• Journal of the Ergonomics Society of Korea
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• v.18 no.3
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• pp.179-186
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• 1999

This article aims to provide information necessary for the measurement and analysis of human vibration, especially hand-arm vibration. The major health problems associated with the use of powered hand tools are the signs and symptoms of peripheral vascular and peripheral neural disorders of the fingers and hands. To prevent these problems, it is the first and the most important to measure the amount of the vibration transmitted to the upper extremities, and analyze its characteristics against the exposure limits such as ISO standards. In our country, however, very few studies have been done on the hand-arm vibration. One of the possible reasons might be lack of knowledge for the measurement and analysis schemes. The information introduced in this article would hopefully be of help for the upcoming studies.

• Journal of the Korean Society of Mechanical Technology
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• v.13 no.2
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• pp.71-78
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• 2011

A kart is a vehicle without the suspension system and the differential gear. The kart frame as an elastic body plays the role of a spring. By the cornering of a kart, rolling, pitching and twisting motions are induced in the kart frame. Also the slip or noncontact of the wheel and a permanent deformation of the kart frame can be induced. In order to examine closely this phenomenon, measurement on height-displacements with various sensors and tracking system and analysis on the kart frame twisting characteristics with the rolling and pitching angle are needed. According to the measurement result, while driving in a curve at high speed the kart frame is quite twisted. Analysis on the measurement results shows that a kart used primarily in high speed requires a frame with low torsional stiffness and a frame material with high tensile strength and large elongation.

• Special Issue of the Society of Naval Architects of Korea
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• 2011.09a
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• pp.1-4
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• 2011

The full spade rudder for the high speed has advantage to prevent gap cavitation of the rudder. DSME has developed the full spade rudder and GL has carried out CFD analysis and FE analysis to confirm strength and fatigue for DSME and Owner. Necessarily, it needs to compare rudder torque & rudder force between CFD, FE analysis and full scale measurement. This report introduces the measurement method and application of strain gauge for measuring the rudder torque and rudder force for the 8,400 TEU container ship.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.11b
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• pp.1040-1043
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• 2001

This paper describes the principle behind Crank Angle Analysis, as implemented by Bruel ＆ Kjaer in the Non-Stationary Spatial Transformation of Sound Fields (NS-STSF) system. The NS-STSF system combines a Time Domain Holography measurement on for example an engine with two simultaneously recorded Tacho signals. The Tacho signals provide the crankshaft angle and the RPM at the instant of each instantaneous output (snap-shot) from Time Domain Holography. As a result, the system allows precise analysis of the temporal and spatial relation between the acoustical emission (or the vibration pattern) and the mechanical events during an engine cycle. Some results from a measurement on a DaimlerChrysler engine are presented.

• Journal of the Optical Society of Korea
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• v.9 no.2
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• pp.54-58
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• 2005

A novel mode analysis method and differential mode delay measurement technique for a multimode optical fiber based on optical frequency domain reflectometry has been proposed for the first time. We have used a conventional OFDR with a tunable external cavity laser and a Michelson interferometer. A few-mode optical multimode fiber was prepared to test our proposed measurement technique. The differential mode delay (DMD) of the sample fiber was measured to be 16.58 ps/m with a resolution of 1.5 ps/m. We have also compared the OFDR measurement results with those obtained using a traditional time-domain measurement method.

• Coupled systems mechanics
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• v.11 no.1
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• pp.33-41
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• 2022

Quite often we have a lot of measurement data and would like to find some relation between them. One common task is to see whether some measured data or a curve of known shape fit into the cumulative measured data. The problem can be visualized since data could generally be presented as curves or planes in Cartesian coordinates where each curve could be represented as a vector. In most cases we have measured the cumulative 'curve', we know shapes of other 'curves' and would like to determine unknown coefficients that multiply the known shapes in order to match the measured cumulative 'curve'. This problem could be presented in more complex variants, e.g., a constant could be added, some missing (unknown) data vector could be added to the measured summary vector, and instead of constant factors we could have polynomials, etc. All of them could be solved with slightly extended version of the procedure presented in the sequel. Solution procedure could be devised by reformulating the problem as a measurement problem and applying the generalized inverse of the measurement matrix. Measurement problem often has some errors involved in the measurement data but the least squares method that is comprised in the formulation quite successfully addresses the problem. Numerical examples illustrate the solution procedure.

• Advances in biomechanics and applications
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• v.1 no.4
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• pp.269-277
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• 2014

In skin-marker based motion analysis, knee translation measurement is highly dependent on a pre-selected reference point (functional center) on each segment determined by the location of anatomical landmarks. However, the placement of skin markers on palpable anatomical landmarks (i.e., femoral epicondyles) has limited reproducibility. Thus, it produces large variances in knee translation measurement among different subjects, as well as across studies. In order improve the repeatability of knee translation measurement, in this study an optimization method was introduced, by which the femoral functional center was numerically determined. At that point the knee anteroposterior translation during the stance phase of walking was minimized. This new method was tested on 30 healthy subjects during walking in gait lab with motion capture system. Using this new method, the impact of skin marker position (at anatomical landmarks) on the knee translation measurement has been minimized. In addition, the ranges of anteroposterior knee translations during stance phase were significantly (p<0.001) smaller than those measured by conventional method which relies on a pre-selected functional center ($11.1{\pm}3.5mm$ vs. $19.9{\pm}5.5mm$). The results of anteroposterior translation using this new method were very close to a previously reported knee translation (12.4 mm) from dual fluoroscopic imaging technique. Moreover, this new method increased the reproducibility of knee translation measurement by 50%.

• Fibers and Polymers
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• v.6 no.1
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• pp.79-81
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• 2005

Fuzz on the fabrics, which is the fibers protruded from the fabric surface, is very important in view of appearance quality, since it causes unpleasant appearance on the fabrics and also leads to pilling which makes fabric appearance and soft­ness worse. However, fuzz on fabric surface is measured mostly by subjective methods (human vision) rather than objective methods. Thus, in this study, objective method using image analysis techniques has been developed for the measurement of fuzz on fabric surface. Fuzz on the fabric has also been ranked and rated by experts in order to see the reliability of the results obtained from the fuzz measurement. It was observed that correlation coefficient (r) between rating value and objective mea­surement value was 0.9 and this correlation coefficient value confirmed the reliability of this method.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2022.11a
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• pp.323-324
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• 2022

This paper explains the comparison results of surface current measurement using X-band Radar image through analysis. Measurements were carried out from February 2022 using the X-band Radar for marin ships installed at Sokcho Beach. Based on the Korea Hydrographic and Oceanographic Agency ocean observation buoys, the accuracy of surface current(current speed) measurement was verified through comparison and analysis of measurement data.

• Journal of Fashion Business
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• v.11 no.4
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• pp.135-151
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• 2007

This study is human body measurement of 200 adult males in their 20s by both direct and indirect methods in order to reveal the representative male upper body types. Composition factors of body types were classified while the combination of direct-indirect measurement values was chosen. The following are the findings: 1) The analysis of direct-indirect measurement statistics showed the following results: 173.80cm (height), 69.87kg (weight), 95.58cm (chest girth), $24.67^{\circ}$ (right shoulder angle), and $9.34^{\circ}$ (shoulder width angle). 2) The factor analysis of the body types by direct measurement produced 5 factors: 1 (front length of upper body), 2 (front length of upper body), 3 (back length of upper body), 4 (circumference of upper body), and 5 (shoulders length). These factors accounted for 90.08%. Also, the cluster analysis of factor scores led to 3 types: 1 (33%, short, comparatively wide shoulders and full in the hips), 2 (25.1%, well-developed upper body in tall, inversed triangle), 3 (41%, average height, short upper body). 3) The body-type factor analysis by indirect measurement resulted in 6 factors with the explanation of 83.24%: 1 (rear upper bady thickness), 2 (front upper body width), 3 (front chest thickness), 4 (left-right shoulder angle), 5 (front width of protrusion distance in chest and shoulders), and 6 (neck's front-rear side angle).In addition, the cluster analysis of factor scores brought about 4 types: 1 (15%, well-developed front chest, beardless waist), 2 (23.5%, flat chest, with shoulder, drooping shoulders, strait neck), 3 (39%, with shoulder, curved back), and 4 (22.5%, narrow and thin, curved waist). 4) Among the 118 subjects (75%), 58 subjects commonly appearing in indirect measurement values group and direct measurement values group were chosen the representative body type group according to asterisk indexes. They had the highest frequency in direct type 3 and indirect type 3, whose combination represented the physical characteristics of the representative body types.