• 한국자동차공학회논문집
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• 제22권4호
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• pp.152-159
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• 2014

Urea solution as a reductant of SCR has been widely used to reduce NOx emissions from diesel engine. But it has lots of problems which are freezing at low temperature due to liquid state, deposition of solid formation in the exhaust, dosing device, and complex package such as mixers for uniform concentration of ammonia. In order to overcome these obstacle, ammonium carbonate which is one of solid ammonium materials to produce ammonia gas directly by sublimation process is considered. Simple reactor with visible widow was designed to predict equilibrium temperature and pressure of ammonium carbonate. To simulate real operation conditions under automobile environment, several cycles of heating and cooling condition were settled, two different re-solidification materials were extracted from the reactor and visible window. Analytical study is performed to characterize these unknown materials by XRD(X-Ray Diffraction), FT-IR(Fourier Transform Infrared Spectroscopy), and EA(Elemental Analyzer). From analytical results, re-solidification materials from heating and cooling cycles are very similar to original material of ammonium carbonate.

• 대한약침학회지
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• 제17권3호
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• pp.7-15
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• 2014

Objectives: The present study investigated the toxic properties of petroleum ether extract of Wattakaka (W.) volubilis in Wistar female rats. Methods: An in vitro brine shrimp lethality bioassay was studied in A. Salina nauplii, and the lethality concentrations were assessed for petroleum ether extract of W. volubilis. A water soluble portion of the test extract was used in different concentrations from $100-1000{\mu}g/mL$ of 1 mg/mL stock solution. A 24-hours incubation with a 1-mL aliquot in 50 mL of aerated sea water was considered to calculate the percentage rate of dead nauplii with test extract administration against a potassium-dichromate positive control. The acute and the sub-acute toxicities of petroleum ether extract of W. volubilis were evaluated orally by using gavage in female Wistar rats. Food and water intake, body weight, general behavioral changes and mortality of animals were noted. Toxicity or death was evaluated following the administration of petroleum ether extract for 28 consecutive days in the female rats. Serum biochemical parameters, such as alanine aminotransferase (ALT), alkaline phosphatase (ALP), bilirubin, total cholesterol, triglyceride, total protein, glucose, urea, creatinine, sodium, potassium and ${\alpha}$-amylase levels, were measured in the toxicity evaluations. Pathological changes in isolated organs, such as the liver, kidneys, and pancreas, were also examined using hematoxylin and eosin dye fixation after the end of the test extract's administration. Results: The results of the brine-shrimp assay indicate that the evaluated concentrations of petroleum ether extract of W. volubilis were found to be non-toxic. In the acute and the sub-acute toxicity evaluations, no significant differences were observed between the control animals and the animals treated with extract of W. volubilis. No abnormal histological changes were observed in any of the animal groups treated with petroleum ether extract of W. volubilis. Conclusion: These results suggest that petroleum ether extract of W. volubilis has a non-toxic effect in Wistar female rats.

• Bulletin of the Korean Chemical Society
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• 제25권8호
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• pp.1177-1181
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• 2004

The determination of uric acid in urine samples was studied by a chemiluminescence measurement using tris (2,2'-bipyridine)ruthenium(II)-octylphenylpolyglycolether [Ru$(bpy)_3^{2+}$ -OPE] system. The oxidized uric acid by Ce(IV) excited Ru$(bpy)_3^{2+}$ to emit a chemiluminescence in this system so that the intensity was stoichio-metrically dependent upon the concentration of uric acid. In a reaction cell, a luminescent reagent, oxidant, surfactant and sulfuric acid were flowed into and mixed with a taken sample. Experimental conditions were optimized to obtain the maximum intensity of chemiluminescence. Each reactant solution of more than the following concentration gave a good result: $2\;{\times}\;10^{?4}$ M Ru$(bpy)_3^{2+}$ , 0.01 M Ce(IV), 6% OPE, and 0.33 M $H_2SO_4$. Any interferences were not shown in this process by the investigation of concomitant constitutes such as albumin, creatine, lactic acid, glucose, urea, $Cl^?,\; Mg^{2+},\;Ca^{2+}$ and so on. The linearity of a calibration curve was good with r = 0.998, the relative standard deviation of the slope was 3.3% and the detection limit was 5.6ng/mL. The recoveries of 80 to 91% were obtained from the standard spiked samples. The values were little bit low, but this procedure could be considered to be reliable for the determination of trace uric acid in urine samples.

• 한국가스학회지
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• 제15권2호
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• pp.21-26
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• 2011

대형경유차는 수량이 적음에도 불구하고 높은 운행 빈도로 인해 대기오염물질의 높은 비율을 차지하고 있다. 이에 대한 해결책으로 저공해 자동차인CNG(CompressedNatural Gas)버스가 대두되고 있다. CNG차량의 배출가스는 경유에 비해 PM이나 NOx가 크게 감소되는 경향을 보인다. 본 연구에서는 친환경 연료인 CNG에 수소를 혼합한 연료를 이용한 차량에서의 배기가스 후처리 기술에 대해 소개한다. CNG에 수소를 혼합함으로써, 엔진의 연소 효율은 올리고 배기가스를 감소시킬 수 있으나, CNG의 주성분인 메탄 역시 온실가스로서 이에 대한 저감도 필요한 실정이다. CNG엔진에서 배출되는 메탄에 대해 CNG산화촉매를 도입하여 저감 방향을 설정하였으며, 발생하는 NOx에 대해서는 urea-SCR 및HC(HydroCarbon)-SCR을 도입하였다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회B
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• pp.2874-2879
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• 2008

The Selective catalytic reduction(SCR) system is a highly-effective device of $NO_x$ reduction for diesel engines. Generally, the ammonia($NH_3$) generated from a liquid urea-water solution is used for the reductant. The ideal ratio of $NH_3$ molecules to $NO_x$ molecules is 1:1 based on $NH_3$ consumption and having $NH_3$ available for reaction of all of the exhaust $NO_x$. However, under the too low and too high temperature condition, the $NO_x$ reduction efficiency becomes lower, due to temperature window. And space velocity also affects to $NO_x$ conversion efficiency. This paper reviews a laboratory study to evaluate the effects of $NO_x$ and $NH_3$ concentrations, gas temperature and space velocity on the $NO_x$ conversion efficiency of the SCR system. The maximum conversion efficiency of $NO_x$ was indicated when the $NH_3$ to $NO_x$ ratio was 1.2 and the space velocity was $60,000\;h^{-1}$. The results of this paper contribute to improve overall $NO_x$ reduction efficiency and $NH_3$ slip.

• KSBB Journal
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• 제16권2호
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• pp.146-152
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• 2001

rhGH-GST 융합단백질을 사용하여 재조합 대장균 세포 파쇄액으로부터 직접적으로 내포체의 solid-phase 재접힘을 수행할 수 있는 새로운 공정을 개발하였다. 그것은 고체 업자를 제거하는 동시에 초기에 목적딴백질을 흡착 포집할 수 있 는 expanded bed adsorption 크로마토그래피의 장점을 이용한 것이다. 세포 파쇄액 내 용해훤 내포체로부터의 풀린 융합단백질은 expanded bed adsorption 원리에 의해 STREAMLINE DEAE resin에 흡착되고 세포 찌꺼기 등 고체 입자물들은 위 방향 흐름에 의해 효과적으로 제거된다. Urea를 접차적으로 제거함으로써 융합단백질은 고체 matrix 표면에서 재접힘 된 후 염 놓도 구배에 의해 용출된다. 이 새로운 EBA-mediat$\xi$d 재접힘 방법은 응집현상을 획기적으로 줄이고 공정수율윤 향상시킬 뿐 아나라 공정단계 수를 줄일 수 있다. 이 공정은 우리가 알고 있는 한 세계에서 최초로 개발된 공정이며, 현재 single-chain polypeptide, affinity-tagged protein 등과 갈은 다른 행태의 단백질에 EBA를 사용한 재접힘 공정올 적용시키가 위한 연구가 진행되고 있다.

• 한국작물학회지
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• 제22권1호
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• pp.20-25
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• 1977

감자추작의 알맞는 재배법을 구명하기 위하여 1976년 천안에서 시마바라(도원)품종을 대상으로하여, 7월13일 4절종서를 GA$_2$ppm과 Ethrel 250ppm의 혼합액에 60분간 처리하여 노지의 최아상에 파종하고, 7월 24일 몇가지 재배처리를 하여 정식한 성적을 요약하면 다음과 같다. 1. 정식당시의 아장(아경)을 4cm(3.5mm), 7cm (4.5mm) 및 10cm(6.0mm)로 구분한즉 싹이 크고 굵은것이 발아 생육 수량 및 품질이 모두 증대향상 되었다. 2. 질소시용량을 10a당 요소 10, 20 및 30kg으로 구분한즉 질소시용량이 많을수록 생육 수량 및 품질이 모두 증대향상되었다. 3. 질소를 정식기(7월24일)에 전량기비로 주는 것 보다 정식기와 8월15일 또는 8월15일과 9월5일로 분시하는 것이 발아 생육 수량 및 품질이 모두 증대향상되었다. 4. 재식거리 60$\times$20cm 또는 70$\times$17cm이상의 밀식은 도장을 유발하여 수량 품질이 저하되었다. 5. 정식후에 밀짚을 4, 8, 12cm로 피복한즉 피복이 두꺼울수록 성하기의 최고지온을 낮추고 추냉기의 최저지온을 높이는 효과가 컸다.

• Current Applied Physics
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• 제18권11호
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• pp.1458-1464
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• 2018

An improved method for the preparation of g-$C_3N_4$ is described. Currently, heating (> $400^{\circ}C$) of urea is the common method used for preparing the g-$C_3N_4$. We have found that sonication of melamine in $HNO_3$ solution, followed by washing with anhydrous ethanol, not only reduce the crystallite size of g-$C_3N_4$ but also facilitate intriguing electronic structure and photoluminescence (PL) properties. Moreover, loading of metal (Pt and Ag) nanoparticles, by applying the borohydride reduction method, has resulted in multicolor-emission from g-$C_3N_4$. With the help of PL spectra and local electronic structure study, at C K-edge, N K-edge, Pt L-edge and Ag K-edge by X-ray absorption spectroscopy (XAS), a precise mechanism of tunable luminescence is established. The PL mechanism ascribes the amendments in the transitions, via defect and/or metal states assimilation, between the ${\pi}^*$ states of tris-triazine ring of g-$C_3N_4$ and lone pair states of nitride. It is evidenced that interaction between the C/N 2p and metal 4d/5d orbitals of Ag/Pt has manifested a net detraction in the ${\delta}^*{\rightarrow}LP$ transitions and enhancement in the ${\pi}^*{\rightarrow}LP$ and ${\pi}^*{\rightarrow}{\pi}$ transitions, leading to broad PL spectra from g-$C_3N_4$ organic semiconductor compound.

• 한국수산과학회지
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• 제55권6호
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• pp.875-885
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• 2022

This study was performed to confirm the optimal extraction method for antimicrobial peptides from the Hard-shelled mussel. Extractions were performed with two processes including 1% HAc/boiling and 1% HAc/non-boiling methods and used extracts for the comparison of the antimicrobial activity, protease stability, action mechanism, AU-PAGE (acid-urea PAGE), and HPLC chromatograms. 1% HAc/boiling extract showed potent antibacterial activities both against Gram-positive and negative bacterium but 1% HAc/non-boiling extract showed antibacterial activity only against Gram-positive bacteria. Treatment of 1% HAc/boiling extract with proteases retained almost antibacterial activity against B. subtilis, but abolished significant antibacterial activity against E. coli D31. Only 1% HAc/boiling extract showed two discrete clearing antibacterial zones including slow migrating and rapid migrating zones. Both extracts showed strong DNA-binding ability but did not show bacterial membrane permeabilizing ability. In comparison of the chromatogram obtained from C₁₈ or cation-exchange HPLC, the eluted peaks from 1% HAc/boiling extract showed high hydrophobic property or absorbance compared to 1% HAc/non-boiling extract, respectively. The concentration of the purified antimicrobial peptide was also higher in 1% HAc/boiling extract than in 1% HAc/non-boiling extract. Our results suggest that the effective extraction condition for antimicrobial peptides from marine invertebrate is boiling process in a weak acetic acid solution (1%).

• Journal of Chest Surgery
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• 제39권5호
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• pp.366-375
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• 2006

배경: 심폐바이패스를 이용한 심장수술에 따른 혈중 마그네슘 결핍 현상은 흔히 발생하는 합병중으로 이 연구의 목적은 심장수술시 인위적으로 첨가한 황산마그네슘의 유익한 임상 효과를 규명함에 있다. 대상 및 방법: 심폐바이패스를 이용하여 심장수술을 시행하기로 예정된 환자들 35명을 무작위로 황산마그네슘 투여군(n=15)과 투여하지 않은 군(n=20)으로 분류한 뒤 마그네슘군은 심폐기 충전액에 황산마그네슘 1g과 심정지액에 황산마그네슘 1g을 각각 첨가하였다. 요골 동맥으로부터 혈액을 채취하여 $Mg^{++}$ 농도, 전해질농도, 동맥혈액 가스분석, 혈액학적 분석, 혈청 총 단백 농도와 albumin 농도, blood urea nitrogen (BUN), creatinine, alanine amino transferase (ALT), aspartate aminotransferase (AST), total bilirubin 농도, tumor nerosis factor-${\alpha}$ $(TNF-{\alpha})$, interleukin-6 (IL-6), interleukin-10 (IL-10), creatine phosphokinase (CpK), creatine kinase-MB (CK-MB), lactate dehydrogenase (LDH), troponin-I (TNI) 농도, prothrombin time (PT)과 activated partial thromboplastin time (aPTT) 등도 측정하였다. 또한 수술 전과 후 정맥 혈액을 채취하여 activated clotting time (ACT)을 측정하였다. 결과: $Mg^{++}$ 농도는 수술 동안 및 후 시기에 마그네슘군이 대조군보다 유의하게 높게 유지되었다(p<0.05). 수술 전 부정맥이 없었던 환자들(대조군=10명, 마그네슘군=17명) 중 수술 후 부정맥 발생 수는 대조군이 10명(100%) 마그네슘군이 8명(46.4%)으로 마그네슘군이 대조군보다 유의하게 적었다(p=0.050). 결론: 심장수술 시 저용량의 황산마그네슘의 투여는 수술 중과 수술 후 저마그네슘 혈증의 예방과 부정맥의 빈도를 낮춰줄 것으로 생각한다.