• 패션비즈니스
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• 제19권6호
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• pp.28-41
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• 2015

Properties of textile fabrics influence the appearance, aesthetics, and performance of garment. Drape and related properties of fabrics affect profoundly the static and dynamic appearance during wearer's movement. The three dimensional shape of the folded structure often deforms with time or with subtle vibration around the fabric specimen during the drape measurement. Due to the uneven and complex nature of fabrics, the overall shape of the fabric specimen on the drape tester often becomes unstable. There is a need to understand the fundamental mechanisms of how draping may generate pleasing forms. Two drape test methods, conventional Cusick drape test, and in-built drape tester, based on a depth camera, are compared. Fabric specimens including cotton, linen, silk, wool, polyester, and rayon are investigated for the fabric drape and other physical/mechanical parameters. Drape coefficient values of fabric specimens are compared based on the final drape images, together with the intermediate 3D drape images of the specimens during elevation process of the drape tester equipped with a stepper motor system. The correlation coefficient between the data based on the two methods is reasonably high. Another advantage from the depth camera system is that it allows further analysis of three-dimensional information regarding the fabric drape shape, including the shape of nodes or crest and trough.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2000년도 사면안정 학술발표회
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• pp.213-220
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• 2000

Numerical modeling of cut slope has some limits in simulating the real slopes. In the case of 2D analysis of slope stability, it is assumed that slope is simply straight even when it is concave or convex in plan view. In this study, 3D analysis in curved shape slopes has been conducted for the comparison with 2D analysis in terms of failure mode and factor of safety. For this, 3D analysis by FLAC3D was compared with 2D analysis in plane strain condition and axi-symmetric model condition by FLAC. It was also observed how safety factors of slopes were affected by the variation of the tensile strength and cohesion, which are important variables to decide whether the slope fails or not. 2D analysis of concave slopes under plane strain condition showed much smaller safety factors by 16-40 % errors depending on the radius of curvature of slopes, compared to the more realistic values from 3D analysis. In case of convex slopes, the lower values by 7-10 % has been reported. 2D analysis of axi-symmetric model showed also smaller safety factors by 6-10 % and by 2-4 %, in case of concave and convex slopes, respectively. Such results are expected to contribute to the better understanding of failure process and could be applied for improved design of slopes.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회A
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• pp.155-160
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• 2008

Using a three-dimensional (3-D) FE analyses, this paper provides the shape optimization of the standard test specimen for the torsion test, as well as a method for analyzing effects of misalignment under the angular and concentric misalignment. For verification, FE analysis is performed, which is designed for the perfectly full-model. To optimize the design shape of the torsion-controlled fatigue test specimen, we performed sensitivity analysis using shape parameters. Additionally, two kinds of misalignment (angular misalignment and concentric misalignment) are applied to the circular and tubular specimens to show effects of misalignments in the FE analysis. The present results will provide valuable information for designing shafts for every kind of mechanical system under torsional force.

• 한국의류학회지
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• 제28권1호
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• pp.182-188
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• 2004

The purpose of the study was to provide scientific and accurate data of head shape for men. This study was carried out on 214 men and Factor analysis, Cluster analysis, Duncan analysis with 15 variables were performed using the data. A 3D scanner was used for visual results of head shape. The results were as follows. First, through factor analysis of the variables, three factors were extracted upon factor scores. The first factor described thickness part, and second factor described width parts and the third factor described vertical length parts. Four clusters represented characteristics of men's head types. Type 1 had a larger head thickness, type 2 had a smaller thickness and smaller width. type 4 had a generally larger head. In the distribution of the four clusters, type 1 was distributed 34%. Type 4 was distributed 23%. According to the results, type 1 of the more thick and narrow head was dominant among head types of men.

• 한국산업융합학회 논문집
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• 제25권5호
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• pp.899-908
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• 2022

In this study, a study was conducted to localize a large aluminum turbo fan used for tank powerpack. The turbo fan was scanned with a 3D scanner and then 3D modeling was performed. Computational fluid dynamics (CFD) were performed from the performance conditions of the fan, and structural analysis was performed using the pressure data obtained from CFD. The fan was reduced to 1/5 size by applying the geometric similarity. A 1/5 size fan has a honeycomb structure inserted into the front shroud and back shroud to reduce the weight by 5.3%. A 1/5 size fan was printed using a PBF 3D printer, and a 1/5 size fan with honeycombs was also printed. The pressure drop of 8.67 kPa and the required power of 138.19 kW, which satisfies the performance conditions of the fan, were confirmed from the results of CFD. The values of the maximum deformation amount of 0.000788 mm and the maximum effective stress of 0.241 MPa were confirmed from the structural analysis results. The fan printed by the PBF 3D printer had the same shape as the modeling, and the shape was perfect. There are no defects anywhere in appearance. However, the condition of the outer surface of the fan's back shroud is rough compared to other locations. The fan in which the honeycomb was inserted was also perfectly output, and the shape of the honeycomb was the same as the modeling.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1997년도 하계학술대회 논문집 A
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• pp.171-173
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• 1997

This paper presents analysis of the radial force density in brushless DC motor of which distribution is not uniform in the axial direction. The analysis considering 3D shape of teeth and overhang is not only important but essential to calculate the radial force density that acts on the teeth of stator, because it is frequent source of vibration and changes at the end of teeth. For the analysis, a new 3D equivalent magnetic circuit network method taking into account movement of the rotor without remesh is proposed. The radial force density is calculated by Maxwell stress tensor and analyzed by discrete Fourier transform.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회A
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• pp.1570-1575
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• 2007

The cold-forging process analysed in this paper deals with the cam bolt of a nonaxisymmetric shape which mainly is used as a part in the steering system of a vehicle for the purpose of adjusting shock absorb. So both strength and endurance are very important for the cam bolt. In this study, cam bolt forging process is composed of four stage processes. For three forging stages, shape of workpiece will be eccentrical. And then bolt head and washer of eccentrical shape is created in last stage. 3D finite element analysis repeatedly has been performed with changing dimension of die to obtain adequate former multi forging process and die shape. Simulation results reviewed have influence on deciding design of die and forging process. As a result, Simulation results have provided a direction to improve the process.

• 한국분무공학회지
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• 제23권4호
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• pp.192-204
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• 2018

In this study, a 3D CFD analysis method for the combustion process was established for a low calorific value syngas-diesel dual-fuel engine operating under very lean fuel-air mixture condition. Also, the accuracy of computational analysis was evaluated by comparing the experimental results with the computed ones. To simulate the combustion for the dual-fuel engine, a new dual-fuel chemical kinetics set was used that was constituted by merging two verified chemical kinetic sets: n-heptane (173 species) for diesel and Gri-mech 3.0 (53 species) for syngas. For dual-fuel mode operations, the early stage of combustion was dominated by the fuel burning inside or near the spray plume. After which, the flame propagated into the syngas in the piston bowl and then proceeded toward the syngas in the squish zone. With the baseline injection system and piston shape, a significant amount of unburned syngas was discharged. To solve this problem, effects of the injection parameters and piston shape on combustion characteristics were analyzed by calculation. The change in injection variables toward increasing the spray plume volume or the penetration length were effective to cause fast burning in the vicinity of TDC by widening the spatial distribution of diesel acting as a seed of auto-ignition. As a result, the unburned syngas fraction was reduced. Changing the piston shape with the shallow depth of the piston bowl and 20% squish area ratio had a significant effect on the combustion pattern and lessened the unburned syngas fraction by half.

• 패션비즈니스
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• 제17권6호
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• pp.141-157
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• 2013

In this study, we analyzed the figure type and lower-body size of Shanghai and Hong Kong adult women in their early twenties using the data obtained from 3D whole body scanners. We also provided concrete information related to women's lower bodies, in terms of crotch width, crotch length, inseam, outseam, slope of waist, etc., among women in Shanghai and Hong Kong. The result may be useful to the Chinese apparel industry when designing trouser pants for adult women. According to the results of the factor analysis for categorizing the body shape of the lower half, 5 factors were obtained: obesity of the lower half factor, height of the lower half factor, length from waist to the crotch factor, factor related to legs, and shape of the abdomen factor. After performing a cluster analysis according to the factor analysis, three clusters were set: Cluster 1 was represented as the lower half growth type, which has a high value in height of the lower half factor and grows in the abdomen part. Cluster 2 was represented as thin legs type, which has a low value in most part compared to the length of leg bones and factors about legs that have high value. Cluster 3 was represented as the obesity type having a high value in the obesity of the lower half factor. Overall, thin legs type achieved a high rate in Shanghai adult women and obesity type received a high rate in adult women living in Hong Kong.

• 대한기계학회논문집A
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• 제27권1호
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• pp.26-33
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• 2003

Based on detailed FE limit analyses, the present paper provides tractable approximations fer plastic limit pressure solutions fur axially through-wall-cracked pipe; axially (inner) surface-cracked pipe; circumferentially through-wall-cracked pipe; and circumferentially (inner) surface-cracked pipe. In particular, for surface crack problems, the effect of the crack shape, the semi-elliptical shape or the rectangular shape, on the limit pressure is quantified. Comparisons with existing analytical and empirical solutions show a large discrepancy in circumferential short through-wall cracks and in surface cracks (both axial and circumferential). Being based on detailed 3-D FE limit analysis, the present solutions are believed to be the most accurate, and thus to be valuable information not only for plastic collapse analysis of pressurised piping but also for estimating non-linear fracture mechanics parameters based on the reference stress approach.