• International Journal of Precision Engineering and Manufacturing
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• v.8 no.2
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• pp.54-58
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• 2007

This paper describes an atomic force microscope (AFM)-based instrument for measuring the nanoscale cutting edge profiles of diamond cutting tools. The instrument consists of a combined AFM unit and an optical sensor to align the AFM tip with the top of the diamond cutting tool edge over a submicron range. In the optical sensor, a aser beam is emitted from a laser diode along the Y-axis and focused to a small beam spot with a diameter of approximately $10{\mu}m$ at the beam waist, which is then received by a photodiode. The top of the tool edge is first brought into the center of the beam waist by adjusting it in the X-Z-plane while monitoring the variation in the photodiode output. The cutting tool is then withdrawn and its top edge position at the beam center is recorded. The AFM tip can also be positioned at the beam center in a similar manner to align it with the top of the cutting edge. To reduce electronic noise interference on the photodiode output and thereby enhance the alignment accuracy, a technique is applied that can modulate the photodiode output to an AC signal by driving the laser diode with a sinusoidal current. Alignment experiments and edge profile measurements of a diamond cutting tool were carried out to verify the performance of the proposed system.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.28 no.3
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• pp.329-336
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• 2010

This study deals with the measurement of reflectivity as well as the distance accuracy with Terrestrial Laser Scanner(TLS) using time of flight methods and near infrared wave length, for a variety of user-made targets. Especially, point clouds' reflection to several targets was measured with Gretag Macbeth il spectrophotometer in the office. And the distance accuracy in comparison to reference distance for TLS performance evaluation, was tested after scanning the user-made targets and measuring the inter-pillars distances over the precise EDM calibration baseline. The results of test was shown that except white resin objects, with approx. 10m and 170m inter-pillar distances, other targets achieved the distance accuracy of several millimeters(mm) with respect to standard distances. Future work should be concentrate on a few parameters influencing on the distance accuracy such as atmospheric correction, instrument correction, the additive constant or zero/index correction, etc.

• Journal of Periodontal and Implant Science
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• v.27 no.3
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• pp.575-584
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• 1997

The quality of periodontal instrument cutting edge is a basic element of effective root planing procedure. Using instruments, the sharp edge is changed into blunt or beveled edge. With the blunt instrument, the periodontal treatment can't be carried into accuracy and effective. The study on the wear of periodontal curet is insufficient, there are few publications about the change of sharpness of cutting egde after using instrument and a certen reports were published on the study of scanning electron microscope(SEM) examination. In this study, to declare the number of strokes for sharpening of instruments, the changes of cutting edge is measured by the clinical methods, tactile sensitivity examination and refraction light-white line test after scaling strokes and root planing strokes. SEM test was added for defined the changes of cutting edges. The 7/8 Gracey curets that have been never used was tested. Maxillary molars which were extracted from the School of Dental Medicine, Dankook University was used. Subjected teeth had attachment loss more than 6 mm in bucca-lingual surface and sufficient calculus of a band type in cervical area. The strokes of curet were executed 3, 5, 7, 9, 11, 13 times on scaling stroke and 10, 15, 20, 25, 30, 35 times on root planing stroke. A resident has periodontal experience over 3 years carried out the clinical examinations those tactile sensitivity examination and refraction light-white line test 5 times. The case there being tactile sensitivity certenly is 2, the case being felt tactile sensitivity is 1, and the case there not being tactile sensitivity is 0. The visual examination was recorded as following. The case that refracted white line is not recognised is 2, the case that uncerten is 1, and the case that acknowledged is 0. The results were obtained as follows. 1. After scaling strokes, the tactile sensitivity was reduced after 11 strokes and disappeared in 13 strokes. 2. In tactile sensitivity after root planing procedures, sensitivity was reduced after 25 strokes and disappeared in 35 strokes. 3. In case of visual examination, the detection of refracted white line was increased after 9 strokes of scaling procedures and the accuracy of wear wasn't showed after root planing procedures. 4. In SEM, metal projection was observed on new periodontal curet cutting edge and it was disappeared after scaling procedures. 5. In SEM, the cutting edge was showed changing linear into an aspect of the surface after 5 strokes of scaling procedures and 10 strokes of root planing procedures and showed beveled edge in 11 strokes of scaling procedures, 25 strokes of root planing procedures. The results of 3-type examination indicated that the sharpening of curet should be performed after 11 strokes of scaling procedures and 25 strokes of root planing procedures.

• Journal of Music and Human Behavior
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• v.20 no.1
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• pp.75-97
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• 2023

This study aimed to investigate the effect of cognitive-motor interaction-based instrument playing on the early social skills of children with autism spectrum disorder (ASD). Nine children with ASD, averaging 5.6 years of age, participated in twelve individual sessions lasting 30 minutes each. The intervention comprised five stages: self-regulation, motivation to engage in social interaction, acceptance of a partner in co-playing activities, interpersonal coordination with a partner, and engagement in joint music playing. To evaluate changes in early social skills, joint attention and social interaction behaviors were observed, and the Social Responsiveness Scale (SRS-2) was administered pre- and post-intervention. Social synchronization was measured through a dyadic drum task, measuring synchronization accuracy, duration, and timing. Following the intervention, all nine children demonstrated increased early social behaviors, although there were no significant differences in SRS scores. Moreover, synchronized movement improved significantly in accuracy and maintained duration but not in reaction time. This study highlights the significance of recognizing the cognitive-motor interplay as crucial element in facilitating early social skills development in children with ASD.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.34 no.1
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• pp.67-76
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• 2024

Objectives: Direct reading instruments (DRIs) are widely used by industrial hygienists and other experts for preliminary survey and identifying source locations in many industrial fields. Photoionization detectors (PIDs), which are a form of hand-held portable DRIs, have been used for a variety of airborne vaporized chemicals, especially evaporated hydrocarbon solvents. The benefits of PIDs are high sensitivity between each chemical, competitive price, and portability. With the goal of increasing the accuracy of logged PID concentrations, previous studies have performed tests for the assessment of single chemical compounds, not mixtures. The purpose of this preliminary study was to measure mixtures with a PID and charcoal tube at the same time and compare the accuracy between them. Methods: A chamber test was implemented with different mixtures of hydrocarbon chemicals (acetone, isopropyl alcohol, toluene, m-xylene) and levels in the range of 14 to 864 ppm. Three PIDs and charcoal tubes were connected to the chamber and measured the chemical mixtures simultaneously. A comparison of accuracy and the PID group of concentrations with manufacture correction factor (M_CF) and field correction factor (F_CF) applied was performed. Results: The accuracy of the PID concentrations data-logged from the PID did not meet the accuracy criteria except for the mixture level B and C logged from PID No. 2, which was 18% of all tests for meeting accuracy criteria. The mean and standard deviation (SD) of concentration (ppm) of the charcoal tube followed by each mixtures' level were 10.37±0.26, 155.33±5.28, 300.80±11.65, and 774.93±22.65, respectively. When applying F_CF into the PID concentrations, the accuracy increased by nearly 82%. However, in the case of M_CF, none met the accuracy criterion. Between the PID there were differences of logged concentrations. Conclusions: In this preliminary study, the concentration of a logged PID with F_CF applied was a better way to increase accuracy compared to applying M_CF. We suggest that additional research is necessary to consider environmental factors such as temperature and humidity.

• Journal of Korea Society of Industrial Information Systems
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• v.9 no.1
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• pp.56-62
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• 2004

This paper examined the change in reaction time and accuracy of mental work by physical activity. A treadmill-equipped instrument is used to attain several levels of physical activity. Subjects were recruited from college students and football players; and they were instructed to run on a treadmill at different speeds. In order to determine the individual levels of physical activity of subjects, in this paper, Borg's-RPE scales which indicates subjective levels of physical activity were obtained. And reaction time was evaluated before and after running by arithmetic calculation test Restricted within the limit of this experiment, the results of this study showed that arithmetic calculation performance as a scale of accuracy of mental work rather increase after the exercise even though there are slight difference among the subjects.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.40 no.4
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• pp.325-332
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• 2022

Determination of VLBI IVP (Very Long Baseline Interferometry Invariant Point) position with high accuracy is required to compute local tie vectors between the space geodetic techniques. In general, reflective targets are attached on VLBI antenna and slant distances, horizontal and vertical angles are measured from the pillars. Then, adjustment computation is performed by using the mathematical model which connects measurements and unknown parameters. This indicates that the accuracy of the estimated solutions is affected by the accuracy of the measurements. One of issues in local tie surveying, however, is that the reflective targets are not in favorable condition, that is, the reflective sheet target cannot be perfectly aligned to the instrument perpendicularly. Deviation from the line of sight of an instrument may cause different type of measurement errors. This inherent limitation may lead to incorrect stochastic modeling for the measurements in adjustment computation procedures. In this study, error characteristics by measurement types and pillars are analyzed, respectively. The analysis on the studentized residuals is performed after adjustment computation. The normality of the residuals is tested and then equal variance test between the measurement types are performed. The results show that there are differences in variance according to the measurement types. Differences in variance between distances and angle measurements are observed when F-test is performed for the measurements from each pillar. Therefore, more detailed stochastic modeling is required for optimal solutions, especially in local tie survey.

• Journal of Astronomy and Space Sciences
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• v.32 no.4
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• pp.419-425
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• 2015

In this study, a new idea for developing a space scale for measuring mass in a microgravity environment was proposed by using the inertial force properties of an object to measure its mass. The space scale detected the momentum change of the specimen and reference masses by using a load-cell sensor as the force transducer based on Newton's laws of motion. In addition, the space scale calculated the specimen mass by comparing the inertial forces of the specimen and reference masses in the same acceleration field. By using this concept, a space scale with a capacity of 3 kg based on the law of momentum conservation was implemented and demonstrated under microgravity conditions onboard International Space Station (ISS) with an accuracy of ${\pm}1g$. By the performance analysis on the space scale, it was verified that an instrument with a compact size could be implemented and be quickly measured with a reasonable accuracy under microgravity conditions.

• Journal of the Korean Society for Precision Engineering
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• v.22 no.12 s.177
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• pp.77-86
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• 2005

This paper is about the development of Automatic FPC(flexible printed circuit) punching instrument for the improvement of working condition and cost saving. FPC is used to detect the contact position of keyboard and button like a cellular phone. Depending on the quality of the printed ink and position of reference punching point to the FPC, the resistance and current are varied to the malfunctioning values. The size of reference punching point is 2mm and the above. Because the punching operation is done manually, The punching accuracy is varied with operator's condition. Recently, The punching accuracy has deteriorated severely to the 2mm punching reference hall so that assembly of the K/B has hardly done. To improve this manual punching operation to the FPC, automatic FPC punching system is introduced. Precise mechanical parts like a 5-step stepping motor and ball screw mechanism are designed and tested and low cost PC camera is used fur the sake of cost down instead of using high quality vision systems for the factory automation. Test algorithms and programs showed good results to the designed automatic punching system and led to the increasement of productivity and huge cost down to law material like FPC by avoiding bad quality.

• The KSFM Journal of Fluid Machinery
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• v.2 no.2 s.3
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• pp.19-26
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• 1999

Thermal output in a nuclear power plant is verified with calorimetric heat balance on the secondary plant. The calorimetry involves the precise measurement of the feedwater flow rate. However, the correct indication of feedwater flow rate obtained by a pressure-difference measurement across a venturi can be affected by instrument errors, fouling or a poorly developed velocity profile. This can result in an inaccurate mass flow rate and consequently an inaccurate estimate of power. The purpose of this study is to develop verification methods with accuracy better than $0.5\%$ for high precision flow measurement to be used for measuring feedwater flow rate. This chemical tracer method is a testing process that uses tracers which can be applied to quantify losses in electrical output due to the incorrect measurements of feedwater flow rate. And this system has good response to the variation of the flow rate. Accuracy of better than 0.5 percent can be expected for feedwater flow measurement, providing that the system can be stabilized during the test. This methodology is applicable to other flow systems well.