1,376 research outputs found
고장수목분석을 위한 향상된 퍼지 집합 개발에 관한 연구
No full text학위논문(석사) - 한국과학기술원 : 원자력공학과, 2000.2, [ vii, 52 p. ]In fault tree analysis, the conventional approach is Monte-Carlo simulation by assuming a probability distribution for the failure probability. However, it is often very difficult to estimate precise failure rates or failure probabilities of individual components or failure events. Moreover, it isn``t used in case available data are insufficient. To overcome these disadvantages, the fuzzy set theory has been applied to fault-tree analysis. But, there is much difference between values estimated with previous fuzzy sets those estimated with Monte-Carlo simulation and previous fuzzy sets have a lot of uncertainty. In addition, in case of the system where components with sufficient data and components with insufficient data are mixed, these aren``t utilized. Because of the difference between the shape of fuzzy set and that of probability distribution, these problems appear.
An improved fuzzy set approach to fault tree analysis has been developed. Its shape is made to approximate shape of the probability distribution and represented as μ(x) = f(ln(x)). It was applied to three system of WASH-1400. The results show that values calculated with improved fuzzy set approximate those calculated with Monte-Carlo Method and have better accuracy than values calculated with triangular fuzzy set in the 90% confidence limit for the top event failure probability. Furthermore, in case of FIM(fuzzy importance measure), FIM estimated with improved fuzzy set relatively approximate FIM estimated with probability distribution. Therefore, improved fuzzy set approach shows new possibility, that is, probability method and fuzzy set method may be combined.한국과학기술원 : 원자력공학과
Radiographic Measurements Associated With Ankle Power Generation During Gait in Patients With Cerebral Palsy
No full textBackground:Pes planovalgus (PV) deformity accounts for lever arm dysfunction and compromises gait in patients with cerebral palsy (CP). However, the association between ankle power generation and radiographic indices is not yet understood. We aimed to investigate the association between ankle power and radiographic indices during gait in patients with CP concomitant with PV deformity.Methods:Patients older than 14 years with ambulatory CP and PV deformity were included. All the patients underwent 3-dimensional gait analysis and weight-bearing foot radiography. Gait data were collected, including foot progression angle, tibial rotation, hip rotation, and ankle power generation. Radiographic measurements included anteroposterior (AP) talo-first metatarsal angle, lateral talo-first metatarsal angle, and hindfoot angle. A linear mixed-effects model was performed to identify significant radiographic indices associated with ankle power generation.Results:Thirty-one limbs from 15 patients with spastic diplegia and 6 with spastic hemiplegia were included. Statistical analysis demonstrated that ankle power generation was significantly correlated with the CP type (P=0.0068) and AP talo-1st metatarsal angle (P=0.0230).Conclusion:Ankle power generation was significantly associated with the AP talo-first metatarsal angle. Surgeons might need to pay attention to correcting forefoot abduction to restore ankle power when planning surgeries for pes PV deformities in patients with CP.Level of Evidence:Prognostic Level III
Effect of Surface Structure Complexity on Interfacial Droplet Behavior of Superhydrophobic Titanium Surfaces for Robust Dropwise Condensation
No full textIn general, the dropwise condensation supported by superhydrophobic surfaces results in enhanced heat transfer relative to condensation on normal surfaces. However, in supersaturated environments that exceed a certain supersaturation threshold, moisture penetrates the surface structures and results in attached condensation, which reduces the condensation heat transfer efficiency. Therefore, when designing superhydrophobic surfaces for condensers, the surface structure must be resistant to attached condensation in supersaturated conditions. The gap size and complexity of the micro/nanoscale surface structure are the main factors that can be controlled to maintain water repellency in supersaturated environments. In this study, the condensation heat exchange performance was characterized for three different superhydrophobic titanium surface structures via droplet behavior (DB) mapping to evaluate their suitability for power plant condensers. In addition, it was demonstrated that increasing the surface structure complexity increases the versatility of the titanium surfaces by extending the window for improved heat exchange performance. This study demonstrates the usefulness of DB mapping for evaluating the performance of superhydrophobic surfaces regarding their applicability for industrial condenser systems.11Nsciescopu
Synthesis of Bi2Te3 Single Crystals with Lateral Size up to Tens of Micrometers by Vapor Transport and Its Potential for Thermoelectric Applications
No full textBismuth telluride (Bi 2 Te 3 ) has recently attracted significant attention owing to its unique physical properties as a three-dimensional topological insulator and excellent properties as a thermoelectric material. Meanwhile, it is important to develop a synthesis process yielding high-quality single crystals over a large area to study the inherent physical properties and device applications of two-dimensional materials. However, the maturity of Bi 2 Te 3 vapor-phase synthesis is not good, compared to those of other semiconductor two-dimensional crystals. In this study, therefore, we report the synthesis of relatively large-area Bi 2 Te 3 crystals by vapor transport method, and we investigated the key process parameters for a synthesis of relatively thin and large-area Bi 2 Te 3 crystals. The most important factor determining the crystal synthesis was the temperature of the substrate. A Bi 2 Te 3 device exhibited a considerable photocurrent when the laser was irradiated inside the electrode area. This indicated that the photo-thermoelectric effect was the main mechanism of generation of photocurrent. The estimated Seebeck coefficient of the device was ∼196 μV/K, which is comparable to the previously reported high Seebeck coefficient of Bi 2 Te 3 . This synthesis method can guide the development and applications of various types of layered crystals with the space group of R3̄m. © Copyright 2019 American Chemical Society.1
Intrinsic functional connectivity of blue and red brains: neurobiological evidence of different stress resilience between political attitudes
No full textConservatives are more sensitive to threatening/anxious situations in perceptual and cognitive levels, experiencing emotional responses and stress, while liberals are more responsive to but tolerant of ambiguous and uncertain information. Interestingly, conservatives have greater psychological wellbeing and are more satisfied with their lives than liberals despite their psychological vulnerability to stress caused by threat and anxiety sensitivities. We investigated whether conservatives have greater resilience and self-regulation capacity, which are suggested to be psychological buffers that enhance psychological well-being, than liberals and moderates. We also explored associations between intrinsic functional brain organization and these psychological resources to expand our neurobiological understanding of self-regulatory processes in neuropolitics. We found that conservatives, compared to liberals and moderates, had greater psychological resilience and self-regulation capacity that were attributable to greater impulse control and causal reasoning. Stronger intrinsic connectivities between the orbitofrontal cortex (OFC) and precuneus and between the insula and frontal pole/OFC in conservatives were correlated with greater resilience and self-regulation capacity. These results suggest the neural underpinnings that may allow conservatives to manage the psychological stress and achieve greater life satisfaction. This study provides neuroscientific evidence for the different responses of liberals and conservatives to politically relevant social issues.Y
Adenoma of the nonpigmented ciliary epithelium presenting with recurrent iridocyclitis: unique expression of glial fibrillary acidic protein
No full textope
sj-docx-1-wso-10.1177_17474930231158211 – Supplemental material for Optimal use of antithrombotic agents in ischemic stroke with atrial fibrillation and large artery atherosclerosis
No full textSupplemental material, sj-docx-1-wso-10.1177_17474930231158211 for Optimal use of antithrombotic agents in ischemic stroke with atrial fibrillation and large artery atherosclerosis by Tae Jung Kim, Ji Sung Lee, Jae Sun Yoon, Mi Sun Oh, Ji-Woo Kim, Soo-Hyun Park, Keun-Hwa Jung, Hyun Young Kim, Jee-Hyun Kwon, Hye-Yeon Choi, Hahn Young Kim, Kyung Yoon Eah, Sang Won Han, Hyung-Geun Oh, Young-Jae Kim, Byoung-Soo Shin, Chang Hun Kim, Chi Kyung Kim, Jong-Moo Park, Kyung Bok Lee, Tai Hwan Park, Jun Lee, Man-Seok Park, Jay Chol Choi, Chulho Kim, Dong-Ick Shin, Soo Joo Lee, Dong-Eog Kim, Jae-Kwan Cha, Eung-Gyu Kim, Kyung-Ho Yu, Keun-Sik Hong, Young-Seok Lee, Ju-Hun Lee, Sung Il Sohn, Hee-Joon Bae, Young-Bae Lee, Jun Hong Lee, Joung-Ho Rha, Byung-Chul Lee, Dae-Il Chang, Sang-Bae Ko and Byung-Woo Yoon in International Journal of Stroke</p
Highly entangled hollow TiO2 nanoribbons templating diphenylalanine assembly
No full textWe introduce a biotemplating approach for creating highly entangled hollow TiO2 nanoribbons by combining peptide assembly with an atomic layer deposition process. An aromatic peptide of diphenylalanine was readily assembled into a hierarchical organogel consisting of highly entangled nanoribbons. Unlike ordinary biomaterials, the peptide nanoribbon framework exhibited a high level of thermal stability, such that it may undergo the further functionalization process of vacuum deposition without significant damage to its nanoscale structure. A nanoscale layer of anatase TiO2 was deposited on the nanoribbon framework by means of atomic layer deposition. After pyrolysis, a highly entangled nanotubular TiO2 framework was created successfully. The highly entangled TiO2 architecture exhibited UV-switchable wetting properties.This work was supported by the second stage of the Brain
Korea 21 Project, National Research Laboratory Program
(R0A-2008-000-20057-0), the KAIST EEWS Initiative (No.
EEWS0903, EEWS: Energy, Environment, Water, and
Sustainability), the Fundamental R&D Program for Core
Technology of Materials, and the National Core Research
Center Program (R15-2006-022-01001-0) funded by the Korean
government
High performance back channel etch metal oxide thin-film transistor with double active layers
No full textWe fabricated high performance back channel etch (BCE) IZO/AIZTO double-layer channel oxide thin-film transistors (TFTs) and analyzed their electrical characteristics and photo-stability of the devices. The field-effect mobility of 53.2 cm2/Vs was obtained, and we expect IZO/AIZTO double-layer BCE TFT can be used as a backplane devices for next generation high performance display applications
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