• The Journal of Korean Physical Therapy
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• v.32 no.6
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• pp.335-340
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• 2020

Purpose: This study was performed to investigate the influence of the condition with and without external support on the strength of hip flexor in supine position in subjects without core stabilization. Hip flexor muscles are very functional in the hip joint structures. Therefore, it is essential to evaluate the strength of hip flexor in a clinical and precise way. Methods: Twenty subjects participated in this study. The double bent leg-lower test was used to evaluate subjects without core stabilization. The strength of hip flexor muscles was evaluated in supine position, both with and without external support condition. The paired t-test was used to compare the strength of hip flexor muscles according to external support. The level of statistical significance was at α=0.05. The intra-rater reliability of the repeated measures of hip flexor strength was estimated by calculating the intra-class correlation coefficients (ICC). Results: In subjects without core stabilization, the strength of hip flexor in supine was greater with external support than that without external support (p<0.05). In addition, the intra-rater reliability with an ICC (3, 1) of the strength measurement of hip flexor with external support was higher than that without external support. Conclusion: In subjects without core stabilization, the condition with external support can contribute to the strength of hip flexor in supine position and the strength measurement of hip flexor should be considered with the condition with and without external support.

• Journal of the Korean Society of Industry Convergence
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• v.3 no.3
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• pp.201-207
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• 2000

In this study, methodologies for checking the interference between in-core instrumentation (ICI) guide tubes for routing of ICI guide tubes in the reactor coolant system of typical Pressurized Water Reactor under cold and normal operation (NOP) conditions are presented. The closest points of ICI guide tubes under cold condition are calculated by using minimize technique and are used as data for NOP analysis. Movements of ICI guide tubes under NOP condition are performed by the commercial computer code, SUPERPIPE.

• Journal of Mechanical Science and Technology
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• v.18 no.12
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• pp.2125-2136
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• 2004

In this paper, a numerical application algorithm for applying the CFAM (Consistent Fluid Added Mass) matrix for a core seismic analysis is developed and applied to the 7-ducts core system to investigate the fluid effects on the dynamic characteristics and the seismic time history responses. To this end, three cases such as the in-air condition, the in-water condition without the fluid coupling terms, and the in-water condition with the fluid coupling terms are considered in this paper. From modal analysis, the core duct assemblies revealed strongly coupled out-of-phase vibration modes unlike the other cases with the fluid coupling terms considered. From the results of the seismic time history analysis, it was also verified that the fluid coupling terms in the CFAM matrix can significantly affect the impact responses and the seismic displacement responses of the ducts.

• The Journal of Korean Physical Therapy
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• v.28 no.3
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• pp.195-200
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• 2016

Purpose: This study was designed to evaluate the effects of the different condition of leg support surface on the upper extremity and core muscle activity during the push-up exercise. Methods: Fifteen healthy subjects that were practicable push-ups were recruited in this study. Subjects were instructed the push-up exercise in the different condition of the leg support surface. Each condition of support surface was set to the high and lower, and the unstable and stable condition. Muscle activation was measured by using the surface electromyography (EMG), and recorded from the triceps brachii, serratus anterior, latissimus dorsi, rectus abdominis, abdominal external oblique, and erector spinea muscle. Results: In the results of experiments, there was no significant difference of muscle activation in upper extremity between the high unstable and high stable support surface. By contrast, muscle activation of the rectus abdominis and abdominal external oblique was significantly higher in the low unstable support surface, compared with those of the low stable support surface. It is well known that the core muscle was important to stabilization of trunk stability. Conclusion: This result demonstrates that the low and unstable support surface for the lower extremity was suited for training of core muscle for trunk stabilization during the push-up exercise.

• The KSFM Journal of Fluid Machinery
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• v.17 no.6
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• pp.104-108
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• 2014

The recent Fukushima nuclear power plant accidents shows that the core make up at high RCS pressure condition is very important to prevent core melting. The core make up flow at high pressure condition should be driven by gravity force or passive forces because the AC-powered safety features are not available during a Station Black Out (SBO) accident. The reactor Coolant System (RCS) mass inventory is continuously decreased by releasing steam through the pressurizer safety valves after reactor trip during a SBO accident. The core will be melted down within 2~3 hours without core make up action by active or passive mode. In the new design concept of a Hybrid Safety Injection Tank (Hybrid SIT) both for low and high RCS pressure conditions, the low pressure nitrogen gas serves as a charging pressure for a LBLOCA injection mode, while the PZR high pressure steam provides an equalizing pressure for a high pressure injection mode such as a SBO accident. After the pressure equalizing process by battery driven initiation valve at a high pressure SBO condition, the Hybrid SIT injection water will be passively injected into the reactor downcomer by gravity head. The SBO simulation by MARS code show that the core makeup injection flow through the Hybrid SIT continued up to the SIT empty condition, and the core heatup is delayed as much.

• Nuclear Engineering and Technology
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• v.51 no.7
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• pp.1738-1748
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• 2019

Previous research has shown that the inclined condition has an impact on the natural circulation (natural circulation) mode operation of Floating Nuclear Power Plant (FNPP) mounted on the movable marine platform. Due to its compact structure, small volume, strong maneuverability, the Integral Pressurized Water Reactor (IPWR) is adopted as marine reactor in general. The OTSGs of IPWR are symmetrically arranged in the annular region between the reactor vessel and core support barrel in this paper. Therefore, many parallel natural circulation loops are built between the core and the OTSGs primary side when the main pump is stopped. and the inclined condition would lead to discrepancies of the natural circulation drive head among the OTSGs in different locations. In addition, the flow rate and temperature nonuniform distribution of the core caused by inclined condition are coupled with the thermal hydraulics parameters maldistribution caused by OTSG group operating mode on low power operation. By means of the RELAP5 codes were modified by adding module calculating the effect of inclined, heaving and rolling condition, the simulation model of IPWR in inclined condition was built. Using the models developed, the influences on natural circulation operation by inclined angle and OTSG position, the transitions between forced circulation (forced circulation) and natural circulation and the effect on natural circulation operation by different OTSG grouping situations in inclined condition were analyzed. It was observed that a larger inclined angle results the temperature of the core outlet is too high and the OTSG superheat steam is insufficient in natural circulation mode operation. In general, the inclined angle is smaller unless the hull is destroyed seriously or the platform overturn in the ocean. In consequence, the results indicated that the IPWR in the movable marine platform in natural circulation mode operation is safety. Selecting an appropriate average temperature setting value or operating the uplifted OTSG group individually is able to reduce the influence on natural circulation flow of IPWR by inclined condition.

• Journal of the Korean Society for Precision Engineering
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• v.27 no.7
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• pp.117-122
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• 2010

Recently, aspheric glass lens molding core is fabricated with tungsten carbide(WC). If molding core is fabricated with silicon carbide(SiC), SiC coating process, which must be carried out before the Diamond-Like Carbon(DLC) coating can be eliminated and thus, manufacturing time and cost can be reduced. Diamond Like Carbon(DLC) is being researched in various fields because of its high hardness, high elasticity, high durability, and chemical stability and is used extensively in several industrial fields. Especially, the DLC coating of the molding core surface used in the fabrication of a glass lens is an important technical field, which affects the improvement of the demolding performance between the lens and molding core during the molding process and the molding core lifetime. Because SiC is a material of high hardness and high brittleness, it can crack or chip during grinding. It is, however, widely used in many fields because of its superior mechanical properties. In this paper, the grinding condition for silicon carbide(SiC) was developed under the grinding condition of tungsten carbide. A silicon carbide molding core was fabricated under this grinding condition. The measurement results of the SiC molding core were as follows: PV of 0.155 ${\mu}m$(apheric surface) and 0.094 ${\mu}m$(plane surface), Ra of 5.3 nm(aspheric surface) and 5.5 nm(plane surface).

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.20 no.9
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• pp.808-811
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• 2007

Aspheric glass lens have recently been used in camera phone module because they are more effective than spherical ones. In this paper, the grinding condition of the tungsten carbide molding core has been found after applying DOE to the development of the aspheric glass lens for the 3 Megapixel and 2.5x camera-phone module. Also, the ultra precision grinding process was investigated under this condition by experiment. Re-Ir coating was applied on the ground surface of the tungsten carbide molding core. The influence of Re-Ir coating on the form accuracy and surface roughness of molding core was compared and evaluated. The form accuracy and surface roughness of the molding core were improved by application of Re-Ir coating on the surface of the tungsten carbide molding core.

• Progress in Superconductivity and Cryogenics
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• v.17 no.2
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• pp.31-35
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• 2015

Mapping is a useful tool in the magnetic field analysis and design. In some specific research area, such as the nuclear magnetic resonance (NMR) or the magnetic resonance imaging (MRI), it is important to map the magnetic field in the interesting space with high accuracy. In this paper, an indirect mapping method in the center volume of an air-core solenoid is presented, based on the solution of the Laplace's equation for the field. Through the mathematical analysis on the mapping calculation, we know that the condition number of the matrix, generated by the measurement points, can greatly affect the error of mapping result. Two different arrangement methods of the measurement points in field mapping are described in this paper: helical cylindrical line (HCL) method and parallel cylindrical line (PCL) method. According to the condition number, the HCL method is recommended to measure the field components using one probe. As a simple example, we mapped the magnetic fields in a MRI main magnet system. Comparing the results in the different methods, it is feasible and convenient to apply the condition number to reduce the error in the field mapping calculation. Finally, some guidelines were presented for the magnetic field mapping in the center volume of the air-core solenoid.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.18 no.1
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• pp.76-82
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• 2009

To obtain the surface roughness with nano order, we need a ultra-precision machine, cutting condition, and materials. In this paper, the cutting condition for getting nano order smooth surface of core have been examined experimentally by the ultra-precision machine and diamond wheels. The effects of the cutting velocity, the feed rate and depth of cut on the surface roughness were studied. And also, the surface roughness was measured by the Form Talysurf series PGI 840. The champion data of developed core was surface roughness Rmax 24.6nm, figure accuracy Rmax 68.9nm.