• Journal of Electrochemical Science and Technology
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• 제7권1호
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• pp.52-57
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• 2016

Nanoporous-layer-covered TiO₂ nanotube arrays (Type II TNTs) were fabricated by two-step electrochemical anodization. For comparison, conventional TiO₂ nanotube arrays (Type I TNTs) were also prepared by one-step electrochemical anodization. Types I and II TNTs were detached by selective etching and then transferred successfully to a transparent F-doped SnO₂ (FTO) substrate by a sol-gel process. Both FTO/Types I and II TNTs allowed front side illumination to exhibit incident photon-to-current efficiencies (IPCEs) in the long wavelength region of 300 to 750 nm without the absorption of light by the iodine-containing electrolyte. The Type II TNT exhibited longer electron lifetime and faster charge transfer than the Type I TNT because of its relatively fewer defect states. These beneficial effects lead to a high overall energy conversion efficiency (5.32 %) of the resulting dye-sensitized solar cell.

• 대한기계학회논문집
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• 제19권8호
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• pp.1950-1963
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• 1995

A modification of the approximate-factorization method is made to accelerate the convergency rate and to take sufficiently large Courant number without loss of accuracy. And a stable implicit finite-difference scheme for solving the incompressible Navier-Stokes equations employed above modified method is developed. In the present implicit scheme, the volume fluxes with contravariant velocity components and the pressure formulation in curvilinear coordinates is adopted. In order to satisfy the continuity condition completely and to remove spurious errors for the pressure, the Navier-Stokes equations are solved by a modified SMAC scheme using a staggered gird. The upstream-difference scheme such as the QUICK scheme is also employed to the right hand side. The implicit scheme is unconditionally stable and satisfies a diagonally dominant condition for scalar diagonal linear systems of implicit operator on the left hand side. Numerical results for some test calculations of the two-dimensional flow in a square cavity and over a backward-facing step are obtained using both usual approximate-factorization method and the modified one, and compared with each other. It is shown that the present scheme allows a sufficiently large Courant number of O(10$^{2}$) and reduces the computing time.

• 대한조선학회 특별논문집
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• 대한조선학회 2006년도 특별논문집
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• pp.97-105
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• 2006

Until now, we are designing the breakwater of container vessel as cantilever structure ypically. Recently, we have designed "side shell touch type breakwater" for the first time to 6,200TEU Class Container Carrier registered on Lloyd Classification. The Lloyd Rule does not provide requirements for breakwater scantling but only recommend breakwater wave load and Lloyd Class requests for submitting the calculation results. At early design step, we had reviewed the breakwater structure through the calculation of simple beam theory with wave load recommended by Lloyd and referring to already built same size of container vessel. At the same time we had carried out F.E.M analysis of breakwater structure and had updated design, so we could verify the strength of side shell touch type breakwater at final step.

• 대한물리의학회지
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• 제13권1호
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• pp.81-88
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• 2018

PURPOSE: The present study aims to determine the effect of lower extremity muscle strength exercise at the non-paralyzed side of patients of stroke using a mirror on gait and balance. METHODS: Subjects were assigned randomly to a group of lower extremity exercise without using a mirror (n=10), a group of lower extremity motion exercise using a mirror (n=10), and a group of lower extremity muscle strength exercise using a mirror (n=10). The exercise is added to a physiotherapy program conducted at the hospital and subjects conducted their designed lower extremity exercises 30 times a day (5 sets), five days per week for four weeks. RESULTS: The study result showed that BBS(Berg balance scale)(p<.05) and TUG(timed up and go test)(p<.05) had a significant difference. In the comparison on gait ability, stride length, step length, step width and single support was a significant difference within two groups using a mirror before and after the intervention(p<.05). CONCLUSION: Conclusively, low extremity motion exercise using a mirror and low extremity muscle strength exercise using a mirror conducted along with general physiotherapy exercises had a positive effect on functions of lower extremity in patients with stroke and the recovery of paralyzed side thereby incurring a significant difference in balance and gait abilities.

• Journal of Power Electronics
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• 제18권3호
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• pp.662-671
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• 2018

This paper presents a new structure for a step up dc-dc converter, which has several advantageous features. Firstly, the input dc source and the clamped capacitor are connected in series to transfer energy to the load through dual voltage multiplier cells. Therefore, the proposed converter can produce a very high voltage and a high conversion efficiency. Secondly, a double voltage clamped circuit is introduced to the primary side of the coupled inductor. The energy of the leakage inductance of the coupled inductor is recycled and the inrush current problem of the clamped circuits can be shared equally by two synchronous clamped capacitors. Therefore, the voltage spike of the switch tube is solved and the current stress of the diode is reduced. Thirdly, dual voltage multiplier cells can absorb the leakage inductance energy of the secondary side of the coupled inductor to obtain a higher efficiency. Fourthly, the active switch turns on at almost zero current and the reverse-recovery problem of the diodes is alleviated due to the leakage inductance, which further improves the conversion efficiency. The operating principles and a steady-state analysis of the continuous, discontinuous and boundary conduction modes are discussed in detail. Finally, the validity of this topology is confirmed by experimental results.

• 대한물리의학회지
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• 제12권2호
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• pp.21-31
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• 2017

PURPOSE: The purpose of this study was to identify whether backward walking exercise was more effective than conventional physical therapy for balance and gait in hemiplegic stroke patients. METHODS: Eighteen patients with chronic stroke were randomly assigned to the experimental (n=9) or control (n=9) group. The experimental and control group performed backward walking exercise and conventional physical therapy, respectively, for 8 weeks. Stability Index (SI) and Weight Distribution Index (WDI) during standing were assessed using the Tetrax Balance System. The Timed Up and Go (TUG) test and Korean version of the Berg Balance Scale (K-BBS) were used to evaluate balance and fall risk. Walking speed, stride length, and step length on the affected side were measured using the 10-Meter Walk and ink foot printing tests. Wilcoxon signed-rank and Mann-Whitney U tests were used for within- and between- group comparisons, respectively. RESULTS: The experimental group showed significantly higher changes in SI (p<.01), WDI (p<.01), TUG (p<.001), and BBS score (p<.001) following intervention compared with the control group. The experimental group also showed significantly greater improvements in walking speed (p<.01), stride length (p<.001), and step length on the affected side (p<.001) after intervention compared with the control group. CONCLUSION: Backward walking exercise is an effective intervention to improve balance and gait in hemiplegic stroke patients.

• Journal of Magnetics
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• 제20권2호
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• pp.129-132
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• 2015

The aim of the present study was to examine whether repetitive transcranial magnetic stimulation (rTMS) can improve gait ability of acute stage stroke patients. This study was conducted with 39 subjects who were diagnosed as having a hemiparesis due to stroke. The experimental group included 20 subjects who underwent repetitive transcranial magnetic stimulation and the control group included 19 subjects who underwent sham therapy. The stroke patients in the experimental group underwent conventional rehabilitation therapy and rTMS was applied daily to the hotspot of the lesional hemisphere. The stroke patients in the control group underwent sham rTMS and conventional rehabilitation therapy. Participants in both groups received therapy five days per week for four weeks. Temporospatial gait characteristics, such as stance phase, swing phase, step length in affected side, velocity, and cadence, were assessed before and after the four week therapy period. A significant difference was observed in post-treatment gains for the step length in the affected side, velocity, and cadence between the experimental group and control group ( p < 0.05). However, no significant differences were observed between the two groups on stance phase and swing phase ( p > 0.05). We conclude that rTMS may be beneficial in improving the effects of acute stage stroke on gait ability.

• 한국자기학회:학술대회 개요집
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• 한국자기학회 2011년도 자성 및 자성재료 국제학술대회
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• pp.29-30
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• 2011

We have demonstrated the fabrication of sub 30 nm MTJ pillars with PMA characteristics. The multi-step IBE process performed at $45^{\circ}$ and $30^{\circ}$, using NER resulted in almost vertical side profiles. There deposition on the sidewalls of the NER prevented lateral etching of the resist hard mask allowing vertical MTJ side profile formation without any reduction in the lithographically defined resist lateral dimensions. For the 28nm STT-MTJ pillars, the measured TMR ratio was 13 % with resistance of 1 $k{\Omega}$, which was due to remaining redeposition layers less than 0.1 nm thick. With further optimization in multi-step IBE conditions, it will be possible to fabricate fully operating sub 30 nm perpendicular STT-MTJ structures for application to future non-volatile memories.

• 한국전문물리치료학회지
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• 제20권4호
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• pp.40-46
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• 2013

The purpose of this study was to determine which spatiotemporal gait parameters obtained during hemiplegic walking could be a predictive factor for the Timed Up and Go test (TUG). Two hundreds nine subjects who had suffered a stroke were recruited for this study. They were participated in two assessments; the TUG test and gait analysis. The relationship between the TUG test and spatiotemporal parameters was analyzed using Pearson's correlation coefficients. In addition, to predict the spatiotemporal gait parameters that correlated most with the TUG scores, we used multiple linear regression analyses (stepwise method). The results show that the normalized velocity was strongly correlated with the TUG performance (r=-.72, p<.001). Additionally, single support percentage (SSP), double support percentage (DSP), step time difference (STD), and step length difference (SLD) significantly were correlated with the TUG test. Normalized velocity, STD, DSP of affected side, and SSP of non-affected side explained 53%, 8%, 3%, 2%, of variance in the TUG test respectively. In conclusion, an increase in gait velocity and a decrease in STD would be effective indicators of improvement on the functional mobility in the stroke rehabilitation.

• PNF and Movement
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• 제18권1호
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• pp.87-95
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• 2020

Purpose: The purpose of this study was to investigate the effect of whole-body vibration training on the flexibility and agility of professional soccer players. Methods: Sixteen professional soccer players participated voluntarily in the study. Subjects were allocated to two groups: the experimental group received whole-body vibration (WBV) and team training, and the control group received only team training. Team training was conducted in 15 sessions of 70 min duration over 3 weeks. WBV training was applied at 40 Hz frequency, 5 sets (1 min-training, 1 min-resting) in a squatting position. Outcomes from sit-and-reach, side-step test, burpee test, and T-test were measured before and after training. To examine pre- and post-intervention differences between the two groups, a paired t-test was used. Independent t-tests were performed to compare pre- and post-test scores and the time difference of the two groups. Results: Significant improvements in sit-and-reach and agility variables were observed in the experimental group (p < 0.05). In particular, flexibility (sit-and-reach) and agility (the side-step test and the burpee test) were significantly different between the two groups (p < 0.05). Conclusion: These findings suggest that whole-body vibration training has a positive effect on performance enhancement for professional soccer players.