• 한국농공학회논문집
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• 제60권3호
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• pp.107-112
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• 2018

In this study, we conducted to analyze and quantify the amount of nitrogen supply into the rice paddies from the rainfall during cropping and non-crop periods. Rainfall monitoring conducted 85 times from June 2015 to December 2017. Nitrogen supply of cropping season ranged from 5.37 to 7.70 kg/ha, while non-cropping season were supplied from 3.97 to 4.42 kg/ha. The supply of T-N in the crop period was more than 60% of the total supply. And as a result of analyzing the correlation between the characteristics of rainfall and the supply amount, nitrogen concentrations in rainfall were decreased with increasing rainfall, but the supply amount was increased. Therefore, efforts should be made to increase the rainfall utilization and to increase the nitrogen supply of crops by increasing rainfall storage through drainage management.

• 한국토양비료학회지
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• 제47권6호
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• pp.547-552
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• 2014

This study was conducted to evaluate the influence of fertilization on characteristics of growth and accumulation of anthocyanin in fruit of Omija (Schisandra chinensis Baillon). Nitrogen supply mainly affected growth of fruit and the anthocyanin content in Omija respective of vegetative growth steps. The anthocyanin content in fruit was significantly low in high N supply and non-fertilization. The conjunctive supply of nitrogen and compost tea resulted in a higher anthocyanin content of fruit, total nitrogen content of leaf, and nitrate in soil. This result implies that nitrogen supply to Omija plant, affects the accumulation patterns of anthocyanin in different ways, e.g. it delays the quantitative biosynthesis at low nitrogen supply during fruit maturation or enhances anthocyanin degradation during the final maturation steps.

• 항공우주시스템공학회지
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• 제14권5호
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• pp.26-32
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• 2020

본 연구에서는 액체로켓 연소기의 연소 불안정 모사를 위해 극저온 유체인 액체질소를 공급하는 설비를 구축하였다. 가압 및 공급 성능을 예측하였으며 실험을 통하여 검증하였다. 액체질소 공급 시스템은 가압식 공급 시스템으로 구성하였으며, 가압제 압력 조정은 돔 레귤레이터를 사용하였다. 액체질소 공급 유량 제어는 캐비테이션 벤추리를 사용하였으며, 액체 질소 공급 조건은 초당 유량 2.55 kg/s, 벤추리 입구 압력은 100 bar 이상이다. 초기 실험 결과 예측된 가압제의 양이 충분히 공급되지 못하여, 탱크압력 강하가 발생해 목표 유량을 공급하지 못하였다. 구축된 설비의 변경 및 보완을 통하여, 최종적으로 목표 유량 공급에 성공하여 극저온 액체질소 공급 설비를 검증하였다.

• 한국추진공학회지
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• 제15권2호
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• pp.68-73
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• 2011

소형위성발사체 (KSLV-I)의 발사 준비에는 다양한 규격의 질소 가스 및 초저온 액체 질소가 소요된다. 발사대 질소 공급 시스템은 고압의 질소 가스 생성, 추진제 충전 후 발사 대기 중인 발사체의 보호를 위한 공간 퍼지용 질소 가스 생성, 연료 및 산화제의 냉각을 위한 액체 질소 공급 기능을 수행하기 위하여 개발되었다. 대기 환경 조건에 따라 열전달 특성이 민감하게 변화하는 대기식 기화기의 운용 불안정성을 제거하기 위해 기화기의 병렬 설치 및 교대 운용 절차를 도입하였다. 이를 통하여 기후 조건에 상관없이 항시적으로 운용이 가능한 시스템을 개발하였으며, 소형 위성 발사체의 비행 시험을 위한 발사대 운용을 성공적으로 수행하였다.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2010년도 제35회 추계학술대회논문집
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• pp.752-757
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• 2010

소형위성발사체 (KSLV-I)의 발사 준비에는 다양한 규격의 질소 가스 및 초저온 액체 질소가 소요된다. 발사대 질소 공급 시스템은 고압의 질소 가스 생성, 추진제 충전 후 발사 대기 중인 발사체의 보호를 위한 공간 퍼지용 질소 가스 생성, 연료 및 산화제의 냉각을 위한 액체 질소 공급 기능을 수행하기 위하여 개발되었다. 대기 환경 조건에 따라 열전달 특성이 민감하게 변화하는 대기식 기화기의 운용 불안정성을 제거하기 위해 기화기의 병렬 설치 및 교대 운용 절차를 도입하였다. 이를 통하여 기후조건에 상관없이 항시적으로 운용이 가능한 시스템을 개발하였으며, 소형 위성 발사체의 비행 시험을 위한 발사대 운용을 성공적으로 수행하였다.

• Journal of Microbiology and Biotechnology
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• 제5권2호
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• pp.100-104
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• 1995

Production of $poly-{\beta}-hydroxybutyrate$ (PHB) in a strain of Azotobacter chroococcum, a nitrogen-fixing bacteria, was investigated at various levels of nitrogen and oxygen. Feeding nitrogen source increased both cell growth and PHB accumulation. Oxygen supply appeared to be one of the most important operating parameters for PHB production. Both cell growth and PHB accumulation increased with the sufficient supply of air in the fed-batch fermentation of the strain. However, it was also noted that keeping the oxygen level under limited condition was critical to achieve high PHB productivity. A high titer of PHB (52 g/l) with a high cellular content (60%) was obtained after 48 hr of fed-batch operation by controlling the oxygen supply. Dual limitation of nitrogen and oxygen did not further increase the PHB accumulation probably due to the greater demand for reducing power and ATP for nitrogen fixation.

• The Korean Journal of Ecology
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• 제19권4호
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• pp.341-351
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• 1996

In order to elucidate the differences in early successional development among similary aged old-fields having different soil nitrogen (N), caused by the land use history before at abandonment, the response of plant community along an experimental nitrogen gradient (control plot (No), plot NI with 5.8g $N/m^2$, plot N2 with 11.7g $N/m^2$ and plot N3 with 23.3g $N/m^2$) was investigated in a five-year-old abandoned field. Although the N content in soil among treatments was similar at the end of the growing season, N concentrations in plant tissue increased with the amount of N supplied. These results suggest that almost all the N contained in N-enriched soil might be absorbed by plants during the growing season after N supply. Vegetation tended to grow vigorously by nitrogen supply, and the standing biomass increased significantly in plots NI and N2 . Species richness of plants, especially of annuals and perennials, was more reduced than the control plot, and the species diversity was also reduced by N supply. The importance value (IV) of species by N supply differed in each species along the position on the successional sere: Artemisia princeps var. orientalis as the dominant species in this old-field decreased slightly; annuals as the earlier successional species decreased clearly along nitrogen gardients; Erigeron annuals as the earlier successional species and as a strong competitor with Artemisia princeps var. orientalis had the highest IV by small N supply; Miscanthus sinensis and Rubus crataegifolius as the later successional species increased by large N supply. These results suggest that old-fields with high soil N might show the structural and functional characteristics of the earlier successional stages, but community composition in those old-fields might be changed more quickly from the sarlier successional species than the later successional species.

• 생물환경조절학회지
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• 제15권1호
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• pp.84-90
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• 2006

This study was conducted to anticipate nitrate reduction state in tree through measurement of nitrate reductase activity (NRA) and investigate the effect of nitrogen concentrations (100, 200, 400, and 600 $mg\;L^{-1}$) on growth, the nitrogen content of various tissue, and NRA of pear (Pyrus pyrifolia cv. Niitaka) seedlings in sand culture. Nutrient solutions used in this experiment were adjusted to pH 6.5 and fixed the ratio of ammonium and nitrate to 1:3 and trickle-irrigated 3 times a day. Tree height and dry weight of various organs in seedlings were higher in low nitrogen concentration (100 and 200 $mg\;L^{-1}$) than in high nitrogen concentration (400 and 600 $mg\;L^{-1}$). The shoot growth in 600 $mg\;L^{-1}$ was extremely poor by nitrogen over supply. Increasing the nitrogen concentration, the concentration of nitrate-N in leaves and roots were insignificantly changed but that of stems increased. The accumulation of total and reduced nitrogen in all organs with increasing concentrations of nitrogen supply were increased at 30 days after treatment but those of all organs at 60 and 90 days after treatment were highest in 600 $mg\;L^{-1}$, whereas there were no significant changes among other nitrogen concentration. The in vivo (${+NO_3}^-$) NRA of all organs did not relate to nitrogen concentration but the in vivo (${-NO_3}^-$) NRA of leaves except roots increased with increasing the nitrogen concentration. Therefore, the proper nitrogen concentration to promote growth and nitrate reduction of pear tree was 200 $mg\;L^{-1}$.

• 농업과학연구
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• 제42권4호
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• pp.431-437
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• 2015

자원순환 및 친환경 농업을 실천하는 농가가 증가함에 따라 유기물을 활용한 농경지 양분관리에 대한 필요성이 대두되고 있다. 질소 공급원으로 유기물을 시용했을 때 질소 공급효과에 대한 연구들을 정리한 결과는 다음과 같다. 농경지에 유기물을 시용했을 때 질소의 공급은 질소 순환에서 무기화 과정을 통해 이루어지기 때문에 작물의 단기적인 질소 이용률은 무기질 비료에 비해 낮다. 유기물의 질소 공급량은 유기물의 C/N율이 낮을수록 무기화율이 높아지므로 C/N율을 고려한 유기물 시용이 중요하다. 가축분 퇴비의 경우 축종별 분뇨 질소함량과 퇴비와 혼합된 부산물 종류에 따라 질소 무기화율이 달라질 수 있으며, 녹비는 작물 종류와 환원시기, 토양 양분조건 등에 따라 C/N율이 달라진다. 또한 적정량의 질소를 추천하기 위해서는 토양 중 유기태 질소로부터 가용화 될 수 있는 질소의 양을 측정하여야 한다. 지금까지 보고된 퇴비, 녹비에 대한 질소공급과 작물 생산성에 대한 연구결과는 재배 여건과 작물 종류 등에 따라 다르게 나타나 질소 공급을 위한 유기물 추천 모델을 구성하기 위한 기초자료로 활용하기에는 어려움이 있다. 유기물 추천 모델을 구성하기 위해서는 우선적으로 유기물질 종류별 질소 공급량에 대한 기초 데이터가 구축되어야 하며, 토양의 질소공급량을 평가할 수 있는 분석 방법의 구축이 필요하다.

• Journal of Plant Biology
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• 제14권4호
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• pp.5-13
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• 1971

Pot and paddy field tests were conducted to study red discoloration of rice var. IR 667 leaves with reference to the leading Korean native variety Jinhung and Paldal, with the following results: 1. Minor elements such as Mn, Fe, B, Al, Ca and Si had no influence on the discoloration, but a supply of various soluble nitrogen compounds completely restricted it. The more prosperous the growth of IR 667 with nitrogen, the more severe the discoloration appears when nitrogen absorptin becomes limited. 2. Chlorotic pigments extracted from both IR 667 and Jinhung were compared spectrophotometrically, and found to have different spectral peaks. IR 667 had peak closer to red than Jinhung, indicating the characteristic of the variety. IR 667 was observed to be more sensitive to nitrogen deficiency than Jinhung or the other japonica variety. 3. It was concluded that all the factors limiting nitrogen supply for IR 667 growth, such as low nitrogen application, restriction of root respiration (low temperature, poor drainage, toxic gases or substances in the root zone, etc.) and pest injuries, would result in the appearance of the so-called red discoloration, because of the reduction in nitrogen uptake. Since, the discoloration of IR 667 is varietal characteristic when grown in Korea, control of it may be beneficial cultural practice in increasing grain yield, although the increased succeptibility to pests and a drop in the rate of maturity due to relatively high nitrogen level in the leaves may result in an unexpected drop in yield. It is anticipated that further exploration conducted from practical point of view will establish the relatioknships between the extent of red discoloration, nitrogen availability and grain yield in IR 667.