• Journal of Korean Ophthalmic Optics Society
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• v.21 no.3
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• pp.259-264
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• 2016

Purpose: To establish the cause of decrease in body stability and to analyze the effects on sensory organs maintaining static balance according to the induced astigmatic blur. Methods: Twenty subjects (10 males, 10 females; mean age, $23.40{\pm}2.70years$) were participated in this study. To induce myopic simple astigmatism, the axis directions of cylindrical lenses were placed $180^{\circ}$ on both eyes (with-the-rule), $90^{\circ}$ on both eyes (against-the-rule), and $45^{\circ}$ on both eyes (oblique). Cylindrical lenses of +0.50, +1.00, +1.50, +2.00, +3.00, +4.00, and +5.00 D were used to increase astigmatic blur in each astigmatism types. General stability (ST) and sway power (SP) in frequencies by each sensory organs were analyzed using the TETRAX biofeedback system. Results: ST in the all astigmatism types were raised with increase of astigmatic blur compared to full corrected condition, but a significant difference only showed in the induced oblique astigmatism. According to the results of correlation analysis between ST and SP in the each frequencies with increase of astigmatic blur, the causes of increased ST in the induced oblique astigmatism showed to have a high correlation in order of somatosensory system (high-medium frequency), central nervous system (high frequency), peripheral vestibular system (low-medium frequency), and visual system (low frequency). Conclusions: The visual information by uncorrected oblique astigmatism may disturb the normal functions of all sensory organs maintaining body balance, consequently, the body stability can be reduced. Therefore, optimal correction of astigmatism can play an important role for reducing the instability of body balance.

• Journal of Dental Rehabilitation and Applied Science
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• v.21 no.2
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• pp.153-167
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• 2005

The purpose of this study was to compare the v-shape thread with the square shape thread of fixture in the view of stress distribution pattern using finite element stress analysis. The finite element model was designed with the parallel placement of two standard fixtures(4.0 mm diameter ${\times}$ 11.5 mm length) on the region of mandibular 1st and 2nd molars. Three dimensional finite element model was created with the components of the implant and surrounding bone. This study simulated loads of 200 N at the central fossa in a axial direction (load A), 200 N at the buccal offset load that is 2 mm apart from central fossa in a axial direction (load B), 200 N at the buccal offset load that was 4 mm apart from central fossa in a axial direction (load C). These forces of load A',B',C' were applied to a $15^{\circ}$ inward oblique direction at that same site with 200 N. Von Mises stress values were recorded and compared in the supporting bone, fixture, and abutment screw. The following results have been made based on this study : 1. The highest stress concentration occurred at the cervical region of the implant fixture. 2. Von Mises stress value of off-site region was higher than that of central fossa region. 3. Square shape thread type showed more even stress distribution in the vertical and oblique force than V-shape thread type. 4. Stress distribution was the most effective in the case of buccal offset load (2, 4 mm distance from central fossa) in the square shape thread type. 5. V-shape thread type revealed higher von Mises stress value than square shape thread type in all environmental condition. The results from numerical analyses concluded that square shape thread type had the lower destructive stress and more stress distribution between the fixture and bone interface than V-shape thread type. Therefore, square shape thread type was regarded as optimal thread configuration in biomechanical concepts.

• Physical Therapy Korea
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• v.19 no.2
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• pp.1-11
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• 2012

The pelvic compression belt (PCB) contributes to improving sacroiliac joint stability, and it has been used as an additional therapeutic option for patients with sacroiliac joint pain (SIJP). This study aimed to investigate whether the muscle activation patterns of the supporting leg was different between asymptomatic subjects and subjects with SIJP during one-leg standing, and how it changes with the PCB. 15 subjects with SIJP and 10 asymptomatic subjects volunteered to participate in this study. Surface electromyography (EMG) data (reaction time [RT] and muscle activation) were collected from the internal oblique, lumbar multifidius, gluteus maximus and biceps femoris muscles during one-leg standing with and without the PCB. Without the PCB condition, in the SIJP group, the biceps femoris muscle showed the fastest RT among all muscles (p<.05), whereas in the asymptomatic group, the RT of the internal oblique muscle was the most rapid (p<.05). In condition without the PCB, the biceps femoris EMG amplitudes in the SIJP group were significantly greater than that in the asymptomatic group (p<.05). After the application of the PCB, the RT of the biceps femoris muscle was significantly increased only in the SIJP group (p<.05). Moreover, the biceps femoris EMG amplitudes significantly decreased and the gluteus maximus EMG amplitudes significant increased only in the SIJP group by applying the PCB (p<.05). However, this had no such effect on the gluteus maximus and biceps femoris EMG patterns in the asymptomatic group (p>.05). Thus, this study supports the applying the PCB to patients with SIJP can be used as a helpful option to modify the activation patterns of the gluteus maximus and biceps femoris muscle.

• 한국정보디스플레이학회:학술대회논문집
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• 2004.08a
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• pp.1132-1136
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• 2004

In this paper, we intend to make FFS mode cell with LC alignment used non-rubbing method, ion beam alignment method on the a-C:H thin film, to analyze electro-optical characteristics in this cell. We studied on the suitable inorganic thin film for FFS-LCD and the aligning capabilities of nematic liquid crystal (NLC) using the new alignment material of a-C:H thin film as working gas at rf bias condition. A high pretilt angle of about 5$^{\circ}$ by ion beam(IB) exposure on the a-C:H thin film surface was measured. An excellent voltage-transmittance (V-T) and response time curve of the ion-beam-aligned FFS-LCD was observed with oblique ion beam exposure on the DLC thin films.

• The Journal of Korean Physical Therapy
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• v.32 no.5
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• pp.273-276
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• 2020

Purpose: The purpose of this study was to investigate the effects of the resistance conditions on the electromyography (EMG) activity ratio of vastus medialis oblique (VMO) and vastus lateralis (VL) muscle during partial lunge exercise in healthy subjects in order to suggest the basic data of exercise intervention for such as patients with patellofemoral pain syndrome (PFPS). Methods: The participants of this study were healthy twenty two people with no knee pain, limitation of motion and past history of operation at lower extremity. The participants performed three types of lunge 1) no resistance, 2) anterolateral 45° resistance and 3) lateral 90° respectively. The EMG activity of the VMO and VL were recorded by surface EMG and the measured data normalized by the %MVIC value was analyzed by repeated measured ANOVA. Results: The results showed that the VMO/VL EMG activity ratio during lunge with anterolateral 45° resistance was significantly higher than with no resistance and lateral 90° resistance (p<0.05). There was no significant difference in VMO, VL, and VMO/VL muscle activity between male and female subjects (p>0.05). Conclusion: This study suggests that partial lunge exercise with anterolateral 45° resistance can increase the VMO/VL muscle activity in healthy subjects. This result could be used as basic data to develop therapeutic exercise programs such as PFPS patients.

• Journal of Ocean Engineering and Technology
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• v.25 no.1
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• pp.22-26
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• 2011

The resistance performances of a small leisure yacht with two different keels, center and double, respectively, are investigated using a model test at circulating water channel and CFD analysis. Flow patterns around the keels are observed using a tuft test to make clear the relation between the resistance performance and the flow characteristics around the keels. The results show that the keel does not affect free surface flows and that the double keel yacht has better performance compared to a single keel yacht in oblique condition from the resistance point of view.

• The Journal of Korean Physical Therapy
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• v.25 no.5
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• pp.316-321
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• 2013

Purpose: The aimed of this study was to investigate muscle activation related to postural stability according to different frequency of whole body vibration during quiet standing, to identify the most effective training conditions that cause the highest neuromuscular responses, and to evaluate the difference of EMG activation according to the anatomical position of the muscle - proximal or distal from the vibration platform. Methods: Eighteen healthy subjects voluntarily participated in this single-group, repeated-measures study in which EMG data from upper trapezius, rectus abdominalis, external oblique abdominalis, elector spinae, gluteus maximus, rectus femoris, semitendinosus, and gastrocnemius were collected over different frequencies (0-5-10-15-20-25Hz) for each subject during quiet standing. Results: We observed a statistically significant difference in the mean values of %RVC of muscular activation according to different frequencies of whole body vibration during quiet standing in all muscles (p<0.05). Conclusion: Our results indicate that lower frequencies of vibration result in low muscular activation, and higher frequencies elicit high muscular activation. However, the most effective training condition that caused the highest activation was 20 Hz. In addition, the proximally located lower extremity muscles (GCM, RF, ST, GM) showed higher activation than the distally located trunk and neck muscles (ES, EO, RA, UT) together with increasing frequency.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.33 no.4
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• pp.1455-1462
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• 2013

This study examines the reflection of a partially perforated wall with single chamber by 2D and 3D hydraulic experiments. The effects of slit shape on the front wall, relative chamber width and wave steepness were discussed. For the normal incident wave condition, the reflections of horizontal slit case were lower than that of the vertical slit with the similar porosity, but the differences are not significant. When the wave steepness is relatively small, the reflection coefficients are large. In the oblique incidence, the normalized wave heights along a perforated wall with similar porosity are almost same for the vertical and horizontal slit walls and therefore the difference by slit shape can be ignored.

• Journal of Mechanical Science and Technology
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• v.15 no.12
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• pp.1816-1821
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• 2001

Two-dimensional blow-down type supersonic wind tunnel was designed and built to investigate the transient behavior of the startup of a supersonic flow from rest. The contour of the divergent part of the nozzle was determined by the MOC calculation. The converging part of the nozzle, upstream of fille throat was contoured to make the flow uniform at the throat. The flow characteristics of the steady supersonic condition were visualized using the high-speed schlieren photography. The Mach number was evaluated from the oblique shock wave angle on a sharp wedge with halt angle of 5 degree. The measured Mach number was 2.4 and was slightly less than the value predicted by the design calculation. The initial transient behavior of the nozzle was recorded by a high-speed digital video camera with schlieren technique. The measured transition time from standstill to a steady supersonic flow was estimated by analyzing the serial images. Typical transition time was approximately 0.1sec.

• Proceedings of the KSME Conference
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• 2001.11b
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• pp.260-267
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• 2001

The objective of this study was to investigate the characteristics of jet flow and heat transfer caused by trapezoid rods array in impinging jet system. In this study, trapezoid rods have been set up in front of flat plate to serve as a turbulence promoter. The bottom width of trapezoid rod was W=4, 8mm and oblique angle were $80^{\circ}$. The space from rods to the heating surface was C=1, 2, 4mm, the pitch between each rods was P=30, 40, 50mm, and the distance from nozzle exit to flat plate was H=100, 500mm. This results were compared with the case without trapezoid rods. As a result, when rods are installed in front of the impinging plate, the acceleration of the jet flow and the eddies due to the rods seem to contribute to the heat transfer enhancement. Among test conditions, the heat transfer performance was best for the condition of W=8mm, C=1mm, P=30mm and H/B=10. The maximum heat transfer rate is about 1.9 times larger than that without trapezoid rods.