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        검색결과 231

        1.
        2023.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The binary oxide adsorbent using Fe and Mn (Fe-Mn) has been prepared by precipitation method to enhance the removal of phosphate. Different amounts of chitosan, a natural organic polymer, were used during preparation of Fe-Mn as a stabilizer to protect an aggregation of Fe-Mn particles. The optimal amount of chitosan has been determined considering the separation of the Fe-Mn particles by gravity from solution and highest removal efficiency of phosphate (Fe-Mn10). The application of Fe-Mn10 increased removal efficiency at least 15% compared to bare Fe-Mn. According to the Langmuir isotherm model, the maximum uptake (qm) and affinity coefficient (b) were calculated to be 184 and 240 mg/g, and 4.28 and 7.30 L/mg for Fe-Mn and Fe-Mn10, respectively, indicating 30% and 70% increase. The effect of pH showed that the removal efficiency of phosphate was decrease with increase of pH regardless of type of adsorbent. The enhanced removal efficiency for Fe-Mn10 was maintained in entire range of pH. In the kinetics, both adsorbents obtained 70% removal efficiency within 5 min and 90% removal efficiency was achieved at 1 h. Pseudo second order (PSO) kinetic model showed higher correlation of determination (R2), suggesting chemisorption was the primary phosphate adsorption for both Fe-Mn and Fe-Mn10.
        4,000원
        2.
        2023.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        본 연구에서는 기존 식품첨가물 분석법에서 합으로써 분 석되는 락색소를 laccaic acid A, B, C, E 4가지 성분으로 분류하고 개별적으로 정량 할 수 있는 분석법을 확립하였 다. Natural red 25를 사용하여 구조적으로 비슷한 laccaic acid A와 B를 1차적으로 분취한 후 2차로 A와 B를 분리 했다. 같은 방식으로 C와 D를 1차, 2차에 걸쳐 각각의 개 별 표준품으로 사용하였다. 락색소 불검출 시료 3가지 시료 (햄, 토마토 주스, 고추장)를 확보하여 0.05-107.2 μg/mL 범 위에서 결정계수(r2) 0.995 이상의 직선성을 확인하였다. 3 가지 시료에서 정밀도와 정확성을 측정한 결과, 일내 정 밀도는 0.2-12.3%, 정확도는 90.6-112.7% 범위 내에서 확인 되었으며 일간 정밀도는 0.3-13.3%, 정확도는 90.3-113.0% 범위내로 확인 되었다. 락색소를 사용하는 식품과 사용 금 지 식품에 대해 회수율을 측정한 결과, 사용 가능 식품에서 는 91.6-114.9% 범위의 회수율을 보였으며, 사용 불가 식품 의 경우 92.5-113.5% 범위의 회수율을 보였다. 락색소의 검 출 한계는 3가지 시료에서 검출한계 0.01-0.15 μg/mL, 정량 한계 0.02-0.47 μg/mL로 확인되었다. 락색소의 4가지 성분중 laccaic acid A와 C에 대한 측정 불확도를 산출한 결과, laccaic acid A의 측정 불확도는 13.65±0.39 mg/kg(신뢰수준 95%, K=2), laccaic acid C의 측정 불확도는 4.19±0.39 mg/kg(신뢰 수준 95%, K=2)로 비교적 낮은 측정불확도 값을 산출하 였다. 따라서 본 연구에서는 식품 중 락색소의 개별 분석 과 정성 및 정량분석을 위해 유효성이 검증된 분석법을 확립으로 식품 중 잔류물질 기준규격 설정 및 관리에 참 고 자료가 될 수 있고, 향후 매트릭스 효과에 따른 laccaic acid 개별 분석과 개별 활성 및 독성시험 연구의 근거 지 표가 될 수 있다고 판단된다.
        4,300원
        3.
        2022.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        PURPOSES : In this study, a method to use magnesium phosphate ceramic (MPC) concrete for the surface maintenance of airport pavements with jointed concrete is developed. METHODS : To investigate the application of a material incorporated with MPC for the surface maintenance of airport pavements with jointed concrete, structures with various cross-sections and thicknesses were constructed. The cross-section of the structure was modeled for the surface maintenance of four types of pavements and typical pavement construction processes, such as cutting, cleaning, production and casting, finishing, hardening, and joint reinstallation. Subsequently, the hours required for each process was determined. RESULTS : The MPC concrete used for the surface maintenance of airport pavements with jointed concrete demonstrate excellent performance. The MPC concrete indicates a compressive strength exceeding 25 MPa for 2 h, and its hydration heat is 52.9 ℃~61.2 ℃. Meanwhile, the crushing and cleaning performed during the production and casting of the MPC require a significant amount of time. Specifically, for a partial repair process, a total of 6 h is sufficient under traffic control, although this duration is inadequate for a complete repair process. CONCLUSIONS : MPC concrete is advantageous for the surface maintenance of airport pavements with jointed concrete. In fact, MPC concrete can be sufficiently constructed using existing concrete maintenance equipment, and partial repair works spanning a cross-sectional area of 11 m2 can be completed in 1 d. In addition, if the crushing and cleaning are performed separately from production and construction, then repair work using MPC concrete can be performed at a larger scale.
        4,000원
        4.
        2022.08 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Phosphate coating is applied to the surface of the round bar material used in the multi-stage cold forging process for the purpose of lubrication. The film characteristics are determined according to the conditions of the phosphate film treatment process. In this study, the film properties according to the phosphate treatment conditions were defined as the coefficient of repeated friction and quantitative analysis was performed. Different friction behaviors were exhibited depending on the film properties, suggesting that optimization of the phosphate film treatment conditions is possible based on this. Finally, as a practical example, friction behavior according to the film characteristics was applied to the automotive engine bolt forming process. As a final conclusion, the need for linkage analysis with phosphating conditions for optimizing the forging process was raised. In addition, it can be seen that damage to the phosphate film should be considered in the process of predicting the limiting life of the die.
        4,000원
        5.
        2022.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Spinach (Spinacia oleracea L.), a green leafy vegetable, is well known as a functional food due to its biological activities. Vascular calcification is associated with several disease conditions including atherosclerosis, diabetes, and chronic kidney disease (CKD), and is known to raise the risk of cardiovascular diseases related morbidity and mortality. However, there are no previous studies that have investigated the effects of fermented spinach exract (FSE) against aortic and its underlying mechanisms. Therefore, this study investigated the effects and action of possible mechanisms of FSE on inorganic phosphate (PI)-induced vascular calcification in ex vivo mouse aortic rings. PI increased vascular calcification through calcium deposition in ex vivo aortic rings. FSE inhibited calcium accumulation and osteogenic key marker, runt-related transcription factor 2 (Runx2), and bone Morphogenetic Protein 2 (BMP-2) protein expression in ex vivo aortic rings. And, FSE inhibited PI-induced extracellular signal-regulated kinase (ERK) and p38 phosphorylation in ex vivo aortic rings. These results show that FSE can prevent vascular calcification which may be a crucial way for the prevention and treatment of vascular disease association with vascular calcification.
        4,000원
        7.
        2021.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        A wire rod, a material for multistage cold forging, is subjected to spheroidization and low annealing heat treatment to secure formability, and a phosphate coating treatment on the material surface to secure lubricity. The film layer produced by the phosphate treatment process is involved in adhesion to the material surface, adhesion to the forging die surface, and lubricity. This results in the increase or decrease of the forming load and the increase or decrease of the die life in the cold forging process. In particular, as the cold forging process progresses, the phosphate film is damaged and the original performance is deteriorated, so there is a high possibility of process defects. In case of excessive damage, the film is completely lost and die soldering occurs. Therefore, in this study, quantitative criteria for phosphate film damage are presented and the effect on the cold forging process is analyzed based on this to improve process analysis prediction accuracy. Therefore, in this study, quantitative criteria for phosphate film damage are presented, and based on this, the friction coefficient in the multi-stage cold forging process is to be derived.
        4,000원
        8.
        2021.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The adsorption process using GAC is one of the most secured methods to remove of phosphate from solution. This study was conducted by impregnating Cu(II) to GAC(GAC-Cu) to enhance phosphate adsorption for GAC. In the preparation of GAC-Cu, increasing the concentration of Cu(II) increased the phosphate uptake, confirming the effect of Cu(II) on phosphate uptake. A pH experiment was conducted at pH 4-8 to investigate the effect of the solution pH. Decrease of phosphate removal efficiency was found with increase of pH for both adsorbents, but the reduction rate of GAC-Cu slowed, indicating electrostatic interaction and coordinating bonding were simultaneously involved in phosphate removal. The adsorption was analyzed by Langmuir and Freundlich isotherm to determine the maximum phosphate uptake(qm) and adsorption mechanism. According to correlation of determination(R2), Freundlich isotherm model showed a better fit than Langmuir isotherm model. Based on the negative values of qm, Langmuir adsorption constant(b), and the value of 1/n, phosphate adsorption was shown to be unfavorable and favorable for GAC and GAC-Cu, respectively. The attempt of the linearization of each isotherm obtained very poor R2. Batch kinetic tests verified that ~30% and ~90 phosphate adsorptions were completed within 1 h and 24 h, respectively. Pseudo second order(PSO) model showed more suitable than pseudo first order(PFO) because of higher R2. Regardless of type of kinetic model, GAC-Cu obtained higher constant of reaction(K) than GAC.
        4,000원
        9.
        2020.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Tin bis(monohydrogen orthophosphate) monohydrate 물질의 흡착 성질에 관하여 KCl 수용액을 통하여 조사하였다. 금속이온 농도와 pH를 변화시키면서 어떻게 달라지는지 화학평형에 바탕을 두고 data를 분석하였다. 금속이온들의 흡착 data는 Langmuir 흡착식에 넣어 Langmuir 수치들을 얻는데 사용되었다. Tin phosphate는 산성에서 이온교환 화합물로 작용하였으며, 2가의 전이금속이온에 대해 Cu+2 > Co+2 > Ni+2의 순서로 선택적 흡착성질을 나타내었다. 약한 산성 이온 교환체에서와 같이 금속이온의 교환은 tin phosphate의 선택성을 결정하는데 결정적 역할을 하였다. 모든 경우에서 흡착의 정도는 온도와 농도의 증가와 함께 증가하였다. Lnngmuir 수치들은 흡착과정 동안의 엔트로피, 엔탈피, 자유에너지 변화량같은 열역학적 함수들을 계산하는데 이용되었다.
        4,000원
        10.
        2020.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study investigated the substitution effect of phosphate and isolated soybean powder (ISP) by Allomyrina dichotoma larvae powder (AP) in emulsion sausage. The sausages were prepared for five treatments: 1) positive control (PC): sausages manufactured with sodium pyrophosphate (0.3%) and ISP (1%); 2) negative control (NC): sausages manufactured without sodium pyrophosphate, and ISP; 3) phosphate replacement (PR): sausages manufactured with ISP and AP (1%); 4) ISP replacement (IR): sausages manufactured with sodium pyrophosphate and AP; 5) phosphate and ISP replacement (PIR): sausages manufactured with AP. The 1% AP extract showed DPPH radical scavenging (45.65±2.468%) and metal chelating (22.46±3.559%) activity. The high pH value of AP (8.03) increased the pH of the meat batter of PR, IR, and PIR (p<0.05), but there was no inhibitory effect on cooking loss. Cooking loss of IR was not significantly different with PC due to phosphate. The addition of AP decreased the L* and a* values and increased the b* values, and decreased hardness, chewiness, and springiness of PR, IR, and PIR (p<0.05). AP did not inhibit lipid oxidation in sausages, in contrast to phosphate. In sensory evaluation, the addition of AP resulted in low scores for all sensory parameters of the sausages, although most panels had normal or positive awareness (p<0.05). Aroma was more influential on samples than color. Overall, AP did not replace phosphate and ISP in the sausages. Therefore, processes such as eliminating unique aroma and color and increasing solubility through particle size control are necessary to use AP as a protein source.
        4,200원
        12.
        2020.10 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        Conductive polymer composites with high electrical and mechanical properties are in demand for bipolar plates of phosphoric acid fuel cells (PAFC). In this study, composites based on natural graphite/fluorinated ethylene propylene (FEP) and different ratios of carbon black are mixed and hot formed into bars. The overall content of natural graphite is replaced by carbon black (0.2 wt% to 3.0 wt%). It is found that the addition of carbon black reduces electrical resistivity and density. The density of composite materials added with carbon black 3.0 wt% is 2.168 g/cm3, which is 0.017 g/cm3 less than that of non-additive composites. In-plane electrical resistivity is 7.68 μΩm and through-plane electrical resistivity is 27.66 μΩm. Compared with non-additive composites, in-plane electrical resistivity decreases by 95.7 % and through-plane decreases by 95.9 %. Also, the bending strength is about 30 % improved when carbon black is added at 2.0 wt% compared to non-additive cases. The decrease of electrical resistivity of composites is estimated to stem from the carbon black, which is a conductive material located between melted FEP and acts a path for electrons; the increasing mechanical properties are estimated to result from carbon black filling up pores in the composites.
        4,200원
        14.
        2020.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        2 (Langmuir, Freundlich, Elovich, Temkin, and Dubinin-Radushkevich) and 3 (Sips and Redlich-Peterson)-parameter isotherm models were applied to evaluated for the applicability of adsorption of Cu(II) and/or phosphate isotherm using chitosan bead. Non-linear and linear isotherm adsorption were also compared on each parameter with coefficient of determination (R2). Among 2-parameter isotherms, non-linear Langmuir and Freundlich isotherm showed relatively higher R2 and appropriate maximum uptake (qm) than other isotherm equation although linear Dubinin-Radushkevich obtained highest R2. 3-parameter isotherm model demonstrated more reasonable and accuracy results than 2-parmeter isotherm in both non-linear and linear due to the addition of one parameter. The linearization for all of isotherm equation did not increase the applicability of adsorption models when error experiment data was included.
        4,000원
        15.
        2019.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Among fatty acid families, the polyunsaturated fatty acids were demonstrated to be mediators in various reproductive processes as precursor of steroid hormone (via cholesterol) and prostaglandins (via arachidonic acid), and in the last decade, major research was focused on the effects of omega-6 and especially omega-3 fatty acid. Eicosapentaenoic acid, the longest members of omega-3 fatty acid family, can be produced by a series of desaturation and elongation reactions from shorter member such as α-Linolenic acid. However, very few studies have provided detailed descriptions of Eicosapentaenoic acid effects and mechanisms of action in mammalian oocytes. The purpose of this study was to evaluate the effect of Eicosapentaenoic acid supplementation on in vitro maturation and developmental potential of porcine oocytes. Various concentrations of Eicosapentaenoic acid was added into in vitro maturation medium, and we evaluated the degree of cumulus expansion, nuclear maturation rate, blastocysts quality, and levels of prostaglandin E2, 17β-estradiol, progesterone in the spent medium. High doses (100 mM) of Eicosapentaenoic acid supplementation significantly inhibited cumulus expansion and oocyte nuclear maturation, and prostaglandin E2 synthesis also significantly decreased compared with other groups (p < 0.05). Supplementation of 50 mM Eicosapentaenoic acid showed higher quality blastocysts in terms of high cell numbers and low apoptosis when compared with other groups (p < 0.05), and synthesis ratio of E2/P4 also significantly increased compared with control group (p < 0.05). However, Supplementation of 100 mM Eicosapentaenoic acid showed high apoptosis when compared with other groups (p < 0.05), and synthesis ratio of 17b-estradiol/progesterone also significantly decreased compared with control group (p < 0.05). Our results indicated that supplementation with appropriate levels of Eicosapentaenoic acid beneficially affects the change of hormone synthesis for controlling oocyte maturation, leading to improved embryo quality. However, high doses of Eicosapentaenoic acid treatment results in detrimental effects.
        4,000원
        16.
        2019.08 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Phosphorus is a vital resource for sustaining agriculture and nutrition, but a limited non-renewable resource. Thus, the recovery of phosphorus from waste activated sludge(WAS) was attempted by microwave heating and magnesium ammonium phosphorus(MAP) crystallization. Polyphosphate-accumulating organisms(PAOs) in WAS release phosphate from the cell when they are exposed to high temperature environments. Microwave heating caused phosphorus and ammonia to release from WAS. The amount was increased with increasing temperature, showing that 88.5% of polyphosphate present in the cells were released in the form of phosphate at 80oC. A similar result was also observed in the release of ammonia. On the other hand, both phosphorus and ammonia were crystallized with magnesium, and then was harvested as MAP. Phosphorus recovery rate reached almost 97.8%, but the ammonia was about 13.4%. These results cleary indicate that phosphorus could be recovered from WAS using a physiological trait of PAOs. Heavy metal analyses also show that the MAP crystal is useful and safe as a phosphorus fertilizer.
        4,000원
        17.
        2019.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        인산염 농도 변화에 따른 Hizikia fusiforme의 무기비소 축적량 및 생장률을 분석하였다. 무기비소에 14일간 노출 하였을 때, 2 mg L-1의 높은 인산염 농도에서 무기비소 축적량이 증가하지 않았다. 하지만 인산염 농도가 0.02 mgL-1로 낮은 경우에 무기비소 축적량이 3배 이상 증가하였다. 또한 H. fusiforme는 인산염 농도가 낮은 경우 생장률이 14.5%, 무기비소 (10 μg L-1)에 노출되었을 경우 생장률이 대조구 대비 30% 감소하였다. H. fusiforme는 인산염과 무기비소를 구분하지 못하여 인산염의 농도가 낮은 경우 무기비소 축적량이 증가하게 되고, 축적된 무기비소는 광합성 저해 및 세포분열을 방해하여 생장률을 억제한다. 특히 우리나라의 대표적인 양식생물인 H. fusiforme는 다른 해조류에 비해 상대적으로 무기비소 축적량이 높다고 알려져 있기 때문에, H. fusiforme의 식품안전성을 확보하기 위해 다양한 연구가 필요하다.
        4,000원
        18.
        2019.02 KCI 등재 구독 인증기관 무료, 개인회원 유료
        본 연구는 담녹조강 Tetraselmis suecica와 T. tetrathele의 인산염 흡수에 미치는 발광다이오드의 파장의 영향을 조사하였다. 파장은 청색 발광다이오드(LED; 450 nm), 황색 LED(590 nm), 적색 LED(630 nm) 그리고 형광램프(control)이며, 조도는 100 μmol m-2 s-1로 주사하였 다. T. suecica와 T. tetrathele의 최대흡수속도(ρmax)는 적색 LED에서 6.35 pmol cell-1 hr-1와 9.85 pmol cell-1 hr-1로 나타났으며, 반포화농도(Ks)는 9.43 μM와 21.2 μM로 나타났다. 이는 적색 LED 아래에서 T. suecica와 T. tetrathele가 다른 파장보다 영양염에 대한 친화성이 높다는 것으로 의미한다. 따라서 경제성 및 생산성 향상을 위한 Tetraselmis 배양시스템(광배양기)의 최적 광원은 낮은 영양염 상태에서도 높은 생장속도를 보이는 적색 LED가 적합할 것으로 판단된다.
        4,000원
        19.
        2018.12 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        To improve the etch rate of Si3N4 thin film, H2SiF6 is added to increase etching rate by more than two times. SiO3H2 is gradually added to obtain a selectivity of 170: 1 at 600 ppm. Moreover, when SiO3H2 is added, the etching rate of the SiO2 thin film increases in proportion to the radius of the wafer. In Si3N4 thin film, there is no difference in the etching rate according to the position. However, in the SiO2 thin film, the etching rate increases in proportion to the radius. At the center of the wafer, the re-growth phenomenon is confirmed at a specific concentration or above. The difference in etch rates of SiO2 thin films and the reason for regrowth at these positions are interpreted as the result of the flow rate of the chemical solution replaced with fresh solution.
        4,000원
        20.
        2018.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        벼 이앙기별 인산에 의한 논조류 발생과 제초제에 의한 방제 효과는 다음과 같다. 1. 단작 및 이모작 벼 재배지에서 총출현 종수는 61종으로 녹조류 34종, 규조류 16종, 유글레나 7종, 그리고 남조류 4종이 발생하였고, 녹조류, 규조류는 이모작지가 많았고, 유글레나는 같았으며 남조류는 단작이 많았다. 2. 인산을 이앙전에 50%처리하고 분얼기에 50% 시비하였을 때 총인이 0.06 mg L-1로 가장 높았고, 조류 발생량도 무인산 대비 6월 6일 이앙한 구에서 14.8 mg 20 ml-1으로 3배 이상, 6월 20일에 이앙한 구에서 9.8 mg 20 ml-1 2배 이상 증가하였다. 3. 벼 생육단계별 분얼기, 유수형성기, 그리고 수잉기의 토양 인산의 함량은 관행 및 인산분시별로 유수형성기가 인산의 함량이 116.5~191.8 mg kg-1으로 가장 높은 경향이었으며 무 처리구에서는 15.5~29.1 mg kg-1로 낮았다. 이앙시기별로는 이앙이 빠를수록 높은 경향이었으며, 인산분시별로는 관행에 비해 분시하였을 때 높은 경향을 보였다. 4. 클로로필-a 함량은 6월 6일 이앙한 구에서는 제초제 처리 후 7일에 가장 낮은 6.3 mg m-3 이고, 7월 상순에 무처리구에서 75.8 mg m-3 로 가장 높았다. 6월 20일 이앙한 구에서는 제초제 처리후 7일에 가장 높은 경향이었으며 제초제 처리 후 14일과 21일은 감소하는 경향이었다 5. 논조류 억제율은 quinoclamine이 단작에서 59.2%, 이모 작에는 44.4%로 가장 높았으며, 다음으로 bromobutide + imazosulfuron + pyraclonil > benzobicyclon + mefenacet + peno xsulam >무처리 순이었다.
        4,000원
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