A triangulation-invariant method for anisotropic geodesic map computation on surface meshes

pre-printThis paper addresses the problem of computing the geodesic distance map from a given set of source vertices to all other vertices on a surface mesh using an anisotropic distance metric. Formulating this problem as an equivalent control theoretic problem with Hamilton-Jacobi-Bellman partial differential equations, we present a framework for computing an anisotropic geodesic map using a curvature-based speed function. An ordered upwind method (OUM)-based solver for these equations is available for unstructured planar meshes. We adopt this OUM-based solver for surface meshes and present a triangulation-invariant method for the solver. Our basic idea is to explore proximity among the vertices on a surface while locally following the characteristic direction at each vertex. We also propose two speed functions based on classical curvature tensors and show that the resulting anisotropic geodesic maps reflect surface geometry well through several experiments, including isocontour generation, offset curve computation, medial axis extraction, and ridge/valley curve extraction. Our approach facilitates surface analysis and processing by defining speed functions in an application-dependent manner

The Effects of Top Management Team External Ties and Board Composition on the Strategic Choice of Late Movers

Within the context of the monitoring and control function of the board, we extend previous work on the agency view of governance. We examine how the top managers\u27 external ties and board composition directly and interactively influence the strategic choices of firms. Our results indicate that top managers with intra-industry knowledge and experience tend to adopt a resource-imitation strategy whereas those with knowledge and experience from other industries tend to adopt a resource-substitution strategy. The separation of CEO and board chairperson duties also affects strategy selection. In terms of interaction effects, we find that boards with a high ratio of outsiders reduce the tendencies of managers to opt for the safe strategy solutions with which they are familiar

Clinical analysis of pediatric patients who visited Masan Samsung Emergency Center

Purpose : Through a clinical and retrospective analysis of pediatric patients who visited the Regional Emergency Medical Center of Masan Samsung Hospital from January 2007 to December 2008, we characterized pediatric and adolescent emergency patients to improve emergency care in future. Methods : We reviewed the medical records of 14,065 pediatric patients below 19 years of age. Results : The male to female ratio was 1.5:1, and the most common age group was less than 3 years (49.6%). The peak month was May (10.0%), the peak day of the week was Sunday (24.7%), and the peak time of day was 20:00&amp&#59;#8211&#59;20:59 (8.5%). There was no difference in the number of visits per day based on weather (sunny, rain [below 10 mm per day], snow, and fog) or daily temperature difference&#59; however, visits increased on sandy, dusty days and decreased on rainy days with more than 10 mm of rain per day. Based on the international classification of disease (ICD)-10 system, the most common disease code was code R (symptoms, sign, and abnormal clinical laboratory finding) (31.5%), and the most common symptom was fever (13.1%). Final outcomes were discharged (73.8%), admitted (25.7%), transferred (0.4%), and expired (0.1%). In adolescent patients aged 15&amp&#59;#8211&#59;19 years, the most common disease code was Injury &amp&#59; Poisoning (code S&amp&#59;T, 36.9%)&#59; the most common symptom was abdominal pain (9.6%). Conclusion : Pediatric patients visiting the emergency center were most likely to be male and under 3 years of age and to visit between 20:00 and 21:00 on Sundays and in May, and the most common symptom was fever. Differences between adolescents and pediatric patients showed that adolescents had a higher visiting rate with abdominal pain and a larger temperature difference

Learning Multi-Task Transferable Rewards via Variational Inverse Reinforcement Learning

Many robotic tasks are composed of a lot of temporally correlated sub-tasks in a highly complex environment. It is important to discover situational intentions and proper actions by deliberating on temporal abstractions to solve problems effectively. To understand the intention separated from changing task dynamics, we extend an empowerment-based regularization technique to situations with multiple tasks based on the framework of a generative adversarial network. Under the multitask environments with unknown dynamics, we focus on learning a reward and policy from the unlabeled expert examples. In this study, we define situational empowerment as the maximum of mutual information representing how an action conditioned on both a certain state and sub-task affects the future. Our proposed method derives the variational lower bound of the situational mutual information to optimize it. We simultaneously learn the transferable multi-task reward function and policy by adding an induced term to the objective function. By doing so, the multi-task reward function helps to learn a robust policy for environmental change. We validate the advantages of our approach on multi-task learning and multi-task transfer learning. We demonstrate our proposed method has the robustness of both randomness and changing task dynamics. Finally, we prove that our method has significantly better performance and data efficiency than existing imitation learning methods on various benchmarks.Comment: Accepted in ICRA 202

Determinant Factors of Pedestrian Volume in Different Land-Use Zones: Combining Space Syntax Metrics with GIS-Based Built-Environment Measures

This study combined space syntax metrics and geographic information systems (GIS)-based built-environment measures to analyze pedestrian volume in different land-use zones, as recorded in unique public data from a pedestrian volume survey of 10,000 locations in Seoul, Korea. The results indicate that most of the built-environment variables, such as density, land use, accessibility, and street design measures, showed statistically significant associations with pedestrian volume. Among the syntactic variables, global integration showed a statistically significant association with the average pedestrian volume in residential and commercial zones. In contrast, local integration turned out to be an important factor in the commercial zone. Therefore, this study concludes that the syntactic variables of global and local integration, as well as some built-environment variables, should be considered as determinant factors of pedestrian volume, though the effects of those variables varied by land-use zone. Therefore, planning and public policies should use tailored approaches to promote urban vitality through pedestrian volume in accordance with each land-use zone’s characteristics

Advancing Large-area Perovskite Module Fabrication: A Bar-coating Approach for Efficiency and Stability

School of Energy and Chemical Engineering (Energy Engineering)Organic-inorganic halide perovskites solar cells (PSCs) have attracted a great deal of interest over the last several years due to their rapid development in power conversion efficiency (PCE), increasing from 3.5% to 25.8% in a decade. In particular, the solution processability is one of the most important advantages when utilizing perovskites, which in turn allows usage of large-area coating process. However, one major obstacle to commercializing perovskite is the low performance efficiency for large- area perovskite modules compared to the small-area PSCs due to the difficulty in controlling the quality of the perovskite layer in a scalable coating. The nucleation and the crystal growth affect the morphology of the perovskite thin film and a number of traps in the bulk and the surface of the perovskite layer severely limit the PCE of the device. The work of this thesis elucidates diverse issues regarding the morphology control of perovskite nanocrystals, the stabilization of the a-phase perovskite, and the reduction of defects in bulk perovskite and perovskite surface. The crystallization mechanism of large-area perovskite bar-coating is investigated, revealing that solvent removal by an air-knife is in principle the same as the anti-solvent dripping in small-area perovskite spin-coating. From the experiments, the quick removal of solvent and the control of the intermediate phase are revealed to play a pivotal role in producing high-quality films. A balance of fast nucleation and slow crystal growth contributes to the formation of a dense and uniform perovskite. The addition of the quaternary ammonium halide salt to a perovskite solution is devised to stabilize the a-phase perovskite and passivate the trap sites in the bulk perovskite. A highly polar nature with a large dipole moment due to the coexistence of electron-rich and electron-deficient moieties, helps effectively passivate charge defects. In addition, quaternary ammonium characteristic make the a-phase perovskite stable because it is hardly deprotonated. Finally, the sequential surface treatment is conducted on formamidinium lead iodide perovskite photovoltaic devices. An investigation is fulfilled to study the impact of each surface treatment on surface defect passivation and carrier transport facilitation. Two surface treatments were effective in both reducing in defects and boosting carrier extraction, but each surface treatment had a more effective part. By maximizing the synergy of two surface treatments, a highly efficient and stable large-area perovskite device can be realized.clos

Microcatheter looping technique for catheterization of the proper hepatic artery through pancreaticoduodenal arcades and gastroduodenal artery in celiac axis occlusion

AbstractThe present report describes a case of successful embolization of the hepatic artery pseudoaneurysm in a 61-year-old female patient with celiac axis occlusion. Because of celiac artery occlusion, the hepatic artery had to be catheterized through the pancreaticoduodenal arcades and the gastroduodenal artery (GDA) from the superior mesenteric artery (SMA). Despite coaxial catheterization using a torque guide wire, the proper hepatic artery (PHA) could not be catheterized because of the acute angle between the GDA and the PHA. The use of the microcatheter looping technique facilitated catheterization of the PHA and subsequent embolization of the right hepatic artery pseudoaneurysm