• KSBB Journal
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• 제19권1호
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• pp.1-11
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• 2004

클로렐라는 생물화학적 성분들을 풍부하게 함유하고 있어서 영양학적으로 사료나 식품으로 이용되며 화장품, 의약품, 심지어 연료로도 이용되고 있다. 클로렐라는 보통 연못이나 호수 등 담수에서 생육하며, 구형 단세포이다. 생식은 무성생식으로 하루에 4-16배로 증식한다. 클로렐라의 대량생산을 위한 배양은 크게 옥외배양법과 발효조 배양법으로 나뉜다. 클로렐라는 필수 아미노산과 생체에 여러 가지 생리적 기능을 수행하는 지방산과 스테롤, 유산균 성장 촉진 원인 물질인 chlorella growth factor (CGF)의 함유되어 있으며, 생체 내에서 중금속 배출기능, 독성물질의 분해, 동맥경화 및 간장장애의 억제, 면역기능 강화, 항암 활성, 장내 유효세균의 증식 촉진, 식품의 풍미 향상 및 보습효과 등의 기능성을 가지고 있어 기능성 생물소재로 주목되고 있다. 클로렐라는 건강기능식품, 화장품, 의약품 소재로서 응용될 수 있을 뿐만 아니라 이산화탄소의 고정화와 수소가스의 생성 등 환경 및 에너지의 생산을 위한 수단으로서의 역할이 전망된다.

• 한국가스학회지
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• 제23권6호
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• pp.33-38
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• 2019

제조식 수소충전소에서 생산되는 수소가스는 일반적으로 석탄연료의 개질 및 부생가스 등을 활용하지만 순수물을 활용한 수전해 기술의 경우 청정한 기술로 각광 받고 있다. 전기에너지를 이용하여 순수한 물로부터 수소를 생산하는 기술 중에는 향후 가격 및 성능 경쟁에서 우수한 PEM(Polymer Electrolyte Membrane electrolysis)을 이용한 개발이 주로 이루어지고 있다. 이에 본 연구에서는 국내 수소충전소 중 개발단계에 있는 PEM 수전해 수소충전소에 대해 잠재된 유해위험요소를 확인하여 안전한 수소생산 및 수소충전소의 활성화를 도모하고자 한다. 유해위험요소를 도출하기 위해서는 수전해 수소충전소의 설비 및 장치의 안전성이 우선 확보되어야하기에 FMEA(Failure Mode & Effect Analysis)를 수행함으로써 수전해 및 수소충전소의 설비에서의 유해위험요인을 분석하였다.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 1999년도 추계 학술대회논문집
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• pp.127-138
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• 1999

본 연구에서는 2 차원 캐비티 유동에서 경계조건 부여 방법의 차이에 따른 유체유동의 이력이 최종적인 정상상태에 미치는 효과를 수치실험을 통하여 관찰하였다. 그 결과 유동의 Reynolds 수가 작은 경우는 유동장이 가지는 이력이 시간의 경과와 함께 소멸하여 하나의 정상유동 상태를 가지는데 반하여, 큰 Reynolds 수에서는 유동장 이력이 소멸하지 않고 유지됨으로 인하여 다수의 정상유동 형태가 나타남이 확인이 되었다. 엄밀한 이론적 해석은 현재 이루워지지 않았으나 유체 운동량의 증가에 따라 Navier-Stokes 방정식의 비선형성이 영향을 미치고 있다고 여겨진다.

• 한국응용과학기술학회지
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• 제30권1호
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• pp.88-95
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• 2013

본 연구는 1차 아민(MEA, monoethanolamine)으로 개질한 입자상 활성탄(WSC-470)을 이용하여 실내 저농도 이산화탄소를 제거하고자 하였다. MEA 함침농도(6.1~42.7 wt.%)와 용매제(distillate water, ethanol, methanol) 종류에 따라 제조된 흡착제의 특성분석(BET, pore property, XPS)과 각 흡착제의 $CO_2$가스에 대한 최대 흡착능, 3000 ppm의 저농도 $CO_2$분위기에서의 흡착량을 측정하였다. MEA 농도가 증가할수록 물리적 특성인 비표면적, 공극률, 미세기공률 등은 감소한 반면, 표면 염기도 향상에 기여하는 질소 함량은 증가하였다. 이러한 물성변화로 인해 최대 흡착능은 초기 활성탄(RAC: 3.27 mmol/g) 대비 최대 71%(AC-MM(42.7, 40): 0.937 mmol/g)가 감소한 반면, 저농도 이산화탄소에 대한 선택적 흡착량은 45%(AC-MM(15.3, 40): 0.73 mmol/g)의 향상을 보였다.

• BMB Reports
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• 제41권10호
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• pp.699-704
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• 2008

Embryonic stem (ES) cell-derived cardiomyocytes (ESCMs) must be specifically purified in order to prevent teratoma formation, and this confusing issue has hampered their clinical application. We therefore investigated a technique to generate pure labeled ESCMs for possible use in cardiac repair. We generated transgenic ES cell lines expressing enhanced green fluorescent protein (EGFP) under the transcriptional control of the $\alpha$-cardiac myosin heavy chain ($\alpha$-MHC) promoter. Differentiated EGFP-positive ES cells displayed characteristics of CMs. Furthermore, neuregulin-1 (NRG-1) upregulated the expression of the cardiac-restricted transcription factors Nkx2.5 and GATA-4, as well as differentiated CM factors ($\alpha$-MHC, $\beta$-MHC). Immunohistochemistry demonstrated that NRG-1 increased expression of cardiac-specific troponin T in the beating foci of the embryoid bodies. This work revealed a potential method for specifically labeling and enriching ESCMs by combining genetically-engineered ES cell clones and exogenous growth factor treatment.

• 한국재료학회지
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• 제11권4호
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• pp.251-257
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• 2001

반도체 소자의 고집적화에 따른 세정공정 수는 점점 증가하고 있는 추세에 있다 현재 사용되는 세정은 다량의 화학약품 및 초순수를 소비하며, 고온에서 행하여지고 있는 RCA세정을 근간으로 하고 있다. 세정공정수의 증가는 바로 화학약품의 사용량 증가를 초래하게 되며, 이에 따른 환경문제가 심각하게 대두되고 있는 실정에 이르렀다. 따라서 이러한 화학약품 및 초순수 사용을 절감하고, 저온에서 세정공정이 이뤄지는 기술이 향후 요구되어 지고 있다. 이번 연구는 이러한 관점에서 화학약품 및 초순수 사용량을 줄이며, 상온 공정이 이뤄지는 전리수를 이용하여 실리콘 웨이퍼 세정을 하였다. 제조된 전리수는 산화성 성질을 지닌 양극수와 환원성 성질인 음극수로 이루어지고, 각각 pH 및 ORP는 4.7/+1050mV, 9.8/-750mV를 30분 이상 유지하고 있었다 전리수의 양극수에 의한 금속제거 효과가 음극수의 효과보다 우수함을 확인할 수 있었으며, 다양한 입자제거 실험에도 불구하고, 동일한 분포도를 나타내고 있었다.

• 한국재료학회지
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• 제12권12호
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• pp.941-946
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• 2002

Both Cu and Cu-oxide nanopowders have great potential as conductive paste, solid lubricant, effective catalysts and super conducting materials because of their unique properties compared with those of commercial micro-sized ones. In this study, Cu and Cu-oxide nanopowders were prepared by Pulsed Wire Evaporation (PWE) method which has been very useful for producing nanometer-sized metal, alloy and ceramic powders. In this process, the metal wire is explosively converted into ultrafine particles under high electric pulse current (between $10^4$ and $10^{ 6}$ $A/mm^2$) within a micro second time. To prevent full oxidations of Cu powder, the surface of powder has been slightly passivated with thin CuO layer. X-ray diffraction analysis has shown that pure Cu nanopowders were obtained at $N_2$ atmosphere. As the oxygen partial pressure increased in $N_2$ atmosphere, the gradual phase transformation occurred from Cu to $Cu_2$O and finally CuO nanopowders. The spherical Cu nanopowders had a uniform size distribution of about 100nm in diameter. The Cu-oxide nanopowders were less than 70nm with sphere-like shape and their mean particle size was 54nm. Smaller size of Cu-oxide nanopowders compared with that of the Cu nanopowders results from the secondary explosion of Cu nanopowders at oxygen atmosphere. Thin passivated oxygen layer on the Cu surface has been proved by XPS and HRPD.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2017년도 춘계학술대회 논문집
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• pp.149-149
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• 2017

Aluminum alloys have poor corrosion resistance compared to the pure aluminum due to the additive elements. Thus, anodizing technology artificially generating thick oxide films are widely applied nowadays in order to improve corrosion resistance. Anodizing is one of the surface modification techniques, which is commercially applicable to a large surface at a low price. However, most studies up to now have focused on its commercialization with hardly any research on the assessment and improvement of the physical characteristics of the anodized films. Therefore, this study aims to select the optimum temperature of sulfuric electrolyte to perform excellent corrosion resistance in the harsh marine environment through electrochemical experiment in the seawater upon generating porous films by variating the temperatures of sulfuric electrolyte. To fabricate uniform porous film of 5083 aluminum alloy, we conducted electro-polishing under the 25 V at $5^{\circ}C$ condition for three minutes using mixed solution of ethanol (95 %) and perchloric (70 %) acid with volume ratio of 4:1. Afterward, the first step surface modification was performed using sulfuric acid as an electrolyte where the electrolyte concentration was maintained at 10 vol.% by using a jacketed beaker. For anode, 5083 aluminum alloy with thickness of 5 mm and size of $2cm{\times}2cm$ was used, while platinum electrode was used for cathode. The distance between the two was maintained at 3 cm. Anodic polarization test was performed at scan rate of 2 mV/s up to +3.0 V vs open circuit potential in natural seawater. Surface morphology was compared using 3D analysis microscope to observe the damage behavior. As a result, the case of surface modification showed a significantly lower corrosion current density than that without modification, indicating excellent corrosion resistance.

• Journal of Pharmaceutical Investigation
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• 제17권3호
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• pp.111-126
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• 1987

Methyl methacrylate-butyl methacrylate copolymer (MMBM)-dibutyl phthalate (DBP) films were investigated as a potential topical drug delivery system for the controlled release of nitrofurazone. The kinetic analysis of release data indicated that drug release followed a diffusion-controlled granular matrix model, where the quantity released per unit area is proportional to the square root of time. DBP of several hydrophobic plasticizers selected was found to give the highest release of nitrofurazone. However, hydrophilic plasticizers such as propylene glycol and polyethylene glycol 400 had no controlled release properties and acceptable film formation. The effects of changes in film composition, drug concentration, film thickness, pH of release medium, and temperature on the in vitro release of nitrofurazone were analyzed both theoretically and experimentally. The release rate constant (k') was found to be proportional to DBP content, pH, and the temperature of release medium, but independent of film thickness, and drug concentration in a range of 0.1-0.4% by weight. The linear relationship was found to exist between the log k' and DBP content. The release of nitrofurazone from MMBM-DBP (8:2) films was found to be an energy-linked process. Two energy terms were calculated ; the activation energy for matrix diffusion was 13.45 kcal/mole, and the heat of drug crystal solvation was 27.26-29.34 kcal/mole. Observation of scanning electron micrographs and microscopic photographs showed that the incorporation of DBP in films increased markedly the particle size of nitrofurazone dispersed in the film matrix, comparing with the fine dispersion of nitrofurazone in pure MMBM film alone.

• Journal of Microbiology and Biotechnology
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• 제19권11호
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• pp.1439-1446
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• 2009

Isocarbophos is a widely used organophosphorus insecticide that has caused environmental pollution in many areas. However, degradation of isocarbophos by pure cultures has not been extensively studied, and the degradation pathway has not been determined. In this paper, a highly effective isocarbophos-degrading strain, scl-2, was isolated from isocarbophos-polluted soil. The strain scl-2 was preliminarily identified as Arthrobacter sp. based on its morphological, physiological, and biochemical properties, as well as 16S rDNA analysis. The strain scl-2 could utilize isocarbophos as its sole source of carbon and phosphorus for growth. One hundred mg/l isocarbophos could be degraded to a non detectable level in 18 h by scl-2 in cell culture, and isofenphos-methyl, profenofos, and phosmet could also be degraded. During the degradation of isocarbophos, the metabolites isopropyl salicylate, salicylate, and gentisate were detected and identified based on MS/MS analysis and their retention times in HPLC. Transformation of gentisate to pyruvate and fumarate via maleylpyruvate and fumarylpyruvate was detected by assaying for the activities of gentisate 1,2-dioxygenase (GDO) and maleylpyruvate isomerase. Therefore, we have identified the degradation pathway of isocarbophos in Arthrobacter sp. scl-2 for the first time. This study highlights an important potential use of the strain scl-2 for the cleanup of environmental contamination by isocarbophos and presents a mechanism of isocarbophos metabolism.