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Luminescence of $Eu^{3+}$ and $Sm^{3+}$ Doped Potassium Tungstate Phosphor

  • Lee, Gwan-Hyoung;Kim, Tae-Hyung;Kang, Shin-Hoo
    • Journal of Information Display
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    • v.6 no.2
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    • pp.25-29
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    • 2005
  • The luminescent properties of $Eu^{3+}$ and $Sm^{3+}$ doped potassium tungstate phosphor are investigated. The $K_{4-3x}(WO_4)_2:Eu^{3+}\;_x,Sm^{3+}\;_y$ phosphor is produced by firing the mixed precursors, followed by re-firing with a flux. The re-firing process results in the defect-free surface and uniform growth of the particles. The strong absorption in the region of ultra violet light is observed due to the 4f-4f electron transitions of the $Eu^{3+}$ and $Sm^{3+}$ ions. The doping concentration of europium into potassium tungstate is relatively high, compared to other host materials. It is revealed that the crystal structure is a monoclinic with space group, C2/c. This crystal structure facilitated the $Eu^{3+}$ ions to be located with the Eu-Eu distance larger than 5 ${\AA}$ so that concentration quenching does not occur even at high doping concentration. The excitation spectrum could be adjusted by the introduction of the samarium. A small amount of the $Sm^{3+}$ ions that acts as a sensitizer increases the energy absorption peak around 405 nm.

n-type ZnO 위 수직 성장된 p-type ZnO 나노와이어 구조의 동종접합 다이오드

  • Hwang, Seong-Hwan;Lee, Sang-Hun;Mun, Gyeong-Ju;Lee, Tae-Il;Myeong, Jae-Min
    • Proceedings of the Materials Research Society of Korea Conference
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    • 2012.05a
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    • pp.87.1-87.1
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    • 2012
  • 넓은 밴드갭 (3.37eV)과 높은 엑시톤 결합에너지 (60meV)를 가지는 ZnO 물질은 ultra violet light 센서 및 light emitting diode (LED)의 재료로써 많은 연구가 진행되고 있다. 특히 나노와이어 구조를 이용하여 소자를 만들 경우 양자효과와 1차원적 캐리어 수송경로 효과로 인하여 그 특성을 보다 향상 시킬 수 있다. 나노와이어를 이용한 이종접합 p-n 다이오드를 제작하기 위하여 ZnO와 격자상수가 비슷한 GaN, NiO, CoO와 같은 물질들이 나노구조 접합에 많이 쓰이고 있지만, 격자상수 차이로 인해서 접합부분 캐리어 수송효율이 떨어지는 단점을 가지고 있다. n-type과 p-type ZnO를 만들어 동종 접합을 만들 경우 이러한 문제점을 극복할 수 있지만, 도핑되지 않은 ZnO가 n-type을 특성을 나타내기 때문에 안정적인 p-type ZnO 합성에 대한 연구가 필수적이다. 본 연구에서는 안정적인 p-type ZnO 합성을 위해서 수열합성법을 이용하여 phosphorus (P) 도핑을 하였고, 나노와이어 diode 구조를 만들었다. P 도핑으로 인한 격자상수 변화는 x-ray diffraction (XRD)를 사용하여 확인하였고, x-ray photoelectron spectroscopy (XPS)를 통해 도핑 원소를 분석하였으며, 이때의 recification ratio, turn-on voltage 등의 전기적 특성을 평가하였다.

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Characterization of nano-structure pyrolytic char for smart and sustainable nanomaterials

  • N. K. Karthikeyan;S. Elavenil
    • Advances in nano research
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    • v.16 no.1
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    • pp.53-69
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    • 2024
  • Advancements in the technology of building materials has led to diverse applications of nanomaterials with the aim to monitor concrete structures. While there are myriad instances of the use of nanoparticles in building materials, the production of smart nano cement-composites is often expensive. Thereupon, this research aims to discover a sustainable nanomaterial from tyre waste using the pyrolysis process as part of the green manufacturing circle. Here, Nano Structure Tyre-Char (NSTC) is introduced as a zero-dimension carbon-based nanoparticle. The NSTC particles were characterized using various standard characterization techniques. Several salient results for the NSTC particles were obtained using microscopic and spectroscopic techniques. The size of the particles as well as that of the agglomerates were reduced significantly using the milling process and the results were validated through a scanning electron microscope. The crystallite size and crystallinity were found to be ~35nm and 10.42%, respectively. The direct bandgap value of 5.93eV and good optical conductivity at 786 nm were obtained from the ultra violet visible spectroscopy measurements. The thermal analysis reveals the presence of a substantial amount of carbon, the rate of maximum weight loss, and the two stages of phase transformation. The FT-Raman confirms the presence of carboxyl groups and a ID/IG ratio of 0.83. Water contact angle around 140° on the surface implies the highly hydrophobic nature of the material and its low surface energy. This characteristic process assists to obtain a sustainable nanomaterial from waste tyres, contributing to the development of a smart building material.

Complementary Color Scheme Which Appeared in Women's Fashion Collections of New York, Milan, Paris, and London

  • Kwon, Hae-Sook
    • Journal of Fashion Business
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    • v.13 no.6
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    • pp.125-136
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    • 2009
  • The main objective of this research was to understand the characteristics of complementary color scheme through the analysis of contemporary women's fashion color coordination as they appear in the 'Collections'. Data collection of 115 was done through review of 'pr$\hat{e}$t-$\grave{a}$-porter Collections' of four cities; Milan, London, New York, Paris. Statistical analysis of frequency and also qualitative interpretation of characteristics of complementary color harmony characteristics which appeared in four collections were completed. The main findings were as followed; (1) Only 115 complementary color schemes out of 4968 two color combinations appeared. Compared the comparative ratios of appearance frequency between the two color combination and the complementary color harmony, London showed the highest, and followed by New York, and Milan and Paris. (2)The combined color type of 'red+green' was the most frequently appeared, and followed by 'violet+yellow' and 'orange+blue'. For the type of tone harmony, the contrast tone showed the most, and followed by the similarity and identity. According to the type of complementary color combination, the type of tone harmony used differently. Some differences showed in the types of color harmony and tone harmony between collections. (3) The complementary color scheme which shown in four collections harmonized two opposite colors mainly through the strong tone contrast and this could cause tension along with interest in the image. The complementary colors intensified and brought out the attributes each other. More details, high contrast of two complementary colors of yellow and violet created a vibrant look especially when used at higher saturation. Sometimes, however, some tone variations of two hues neutralized the strong effect and sometimes enhanced each other. When they used in similarity tones or identity tones in light colors, the tension was reduced and became softened but still presented nice harmony. In the type of 'red+green' color harmony, the various color combinations were demonstrated, mostly through tone manipulation of green color. The similarity tone harmony, which used the most, could effect a better sense of harmony and present more sophisticated looks. When used in contrast tone harmony, some changes in its own color which have only one color of two the excessive intensity led a good harmony. The 'orange+blue' color harmony was shown the least and used three tone harmony almost the same ratio. In this color harmony, blue amplified its energy and brilliance of orange and seemed to work better when one color was at a lower intensity than the other. In harmony with a similarity and an identity tone, this color harmony produces a stable and calm image. (4) The complementary scheme appeared more frequently in the S/S collections than in A/W collections and showed some differences in the types of color harmony and tone harmony between seasons, however, no big differences between collections.

Gastroepiploic Artery Preservation with Glycerol as a Training Model for Microvascular Anastomosis (미세혈관문합술의 연습 모델로서 글리세롤 처리된 위대망동맥의 활용)

  • Park, Chan Young;Chang, Hak;Chung, Jin Haeng;Heo, Eun Ju;Minn, Kyung Won;Yoo, Moon Won;Yang, Han Kwang
    • Archives of Plastic Surgery
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    • v.35 no.5
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    • pp.626-629
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    • 2008
  • Purpose: We investigate the possibility of vessel preservation with glycerol and evaluate the potential of preserved gastroepiploic artery as a tool for the microsurgical practice. Methods: In 5 early gastric cancer patients, IRB(No. C-0603-040-170), we gained gastroepiploic artery specimens(5 segments, about 10 cm) after gastrectomy. Each segment was rinsed in a normal saline and subsequently placed in a bottle, containing 50 mL anhydrous glycerol (87%). The bottles were refrigerated at $4^{\circ}C$, the longest preservation time being 5 months. Results: At first glance, no fragmentation was detected and the surface of vessel seemed mild sclerotic. In histological examination, vascular structures remained intact though preservation with glycerol led to a mild atrophy of the smooth muscle in the tunica media. Especially, we found out the elastic fibers and endothelial lining of the intima were preserved until 5 months. Adequate status for using microsurgical practice was also maintained and leakage test was performed successfully with gentian violet ink. Conclusion: Based on the results obtained in this study, the gastroepiploic artery preservation with glycerol as a training model for microvascular anastomosis is a technically very simple procedure and useful for the novice microsurgeon.

A study of Symbolics of Chinese Liturgical Vestments (중국 제복의 상징성에 관한 연구)

  • 이선희
    • Journal of the Korean Society of Costume
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    • v.18
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    • pp.111-131
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    • 1992
  • This thesis was designed to study Symbolics of Chinese Liturgical Vestments. Chinese who regarded the life of human beings as the combination of heaven and earth considered garments as the traditional product of the movement of nature. Accordingly, they thought human beings are the center of the universe composed by heaven and earth and the chief of all things; therefore man only can utilize clothes to distinguish from all of the colours. This views of clothes led to the development of liturgical vestments esteemed courtesy than anything else, especially the thought of courtesy associated with Conficius who regarded courtesy as the highest things and since then the theory of Five Elements and courtesy were inherited by all the adherents of Conficius. Yin and Yang Five Elements in the liturgical vestments was given absolute symbolics in both formative side and in colourful side. results of research studied in this was can be summed up as follows : 1. The crown of rites was made imitating after the system of head, horn, beard, bread of birds and beasts and that form of crown is front-circ-ular and back-rectangular meant to be towards light and dark. That the upper part of faceplace is black represented the way of heaven and lower part of red symbolized the way of earth. 2. Upper vestment of liturgical rites symbolizes heaven and outskirt represented earth. So front of outskirt is YANG and back is Yin. It is why then are going to harmonize positive and negative making front part three width and back part four width. Therefore, emperor who symbolizes heaven made the subjects recognize high and low and wore Dae-gu(大 ), Kon-bok(袞服), Bel-bok, Chui-bok, and Hyonbok according to the object and position of rites so that he may rule the country based on courtesy. 3. As an accessory of liturgical vestments, Bul, Pae-ok, Su, Dae-dai, Hyok-Dai, Kyu, and Hol were used. Before Bul was used man dressed skirt as the first waist-dress in order to conceal intimate part of the body. Pae-ok, as decoration blended with jade was worn by men of virtue, so men of virtue symbolized morality and virtue by Pae-ok. Su began from Yeok, connected with Pae-su , in Chou-dynasty is said to be originated by practical needs and they are divided into large Su and small su, and maintained as decoration to signify the class positions. Dae-dai did the work as not to loose the liturgical vestments and leather belt hang Bul and Su to begin as the function of practical use are in later years it became decoration to symboliz e the class position. Kyu was a jade used when empeor nominated feudal lords and observe ceremony to God and Hol, was held in hands to record everything not to forget. These Kyu and Hol became to offer courtesy during the time of rites and in later years it became used according to class position rather than practical use. 4. As far as colours are concerned, colours based by five colours according to YIN-YANG Five Elements theory and they were divided into a primary colour and a secondary colours. Primary colours corresponded with the theory of Five Elements each other, Blue, Red, Tellow, White, and Black symbolized ive Elements, five hour space, five directions, and five emperors. Secondary colours contradict with Blue, Red, Yellow, White and Black and another as a primary colour and they are Green, Scaret, Indigo, Violet, Hun colour, Chu colour, and Chi colour. This primary colour was used in liturgical vestments, that is, upper-vestments used black colour. This primary colour was used in liturgical vestments, that is, upper-vestments used black colour as primary colour and outskirt was used Hun colour as secondary colours. Thus symbolism in chinese liturgical vestments mainly began with heaven and earth and corresponded with YIN-YANG Five Elements Scool. They were developed as the scholary theory and Conficius and his followers in the later days and continued up to Min-dynasty.

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The Effect of Photomodulation in Human Dermal Fibroblasts (피부 섬유아세포에서 광자극의 효과)

  • Kim, Mi Na;Kwak, Taek Jong;Kang, Nae Gyu;Lee, Sang Hwa;Park, Sun Gyoo;Lee, Cheon Koo
    • Journal of the Society of Cosmetic Scientists of Korea
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    • v.41 no.4
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    • pp.325-331
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    • 2015
  • Skin is exposed to sunlight or artificial indoor light on a daily. The reached solar light on the earth surface consist of 50% visible light and 45% infrared (IR) except for ultra violet (UV). The negative effects of UV including UVB and UVA have been steadily investigated within the last decades. However, little is known about the effects of visible or IR light. In this study, we irradiated human dermal fibroblasts using light emitting diode (LED) to investigate the optimal parameter for enhancing cell growth and collagen synthesis. We found that red of 630 nm and green of 520 nm enhance the cell proliferation, but irradiation with purple and blue light exerts toxic effects. To examine the response of irradiation time and light intensity on the fibroblasts, cells were exposed to red or green light with intensities from 0.05 to $0.75mW/cm^2$. Procollagen secretion was increased of 1.4 fold by 10 min irradiation, while 30 min treatment decreased the collagen synthesis of dermal fibroblasts. Treatment with red of $0.3mW/cm^2$ and green of 0.15 and $0.3mW/cm^2$ resulted in enhancement of collagen mRNA. Lastly, we investigated the combinatorial effect of red and green light on dermal fibroblasts. The sequential irradiation of red and green light is an efficient way for the purpose of the increase in the number of fibroblasts than single light treatment. On the other hand, the exposure of red light alone was more effective method for enhancing of collagen secretion. Our study showed that specific light parameters accelerated cell proliferation, gene expression and collagen secretion on human dermal fibroblasts. In conclusion, we demonstrate that light exposure with specific parameter has beneficial effects on the function of dermal fibroblasts, and suggests the possibility of its cosmetically and clinical application.