• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.05a
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• pp.259-260
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• 2006

The ESPI(Electronic Speckle Pattern Interferometry) is a real time, full-field, non-destructive optical measurement technique. In this study, ESPI is proposed for the purpose of vibration analysis for new material, composite material. Composite materials have various complicated characteristics according to the ply materials, ply orientations, ply stacking sequences and boundary conditions. Therefore, it is difficult to analysis composite materials. For efficient use of composite materials in engineering applications the dynamic behavior, that is, natural frequencies, nodal patterns should be informed. If use Time-Average ESPI, can analyze vibration characteristic of composite material by real time easily. This study manufactured laminated composite of symmetry, asymmetry two kinds that is consisted of CFRP(Carbon Fiber Reinforced Plastics) and shape of test piece is rectangular form.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.2
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• pp.124-132
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• 2020

This study examines the clinical availability of alpha amplitude, asymmetry and mean frequency in old age as EEG indexes reflecting brain health condition. The EEGs of prefrontal lobes in eye closure state were measured for 4 minutes with 72 male and female elderly people aged 73. Subjects were divided into higher and lower groups based on average values of alpha amplitude, asymmetry and mean frequency. The results of correlations and t-test among EEG indexes were as follows. First, the higher Alpha altitude was, the higher physical and mental stress resistance and left-to-right brain communication were, and the lower mean Alpha mean frequency location was. The higher Alpha asymmetry was, the lower left-to-right communication level was. Second, as Alpha power of right brain was higher than that of left brain, Alpha amplitude and mental stress resistance and left-to-right brain communication level were higher. Third, as Alpha mean frequency location was higher, Alpha amplitude and mental anti-stress level were lowered and arousal level was enhanced. These high correlations and complementary meaning among quantitative EEG indicators demonstrated the possibility of biomarkers reflecting brain health state in old age.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.11a
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• pp.918-922
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• 2007

Aero-pulsation noise, generally caused by geometric asymmetry of a rotating device, is considerable source of annoyance in passenger cars using the turbocharged diesel engine. Main source of this noise is the compressor wheel in the turbocharger system, and can be reduced by after-treatment such as silencers, but which may increase the manufacturing cost. More effective solution is to improve the geometric symmetry over all, or to control the quality of components by sorting out inferior ones. The latter is more effective and reasonable than the former in view of manufacturing. So, an appropriate discrimination method should be needed to evaluate aero-pulsation noise level at the production line. In this paper, we introduce the accurate method which can measure the noise level of aeropulsation and also present its evaluation criteria. Besides verifying the reliability of a measurement system - a rig test system -, we analyze the correlation between the results from rig tests and those from vehicle tests. The gage R&R method is carried out to check the repeatability of measurements over 25 samples. From the result, we propose the standard specification which can discriminate inferior products from superior ones on the basis of aero-pulsation noise level.

• Proceedings of the Korean Society for Emotion and Sensibility Conference
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• 2001.05a
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• pp.225-230
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• 2001

Intensity of background noise is a factor significantly affecting both subjective evaluation of experienced stress level and associated electroencephalographic (EEG) responses during mental load in noisy environments. In the study on 27 subjects we analyzed the influence of the background white noise (WN) intensity on psychophysiological responses during a word recognition test. Electrocortical activity were recorded during baseline resting state and 40 s long performance on 3 similar Korean word recognition tests with different intensities of background WN (55, 70 and 85 dB).. An important finding in terms of physiological reactivity was similarity of all physiological response profiles between 55 and 70dB WN, i.e., none of physiological variables differentiated the two conditions, while 85dB WN resulted in a significantly different profile of reactions (higher fast beta power in EEG spectra). This condition was characterized by highest subjective rating of experienced stress, had more fast beta activity and had tendency of right hemisphere dominance, emphasizing the role of brain lateralization in negative affect control.

• The Journal of Korean Academy of Orthopedic Manual Physical Therapy
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• v.1 no.1
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• pp.37-48
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• 1995

The correlation between mobility abnormalities and positional findings(pelvic asymmetry) is essential for complete pelvic girdle evaluation. For mobility tests, there are four tests include : 1. Standing forward bending test. 2. Seated forward bending test. 3. Posterior anterior sacral pressures. 4. Kinetic test. To determine specific pelvic dysfunction, positional findings should bo assessed with bony landmarks. According to the assessment findings, the suggested order of treatment is as follows. 1. Pubic malalignment. 2. Sacroiliac dysfunction. 3. Iliosacral dysfunction. Many of the pelvic dysfunctions will respond to the simplified approach as shown in this paper but some dysfunctions will require more specific treatment.

• Journal of Korean Physical Therapy Science
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• v.2 no.1
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• pp.431-443
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• 1995

The correlation between mobility abnormalities and positional findings(pelvic asymmetry) is essential for complete pelvic girdle evaluation. For mobility tests, there are four tests include : 1. Standing forward bending test. 2. Seated forward bending test. 3. Posterior anterior sacral pressures. 4. Kinetic test. To determine specific pelvic dysfunction, positional findings should bo assessed with bony land-marks. According to the assessment findings, the suggested order of treatment is as follows. 1. Pubic malalignment 2. Sacroiliac dysfunction. 3. Iliosacral dysfunction. Many of the pelvic dysfunctions will respond to the simplified approach as shown in this paper but some dysfunctions will require more specific treatment.

• Transactions of Materials Processing
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• v.16 no.6
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• pp.447-451
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• 2007

The springback characteristics of AZ31B magnesium alloy sheet was investigated in OSU draw/bend test Springback is the elastically-driven change of shape of a part after forming and it should be estimated and controlled to manufacture more precise products in sheet forming. Magnesium alloy sheets have unique mechanical properties such as high in-plane anisotropy/asymmetry of yield stress and hardening response. So, there will be a difference in the prediction of springback with symmetric mechanical properties for magnesium alloy sheets. In this work, the Strip draw/bend tests were conducted with various conditions - die radius, sheet thickness and controlled tensile force and the tendency of springback angle was observed from the tests.

• Membrane Journal
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• v.19 no.1
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• pp.25-33
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• 2009

PES (polyethersulfone) membranes with highly enhanced their asymmetry were prepared by phase inversion process. The membranes were prepared by using PES/DMF (N,N-dimethylformamide)/TSA (p-toluenesulfonic acid)/PVP (polyvinylpyrrolidone) casting solution and water coagulant. The pre-coagulation of membrane surface which was induced by an addition of TSA as a demixing agent and PVP as a swelling polymer in the PES solution and humid exposure time, played a crucial role in determining morphological properties and the PWP (pure water permeation) performance. The PES solution was coated on polyester film under condition of 80% humidity for a while ($72{\sim}144$ sec) before immersing in a coagulation bath. The characterization of membranes was carried out by a capillary flow porometer, a FE-SEM and a permeation test apparatus. As the thickness of the smallest pore size layer (SPL) decreased, the asymmetry of membrane increased under conditions of 20 wt% of TSA and 10 wt% of PVP in 11 wt% of PES solution during longer humid contact time. As a result, the membranes showed a remarkable increase of PWP.

• Journal of the Korea Convergence Society
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• v.10 no.11
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• pp.345-352
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• 2019

This paper examines the opportunistic behavior of corporate insiders and analyzes the relationship between equity change and the possibility of delisting. The findings are summarized as follows. First, the larger the stake reduction of insider, the greater the negative excess return after announcement. In the delisting firm group, there is a significant decrease in equity and statistically significant results in the difference test between the comparative groups. The logistic regression analysis showed that the regression coefficient of equity change was negatively statistically significant, indicating a significant correlation between insider share change and the possibility of delisting. These findings are expected not only to provide useful information for investors, but also to be evidence of capital market information asymmetry.

• Physical Therapy Korea
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• v.8 no.3
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• pp.97-105
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• 2001

The purpose of this study was to investigate the effect of functional strengthening exercise on static and dynamic standing balance in a child with cerebral palsy. The subject was a 7 year old boy with diplegia whose Gross Motor Function Measure (GMFM) score was 80% along with G1 of the lower extremities in Modified Ashworth Scale. The subject was ambulatory with some degree of limitation and demonstrated muscle weakness and strength asymmetry in the lower extremities. A changing criterion design for a single-subject research was used for this study. The functional strengthening exercise consisted of lower extremity ergometer exercise and knee exercise with grading movement in standing position, each for 20 minutes, which lasted 18 sessions for 6 weeks. A knee extensor strength test on both extremities and standing balance test were conducted after each functional strengthening exercise. Two types of standing balance were tested: one leg stance test and functional reach test. One leg stance test was to evaluate static standing balance, and functional reach test was to evaluate dynamic standing balance. The results showed that the functional strengthening exercise had some positive effects on improvement of both static and dynamic standing balance, and there was a positive correlation between the knee strength and standing balance.