• Journal of Korean Elementary Science Education
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• v.28 no.3
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• pp.321-330
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• 2009

This study investigated the effects of teaching-learning lesson plan using cognitive acceleration instructional strategies applied to the unit, 'The Light and Shadow' in elementary school. Two classes of the second grade elementary students (N=63) in Chungcheongbukdo districts were assigned to control and treatment groups each, and were taught about 'The Light and Shadow' for 8 class hours. For the treatment group, teaching-learning lesson plan using cognitive acceleration instructional strategies developed by this research was applied. The traditional instruction by textbook and teacher's guides was used for the control group. All students were tested with the test for concept of the shadow and the test for academic achievement about the unit. As the result of the post-test, the scores of the treatment group were higher than those of the control group. However, it was not statistically meaningful difference. The scores of the treatment group were significantly higher than those of the control group in the delayed-post-test for concept of the shadow. No significant interaction was observed with respect to the students' gender, instruction and pre-level for the concept of the shadow. Data analysis indicated that the scores of the treatment group were significantly higher than those of the control group in the post-test and delayed- post-test for the concept of the shadow in the area of object permanence. Our research work shows the effectiveness of the teaching-learning lesson using cognitive acceleration instructional strategies for the development for concept of the shadow for elementary school students, and suggests the necessity for this kind of teaching-learning program in the fields.

• The Journal of Asian Finance, Economics and Business
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• v.7 no.5
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• pp.73-80
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• 2020

Tax is the main revenue of Government, so fighting tax evasion and sustainable growth have been the primary macroeconomic goals being pursued by every developing country, Vietnam included. The existence and development of the shadow economic sector are synonymous with the national budget losing out. In Vietnam, foreign direct investment projects do not promote economic growth and is also a sector that gives way to tax evasion.The purpose of this study is to investigate the impact of foreign direct investment, the quality of the informal institution on the size of the shadow economy in Vietnam, during the period 1991-2015. By applying the Autoregressive Distributed Lag approach and Toda and Yamamoto test, we found evidence to conclude that the quality of the informal institution harms the size of the shadow economy. The results of the causality test show that there is a unidirectional causality running from the shadow economy and the quality of the informal institution to foreign direct investment attraction in Vietnam. Political solutions need to be implemented carefully to counter the harmful effects of the shadow economy. Policymakers should adopt several economic policies to improve the 'human capital' and drive the shadow economy into the formal economy.

• Journal of Korea Game Society
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• v.13 no.3
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• pp.85-94
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• 2013

In this paper, we propose a scheme to reduce the number of shadow tests conducted during rendering of ray tracing. The shadow test is a very important process in ray tracing to generate photo-realistic images. In the rendering phase, the ray tracer determines whether to cull the shadow test based on information calculated from a shadow test conducted on the kd-tree in the preprocessing phase. In conventional rendering process, the proposed method can be used with little modification. The proposed method is suitable for a static scene, in which the geometry and light source does not change in the same manner as it does in the conventional method. The validity of the proposed scheme is verified and its performance is evaluated during cycle-accurate simulation. Through experiment results, we found that we could reduce up to 17% of the shadow test.

• Journal of Internet Computing and Services
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• v.21 no.5
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• pp.49-56
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• 2020

Detecting shadows in images and restoring or removing them was a very challenging task in computer vision. Traditional researches used color information, edges, and thresholds to detect shadows, but there were errors such as not considering the penumbra area of shadow or even detecting a black area that is not a shadow. Deep learning has been successful in various fields of computer vision, and research on applying deep learning has started in the field of shadow detection and removal. However, it was very difficult and time-consuming to collect data for network learning, and there were many limited conditions for shooting. In particular, it was more difficult to obtain shadow data from buildings and satellite images, which hindered the progress of the research. In this paper, we propose a method for generating shadow data from buildings and satellites using Unity3D. In the virtual Unity space, 3D objects existing in the real world were placed, and shadows were generated using lights effects to shoot. Through this, it is possible to get all three types of images (shadow-free, shadow image, shadow mask) necessary for shadow detection and removal when training deep learning networks. The method proposed in this paper contributes to helping the progress of the research by providing big data in the field of building or satellite shadow detection and removal research, which is difficult for learning deep learning networks due to the absence of data. And this can be a suboptimal method. We believe that we have contributed in that we can apply virtual data to test deep learning networks before applying real data.

• Tunnel and Underground Space
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• v.3 no.2
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• pp.109-117
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• 1993

The existence and exact location of cavity is very important for the stability of the large underground storage house or building. Numerical method such as finite element method and finite diference methods are widely used because of model's complexity. Preliminary tests such as calculation step test, mesh size test and model size test were tried. Upper shadow zone and lower shadow zone can be calculated from 50% amplitude level of measuring data. From these statistical methods, the calculatied position of cavity coincided nearly with actual position of model testing cavity.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2009.10a
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• pp.574-578
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• 2009

Real-time object detection for distinguishing a moving object of interests from the background image in still image or video image sequence is an essential step to a correct object tracking and recognition. Moving cast shadow can be misclassified as part of objects or moving objects because the shadow region is included in the moving object region after object segmentation. For this reason, an algorithm for shadow removal plays an important role in the results of accurate moving object detection and tracking systems. To handle with the problems, an accurate algorithm based on the features of moving object and shadow in color space is presented in this paper. Experimental results show that the proposed algorithm is effective to detect a moving object and to remove shadow in test video sequences.

• 제어로봇시스템학회:학술대회논문집
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• 1993.10b
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• pp.251-256
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• 1993

In KACC'91 and '92 conference, we proposed a method of automatically detecting the shape of the faulty holes in a shadow mask by use of CCD ca.mera and image data processing technic. In this method, two adjoining test areas from one image data. of the shadow mask are taken and comparing the shape of holes in these two areas, we can detect the faults in the shadow mask. In this paper, a method is described by use of spatial filtering of effectively finding the faulty holes from the difference image data between the two tested image data. The main role of the filter is to remove sampling errors occurring at the edge of the holes. And the second role is not only to find the existence of faulty holes but also exactly express the shape of faulty holes. Computer simulations and actual experiments with shadow masks have shown that this method of fault detection is very effective for practical use.

• Journal of the Korean Society for Precision Engineering
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• v.19 no.11
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• pp.89-95
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• 2002

A shadow mask inside the Braun tube of a TV is sustained by springs attached to the glass panel, its vibration cause the picture image to discolor, which is called the microphonic phenomenon. It is found that it results from resonance when the natural frequency of the shadow mask coincides with that of built-in speaker sound. This paper describes experimental and analytical investigations by using FEM on the vibration problem of the shadow mask assembly. The simulation scheme may be efficiently used to develop a new design for a large-screen flat TV.

• 한국신재생에너지학회:학술대회논문집
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• 2011.11a
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• pp.35.1-35.1
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• 2011

When the wind speed is measured by the met-mast sensor it is distorted due to the shadow effect of tower. In this paper the tower shadow effect is analyzed by a computational fluid dynamics code. First three dimensional modeling and flow analysis of the met-mast system were performed. The results were compared with the available experimental wind-tunnel test data to confirm the validity of the meshes and turbulence model. Two-dimensional model was then developed based on the three-dimensional works and experimental data. 2D analysis for various Reynolds numbers and turbulence strengths were then performed to establish the tower shadow effect database, which can be utilized as correction factors for the measured wind energy.

• Journal of Korea Game Society
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• v.14 no.2
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• pp.77-84
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• 2014

Presence of soft shadow effects from an area light makes virtual scenes look more realistic. However, since computation of soft shadow effects takes a long time, acceleration methods are required to apply it to real-time 3D applications. Many researches assumed that area lights are white rectangles. We suggest a new method which renders soft shadows under the area light source having arbitrary shape and color. In order to approximate visibility test, we use a shadow mapping result near a pixel. Complexity of shadow near a pixel is used to determine degree of precision of our visibility estimation. Finally, our method can present more realistic soft shadows for the area light that have more general shape and color in real-time.