• Journal of the Korean Magnetics Society
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• v.25 no.2
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• pp.52-57
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• 2015

The focal spot of electron beam depending on the anode angle in the structure and major parts of the X-ray tube was investigated by the OPERA-3D/SCALAR simulation program. The simulation worked on four spaces with with two spaces, including anode and cathode of X-ray tube, by applying the finite element method analysis. The analytical model and dimension for the emission orbit of thermal electrons made from one filament of the focused X-ray cathode is affected to the penumbra of detector for the X-ray depending on any real focal spot size. The model shape of focusing cap and focusing tube with an anode target angle and a cathode filament is analyzed by the current density distribution of thermal electrons. The focusing width of thermal electrons for the X-ray tube depended on the anode angle (${\theta}$). The focusing value of electron beams at a region of anode angle having $10^{\circ}{\sim}17^{\circ}$ maintained to below value of $70{\mu}m$. The minimum focal size of the electron beam was $40{\mu}m$ at an anode angle of $15^{\circ}$. The focused X-ray tube of many variables depended on the thermionic emission of hot electrons from the target trajectory. The focusing tube will contribute to the real design of X-ray for the development of future diagnosis medical device.

• Proceedings of the KIEE Conference
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• 1999.11b
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• pp.21-23
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• 1999

In this paper, the analysis of the electric field in the chamber of high voltage $SF_6$ GCB(Gas Circuit Breaker) is presented by using C-1 FEM. For this purpose, pre-processing program and post-processing program were developed for axisymmetirc 3 dimensional analysis and the electric field in cylindric chamber was analyzed. Important problem is that electric analysis must be considered coronal due to break-down of $SF_6$ when it is cutted off. To solve this problem, a procedure is needed to verify that the solution of Poisson's equation for scalar potential satisfy charge continuos condition because of using first order element os not satisfy the electric continuous condition, C-1 FEM is introduce to obtain electirc potential and electric field at the same time. Analysis of the distribution of electric field on model was done. It is confirmed that the developed program in this paper applicable to design and to analyze of characteristics in total program as electric characteristics analysis routine.

• The Korean Journal of Ecology
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• v.9 no.3
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• pp.135-147
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• 1986

The simplification and the searching trends of complex data which assumed relationship between predictor variables and object variables are one of primary objective of ecological research. This study was aimed to apply cononical analysis consisting of canonical correlation analysis and canonical variate analysis related to lichen vegetation and several environmental variables which are elevation, height on grond, exposure side and cover values. Data collected from the Duckyoo National Park in August 1985. Lichen species was ranked by eqivocation information theory with cover values. Canonical correlation analysis was applied to one data set both set both environmental variables and lichem family. In order to make two sets of data matrix the scale of position vector ordination was calculated from the vector scalar product for lichen species. Canonical variate analysis was applied to rearranged data which was made by interval class code for environmental variables. The sharpness values was calculated in frequency of cotingency tables and the dispersion profiles of each species in classes of environmental variables was designed to extract component values based on the decomposition of expected frequencies in contingency table. The results of canonical correlation analysis revealed canonical first correlation value 0.815(89%), and second correlation value 0.083(11%). Significance test showed that the hypothesis of joint mutuallity of canonical correlation is accepted (P>0.05). The relation between canonical score of vegetation variables and that of environmental variable indicated linear tendency.

• Journal of Photoscience
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• v.11 no.3
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• pp.89-94
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• 2004

Motile cyanobacterium Synechocystis sp. PCC 6803 cells show photomovement with respect to the light stimulus. Under lateral irradiation, Synechocystis displays a phototactic gliding movement toward the light source by a twodimensional random biased walk. Under vertical irradiation, Synechocystis decreased the frequency of mean vectorial gliding speed dependent on the applied fluence rate, whereas the deviation distribution width of the speed increased. This strongly suggests the involvement of photokinesis. Evidence for the cyanobacterial photokinesis was discussed in the previous report (Choi et al., 1999. Photochem. Photobiol. 70, 95-102) demonstrating that the gross scalar speed of vertically irradiating cells increased by about 50% compared with that of dark-adapted cells. In the visible wavelength range, Synechocystis cells showed a maximal photokinetic activity at 420 nm and a second maximal activity at 680 nm. The threshold action spectrum for the photokinesis resembles the absorption spectrum of chlorophyll with major differences in the phototaxis action spectrum at 560 nm and 660 nm. We postulate that the cyanobacterial photokinesis is powered by the energy-generating chlorophyll pigments.

• Steel and Composite Structures
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• v.44 no.1
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• pp.65-79
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• 2022

The main goal of this paper is to study the vibration of damaged core laminated annular plates with FG face sheets based on a three-dimensional theory of elasticity. The structures are made of a damaged isotropic core and two external face sheets. These skins are strengthened at the nanoscale level by randomly oriented Carbon nanotubes (CNTs) and are reinforced at the microscale stage by oriented straight fibers. These reinforcing phases are included in a polymer matrix and a three-phase approach based on the Eshelby-Mori-Tanaka scheme and on the Halpin-Tsai approach, which is developed to compute the overall mechanical properties of the composite material. In this study the effect of microcracks on the vibrational characteristic of the sandwich plate is considered. In particular, the structures are made by an isotropic core that undergoes a progressive uniform damage, which is modeled as a decay of the mechanical properties expressed in terms of engineering constants. These defects are uniformly distributed and affect the central layer of the plates independently from the direction, this phenomenon is known as "isotropic damage" and it is fully described by a scalar parameter. Three complicated equations of motion for the sectorial plates under consideration are semi-analytically solved by using 2-D differential quadrature method. Using the 2-D differential quadrature method in the r- and z-directions, allows one to deal with sandwich annular plate with arbitrary thickness distribution of material properties and also to implement the effects of different boundary conditions of the structure efficiently and in an exact manner. The fast rate of convergence and accuracy of the method are investigated through the different solved examples. The sandwich annular plate is assumed to have any arbitrary boundary conditions at the circular edges including simply supported, clamped and, free. Several parametric analyses are carried out to investigate the mechanical behavior of these multi-layered structures depending on the damage features, through-the-thickness distribution, and boundary conditions.

• Journal of The Korean Astronomical Society
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• v.24 no.1
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• pp.71-94
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• 1991

With the 14 m radio telescope at DRAO and the 4 m at Nagoya University, we have made detailed maps of $^{12}CO$ and $^{13}CO$ emissions from two Barnard objects B133 and B134 in the $J=1{\rightarrow}O$ rotational transition lines. Usual LTE analyses of the CO observations led us to determine the distribution of column densities over an entire area encompassing both globules. Total gas masses estimated from the column density map are $90\;M_{\odot}$ and $20\;M_{\odot}$ for B133 and B134, respectively. The radial velocity of B133 is red shifted with respect to B134 by $0.8\;km\;s^{-1}$, which is too lagre to bind the two clouds as a binary system. We have shown that the usual stability analysis based on the simplified version of virial theorem with the second time-derivative of the moment of inertia term $\ddot{I}$ being ignored could mislead us in determining whether a given cloud eventually collapses or not. The lull version of the scalar virial theorem with the $\ddot{I}$ term is shown to be useful in following up the time-dependent variations of the cloud size R and its streaming velocity $\dot{R}$ as functions of time. Results of our stability analysis suggest that B133 will eventually collapse in $(2{\sim}4){\times}10^6$ years.

• Journal of KIISE:Software and Applications
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• v.31 no.2
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• pp.189-202
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• 2004

In this paper, we propose a new salient region detection method in an image. The algorithm is based on the characteristics of human's bottom-up visual attention. Several features known to influence human visual attention like color, intensity and etc. are extracted from the each regions of an image. These features are then converted to importance values for each region using its local competition function and are combined to produce a saliency map, which represents the saliency at every location in the image by a scalar quantity, and guides the selection of attended locations, based on the spatial distribution of saliency region of the image in relation to its Perceptual importance. Results shown indicate that the calculated Saliency Maps correlate well with human perception of visually important regions.

• Korean Journal of Agricultural and Forest Meteorology
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• v.17 no.3
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• pp.227-235
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• 2015

Using eddy covariance method, net ecosystem exchange (NEE) of $CO_2$ ($F_{CO_2}$), $H_2O$ (LE), and sensible heat (H) can be approximated as the sum of eddy flux ($F_c$) and storage flux term ($F_s$). Depending on strength and distribution of sink/source of scalars and magnitude of vertical turbulence mixing, the rates of changes in scalars are different with height. In order to calculate $F_s$ accurately, the differences should be considered using scalar profile measurement. However, most of flux sites for agricultural lands in Asia do not operate profile system and estimate $F_s$ using single-level scalars from eddy covariance system under the assumption that the rates of changes in scalars are constant regardless of the height. In this study, we measured $F_c$ and $F_s$ of $CO_2$, $H_2O$, and air temperature ($T_a$) using eddy covariance and profile system (i.e., the multi-level measurement system in scalars from eddy covariance measurement height to the land surface) at the Chengmicheon farmland site in Korea (CFK) in order to quantify the differences between $F_s$ calculated by single-level measurements ($F_s_{-single}$ i.e., $F_s$ from scalars measured by profile system only at eddy covariance system measurement height) and $F_s$ calculated by profile measurements and verify the errors of NEE caused by $F_s_{-single}$. The rate of change in $CO_2$, $H_2O$, and Ta were varied with height depending on the magnitudes and distribution of sink and source and the stability in the atmospheric boundary layer. Thus, $F_s_{-single}$ underestimated or overestimated $F_s$ (especially 21% underestimation in $F_s$ of $CO_2$ around sunrise and sunset (0430-0800 h and 1630-2000 h)). For $F_{CO_2}$, the errors in $F_s_{-single}$ generated 3% and 2% underestimation of $F_{CO_2}$ during nighttime (2030-0400 h) and around sunrise and sunset, respectively. In the process of nighttime correction and partitioning of $F_{CO_2}$, these differences would cause an underestimation in carbon balance at the rice paddy. In contrast, there were little differences at the errors in LE and H caused by the error in $F_s_{-single}$, irrespective of time.

• Education of Primary School Mathematics
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• v.25 no.1
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• pp.57-79
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• 2022

Current mathematics It is necessary to ensure that ratio and proportion concept is not distorted or broken while being treated as if they were easy to teach and learn in school. Therefore, the purpose of this study is to analyze the activities presented in the textbook. Based on prior work, this study reinterpreted the proportional reasoning task from the proportional perspective of Beckmann and Izsak(2015) to the multiplicative structure of Vergnaud(1996) in four ways. This compared how they interpreted the multiplicative structure and relationships between two measurement spaces of ratio and rate units and proportional expression and proportional distribution units presented in the revised textbooks of 2007, 2009, and 2015 curriculum. First, the study found that the proportional reasoning task presented in the ratio and rate section varied by increasing both the ratio structure type and the proportional reasoning activity during the 2009 curriculum, but simplified the content by decreasing both the percentage structure type and the proportional reasoning activity. In addition, during the 2015 curriculum, the content was simplified by decreasing both the type of multiplicative structure of ratio and rate and the type of proportional reasoning, but both the type of multiplicative structure of percentage and the content varied. Second, the study found that, the proportional reasoning task presented in the proportional expression and proportional distribute sections was similar to the previous one, as both the type of multiplicative structure and the type of proportional reasoning strategy increased during the 2009 curriculum. In addition, during the 2015 curriculum, both the type of multiplicative structure and the activity of proportional reasoning increased, but the proportional distribution were similar to the previous one as there was no significant change in the type of multiplicative structure and proportional reasoning. Therefore, teachers need to make efforts to analyze the multiplicative structure and proportional reasoning strategies of the activities presented in the textbook and reconstruct them according to the concepts to teach them so that students can experience proportional reasoning in various situations.

• Journal of Korea Multimedia Society
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• v.13 no.3
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• pp.378-391
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• 2010

In this paper, it is tested that an individual is able to be identified with finger face images and the results are presented. Special operators, FFG(Facet Function Gradient) masks by which the gradient of a facet function fit on a gray levels of image patches can be computed are used and a new procedure named F-algorithm is introduced to match the finger face images. The finger face image is divided into the equal subregions and each subregions are divided into equal patches with this algorithm. The FFG masks are used for convolution operation over each patch to produce scalar values. These values from a feature matrix, and the identity of fingers is determined by a norm of the elements of the feature matrices. The distribution of the norms shows conspicuous differences between the pairs of hand images of the same persons and the pairs of the different persons. This is a result to prove the ability of discrimination with the finger face image. An identification rate of 95.0% is obtained as a result of the test in which 500 hand images taken from 100 persons are processed through F-algorithm. It is affirmed that the finger face reveals to be such a good biometrics as other hand parts owing to the ability of discrimination and the identification rate.