2,319 research outputs found
광자결정 광섬유 음향광학 필터 특성에 관한 연구
No full text학위논문(박사) - 한국과학기술원 : 물리학과, 2009.2 , [ iv, 87 p. ]This thesis is concerned with all-fiber acousto-optic tunable filters (AOTFs) using a solid-core two-mode (TM) photonic crystal fiber (PCF).
Firstly, the origin of multiple resonance peaks observed in an all-fiber acousto-optic tunable filter built with a TM PCF having structural imperfections is investigated in detail. Small disorder in the six-inner air holes around the core can break the mode symmetry of the PCF. For this reason, first higher-order modes of the PCF are classified into the even and the odd LP11 modes resembling those of an elliptical-core (e-core) two-mode fiber (TMF). The PCF has also non-circularity in outer cladding shape, which causes to the acoustic birefringence of the fiber. A model for the acousto-optic mode coupling in the PCF is formulated for the systematic analysis on the origin of the distorted spectral peaks. Numerical calculations and simulations based on the coupling model were performed, and the results are in good agreement with the experimental observations.
Nextly, the resonance peak splitting in the output spectrum of a TM PCF-based AOTF under the fiber twist of up to multiple turns is described. The PCF guides the even and the odd -like modes in the core as a first higher-order mode. For the twist rate of our interest, lobe orientations of the -like modes follow the fiber twist, whereas the initial acoustic vibration direction is maintained along the fiber. Accordingly, the acoustic amplitude contributing to the mode coupling of the mode to the modes is sinusoidally modulated along the fiber. This is substantially the same to amplitude beating between two acoustic waves with difference propagation constant. Therefore, the fiber twist leads to the two phase-matching conditions that result in two notches in the transmission spectrum. Theoretical calculations based on the coupled-mode theory provide an accurate explanation of the resonance peak splitting. The peak separation is ...한국과학기술원 : 물리학과
Study on the characteristics of granular high-Tc superconducting film and the effect on the superconducting magnet
No full text학위논문(박사) - 한국과학기술원 : 물리학과, 2006.8, [ viii, 131 p. ]고온초전도 선재 제작에 있어 완충층은 금속기판이 초전도층 증착시 금속이 Diffusion 하는 것을 막아주기 위하여 증착한다. 이러한 대표적인 물질은 YSZ인데, 이는 금속 기판 위에 곧바로 수직성장하기 어려우므로 나 를 증착한다. 이것은 금속기판 Ni과 격자상수를 맞추기 위한 것으로 무엇보다 결정성이 좋아야 하고, 표면이 매끄러워야 한다. 증착 결과 는 표면이 매끄럽고, 는 결정성이 좋다. 는 의 기판 온도와 물분압 에서 수직성장하고, 는 에 비해 넓은 범위에서 쉽게 증착되어 의 이상의 기판 온도와 물분압 에서 수직성장을 한다. 나 위에 YSZ를 물을 넣어주면서 DC reactive sputtering을 통해 증착한다. 마지막 완충층은 결정성이 좋은 를 증착하여 결정성을 좋게 하고, 격자상수를 맞추어준다. 그리고 초전도층 SmBCO, DyBCO, SmDyBCO 등을 thermal evaporation으로 증착한다. SmBCO의 결정성, 표면, 임계온도, 임계전류 등의 특성은 증착 온도, 산소분압, 증착률, 증착 후 산소처리 등과 밀접한 관계가 있다. 여기서는 산소 분압 1~6mTorr의 범위와 기판 온도 640~ 의 범위에서 증착하였다. 산소 분압이 5mTorr일 때 결정성이 가장 좋고, 온도가 낮을 때는 a축 성장을 하고, 온도가 높으면 (103) 성장을 한다. 그리고 산소 분압이 높고, 온도가 높을수록 표면에 생성되는 BaCuO 상들의 크기가 증가한다. 이러한 초전도층을 STO bicrystal에 증착하여 자기장의 크기와 방향에 따른 I-V curve의 Hysteresis를 분석해 보았다. Bicrystal은 하나의 Grain Boundary(Josephson junction)를 제공하여 임계전류밀도( )의 감소를 유발한다. 이 때의 는 Josephson vortex의 운동에 의해 결정된다. 자기장의 방향을 바꾸어 주면서 의 Hysteresis 현상을 얻었고, 이를 수평성분과 수직성분으로 나누어 이해해 보았다. 수평성분은 Bean 모델을 따르고, 수직성분은 Brandt 이론을 따르는 것으로 이해하고, 임의의 각에서는 두 성분을 곱하는 것으로 이해해 보았다. 초전도층을 가해지는 액체질소나 수증기로부터 보호하고, eddy current를 형성시켜서 초전도체의 vortex motion을 막아주어 quenching으로부터 보호하기 위해 안정화층으로서 은이나 구리를 증착하여 실제 응용에 사용한다. 이러한 Coated Conductor(CC)가 실제로 응용될 수 있는 자석에 대하여 계산하여 보았다. CC의 이방성을 고려하였을 때 자기장의 분포와 그로 인한 임계전류 변화를 고려하여 FEMM4.0 프로그램을 사용하여 가 self-consistency를 만족하도록 계산하였다. 에 대해 6가지 model을 세우고 그에 따른 자기장 분포를 계산해 보았다. Intrinsic pinning만 존재할 경우 자석 중심에서 형성되는 자기장은 6.14T이고, columnar pinning의 크기가 intrinsic pinning의 1/4이었을 때는 7.58T 이다. 즉 columnar pinning의 성분이 중요하게 작용함을 알 수 있다. 인위적으로 columnar pinning을 제작하기 위해서는 무거운 이온을 irradiation 하거나 nano-material을 patterning하여야 하는데, 이를 자석이 양단의 온도를 낮춤으로서 columnar pinning의 효과를 갖도록 하여 계산해 보았다. 가장자리의 온도와 중심부분의 온도 차가 25K 정도 일 때가 자기장이 효율적으로 증가한다.한국과학기술원 : 물리학과
Fabrication BaO buffer layer on the Ni substrates and properties of the superconductng SmBCO grain boundary
No full text학위논문(석사) - 한국과학기술원 : 물리학과, 2002.2, [ [ii], 41 p. ]한국과학기술원 : 물리학과
Metabolic pathway of 3,6-anhydro-D-galactose in carrageenan-degrading microorganisms
No full textComplete hydrolysis of kappa-carrageenan produces two sugars, D-galactose and 3,6-anhydro-D-galactose (D-AnG). At present, however, we do not know how carrageenan-degrading microorganisms metabolize D-AnG. In this study, we investigated the metabolic pathway of D-AnG degradation by comparative genomic analysis of Cellulophaga lytica LIM-21, Pseudoalteromonas atlantica T6c, and Epulopiscium sp. N.t. morphotype B, which represent the classes Flavobacteria, Gammaproteobacteria, and Clostridia, respectively. In this bioinformatic analysis, we found candidate common genes that were believed to be involved in D-AnG metabolism. We then experimentally confirmed the enzymatic function of each gene product in the D-AnG cluster. In all three microorganisms, D-AnG metabolizing genes were clustered and organized in operon-like arrangements, which we named as the dan operon (3,6-d-anhydro-galactose). Combining bioinformatic analysis and experimental data, we showed that D-AnG is metabolized to pyruvate and D-glyceraldehyde-3-phosphate via four enzyme-catalyzed reactions in the following route: 3,6-anhydro-D-galactose -> 3,6-anhydro-D-galactonate -> 2-keto-3-deoxy-D-galactonate (D-KDGal) -> 2-keto-3-deoxy-6-phospho-D-galactonate -> pyruvate + D-glyceraldehyde-3-phosphate. The pathway of D-AnG degradation is composed of two parts: transformation of D-AnG to D-KDGal using two D-AnG specific enzymes and breakdown of D-KDGal to two glycolysis intermediates using two DeLey-Doudoroff pathway enzymes. To our knowledge, this is the first report on the metabolic pathway of D-AnG degradation.11Nsciescopu
Types of brand transgressions and consumers' moral reasoning strategies on an endorser
No full textThis study aims to examine the effects of types of brand transgressions and moral reasoning strategies (moral decoupling and moral rationalization) on consumers' trustworthiness in and attitudes toward an athlete endorser when a brand company that sponsors the athlete commits transgressions. By using a professional research company, 440 individuals were recruited online. The one-way analysis of variance (ANOVA) results reveal that consumers' trustworthiness of and attitudes toward the endorser are likely to be lower for product transgressions than for moral transgressions. Higher levels of moral decoupling show significantly higher trustworthiness of and attitudes toward the endorser than the middle and lower levels do. To keep an endorser's image positive, the endorser or his/her agency should carefully consider a sponsor's history and reputation while selecting a sponsor.OAIID:RECH_ACHV_DSTSH_NO:T201825316RECH_ACHV_FG:RR00200001ADJUST_YN:EMP_ID:A079595CITE_RATE:.694DEPT_NM:체육교육과EMAIL:[email protected]_YN:YN
Author Correction: Subnetwork representation learning for discovering network biomarkers in predicting lymph node metastasis in early oral cancer (Scientific Reports, (2021), 11, 1, (23992), 10.1038/s41598-021-03333-5)
No full text© The Author(s) 2022.In the original version of this Article, Doh Young Lee was omitted as a corresponding author. Correspondence and requests for materials should also be addressed to [email protected]
Juncos, Sparrows, and Crows in the Transnational Poetry of Shirley Geok-lin Lim
No full textThis essay explores Lim’s efforts to express and encourage inclusivity through the agency of her poetic imagination. As Lim renavigates the Pacific and other terrain and writes, she strives for a “utopian goal,” or to “voice authenticity as a signified.” Her poems advocate self-empowerment so that her nestlings can find their way in a world full of individuals of every race, creed, and gender. Lim shapes her poems to recognize the exhausting, long-term efforts a traveler or migrant must make as he or she wanders; a journey is not always finite, circular, or linear. To propel her inclusivity efforts, Lim often draws on imagery, not just of birds, but also of political movements in Hong Kong and elsewhere, natural disasters such as wildfires, or even a sunshine-filled Californian moment. She crafts her form to share her advocacy via haiku, alphabet, and prose poems. The intersections of her form, poetic imagination, and transnational crisscrossings reveal the painstaking ways in which a crosshatched identity develops and emerges over a lifetime. This article offers a bird’s eye view of some of Lim’s recent poems, mostly published after 2014, including her “Cassandra Days: Poems,” as well as works from Ars Poetica for the Day , Do You Live In? , and The Irreversible Sun , not to mention an unearthed and unpublished interview from 1985
A multifaceted perspective on skin cancer prevention
No full textSolar ultraviolet radiation has been acknowledged as the main culprit for the three major
types of skin cancer which are among the most numerous (basal cell carcinoma [BCC],
squamous cell carcinoma [SCC]) and most dangerous (cutaneous malignant melanoma)
malignancies in Caucasian populations.
The present thesis comprises six individual projects providing a multifaceted perspective on
the prevention of these tumours.
Project I evaluated a school-based sun safety education programme developed by the Swiss
Cancer Leagues. Primary school students in the Canton of Zurich (North-Eastern Switzerland)
were asked to answer a questionnaire regarding their sun-related knowledge, behaviour,
and sunburn experience shortly before and one year after the intervention (repeated cross-
sectional assessment). Based on the data from more than 3000 students, the sun safety
education programme was effective in sustainably improving children’s sun-related
knowledge and possibly to some extent in decreasing sunburn rates, but had no obvious
impact on the examined sun protective behaviours (use of sunscreen, seeking shade).
Project II represents a systematic review of cross-sectional and interventional studies on
sun-related knowledge, attitudes, and protective behaviours of outdoor workers. The 52
relevant publications identified through an electronic search of medical literature databases
(PubMed, Embase, PsycINFO) and an extensive hand search suggested that outdoor workers’
sun protective behaviours are largely inadequate and sunburn rates are high (50-80% per
season). However, there is evidence that sun safety education in outdoor occupational
settings is effective in increasing workers’ protective behaviours and presumably also in
reducing sunburn incidence.
Project III investigated sun protective behaviour and sunburn experience of vacationers
spending holidays in the tropics or subtropics. The 1165 standardised face-to-face interviews
conducted among air passengers waiting in the departure or baggage claim area at the
Airport Basel-Mulhouse (Switzerland/France) and among vacationers waiting for pre-travel
health advice at the Travel Clinic of the Swiss Tropical and Public Health Institute Basel
(Switzerland) revealed that almost all respondents used sunscreen at the holiday
destination. Nevertheless, wearing a sunhat and protective clothing as well as seeking shade
were clearly less common sun protection methods. The assessed sunburn rate among the
324 interviewed returning air passengers was alarmingly high, with 44% having suffered
from sunburn during their holiday stay.
Project IV comprehensively analysed the content and quality of 2103 print media articles
pertaining to skin cancer prevention and related topics (solaria, vitamin D) published in
Germany and Switzerland over a one-year period (2012-2013). Whereas skin cancer
secondary prevention received little press attention, primary prevention was a frequently
covered media topic. However, the delivered information was generally rather superficial. By
far the most common and often sole sun protection recommendation made was the use of
sunscreen. In total, 27% of all analysed articles contained misleading or erroneous
statements which were mostly related to the use of sunscreen and vitamin D issues.
Projects V and VI are based on data derived from the Clinical Practice Research Datalink, a
large, well-validated primary care database established in the United Kingdom (UK).
Project V estimated BCC incidence in the UK and characterised affected patients regarding
lifestyle factors and comorbidities. The calculated age-standardised BCC incidence in adults
rose from 119 to 165 per 100 000 person-years between the years 2000 and 2011. According
to the matched case-control analysis including 57 121 BCC cases and 57 121 BCC-free
controls, BCC risk was slightly increased in alcohol drinkers, but reduced in smokers and in
individuals with a body mass index outside the normal range. BCC was associated with
various comorbidities related to iatrogenic or non-iatrogenic immunosuppression.
Project VI explored whether patients regularly exposed to systemic nonsteroidal anti-
inflammatory drugs (NSAIDs) are at a reduced risk of nonmelanoma skin cancer (NMSC). The
matched case-control analysis comprised 65 398 BCC cases, 65 398 BCC-free controls, 7864
SCC cases, and 31 456 SCC-free controls. Overall, NSAID use was not negatively associated
with BCC, but when looking exclusively at users of single NSAID substances there was a
suggestion of a reduced BCC risk in regular users of aspirin and ibuprofen. SCC risk was
slightly decreased in regular users of any NSAIDs, with the strongest risk reduction observed
in current users of coxibs. These findings provide evidence that patients predisposed to
NMSC may benefit from chemoprevention with NSAIDs
Remote tactile sensing system integrated with magnetic synapse
No full textAbstractMechanoreceptors in a fingertip convert external tactile stimulations into electrical signals, which are transmitted by the nervous system through synaptic transmitters and then perceived by the brain with high accuracy and reliability. Inspired by the human synapse system, this paper reports a robust tactile sensing system consisting of a remote touch tip and a magnetic synapse. External pressure on the remote touch tip is transferred in the form of air pressure to the magnetic synapse, where its variation is converted into electrical signals. The developed system has high sensitivity and a wide dynamic range. The remote sensing system demonstrated tactile capabilities over wide pressure range with a minimum detectable pressure of 6 Pa. In addition, it could measure tactile stimulation up to 1,000 Hz without distortion and hysteresis, owing to the separation of the touching and sensing parts. The excellent performance of the system in terms of surface texture discrimination, heartbeat measurement from the human wrist, and satisfactory detection quality in water indicates that it has considerable potential for various mechanosensory applications in different environments.</jats:p
Young Sun troopers
No full textThis paper presents Young Sun Troopers, a health communications campaign by four final year undergraduates at Wee Kim Wee School of Communication and Information (WKWSCI) in Nanyang Technological University (NTU). Local skin cancer rates rose by an alarming 60% in the last decade (National Skin Centre, 2014). Dermatologist Dr. Wong Su-Ni verified that one blistering childhood sunburn doubles the risk of melanoma, a form of malignant skin cancer, in adulthood. Skin cancer is preventable, yet health agencies and the media had not shown urgency in addressing the problem. The team’s formative survey amongst 213 Singaporean parents found that nine in ten do not practise regular sun protection for their children during outdoor activities. Knowledge on irreversible sun damage is also severely inadequate. Prompted by this worrying situation, the team designed their campaign to educate parents on the importance of sun protection, and motivate them to inculcate sun-safe habits in their children.Informed by findings, the team employed a strategic communication plan to Rationalise, Persuade, and Incentivise, with the goal to convert knowledge into behavioural intent. To disseminate credible messages, they partnered with healthcare institutions, including National University Hospital (NUH) and KK Women’s and Children’s Hospital (KKH). At parks and SAFRA Clubhouses, they educated parents in the relevant context of outdoor play for sun-safe behaviours. The campaign also targeted children aged 7 to 12 through school-based intervention, so as to complement parent outreach initiatives. This strategy encouraged sustainable habits through mutual parent-child influence. Assessment of these efforts showed significant positive impact on knowledge and behavioural intent, for parents and children.Bachelor of Communication Studie
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