• The Journal of the Korea institute of electronic communication sciences
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• v.8 no.8
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• pp.1271-1276
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• 2013

This study selected 22 male subjects to examine the maintenance period of static and ballistic stretching applied to rectus femoris, divided them into 11 static stretching group and 11 ballistic stretching group and analyzed changes in median frequency and in maximal voluntary isometric contraction before stretching and at 30 sec, 1 min, 3 min, 5 min, and 10 min after stretching. Median frequency showed significant differences in changes according to time and groups after the test of main effects. It was reduced after 3 min. in both static stretching and ballistic stretching groups and then increased again. Maximal voluntary isometric contraction showed significant differences in changes according to time and groups from the results of the main effect test. Static stretching group was reduced at 3 min after the experiment and then increased after that and ballistic stretching group was reduced at 5 min after the experiment and then increased again. In conclusion, changes were shown according to time after stretching and the effects of ballistic stretching were maintained a little longer than those of static stretching.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.2072-2076
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• 2011

철도 시스템에서 철도궤도와 레일은 주요한 신호 시스템의 일부로 사용되고 있으나 콘크리트 슬래브 궤도 내부의 철근으로 인한 신호전류 감소, 교란 등을 방지하기 위해 과도한 절연작업이 필요하다. 본 연구에서는 국내에서 기 개발된 프리캐스트 슬래브 궤도의 횡방향 철근을 GFRP 보강근으로 대체하여 절연작업의 감소를 가능하게 하였다. GFRP로 보강된 프리캐스트 슬래브 궤도의 설계과정과 정적 휨 시험과 단부의 연결철근 인발 시험을 통한 거동 분석 및 고찰 내용을 제시하였다. 휨 시험과 실스케일 인발 시험의 결과 정적 휨 강도는 정립된 설계법에 의해 적절한 강도를 가지고 있으나 기 개발된 연결철근의 위치와 형태는 온도 또는 수축으로 인해 발생할 수 있는 축력을 저항할 수 없음을 확인하였다.

• Journal of the Korean Society for Precision Engineering
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• v.26 no.3
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• pp.129-136
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• 2009

The estimation of muscle force is important to understand the roles of the muscles. The static optimization method can be used to figure out the individual muscle forces. However, muscle forces during the movement including muscle co-contraction cannot be considered by the static optimization. In this study, a hybrid static optimization method was introduced to find the well-matched muscle forces with EMG signals under muscle co-contraction conditions. To validate the developed algorithm, the 3D motion analysis and its corresponding inverse dynamics using the musculoskeletal modeling software (SIMM) were performed on heel-rise movements. Results showed that the developed algorithm could estimate the acceptable muscle forces during heel-rise movement. These results imply that a hybrid numerical approach is very useful to obtain the reasonable muscle forces under muscle co-contraction conditions.

• Journal of Ocean Engineering and Technology
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• v.12 no.2 s.28
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• pp.1-21
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• 1998

In this paper, a non-conforming 3-D 8-node solid element(MQM10) has beets applied to the analyses of static and dynamic bending problems of laminated composite plates The QM10 element exhibits stiffer bending stiffness which is caused by the reduction of degree of freedom from Q11 element. As an effective way to correct the relative stiffness stiffening phenomenon the modification of Gauss sampling points for composite plates is proposed. The quantity of modification is a function of material properties. Also, another two modified equations are obtained, one is modification for stress, and the other is modification of coefficient of shear modulus in free vibration. It is noted that MQM10 element can analyse the static and free vibration problems of various 3-dimensional composite plates composed of unidirectional laminae, woven laminae or braided laminae. The results of MQM10 element are in good agreement with those of 20-node element.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.39 no.2
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• pp.147-152
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• 2015

We designed, fabricated, and tested the capacitive microsensors for skin piloerection monitoring. The performance of the skin piloerection monitoring sensor was characterized using the artificial bump, representing human skin goosebump; thus, resulting in the sensitivity of $-0.00252%/{\mu}m$ and the nonlinearity of 25.9 % for the artificial goosebump deformation in the range of $0{\sim}326{\mu}m$. We also verified two successive human skin piloerection having 3.5 s duration on the subject's dorsal forearms, thus resulting in the capacitance change of -6.2 fF and -9.2 fF compared to the initial condition, corresponding to the piloerection intensity of $145{\mu}m$ and $194{\mu}m$, respectively. It was demonstrated experimentally that the proposed sensor is capable to measure the human skin piloerection objectively and quantitatively, thereby suggesting the quantitative evaluation method of the qualitative human emotional state for cognitive human-machine interfaces applications.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.33 no.8
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• pp.807-812
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• 2009

Most structure engineers give the casting components over-estimated factor of safety without any reasonable foundation due to the worries about the unavoidable defects such as shrinkages and porosity in castings; the engineers have little knowledge on the relation between the defect and structural behavior. And the workers in casting field also do not know how to control the defects by manufacturing; they do not know to where the defects move or until how size they reduce the defects. In this study, shrinkage defect was scanned by industrial computerized tomography instrument (CT), and subsequently was modeled to a spheroid primitive for structural analysis. Using these simplified models of shrinkage, we observed the effects of the defect on the results of the structural analysis. A commercial structural analysis code was used to do the analysis works. Considering the conclusions, it is possible to manage the shrinkages effectively in casting process and to design the products with more reliable

• Journal of Biomedical Engineering Research
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• v.21 no.4
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• pp.411-417
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• 2000

This paper describes the analysis of the oscillometric method based on the shape of arterial pressure and proposal of a new algorithm for estimating the blood pressure by computer simulation. In the first step, the arterial pressure model which is able to control the shape of arterial pressure was designed and then we simulated the oscillometric model using both the existing exponential model showing the static arterial pressure-volume relation and the designed arterial pressure model. By analyzing the correlation of characteristic ratio based on the shape of arterial pressure, we could find that the characteristic ratio was not the only standard parameter for estimating systolic and diastolic pressure. We were able to estimate the shape of arterial pressure by computing the correlation of arterial pressure shape with oscillation shape. Finally, we proposed an algorithm which is able to estimate systolic and diastolic pressure according to pressure(Pp) table constructed from the relation of maximum amplitude of oscillation and arterial pressure shape. We tested 60 arterial pressure waveforms having various arterial pressure shape and pulse. As a results, the absolute deviation average values of the estimation of systolic, diastolic and mean pressure were 1.62%, 2.40% and 2.20%, respectively. In conclusions, the proposed algorithm showed the possibility of usefullness in estimating the blood pressure.

• Sleep Medicine and Psychophysiology
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• v.9 no.1
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• pp.24-33
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• 2002

Objectives: Nasal continuous positive airway pressure (CPAP) corrected elevated blood pressure (BP) in some studies of obstructive sleep apnea syndrome (OSAS) but not in others. Such inconsistent results in previous studies might be due to differences in factors influencing the effects of CPAP on BP. The factors referred to include BP monitoring techniques, the characteristics of subjects, and method of CPAP application. Therefore, we evaluated the effects of one night CPAP application on BP and heart rate (HR) reactivity using non-invasive beat-to-beat BP measurement in normotensive and hypertensive subjects with OSAS. Methods: Finger arterial BP and oxygen saturation monitoring with nocturnal polysomnography were performed on 10 OSAS patients (mean age $52.2{\pm}12.4\;years$; 9 males, 1 female; respiratory disturbance index (RDI)>5) for one baseline night and another CPAP night. Beat-to-beat measurement of BP and HR was done with finger arterial BP monitor ($Finapres^{(R)}$) and mean arterial oxygen saturation ($SaO_2$) was also measured at 2-second intervals for both nights. We compared the mean values of cardiovascular and respiratory variables between baseline and CPAP nights using Wilcoxon signed ranks test. Delta ($\Delta$) BP, defined as the subtracted value of CPAP night BP from baseline night BP, was correlated with age, body mass index (BMI), baseline night values of BP, BP variability, HR, HR variability, mean $SaO_2$ and respiratory disturbance index (RDI), and CPAP night values of TWT% (total wake time%) and CPAP pressure, using Spearman's correlation. Results: 1) Although increase of mean $SaO_2$ (p<.01) and decrease of RDI (p<.01) were observed on the CPAP night, there were no significant differences in other variables between two nights. 2) However, delta BP tended to increase or decease depending on BP values of the baseline night and age. Delta systolic BP and baseline systolic BP showed a significant positive correlation (p<.01), but delta diastolic BP and baseline diastolic BP did not show a significant correlation except for a positive correlation in wake stage (p<.01). Delta diastolic BP and age showed a significant negative correlation (p<.05) during all stages except for REM stage, but delta systolic BP and age did not. 3) Delta systolic and diastolic BPs did not significantly correlate with other factors, such as BMI, baseline night values of BP variability, HR, HR variability, mean SaO2 and RDI, and CPAP night values of TWT% and CPAP pressure, except for a positive correlation of delta diastolic pressure and TWT% of CPAP night (p<.01). Conclusions: We observed that systolic BP and diastolic BP tended to decrease, increase or remain still in accordance with the systolic BP level of baseline night and aging. We suggest that BP reactivity by CPAP be dealt with as a complex phenomenon rather than a simple undifferentiated BP decrease.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.3D
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• pp.435-444
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• 2006

This paper investigates the effect of 3-dimensional FE models to evaluation results of jointed concrete pavements which is back-calculated by AREA method. Sensitivity of 3-dimensional FE models developed to simulate the behavior of real jointed concrete pavement are analyzed after compared with 2-dimensional FE models using ILLISLAB. In comparison with 2-dimensional models, influence of concrete contraction under loading plate and base layer on surface deflections is more than that of loading configuration. Deflections at 3-dimensional model between linear and nonlinear temperature distribution under same temperature difference are similar, but noticeable differences are investigated in low elastic modulus of foundations. Dynamic deflections under loading plate are larger than static deflections in high elastic modulus of foundation, but smaller in low elastic modulus. Lower dynamic modulus of subgrade reactions are backcalculated by dynamic deflections than by static deflections. But reverse trend is investigated in the backcalculated elastic modulus of concrete which describes trends of the field backcalculation values calculated from AREA method.

• Journal of the Korea Concrete Institute
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• v.22 no.4
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• pp.567-574
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• 2010

As a eco-friendly material, Hwangtoh(red clay) has been studied for a partial or complete replacement of portland cement. Most of existing studies focused on the mechanical properties of the Hwangtoh concrete including the compressive strength, drying shrinkage, creep. In the present study, the flexural capacity of the beams made with the Hwangtoh concrete was tested. One of the concrete tested consisted of activated Hwangtoh replacing 20% of the cement. The other consisted 100% activated Hwangtoh replacing all the cement. The simple beams were tested under two point static loading. The flexural strength, cracking moment, deflection, and ductility were compared with those of the beams made with ordinary portland cement concrete.