• Proceedings of the Korean Society of Marine Engineers Conference
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• 2005.11a
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• pp.86-87
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• 2005

The combustion characteristics of the D.I. diesel engine are largely dependent on the air-fuel ratio and the gas exchange process. The main factors are the shape of combustion chamber, fuel injection system, air flow inside the cylinder, intake air mass flow rate and so forth. Because these factors affect the combustion in a mutual and combined manner, it is very important to clearly understand the correlation of these factors in order to provide the combustion improvement plans. In this paper, we studied the performance and the gas exchange process of marine four-stroke engine using the engine cycle simulation. Also, we predicted briefly turbocharger engine matching.

• The Korea Journal of Herbology
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• v.26 no.1
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• pp.75-80
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• 2011

Objectives : The aim of the present study is to investigate the hypotensive effect of Samhwangsasim-tang (SHSST), Samigangap-tang (SMGAT) and Bangtan-tang (BTT) in stroke-prone spontaneously hypertensive rats (SHR-SP). Methods : SHR-SP rats were treated with SHSST, SMGAT and BTT at dose of 200 mg/kg/day orally for 5 weeks, respectively. Results : Treatment SHR-SP rats with SMGAT significantly lowered blood pressure but not in the SHSST or BTT treat groups. On the other hand, SHSST, SMGAT and BTT ameliorated endothelium-dependent and independent vascular relaxation in the phenylephrine-precontracted aorta and carotid artery, respectively. Conclusions : These results indicated that SMGAT has an antihypertensive effect and SHSST, SMGAT and BTT improve vascular function in stroke-prone hypertensive rat model, respectively.

• Journal of The Korean Society of Integrative Medicine
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• v.3 no.4
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• pp.69-78
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• 2015

Purpose: The purpose of this study was to identify whether inclined treadmill gait training with rhythmic auditory simulation (RAS) could improve on balance and gait in stroke patients. Method: Fifteen stroke patients who had agreed with the study were allocated to the group 1(n=5), group 2(n=5), or group 3(n=5). The group 1, group 2 and group 3 performed RAS with inclined treadmill gait training, inclined treadmill gait training and treadmill without incline gait training respectively for 3 weeks (30 minutes per session, 5 times in a week). The balance was assessed using Timed Up & Go (TUG) and Berg Balance Sale (BBS), and the gait was evaluated using 6 Minutes Walking Test (6MWT) and spatio-temporal walking variables as walking speed, cadence, Single Limb Support of affected side(SLS) and Symmetric Index(SI) before and after training. Result: Both the group 1 and group 2 showed significant improvement after training in all variables of balance and gait. The group 3 showed significant improvement in TUG values, 6MWT values, walking speed, cadence and SI. The changes in the group 1 were significantly greater in all dependent variables of balance and gait than those of the group 2 and group 3. The changes in the group 2 were significantly greater in TUG values, BBS scores, 6MWT values, walking speed, and cadence than those of the group 3. Conclusion: The result of this study show inclined treadmill gait training with RAS is more effective to improve balance and gait in stoke patients than inclined treadmill or general treadmill gait training without RAS.

• Journal of Convergence for Information Technology
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• v.9 no.10
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• pp.220-226
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• 2019

Transcutaneous electrical nerve stimulation and interferential current therapy were applied to the plantar flexor of the stroke patients, and the immediately effects on gait and ankle ROM were investigated. TENS group (n=15) and ICT group (n=15) were applied to the paretic side plantar flexor, respectively. After 60 minutes of application, evaluation of the gait and passive ankle dorsiflexion range of motion (ROM) using smartphone. After 60 minutes of application, immediate post evaluation was carried out. Two electrotherapy methods showed a significant increase in gait speed, cadence, and ankle ROM. Two electrotherapy methods were intervention methods that could increase the gait and ankle ROM of stroke patients. More subjects will be needed to pinpoint differences between the two electrotherapy methods.

• Journal of the Korean Ceramic Society
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• v.29 no.2
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• pp.136-142
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• 1992

The effects of cyclic stress, frequency and bias-pressure on densification of Al2O3 powder cyclic compaction are investigated. The effect of frequency was not significant on densification of Al2O3 powder under cyclic compaction. The higher the cyclic stress and the lower the bias pressure, the higher densification was achieved. To obtain a higher densification, cyclic compaction was more efficient than 1 stroke compaction. A densification equation was proposed to describe an cyclic time dependent pressure-volume relation for Al2O3 powder under cyclic compaction. This equation was obtained empirically, based on the pressure-volume equation proposed by Cooper and Eaton, the time dependent densification equation by Kim and Suh and experimental data for Al2O3 powder under cyclic compaction. The agreement between the proposed equation and experimental data for Al2O3 powder under cyclic compaction was very good.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.12
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• pp.5867-5874
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• 2012

The aim of this study was to find on muscle architectural and tissue compliance of biceps brachii in stroke patient based on elbow joint angle. The subjects of this study were twelve hemiplegic adults after stroke with passive range of motion in the elbow from $10^{\circ}$ to $90^{\circ}$ and Modified Ashworth Scale score 1 to 3 were recruited. Ultrasonography and Myotonometer was used to measure biceps brachii muscle pennation angle, fascicle length, and tissue compliance at the rest condition and pennation angle, fascicle length, and tissue compliance of the biceps brachii muscle were measured in the affected and unaffected sides of people after stroke at 9 different elbow angles ranging from $10^{\circ}$ to $90^{\circ}$ at the rest condition. The results of this study, comparisons found that the pennation angles of the affected biceps brachii muscle were significantly larger(p<.05) than the unaffected muscle in the most extended positions($<40^{\circ}$), whereas the affected fascicle lengths were significantly shorter(p<.05) than the unaffected muscle in most flexed positions($>20^{\circ}$), and the affected tissue compliance were significantly lower(p<.05) than the unaffected muscle in most extended positions($<50^{\circ}$) Therefore, pennation angles, fascicle lengths, and tissue compliance were found to be joint-angle-dependent in both the affected and unaffected sides at the rest condition. Suggest that, the results data can be used as a muscle architectural changes and clinical treatment research in stroke patients.

• Journal of the Korea Convergence Society
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• v.11 no.5
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• pp.87-96
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• 2020

The purpose of this study is to evaluate the convergence effectiveness of treadmill training in patients with chronic stroke through a meta-analysis. After searching the literature based on the patients, intervention, comparison, outcome criteria, and study desigan, a total of 22 studies related to "stroke" and "treadmill" were eligible for inclusion. Effect size was calculated using the comprehensive meta-analysis program for the meta-analysis. Based on the forest plot results, the overall effect size of treadmill training was 0.661 (95% confidence interval: 0.456-0.865), which was statistically significant with a medium effect size (p < 0.05). The effects of treadmill training on patients with stroke were separated by dependent variables of interest-plantar pressure (1.147), lower limb muscle function (0.875), and balance (0.664). The effect sizes were evaluated for the subdomains of timed up and go test (0.553), Berg Balance Scale (0.760), and static balance index (0.654) for balance. Therefore, treadmill training can be expected to have a positive impact on improving the quality of life of patients with chronic stroke. This meta-analysis of treadmill training may the lead to an industry paradigm shift toward healthcare convergence of information, communication, and medical technology.

• Journal of the Korean Society for Precision Engineering
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• v.19 no.12
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• pp.163-170
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• 2002

The quality of a precision product, in general, relies on the accuracy and precision of its manufacturing and inspection process. In many cases, the level of precision in the manufacturing and inspection system is also dependent on the positioning capability of tool with respect to the work piece in the process. Recently the positioning accuracy level has reached to the level of submicron and long range of motion is required. For example, for 1 GDARM lithography, 20nm accuracy and 300mm stroke needs. This paper refers to the lithography stage especially to fine stage. In this study, for long stroke and high accuracy, the dual servo system is proposed. For the coarse actuator, LDM (Linear DC Motor) is used and for fine one VCM is used. In this study, we propose the new structure of VCM for the fine actuator. It is 3 axis precision positioning stage for an aligner system. After we perform the optimal design of the stage to obtain the maximum force, which is related to the acceleration of the stage to accomplish throughput of product. And we controlled this fine stage with TDC. So we obtained 50nm resolution. So later more works will be done to obtain better accuracy.

• Journal of Mechanical Science and Technology
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• v.19 no.2
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• pp.520-528
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• 2005

In this study, a new mathematical dynamic model of displacement sensitive shock absorber (DSSA) is proposed to predict the dynamic characteristics of automotive shock absorber. The performance of shock absorber is directly related to the vehicle behaviors and performance, both for handling and ride comfort. The proposed model of the DSSA has two modes of damping force (i.e. soft and hard) according to the position of piston. In this paper, the performance of the DSSA is analyzed by considering the transient zone for more exact dynamic characteristics. For the mathematical modeling of DSSA, flow continuity equations at the compression and rebound chamber are formulated. And the flow equations at the compression and rebound stroke are formulated, respectively. Also, the flow analysis at the reservoir chamber is carried out. Accordingly, the damping force of the shock absorber is determined by the forces acting on the both side of piston. The analytic result of damping force characteristics are compared with the experimental results to prove the effectiveness. Especially, the effects of displacement sensitive orifice area and the effects of displacement sensitive orifice length on the damping force are observed, respectively. The results reported herein will provide a better understanding of the shock absorber.

• 제어로봇시스템학회:학술대회논문집
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• 1990.10b
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• pp.1184-1189
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• 1990

In order to investigate liquid fuel filming over the intake manifold wall, an electrode-type probe has been developed by lines of authors and this probe was employed in a single cylinder two and four-stroke cycle engine and in a four cylinder four-stroke engine operated by neat methanol fuel. The performance of the probe was dependent upon several parameters including the liquid fuel layer thickness, temperature, additive in the fuel, and electric power source (i.e., AC and voltage level) and was independent of other variables such as direction of liquid flow with respect to the probe arrangement. Several new findings from this study may be in order. The flow velocity of the fuel layer in the intake manifold of engine was about (if the air velocity in the steady state operation, the layer thickness of liquid fuel varied in both the circumferential and longitydinal directions. In the transient operation of the engine, the temporal variation of fuel thickness was determined, which clearly suggests that there was difference between fuel/air ratio in the intake manifold and that in the cylinder. The variation was greatly affected by the engine speed, fuel/air ratio and throttle opening. And the variation was also very significant from cylinder to cylinder and it was particularly strong different engine speeds and throttle opening.