• Fibers and Polymers
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• 제5권1호
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• pp.52-58
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• 2004

Previous investigation results revealed that after the Low Temperature Plasma (LTP) treatment, the hydrophilicity of wool fiber was improved significantly. Such improvement enhances the wool dyeing and finishing processes which might be due to the changes of the wool surface to a more reactive one. In this paper, wool fibers were treated with LTP with different gases, namely, oxygen, nitrogen and gas mixture (25 % hydrogen/75 % nitrogen). Investigations showed that chemical composition of wool fiber surface varied differently with the different plasma gas used. The surface chemical composition of the different LTP-treated wool fibers was evaluated with different characterization methods, namely FTIR-ATR, XPS and saturated adsorption value. The experimental results were thoroughly discussed.

• 한국정밀공학회지
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• 제10권2호
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• pp.138-145
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• 1993

The bath cryostat of cryogenic apparatuses which are generally used to study physical phenomena under low temperature and ultra low temperature has been desigened and constructed. The practical use of the cryostat is verified by the measurement of the storage life of liquid heloum and liquid nitrogen vessels. The cryostat consists of triple structure of high vacuum environment in order to minimize the evaporation rate of liquid helium and liquid nitrogen by thermal conductivity and radiant heat. The minimum thickness which can stand against inner and outer pressures is calculated from considering the strength of the material.

• 한국균학회지
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• 제18권4호
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• pp.181-190
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• 1990

The growth and biochemical activities of Chlorella fusca were studied in the presence of different concentrations of either filtrates or mycelial mats of Saprolegnia ferax and Pythium graminicola. Low concentrations of both fungal filtrates exerted increase in total count, dry weight and in the biosynthesis of photosynthetic pigments, carbohydrates and nitrogen content. High concentrations showed inhibitory effect on both growth and biochemical activities of Chlorella fusca. Supplementation with different concentrations of dry mycelial mats of either fungi the culture of Chlorella showed elevation in biomass, dry weight, and biosynthesis of carbohydrates and nitrogen content especially at low concentrations. The contents of photosynthetic pigment were inhibited only at low concentrations. Neither the culture filtrate of Pythium nor Saprolegnia had cellulolytic activity, although polygalacturonase enzymes were detected, whereas chloroform-extract of both fungal filtrates showed blue spots under long wave light (366 nm).

• 생태와환경
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• 제39권1호통권115호
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• pp.119-130
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• 2006

연속배양의 평형 정상상태 조건에서 담수조류 Microcystis aeruginosa의 최대생장률 (${\mu}_m$)과 세포내 영양염의농도(Q)의 관계, 질소 결핍 상태에서 액체배지에서 영양염 농도(S)와 홉수율(V)의 관계를 각각 조사하였다. 질소제한조건에서 M. aeruginosa의 세포 당 $Q_{0N}$은 0.04 pmol $cell^{-1}$. ${\mu}_m$은 1.1 $day^{-1}$였고, 제한조건에서 최저값 $Q_{0N}$과 충분조건에서 $Q_N$을 탄소기준하여 각각 6.1 ${\mu}mol$ mg $C^{-1}$ 및 9.5${\sim}$12.4 ${\mu}mol$ mg $C^{-1}$였다. 다른 미세조류와 비교f'1면 세포의 질소 함량이 매우 높았고 질소 결핍시에도 그 함량이 높게 유지되어 질소 요구도가 높은 종이었다 질소 제한조건에서 영양염 홉수 측정 결과에서 반포화계수($K_s$)와 최대흡수율 ($V_m$)은 각각 36 ${\sim}$ 61 ${\mu}M$ 및 0.28 ${\sim}$ 0.35 ${\mu}mol\;cell\;{\cdot}\;hr^{-1}$ 범위였다. M. aeruginosa의 $K_5$값은 매우 높았고 $V_m$도 높은 편이었다. $K_s$와 흡수력 $V_m$은 미세조류의 영양상태 즉 영양염의 세포내 함량(Q)이나 제한영양염의 결핍의 강도의 영향을 받고 미세조류 생장균과도 관련이 있다. M. aeruginosa는 다른 미세조류에 비하여 세포내 질소 함량과 생장률이 높기 매문에 질소와 인에 대한 횹수율이 높을 것이다. 그러나 질소 흡수력의 반포화계수 $K_s$값이 높고 $V_m/K_s$비율은 낮아 수게에서 질소가 저농도 일 때에는 다른 미세조류와 비교하면 경쟁력이 떨어지고 질소에 대한 기질 친화력은 약한 것으로 나타났다. 낙동강 하류지역에서 M. aeruginosa가 대발생하는 시기에 수중 영양염의 농도 변동은 M. aeruginosa의 영양생리 kinetics 특성과 잘 부합하는 것으로 나타났다.

• 한국환경농학회지
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• 제19권2호
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• pp.122-127
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• 2000

A stream purification system was applied to the upper reaches of the Masan Reservoir to improve the water quality. This system consisted of two channels which were constructed on both sides of the stream, one side packed with crushed gravels and the other with plastic filter media. The system operated under low pollutant concentrations and high hydraulic loadings during a dry season to avoid clogging of the filter media. Removal rate and efficiency of chemical oxygen demand (COD) in the channel packed with crushed gravel were $14.8g/m^3/d$ and 11.5%, and for the channel with plastic filter media, $50.1g/m^3/d$ and 13.5%, respectively. Removal efficiencies of total phosphorus (T-P) were 6.6% (gravel) and 10.0% (plastic media). These results indicated plastic filter media having relatively high specific surface areas were more efficient than crushed gravels in removing pollutants. However, due to low influent water quality during dry season, the removal efficiencies were low. The proportion of nitrate nitrogen to total nitrogen (T-N) of the inflow was high but, as the system operated under aerobic condition, nitrate nitrogen could not denitrified. Accordingly, total nitrogen was not attenuated with this system. To improve the reservoir water quality effectively, this system should be able to treat the storm runoff containing higher pollutant loadings. When the filter materials are clogged by the storm runoff instead of backwashing, it would be more efficient to replace them, Therefore, the use of natural materials which are light, easily obtaining and replaceable, and have high specific surface areas is recommended.

• 한국토양비료학회지
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• 제10권1호
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• pp.29-37
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• 1977

한국답토양(韓國畓土壤)의 토양질소유효화(土壤窒素有効化) 과정(過程), 산가수분해성유기태질소(酸加水分解性有機態窒素)의 각분별(各分別) Amino acid 조성등(組成等)을 일본토양(日本土壤)과 비교(比較)하여 약우(若于)의 특징(特徵)을 밝혀냈다. 비교(比較)한 일본(日本)의 토양(土壤)은 한국(韓國)과 위도(緯度)에서 거의 같은 위치(位置)이지만 동기(冬期)의 기상조건(氣象條件)이 다르고 또한 점토광물조성(粘土鑛物組成)에도 차이(差異)가 있는 북륙지역(北陸地域)의 토양(土壤)을 사용(使用)했다. 양국토양(兩國土壤)의 전질소함량(全窒素含量)은 거의 같을 것을 공시(供試)했다. 1) 양국(兩國)의 토양(土壤)은 전질소함량(全窒素含量)이 거의 같은 경우(境遇)에 있어서도 무기화율(無機化率)과 무기화양식(無機化樣式) 상이(相異)하며 한국토양(韓國土壤)은 무기화량(無機化量)이 적지만 배양후기(培養後期)에 생성(生成)되는 $NH_4-N$ 양(量)이 비교적(比較的) 많다. 2) 산가수분해성유기태질소(酸加水分解性有機態窒素)의 분별결과(分別結果) 한국토양(韓國土壤)은 전질소(全窒素)에 대(對)하여 가수분해성질소(加水分解性窒素)의 비율(比率)이 적고 특(特)히 ${\alpha}$-amino-N 및 가수분해성(加水分解性) $NH_4-N$가 적다. 그러나 한국답토양(韓國畓土壤)은 Hexosmine의 함유비율(含有比率)이 많고 10% 이상(以上)에 달(達)하는 치(値)를 보이는 경우(境遇)도 있었다. 또한 incubation에 의(依)한 토양질소무기화량(土壤窒素無機化量)과 유기태질소(有機態窒素)의 각(各) 분별(分別)과의 관계(關係)에서는 가수분해성(加水分解性) $NH_4-N$ 및 ${\alpha}$-amino-N의 함량간(含量間)에 유의(有意)한 정상관(正相關)이 있었다. 3) 산가수분해성(酸加水分解性) Amino acid 조성(組成)에서는 답토양(畓土壤)과 밭토양(土壤)(부식질화산회(腐植質火山灰))간(間)에 큰차(差)가 있으며 답토양(畓土壤)은 Basic Amino acid 비율(比率)이 많고 Acidic amino acid가 적다. 또한 한국(韓國)의 답토양(畓土壤)은 Alanine의 함유비율(含有比率)이 일본(日本) 토양(土壤) 보다 적었다. 그 밖에 전질소함량(全窒素含量)의 증가(增加)와 더부러 Proline의 함유비율(含有比率)은 증가(增加)하고 Aspartic acid는 감소(減少)하는 경향(傾向)이였다.

• 한국초지조사료학회지
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• 제15권2호
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• pp.93-100
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• 1995

This experiment was carried out to investigate how to effect the application of nitrogen, phosphate and potassium on the vegetation and dry matter yield in the mixed sward of orchardgrass and crabgrass (Digitaria sanguinalis [L.] Scop.). The experimental sward wa5 consisted of eight plots of non-application, P, K, PK, N. NK, NP and NPK. These plots were sown with seeds mixture of orchardgrass 17.5 kglha and crabgrass 17.5 kg/ ha on 22 April 1975 in the forage experimental field of Kangwon National University, Chunchon, Korea, and were cut four times from 6 July to 18 November 1975. The results obtained were summarized as follows: 1. In orchardgrass density measured after summering, the plot of nitrogen applied without phosphate marked only 3 1.0% of the plot of nitrogen applied with phosphate while in crabgrass density measured at that time the plot of nitrogen applied without phosphate marked as high as 112.5% of the plot of nitrogen applied with phosphate. 2. Application of phosphate and potassium improved wintering record of orchardgrass. In orchardgrass density measured after wintering, the plot of nitrogen applied without phosphate marked only 9.7% of the plot of nitrogen applied with phosphate, and the plot of NP applied without K marked 63.6% of the plot of NP applied with K. 3. In surface coverage of orchardgrass, in midsummer any plot applied with nitrogen regardless of accompanying with or not with phosphate wa5 0%, but in autumn the plot of nitrogen applied with phosphate was 56-58% and the plot of nitrogen applied without phosphate was 5%. While after wintering the plot of nitrogen applied with phosphate was 28-37% though the plot of nitrogen applied without phosphate was only 0.3-0.6%; the application of phosphate improved summering and wintering record of orchardgrass. 4. Application of phosphate demonstrated remarkable effect on increasing dry matter yield in orchardgrass. In year total yield of orchardgrass, the plot of nitrogen applied without phosphate marked as low as 11.3% of the plot of nitrogen applied with phosphate, but in crabgrass the plot of nitrogen applied without phosphate was almost equal to the plot of nitrogen applied with phosphate showing 97.5% of this plot. 5. Application of potassium was not effective on increasing dry matter yield of orchardgrass but its application was effective on increasing dry matter yield of crabgrass. In dry matter yield of orchardgrass significant difference was not found between NP plot and NPK plot, but in dry matter yield of crabgrass NPK plot recorded significantly higher yield compared with NP plot (p<0.05). 6. In botanical composition of the plot of nitrogen applied with phosphate, crabgrass recorded 46.5-50.5% in early summer (July) but in midsummer (August) it dominated the plot recording 85.6-91.2%. 7. In botanical composition based on the year total yield, in the plot of nitrogen applied with phosphate orchardgrass marked 21.7-26.2% and crabgrass recorded 73.8-78.370, but in the plot of nitrogen applied without phosphate orchardgrass marked only 3.5% being overwhelmingly dominated by crabgrass which recorded 96.5%. 8. Application of nitrogen not accompanied with phosphate strengthened competitive power of the crabgrass unilaterally, making orchardgrass be oppressed fatally by the crabgrass.

• Animal Bioscience
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• 제36권11호
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• pp.1718-1726
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• 2023

Objective: The objective of this study was to investigate the effect of supplementation with enzymolytic soybean meal (ESBM) on broilers fed low crude protein (CP) diets. Methods: A total of 360 one-day-old broilers were randomly assigned to six treatments with 6 replicates per treatment and 10 chicks per replicate for a period of 42 days. Chicks were fed a basal standard high-CP diet as a positive control (PC), a low-CP diet (reducing 10 g/kg CP from the PC) as a negative control (NC), or an NC + 0.5%, 1.0%, 1.5%, or 2.0% ESBM diet. Results: Compared to chicks fed the PC, chicks fed the NC had a decreased body weight gain (BWG, p<0.05) from 1 to 42 days, but supplementation with 2.0% ESBM restored BWG (p<0.05) and even linearly improved the feed conversion rate (FCR, p<0.05). Digestibility of CP and ether extract was increased (p<0.05) in chicks fed a 1.0% ESBM diet compared to the PC. With increasing levels of ESBM, nitrogen (N) excretion decreased (p<0.05). The addition of ESBM to the diet did not affect (p>0.05) serum concentrations of total protein, albumin and total cholesterol but led to a descending trend in triglycerides and an ascending trend in calcium and urea N at 42 days (p<0.10). There were no differences (p>0.05) in villus height (VH), crypt depth (CD), and VH/CD (V/C) of the duodenum and jejunum between the PC and NC at both 21 days and 42 days, while increasing dietary ESBM levels linearly (p<0.05) decreased CD and increased V/C of the duodenum and jejunum at both 21 days and 42 days. Conclusion: The findings indicated that ESBM could be used in broiler low-CP diets to improve production performance, decrease N excretion, and enhance intestinal health.

• Journal of Welding and Joining
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• 제18권1호
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• pp.59-69
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• 2000

The purpose of the present study was to investigate weld metallurgical phenomena such as primary solidification mode, microstructural evolution and hot cracking susceptibility in nitrogen-bearing austenitic stainless steel GTA welds. Eight experimental heats varying nitrogen content from 0.007 to 0.23 wt.% were used in this study. Autogenous GTA welding was performed on weld coupons and the primary solidification mode and their microstructural characteristics were investigated from the fusion welds. Varestraint test was employed to evaluate the solidification cracking susceptibility of the heats and TCL(Total Crack Length) was used as cracking susceptibility index. The solidification mode shifted from primary ferrite to primary austenite with an increase in nitrogen content. Retained delta ferrite exhibited a variety of morphology as nitrogen content varied. The weld fusion zone exhibited duplex structure(austenite+ferrite) at nitrogen contents less than 0.10 wt.% but fully austenitic structure at nitrogen contents more than 0.20 wt.%. The weld fusion zone in alloys with about 0.15 wt.% nitrogen experienced primary austenite + primary ferrite solidification (mode AF) and contained delta ferrite less than 1% at room temperature. Regarding to solidification cracking susceptibility, the welds with fully austenitic structure exhibited high cracking susceptibility while those with duplex structure low susceptibility. The cracking susceptibility increased slowly with an increase in nitrogen content up to 0.20 wt.% but sharply as nitrogen content exceeded 0.20 wt.%, which was attributed to solidification mode shift fro primary ferrite to primary austenite single phase solidification.

• 한국습지학회지
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• 제9권1호
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• pp.123-131
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• 2007

Effect of nitrogen-load condition on hydrogen ($H_2$) production and bacterial community in a continuous anaerobic hydrogen fermentation were investigated. The slight $H_2$ production on extremely low nitrogen-load condition (C/N ratio: 180) at the start-up period. The highest $H_2$ production was obtained when the C/N ratio was 36, the $H_2$ production yield ($mol-H_2/mol-glucose$) reached to 1.7, and it was indicated that Clostridium pasteurianum mainly contributed to the $H_2$ production. The $H_2$ production was decreased on both the lower (C/N: 72) and higher (C/N: 18) nitrogen-load conditions. The excess nitrogen-load was not always suitable for the hydrogen production. The fluctuation of $H_2$ production seemed to be caused by a change in the bacterial community according to the nitrogen-load condition, while a recovery of $H_2$ productivity was possible by a control of nitrogen-load condition through the bacterial community change. When the nitrogen-load condition was not suitable for hydrogen production, the lactic acid concentration was increased and also lactic acid bacteria were definitely detected, which suggested that the competition between hydrogen fermentator and lactic acid producer was occurred. These results demonstrated that the nitrogen-load condition affect on the $H_2$ productivity through the change of bacterial community in anaerobic hydrogen fermentation.