• Journal of Korean Society of Forest Science
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• v.89 no.5
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• pp.666-676
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• 2000

For the study of morphological variation of Q. variabilis natural population in Korea, 19 populations were selected through the country in considering latitude, longitude, and geographical characters. Thirty trees were randomly selected from each population and 60 mature leaves were sampled from each tree. Four characters (leaf blade length, maximum blade width, petiole length, and vein number) were measured, and their ratios (the ratio of blade length to maximum blade width, the ratio of blade length to petiole length, the ratio of petiole length to vein number, upper 1/3 blade width to maximum blade width, and upper 1/3 blade width to lower 1/3 blade width) were calculated. 1. Analysis of variance for all leaf characters were significantly different among populations and among individuals within population. Contributions of variance among individuals within population in all the characters were higher than those among populations. Therefore, selection of plus trees may be preferable to desirable populations for breeding program of Q. variabilis. 2. Among principal component analysis for leaf characters, primary 2 principal components appeared to be major variables for leaf form of Q. variabilis because of the loading contribution of 80.5%. The first contribution component was petiole length/vein number and petiole length ; the second one was upper 1/3 blade width/maximum blade width, upper blade width/lower 1/3 blade width and vein number, respectively. 3. Latitude was positively correlated with blade length/maximum blade width and blade length/petiole length, but negatively correlated with petiole length/vein number, upper 1/3 blade width/maximum blade width, upper 1/3 blade width/lower 1/3 blade width, petiole length, and vein number. But, for longitude and altitude the former two traits and the later five traits exhibited the negative and positive correlation, respectively. 4. Cluster analysis using complete linkage method for leaf characters showed two groups to Euclidean distance 1.6. They were group I of population 1. 4, 5, and 13 and group II of population 2, 3, 6, 7, 8, 9, 10, 11, 12, 14, 15, 16, 17, 18, and 19. However, group II was divided again to Euclidean distance 1.3, that is a group including population 3, 7, 10, 14, 15, and 17(group II-1) and the other group comprising population 2, 6, 8, 9, 11, 12, 16, 18, and 19(group II-2). This cluster could be mainly observed due to difference among population in aspect (group I : NE, group II-1 : SE, and group II-2 : SW).

• 제어로봇시스템학회:학술대회논문집
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• 1990.10a
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• pp.799-804
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• 1990

In the blade grinding process, Blade image is captured. It is captured in the environment with vibration, using monochrome CCD camera with high speed electronic shutter. The image is preprocessed using LoG filter and zero crossing. We used Hough transformation to detect straight lines from the preprocessed image. From the equations of detected lines, we calculated width between lines caused by grinders. This paper proposes automatic measurement of blade width to automate the process control of blade grinding line.

• Journal of Korean Society of Forest Science
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• v.71 no.1
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• pp.82-89
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• 1985

Morphological characteristics of leaves of 10 natural populations of Quercus mongolica and 9 natural populations of Q. serrata were investigated to study inter-population and intra-population variability as well as interspecies variability. Five leaf form indices, blade length/max. blade width, blade length/petiole length, blade length/vein number, upper 1/3 blade width/max.blade width, upper 1/3 blade width/lower 1/3 blade width, as well as petiole length and vein number were included in the present study of Leaf variabilities of the Quercus population. All of the investigated leaf variabilities except for the case of blade length/petiole length, in Q. serrata indicated highly significant differences among the populations and among the individual trees within population. Both of Q. mongolica and Q. serrata represented different leaf forms between southern populations and northern populations in the indices of blade length/max. blade width, blade length/petiole length and blade length/vein number, and so the leaf forms of northern populations were more similar to the unique characters of Q. mongolica and those of southern populations were more similar to the unique characters of Q. serrata. The variability among individual trees within population was more notable in blade length/petiole length, and petiole length than in other leaf form indices, and also it was more obvious for Mt. Kyeryrong population located in middle part of the country than for other population.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.21 no.2
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• pp.7-14
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• 2013

In this paper, the optimal design of composite rotor blade cross-section is performed using a genetic algorithm. Skin thickness, torsion box thickness and skin lay-up angle are adopted as discrete design variables. The position and width of a torsion box are considered as continuous variables. An object function of optimal design is to minimize the mass of a rotor blade, and constraints are failure index, center mass, natural frequency and blade minimum mass per unit length. Finally, design variables such as the thickness and lay-up angles of a skin, and the thickness, position and width of a torsion box are determined by using an in-house program developed for the optimal design of rotor blade cross-section.

• Journal of Aerospace System Engineering
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• v.8 no.1
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• pp.12-17
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• 2014

In this paper, optimal design of composite rotor blade cross-section to consider manufacturability was performed. Skin thickness, torsion box thickness and skin lay-up angle were adopted as discrete design variables and The position and width of a torsion box were considered as continuous variables. An object function of optimal design is to minimize the mass of a rotor blade, and various constraints such as failure index, center mass, shear center, natural frequency and blade minimum mass per unit length were adopted. Finally, design variables such as the thickness and lay-up angles of a skin, and the thickness, position and width of a torsion box were determined by using an in-house program developed for the optimal design of rotor blade cross-section.

• Journal of Korean Society of Forest Science
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• v.97 no.4
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• pp.431-436
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• 2008

7 populations of rare endemic Berchemia berchemiaefolia were analysed using multivariate analysis for 9 characteristics of leaf morphology. The aim of this study was to examine geographic variation to support a genetic resource conservation plan of B. berchemiaefolia in Korea. In the morphological characters, nine characters of leaf were 10.25 cm (blade length), 4.10 cm (maximum width), 2.52 (blade length/maximum width), 3.22 cm (upper 1/3 width), 3.42 cm (lower 1/3 width), 0.95 (upper 1/3 width/lower 1/3 width), 1.24 cm (petiole length), 8.91 (blade length/petiole length), 8.16ea (vein number), respectively. Nested anova showed that were statistically significant differences among populations as well as among individuals within populations in all 9 quantitative characters. In 7 of 9 characters, variance components among individuals within populations were higher than those among populations. Cluster analysis using complete linkage method showed two groups (Chungbuk and Gyeongbuk districts) to Euclidean distance 1.2. Among principal components, primary 3 principal components appeared to be major variables because of the loading contribution of 87.3%. The first contribution was blade length, blade length/maximum width and blade length/petiole length; the second one was maximum width, upper 1/3 width and lower 1/3 width; the third one was petiole length, respectively.

• 유체기계공업학회:학술대회논문집
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• 1998.12a
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• pp.135-141
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• 1998

Some sized centrifugal compressor were designed and their performance measured to investigate the effects of exit blade thickness, width and back swept angle. The impeller of larger blade thickness shows low pressure ratio compared with that of smaller one. Backswept angle have also large effect on the efficiency. Measured values of slip factor are quite different from the estimated values of Wiesner-Busemann model and increase with the flow rate.

• The KSFM Journal of Fluid Machinery
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• v.2 no.1 s.2
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• pp.15-21
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• 1999

Some sized centrifugal compressors were designed and their performance measured to investigate the effects of exit blade thickness, width and back swept angle. The impeller of larger blade thickness shows low pressure ratio compared with that of smaller ones. Backswept angle also have a large effect on the efficiency. Measured values of slip factor are quite different from the estimated values of the Wiesner-Busemann model and an increase in the flow late.

• Advances in aircraft and spacecraft science
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• v.11 no.2
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• pp.153-175
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• 2024

In jet engines, turbine blade cooling has an extremely important role. The pin-fin array, which is situated close to the trailing edge of the blade, aids in internal cooling of the gas turbine blades and preserves the structural integrity of the blade. Previous studies often focused on pin-fin configurations, but the current research focuses on improving the geometry at the endwalls to reduce wake vortices behind the pin-fins and enhance heat transfer at the endwalls location. Using the k-ω turbulence model, a numerical study was conducted on a ribbed shape situated on the walls between pin-fin arrays, spanning a Reynolds number range of 7400 to 36000, in order to determine the heat transport characteristics. The heat transfer efficiency coefficient and Nusselt number increase dramatically with the revised wall configuration, according to the numerical data. The channel's heat transfer efficiency is increased by enlarging the heat transfer areas near the pin-fins and by the interaction of the flow with the endwalls. The addition of ribs causes the Nusselt number of the new model to climb from 78% to 96% at the previously given Reynolds numbers, and the heat transfer efficiency index to rise from 60% to 73%. The height (Hr), position (Lr), forward width (Wf), and backward width (Wb) of the ribs are among the geometric elements that were looked at in order to determine how they affected the performance of heat transmission. In comparison to the reference design, the parametric study results demonstrate that the best forward width (Wf/R=18.75%) and backward width (Wb/R=31.25%) increase the heat transfer efficiency index by 0.4% and 1.3%, respectively.

• Journal of Welding and Joining
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• v.19 no.3
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• pp.298-304
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• 2001

Turbine blade is subject to force of three types ; the torsional force by torsional mount, the centrifugal force by the rotation of rotor and the cyclic bending force by steam pressure. The cyclic bending force was a main factor on fatigue strength. SEM fractography in root of turbine blade showed micro-clack width was not dependent on stress intensity factor range. Especially, fatigue did not exist on SEM photograph in root of turbine blade. To clear out the fracture mechanism of turbine blade, nanofractography was needed on 3-dimensional crack initiation and crack growth with high magnification. Fatigue striation partially existed on AFM photograph in root of turbine blade. Therefore, to find a fracture mechanism of the torsion-mounted blade in nuclear power plant, the relation between stress intensity factor range and surface roughness measured by AFM was estimated, and then the load amplitude ΔP applied to turbine blade was predicted exactly by root mean square roughness.