• Journal of Ocean Engineering and Technology
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• v.17 no.2
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• pp.54-59
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• 2003

The characteristics of the parameters for the probability distribution of fatigue crack growth life, using the non-Gaussian random process simulation method is investigated. In this paper, the material resistance to fatigue crack growth is treated as a spatial random process, which varies randomly on the crack surface. Using the previous experimental data, the crack length equals the number of cycle curves that are simulated. The results are obtained for constant stress intensity factor range conditions with stress ratios of R=0.2, three specimen thickness of 6, 12 and 18mm, and the four stress intensity level. The probability distribution function of fatigue crack growth life seems to follow the 3-parameter Wiubull,, showing a slight dependence on specimen thickness and stress intensity level. The shape parameter, $\alpha$, does not show the dependency of thickness and stress intensity level, but the scale parameter, $\beta$, and location parameter, ${\gamma}$, are decreased by increasing the specimen thickness and stress intensity level. The slope for the stress intensity level is larger than the specimen thickness.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2002.10a
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• pp.301-306
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• 2002

The characteristics of parameters for the probability distribution of fatigue crack growth lives by the non-Gaussian random process simulation method is investigated. In this paper, the material resistance to fatigue crack growth is treated as a spatial random process, which varies randomly on the crack surface. Using the previous experimental data, the crack length - the number of cycles curves are simulated. The results are obtained for constant stress intensity factor range conditions with stress ratio of R=0.2, three specimen thickness of 6, 12 and 18mm, and the four stress intensity level. The probability distribution function of fatigue crack growth lives seems to follow the 3-parameter Wiubull and shows a slight dependence on specimen thickness and stress intensity level. The shape parameter, ${\alpha}$, does not show the dependency of thickness and stress intensity level, but the scale parameter, ${\beta}$, and location parameter, ${\upsilon}$, are decreased by increasing the specimen thickness and stress intensity level. The slope for the stress intensity level is larger than the specimen thickness.

• Physical Therapy Korea
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• v.27 no.2
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• pp.102-110
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• 2020

Background: There is an opinion that improper postures of the head and cervical spine are associated with temporomandibular joint (TMJ) disorders (TMDs). Objects: The aim of this study was to investigate the proportions among the cervical kyphotic angle, physical symptoms including the pain intensity level of the TMJ, and severity of TMD disability in patients diagnosed with TMD. Methods: Sixty-two subjects participated in the study. The evaluation tools included measurements of the cervical kyphotic angle based on the Ishihara index, pressure pain threshold (PPT) on the TMJ, maximal mouth opening (MMO) without pain, current pain intensity level of the TMJ measured using the Quadruple Visual Analogue Scale (QVAS), Korean TMD (KTMD) disability index, KTMD Symptom Frequency/Intensity Scales (SFS/SIS), and Korean Headache Impact Test-6. Correlation analysis was conducted to investigate the correlations between the cervical kyphotic angle and parameters related to TMJ symptoms. Results: Variables that were significantly correlated with the cervical kyphotic angle were the PPT around the TMJ (r = 0.259, p < 0.05), current pain intensity level of the TMJ based on the QVAS (r = -0.601, p< 0.01), and usual pain intensity level based on the SIS (r = -0.379, p < 0.01). The level of TMD functional disability was significantly correlated with the degree of headache (r = 0.551, p < 0.01), level of PPT of the TMJ (r = -0.383, p < 0.01), pain-free MMO (r = -0.515, p < 0.01), pain intensity level of the TMJ based on the QVAS (r = 0.393, p < 0.01), TMD symptom frequency (r = 0.739, p < 0.01), usual pain intensity of the TMJ (r = 0.624, p < 0.01), and most severe pain intensity of the TMJ (r = 0.757, p < 0.01). Conclusion: There is a positive correlation between the cervical kyphotic angle and PPT and a negative correlation between the current and usual pain intensity levels of the TMJ. The cervical kyphotic angle was a predictor of the pain level, tenderness threshold, and intensity of pain in the TMJ.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.12 no.4
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• pp.1760-1778
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• 2018

For image segmentation with intensity inhomogeneity, many region-based level set methods have been proposed. Some of them however can't get the relatively ideal segmentation results under the severe intensity inhomogeneity and weak edges, and without use of the image gradient information. To improve that, we propose a new level set method combined with local direction gradient in this paper. Firstly, based on two assumptions on intensity inhomogeneity to images, the relationships between segmentation objects and image gradients to local minimum and maximum around a pixel are presented, from which a new pixel classification method based on weight of Euclidian distance is introduced. Secondly, to implement the model, variational level set method combined with image spatial neighborhood information is used, which enhances the anti-noise capacity of the proposed gradient information based model. Thirdly, a new diffusion process with an edge indicator function is incorporated into the level set function to classify the pixels in homogeneous regions of the same segmentation object, and also to make the proposed method more insensitive to initial contours and stable numerical implementation. To verify our proposed method, different testing images including synthetic images, magnetic resonance imaging (MRI) and real-world images are introduced. The image segmentation results demonstrate that our method can deal with the relatively severe intensity inhomogeneity and obtain the comparatively ideal segmentation results efficiently.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.21 no.9
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• pp.787-797
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• 2011

The noise in a vehicle is an important factor for customers purchasing a car. Particularly, reduction of the noise that is generated from HVAC(heating, ventilation and air conditioning) is very important since it has considerable effects on interior noise. In general, identification of noise source is crucial to reduce noise level. The complex acoustic intensity method is widely used to obtain the accurate measurement and identification of noise source. Therefore, in the previous study, noise source of HVAC was identified through experimental approach using the complex acoustic intensity method. In this study, we are intended to confirm reduced level of noise by comparing the result between before and after modification of cam curve that is based on identified noise source of HVAC. It is found out that noise source of HVAC are motor and cam area using the complex acoustic intensity method in the previous study. We performed experiments to compare noise level between before and after modification of cam curve. Especially, it can be seen that complex acoustic intensity method using both active and reactive intensity is vital in devising a strategy for comparison to noise level. Also, the vector flow of acoustic intensity was investigated to identify sound intensity distributions and energy flow in the near field of HVAC.

• The Journal of Korean Physical Therapy
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• v.32 no.5
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• pp.307-311
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• 2020

Purpose: This study examined the effects of changes in the intensity of Functional Electrical Stimulation (FES) on CorticoMuscular Coherence (CMC) during action observation. This paper presents a neurophysiological basis for the effective intensity of FES. Methods: Twenty-seven healthy volunteers were asked to observed a video with FES. The FES was provided with a sensory stimulation level, nerve stimulation level, and motor stimulation level. Simultaneously, an electroencephalogram (EEG) of the sensorimotor cortex and electromyogram (EMG) from the wrist extensor muscle were recorded. The peak CMC and average CMC were analyzed to compare the differences caused by the FES intensity. Results: The peak CMC showed a significant increase in the alpha band during motor stimulation (p<0.05). The average CMC showed a significant increase in the beta band during motor stimulation (p<0.05). Conclusion: The intensity of FES, which causes actual movement, increased the CMC during action observation. These results show that the intensity of the FES can affect the functional connection between the sensorimotor cortex and muscle.

• Journal of Biomedical Engineering Research
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• v.32 no.1
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• pp.55-60
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• 2011

Although sound intensity is considered as one of important factors in auditory processing, its neural mechanism in auditory neurons with limited dynamic range of firing rates is still unclear. In this study, we examined the effect of sound intensity adaptation on the change of glucose metabolism in a rat brain using [F-18] micro positron emission tomography (PET) neuroimaging technique. In the experiment, broadband white noise sound was given for 30 minutes after the [F-18]FDG injection in order to explore the functional adaptation of rat brain into the sound intensity levels. Nine rats were scanned with four different sound intensity levels: 40 dB, 60 dB, 80 dB, 100 dB sound pressure level (SPL) for four weeks. When glucose uptake during the adaptation of a high intensity sound level (100 dB SPL) was compared with that during adaptation to a low intensity level (40 dB SPL) in the experiment, the former induced a greater uptake at bilateral cochlear nucleus, superior olivary complexes and inferior colliculi in the auditory pathway. Expectedly, the metabolic activity in those areas linearly increased as the sound intensity level increased. In contrast, significant decrease interestingly occurred in the bilateral auditory cortices: The activities of auditory cortex proportionally decreased with higher sound intensities. It may reflect that the auditory cortex actively down-regulates neural activities when the sound gets louder.

• Journal of the Korean Applied Science and Technology
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• v.31 no.3
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• pp.492-499
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• 2014

The objectives of this study was to examine experimentally the microexplosion phenomena of single droplet W/O(water-in-oil) type emulsified fuel. Also, measured the combustion characteristics of single droplet emulsified fuel for microexplosion phenomena in atmospheric pressure condition. The larger quantity of adding water makes microexplosion phenomenon with higher intensity of sound level, because larger water droplet has better coalescence for emulsified fuel. The small quantity of adding water makes puffing with lower sound level intensity. In latter period of extinction, large size droplet of the emulsified fuel breaks down rapidly to small size droplet, and microexplosion phenomenon occurs with multi step combustion.

• Journal of the Korean Institute of Landscape Architecture
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• v.32 no.4
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• pp.1-6
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• 2004

This study was carried out to investigate the effects of light intensities on the growth and net photosynthesis of Piper kauzura under different shading levels : 0％, 50％, 70％ and 90％ of sunlight. Mortality rate was lowest under a 70％ shading level but 0％ and 90％ shading levels were about 46％ and 53％ each respectively. Plant height was shorter and leaf size was smaller and yellowish under a 0％ shading level but increased when light intensity was decreased. However, under a 90％ shading level, growth of Piper kauzura was inferior to other treatments. Top fresh weight was about 11.24g under a 50％ shading level and about two times higher than that observed in about 6.6g under a 90％ shading level. Root fresh weight was about 7.7g under a 0％ shading level and was about two times higher than that showed in about 3.84g and 3.64g under 90％ and 70％ respectively. Total chlorophyll content and chlorophyll a/b rate were increased when light intensity was decreased. Net Photosynthesis achieved the highest under a 70％ shading level and maximum photosynthetic photon flux density was 150 molㆍm/sup -2/ㆍs/sup -1/. Therefore, growth of Piper kauzura was good under 50∼70％ shading, Meaning that it is an indoor plant that could be highly utilized.

• Publications of The Korean Astronomical Society
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• v.30 no.2
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• pp.47-51
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• 2015

Ground Level Enhancements (GLEs) in cosmic ray intensity observed during the period of 1997-2012 have been studied with energetic solar features and disturbances in solar wind plasma parameters and it is seen that all the GLEs have been found to be associated with coronal mass ejections, hard X-ray solar flares and solar radio bursts. All the GLEs have also been found to be associated with sudden jumps in solar proton flux of energy of ${\geq}60Mev$. A positive correlation with correlation coefficient of 0.48 has been found between the maximum percentage intensity (Imax%) of Ground Level Enhancements and the peak value of solar proton flux of energy (${\geq}60Mev$). All the Ground Level Enhancements have been found to be associated with jumps in solar wind plasma velocity (JSWV) events. A positive correlation with correlation coefficient of 0.43 has been found between the maximum percentage intensity (Imax %) of Ground Level Enhancements and the peak value of solar wind plasma velocity of associated (JSWV) events. All the Ground Level Enhancements have been found to be associated with jumps in solar wind plasma pressure (JSWP) events. A positive correlation with correlation coefficient of 0.67 has been found between the maximum percentage intensity (Imax %) of Ground Level Enhancements and the peak value of solar wind plasma pressure of associated (JSWP) events and of 0.68 between the maximum percentage intensity (Imax %) of Ground Level Enhancements and the magnitude of the jump in solar wind plasma pressure of associated (JSWP) events.