• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.32 no.8
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• pp.20-28
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• 2004

For the prediction on the onset of oblique shock wave-induced vortex breakdown, computational studies on the Oblique Shock wave/Vortex Interaction (OSVI) are conducted and compared with both experimental results and analytic mode1. A Shock-stable numerical scheme, the Roe scheme with Mach number-based function (RoeM), and a two-equation eddy viscosity-transport approach arc used for three-dimensional turbulent flow computations. The computational configuration is identical to available experiment, and we attempt to ascertain the effect of parameters such as a vortex strength, streamwise velocity deficit, and shock strength at a freestream Mach number of 2.49. Numerical simulations using the k-w SST turbulence model and suitably modeled vortex profiles are able to accurately reproduce many fine features through a direct comparison with experimental observations. The present computational approach to determine the criterion on the onset of oblique shock wave-induced vortex breakdown is found to be in good agreement with both the experimental result and the analytic prediction.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.27 no.4
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• pp.334-345
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• 2005

The purpose of this study was to compare the postoperative stability and relapse according to 2 different fixation methods after bilateral sagittal split ramus osteotomies in mandibular prognathic patients. Tweenty one patients with Class III dental and skeletal malocclusion who were treated with bilateral sagittal split ramus osteotomy were selected for this retrospective study. We classfied the patients into two groups according to the fixation methods of bony segments after osteotomies. Group W (n = 10) had the bone segments fixed with nonrigid wire and Group S (n = 11) had bicortical screws inserted in the gonial area through a transcutaneous approach. Cephalometric radiographs were taken preoperatively, immediate postoperatively and more than six months postoperatively in each patient. After tracing the cephalometric radiographs, various parameters were measured. Before surgery, both groups were balanced with respect to linear and angular measurements of craniofacial morphology. Mean posterior sagittal setback amounts of the mandibular symphysis was 8.6 mm in the wire group and 6.79 mm in the rigid group, Six months postoperatively, the wire group had 33.1% relapse of the mandibular symphysis and 22.8% in the rigid group relapse. Both groups experienced changes in the orientation and configuration of the mandible. It is thought that Rigid screw fixation is a more stable method than nonrigid wire fixation for maintaining mandibular setback after sagittal split ramus osteotomy.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.7 no.11
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• pp.2577-2596
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• 2013

In this paper, we present an Energy-Aware Self-Stabilizing Distributed Clustering protocol based on message-passing model for Ad Hoc networks. The latter does not require any initialization. Starting from an arbitrary configuration, the network converges to a stable state in a finite time. Our contribution is twofold. We firstly give the formal proof that the stabilization is reached after at most n+2 transitions and requires at most $n{\times}log(2n+{\kappa}+3)$ memory space, where n is the number of network nodes and ${\kappa}$ represents the maximum hops number in the clusters. Furthermore, using the OMNeT++ simulator, we perform an evaluation of our approach. Secondly, we propose an adaptation of our solution in the context of Wireless Sensor Networks (WSNs) with energy constraint. We notably show that our protocol can be easily used for constructing clusters according to multiple criteria in the election of cluster-heads, such as nodes' identity, residual energy or degree. We give a comparison under the different election metrics by evaluating their communication cost and energy consumption. Simulation results show that in terms of number of exchanged messages and energy consumption, it is better to use the Highest-ID metric for electing CHs.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.32 no.9
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• pp.315-324
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• 1983

Dynamic stability problems have been experienced with a generator connected to an infinite bus through a long transmission line. Nuclear turbine-generator units #1 and #2 at the Winsconsin Electric Power Point Baech Station were found to be dynamically unstable when one unit is isolated on one of the lines to Milwaukee or when two units are isolaed on the lines to milwaukee. Power System Stabilizers(PSS) were applied to the excitation system to provide stable operation under these conditions. Suitable settings for the PSS were predetetermined analytically by computer method and root licus analysis of an equivalent single machine-infinite bus configuration. This procedure allows graphical approach to the design of power stabilizers and serves as assynthesis procedure when the design constraints are relaxed so the the speed stabilizer is required ro provide animprovement in system damping. A simplified model of the complete exciter generator system is shown to be adequate for this type of analysis.

• Journal of the Korea Computer Graphics Society
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• v.21 no.4
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• pp.19-26
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• 2015

This paper presents a method for optimizing a carrying pose of human body for a given object. The inputs are articulated human body model and and arbitrary-shaped object. We assume that the object is big and heavy, so that both arms should be used to carry it. Unlike small and light objects, big and heaby objects can be hold by only a small range of body poses while keeping a physical statbility. We first introduce an algorithm that evaluates a physical stability of a given human body pose and object state (position and orientation). Then, we define a configuration space and search the space for the most stable carrying pose by using the evaluation algorithm. Finally, to demonstrate the usability of our method, we present the results which each is experimented with different shaped objects and additional user conditions.

• Journal of Advanced Navigation Technology
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• v.17 no.6
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• pp.785-791
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• 2013

Recently, Elevator industry is pursuing new challenges to the model of the IT convergence. The core of the convergence technologies may be the effective control and maintenance of the machine. However, because current elevator management model provides each specific model for his elevator, the management models have a variety of heterogeneous configuration so that it makes management companies to manage the elevators with many overhead. In this paper, we propose the integration framework for the various elevator models. We use proposed system based on the Android framework that is rapidly expanding technology in the embedded environment, and we propose design approach for the integration of variety of lift devices so that it provide a more efficient and stable service environment. In this way, we could integrate various device models of an elevator for the management and maintenance effectively and quickly.

• Korean Journal of Remote Sensing
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• v.38 no.6_1
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• pp.1505-1514
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• 2022

Image matching is a crucial preprocessing step for effective utilization of multi-temporal and multi-sensor very high resolution (VHR) satellite images. Deep learning (DL) method which is attracting widespread interest has proven to be an efficient approach to measure the similarity between image pairs in quick and accurate manner by extracting complex and detailed features from satellite images. However, Image matching of VHR satellite images remains challenging due to limitations of DL models in which the results are depending on the quantity and quality of training dataset, as well as the difficulty of creating training dataset with VHR satellite images. Therefore, this study examines the feasibility of DL-based method in matching pair extraction which is the most time-consuming process during image registration. This paper also aims to analyze factors that affect the accuracy based on the configuration of training dataset, when developing training dataset from existing multi-sensor VHR image database with bias for DL-based image matching. For this purpose, the generated training dataset were composed of correct matching pairs and incorrect matching pairs by assigning true and false labels to image pairs extracted using a grid-based Scale Invariant Feature Transform (SIFT) algorithm for a total of 12 multi-temporal and multi-sensor VHR images. The Siamese convolutional neural network (SCNN), proposed for matching pair extraction on constructed training dataset, proceeds with model learning and measures similarities by passing two images in parallel to the two identical convolutional neural network structures. The results from this study confirm that data acquired from VHR satellite image database can be used as DL training dataset and indicate the potential to improve efficiency of the matching process by appropriate configuration of multi-sensor images. DL-based image matching techniques using multi-sensor VHR satellite images are expected to replace existing manual-based feature extraction methods based on its stable performance, thus further develop into an integrated DL-based image registration framework.