• Progress in Medical Physics
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• v.21 no.2
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• pp.201-208
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• 2010

Recently, along with technology development of endoscopic equipment, a stent has been developed for the convenience of operation, shortening of recovery times, and reduction of patient's pain. To this end, optimal factors are simulated for the stent structure and mechanical reaction and verified using finite element analysis. In order to compare to present commercialized product such as Zilver (Cook, Bloomington, Indiana, USA) and S.M.A.R.T (Cordis, Bridgewater Towsnhip, New Jersey, USA), mechanical impact factors were determined through Taguchi factor analysis, and flexibility and expandability of all the products including ours were tested using finite element analysis. Also, important factors were sought that fulfill the optimal condition using central composition method of response surface analysis, and optimal design were carried out based on the important factors. From the centra composition method of Response surface analysis, it is found that importat factors for flexibility is stent thickness (T) and unit area (W) and those for expandability is stent thickness (T). In results, important factors for optimum condition are 0.17 mm for stent thickness (T) and $0.09\;mm^2$ for unit area (W). Determined and verified by finite element analysis in out research institute, a stent was manufactured and tested with the results of better flexibility and expandability in optimal condition compared to other products. Recently, As Finite element analysis stent mechanical property assessment for research much proceed. But time and reduce expenses research rarely stent of optimum coditions. In this research, Important factor as mechanical impact factor stent Taguchi factor analysis arrangement to find flexibility with expansibility as Finite element analysis. Also, Using to Center composition method of Response surface method appropriate optimized condition searching for important factor, these considering had design optimized. Production stent time and reduce expenses was able to do the more coincide with optimum conditions. These kind of things as application plan industry of stent development period of time and reduce expenses etc. be of help to many economic development.

• Journal of Physiology & Pathology in Korean Medicine
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• v.21 no.1
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• pp.145-152
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• 2007

Following CNS injury, inhibitory influences at the site of axonal damage occur. Glial cells become reactive and form a glial scar, gliosis. Astrocyte-rich gliosis relates with up-regulation of GFAP and CD81, and eventually becomes physical and mechanical barrier to axonal regeneration. It is postulated that the astrocytic reaction is absent, regeneration of axons can occur. And it was reported that treatment with anti CD81 antibodies enhanced functional recovery in the rat with spinal cord injury. So in this current study, the author investigated the effect of the water extract of Persicae Semen on the regulation of GFAP and CD81 that increase when gliosis occurs. Persicae Semen decreased the expression of GFAP and CD81 in astrocyte cell by ELISA method. Persicae Semen decreased the RNA expression of CD81 and GFAP. The proteins that separate in whole cell were analaysed by western blot, and the expression of GFAP and CD81 was decreased. In vivo, rats brains were peformed cortical stab wound, the water extracts of Persicae Semen were injected for 7 days, 30 days. As a result, GFAP and CD81 expression were decreased in immunohistochemistry. These findings demonstrate that Persicae Semen decreases GFAP and CD81 expression. Accordingly, Persicae Semen could be a candidate for promotion of axon regeneration after CNS injury.

• Journal of rehabilitation welfare engineering & assistive technology
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• v.7 no.2
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• pp.47-54
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• 2013

In this paper, we present an inertial sensor-based motion capturing system to measure and analyze whole body movements. This system implements a wireless AHRS(attitude heading reference system) we developed using a combination of rate gyroscope, accelerometer and magnetometer sensor signals. Several AHRS modules mounted on segments of the patient's body provide the quaternions representing the patient segments's orientation in space. We performed 3D motion capture using the quaternion data calculated. And a method is also proposed for calculating three-dimensional inter-segment joint angle which is an important bio-mechanical measure for a variety of applications related to rehabilitation. To evaluate the performance of our AHRS module, the Vicon motion capture system, which offers millimeter resolution of 3D spatial displacements and orientations, is used as a reference. The evaluation resulted in a RMSE of 2.56 degree. The results suggest that our system will provide an in-depth insight into the effectiveness, appropriate level of care, and feedback of the rehabilitation process by performing real-time limbs or gait analysis during the post-stroke recovery process.

• Journal of Power Electronics
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• v.15 no.3
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• pp.621-633
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• 2015

This paper proposes the analysis and design of a DC-side symmetrical zero-current-switching (ZCS) Class-D current-source driven resonant rectifier to improve the low power-factor and high line current harmonic distortion of lighting applications. An analysis of the junction capacitance effect of Class-D ZCS rectifier diodes, which has a significant impact on line current harmonic distortion, is discussed in this paper. The design procedure is based on the principle of the symmetrical Class-D ZCS rectifier, which ensures more accurate results and provides a more systematic and feasible analysis methodology. Improvement in the power quality is achieved by using the output characteristics of the DC-side Class-D ZCS rectifier, which is inserted between the front-end bridge-rectifier and the bulk-filter capacitor. By using this symmetrical topology, the conduction angle of the bridge-rectifier diode current is increased and the low line harmonic distortion and power-factor near unity were naturally achieved. The peak and ripple values of the line current are also reduced, which allows for a reduced filter-inductor volume of the electromagnetic interference (EMI) filter. In addition, low-cost standard-recovery diodes can be employed as a bridge-rectifier. The validity of the theoretical analysis is confirmed by simulation and experimental results.

• Applied Chemistry for Engineering
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• v.26 no.3
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• pp.326-330
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• 2015

Polymeric membranes have been used in various applications and generally applied to the systems prevented from exterior exposure. However, polymer membranes for outdoor usages such as, an air quality monitoring and membrane reservoirs for the selective recovery of useful metals from seawater, have been newly developed. Thus it is required to investigate the properties of the membrane for the outdoor use and also studies of the accelerated UV exposure onto the polymeric membranes are essential to estimate their weatherability. Herein, we report on the thermal and mechanical properties, morphology changes, and color differences of the polysulfone anisotropic membranes and non-woven type polypropylene membranes with the accelerated UV exposure. Results showed that the effect of UV exposure on the membrane depend not only on the polymer used but also on the form of the membrane. This work can provide some of key informations of the membrane for outdoor use.

• Tunnel and Underground Space
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• v.24 no.6
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• pp.440-448
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• 2014

Hydraulic fracturing technique has been applied in various fields in order to improve the recovery of energy resources such as gas, oil and geothermal energy and research about finding out hydraulic fracturing mechanism and application has been steadily proceeded. In this study, for effective hydraulic fracturing, a scale modeling was progressed to simulate similarly with the actual site. In order to analyze the development aspect of surface crack initiation pressure during hydraulic fracturing followed by different conditions, the number of guide holes hydraulic fracturing test was carried out by setting up a hydraulic fracturing test equipment. Also, through the result, we tried to derive reliable results by comparing and analyzing the value of numerical modeling which is obtained based on the physical properties and mechanical properties with 3DEC, a three-dimensional discrete element method program. As a result, it is considered possible to generate effective crack using the guide hole.

• The Journal of the Acoustical Society of Korea
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• v.32 no.1
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• pp.43-55
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• 2013

The window ventilation system based on the heat recovery device was developed which make air ventilation possible without opening the windows. However, mechanical and aerodynamic noises were come to pass which annoyed people in rooms. In the present study, noise of new window ventilation system was measured in both general room and anechoic chamber. Also, the noise path was detected to find cause of noise generation and vulnerable area of the device. Sound absorptive and insulation materials were applied to mitigate the noise. Finally, an alternative noise control method was suggested which can satisfy with the indoor noise standards. As a result, it was shown that the cause of noise was the low transmission loss in the ventilation system. As a result, it was shown that the main noise source of the ventilation system was the blower and the major cause of noise was the low transmission loss of the ventilation system. It is also concluded that the noise levels complies with the noise standards of 40 dBA when 2 mm rubber sheet is applied inside the ventilation system.

• Transactions of Materials Processing
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• v.14 no.4 s.76
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• pp.384-391
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• 2005

The nickel-based alloy Nimonic 80A possesses the excellent strength, and the resistance against corrosion, creep and oxidation at high temperature. Its products are used in aerospace engineering, marine engineering and power generation, etc. Control of forging parameters such as strain, strain rate, temperature and holding time is important because change of the microstructure in hot working affects the mechanical properties. Change of the microstructure evolves by recovery, recrystallization and grain growth phenomena. The dynamic recrystallization evolution has been studied in the temperature range of $950\~1250^{\circ}C$ and strain rate range of $0.05\~5s^{-1}$ using hot compression tests. The metadynamic recrystallization and grain growth evolution has been studied in the temperature range of $950\~1250^{\circ}C$ and strain rate range $0.05,\;5s^{-1}$, holding time range of 5, 10, 100, 600 sec using hot compression tests. Modeling equations are proposed to represent the flow curve, recrystallized grain size, recrystallized fraction and grain growth phenomena by various tests. Parameters in modeling equations are expressed as a function of the Zener-Hollomon parameter. The modeling equation for grain growth is expressed as a function of the initial grain size and holding time. The modeling equations developed were combined with thermo-viscoplastic finite element modeling to predict the microstructure change evolution during hot forging process. The grain size predicted from FE simulation results is compared with results obtained in field product.

• The Journal of Korean Academy of Prosthodontics
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• v.14 no.1
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• pp.47-54
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• 1976

Pulpal temperature is changed in response for various conditions which were mechanical, thermal, chemical and biological stimuli. This study was performed to determine the pulpal temperature changes which were using air turbine with air-water coolant, water coolant, and conventional dental engine with water coolant and no coolant on 28 canine of dogs. In order to record pulpal temperature, pulp chamber was opened on the labiocervical area of canine. Thermocouple was inserted into pulp chamber and was fixed with filling material(dycal). Changes of pulpal temperature were recorded on the physiograph, which had been standardized temperature degree, through thermocouple to thermistor bridge and carrier preamplifier. The amount of experimental temperature change to that of control was interpreted in the pulpal cavity. The obtained results were as followings: 1. The mean normal temperature was 33.07 centigrade. 2. The temperature was decreased than normal pulpal temperature. It was 12.04 centigrade in reduction by air turbine with air-water coolant, 7.17 centigrade in reduction by air turbine with air coolant, 5.54 centigrade in reduction by conventional engine with water coolant, and 1.26 centigrade in reduction by conventional engine with no coolant. 3. The time for maximal temperature change was 53.3 seconds in reduction by air turbine with air-water coolant, 73.4 seconds in reduction by air turbine with air coolant, 50.9 seconds in reduction by conventional engine with water coolant, and 27.1 seconds in reduction by conventional engine with no coolant. 4.. After reduction was ceased, the recovery time to normal pulp temperature was 287.1 seconds in air turbine with air-water coolant, 189.0 seconds in air turbine with air coolant, 86.9 seconds in conventional engine with water coolant, and 52.9 seconds in conventional engine with no coolant respectively.

• Journal of Advanced Marine Engineering and Technology
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• v.35 no.6
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• pp.757-764
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• 2011

In this study, we analysed the influence of the performance and inflow flow of a radial inflow turbine with the variation of vane nozzle exit angles for a 100kW class turbine applicable in the waste heat recovery system. For this, three-dimensional CFD analysis was performed using commercial code called ANSYS Fluent 12.1. As the vane nozzle exit angle was more increased the reattachment region near blades of the vane nozzle got smaller, and also the Mach number at vane nozzle exit was observed to be 1 due to the effect of the cross section reduction. Through this study, we expect that the analysed results will be used as the design material for the composition of the turbine optimal design parameters corresponding to the target output power.