Kyungpook National University

About: Kyungpook National University is a education organization based out in Daegu, South Korea. It is known for research contribution in the topics: Population & Large Hadron Collider. The organization has 20497 authors who have published 42107 publications receiving 834608 citations.

Utilization of a unitary transform for efficient computation in the matrix pencil method to find the direction of arrival

Abstract: In this study, we use the matrix pencil (MP) method to compute the direction of arrival (DOA) of the signals using a very efficient computational procedure in which the complexity of the computation can be reduced significantly by using a unitary matrix transformation. This method applies the technique directly to the data without forming a covariance matrix. Simulation results show that the variance of the estimate approaches to the Cramer-Rao lower bound. Using real computations through the unitary transformation for the MP method leads to a very efficient computational methodology for real time implementation on a digital signal processor chip. A unitary transform can convert the complex matrix to a real matrix along with their eigenvectors and thereby reducing the computational cost at least by a factor of four without sacrificing accuracy. This reduction in the number of computations is achieved by using a transformation, which maps centro-hermitian matrices to real matrices. This transformation is based on Lee's work on centro-hermitian matrices.

PLL-Based Seamless Transfer Control Between Grid-Connected and Islanding Modes in Grid-Connected Inverters

Abstract: This paper proposes a phase-locked loop (PLL)-based seamless transfer control method between grid-connected and islanding modes in a three-phase grid-connected inverter. The PLL is used to synchronize the phase of the load voltage to a grid voltage in grid-connected operation, and to generate an angle with the desired frequency in islanding operation. The stability of both the grid current loop for grid-connected operation and the load voltage control loop for islanding operation is analyzed. The phase and magnitude of the load voltage are successively matched to the grid voltage for a seamless transfer from islanding to grid-connected operation. When grid voltage sag occurs, an operating sequence including a PLL operation is suggested in order to transfer smoothly to islanding operation and to provide a stable and seamless voltage to a sensitive load under the voltage sag condition. The simulation and experimental results are carried out to verify the effectiveness of the proposed algorithm.

The track record of Mesozoic birds: evidence and implications

Abstract: The occurrence, systematics, palaeobiological and evolutionary significance of Mesozoic bird and birdlike tracks are reviewed in the light of recent new discoveries in East Asia, Africa and North America. The most abundant footprint evidence currently comes from Lower Cretaceous deposits of East Asia and North America, where there is now a substantial track record for shorebirds. However, there is also a significant record of pre-Cretaceous bird-like tracks. The Cretaceous Jindong Formation of South Korea has recently yielded over 30 localities and stratigraphic levels, tripling the previous record worldwide and providing evidence of hitherto unknown large waders: Jindongornipes kimi ichnogen. et ichnosp. nov. Like other previously named ichnotaxa, this bird track type probably represents a charadriiform species. It is included with Ignotornis and Koreanaornis in the new ichnofamily Ignotornidae. Lower Cretaceous bird tracks are abundant, typically show high densities (100-300 tracks m 2 ) and often occur in association with invertebrate traces, inferred to have been made by the organisms on which the birds were feeding. Such track evidence suggests that waterbird communities were well-established by the end of the Early Cretaceous. This is about 30 Ma before the purported waterbird radiation inferred from Upper Cretaceous avian skeletal remains, but is consistent with hypotheses that suggest an ancestral shorebird stock. Bird and bird-like tracks from the Jurassic and Late Cretaceous are variable in morphology, still poorly understood, and sometimes attributed to small coelurosaurian dinosaurs. However, current evidence suggests that the Jurassic aviform ichnogenus Trisauropodiscus may be of avian origin. It is sufficiently distinct from typical grallatorid (coelurosaurian) tracks to warrant recognition of a new ichnofamily (Trisauropodiscidae), which includes the newly described ichnospecies Trisauropodiscus moabensis from North America. Bird and bird-like tracks from both the Jurassic and Cretaceous are shown to be much more abundant and distinctive than previously supposed. Moreover, they add significantly to our understanding of early avian evolution and palaeoecology, and provide insights into the timing of events in avian evolution.

Robust Lane Detection Based On Convolutional Neural Network and Random Sample Consensus

Abstract: In this paper, we introduce a robust lane detection method based on the combined convolutional neural network (CNN) with random sample consensus (RANSAC) algorithm. At first, we calculate edges in an image using a hat shape kernel and then detect lanes using the CNN combined with the RANSAC. If the road scene is simple, we can easily detect the lane by using the RANSAC algorithm only. But if the road scene is complex and includes roadside trees, fence, or intersection etc., then it is hard to detect lanes robustly because of noisy edges. To alleviate that problem, we use CNN in the lane detection before and after applying the RANSAC algorithm. In training process of CNN, input data consist of edge images in a region of interest (ROI) and target data become the images that have only drawn real white color lane in black background. The CNN structure consists of 8 layers with 3 convolutional layers, 2 subsampling layers and multi-layer perceptron (MLP) including 3 fully-connected layers. Convolutional and subsampling layers are hierarchically arranged and their arrangement represents a deep structure in deep learning. As a result, proposed lane detection algorithm successfully eliminates noise lines and the performance is found to be better than other formal line detection algorithms such as RANSAC and hough transform.

S052: a comparison of robot-assisted, laparoscopic, and open surgery in the treatment of rectal cancer

Abstract: In recent years, robot-assisted surgery using the da Vinci System® has been proposed as an alternative to traditional open or laparoscopic procedures. The aim of this study was to compare the short-term outcomes for open, laparoscopic, and robot-assisted rectal resection for cancer. Two hundred sixty-three patients with rectal cancer who underwent curative resection between 2007 and 2009 were included. Patients were classified into an open surgery group (OS, n = 88), a laparoscopic surgery group (LAP, n = 123), and a robot-assisted group (RAP, n = 52). Data analyzed include operating time, length of recovery, methods of specimen extraction, quality of total mesorectal excision, and morbidity. The mean operating time was 233.8 ± 59.2 min for the OS group, 158.1 ± 49.2 min for the LAP group, and 232.6 ± 52.4 min for the RAP group (p < 0.001). Patients from the LAP and RAP groups recovered significantly faster than did those from the OS group (p < 0.05). The proportion of operations performed through a natural orifice (intracorporeal anastomosis with transanal or transvaginal retrieval of specimens) was significantly higher in the RAP group (p < 0.001). The specimen quality—with a distal resection margin, harvested lymph nodes, and circumferential margin—did not differ among the three groups. The overall complication rates were 20.5, 12.2, and 19.2% in the OS, LAP, and RAP groups, respectively (p = 0.229). RAP and LAP reproduce the equivalent short-term results of standard OS while providing the advantages of minimal access. For the experienced laparoscopic colorectal oncologist, use of the da Vinci robot resulted in no significant short-term clinical benefit over the conventional laparoscopic approach.