• 한국환경과학회지
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• 제8권1호
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• pp.33-43
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• 1999

This paper aims to describe the characteristics of air pollution using air pollutants concentration and meteorological data observed at Kimhae from December 1996 to November, 1997. The results are as follows : The concentration distribution of sulfur dioxide($SO_2$), carbon monoxide(CO), particulate matter(PM-10), and nitrogen dioxide($NO_2$) is high during the late fall and winter and low during the summer, but ozone concentration is low during the winter season and high during summer season except Jangma period and these distributions appear to be closely connected with insolation and the number of clear day. Diurnal variation of concentrations for sulfur dioxide, particulate matter, and carbon monoxide are high during the rush hours and nighttime and low during the daytime and these variations are distinct toward the winter season. And diurnal variation of nitrogen dioxide concentration has also same pattern and these patterns are closely related to the increasing traffic volume at rush hours. Diurnal variation of ozone concentration is generally increase for daytime and decrease for the late afternoon and are closely related to the insolation and photochemical reaction. The 24 hour average concentrations of air pollutant observed at Kimhae represented a positive correlation and a negative correlation for $O_3$ and also a negative correlation for the meteorological elements such as wind speed and cloud cover.

• Asian-Australasian Journal of Animal Sciences
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• 제24권3호
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• pp.358-363
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• 2011

To investigate the effect of nitrogen fertilization on the quality of tropical grass silage, guinea grass grown with 3 types of nitrogen fertilizers, namely, urea, ammonium sulfate, and compound fertilizer 804, at 2 fertilization levels, 0.5 and 2.5 kg $Na^{-1}$ (0.5 N and 2.5 N, respectively), was subjected to silage fermentation. Silage fertilized with 0.5 N showed butyrate-dominant fermentation, irrespective of the type of fertilizer used. On the other hand, fermentation of silage fertilized with 2.5 N was significantly affected by the type of fertilizer used; fertilization with ammonium sulfate and compound fertilizer 804 resulted in silage that contained a large amount of butyrate and no lactate; this silage was considered to be of a significantly low quality as compared with silage fertilized with 0.5 N. Among silage fertilized with 2.5 N, the desirable butyrate-free fermentation was found only in urea-fertilized silage, which had the best quality. Grass material fertilized with a high level of urea accumulated a relatively high concentration of nitrate nitrogen (0.22% dry matter). Our results presented here suggest that nitrogen fertilizer management could affect the quality of tropical grass silage and that a relatively high concentration of nitrate in silage may promote butyrate-free fermentation even in tropical grass silage.

• 상하수도학회지
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• 제35권6호
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• pp.405-415
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• 2021

MMBR system has been suggested as a promising system to resolve harvesting problems induced from low settling efficiency of microalgae. And recently, a lot of research on reducing fouling at the MMBR system has investigated focused on EPS in many cases. EPS of microalgae mainly consists of polysaccharides and protein components, and is produced through photosynthesis and nitrogen-carbon metabolic pathways. Especially, P-EPS is one of major compounds which occur membrane fouling phenomenon, as its hydrophobic protein components cause floc formation and cake layer accumulation. And it is already known that almost every microalgae can metabolize P-EPS or Chl-a when nitrogen sources as a substrate is insufficient or exhausted situation. With the above backgrounds, uptake rates of P-EPS or Chl-a by Scenedesmus quadricauda according to the type of carbon source and nitrogen concentration were evaluated in order to verify correlation between carbon source vs P-EPS production, and indeed Scenedesmus quadricauda uses P-EPS or Chl-a when the amounts of nitrogen sourc es in the feed is not satisfied. As a result, it was shown that P-EPS and Chl-a production were increased proportional to nitrogen concentration under organic carbon condition. And especially, the amo unts of P-EPS and Chl-a in the cell were diminished with the nitrogen source becomes insufficient or exhausted. Because P-EPS accelerates fouling at the MMBR system, P-EPS degradation by Scenedesmus quadricauda in order to get nitrogen source may contribute to reducing fouling. About a affects of N-consumed Chl-a to the MMBR fouling, more survey is needed. On the contrary, considering the purpose of MMBR system of this study, i.e. harvesting useful high value microalgae efficiently feeding adequate industrial process wastewater, it seems like difficult to maintain satisfied metabolic activity and to harvest with high yield rate using nitrogen-poor MMBR feed.

• 한국재난정보학회 논문집
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• 제16권3호
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• pp.542-549
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• 2020

연구목적: 액비의 발효과정에서 생산된 질산성질소는 물의 오염지표로써 본 연구에서는 액비가 살포된 4개의 연구지역을 선정하고, 질산성질소의 오염 농도를 추정할 수 있는 모델을 제작하고자 하였다. 연구방법:현장촬영에 앞서 액비의 비율을 0%, 25%, 50%, 75%, 100%로 5개의 군으로 나누어 스펙트럼 라이브러리를 구축하였다. 스펙트럼의 양상을 토대로 연구지역에서 획득한 초분광 영상에 PLSR (Partial least squares regression) 방법을 적용하였다. 연구결과:구축한 액비의 스펙트럼을 1차, 2차 미분하여 질산성질소의 거동을 확인하였다. 현장실험의 영상을 이용하여 PLSR 농도 추정 모델링을 실시하여 실제 질산성질소의 농도와 비교하였다. 결론: PLSR 농도 추정 모델과 실제 질산성질소의 농도를 비교하였을 때 질산성질소의 농도가 70 mg/kg 이상인 고농도 지역에서 탐지가 가능하다고 판단되었다.

• 한국환경복원기술학회지
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• 제14권6호
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• pp.17-27
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• 2011

Prunus serrulata var. serrulata f. spontanea (E. H. Wilson) C. S. Chang was treated with dried swine excrement at various concentration levels, and their growth reactions and the contents of total kjeldahl nitrogen and total phosphoric acid were analyzed. The result is as follows; 1. When the plants were treated with 0.25% of dried swine excrement, the seed germination rate of Prunus serrulata var. serrulata f. spontanea was higher than that of the control. However, it showed a tendency to decrease when the treatment concentration got higher than 0.25%. 2. The growth rate of species was highest when they were treated with 0.25% of dried swine excrement. It tended to decrease with higher treatment concentration than 0.25%. Significant difference was clear between the control and the experimental plants of Prunus serrulata var. serrulata f. spontanea. 3. The contents of nitrogen and phosphoric acid in Prunus serrulata var. serrulata f. spontanea also got higher as the concentration of dried swine excrement increased. However, the content of total kjeldahl nitrogen was highest in the leaves, and followed by the roots and stems. In contrast, the content of total phosphoric acid were highest in the roots, and followed by the leaves and stems. Therefore, stems had the lowest contents of both nitrogen and phosphoric acid. 4. The contents of total kjeldahl nitrogen and total phosphoric acid in the soil were measured before and after the growth experiment of Prunus serrulata var. serrulata f. spontanea treated with dried swine excrement. The contents of nitrogen and phosphoric acid significantly decreased after the experiment. In conclusion, the contents of total kjeldahl nitrogen and total phosphoric acid accumulated in the plants increased as the concentration level of dried swine excrement got higher. The seed germination and plant growth rates were best at 0.25% treatment of dried swine excrement. The treatment of dried swine excrement may bring high effects on increasing the plant growth rate but could damage the plants with higher concentration than they need. Different optimal concentration levels of dried swine excrement for different plants should be found before it is used as fertilizer.

• 한국자원식물학회지
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• 제35권2호
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• pp.192-200
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• 2022

본 연구에서는 부지화 잎의 무기양분 농도 측정 결과를 바탕으로 질소를 제외한 다른 무기양분의 함량을 통해서 잎의 질소 결핍 여부를 구분하는 머신러닝 모델을 개발하였다. 그러기 위해서 부지화의 질소결핍구와 대조구의 잎 샘플을 분석한 36개의 데이터를 부트스트랩핑 방법을 통해서 학습용 데이터셋 1,000 여 개로 증량시켰다. 이를 이용해 학습한 각 모델을 테스트한 결과, gradient boosting 모델이 가장 우수한 분류성능을 보여주었다. 본 모델을 이용해 질소함량을 직접적으로 분석할 수 없는 경우, 잎의 무기성분 함량에 기반하여 질소결핍 가능성 여부를 판단해 질소가 부족한 부지화 나무를 분별하고, 정확한 질소함량을 측정하게 유도하여 그에 기초한 적정 질소비료 시비를 가능케 하고자 하였다.

• 열처리공학회지
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• 제24권6호
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• pp.318-326
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• 2011

This study has been performed to investigate the effect of Al addition on High Temperature Gas Nitriding (HTGN) in 13%Cr-0.16%C stainless steel with different Al contents of 0.54%, 1.76% and 2.36%, respectively. HTGN treatment was carried out at $1100^{\circ}C$ for 1 hr, 5 hrs and 10 hrs. Nitrogen-permeated surface layers showed round type carbides of $Cr_{23}C_6$ and needle type nitrides of AlN in the matrix of martensite, representing 600~700 Hv. And the thickness of the surface layer increased with increasing Al content and HTGN treatment time. The inner region that was not permeated nitrogen showed chromium carbides in the mixed phase of martensite and ferrite for the 0.53% Al alloyed steel, however chromium carbides in the matrix of ferrite single phase were shown for the steels with the addition of 1.76%Al and 2.36%Al, representing the hardness of ~200 Hv. During nitrogen permeation from surface to the interior, substitutional elements of Cr, Al and Si moved toward the surface and interstitial element of carbon also moved from interior to the surface. This movement of alloying elements leads high concentration of these elements at the outmost surface, subsequently the lowest peak of substitutional elements were shown in the vicinity of near surface. After showing the lowest peak, the high concentration region of Al and C were formed due to the continuous movement of Al toward the surface. The long discontinuous precipitates of $Cr_{23}C_6$ and AlN were formed along the outmost surface owing to the high concentration of these alloying elements.

• 대한환경공학회지
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• 제22권4호
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• pp.599-607
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• 2000

본 연구는 연안의 부영양화에 주원인으로 지적되고 있는 비료공장의 질소를 struvite 결정화에 의해 제거하였다. Struvite의 결정화는 $MgNH_4PO_4$의 형태로 알칼리성 용액에는 불용성이다. 여천공단내 N 비료화학폐수는 유기물 및 질소의 농도가 각각 330mg/L 및 550mg/L로 질소의 농도가 높고 유기물의 농도가 낮은 폐수로 물리화학적 전처리없이 기존 생물학적 처리 방법으로는 불가능한 실정이다. 실험은 마그네슘원으로 간수와 $MgCl_2$ 및 $Mg(OH)_2$를 이용하였으며 반응시 미치는 물리화학적 영향인자를 검토하였다. 이때 질소의 제거효율은 각각 71, 81 및 83%이었으며 인의 제거효율은 각각 99, 98 및 93%이었다. 반응시 최적 pH는 10.5~11이었으며, 교반시간 변화에 따른 반응은 매우 신속히 진행되어 2분만에 완료되었다. 따라서 질소 및 인의 제거시에는 간수 및 $MgCl_2$를 이용한다면 짧은 시간에 높은 제거효율의 기대가 가능하며, 소금제조공정의 부산물인 간수의 이용은 화학약품을 대체하여 보다 경제적인 처리방법이 될 수 있다.

• 상하수도학회지
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• 제13권2호
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• pp.34-40
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• 1999

Aerobic night-soil treatment effluent containing high concentration of ammonia nitrogen was treated to remove nitrogen using Bardenpho process with Methanol addition. The objective of this study was to investigate the feasibility of complete nitrogen removal at three different HRTs such as 6.25d, 5d, and 3.75d, respectively. At each HRT, the nitrogen removal efficiencies are 92%, 99% and 97% and the required amount of methanol are 3.05gMeOH/gN, 2.75gMeOH/gN, and 3.38gMeOH/gN, respectively. Specific nitrification rates are decreased proportional to HRT and are $0.022gNH_4^+-N/g\;MLVSS{\cdot}day$, $0.0332gNH_4^+-N/g\;MLVSS{\cdot}day$ and $0.051gNH_4^+-N/g\;MLVSS{\cdot}day$ and specific denitification rate are decreased proportional to HRT and are $0.0210g\;N/gMLVSS{\cdot}day$, $0.0330g\;N/gMLVSS{\cdot}day$ and $0.0525g\;N/gMLVSS{\cdot}day$, respectively.

• 한국식생활문화학회지
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• 제12권1호
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• pp.63-69
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• 1997

This study was carried out in order to analyzed the changes in nitrogen containing taste compounds of three different types of traditional Korean soy sauce with varing ripening period, and to investigates correlation between sensory characteristics and taste compounds contents via contents assay and sensory evaluation of soy sauce samples. Total nitrogen, ammonia type nitrogen and amino type nitrogen contents showed the highest value in Kyupjang. 17 kinds of free amino acid was detected in Chungjangs and 16 kinds of free amino acid was detected in Kyupjang. Nucleotides and their related compounds detected were hypoxanthin, xanthin, IMP, AMP, Inosine, ADP. Free amino acid and nucleotides and their related compounds contents were highest in Kyupjang. Nitrogen related compounds content of high concentration soy sauce ripened over 150 days increased similarly with Kyupjang. In the sensory evaluation of soy sauce taste, Chungjang samples acquired the highest score in the offensive taste test while Kyupjang marked highest score for sweet taste, nutty taste, taste preference. High concentration soy sauce ripend over 150 days yielded the result similar to that of Kyupjang. Sweet taste showed positive correlation with nitrogen compounds. The materials that showed positive correlation with nutty and traditional soy sauce taste and taste preference were nitrogen compound, IMP, AMP. Except for tryptophan, all free amino acid showed positive correlation with nutty and traditional soy sauce taste. Particulary, taste preference correlated to lysine, aspartic acid and glutamic acid.