• Journal of computational fluids engineering
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• v.15 no.1
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• pp.37-45
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• 2010

Deforming mesh should be used when bodies are deforming or moving relative to each other due to the presence of aerodynamic forces and moments. Also, the flow solver for such a flow problem should satisfy the geometric conservation law to ensure the accuracy of the solutions. In this paper, a RANS(Reynolds Averaged Navier-Stokes) solver including automatic mesh capability using TFI(Transfinite Interpolation) method and GCL is developed and applied to flows induced by oscillating wings with given frequencies. The computations are performed both on deforming meshes and on rigid meshes. The computational results are compared with experimental data, which shows a good agreement.

• Journal of the Korean Society for Precision Engineering
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• v.15 no.5
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• pp.100-109
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• 1998

In order to increase productivity through unmanned machining in CNC milling process, in-process tool fracture detection is required. In this paper, a new algorithm for tool fracture detection using cutting load variations was developed. For this purpose, developed were tool condition vector which is dimensionless indicator of cutting load and tool fracture index (TFI) which represents magnitude of tool fracture. Through cutting force simulation, tool fracture index was shown to be independent of tool run-outs and cutting condition variations. Using tool fracture index, the ratio of the tool fracture to feed per tooth could be indentified.

• Journal of computational fluids engineering
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• v.12 no.4
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• pp.28-37
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• 2007

In this study, a multi-block structured grid deformation code based on a hybrid of a transfinite interpolation algorithm and spring analogy was developed. The configuration was modeled by a Bezier surface. A combination of the spring analogy for block vertices and the transfinite interpolation for interior grid points helps to increase the robustness and makes it suitable for distributed computing. An elliptic smoothing operator was applied to the block faces with sub-faces in order to maintain the grid smoothness and skewness. The capability of this code was demonstrated on a range of simple and complex configurations including an airfoil and a wing-body configuration.

• International Journal of Contents
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• v.1 no.2
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• pp.26-30
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• 2005

According to the fast growth of information on the Internet, it is becoming increasingly difficult to find and organize useful information. To reduce information overload, it needs to exploit automatic text classification for handling enormous documents. Support Vector Machine (SVM) is a model that is calculated as a weighted sum of kernel function outputs. This paper describes a document classifier for web documents in the fields of Information Technology and uses SVM to learn a model, which is constructed from the training sets and its representative terms. The basic idea is to exploit the representative terms meaning distribution in coherent thematic texts of each category by simple statistics methods. Vector-space model is applied to represent documents in the categories by using feature selection scheme based on TFiDF. We apply a category factor which represents effects in category of any term to the feature selection. Experiments show the results of categorization and the correlation of vector length.

• Clinical and Experimental Pediatrics
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• v.45 no.2
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• pp.192-198
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• 2002

Purpose : It is important to select and use kinds of Inhaler appropriate to the age of the patient and severity of symptoms. Several kinds of Inhaler have been developed and recommended according to each inhaler's resistance and usage method. We evaluated the usable age of 4 inhalers (turbulent flow inhalers, multi unit dose inhalers, breath actuated MDI, and autohalers) by measuring peak inspiratory flow(PIF) using $In-Check^{(TM)}$ Inspiratory Flow Meter. Methods : Ninety three patients aged from 3 to 7 years(mean $57{\pm}12.9$ mo.) who had admitted to CHA hospital from July 2000 to April 2001 were enrolled. Study patients were divided into 4 groups according to age : 3-4 years of age(group A, n=31), 4-5 years of age(group B, n=32), 5-6 years of age(group C, n=18), and 6-7 years of age(group D, n=12). Results : Out of total 93 patients, 23(71%), 27(84%), 17(94%) patients of each group A, B, C and all 12 patients of group D could use the 4 types of inhaler through adequated education. In all four groups, height, body weight and age were significantly correlated(P<0.05). Usable age, height and weight of children who can use turbulent flow inhaler(TFI) were each 8 year 7 month old, 144 cm, 32.0 kg, and those of multi unit dose inhaler(MUD) were 2 year 10 month old, 92 cm, 12.0 kg. Also that of breath-actuated MDI were 1 yr 8 months, 83 cm, 8.5 kg and that of autohaler were 2 yr 8 months, 91 cm, 11.0 kg Conclusion : We concluded that the ability to use inhalers correlated with height, weight and age of the patients. Multi unit dose inhalers, Breath actuated MDI and Autohaler are useful after 3 years of age through adequate education.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.11
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• pp.394-401
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• 2019

This study examined the effects of restricted feeding on the growth performance, carcass characteristics, and economic efficiency of finishing pigs for 27 days. A total of 24 finishing pigs (Landrace×Yorkshire×Duroc, average initial body weight of 81.52±1.11 kg) were allotted randomly to two treatments with 12 replicates (one pig per replicate). The experimental treatments were ad libitum feeding (AF), and restricted feeding (RF) with a 10% increase in offered feed than the day before if required. The results showed that the average daily feed intake (ADFI; p<0.001) of the pigs were improved in the RF treatment, but there were no changes in the average daily gain and weight gain to feed intake ratio (G:F). There were no significant differences in carcass weight and backfat thickness. In addition, the total pork price per pig was not affected by RF. Although total feed intake (TFI) and total feed intake cost (TFC) were significantly lower in the RF pigs (p<0.001), the feed cost per 1 kg weight gain (FCG) was similar regardless of the treatments. In conclusion, the RF method may decrease the feed cost due to a lower TFI and TFC.

• Journal of the Korea Institute of Military Science and Technology
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• v.21 no.2
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• pp.133-140
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• 2018

In electronic warfare(EW), low probability of intercept(LPI) radar signal is a survival technique. Accordingly, identification techniques of the LPI radar waveform have became significant recently. In this paper, classification and extracting parameters techniques for 7 intrapulse modulated radar signals are introduced. We propose a technique of classifying intrapulse modulated radar signals using Convolutional Neural Network(CNN). The time-frequency image(TFI) obtained from Choi-William Distribution(CWD) is used as the input of CNN without extracting the extra feature of each intrapulse modulated radar signals. In addition a method to extract the intrapulse radar modulation parameters using binary image processing is introduced. We demonstrate the performance of the proposed intrapulse radar waveform identification system. Simulation results show that the classification system achieves a overall correct classification success rate of 90 % or better at SNR = -6 dB and the parameter extraction system has an overall error of less than 10 % at SNR of less than -4 dB.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.30 no.7 s.250
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• pp.741-749
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• 2006

For last couple of decades, uses of TFI-LCDs have been expanded to many FPD(Flat Panel Display) applications including mobile displays, desktop monitors and TVs. Furthermore, there has been growing demand for increasingly larger LCD TVs. In order to meet this demand as well as to improve productivity, LCD manufactures have continued to install larger-generation display fabrication facilities which are capable of producing more panels and larger displays per mother glass(substrate). As the size of mother glass becomes larger, a robot required to handle the glass becomes bigger accordingly, and its end effectors(arms) are extended to match the glass size. With this configuration, a considerable static deflection occurs at the end of the robot arms. In order to stack maximum number of mother glasses on a given footprint, the static deflection should be compensated. This paper presents a novel static deflection compensation algorithm. This algorithm requires neither measurement instrument nor additional vertical axis on the robot. It is realized by robot controller software. The forward and inverse kinematics considering compensation always guarantees a unique solution, so the proposed algorithm can be applied to an arbitrary robot position. The algorithm reduced static deflection by 40% in stationary robot state experiment. It also improved vertical path accuracy up to 60% when the arm was running at its maximum speed. This algorithm has been commercialized and successfully applied to a seventh-generation LCD glass-handling robot.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.3C
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• pp.311-321
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• 2009

This paper proposes an efficient frequency offset estimation algorithm for MB-OFDM based UWB systems. The time-frequency interleaving in MB-OFDM extends the time-interval between two transmitted OFDM symbols in the same sub-band. The extended time-interval causes not only the degradation of the system performance by reducing frequency offset estimation range, but also the increase of the hardware complexity by requiring the larger number of storing samples. The proposed estimation algorithm expands the estimation range by applying the proposed sign detection scheme. Simulation results show that the estimation range is increased above 30 ppm compared with a conventional auto-correlation based scheme. The estimation is performed on only one sub-band, and the frequency offsets of the others are calculated by relation to center frequency. This way reduced the number of the storing samples by about l/3. The frequency offset estimator with the proposed algorithm was designed into the architecture which minimizes hardware overhead by time-sharing operators and memory units, and which was synthesized to gate-level circuits using $0.13{\mu}m$ CMOS technology, and the total gates were about 47K.

• Journal of the Korean Orthopaedic Association
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• v.56 no.3
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• pp.208-214
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• 2021

Purpose: Verifying a reliable predictor of the progression of vertebral deformity in patients with acute osteoporotic fractures of the lumbar spine may be useful. A qualitative analysis of the muscle near the spine was performed using magnetic resonance imaging (MRI), and its correlation with a spinal deformity was determined under the hypothesis that the causes of the kyphotic deformity are associated with muscle reduction in the multifidus and erector spinae. Materials and Methods: The study was performed in a retrospective manner using the electronic medical records of patients who presented to the author's institution between January 2007 and March 2018, and were diagnosed with an acute lumbar fracture. The fat infiltration rates of the multifidus and erector spinae were measured using MRI taken at the time of injury, and the mean value was defined as the total fat infiltration rate (TFI). Based on lateral radiographs of the lumbar spine at the one-year follow-up, the loss of height of the vertebral body, the kyphotic angle and the wedge angle were measured. The statistical significance was confirmed by calculating the Pearson correlation coefficient. Results: One hundred twenty-nine patients, of which 30 were male and 99 were female, were examined. The mean age was 71.28 years. The mean T-score was -3.53±0.79 g/cm², and the mean fat infiltration was 15.20%±11.99%. TFI was positively correlated with age (R=0.373, p<0.001), compression rate (R=0.369, p<0.001), and Cobb's angle (R=0.386, p<0.001) after a one year follow-up, but negatively correlated with the BMD score (R=-0.252, p=0.004). As the fracture progressed to the lower lumbar level, the compression rate (R=-0191, p=0.030) and wedge angle (R=-0.428, p<0.001) at the time of injury tended to decrease. Conclusion: In patients with osteoporotic vertebral fractures, the fat infiltration rate may be an important predictor of conservative treatment. The prognosis of patients with a high-fat infiltration rate should be explained during patient education, and the patients must be monitored closely through short-term outpatient follow-up.