• Journal of computational fluids engineering
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• v.20 no.3
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• pp.35-40
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• 2015

Centrifugal pumps consume considerable amounts of energy in various industrial applications. Therefore, improving the efficiency of pumps machine is a crucial challenge in industrial world. This paper presents numerical investigation of flow characteristics in volutes of centrifugal pumps in order to compare the energy consumption. A wide range of volumetric flow rate has been investigated for each case. The standard k-${\varepsilon}$ is adopted as the turbulence model. The impeller rotation is simulated employing the Multi Reference Frames(MRF) method. First, two different conventional design methods, i.e., the constant angular momentum(CAM) and the constant mean velocity (CMV) are studied and compared to a baseline volute model. The CAM volute profile is a logarithmic spiral. The CMV volute profile shape is an Archimedes spiral curve. The modified volute models show lower head value than baseline volute model, but in case of efficiency graph, CAM curve has higher values than others. Finally for this part, CAM curve is selected to be used in the simulation of different cross-section shape. Two different types of cross-section are generated. One is a simple rectangular shape, and the other one is fan shape. In terms of different cross-section shape, simple rectangular geometry generated higher head and efficiency. Overall, simulation results showed that the volute designed using constant angular momentum(CAM) method has higher characteristic performances than one by CMV volute.

• Fashion & Textile Research Journal
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• v.20 no.4
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• pp.429-438
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• 2018

This study analyzed the fit-zone of the neck for females in their 60s. We considered the standard body types of females in their 60s and the four body types from the sixth Size Korea. The results of the study were as follows. We could not determine a pattern formula for the neck based on the changes in the body type of females in their 60s. However, the position of the lateral neck point generally showed a significant difference from that of females in their 20s. In the case of the shoulder angle, the point of the shoulder was angled slightly towards the back in all body types. It was also found that the curve of the neck circumference for both the collar and the bodice should have been smoother than what was shown on the 3D shape. The larger the height difference between the point of the back of the neck and the lateral neck point in the 3D shape, the smoother the design should be at the curve of the circumference at the front of the neck. A larger curvature in the front radius of the 3D shape increased the difference in the shape of the curve between the collar and the basic pattern of the bodice. Hence, a more careful design is required for these parts of the pattern. In addition, the more the front neck is bent, the smoother the circumference curve should be in the pattern design at the front of the neck and the collar.

• Journal of the Korean Society of Clothing and Textiles
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• v.28 no.11
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• pp.1426-1437
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• 2004

The study has an objective of providing the basic data for the bodice basic pattern that is highly appropriate after classifying the torso shapes of women in 60s. In order to classify the torso shape, 200 women in 60s that reside in Seoul were investigated for 52 tests. The factor analysis produced total of 6 factors. Factor 1 tended to be posture of upper part of torso and shape of shoulder. Factor 2 was an element of silhouette and Factor 3 was vertical size of lower part of torso and side silhouette. Factor 4 showed to be width and thickness of torso, Factor 5 was shape of neck, and Factor 6 appeared to be sagging of belly and buttocks. Therefore, it can be known that posture, silhouette, shape of neck and shoulder, sagging of belly and buttocks, and etc. are important factors for classification of the torso shape of women in 60s. Through a cluster analysis, each torso shape was classified into 4 types and each type showed information on size, shape, and posture clearly. Type 1 showed percentage of 24.2%, and values of height and weight showed to be average. Also, the body shape hardly had any curve with high shoulder at the Posture of upper body, and they had saggy stomach and buttocks. 43.5% of them were involved in Type 2 and they were short and overweighted. They were comparatively large in width compared to the height with no curves. Type 2 had the largest percentage and this can be said to be the special shape of women in 60s. People of Type 3 were short and overweighted just like Type 2 and all the sizes were similar to those of Type 2 or bigger. The posture is right posture and 21.7％ fall into this type and there is no body curve. This type is the shortest and most overweighted type, and it is a torso shape with right posture just like Type 4. Type 4 is a torso shape with tallest height and least weight. The percentage was the smallest(10.6％) and the width was smaller than any other type but the height was the tallest. The body curve is very clear and they have thin body but big buttocks so it can be said that the people of this type have the best silhouette. Type 2 that had the highest percentile is short and overweighted so it can be said that Type 2 is the representative torso shape of women in 60s.

• Journal of the Korean Society of Costume
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• v.30
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• pp.201-210
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• 1996

The perpose of this study is to compare and to analyze the characters of the shape of up-per arm and armscye line between young and aged women. The subjects were measured with the Mar-tin's anthropometer and with free curve ruler. 10 items in the shape of upper arm were measured and 16 items in the shape of armscye line measured indirectly based on the measured shape taken from the subjects with free curve ruler and both date were analyzed. Mean standard deviation f-test factor analysis were performed for the statistical analysis of the date. The main results were as follows: 1) The shape of the upper arm is long and narrow in youg women compared with aged. 2) The length of the axilla of the aged women were longer than that of young women. 3) There are significant differences young and aged women on the shape of armscye line. THe length of from the front point of axilla to shoulder point width and depth of the shape of the armscye line length of axilla of aged women were longer than that of young. but the length of from the back point of axilla to shoulder point of yyoung women was longer than aged. 4.) The front point of axilla was existed lower than back point of axilla in aged women while front point of axilla was existed higher than the back point in young. 5) Through the factor analysis two factors were obtained from the shape of the upper arm and five factors from the shape on armmscye line in both groups. Factor compornents in the shape of the up per arm were length width and girth of that and in the shape of the armscye line were width and length of upper and lower back and front part of the shape of the armscye line depth of the axilla. he items in the same factor were resemble each other between two groups.

• Journal of Wetlands Research
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• v.20 no.3
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• pp.243-248
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• 2018

This study was carried out to clarify changes in community structure of Quercus acutissima dominant stand on the south slope of Mt. Danseok-san with fixed twenty quadrates. Five field surveys were conducted from Aug. 1999 to May 2018. During the period, the density lessened to 0.20 in 2012 comparing with 0.33 in 1999. However recent field study in 2018 showed moderate rising to 0.24. In 1999, the DBH class distribution of all trees formed reverse J curve. However, the reverse J curve was torn down, forming bell curve. In 2018, the curve showed similar shape of reverse J shape on the group of young trees, forming bell shape on the group of mature trees. It reveals that DBH 13cm is on the threshold of trees competition trend where the downtrend in the trees are on uptrend. The most dominant Q. acutissima formed bell curve. The peak of the curve shows the shift to the right of the graph as it gets lower by year.In case of Q. mongolica, shows a change in the shape of a low bell as the distribution curve increases. The oak stand in this study is in the process of changing from the initial stage of the secondary forest succession to the intermediate stage. The most dominant tree is Q. acutissima, and the sub-dominant tree is Q. mongolica in present. Considering the age distribution of the two competing tree species, the succession of this stand is expected to transfer to the Q. mongolica-dominant community.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.10a
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• pp.1008-1012
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• 1997

This study is on a mathematical model of profile shifted involute gear, and this model is based on Camus's theory. Gear is general mechanical elements that used for power transmission between two shafts that interval is comparatively short. and it delivers bit power as accurate ratio of speed. The profile of Spur gear which is the most basic factor is divided into Trochoidal fillet curve and Involute curve. Involute curve is used a lot of a shape curve of machine parts such as a gear, a scroll compressor and a collar of centrifugal pump. However, It is poor to study the modeling of Trochoidal fillet curve and the three dimensions model shaped mathematical curve. So we draw three dimensions gear have accurate mathematical function using ADS(Automatic Drawing system), VisualLISP. To check accuracy and perfection, we make a program of checking Interference. and use for this study.

• Journal of the Korean Society of Clothing and Textiles
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• v.39 no.6
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• pp.826-837
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• 2015

This study analyzes the shapes of the adjustment of a Napoleon Collar which combines a stand collar with an upper collar. It established experimental conditions for fixing the conditions of Napoleon Collar components (lapel width, stand collar size and upper collar size) as well as varied the shape of the neckline, the length of the curve of a stand collar and the size of the drawing space at the center back. It produced 22 test clothes of muslin, which were dressed on dress form No. 8. The results indicate that: 1. Neckline shape determines the amount of stand and fall. Less curved neckline stands higher against the neck and a more curved neckline is laid lower onto the body. 2. A shorter curve length of a stand collar allows a longer roll line to fall farther away from the neck with more space between the neck and collar. However, the longer the depth of curve of a stand collar creates a shorter roll line that stands high against neck and closer to neck without any space between the neck and collar with a collar line matching the neck of the dress form. 3. The smaller the drawing space at the center back creates a shorter the style line of the upper collar. However, a narrower back width of the collar creates a bigger drawing space at the center back with a longer the style line and a more naturally placed back width of the collar. 4. A Napoleon Collar creates a longer depth of curve for a stand collar and a smaller drawing space at the center back that is tightly and stably stuck to the neck.

• Journal of Astronomy and Space Sciences
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• v.13 no.1
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• pp.19-31
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• 1996

We have analyzed collected photoelectric light curves for light variations of SW Lac. The method of Fourier analysis was adopted to quantify the light variation from season to season. We found the linear relation between the Fourier coefficient, B1 and the magnitude difference between two maxima. The total light of the system has been decreased as much as 0m.04 during approxiamately 20 years time interval. Photoelectric parameters including spot parameters for all light curves were obtained by the method of the Wilson and Devinney differential correction in order to secure the variations of parameters from season to season. SW Lac, not like RS CVn type stars, required to adjust all parameters as well as spot parameters for a reasonable fit to the observations of each epoch. A surface temperature of cooler star is one of the most sensitive parameters to affect a shape of light curve of SW Lac. We conclude that the shape of light curve of SW Lac varies even during one season as well as season to season. The light curve is mainly caused by inhomogeneous surface temperature due to strong chromospheric activity of the system.

• 제어로봇시스템학회:학술대회논문집
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• 1996.10a
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• pp.430-433
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• 1996

The shape of an object plays a very important role in pattern analysis and classification. Roughly, the researches on this topic can be classified into three fields, i.e. (i) edge detection, (ii) dominant points extraction, and (iii) shape recognition and classification. Many works have been done in these three fields. However, it is very seldom to see the research that discusses the connection relationship of objects. This problem is very important in robot assembly systems. Therefore, here we focus on this problem and discuss how to recover the connection relationship of planar objects. Our method is based on the partial curve identification algorithm. The experiment results show the efficiency and validity of this method.

• Proceedings of the KIEE Conference
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• 1991.11a
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• pp.67-70
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• 1991

When analyzing field or optimizing the shape of electrode in three dimensional space by using the surface charge method, we need to divide finely the surface of electrode into surface element like triangle or rectangle. In this case, there exist any variables in field analysis or field optimization. In particular, smoothness on the surface of optimized shape is not good. Recently, A paper is published where introducing NURB curve to field analysis and field optimization about two dimensional space model and axial symmetric three dimensional space model results in reduced variables, enhenced accuracy and improved smoothness. NURB curve has some useful properties like continuity, controllability and locality. Therefore in this paper, in order to improve the demerits of the established optimization method for three dimensional space models, the NURB surface that has same properties in common with NURB curve is used to analyze and optimize simple model.