• 대한환경공학회지
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• 제34권9호
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• pp.630-636
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• 2012

본 연구는 해양미세조류 Dunaliella salina을 LED 광원을 이용하여 배양한 연구로 배양에 필요한 최적의 파장, 광도, 공기공급속도 및 배양온도를 찾기 위하여 수행되었다. 낮은 배양온도에서보다는 높은 온도에서 성장이 빨랐으나, 본 실험에서는 $22^{\circ}C$에서 가장 잘 성장하는 것으로 확인되었다. LED 파장에 따른 성장실험에서는 백색 LED가 배양에 가장 효과적이었으며, 광도에 따른 실험에서는 실험 시 고려한 3가지 광도 중(3,000, 6,300, 8,000 Lux) 3,000 Lux에서 최대 세포농도인 1.30 g/L를 나타내었다. 공기공급속도의 증가는 Dunaliella salina의 성장속도와 반비례의 관계를 나타내었는데, 공기를 공급하지 않은 경우의 비증식속도 $1.12day^{-1}$와 비교하면 공기공급은 본 미세조류의 성장에 저해요인으로 작용함을 알 수 있었다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2009년도 제38회 동계학술대회 초록집
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• pp.480-480
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• 2010

In the present work, we studied effect of the deposition parameters on the structure and properties of ZnO films deposited by DC arc plasmatron. The varied parameters were gas flow rates, precursor composition, substrate temperature and post-deposition annealing temperature. Vapor of Zinc acetylacetone was used as source materials, oxygen was used as working gas and argon was used as the cathode protective gas and a transport gas for the vapor. The plasmatron power was varied in the range of 700-1,500 watts. Flow rate of the gases and substrate temperature rate were varied in the wide range to optimize the properties of the deposited coatings. After deposition films were annealed in the hydrogen atmosphere in the wide range of temperatures. Structure of coatings was investigated using XRD and SEM. Chemical composition was analyzed using x-ray photo-electron spectroscopy. Sheet conductivity was measured by 4-point probe method. Optical properties of the transparent ZnO-based coatings were studied by the spectroscopy. It was shown that deposition by a DC Arc plasmatron can be used for low-cost production of zinc oxide films with good optical and electrical properties. Sheet resistance of 4 Ohms cm was achieved after the deposition and 30 min annealing in the hydrogen at $350^{\circ}C$. Elevation of the substrate temperature during the deposition process up to $350^{\circ}C$ leads to decreasing of the film's resistance due to rearrangement of the crystalline structure.

• ALGAE
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• 제28권2호
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• pp.193-202
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• 2013

Nitrogen availability and cell density each affects growth and cellular astaxanthin content of Haematococcus pluvialis, but possible combined effects of these two factors on the content and productivity of astaxanthin, especially under outdoor culture conditions, is less understood. In this study, the effects of the initial biomass densities IBDs of 0.1, 0.5, 0.8, 1.5, 2.7, 3.5, and 5.0 g $L^{-1}$ DW and initial nitrogen concentrations of 0, 4.4, 8.8, and 17.6 mM nitrate on growth and cellular astaxanthin content of H. pluvialis Flotow K-0084 were investigated in outdoor glass column photobioreactors in a batch culture mode. A low IBD of 0.1 g $L^{-1}$ DW led to photo-bleaching of the culture within 1-2 days. When the IBD was 0.5 g $L^{-1}$ and above, the rate at which the increase in biomass density and the astaxanthin content on a per cell basis was higher at lower IBD. When the IBD was optimal (i.e., 0.8 g $L^{-1}$), the maximum astaxanthin content of 3.8% of DW was obtained in the absence of nitrogen, whereas the maximum astaxanthin productivity of 16.0 mg $L^{-1}\;d^{-1}$ was obtained in the same IBD culture containing 4.4 mM nitrogen. The strategies for achieving maximum Haematococcus biomass productivity and for maximum cellular astaxanthin content are discussed.

• Toxicological Research
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• 제28권4호
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• pp.241-248
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• 2012

Exposure of cells to ultraviolet B (UVB) radiation can induce production of free radicals and reactive oxygen species (ROS), which damage cellular components. In addition, these agents can stimulate the expression of matrix metalloproteinase (MMP) and decrease collagen synthesis in human skin cells. In this study, we examined the anti-photoaging effects of extracts of Tetraselmis suecica (W-TS). W-TS showed the strongest scavenging activity against 2,2-difenyl-1-picrylhydrazyl (DPPH) and peroxyl radicals, followed by superoxide anions from the xanthine/xanthine oxidase system. We observed that the levels of both intracellular ROS and lipid peroxidation significantly increased in UVB-irradiated human skin fibroblast cells. Furthermore, the activities of enzymatic antioxidants (e.g., superoxide dismutase) and the levels of non-enzymatic antioxidants (e.g., glutathione) significantly decreased in cells. However, W-TS pretreatment, at the maximum tested concentration, significantly decreased intracellular ROS and malondialdehyde (MDA) levels, and increased superoxide dismutase and glutathione levels in the cells. At this same concentration, W-TS did not show cytotoxicity. Type 1 procollagen and MMP-1 released were quantified using RT-PCR techniques. The results showed that W-TS protected type 1 procollagen against UVB-induced depletion in fibroblast cells in a dose-dependent manner via inhibition of UVB-induced MMP-1. Taken together, the results of the study suggest that W-TS effectively inhibits UVB-induced photoaging in skin fibroblasts by its strong anti-oxidant ability.

• 한국지하수토양환경학회지:지하수토양환경
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• 제21권1호
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• pp.86-93
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• 2016

Fenton is the reaction using the OH· radicals generating by interaction between hydrogen peroxide and Fe²⁺ which can oxidize the contaminants. Fe²⁺ ions are oxidized to Fe³⁺ ions by reaction with H₂O₂ and formed OH· radicals. UV-Fenton process includes the additional reaction that generates the OH· radicals by photodegradation of H₂O₂. In methylorange (MO) decolourization experiment with UV-Fenton, optimal Fe²⁺: H₂O₂ ratio was obtained at 1 : 10. Based on the obtained condition (H₂O₂= 10mM, Fe²⁺ = 1 mM) with/without UV-fenton experiment was carried out. Removal efficiency and sludge production were measured at 30 min. The case of w/o UV irradiation and only H₂O₂ was hardly treated and only Fe²⁺ showed 65% removal owing to coagulation. When UV-Fenton process in optimal ratio (Fe²⁺: H₂O₂ = 1 : 10), UV irradiation showed better removal efficiency than of w/o UV irradiation. Also, MO decolourization was a function of the hydrogen peroxide concentration (x₁), Fe²⁺:H₂O₂ ratio (x₂), and numbers of UV lamp (x₃) from the application of the response surface methodology. Statistical results showed the order of significance of the independent variables to be hydrogen peroxide concentration > numbers of UV l amp > Fe²⁺: H₂O₂ ratio.

• 한국해양바이오학회지
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• 제11권1호
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• pp.14-22
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• 2019

Omega-3 fatty acids and carotenoids, which are known as representative high-value substances derived from microalgae, are being studied from various diatoms. Most of the diatoms contain fucoxanthin and omega-3 fatty acid. Fucoxanthin produced by diatom has been reported as bioactive compounds exhibiting strong antioxidant, anticancer and anti-inflammatory activities. However, the low growth rate and fucoxanthin content of diatoms are one of the big obstacles to the industrial application. In this study, indigenous marine diatom Achnanthidium sp. BS-001 was isolated for a candidate of fucoxanthin producer. Light intensity and temperature for the culture of Achnanthidium sp. BS-001 were optimized on PhotoBiobox. Optimization of silicate concentration for increasing BS-001 biomass productivity was confirmed in F/2 medium with various concentration of sodium silicate. As a result, condition of light intensity, temperature, and silicate concentration for optimal cultivation were $150{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$, $18^{\circ}C$ and 0.106 mM, respectively. Maximum biomass productivity reaches to $154.3mg{\cdot}L^{-1}{\cdot}day^{-1}$, and then the content of omega-3 fatty acids and fucoxanthin were $19.4mg{\cdot}g^{-1}$, $9.05mg{\cdot}g^{-1}$, respectively. These results indicate that Achnanthidium sp. BS-001 has the potential to be used as a source of omega-3 fatty acids and fucoxanthin.

• 한국재료학회지
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• 제29권5호
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• pp.328-335
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• 2019

Nb-doped $TiO_2$(NTO) coated NiCrAl alloy foam for hydrogen production is prepared using ultrasonic spray pyrolysis deposition(USPD) method. To optimize the size and distribution of NTO particles based on good physical and chemical stability, we synthesize particles by adjusting the weight ratio of the Nb precursor solution(5 wt%, 10 wt% and 15 wt%). The morphological, chemical bonding, and structural properties of the NTO coated NiCrAl alloy foam are investigated by X-ray diffraction(XRD), X-ray photo-electron spectroscopy(XPS), and Field-Emission Scanning Electron Microscopy(FESEM). As a result, the samples of controlled Nb weight ratio exhibit a common diffraction pattern at ${\sim}25.3^{\circ}$, corresponding to the(101) plane, and have chemical bonding(O-Nb=O) at 534 eV. The NTO particles with the optimum weight ratio of N (10 wt%) show a uniform distribution with a size of ~18.2-21.0 nm. In addition, they exhibit the highest corrosion resistance even in the electrochemical stability estimation. As a result, the introduction of NTO coated NiCrAl alloy foam by USPD improves the chemical stability of the NiCrAl alloy foam by protecting the direct electrochemical reaction between the foam and the electrolyte. Thus, the optimized NTO coating can be proposed for excellent protection of NiCrAl alloy foam for hydrocarbon-based steam methane reforming(SMR).

• 대한심미치과학회지
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• 제27권2호
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• pp.105-115
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• 2018

치과기공사는 구강 모델에 기초하여 보철물을 제작하기 때문에 안모와의 부조화가 되는 경우가 있다. 안모와의 부조화에 기인한 보철물의 실패를 예방하기 위해서는 진료실과 기공소 간의 소통에 기반한 모델 진단, 안면 및 구강사진을 참고하여 제작해야한다. 그리고 치과기공사는 색과 형태에 대한 이해를 위해 자연치 관찰이 필요하며 Kuraray Noritake의 internal stain 및 투명감을 부여해 주는 powder를 이용하면 자연감 있는 보철물을 제작하데 용이하다.

• 한국의상디자인학회지
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• 제23권4호
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• pp.19-37
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• 2021

The purpose of this study is to apply the characteristics of David Hockney's paintings to fashion illustration and thereby, review how pure art can be harmoniously grafted onto fashion commodities and thereupon, suggest a far more developed and unique fashion illustration. For the research, this study analyzed David Hockney's late painting works, after the 1980s; the analysis was focused on photo collages, multiple perspectives, the movement of the viewpoint, and lights and colors. In order to produce an artwork, the researcher selected 4 painting works; one work for decade for the period from the 1980s to the 2010s. This study selected 'shoes' as subjects for expression in an effort to depart from the convention approach of focusing on apparel and thereby, suggest some differentiated fashion illustrations. In terms of the artwork production size, four canvases #5 were combined into a set, and thus, a total of four sets were developed. The results are as follows. First, it was very interesting to develop a fashion illustration making use of David Hockney's paintings, and it was proven that the fashion illustration applying the sensitivity of the pure art would provide a unique sense of art. Secondly, as the boundary among disciplines becomes blurred, painting provides a new source of insights and motifs to the diverse design areas to satisfy diversified human needs, and furthermore, the development and diversified application of the fashion illustrations could be confirmed. Thirdly, David Hockney's differentiated world of art, technique of expression and sensitive colors could well be applied to fashion illustrations. This study proves that we fashion artists can depart from the conventional expressions focused on the apparel to expand the fashion illustration into lady's high heels.

• 한국전기전자재료학회논문지
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• 제36권4호
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• pp.332-340
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• 2023

Crystalline silicon solar cells have attracted great attention for their various advantages, such as the availability of raw materials, high-efficiency potential, and well-established processing sequence. Tunnel oxide passivated contact (TOPCon) solar cells are widely regarded as one of the most prospective candidates for the next generation of high-performance solar cells because an efficiency of 26% has been achieved in small-area solar cells. Compared to n-type TOPCon solar cells, the photo conversion efficiency (PCE) of p-type TOPCon is slightly higher. The highest PCEs of p-type TOPCon and n-type TOPCon solar cells are 26.0% and 25.8%, respectively. Despite the highest efficiency in small-area cells, limited progress has been achieved in p-type TOPCon solar cells for large are due to their lower carrier lifetime and inferior surface passivation with the boron-doped c-Si wafer. Nevertheless, it is of great importance to promoting the p-type TOPCon technology due to its lower price and well-established manufacturing procedures with slight modifications in the PERC solar cells production lines. The progress in different approaches to increase the efficiencies of p-type TOPCon solar cells has been reported in this review article and is expected to set valuable strategies to promote the passivation technology of p-type TOPCon, which could further increase the efficiency of TOPCon solar cells.