• Physical Therapy Korea
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• v.28 no.2
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• pp.108-116
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• 2021

Background: Whole-body vibration (WBV) has been used to alleviate proprioceptive damage by musculoskeletal and neurological conditions. However, no study has determined whether wearing shoes while applying WBV can affect proprioception precision of the knee joint. Objects: This study aimed to determine the differences in the proprioceptive precision of the knee joint before and after WBV and to compare the proprioceptive precision of the knee joint between barefoot and shoe-wearing conditions. Methods: This study recruited 33 healthy participants. A passive-to-active angle reproduction test was used to measure the proprioception precision of the knee joint using an electrogoniometer, and the target angle was set to a knee flexion of 30°. Proprioception precision was calculated using the error angle (angular difference from 30°). Proprioceptive precision was measured in weight-bearing and non-weight-bearing positions before and after applying WBV for 20 minutes at 12 Hz in barefoot and shoe-wearing conditions. Mixed repeated analysis of variance was used to determine the differences in changes in the proprioceptive precision of the knee joint according to foot conditions. Results: There were significant improvements in the weight-bearing (p = 0.002) and non-weight-bearing (p < 0.001) proprioceptive precision of the knee joint after applying WBV. However, there was no significant difference in the change in proprioceptive precision of the knee joint after applying WBV between the barefoot and shoe-wearing conditions. Conclusion: WBV stimulation had an immediate effect on improving the proprioceptive precision of the knee joint. However, foot conditions (barefoot or shoe-wearing) during WBV application did not influence the proprioceptive precision of the knee joint.

• Transactions of the Korean Society of Mechanical Engineers
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• v.12 no.4
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• pp.721-729
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• 1988

Recently, the precision required by precision manufacturing and machinery related to electronics is within the domain of submicron that it is difficult to evaluate them by traditional measuring equipments and methods. Accordingly, precision of sub 0.1.mu.m super precise position-decision-apparatus and straight-guide air bearing have been researched and they are almost ready to be used. In utilizing straight-guide-table for super-precision-measurement which used externally pressurized porous air bearing as a way of externally pressurized air bearing, the high-precision-straight movement is the most crucial. In this study, the researcher conducted the experimental study with trial manufacture to see how the surrounding temperature and support condition influenced the selection and allocation of the machine composing element which is important to the high-precision-straight movement. The researcher finding showed that when the property of the rail part and support part of the semi-closed slider form is different, the heat generation of the working motor and surrounding temperature influence the high-precision-straight movement significantly and the researcher showed the influence of the condition of central load and eccentric load to the straight movement precision when the support stand of the straight-table was supported by numerical values.

• Journal of the Korean Society for Precision Engineering
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• v.27 no.5
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• pp.22-26
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• 2010

Recently, due to the tremendous growth of media technology, demands of the aspheric glass lens which is a high-performance and miniaturized increase gradually. Generally, the aspheric glass lens is manufactured by Glass Molding Press (GMP) method using tungsten carbide (WC) mold core. In this study, the thermal deformation which was occurred by GMP process was analyzed and applied it to compensate the aspheric glass lens. The compensated lens was satisfied that can be applied to the actual specifications.

• Journal of the Korean Society for Precision Engineering
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• v.27 no.7
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• pp.94-100
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• 2010

This paper describes the design and evaluation procedure of an ultra-precision rotary table for freeform generating machined tools. Design of the thrust and journal hydrostatic bearings and experimental evaluation of the table were performed. To get the compact size and less lost motion direct drive servomotor with ultra precision encoder. From the considered design, following performance were confirmed by experiment. The total stiffness of the prototype rotary table was 483.6 $N/{\mu}m$ and 97.6 $N/{\mu}m$ for axial and radial direction, respectively. Rotational accuracy of the table was investigated by capacitive sensor and reversal measurement technique, and 0.10 ${\mu}m$ radial direction and 0.05 ${\mu}m$ axial direction of the rotational accuracy were confirmed. The micro resolution of the table was also investigated with displacement of capacitive sensor, and $0.5/10000^{\circ}$ of micro resolution was confirmed. Index accuracy of the table was evaluated by the autocollimator and polygon mirror, and the $\pm0.39$ arcsec accuracy and $\pm0.16$ arcsec repeatability of the table were confirmed. Those are under the general requirements of ultra precision rotary tables for freeform generating machined tools.

• Journal of Astronomy and Space Sciences
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• v.35 no.4
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• pp.243-252
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• 2018

In a satellite gravimetry mission similar to GRACE, the precision of inter-satellite ranging is one of the key factors affecting the quality of gravity field recovery. In this paper, the impact of ranging precision on the accuracy of recovered geopotential coefficients is analyzed. Simulated precise orbit determination (POD) data and inter-satellite range data of formation-flying satellites containing white noise were generated, and geopotential coefficients were recovered from these simulated data sets using the crude acceleration approach. The accuracy of the recovered coefficients was quantitatively compared between data sets encompassing different ranging precisions. From this analysis, a rough prediction of the accuracy of geopotential coefficients could be obtained from the hypothetical mission. For a given POD precision, a ranging measurement precision that matches the POD precision was determined. Since the purpose of adopting inter-satellite ranging in a gravimetry mission is to overcome the imprecision of determining orbits, ranging measurements should be more precise than POD. For that reason, it can be concluded that this critical ranging precision matching the POD precision can serve as the minimum precision requirement for an on-board ranging device. Although the result obtained herein is about a very particular case, this methodology can also be applied in cases where different parameters are used.

• Research in Mathematical Education
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• v.25 no.4
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• pp.267-284
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• 2022

In response to the current educational situation of students' heavy workload, the author constructs the precision-targeted classroom based on Precision Teaching (PT), Network Pharmacology, and Treatment Based on Syndrome Differentiation. The precision-targeted classroom can solve the current problems of PT and the phenomenon of the heavy academic burden on students, achieve the reduction of the burden and increase the efficiency of education. The precision-targeted classroom includes five key points: targeted goals, childlike thinking, precise intervention, intelligent homework, and stereoscopic evaluation, and the implementation process of the precision-targeted classroom is built from three aspects: before, during and after class. In addition, the author applied it to the actual mathematics classroom to test its teaching effect, and the experimental results showed that: the precision-targeted classroom significantly improved students' academic performance and thinking level; considerably improved students' classroom learning status, and facilitated teaching personalization and realized homework quantity control and quality improvement.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.4 no.5
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• pp.1143-1150
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• 2000

A dual-mode multiplier (DMM) that performs single- and double-precision multiplications has been designed using a $0.25-\mum$ 5-metal CMOS technology. An algorithm for efficiently implementing double-precision multiplication with a single-precision multiplier was proposed, which is based on partitioning double-precision multiplication into four single-precision sub-multiplications and computing them with sequential accumulations. When compared with conventional double-precision multipliers, our approach reduces the hardware complexity by about one third resulting in small silicon area and low-power dissipation at the expense of increased latency and throughput cycles. The DMM consists of a $28-b\times28-b$ single-precision multiplier designed using radix-4 Booth receding and redundant binary (RB) arithmetic, an accumulator and a simple control logic for mode selection. It contains about 25,000 transistors on the area of about $0.77\times0.40-m^2$. The HSPICE simulation results show that the DMM core can safely operate with 200-MHZ clock at 2.5-V, and its estimated power dissipation is about 130-㎽ at double-precision mode.

• Journal of the Korean Society for Precision Engineering
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• v.21 no.8
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• pp.27-33
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• 2004

The ultra-precision cutting is a key technique for the manufacture of optical components such as aluminium mirrors, electroless nickel mirror, plastic mirror in a variety of advanced science and technology applications. The paper presents experimental results of ultra-precision diamond fuming of electroless nickel materials. In general, the cutting condition such as feed rate and depth of rut, have effect on the surface roughness in ultra-precision diamond turning. To obtain an optimal cutting condition, we studied the effect of the cutting speed. the tool length, the tool nose radius, the feed rate and depth of cut on the surface roughness. So, the relationship of the surface roughness and cutting condition has been clarified. From the experimental results, the machined surface roughnesses were obtained less than 1nm rms.

• Journal of the Korean Society of Safety
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• v.18 no.1
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• pp.94-100
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• 2003

Generally, cable-stayed bridges are both statically indeterminate structure with a high degree of redundancy and flexible structure. So it is very important to ensure precision control during both fabrication and construction. In precision control of cable-stayed bridges, precision control under multi-objective programming method is needed, because precision control problem of cable-stayed bridges is a multi-objective programming problem in which many objective functions are regard as variables. In previous studies, it was regarded as a single-objective problem, so it had many problems in respect of usefulness and rationalness. In this study, precision control under multi-objective programming method is proposed considering economy, efficiency, and safety at best in precision control of cable-stayed bridges. Precision control problem of cable-stayed bridges is formulated with satisfying trade-off method which is a kind of multi-objective programming method, then it is optimized with min-max method. A computer program is presented including above process.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.10a
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• pp.437-441
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• 1995

In this paper, the ultra precision positioning system for servo motor and piezo actuator using dual servo loop control has been developed. For positioning system having long distance with ultra precision, the combination of global stage and micro stage is required. Servo moter and ball screw are used as a master stage and piezo acuator as a fine stage. By using this system, an positional precision witin .+-. 30nm has been achieved at dual servo loop control. When using micro stage, an positional precision within .+-. 10nm has been achieved. This result can be applied to develop semiconductor equipment such as wafer stepper.