• 상하수도학회지
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• 제21권4호
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• pp.429-437
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• 2007

This study aims to develop a sulfur-using denitrification process which is possible a renovation to advanced treatment plant submerging a simple module in activated sludge aeration tank. At first, the impact factor of sulfur-using denitrification was appreciated by the batch test. Secondly, reflecting a dissolved oxygen effect of sulfur-using denitrification that was confirmed by the batch test, in a continuous nitrification/sulfur-using denitrification, high-rate nitrogen removal reaction was induced at optimum condition controlling DO concentration according to phases. Also, inside and outside of sulfur-using denitrification module was covered with microfilter and the module was considered as an alternative of clarifier. Result of batch test for sulfur-using denitrification, $NO_2{^-}N$ was lower for consumption of alkalinity and sulfur than that of $NO_3{^-}-N$. These results revealed the accordance of theoretical prediction. In continuous nitrification/sulfur-using denitrification experiment, actual wastewater was used as a influent, and influent nitrogen loading rates were increased 0.04, 0.07, 0.11, $0.14kg\;N/m^3-day$ by changing hydraulic retention times. At this time, nitrogen loading rates of packed sulfur were increased 0.23, 0.46, 0.69, $0.93kg\;N/m^3-day$. As a result, nitrification efficiency was about 100% and denitrification efficiency was 93, 81, 79, 72%. Accordingly, nitrogen removal was a high-rate. Also the module of sulfur-using denitrification covered with microfilter did not make a fouling phenomena according to increased flux. And the module was achieved effluent suspended solids of below 10 mg/L without a clarifier. In conclusion, it is possible a renovation to advanced treatment plant submerging a simple module packed sulfur in activated sludge aeration tank of traditional facilities. And the plant used the module packed sulfur is expected as a effective facilities of high-rate and the smallest.

• 열처리공학회지
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• 제13권5호
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• pp.337-345
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• 2000

As a case hardening process for stainless steels, nitriding is more preferred and widely used than carburizing which deterioates corrosion resistance severely. In order to add the nitrogen into the stainless steels, passive film on the surface must be removed effectively before nitriding. Conventional gas nitriding process is performed in the temperature range of 500 to $600^{\circ}C$ with $NH_3$ gas, which often leads to sensitization of stainless steels. In this study, we tried to activate passive film of austenitic stainless steels by heating at low pressure. ($900^{\circ}C$, $5{\times}10^{-2}$ Torr.) Nitriding was performed at the solution treatment temperature of $1100^{\circ}C$ with nitrogen molecules instead of $NH_3$ gas. An attainable nitrogen content in a case depends on the nitrogen gas pressure at constant nitriding temperature. A case depth is proportional to the square root of solution time, which suggests that inward diffusion of nitrogen follows the Fick's 2nd law. Surface nitrogen atoms are dissolved as interstitial solutes, or precipitated in the form of MN, $M_2N$ nitrides, which increase the case hardeness. Dissolved nitrogen in the case enhances the cavitation resistance of austenitic stainless steels dramatically.

• 한국초지조사료학회지
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• 제12권4호
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• pp.239-245
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• 1992

Aspects of nitrate accumulation of forages growing on grasslands in Chonbuk Province, and the effects of different rates of N fertilizer on the total nitrogen and nitrate contents of sudangrass-hybrid and corn were studied through the 1991 growing season. The results obtained are summarized as follows: I . Thc nitrate content of the forages was increased by N application and decreased as the plants matured. 2. Nitrate concentration was high throughout the growing season in samples collected at Namweon-gun 1, which was considered as potentially unsafe. 3. Total nitrogen and nitrate content of plants generally increased with the increasing rates of N fertilizer, but not statistically significant among treatments except the plot of 25 kg N/lOa. 4. The annual crops had a greater tendency to accumulate nitrate than the perennial forage species. 5. It is suggested that high level of N fertilizer and manure may result in toxic levels of nitrate, and special attention must be given in feeding them.

• Asian-Australasian Journal of Animal Sciences
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• 제3권3호
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• pp.165-175
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• 1990

This experiment was conducted to examine the effects of different carbohydrate and nitrogen source upon the utilization of amino acids in the small intestine of sheep. The results obtained are as follows: 1) For the quantities of total amino acid-N(TAA-N), essential amino acid-N(EAA-N) and nonessential amino acid-N(NEAA-N) passing at the duodenum and ileum except NEAA-N passing at the ileum were no significant differences (p>0.05) between diets. The quantities of NEAA-N passing at the ileum for the diets containing meat and bone meal were significantly higher (p>0.05) than the diets containing soybean meal. The mean values for the proportionate disappearance apparently digested TAA-N, EAA-N and NEAA-N within the small intestine for four diets were $0.692{\pm}0.0449$, $0.702{\pm}0.0132$ and $0.682{\pm}0.726$, respectively. 2) There were no significant differences (p>0.05) in duodenal individual amino acid flow between diets with the exception of aspartic acid and glycine. The amounts of each amino acid in duodenal digesta, expressed as a proportion of the amounts ingested for the four diets, were shown that there were net gains of EAA with the exception of arginine and NEAA with the exception of glutamic acid, glycine and praline prior to the small intestine. 3) Within the small intestine, there were no significant losses of each EAA (p>0.05) but significant losses of aspartic acid and glycine of NEAA between diets (p<0.01). The mean values of the proportionate losses of methionine, alanine and lysine within the small intestine were $0.816{\pm}0.04$, $0.767{\pm}0.04$ and $0.732{\pm}0.01$, respectively.

• 한국농림기상학회지
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• 제24권4호
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• pp.285-294
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• 2022

본 연구에서는 벼 재배 부문 질소 비료 시용에 따른 N₂O 배출량 평가를 위해 경기도 화성시 경기도농업기술원 내 벼논에서 폐쇄형 챔버법으로 측정하였으며, 미량의 N₂O 배출량이 과소평가되지 않도록 현장 측정 플럭스 자료에 대한 방법검출한계(MDL; Method Detection Limit)와 실용정량한계(PQL; Practical Quantitation Limit)를 산정하고 이를 바탕으로 QA/QC 방법을 설정하여 원시자료와 QA/QC 방법을 수행한 N₂O 배출량을 비교하였다. 벼 재배 표준시비량인 3요소 N-P₂O₅-K₂O = 90-45-57 kg ha^-1 기준 질소 0배, 1배, 1.5배, 2배로 4처리하여 평가한 N₂O 배출량 변화에서는 N₂O 배출량이 가장 적었던 질소 0배 처리구 외에는 원시자료와 QA/QC 방법을 수행한 자료 모두 유의한 차이가 없었으며, 질소 비료 시용량이 많을수록 N₂O 배출량이 높게 나타나 질소 1배 처리구 대비 질소 2배 처리구는 191% 높게 나타났다. 질소 시비량에 따른 N₂O 배출량의 회귀관계 분석에서는 지수회귀모형에서 결정계수가 가장 높았으며, 선형회귀모형으로 산정한 기본배출계수는 IPCC에서 제공하는 기본배출계수 값과 동일하게 나타났다. 본 연구결과는 농업부문 온실가스 배출량 산정을 위해 보편적으로 사용하고 있는 폐쇄형 챔버법의 플럭스 자료에 대한 QA/QC 방법을 제시하고, 원시자료와의 비교분석을 통해 질소 비료 시비에 따른 벼논에서 발생하는 N₂O 배출량에 대한 신뢰성 있는 평가가 가능한 것으로 판단할 수 있다.

• Asian-Australasian Journal of Animal Sciences
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• 제22권3호
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• pp.371-377
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• 2009

The objectives of the present study were to investigate the effects of different dietary ratios of whole-crop corn silage and alfalfa hay on nitrogen (N) digestion, duodenal flow and metabolism across the portal-drained viscera (PDV) of growing beef steers, and to elucidate their relationships. Four steers (236${\pm}$7 kg BW) fitted with duodenal cannulae and chronic indwelling catheters into the portal and mesenteric veins and abdominal aorta were used in a 4${\times}$4 Latin square design. Animals were fed (at 12-h intervals) the 4 diets consisting of whole-crop corn silage (C) and alfalfa hay (A) in 80:20 (C8A2), 60:40 (C6A4), 40:60 (C4A6) and 20:80 (C2A8) ratios of which dietary crude protein (CP) was 10.5, 12.0, 13.5 and 15.0% of dry matter (DM), respectively. Feeding level was restricted to 95% of ad libitum intake to measure N digestion, blood flow and net flux of N across the PDV. Digestibility of DM and neutral detergent fiber and digestible energy intake linearly increased as the ratio of alfalfa hay increased. The N intake, duodenal flow and intestinal disappearance increased linearly with increasing alfalfa hay. Arterial and portal concentrations of ${\alpha}$-amino N showed a quadratic response to increasing levels of alfalfa hay and were the highest in steers fed the C6A4 diet. The net PDV release of ${\alpha}$-amino N and ammonia N increased linearly with increasing alfalfa hay, but urea N uptake by PDV did not differ among diets. As a percentage of apparently digested N in the total gut, net PDV release of ${\alpha}$-amino N linearly decreased from 66 to 48% with increasing alfalfa hay. Conversely, net PDV recovery of ${\alpha}$-amino N to intestinal N disappearance varied with increasing alfalfa hay accounting for 49, 50, 58 and 61% on C8A2, C6A4, C4A6 and C2A8 diets, respectively. Net PDV uptake of urea N, relative to apparently digested N, linearly decreased from 81 to 25% as alfalfa hay increased from 20 to 80% of DM intake. Considering PDV uptake of urea N, microbial efficiency and conversion of total tract digested N to PDV ${\alpha}$-amino N net supply, a diet consisting of 80% whole-crop corn silage and 20% alfalfa hay (10.5% CP) was the best, while considering the quantities of intestinal N disappearance and ${\alpha}$-amino N absorption, a diet of 20% whole-crop corn silage and 80% alfalfa hay (15% CP) would be preferred. The proportion of ${\alpha}$-amino N recovered by PDV relative to the intestinal N disappearance may vary with energy intake level of mixed forage diets.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1993년도 하계학술대회 논문집 B
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• pp.1295-1297
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• 1993

Properties of oxynitride films oxidized by $N_2O$ gas after thermal oxidation and $N_2O$ oxide films directly oxidized using $N_2O$ gas on the bare silicon wafer have been studied. Through the AES analysis, Nitrogen pile-up at the interface of Si/oxynitride and Si/$N_2O$ oxide has observed. Also, it could be presumed that there are differences in the mechanism of the growth of film by observing film growth. $N_2O$ oxide and oxynitride films have the self-limited characteristics. Therefore, it will be possible to obtain ultra-thin films. Nitrogen pile-up at the interfaces Si/oxynitride and Si/$N_2O$ oxide strengthens film structure and improves dielectric reliability. Although fixed charge densities and interface trap densities of $N_2O$ oxide and oxynitride films has somewhat higher than those of thermal $SiO_2,\;N_2O$ oxide and oxynitride films showed improved I-V characteristics and constant current stress.

• 한국초지조사료학회지
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• 제8권1호
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• pp.40-46
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• 1988

This study was carried out to determine the effects of nitrogen (N) fertilization levels (0, 100 and 200kg/ha) and formaldehyde (0.4,0.8 and 1.2%: w/w CM) on the chemical composition, dry matter (DM) yield and in-vitro dry matter digestibility (IVDMD) of forage rape (Brassica napus Subsp. oleifera) silage. The results obtained are summarized as follows : 1. Forage rape was a catch crop which was highly digestible and low concentration in NDF, ADF, cellulose and lignin. 2. The concentration of the water soluble carbohydrate (WSC) and buffering capacity (PK) was 17.9% and 6.77g/100g, respectively, provided the WSC to PK ratio was 2.65. 3. DM content of silage decreased as the rate of N fertilization increased, but concentration of ammonia-N decreased. IVDMD was not affected by the rate of N fertilization. 4. By the addition of formaldehyde, the pH and IVDMD were increased, but the DM, lactic acid, total organic acid and ammonia-N content of rape silage were decreased, that was effective as a silage additive for forage rape.

• 한국작물학회:학술대회논문집
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• 한국작물학회 2017년도 9th Asian Crop Science Association conference
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• pp.190-190
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• 2017

Chemical fertilizers have been used to increase crop production and contributed to escaping food shortages. However, excessive use of chemical fertilizers over a long period caused many problems such as environmental pollution and the hampered production potential of the land. Thus, it is necessary to develop eco-friendly bio-fertilizers that can replace the use of chemical fertilizers. Here, we tested the effect of some nitrogen-fixing microorganims on the plant growth promotion. Seventy free-living nitrogen fixing microorganisms were isolated from rhizosphere of crop cultivation fields, streamside soils and sludge in Ansung, Korea. Of them, three strains (NF2-4-1, Yeast; EMM409, Mesorhizobium; Gsoil662, Burkholderia) were selected to be most efficient in the capacity of N-fixing nitrogen based on colony forming cell assay in N-free media. To investigate the ability to promote plant growth, these strains were inoculated into the soil and cabbage were grown for 4 weeks in the grown chamber. Fresh weight, dry weight, and leaf area were measured from 4-week-old plants. Phenotypic analysis revealed that the growth of the plants inoculated with NF2-4-1 and EMM409 strains were significantly promoted compared to the mock-treated control plants, while Gsoil662-inoculated plants did not show statically significant promotion. These results indicate that these nitrogen-fixing microorganims can be used to develop plant growth promoting bio-fertilizers. Further analysis on nitrogen fixing level in soil by these strains will be tested.

• Environmental Engineering Research
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• 제24권2호
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• pp.238-245
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• 2019

This study investigated the characteristic of aerobic granular sludge (AGS) process to treat the sewage having low carbon/nitrogen ratio (Biochemical oxygen demand ($BOD_5$):Total nitrogen (T-N), 4.5:1) in sequencing batch reactor (SBR). The removal efficiency of $BOD_5$, suspended solid (SS), T-N and phosphorus ($PO_4{^{3-}}$-P) were 92.6%, 64.3% and 90.1%. Concentration and size of AGS were changed in proportion to the organic matters and nitrogen concentration of the influent (Concentration and size of AGS: 1,700-3,000 mg/L, 0.5-1.0 mm). Mixed liquor suspended solid (MLSS) also changed with the concentration of AGS (MLSS: 2,000-3,500 mg/L). When the settling time was shortened from 15 min to 10 min, size and shape of AGS were maintained (Size of AGS: 1.0-1.5 mm). In addition, the concentration of AGS and MLSS increased (Concentration of AGS: 3,500 mg/L, MLSS: 4,000 mg/L). Concentration, size and shape of AGS were affected the settling time of the reactor more than the concentration of organic matter and nitrogen in the influent. In the results of removal efficiency and changes in AGS, we confirmed that the SBR process using AGS can be used to treat the sewage having low carbon/nitrogen ratio by applying short settling time.