실리콘 카바이드에 대한 CO2 레이저 연마의 효과

학위논문(석사)--서울대학교 대학원 :공과대학 기계항공공학부,2019. 8. 안성훈.실리콘 카바이드 (SiC)는 일반적으로 사용되는 다른 유리 및 금속보다 많은 장점을 제공하기 때문에 오랫동안 고성능 광학 응용 분야에서 우수한 재료로 인정 받고 있다. SiC의 우수한 특성 중 일부는 매우 높은 고유 강성 (E / ρ), 높은 열 전도성 및 뛰어난 치수 안정성을 포함한다. 실리콘 카바이드에 대한 CO2 레이저 연마와 레이저의 공구 경로의 효과가 조사했다. 이 하이브리드 과정에는 먼저 원하는 패턴에 레이저 크랙을 냈다. 이어서, 레이저 보조 연마가 동일한 공구 경로에서 수행되다. 표면은 레이저 유도 크랙이 있는 영역과 크랙이 없는 영역에서 물질 제거에 있어 뚜렷한 차이를 보였다.. 이러한 물질 제거의 높은 차이는 매크로 및 미세 패턴을 가공하기 위해서 사용되었다. 폭은 2 mm에서 200 μm까지, 그리고 깊이는 5 μm에서 20 μm까지 홈이 성공적으로 생성되었다. 또한, 이 하이브리드 과정은 나중에 Newtonian 망원경의 일부로 사용되는 구형 오목 거울을 가공하는 데 사용된다.Silicon carbide (SiC) has long been recognized as an excellent material for high performance optical applications because it offers many advantages over other commonly used glasses and metals. Some of the superior attributes of SiC include extremely high specific stiffness (E/ρ), high thermal conductivity and outstanding dimensional stability. The effect of and CO2 laser and its tool path on silicon carbide (SiC) were investigated. The process started by creating Laser induced cracks on the desired pattern. Subsequently, laser assisted polishing was conducted on the same tool path. The surface showed a sharp difference in material removal in the areas with laser induced cracks and in areas with no cracks. This high difference in material removal was used to generate macro and micro patterns. Grooves from 2mm to 200μm in width and 5μm to 20μm depth were successfully generated. Moreover, this process was used to machine a spherical concave mirror that was later used as part of a Newtonian telescope.Chapter 1. Introduction 1 1.1 Purpose of Research 1 1.2 Surface Texture on Ceramics 3 1.2 Hybrid Machining Processes 3 Chapter 2. Experiment Set up 5 2.1 Hardware Set-Up 5 Chapter 3. Material Removal Rate 7 3.1 CO2 Laser Generated Cracks 7 3.2 Experiment Design 9 3.3 Material Removal Measurement and Results 12 Chapter 4. Macro/Micro Channels 17 4.1 Macro/Micro Channels Design 17 4.2 Tool Size Effect 19 4.3 Variable Width Channel 20 4.4 Tool Path Effect 22 Chapter 5. Newtonian Telescope 25 5.1 Mirror Design and Fabrication 25 5.2 Newtonian Telescope 28 Chapter 6. Conclusion 31 Bibliography 32 Abstract in Korean 34Maste

Aditivacion de resinas epoxi mediante complejos poliméricos homo y heterometálicos con 1,3,5-triaza-7-fosfaadamantanofosfina (PTA) y 3,7-dimetil-1,3,7-triaza-5-phosphabiciclo[3.3.1]nonane (dmoPTA)

Publication number: ES2627009 A1 (26.07.2017) Also published as: ES2627009 B2 (22.01.2018) Application number: P201600099 (26.01.2016)La presente invención se relaciona con el uso de polímeros homo y heterometálicos con el ligando 1,3,5-triaza-7-fosfaadamantanofosfina (PTA) y 3,7-dimetil-1,3,7-triaza-5-phosphabiciclo[3.3.1]nonane) (dmoPTA), como aditivos de resinas epoxídicas. Estos aditivos previa disolución o suspensión mejoran y modifican las propiedades de las resinas confiriéndoles nuevas propiedades como color, conductividad eléctrica y magnética, resistencia térmica y al fuego, flexibilidad, distinto tiempo de curado, entre otras propiedades.Universidad de Almerí

Olfactory function in focal epilepsies: Understanding mesial temporal lobe epilepsy beyond the hippocampus

Several lines of research have linked olfactory regions with the pathophysiology of focal epilepsies. Among those regions, the piriform cortex represents the major part of the primary olfactory cortex. According to these data, we raised the hypothesis that in patients with mesial temporal lobe epilepsy associated with hippocampal sclerosis exists an interictal dysfunction of olfactory processing that could be more significant compared to patients with extra‐hippocampal focal epilepsy and healthy controls. This could be the consequence of a dysfunctional epileptogenic network that extends beyond the hippocampus and affects other structures, including the piriform cortex. To test this hypothesis, we evaluated the olfactory function with the Sniffin' Sticks test in 32 patients with mesial temporal lobe epilepsy associated with hippocampal sclerosis, 30 patients with extra‐hippocampal focal epilepsy, and 22 healthy controls. Compared to the other study groups, patients with temporal lobe epilepsy due to hippocampal sclerosis showed a basal olfactory dysfunction characterized by an impairment in odor discrimination and odor identification. We also found that high seizure frequency had a strong correlation with the evaluated olfactory tasks. Our results are consistent with neuroimaging and neuropathological data that establish a link between olfactory regions and the pathophysiology of temporal lobe epileps

Epidermal Barrier Function and Skin Homeostasis in Skin with Permanent and Adhesive Tattoos: A Cross-Sectional Study

Tattoos are a current trend, but their impact on skin homeostasis and epidermal barrier function is not well known. So, the aims of this study are (1) to investigate epidermal barrier function and skin homeostasis in skin with permanent tattoos, adhesive temporary tattoos and non-tattooed skin, and (2) to analyze the effect of petrolatum on skin with permanent and adhesive tattoos. In total, 67 tattoos were enrolled (34 permanent tattoos and 33 adhesive tattoos). Temperature, transepidermal water loss (TEWL), stratum corneum hydration (SCH), erythema and total antioxidant capacity (TAC) were measured in skin with permanent tattoos, adhesive tattoos and non-tattooed skin before and after petrolatum application. The temperature was lower (30.47 C vs. 31.01 C; p = 0.001) on skin with permanent tattoos than non-tattooed skin, while SCH (48.24 Arbitrary Units (AU) vs. 44.15 AU; p = 0.008) was higher. Skin with adhesive tattoos showed lower temperature, SCH (21.19 AU vs. 41.31 AU; p < 0.001) and TAC (1.27 microcoulombs (uC) vs. 3.48 uC; p < 0.001), and higher TEWL (8.65 g/h/m2 vs. 6.99 g/h/m2; p = 0.003), than non-tattooed skin. After petrolatum application, the temperature decreased on skin with permanent tattoos, and TEWL and SCH decreased on skin with adhesive tattoos. Adhesive tattoos may affect skin barrier function, while permanent tattoos may have a lower impact. Tattooed and non-tattooed skin responds in different ways to moisturizers

Treatment of apicomarginal defect with periapical surgery : a case report

An apicomarginal defect can be explained as a total loss of buccal alveolus extending from the original crestal bone to the apex of the tooth. This study presents a case of an apicomarginal defect in a first left molar subjected to periapical surgery with vestibular cortex block replacement and A-PRF + membrane coating approximately one year ago. One-year clinical follow-up was performed, with no evidence of recurrence. This case report discusses periapical surgical treatment and the importance of an interdisciplinary approach to the management of teeth with apicomarginal defects

Two Neolithic structures at the archaeological site of Casa Garrido Nord II (Moixent, Valencia)

Es presenten les restes de cronologia neolítica documentades a les obres de canalització de gas a la vall de Montesa. Concretament, dues sitges del Neolític II de la seqüència regional, aparegudes al jaciment de Casa Garrido Nord, al terme municipal de Moixent. Encara que els materials són poc significatius, es tracta de les primeres estructures de cronologia neolítica, de les quals tenim constància, en què s’ha realitzat una excavació arqueològica sistemàtica a la comarca de la Costera. Paraules clau: Casa Garrido Nord II. Sitja. Neolític II. La Costera. Assentaments en pla.Es presenten les restes de cronologia neolítica documentades a les obres de canalització de gas a la vall de Montesa. Concretament, dues sitges del Neolític II de la seqüència regional, aparegudes al jaciment de Casa Garrido Nord, al terme municipal de Moixent. Encara que els materials són poc significatius, es tracta de les primeres estructures de cronologia neolítica, de les quals tenim constància, en què s’ha realitzat una excavació arqueològica sistemàtica a la comarca de la Costera. Paraules clau: Casa Garrido Nord II. Sitja. Neolític II. La Costera. Assentaments en pla.Herewith we submit the remains of Neolithic chronology found at the gas piping works performed at the Valley of Montesa (Valencia). They are specifically two Neolithic II underground storage places of a regional sequence, which appeared at the Casa Garrido Nord archaeological site, within the Moixent municipal borough (in the province of Valencia). Although the materials are not very meaningful, they represent the first structures of Neolithic chronology known to us, and therefore we have carried out a systematic archaeological excavation in the area of La Costera (Valencia). Key words: Casa Garrido Nord II. Silo. Neolithic II. La Costera. Settlements on flat lands

Contribution of active commuting to and from school to device-measured physical activity levels in young people: A systematic review and meta-analysis

Spanish Ministry of Universities, Grant/Award Number: FPU18/04251; Spanish Ministry of Economy, Industry and Competitiveness and the European Regional Development Fund, Grant/Award Number: DEP2016- 75598- R; MCIN/AEI/ and "ERDF a way of making Europe" European Union, Grant/Award Number: PID2021- 126126OA- I00; University of Granada Plan Propio de Investigación 2016—Excellence actions: Unit of Excellence on Exercise and Health (UCEES); Junta de Andalucía, Consejería de Conocimiento, Investigación y Universidades, European Regional Development Fund, Grant/Award Number: SOMM17/6107/UGR. Pablo Campos-Garzón is supported by FPU18/04251 from the Spanish Ministry of Universities. This study is part of a PhD thesis conducted in the Biomedicine Doctoral Studies program of the University of Granada, Spain. Funding for open access charge: Universidad de Granada/CBUA.Objective: To analyze the contribution of active commuting to and from school (ACS) to device-measured light physical activity (LPA) and moderate-to-vigorous physical activity (MVPA) levels in young people aged 6 to 18 years old, as well as, in both trip directions (i.e., home-school, school-home). Methods: This systematic review was conducted according to the PRISMA statement, and five different databases were used for the systematic search (PubMed, Web of Science, SPORTdiscuss, Cochrane Library, and National Transportation Library) using PECO strategy. Results: A total of 14 studies met all the eligibility criteria, which compile 7127 participants. The overall ACS weighted LPA was 19.55 min (95% CI: 3.84-35.26; I2 = 99.9%, p < 0.001) and 68.74 min (95% CI: 6.09-131.39; z = 2.15, p = 0.030) during the home-school and school-home trips, respectively. For MVPA, the overall ACS weighted MVPA was 8.98 min (95% CI: 5.33–12.62; I2 = 99.95%, p < 0.001) during the home-school trip and 20.07 min (95% CI: 13.62-26.53; I2 = 99.62%, p < 0.001) during the school-home trip. Conclusion: ACS may contribute about 48% of the PA recommendations in young people on school days if both trip directions are actively performed. Therefore, future studies aimed at increasing daily PA levels in young population should focus on promoting students' ACS. PROSPERO registration number: CRD42020162004A.Spanish Ministry of Universities, FPU18/04251Spanish Ministry of Economy, Industry and Competitiveness and the European Regional Development Fund, DEP2016- 75598- RMCIN/AEI/"ERDF a way of making Europe" European Union, PID2021- 126126OA- I00University of GranadaJunta de AndalucíaEuropean Regional Development Fund, SOMM17/6107/UGRUniversidad de Granada/CBU

Lessons learned from the deployment of a multihop IEEE 802.11g testbed using COTS devices

Proceedings of: 2010 European Wireless Conference (EW2010), (April 12-15, 2010), Lucca, ItalyA lot of attention has been given to multihop wireless networks lately, but further research is needed. This attention has motivated an increase in the number of 802.11- based deployments, both indoor and outdoor. These testbeds are used to run measurements in order to analyze and understand the limitation and differences between analytical or simulationbased figures and the results from real-life experimentation. In this paper we describe the lessons learned from the deployment of a wireless multihop testbed under the false floor of a laboratory in our Computer Science building. We assess the radio shielding provided by the false floor panels, and run exhaustive and controlled experiments to analyze the performance limits of commercial off-the-shelf hardware. The results obtained confirm that experimental measurements can severely deviate from the expected theoretical values.European Community's Seventh Framework ProgramPartly funded by the Ministry of Science and Innovation of Spain, under the QUARTET project (TIN2009-13992-C02-01)Publicad

Machine learning for mortality analysis in patients with COVID-19

This paper analyzes a sample of patients hospitalized with COVID-19 in the region of Madrid (Spain). Survival analysis, logistic regression, and machine learning techniques (both supervised and unsupervised) are applied to carry out the analysis where the endpoint variable is the reason for hospital discharge (home or deceased). The different methods applied show the importance of variables such as age, O2 saturation at Emergency Rooms (ER), and whether the patient comes from a nursing home. In addition, biclustering is used to globally analyze the patient-drug dataset, extracting segments of patients. We highlight the validity of the classifiers developed to predict the mortality, reaching an appreciable accuracy. Finally, interpretable decision rules for estimating the risk of mortality of patients can be obtained from the decision tree, which can be crucial in the prioritization of medical care and resources.This research was funded by Agencia Estatal de Investigación AEI/FEDER Spain, Project PGC2018-095895-B-I00, and Comunidad Autónoma de Madrid, Spain, Project S2017/BMD-368