• Tuberculosis and Respiratory Diseases
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• v.71 no.4
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• pp.271-277
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• 2011

Background: A chronic obstructive pulmonary disease (COPD) assessment test (CAT) has recently been developed as a short and simple method for assessing the quality of life in COPD patients. The object of this study was to assess the usefulness of the Korean version of the CAT for assessing COPD patients in an outpatient clinic. Methods: The study included 60 COPD patients in a stable state from an outpatient clinic. The authors investigated the frequency of acute exacerbation during aprevious year through reviewing medical records. We evaluated the spirometry test, a 6-min walk distance test, and obtained the MMRC dyspnea scale, the Korean version of the CAT, and the BODE index at the time of visit. To assess the usefulness of the CAT, correlations between the CAT and other methods were evaluated. Results: The mean age of patients was $68.3{\pm}8.6$ years and 95% of patients were male. There was a significant correlation between the CAT score and $FEV_1%$ (r=-0.323, p=0.012), the frequency of acute exacerbation (r=0.292, p=0.024), the MMRC dyspnea scale (r=0.554, p<0.001), the BODE index (r=0.380, p=0.003), and 6 MWD (r=-0.372, p=0.004). The mean CAT score increased according to the GOLD stage (stage 1, $10.7{\pm}4.5$; stage 2, $13.1{\pm}7.9$; stage 3, $16.3{\pm}6.2$; stage 4, $16.5{\pm}14.8$; p=0.746). Conclusion: The CAT was shown to be useful for the assessment of COPD severity. Therefore, the CAT is an easily applied and simple method for assessing COPD severity in an outpatient clinic.

• Proceedings of the Korea Crystallographic Association Conference
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• 2002.11a
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• pp.12-12
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• 2002

Lanthanum manganites have been extensively studied for the application to magnetic devices since the colossal magnetoresistance of these compounds has been observed [1]. The critical temperatures, Tc, of manganites La/sub 0.7/Ca/sub 0.3-x/Ba/sub x/MnO₃ increased as the content of Ba increased except the abrupt jump near the critical concentration. The step like behavior of the critical temperature for a similar compound has been known to be related to the structural phase transition [2]. To understand the step like behavior of Tc, the EXAFS technique is applied to the La/sub 0.7/Ca/sub 0.3-x/Ba/sub x/MnO₃ compound system. The ordering between the manganese and oxygen was examined by this method. The EXAFS analysis shows that the coordination numbers were not changed before and after the phase transition, the bonding distance between manganese and oxygen is about 1.94 ± 0.02 Å, which is consistent with other work [3] and the Debye waller parameters were about σ²= 0.0037 ± 0.0005 Ų for x=0.0 and x=3.0, respectively. The value of Debye-Waller parameter for x=0.09 is about σ² = 0.0050 ± 0.0005 Ų in about phase transition concentration. Based on the Debye-Waller parameters, it is shown that the ordering between manganese and oxygen is significantly reduced near the phase transition concentration.

• Structural Engineering and Mechanics
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• v.67 no.2
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• pp.185-206
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• 2018

This paper studies the non-axisymmetric 3D problem on the dynamics of the moving load acting in the interior of the hollow cylinder surrounded with elastic medium and this study is made by utilizing the exact equations of elastodynamics. It is assumed that in the interior of the cylinder the point located with respect to the cylinder axis moving forces act and the distribution of these forces is non-axisymmetric and is located within a certain central angle. The solution to the problem is based on employing the moving coordinate method, on the Fourier transform with respect to the spatial coordinate indicated by the distance of the point on the cylinder axis from the point at which the moving load acts, and on the Fourier series presentation of the Fourier transforms of the sought values. Numerical results on the critical moving velocity and on the distribution of the interface normal and shear stresses are presented and discussed. In particular, it is established that the non-axisymmetricity of the moving load can decrease significantly the values of the critical velocity.

• Progress in Superconductivity and Cryogenics
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• v.9 no.3
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• pp.1-4
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• 2007

The current profiles in a coated conductor with transport current were calculated using an iterative inversion method from the data of the magnetic flux density profiles measured. The applied current was increased from 0 to 60 A by 10A step and decreased down to -60A by 20A step. The magnetic flux profiles were measured at a distance of 400 mm above the surface of the coated conductor using a scanning hall probe method. The current profiles calculated were very different from the Bean model: current density profile is not a constant in the critical region. However the aspect of the change of the current and magnetic flux density profiles in the case of decreasing applied current are similar to the theoretical calculations in Brandt's paper.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.15 no.6
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• pp.457-462
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• 2022

Recently, a variety of cultural life using drones as an entertainment tool has been created, and in order to realize this, more and more users are using drones with good performance enough to invade the no-flight zone. Drones for satisfying entertainment activities must have long flight times and be able to fly long distances, which can often cause great damage by invading no-flight zones or causing unwanted flight crashes. In this study, in order to solve this problem, a no-flight zone is set with GCS(Ground Control System), and when flying at a critical speed of 10km/h or less, the drone is safely operated by not entering the critical distance 10m away from the no-flight zone, and the critical speed A method was proposed to prevent the drone from entering the no-flight zone by allowing the drone to self-drop by GCS control when it flies beyond the threshold and enters the critical distance. As a result of a total of 44 repeated experiments in a specific experimental area with the proposed method, the drone safely self-dropped except for the case where it crossed the restricted area once or twice. It was found to be an appropriate way to prevent this.

• Transactions of the Korean Society of Mechanical Engineers
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• v.17 no.11
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• pp.2762-2772
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• 1993

The paper deals with the flutter of a cantilevered beam subjected to a rocket thrust generated by a solid rocket motor. It is saaumed that the rocket thrust is to be a constant follower thrust, and produced by the installation of a solid rocket motor to the tip end of the cantilevered beam. The rocket motor is considered to be a rigid body having finite sizes, but not a mass point as it has been assumed so far. Governing equations are derived through the extended Hamilton's principle, and finite element method is applied to obtain the theoretical prediction for critical follower thrust. The maximum follower thrust is also calculated through the change of shear deformation parameter of the beam in the numerical simulation. The theoretical prediction for flutter or stability is verified by experiment. The experimental results show that critical follower thrust in theory agrees well with the experimental value taking account of the magnitude, rotary inertia of the rocket motor and the distance from the tip end of the beam to the center of gravity of the rocket motor.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2009.01a
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• pp.390-395
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• 2009

The robustness of audio fingerprinting system in a noisy environment is a principal challenge in the area of content-based audio retrieval. The selected feature for the audio fingerprints must be robust in a noisy environment and the computational complexity of the searching algorithm must be low enough to be executed in real-time. The audio fingerprint proposed by Philips uses expanded hash table lookup to compensate errors introduced by noise. The expanded hash table lookup increases the searching complexity by a factor of 33 times the degree of expansion defined by the hamming distance. We propose a new method to improve noise robustness of audio fingerprinting in noise environment using predominant pitch which reduces the bit error of created hash values. The sub-fingerprint of our approach method is computed in each time frames of audio. The time frame is transformed into the frequency domain using FFT. The obtained audio spectrum is divided into 33 critical bands. Finally, the 32-bit hash value is computed by difference of each bands of energy. And only store bits near predominant pitch. Predominant pitches are extracted in each time frames of audio. The extraction process consists of harmonic enhancement, harmonic summation and selecting a band among critical bands.

• Journal of the Society of Naval Architects of Korea
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• v.47 no.4
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• pp.573-579
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• 2010

The notch effects on the fatigue strength of welded joints are both stress concentration and fatigue strength reduction. In the notch stress approach, the notch effects are usually approximated by introducing weld-bead parameters for the local detailed weld joints. In this paper, well-known notch stress approaches - critical distance method, area method and fictitious rounding method are presented for the fatigue strength of cruciform joints. The estimated results of the present methods are applied to the experiments performed in this study and reported in the references. The results of the application show that the fatigue-life scatterness of the experimental data expressed in the nominal stress is significantly reduced by introducing the effective fatigue stress of the present study.

• Proceedings of the SAREK Conference
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• 2005.11a
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• pp.235-240
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• 2005

Recently urban utility plants in urban areas of Korea, such as energy supply systems, municipal waste incineration systems, sewage treatment systems and so on, have caused some critical troubles, for instance the insensitive response to the seasonal or daily variation of loads, the low system efficiency and inefficient use of energy because of the large-scale system located a great distance. Therefor the design method of optimal integrated system model of various urban utility plants proposed in this study suitably to the present situation of Korea. Also, the effect analysis for the introduction of compound utility plants was studied for a new town model on a 60,000 persons scale. As the results we found that the complex plant was superior to individual urban utility plant in side of the initial investment expenses, the operating cost and other reasons.

• Communications for Statistical Applications and Methods
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• v.29 no.3
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• pp.301-317
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• 2022

In this paper, we propose a change point detection procedure based on the modified information criterion in a generalized lambda distribution (GLD) model. Simulations are conducted to obtain empirical critical values of the proposed test statistic. We have also conducted simulations to evaluate the performance of the proposed methods comparing to the log-likelihood method in terms of power, coverage probability, and confidence sets. Our results indicate that, under various conditions, the proposed method modified information criterion (MIC) approach shows good finite sample properties. Furthermore, we propose a new goodness-of-fit testing procedure based on the energy distance to evaluate the asymptotic null distribution of our test statistic. Two real data applications are provided to illustrate the use of the proposed method.