• Journal of international Conference on Electrical Machines and Systems
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• v.2 no.3
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• pp.295-299
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• 2013

This paper presents the new structure of a spindle motor for hard disk drive (HDD). It can produce axial force as well as torque without a pulling plate or a pulling magnet required for the normal operation of a hydrodynamic bearing in rotating-shaft structure. The proposed models have different air gap length along the axial direction by changing the thickness of permanent magnet (PM). One has a single slope and the other has double slopes on the surface of PM. For the design of the proposed models, variables are defined and its effects on the motor performances are investigated by 3-demensional finite element analysis (FEA). The equi-performance curves are investigated for the main characteristics of the spindle motor such as generated torque, axial force and torque ripple ratio. The validity of the proposed models is verified by the feasibility study and performance evaluation.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.1160-1165
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• 2004

The purpose of this study was to calculate three dimensional angular displacements, moments and joint reaction forces of the ankle joint during the waist pulling, and to assess the ankle joint reaction forces according to different perturbation modes and different levels of perturbation magnitude. Ankle joint model was assumed 3-D ball and socket joint which is capable of three rotational movements. We used 6 cameras, force plate and waist pulling system. Two different waist pulling systems were adopted for forward sway with three magnitudes each. From motion data and ground reaction forces, we could calculate 3-D angular displacements, moments and joint reaction forces during the recovery of postural balance control. From the experiment using falling mass perturbation, joint moments were larger than those from the experiment using air cylinder pulling system with milder perturbation. However, JRF were similar nevertheless the difference in joint moment. From this finding, we could conjecture that the human body employs different strategies to protect joints by decreasing joint reaction forces, like using the joint movement of flexion or extension or compensating joint reaction force with surrounding soft tissues. Therefore, biomechanical analysis of human ankle joint presented in this study is considered useful for understanding balance control and ankle injury mechanism.

• Advances in concrete construction
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• v.11 no.1
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• pp.33-43
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• 2021

A new type of composite insulated concrete sandwich wall (ICS-wall), which is composed of a triangle truss steel wire network, an insulating layer, and internal and external concrete layers, is proposed. To study the mechanical properties of this new ICS-wall, tensile, compression, and shearing tests were performed on 22 specimens and tensile strength and corrosion resistance tests on 6 triangle truss joints. The variables in these tests mainly include the insulating plate material, the thickness of the insulating plate, the vertical distance of the triangle truss framework, the triangle truss layout, and the connecting mode between the triangle truss and wall and the material of the triangle truss. Moreover, the failure mode, mechanical properties, and bearing capacity of the wall under tensile, shearing, and compression conditions were analyzed. Research results demonstrate that the concrete and insulating layer of the ICS-wall are pulling out, which is the main failure mode under tensile conditions. The ICS-wall, which uses a graphite polystyrene plate as the insulating layer, shows better tensile properties than the wall with an ordinary polystyrene plate. The tensile strength and bearing capacity of the wall can be improved effectively by strengthening the triangle truss connection and shortening the vertical distances of the triangle truss. The compression capacity of the wall is mainly determined by the compression capacity of concrete, and the bonding strength between the wall and the insulating plate is the main influencing factor of the shearing capacity of the wall. According to the tensile strength and corrosion resistance tests of Austenitic stainless steel, the bearing capacity of the triangle truss does not decrease after corrosion, indicating good corrosion resistance.

• Journal of Biosystems Engineering
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• v.30 no.4 s.111
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• pp.229-234
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• 2005

Kinetic friction coefficient, bulk density, dynamic and static angle of repose, and terminal velocity of rice husk at the moisture range 7 to $23\%$ w.b. were determined. It could lead to better design and operation of the processing machinery and handling facilities. Friction coefficient was determined from the horizontal traction force measured by pulling the container holding a mass of rice husk on various plate materials. Dynamic angle of repose was calculated from the photos of bulk samples piled by gravity flow on a circular platform. Static angle of repose was determined by measuring the side angle of the bulk material which was left in a cylindrical container after natural discharge of the bulk sample through a circular hole in the bottom plate. Kinetic friction coefficients of rice husk were in the range of $0.254\~0.410,\;0.205\~0.520,\;0.229\~0.400,\;and 0.133\~0.420$ on PVC, mild steel, galvanized steel, and stainless steel, respectively. Bulk density, dynamic and static angle of repose, and terminal velocity were in the range of $91.7\~98.3$ $kg/m^3$, $40.2\~47.6^{\circ},\;52.8\~83.7^{\circ},$ and $1.36\~1.73$ m/s, respectively. These physical properties of rice husk increased linearly as the moisture content increased.

• Journal of Biosystems Engineering
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• v.23 no.6
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• pp.583-590
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• 1998

This study was performed to determine the kinetic friction coefficient bulk density, dynamic and static angle of repose, and terminal velocity of the chopped rice straw in the moisture range of 8~23%, which could be used for better design and operation of the processing machinery and handling facilities. Friction coefficient was determined from the horizontal traction force measured by pulling the container holding the mass of rice straw on the various plate materials. Bulk density was measured with an apparatus consisting of a filling funnel and a receiving vessel. Dynamic angle of repose was calculated from the photos of bulk samples piled by gravity flow on a circular platform. Static angle of repose was determined by measuring the side angle of the bulk material which was left in the cylindrical container after natural discharge of the bulk sample through a circular hole in the bottom plate. Kinetic friction coefficients of rice straw on the PVC, mild steel, stainless steel, and galvanized steel were in the range of 0.303~0.434, 0.222~0.439, 0.204~0.448, and 0.206~0.407, respectively. and indicated linear increase with moisture content. The effects of moisture change on the friction coefficients were in the order of PVC, mild steel, galvanized steel, and stainless steel. Bulk density, dynamic and static angle of repose, and terminal velocity were in the range of 56.8~60.3 kg/m$^3$, 41.4~45.9$^{\circ}$, 94.4~100.8$^{\circ}$, and 1.07~4.48 m/s, respectively, and were increased linearly with the moisture content.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.6
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• pp.1031-1034
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• 2007

Electric transmission lines pass through a variety of area. Foundation supporting the conductors and tower are selected properly in accordance with external load, for example dead load, wind load, snow load, construction load etc, and topography and geology condition. Typical types of foundation are as follows: pad foundation for small load and hard soil or rock in mountainous area, pile foundation for medium or large load and soft soil in plain field area. This paper introduced cylindrical foundation design & construction for large load and mountainous area. This foundation failure mode against pulling-out show splitting failure by tensile force toward circumferential direction.

• Korean Journal of Crystallography
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• v.9 no.1
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• pp.21-29
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• 1998

The rare-earth orthoborate family, RM3(BO3)4 is known to be the most promising material for the microlaser host. To grow LaSc3(BO3)4 single crystal, the phase relation of the system LaBO3-ScBO3 was investigated by DTA method. LaSc(BO3)4 was the unique intermediate compound in the binary system the peritectic reaction point of which was 1495 ±2℃. Owing to the peritectic behavior of the compound, the crystal growth of the rare-earth Sc-borate was carried out by pulling from the melt-soultion of La1+xSc3-x(BO3)4. The optimal conditions for the growth of LaSc3(BO3)4 were determined by traditional CZ method : pulling speed 0.7mm/hr, rotation speed 7-10 rpm under reduction condition. Pt and Ir crucibles could be used for about 8-10 times of growth. The effect of thermal configurations on the temperature distribution was investigated. A special two-coordinate manipulator was made for the precise movement of thermocouples from the melt to the top of the furnace for several thermal configurations. The radial gradient on the melt surface depends strongly on the construction of the afterheater. On the other hand, the axial gradient was mainly propotional to both the opening degree of baffle plate and the mutual positions of crucible and heater.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.1 no.1
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• pp.26-38
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• 1991

The fundamental conditions for growing $r-6Bi_2O_3{\cdot}SiO_2$(BSO) single crystal plates by EFG(Edge-defined Film-fed Growth) method, were investigated and characterization, quality test, property measurement were performed for obtained BSO single crystal plates. The opti$\mu$ growing conditions determined in this study were as follows: ${\cdot}$temperature gradient;$24^{\circ}C/cm$ ${\cdot}$pulling rate;2.0mm/h. BSO Single crystal plates grown at the above optimum conditions did not include secondary phase or grain boundary and were confirmed as single crystals by X-ray analysis. IT was found that the single crystal plates had <100> growth direction. G defects, ie pore, void inclusion, striation, were not detected in the single crystal plate under polarizing microscope but dislocations(microscopic defect) were found and dislocation density was $5.1\times10^5/cm^2$.

• Korean Journal of Applied Biomechanics
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• v.23 no.3
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• pp.209-218
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• 2013

This study was to perform the kinetic analysis of forward $1\frac{1}{2}$ somersault on the platform diving. Six men's diving players of the Korea national reserve athletes participated in this study. The variables were analyzed response time, velocity, center of mass (COM), angle, center of pressure (COP) and ground reaction force (GRF) of motion. For measure and analysis of this study, used to synchronized to 4 camcorder and 1 force plate, used to the Kwon3D XP (Ver. 4.0, Visol, Korea) and Kwon GRF (Ver. 2.0, Visol, Korea) for analyzed of variables. The results were as follows; Time factor were observed in maximum knee flexion depending on the extent of use at phase 1 of take-off to execute the somersault. This enabled the subject to secure the highest possible body position in space at the moment of jumping to execute the somersault and prepare for the entry into the water with more ease. Regarding the displacement of COM, all subjects showed rightward movement in the lateral displacement during technical execution. Changes in forward and downward movements were observed in the horizontal and vertical displacements, respectively. In terms of angular shift, the shoulder joint angle tended to decrease on average, and the elbow joints showed gradually increasing angles. This finding can be explained by the shift of the coordinate points of body segments around the rotational axis in order to execute the half-bending movement that can be implemented by pulling the lower limb segments toward the trunk using the upper limb segments. The hip joint angles gradually decreased; this accelerated the rotational movement by narrowing the distance to the trunk. Movement-specific shifts in the COP occurred in the front of and vertical directions. Regarding the changes in GRF, which is influenced by the strong compressive load exerted by the supporting feet, efficient aerial movements were executed through a vertical jump, with no energy lost to the lateral GRF.

• Journal of Korean Physical Therapy Science
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• v.29 no.1
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• pp.41-46
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• 2022

Background: The purpose of this study was to develop a sit-to-stand transfer assistive device, and to conduct a feasibility test. Design: A technical note. Methods and results: In this study, we developed a sit-to-stand transfer assistive device for the elderly and the disabled who have difficulty standing up independently from sitting positions. The sit-to-stand transfer assistive device allows the user to transfer the weight from a sitting position to a standing position while shifting the weight forward by grabbing and pulling a support stand. Ten healthy adults participated in the feasibility test of the device. Each participant used the developed sit-to-stand transfer assistive device and investigated supplementation through a brief interview. As a result of the feasibility test, the opinion was that the device could assist the sit-to-stand transfer to some extent. There were opinions that it needed a function to adjust the height of the knee protective plate in the sitting position according to the user's physical characteristics. Because of the inconvenience of operating the lock device for fixing the position and adjusting inclination, there was an opinion that the improvement for a locking device is needed. There were opinions that it would be better to reduce the size of the device due to its inconvenience of portability. Conclusion: In this study, we developed the sit-to-stand transfer assistive device for the elderly and the disabled who have difficulty standing up independently from sitting positions. In addition, it is considered that the upgrade of the device is necessary for the future since there are supplementary opinions on some points.