% $NH_4-N$ removal occurred without adding any external Mg source (run A), whereas 87% $PO_4-P$ and 40% $NH_4-N$ removed when 1.0 M ratio of $MgCl_2$ (run B) was added based on $PO_4-P$ in influent. Although the addition of 1.0 molar ratio of microwave irradiated MAP (Run C) removed lower $PO_4-P$ and $NH_4-N$ than 1.0 M $MgCl_2$ (run B), $PO_4-P$ removal was double when compared with no Mg addition (run A). Addition of half MAP and half $MgCl_2$ (run D) showed the similar removal efficiency (88% $PO_4-P$ and 35% $NH_4-N$) with sole $MgCl_2$ addition (run B). Based on these results, the reutilization of MAP irradiated by microwave would be a feasible way to enhance the removal efficiencies of N and P, as well as curtail the Mg chemical usage. Track study showed that $NH_4-N$ gradually increased at initial stage of microwave irradiation of MAP, and then started eliminating from liquor as temperature increased over $45^{\circ}C$. Dissolution rate of ${PO_4}^{-3}$ during microwave irradiation was proportional to the initial MAP concentration, having $0.0091x^{0.6373}$ mg/sec. It was found from the scanning electron microscope (SEM) study that physical structure of MAP crystal started breaking down into small cube granules within very short time by electromagnetic vibration force during microwave irradiation and then gradually melted down into solution.

• Applied Chemistry for Engineering
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• v.28 no.2
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• pp.171-176
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• 2017

The nitrogen plasma thermal decomposition and recovery processes for $CHClF_2$ (Chlorodifluoromethane) refringent were investigated. The steam generator was employed to provide superheated steam reactor, supporting the decomposition reaction of refringent. Even though over 94% of R-22 was decomposed on the condition of 60 A and 9.0 kW, a higher power and specific energy density were required to achieve the complete combustion of carbon materials. In the operating condition of 60 A and 12.6 kW, $O_2$/R-22 ratio in reactants gases are a key factor to obtain much higher decomposition ratio during process. It should be noticed that injecting the mixture of $O_2$ and air was much more effective than injecting the air consisting equivalent $O_2$ amount.

• The Korean Journal of Pesticide Science
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• v.18 no.4
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• pp.278-295
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• 2014

Fast and accurate multi-residue pesticides inspecting method needs in Agro-Fishery Products Inspection Center. So, We tried to seek the optimum method using GC-TOF/MS, GC-ECD, GC-NPD after QuEChERS sample preparation. In GC-TOF/MS, 138 kinds of pesticide were spiked at 0.3 and $0.5{\mu}g/g$for the identification and quantification in lettuce sample. Recoveries of 77 pesticides were between 70 and 130% with RSD (relative standard deviation lower than 20% at $0.3{\mu}g/g$. In GC-ECD, NPD, 146 kinds of pesticide were spiked for the identification and quantification in lettuce. Recoveries of 61 species were between 70 and 130% with lower than 20%. These results indicated that GC-TOF/MS, GC-ECD, NPD analysis with the QuEChERS sample preparation can be partly applied to multi-residue pesticides in vegetables.

• 한국신재생에너지학회:학술대회논문집
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• 2010.06a
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• pp.246.1-246.1
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• 2010

본 연구는 바이오가스의 에너지효율성을 높이기 위한 연구로서 바이오가스 정제공정과 초저온액화공정을 통하여 액화바이오메탄을 생산하는 바이오가스 고질화기술개발 연구이다. 바이오가스 정제공정은 탈황, 제습, 흡착, 압축, $CO_2/CH_4$ 분리공정으로 구성하고, 초저온액화공정은 열교환기, $CO_2$ 제거설비, 질소냉매 공급공정으로 구성하여 혐기성소화조에서 발생하는 바이오가스($CH_4$ 농도: 60~65%, $H_2S$: 1,500~2,500ppm)를 $200Nm^3/hr$의 유량으로 인입시켜 액화바이오메탄을 생산하였다. 연구결과, 탈황공정에서는 가성소다 세정법을 이용하여 1,500~2,500ppm으로 인입되는 $H_2S$를 100ppm 이하로 제거한 후, 흡착법을 이용하여 $H_2S$를 완전히 제거하였다. 바이오가스에 포화된 수분은 냉각제습과 흡착제습공정을 통해 Dew point $-70{\sim}-90^{\circ}C$까지 제거하여 안정적으로 $CO_2/CH_4$ 분리공정에 인입시켰다. $CO_2/CH_4$ 분리공정은 흡착방식을 적용하여 $CH_4$ 순도가 95% 이상인 바이오메탄을 생산하였으며, 이때 메탄 회수율은 약 87%이였다. $CO_2$가 분리된 바이오메탄은 초저온액화공정을 이용하여 액화바이오메탄으로 전환시켰다. 이때 초저온액화공정은 Reverse Brayton cycle로 구성하였으며, 냉매로는 질소를 사용하였다. 액화바이오메탄의 생산은 바이오메탄을 등엔트로피과정인 단열팽창을 통하여 $-155{\sim}-159^{\circ}C$의 초저온으로 냉각되는 질소냉매와 열교환기에서 열교환시켜 이루어졌으며 그 생산량은 $3.46m^3$/day(1bar, $-161^{\circ}C$)이었다.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.13 no.3
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• pp.115-119
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• 1980

Snakehead, Channa argus, is one of the most palatable fresh-water fishes in Korea; however, relatively little is known about the characteristics of taste. The present study was undertaken to analyze the proximate composition as well as the taste compounds of dorsal muscle of Korean snakehead. In the dorsal meat, glycine, taurine, alanine and lysine were abundant. Among these, glycine was the most dominant, occupying $63\%$ of total free amino acid. The amount of IMP was $2.78{\mu}mole/g$ and those of another nucleotides and their related compounds were not so high as compared to that of IMP. About $43\%$ of the total extractive-N was total creatinine-N. But the content of betaine-N was very low, occupying only $0.8\%$ of the total extractive-N and TMA-N and TMAO-N were trace in content. In snakehead, the sum of the nitrogen in these constituents amounted to nearly $80\%$ of total extractive nitrogen.

• Korean Journal of Food Science and Technology
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• v.31 no.1
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• pp.13-19
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• 1999

In order to investigate the composition and the actual status of extractive nitrogenous compounds in the fresh 'Gae-bul' (echiuroid), a kind of echiurida (Urechis unicinctus), the extract was analyzed separately into extractive nitrogen, free amino acids (FAAs), oligopeptides, nucleotides and related compounds, quaternary ammonium bases, and guanidino compounds, using specimens collected at fish market in April 1988. The extractive nitrogen of echiuroid was $601{\sim}610mg/100g$. Thirty-two kinds of FAAs were found, and the total of them in it was $2,437{\sim}2,609\;mg$. Glycine, alanine, taurine, and serine were the major FAAs in the echiuroid extracts. The large amount of glycine $(1,075{\sim}1,171mg)$ was noted in the extract. The sum of ATP and its related compounds was $3.04{\sim}3.12\;{\mu}mol/g$, and predominant compound was the AMP. Besides, CTP, GTP, UTP and their related compounds were also detected, and the total amount of them was $1.92{\sim}3.74\;{\mu}mol/g$. The lower homarine, trigonelline, TMAO, TMA, and creatine were detected in the extracts. The extractive nitrogenous constituents of medium size and large size echiuroid were almost the same level each other. The total nitrogens of the compounds analyzed for each samples accounted for more than 90% of the extractive nitrogen in this study.

• Korean Journal of Soil Science and Fertilizer
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• v.39 no.5
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• pp.285-291
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• 2006

The lysimeter ($1.2m\;with{\times}1.6m\;length$) experiment using $^{15}N$ tracer method was conducted to investigate the influence of slopes (degree 5, 15 and 30%) and fertilizer application methods (solid application and fertigation) on the behavior of applied urea in saprolite piled highland with Chinese cabbage cultivation. NDFFs(nitrogen derived from fertilizer) in soil were increased with decreasing of degree of slope and of depth of soil. The recovery as percentage of fertilizer nitrogen by Chinese cabbage were 69.5% for solid application and 76.5% for fertigation in 5% slope, 65.0% for solid application and 70.2% for fertigation in 15% slope, and 56.1% for solid application and 62.3% for fertigation in 30% slope. There, fertigation will make great contributions to the reduction of environmental contamination by run off and to the increase of fertilizer efficiency in Chinese cabbage cultivated highland.

• Journal of the Korean Society of Food Science and Nutrition
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• v.26 no.4
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• pp.614-619
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• 1997

To examine effects of drying methods on the formation of N-nitrosamine(NA) in squid during its drying. Three different types of dried products, which were made by sun, hot-air and traditional drying of squid after removal of intestines, were utilized. NA was analyzed by a gas chromatography-thermal energy analyzer. The contents of nitrate and nitrite nitrogen in dried products were in the range of 0 to 5.2mg/kg and 0 to 2.7mg/kg, respectively. The contents of TMAO and betain nitrogen in squid during its drying decreased, while those of TMA and DMA nitrogen increased. The contents in dried products were 27.8~29.2mg% and 10.4~12.3mg/kg, respectively. N-Nitrosodimethylamine (NDMA) was only detected in squid during its drying, recovery from raw sample and its dried pro- ducts spiked with 10$\mu\textrm{g}$/kg for NDPA was 81.0~ 100.0%. NDMA in raw samples was found to be below 0.05$\mu\textrm{g}$/kg. The levels of NDMA in squid increased remarkably during its drying and those in dried products were ranged from 2.7 to 42.7$\mu\textrm{g}$/kg. The effects of drying methods in squid were found to be quite different. the levels of NDMA in traditionally dried products were 11~16 and 3~4 times higher than those in sun dried and hot-air dried products, respectively It is believed that high levels of NDMA were detected in traditionally dried products because NDMA was formed from reaction between various amines and nitrogen oxide produced by combustion of briquet during drying of squid.

• Analytical Science and Technology
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• v.15 no.5
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• pp.466-474
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• 2002

The analytical method of 14 kinds of coplanar - PCBs was established and applied the soil sample. The three kinds of extraction solvents (toluene, acetone: n-hexane, dichloromethane) were selected to apply the soil sample. The silica gel, florisil and alumina column cleanup also performed to compare the elution recovery. The average recovery of selected solvents in soil A, B and C was surveyed the 84.25%, 56.09% and 44.69% for toluene, 52.56%, 81.42% and 58.53% for acetone : n - hexane and 55.94%, 71.33% and 61.05% for dichloromethane. The average recovery is represented 49.99% for silica gel (n - hexane 100 mL), 69.65% for florisil (6% ether/n - hexane 100 mL), and 65.23% for alumina (2% DCM : n - hexane 100 mL, 50% DCM: n-hexane 150 mL). In silica gel (n - hexane) and florisil (6% ether : n - hexane) cleanup, the 14 kinds of coplanar PCBs eluted until 40 mL. In the silica gel and florisil columns cleanup, the amounts of elution solvent can be reduced from these results, but the researcher has to confirm the elution amounts before performing the experiments. In alumina cleanup process, the result was obtained to the 100 mL of elution solvents (2% DCM: n-hexane 100 mL and 50% DCM: n-hexane 40 mL), therefore the change of elution solvent is necessary to develop the simple procedure.

• Korean Journal of Environmental Agriculture
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• v.24 no.2
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• pp.132-138
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• 2005

Objective of this research was to evaluate the fate of nitrogen and phosphorous in hydroponic waste solution from the plastic film house cultivation applied to the upland soil by column leaching and field experiment. The pH and EC of leachate were decreased by the reaction with the upland soil in the column leaching experiment. The EC and concentrations of $H^+,\;K^+,\;and\;{NH_4}^+$ of leachate were decreased as the column length (soil depth) was increased. But these were increased as the amounts of the hydroponic waste solution were increased field experiment growing red pepper (Capsicum annum L.) to monitor the nutrients movement using ion exchange resin capsule demonstrated that the nutrient concentration of soil solution was increased in the orders of $PO_4-P. Nitrate concentration of resin capsule inserted into the soil was relatively higher than other nutrients $(NH_4-N\;and\;PO_4-P)$ at the 45 cm of soil depth. The overall results demonstrated that the hydroponic waste solution could be recycled as plant nutrients to enhance fertility of soils. But nitrate leaching was a major factor for safe use of the hydroponic waste solution in soil.