• Nuclear Engineering and Technology
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• v.52 no.11
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• pp.2479-2490
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• 2020

We performed experiments to measure a single-phase upward flow in a 5 × 5 rod bundle with spacer grids using a particle image velocimetry, focusing on the crossflow. The Reynolds number based on the hydraulic diameter and the bulk velocity is 10,000. The ratio of pitch between rods and rod diameter is 1.4 and spacer grid is installed periodically. The turbulence in the rod bundle results from the combination of a forced mixing and natural mixing. The forced mixing by the spacer grid persists up to 10D_h from the spacer grid, while the natural mixing is attributed to the crossflow between adjacent subchannels. The combined effects contribute to a sinusoidal distribution of the time-averaged stream-wise velocity along the lateral direction, which is relatively weak right behind the spacer grid as well as in the gap. The streamwise and lateral turbulence intensities are stronger right behind the spacer grid and in the gap. Based on these findings, we newly defined a modified mixing coefficient as the ratio of the lateral turbulence intensity to the time-averaged streamwise velocity, which shows a spatial variation. Finally, we compared the developed model with the measured data, which shows a good agreement with each other.

• Proceedings of the Korean Information Science Society Conference
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• 2005.11b
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• pp.913-915
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• 2005

임의의 영상에서 얼굴을 검출하는 것은 얼굴을 인식하는데 있어서 선행되어야 할 필수과정이다. 본 논문은 조명의 변화가 심한 컬러영상에서 얼굴을 검출하는 것을 목적으로 한다. 본 논문은 기존의 기하학적 밝기분포 마스크만을 사용한 방법이 조명 변화에 취약한 단점을 보완하는데 중점을 두었다. 히스토그램 평활화(Histogram Equalization : HE)와 감마 크기 보정 (Gamma Intensity Correction : GIC) 방법을 이용해서 조명에 대한 간섭을 줄인 후, 영상 전체에서 피부 영역을 추출하고 이어서 눈 후보들을 검출한다. 검출된 눈 후보들로부터 기하학적 밝기분포 마스크를 적용하여 효과적으로 얼굴 후보들을 찾을 수 있고, 이렇게 찾아진 얼굴 후보들은 주성분분석법(Principal Component Analysis : PCA)를 이용해서 얼굴인지 여부를 판별하게 된다. 본 알고리즘은 조명 밝기 등으로 인해 검출률이 떨어졌던 단점을 보완할 수 있었고, 향후 얼굴 검출 분야에 있어서도 활용 가치가 있을 것으로 생각된다.

• The Journal of Asian Finance, Economics and Business
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• v.7 no.8
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• pp.77-85
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• 2020

The aim of this study is two-fold. Firstly, it attempts to assess the level of management accounting practices (MAPs) in manufacturing companies in Vietnam. Secondly, it purports to explore the impact of potential contingency factors on the current level of MAPs in the sample of studied companies from the industrial sector in Vietnam. The study examines the hypotheses that MAPs in Vietnamese manufacturing firms are affected by a range of contingent variables. A quantitative research was conducted by sending questionnaires to the target respondents that comprise both accountants and managers in 160 manufacturing enterprises in the north of Vietnam. The first main findings from the study reveal that MAPs in Vietnam are mainly traditional rather than contemporary ones, and oriented toward the short-term rather than the long-term. The second main research findings resulted from multiple regression model show that MAPs in Vietnam are significantly affected by company size, commitment of directors, advanced manufacturing technology, and distinct number of products. However, no significant associations are found between MAPs and intensity of competition from the emerging market as hypothesized in this study. Research findings are bases for recommendations to promote the application of contemporary practices and enhance management accounting functions in manufacturing companies in Vietnam.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.6 no.1
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• pp.1-10
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• 1996

A numerical study was conducted on the effects of the cusp magnetic field in 8" silicon single crystal grwoth by Czochralski method. For a damping effects simulation by magnetic field, low reynolds number ${\kappa} - {\varepsilon}$ model was adopted. Symmetrci cusp magnetic field has a effect of damping streamline crystal, is lowerd with the increasing cusp magnetic field intensity. The uniformity of the oxygen concentration was improved. The asymmetirc cusp magnetic field increased the oxygen concentration however, oxygen concentration distribution in the radial direction was remained uniform. Suitable combination of symmetric and asymmetric cusp magnetic fields could give uniform and low oxygen concentration in the axial direction.tion.

• Publications of The Korean Astronomical Society
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• v.21 no.2
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• pp.27-33
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• 2006

Infrared color-color diagram of 10 giant molecular clouds are examined to explore the dust property from the COBE Diffuse Infrared Background Experiment of the 100, 140, and $240{\mu}m$ emission. Four of them, Taurus, Mon OB1, Gem OB1, and Chameleon, show the anti-correlation in $R_{100/140}-R_{140/240}$ plot and the horizontal distribution in $R_{100/240}-R_{140/240}$ plot, which disagree with those of theoretical calculation. These could be explained by the depletion of $100{\mu}m$ and the excess of $140{\mu}m$ emission, though no existing dust model could support them. Mean color temperature of the anti-correlation region appears to be lower than that of the linear region, whose temperatures are 15.3, 17.0 K, respectively. And the linear region shows large dispersion in the plot of intensity relation. Both imply that a star formation would be more active, but not homogeneous, in the linear region compared to the anti-correlation region.

• Transactions of the Korean Society of Mechanical Engineers
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• v.12 no.6
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• pp.1303-1311
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• 1988

Described is method for development of an optical roughness measurement sensor for in-subequality assurance in the precision grinding. Main approach is made based upon the Brckmann's light scattering theory, in which general solutions of the optical scattering behaviour are given under many simplifying assumptions on the model of the surfaces illuminated. For the ground surface, the assumptions are verified through computer simulation and experimental work in order to examine the validity of Beckmann's theory on predicting the optical responses according to the roughness variation. As a result, an optical monitoring strategy is derived which can evaluate the roughness value of the ground surface by statistically detecting the pattern of intensity distribution of the scattered light. Finally, the strategy is proven by comparing with the results using the stylus method.

• Journal of Power Electronics
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• v.18 no.6
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• pp.1920-1929
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• 2018

In order to provide a source for nine phases suitable for 18-pulse ac to dc power, this paper proposes a new structure for a step-up asymmetrical delta-connected transformer for converting three-phase ac power to nine-phase ac power. The design allows for symmetry between the nine output voltages to improve the power quality of the supply current and to minimize the THD. The results show that this new structure proves the equality between the output voltages with $40^{\circ}-{\alpha}$ and $40^{\circ}+{\alpha}$ phase shifting and produces symmetrical output currents. This result in the elimination of harmonics in the network current and provides a simulated THD that is equal to 5.12 %. An experimental prototype of the step-up asymmetrical delta-autotransformer is developed in the laboratory and the obtained results give a network current with a THD that is equal to 5.35%. Furthermore, a finite element analysis with a 3D magnetic field model is made based on the dimensions of the 4kVA, 400 V laboratory prototype three-phase with three-limb delta-autotransformer with a six-stacked-core in each limb. The magnetic distribution flux, field intensity and magnetic energy are carried out under open-circuit operation or load-loss.

• Journal of the Korean Geosynthetics Society
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• v.17 no.4
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• pp.103-108
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• 2018

The fragility curves for CFRD dams are derived in this study for probabilistic damage estimation as a function of a ground motion intensity. The dam crest settlement, which is a widely used damage index, is used for minor, moderate, and extensive damage states. The settlement is calculated from nonlinear dynamic numerical simulations. The accuracy of the numerical model is validated through comparison with a centrifuge test. The fragility curve is represented as a log normal distribution function and presented as a function of the peak ground acceleration. The fragility curves developed in this study can be utilized for real time assessment of the damage of dams.

• Applied Microscopy
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• v.49
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• pp.1.1-1.10
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• 2019

Joints of three-dimensional (3D) rutile-type (r) tin dioxide ($SnO_2$) nanowire networks, produced by the flame transport synthesis (FTS), are formed by coherent twin boundaries at $(101)^r$ serving for the interpenetration of the nanowires. Transmission electron microscopy (TEM) methods, i.e. high resolution and (precession) electron diffraction (PED), were utilized to collect information of the atomic interface structure along the edge-on zone axes $[010]^r$, $[111]^r$ and superposition directions $[001]^r$, $[101]^r$. A model of the twin boundary is generated by a supercell approach, serving as base for simulations of all given real and reciprocal space data as for the elaboration of three-dimensional, i.e. relrod and higher order Laue zones (HOLZ), contributions to the intensity distribution of PED patterns. Confirmed by the comparison of simulated and experimental findings, details of the structural distortion at the twin boundary can be demonstrated.

• The Journal of Asian Finance, Economics and Business
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• v.8 no.3
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• pp.561-573
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• 2021

Knowing how to build and maintain consumer trust is crucial for e-commerce. Despite the number of empirical studies that have explored the factors that influence consumer trust, none of them considers the relative importance of different antecedents and how they interact to influence consumer trust. Therefore, based on the integrated Decision Making Trial and Evaluation Laboratory (DEMATEL) and Interpretive Structural Modeling (ISM) approaches, we establish a hierarchical structural model, which not only demonstrates the intensity of the relationships but also identifies the interdependence among the drivers of consumer trust in E-commerce. The findings confirm that propensity to trust is the most important determinant of consumer trust. The brand-related factors and platform-related factors are prominent in the process of building trust as they influence consumer trust indirectly through propensity to trust. Geographic location, demographic variables, and high security are identified as the root causes that affect consumer trust through other trust antecedents. Furthermore, the findings of this study offer valuable insights into an important element of e-commerce and provide a useful platform for future research. More represented samples and factors are encouraged for further research to ensure research fairness and minimize consumer distrust and uncertainty.