• Journal of Industrial Technology
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• v.19
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• pp.269-278
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• 1999

When a variety of repeated loads are given, most steel structures failed in much lower level of loads than static failure loads. In addition, bridge always includes the internal defects or discontinuities. from these, fatigue cracks initiates and can lead to sudden failure. Thus, in this study, tensile specimens by the cover plate shapes were used as the test specimens. The fatigue test was performed by constant amplitude fatigue loading and beach mark. From the results of this study, each specimen's fatigue section was observed. in addition, stress intensity factor at crack tip was calculated by using the Green's function which applied to discontinuous section where causing stress concentration. Therefore, the fatigue life of structural detail was investigated by adopting the theories of fracture mechanics. each specimen's crack shape is a semi-elliptical surface crack or center crack sheet, stress gradient correction factor, Fg is the most subjective of all stress intensity correction factors and fatigue life should be predicted by previous proposed function and finite element analysis.

• Coupled systems mechanics
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• v.5 no.4
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• pp.315-327
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• 2016

Undergoing large volumetric changes upon incremental environmental stimulation, hydrogels are interesting materials which hold immense potentials for utilization in a wide array of applications in diverse industries. Owing to the large magnitudes of deformation it undergoes, swelling induced instability is a commonly observed sight in all types of gels. In this work, we investigate the instability of photo-thermal sensitive hydrogels, produced by impregnating light absorbing nano-particles into the polymer network of a temperature sensitive hydrogel, such as PNIPAM. Earlier works have shown that by using lights of different intensities, these hydrogels follow different swelling trends. We investigate the possibility of utilizing this fact for remote switching applications. The analysis is built on a thermodynamic framework of inhomogeneous large deformation of hydrogels and implemented via commercial finite element software, ABAQUS. Various examples of swelling induced instabilities, and its corresponding dependence on light intensity, will be investigated. We show that the instabilities that arise have their morphologies dependent on the light intensity.

• Journal of Navigation and Port Research
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• v.29 no.1 s.97
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• pp.113-118
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• 2005

We studied field observation and countermeasure about the effluent of sediment and nutrient materials on the Okinawa Ishigaki Coast according rainy season though this observation, we found out the analysis of outflow topography, intensity of rainfall and effects on the tide, the property of effluent materials ete. The sediment and nutrient concentration of the Okinawa Ishigaki coast are different on the regional sites according to vary with time variation of intensity of rainfall and the ebb and flow. We could confirm to vary with utilized waterways land area and distribution of surrounding vegetation.

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.1222-1227
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• 2003

Pitting wear is a dominant form of polyethylene surface damage in total knee replacements, and may originate from surface cracks that propagate under repeated tribological contact. In this study, stress intensity factors, $K_{I}$ and $K_{II}$, were calculated for a surface crack in a polyethylene - CoCr - bone system under the rolling and/or sliding contact pressures. Crack length and load location were considered in determination of probable crack propagation mechanisms and fracture modes. Positive $K_{I}$ values were obtained for shorter cracks in rolling contact and for all crack lengths when the sliding load was apart from the crack. $K_{II}$, was the greatest when the load was directly adjacent to the crack $(g/a={\pm}1)$. Sliding friction caused a substantial increase of both $K_{I}^{max}$ and $K_{II}^{max}$. The effective Mode I stress intensity factors, $K_{eff}$, were the greatest at $g/a={\pm}1$, showing the significance of high shear stresses generated by loads adjacent to surface cracks. Such behavior of $K_{eff}$ suggests mechanisms for surface pitting by which surface cracks may propagate along their original plane under repeated rolling or sliding contact.

• Phonetics and Speech Sciences
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• v.4 no.1
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• pp.49-54
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• 2012

Recent studies on acoustic correlates of stress in English compounds and English phrases have revealed the difference of changes in acoustic manifestation between English compounds and English phrases with different intonation patterns. However, little effort has been made to compare Korean compounds and Korean phrases in different intonational environments. Therefore, this study focuses on the analysis of acoustic characteristics of Korean compounds and Korean phrases produced in different intonational sentence patterns (Subject, Question, Clause-Final, and Statement-Final). Measurements of vowel duration, intensity (dB) and pitch (in semitones) were compared. The results of the experiment in which 30 native speakers of Korean pronounced Korean compounds and Korean phrases (obtained from $8{\times}30$ sentences) in controlled prosodic and intonational environments reveal clear patterns that distinguish Korean compounds from Korean phrases and support the evidence of acoustic salience for phrases. Duration differences turned out to be a significant cue to distinguish Korean compounds and Korean phrases in all but the Clause Final position. According to the size effect, duration ratio is the most reliable cue to distinguish Korean compounds and Korean phrases followed by the pitch differences between the first syllable and the second syllable and the intensity ratio. Implications for Korean and English intonation training were also discussed.

• Environmental Engineering Research
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• v.15 no.4
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• pp.191-195
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• 2010

This study was carried out to investigate the important factors relating to runoff and pollutant loads in a plot unit located in an agricultural area. Of the precipitation parameters, such as total precipitation, days since last rainfall (ADD, the rainfall was more than 10mm) and average rainfall intensity on runoff, the strongest effect was obtained due to total precipitation, but the rainfall intensity showed a slightly positive correlation. It was expected that both variables, i.e. total precipitation and rainfall intensity, would lead to the generation of greater runoff. In contrast, runoff was negatively correlated with ADD, which is understandable because more infiltration and less runoff would be expected after a long dry period. The TSS load varied greatly, between 75.6 and $5.18{\times}10^4g$, per event. With the exception of TN, the TSS, BOD, COD and TP loads were affected by runoff. The correlations of these items were proportional to the runoff volume, with correlation coefficients (r) greater than 0.70, which are suitable for use as NPS model data. The TSS load showed very good relationships with organics (BOD & COD) and nutrients (TN & TP), with correlation coefficients greater than 0.79. Therefore, the removal of TSS is a promising factor for protecting water basins.

• Journal of radiological science and technology
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• v.42 no.6
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• pp.441-446
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• 2019

The purpose of this paper is to recognize the usefulness of the Phantom produced with 3D printing technology by reproducing the original phantom with 3D printing technology. Using CT, we obtained information from the original phantom. The acquired file was printed by the SLA method of ABS materials. For inspection, SPECT/CT was used to obtain images. We filled the both Phantom with a solution mixed with ^99mTcO4 1 mCi in 1 liter of water and acq uired images in accordance with the standard protocol. Using Image J, the SNR for each slice of the image was obtained. As a reference images, AC images were used. For the analysis of acquired images, ROI was set in the White mater and Gray mater sections of each image, and the average Intensity Value within the ROI were compared. According to the results of this study, 3D printed phantom's SNR is about 0.1 higher than the conventional phantom. And the ratio of Intensity Value was shown in the original 1 : 3.4, and the printed phantom was shown to be 1 : 3.2. Therefore, if Calibration Value is applied, It is assumed that it can be used as an alternative to the original.

• Journal of the Korean Society of Physical Medicine
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• v.15 no.4
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• pp.87-99
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• 2020

PURPOSE: This study examines the therapeutic effect of functional adjustment procedure therapy (FAPT), by comparatively analyzing behavioral disorders due to shoulder pain and subjective pain intensity subsequent to therapy, in patients with shoulder pain. METHODS: The intervention was performed on 48 employee patients with shoulder pain, Patients were administered 16 sessions of FAPT for 8 weeks, twice a week for 30 minutes per session. This study applied the neck pain and disability scale (NPDS) as a measurement tool, and used the questionnaire to measure subjective pain intensity to investigate the difference before and after administering FAPT to employee patients with shoulder pain. RESULTS: Statistically significant difference was obtained between the mean difference in shoulder pain disorder, before and after FAPT. Assessing gender and age differences in the reduction effect of shoulder pain, showed significant difference in 8 of the 10 factors examined. Finally, examining the difference in the effect of reducing subjective shoulder pain by gender and age, we observed that gender-based disability reduction was significant for all 12 factors examined. CONCLUSION: Taken together, the results of this study, validate the therapeutic efficacy of FAPT for patients with shoulder pain. We believe that this data will provide basic information to understand the health conditions and psychological variables of patients with shoulder pain.

• Journal of The Korean Society of Integrative Medicine
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• v.7 no.4
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• pp.89-104
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• 2019

Purpose : The purpose of this study was to investigate the development of korean vowels by acoustically analyzing whether children produce Korean vowels differently according to their age and gender between ages 4 and 6. Methods : A total of 104 children aged 4~6 years (56 males and 48 females) participated in this study. The participants were classified as either 4, 5, or 6 years old. Vowel speech data was obtained by asking the subjects to pronounce meaningful words in which the vowel in question was located in the first syllable. Speech analysis was performed using the Multi-speech 3700 program. Results : Age, gender, and vowel being pronounced all had significant effects on intensity. There was significant decrease with increasing age, and the intensity was significantly higher in male children than female children. Neither age, gender, nor the vowel being produced affected the fundamental frequency. The fundamental frequency produced did not differ by age or gender. The first and second formants had considerable effect on age and vowels, significantly decreased with age, and did not have a gender difference. Conclusion : The results of this study showed that children aged 4~6 have similar anatomical structures, but that maturity of speech motor skills required to pronounce vowels was correlated with age. The results of this study can be used to evaluate children's speech and develop speech therapy programs.

• Korea-Australia Rheology Journal
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• v.19 no.2
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• pp.61-66
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• 2007

The aggregation characteristics of red blood cells (RBCs) are known as important factors in the microvascular flow system, and increased RBC aggregation has been observed in various pathological diseases, such as thrombosis and myocardial infarction. This paper describes a simple microfluidic device for measuring the RBC aggregation by integrating a microfluidic slit rheometry and laser-backscattering technique. While a decreasing-pressure mechanism was applied to the microfluidic rheometry, a syllectogram (the light intensity versus time) showed an initial increase and a peak caused by the high shear stress-induced disaggregation, immediately followed by a decrease in the light intensity due to RBC aggregation. The critical shear stress (CST) corresponding to the peak intensity was examined as a new index of the RBC aggregation characteristics. The CST of RBCs increased with increasing aggregation-dominating protein (fibrinogen) in the blood plasma. The essential feature of this design was the combination of the rheometric-optic characterization of RBC aggregation with a microfluidic chip, which may potentially allow cell aggregation measurements to be easily carried out in a clinical setting.