Empirical analysis of congestion spreading in Seoul traffic network

Understanding how local traffic congestion spreads in urban traffic networks is fundamental to solving congestion problems in cities. In this work, by analyzing the high resolution data of traffic velocity in Seoul, we empirically investigate the spreading patterns and cluster formation of traffic congestion in a real-world urban traffic network. To do this, we propose a congestion identification method suitable for various types of interacting traffic flows in urban traffic networks. Our method reveals that congestion spreading in Seoul may be characterized by a tree-like structure during the morning rush hour but a more persistent loop structure during the evening rush hour. Our findings suggest that diffusion and stacking processes of local congestion play a major role in the formation of urban traffic congestion.Comment: 10 pages, 7 figure

Global efficiency and network structure of urban traffic flows: A percolation-based empirical analysis

Making the connection between the function and structure of networked systems is one of fundamental issues in complex systems and network science. Urban traffic flows are related to various problems in cities and can be represented as a network of local traffic flows. To identify an empirical relation between the function and network structure of urban traffic flows, we construct a time-varying traffic flow network of a megacity, Seoul, and analyze its global efficiency with a percolation-based approach. Comparing the real-world traffic flow network with its corresponding null-model network having a randomized structure, we show that the real-world network is less efficient than its null-model network during rush hour, yet more efficient during non-rush hour. We observe that in the real-world network, links with the highest betweenness tend to have lower quality during rush hour compared to links with lower betweenness, but higher quality during non-rush hour. Since the top betweenness links tend to traverse the entire network, their congestion has a stronger impact on the network's global efficiency. Our results suggest that urban traffic congestion might arise when such backbone links are severely congested rather than the whole system is slowing down.Comment: 7 pages, 4 figure

Flow-Induced Voltage Generation Over Monolayer Graphene in the Presence of Herringbone Grooves

While flow-induced voltage over a graphene layer has been reported, its origin remains unclear. In our previous study, we suggested different mechanisms for different experimental configurations: phonon dragging effect for the parallel alignment and an enhanced out-of-plane phonon mode for the perpendicular alignment (Appl. Phys. Lett. 102:063116, 2011). In order to further examine the origin of flow-induced voltage, we introduced a transverse flow component by integrating staggered herringbone grooves in the microchannel. We found that the flow-induced voltage decreased significantly in the presence of herringbone grooves in both parallel and perpendicular alignments. These results support our previous interpretation

Coarsening model of cavity nucleation and thin film delamination from single-crystal BaTiO3 with proton implantation

The layer splitting mechanism of a proton implanted single crystal ferroelectric BaTiO3 thin film layer from its bulk BaTiO3 substrate has been investigated. The single crystal BaTiO3 thin film layer splits as the hydrogen gas diffuses and the internal cavity pressure increases. Ripening mechanism driven by the pressurized hydrogen in the implantation-induced damage zone makes coarsening of the cavities and causes the delamination of the thin layer during the annealing. A unique criterion relation of blister nucleation and evolution has been derived and a simplified debonding criterion is proposed in terms of dimensionless parameters based on the force equilibrium condition. A numerical simulation of two-bubble evolution and delamination of thin film is performed using a finite element method

Investigation of the SH3BP2 Gene Mutation in Cherubism

Cherubism is a rare developmental lesion of the jaw that is generally inherited as an autosomal dominant trait. Recent studies have revealed point mutations in the SH3BP2 gene in cherubism patients. In this study, we examined a 6-year-old Korean boy and his family. We found a Pro418Arg mutation in the SH3BP2 gene of the patient and his mother. A father and his 30-month-old younger brother had no mutations. Immunohistochemically, the multinucleated giant cells proved positive for CD68 and tartrate-resistant acid phosphatase (TRAP). Numerous spindle-shaped stromal cells expressed a ligand for receptor activator of nuclear factor kB (RANKL), but not in multinucleated giant cells. These results provide evidence that RANKL plays a critical role in the differentiation of osteoclast precursor cells to multinucleated giant cells in cherubism. Additionally, genetic analysis may be a useful method for differentiation of cherubism.</p

Experimental Study on Coordinated Heading Control of Four Vessels Moored Side by Side

A floating type liquefied natural gas (LNG) bunkering terminal has been under development in Korea since 2014; the terminal is designed to receive LNG from an LNG carrier (LNGC) and transfer it to two other LNG bunkering shuttles (LNGBS) simultaneously. The operational feasibility of the LNG loading and unloading processes has been confirmed. When four vessels are moored side by side with mooring ropes and fenders, their positions must be maintained within the designed allowable criteria. In addition, the floating bunkering terminal (FLBT) has its own mooring system, an internal turret with catenary mooring lines and stern tunnel thrusters to maintain its own position and control the vessel heading. In this study, we investigated the operational feasibility of the FLBT during the LNG loading and unloading operations with four vessel mooring configurations and heading controls. A series of model tests was done in the ocean engineering basin of the Korea Research Institute of Ships and Ocean engineering. The motion responses of the four vessels were determined using an optical measurement system, and the tensile loads on ship-to-ship mooring ropes and the compressive loads on ship-to-ship fenders were measured using one-axis load cells. A white noise test was done and the results were compared with the numerical results for the purpose of validation. Then, four combined environmental conditions were presented both without heading control and with several heading control cases. Finally, we determined the available safe bunkering heading ranges taking into account the tensile loads on the mooring ropes

The Influence of Tibial Positioning on the Diagnostic Accuracy of Combined Posterior Cruciate Ligament and Posterolateral Rotatory Instability of the Knee

Background: To determine if tibial positioning affects the external rotation of the tibia in a dial test for posterolateral rotatory instability combined with posterior cruciate ligament (PCL) injuries. Methods: Between April 2007 and October 2007, 16 patients with a PCL tear and posterolateral rotatory instability were diagnosed using a dial test. The thigh-foot angle was measured at both 30 ° and 90 ° of knee fl exion with an external rotation stress applied to the tibia in 2 different positions (reduction and posterior subluxation). The measurements were performed twice by 2 orthopedic surgeons. Results: In posterior subluxation, the mean side-to-side difference in the thigh-foot angle was 11.56 ± 3.01 ° at 30 ° of knee fl exion and 11.88 ± 4.03 ° at 90 ° of knee flexion. In the sequential dial test performed with the tibia reduced, the mean side-to-side difference was 15.94 ± 4.17 ° (p &lt; 0.05) at 30 ° of knee fl exion and 16.88 ± 4.42 ° (p = 0.001) at 90 ° of knee fl exion. The mean tibial external rotation was 5.31 ± 2.86 ° and 6.87 ± 3.59 ° higher in the reduced position than in the posterior subluxation at both 30° and 90 ° of knee fl exion. Conclusions: In the dial test, reducing the tibia with an anterior force increases the ability of an examiner to detect posterolateral rotary instability of the knee combined with PCL injuries

Vocoder-free End-to-End Voice Conversion with Transformer Network

Mel-frequency filter bank (MFB) based approaches have the advantage of learning speech compared to raw spectrum since MFB has less feature size. However, speech generator with MFB approaches require additional vocoder that needs a huge amount of computation expense for training process. The additional pre/post processing such as MFB and vocoder is not essential to convert real human speech to others. It is possible to only use the raw spectrum along with the phase to generate different style of voices with clear pronunciation. In this regard, we propose a fast and effective approach to convert realistic voices using raw spectrum in a parallel manner. Our transformer-based model architecture which does not have any CNN or RNN layers has shown the advantage of learning fast and solved the limitation of sequential computation of conventional RNN. In this paper, we introduce a vocoder-free end-to-end voice conversion method using transformer network. The presented conversion model can also be used in speaker adaptation for speech recognition. Our approach can convert the source voice to a target voice without using MFB and vocoder. We can get an adapted MFB for speech recognition by multiplying the converted magnitude with phase. We perform our voice conversion experiments on TIDIGITS dataset using the metrics such as naturalness, similarity, and clarity with mean opinion score, respectively.Comment: Work in progres

Experimental Study on the Flexural Capacity of H-shaped Steel Beam with the Concrete-Filled Tubular Flange

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