• Membrane Journal
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• v.22 no.4
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• pp.251-257
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• 2012

For the separation and recovery of n-pentane from nitrogen environment, the poly (dimethyl siloxane) (PDMS) composite membranes supported by polyetherimide (PEI) hollow fiber membranes were prepared. To characterize the gas separation properties of the resulting membranes, the permeance of n-pentane and nitrogen, concentrations of permeate and retentate, and recovery ratio were measured for n-pentane and nitrogen mixtures. The permeance of n-pentane and nitrogen, 2485.3 and 9.9 GPU, were observed respectively. As the stage cut decreases and the feed concentration increases, the n-pentane concentration in permeate tends to increase. In the meanwhile, the recovery efficiency tends to increase as the stage cut increases and the feed concentration decreases.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.13 no.3
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• pp.109-113
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• 1980

Organic bases in the dorsal meat of wild common carp, Cyprinus carpio, were analyzed as a part of the studies on the taste compounds of fresh-water fishes. The male and female meat showed no significant differences in contents of total creatinine, betaine, TMA and TMAO. The most abundant basic compound was total creatinine $(ca.\;400mg\%)$. The amount of betaine was poor $(ca.\;66.5mg\%)$ and TMA and TMAO were trace in content $(below\;1mg\%)$.

• Korean Journal of Soil Science and Fertilizer
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• v.33 no.5
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• pp.369-375
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• 2000

To find a quick test procedure for soil nitrate concentration, two methods, i.e. "Nitracheck 404" reflectometer (Eijkelkamp, Netherlands) with nitrate test strip and a portable colorimeter "Hanna Ion Specific meter(USA) with a color development reagent, were tested for twenty soils with different nitrate contents ranged between from $10mg\;kg^{-1}$ to $340mg\;kg^{-1}$. The standard deviation, coefficient of variability, and recovery from these quick test procedures were compared with those measured by conventional Kjeldahl distillation method and nitrate ion electrode method. The nitrate concentration measured by portable colorimeter method was higher in soils with low concentration and lower in soils with high concentration than those measured by conventional methods. However, concentrations measured by test strip reflectometer method was showed the similar coefficient of variability and recovery as those by conventional methods for all soil samples. From the experimental results in this study, the test strip reflectometer method was thought to be recommendable one revealed the satisfied results for accuracy, quickness, and simplicity for field test of soil nitrate concentration.

• Korean Journal of Agricultural and Forest Meteorology
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• v.23 no.2
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• pp.89-99
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• 2021

This study was carried out to understand how factors of decomposition such as quality of the substrate (tree species), forest types, and soil·meteorological conditions affect decomposition rates and dynamics of carbon (C) and nitrogen (N) of branches in adjacent Pinus densiflora and Quercus variabilis stands in Sancheong and J inju in Southern Korea. The branch bags (30 cm × 30 cm) with branch samples (a diameter of 2.0 - 4.0 cm and length of 10 cm) were placed on the forest floor at each stand in May 2018. The branch bags were collected in August and November 2018, February and May 2019, respectively. The decomposition rates of branches in P. densiflora stands were 4.49 % for Sancheong, and 5.75 % for Jinju. Whereas, the decomposition rates in Q. variabilis were 20.01 % for Sancheong, and 24.68 % for Jinju, respectively. The decomposition of branches was more rapid in Q. variabilis compared with P. densiflora in both regions. C and N in decomposed branches were more mineralized in Q. variabilis, whereas C and N were more accumulated in P. densiflora. These results indicated that the decomposition rates, C and N of decomposed branches may be affected by differences in substrate quality such as initial N concentration and C/N ratio rather than differences between both regions including different environmental factors.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.27 no.1
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• pp.66-71
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• 1982

Field experiments of nitrogen application (0, 100, 200, 400, 800kg N/ha year) were carried out to study the nitrogen response of Sudangrass at College Farm, Seoul National Univ., in 1979 and 1980. Dry matter yield and leaf area index increased up to 400kg N/ha in 1979 and 800kg N/ha in 1980. The forage yield of 1980 was less than that of 1979, due to the extraordinarily low temperature and the decreased solar radiation during summer. Total nitrogen contents in forage increased with nitrogen application, but maximum contents were found either 400 or 800kg N levels depend on each cutting stages. Nitrate nitrogen content in forage exceded over 2000 ppm at 800kg N application. Overall percentages of N recovery were below 50% with average 34%. Net assimilation rate and nitrogen use efficiency of Sudangrass were improved in higher temperature and more sunlight condition during regrowth period.

• Journal of The Korean Society of Grassland and Forage Science
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• v.16 no.4
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• pp.253-259
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• 1996

Ammonia microdiffusion method and colorimetric measurement are described for the nitrogen determination. The diffusion of ammonia could be successfully induced by using a microdiffusion cell. It is a simple and rapid technique, which is suitable for transforming the nitrogen in digests into $NH_4CI$ for the colorimetric N determination with ammonia color reagent. Above 99% of N recovery were obtained with microdiffusion up to 15 hours. The coloration method of collected $NH_4CI$ for the colorimetric N determination was also estabilshed with a scanning in U.V. spectrophotometer. Under the proposed coloration method (0.5 mL of sample digest, 4.0 mL of $H_2O$ and 0.5 mL of ammonia color reagent), a maximal absorbance was observed at 410 nm. The kinetic measurement of absorbance showed a high stability from 5 to 45 minutes after color development. Absorbance was directly proportional to the amount of $NH_4^+-N$ present. The microdiffusion-ammonia coloration method was successfully applied to the nitrogen determination in the forms of protein-N or total -N in plant tissue. Comparing with Kjeldahl distillation method, the values obtained with described method were slightly higher and more reliable.

• Korean Journal of Soil Science and Fertilizer
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• v.36 no.6
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• pp.376-383
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• 2003

To utilize composts more efficiently, combining composts with fertilizer to meet crop requirements is an appealing alternative. A pot experiment was conducted to study the effect of application rate of composted pig manure blended with fertilizer on the availability and loss of fertilizer-N. Chinese cabbage (Brassica campestris L. cv. Samjin) plants were cultivated for 30 and 60 days. 15N-Labeled urea ($5.24\;^{15}N\;atom\;%$) was added to soil at $450mg\;N\;kg^{-1}$, and unlabeled compost ($0.37\;^{15}N\;atom\;%$) was added at 0, 200, 400, and $600mg\;N\;kg^{-1}$. The amount of plant-N derived from urea was not affected by compost application at rate of $200mg\;N\;kg^{-1}$. However, compost application at 400 and $600mg\;N\;kg^{-1}$ significantly (P<0.05) increased plant assimilation of N from urea irrespective of sampling time, probably because of physicochemical changes in the soil properties allowing urea-N to be assimilated more efficiently. The amount of immobilized urea-N increased with increasing rate of compost application at both growth periods, as the results of increased microbial activities using organic C in the compost. Total recovery of urea-N (as percentage of added N) by Chinese cabbage and soil also increased with increasing rate of compost from 71.5 to 95.6% and from 67.0 to 88.2% at the 30- and 60-days of growth, respectively. These results suggest that increasing rate of compost blending increases plant uptake of fertilizer-N and enhances immobilization of fertilizer-N, which leads to decrease in loss of fertilizer-N. However, information about the fate of immobilized N during future crop cultivation is necessary to verify long-term effect of compost blending.

• Membrane Journal
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• v.6 no.3
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• pp.173-181
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• 1996

Common volatile organic compounds(VOCs) such as toluene and methanol were removed successfully from N$_{2}$ using a novel silicone-coated hollow fiber membrane module. This novel membrane is a thin film composite(TFC) and was highly efficient in removing VOCs selectively from a N$_{2}$ stream. This membrane had some innate advantages over other silicone-based membrane in that the selective barrier was ultrathin(~1 $\mu$m) and the porosity of the polypropylene substrate was high which leads to a low permeation resistance. The substram was very strongly bonded to the coating layer by plasma polymerization and can withstand a very high pressure. A small hollow fiber module having a length of 25cm and 50 fibers could remove 96~99% of toluene as well as methanol vapors when the feed flow rate was up to 60cc/min. The percent removal of VOCs were even higher when the feed inlet concentration was higher. This process is especially suitable for treating streams having a low flow rate and high VOCs concentration. The permeances of VOCs through this membrane was in the range of $4~30 \times 10^{-9}gmol/sec \cdot cm^{2}\cdot cmHg$ for both toluene and methanol, and nitrogen permeance was between $3~9 \times 10^{-10}gmol/sec \cdot cm^{2} \cdot cmHg$. High separation factor between 10~55 for toluene/N$_{2}$ and 15~125 for methanol/N$_{2}$ were obtained depending on the feed flow rate ranges and feed VOCs concentration levels.

• Korean Journal of Soil Science and Fertilizer
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• v.35 no.5
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• pp.253-263
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• 2002

To test for the effect of applied fertilizer and nutrients on uptake and transport for paddy rice, two paddy field trials were conducted with Dongjinbyeo in degenerated salt paddy field of Jeonbuk series from 1999 to 2000. After experiment, soil acidity, content of organic matter phosphate, silicate, potassium, calcium, and total nitrogen was increased by application of fresh cattle manure(FCM). Content of Nitrogen in soil layer leached inorganic nitrogen $NO_3$ was higher that that of $NH_4$ and was high in treatment of FCM. Content of $PO_4$ was higher in FCM than other treatments. But content of potassium was in high control. During the growth of rice plant, the amount of water consumption was 477mm. The amount of supplied nitrogen was high in treatment of no nitrogen(NN), 20% reduced application of LCU(LCU-20%), and no fertilizer. In case of phosphate, the supplied amount was more than the consumed amount with the exception of treatment "no phosphate(NP) and no fertilizer(NF)". In case of potassium, the consumed amount was more than the supplied amount in all treatments. The amount of applied nitrogen in the nutrient infiltrated water was high in treatment soil test(ST), C+FCM+Si(Silicate) and the ratio of recovered nitrogen was high in 20% reduced application of LCU. The amount of applied phosphate in the nutrient infiltrated water was high in FCM and that of applied potassium was high in 20% reduced application of LCU. Nitrogen use efficiency of paddy rice was high in 20% reduced application of LCU and use efficiency of phosphate and potassium was high in C+Si(Silicate). Grain yield of rice was high in order of 20% reduced application of LCU>C+Si=C+FCM+Si>C+FCM.

• 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.