• Current Photovoltaic Research
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• v.8 no.1
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• pp.17-26
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• 2020

It is clear that monocrystalline Silicon (Si) ingots are the key raw material for semiconductors devices. In the present industries markets, most of monocrystalline Silicon (Si) ingots are made by Czochralski Process due to their advantages with low production cost and the big crystal diameters in comparison with other manufacturing process such as Float-Zone technique. However, the disadvantage of Czochralski Process is the presence of impurities such as oxygen or carbon from the quartz and graphite crucible which later will resulted in defects and then lowering the efficiency of Si wafer. The heat transfer plays an important role in the formation of Si ingots. However, the heat transfer generates convection in Si molten state which induces the defects in Si crystal. In this study, a crystal growth simulation software was used to optimize the Si crystal growth process. The furnace and system design were modified. The results showed the melt-crystal interface shape can affect the Si crystal growth rate and defect points. In this study, the defect points and desired interface shape were controlled by specific crystal growth rate condition.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2009.01a
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• pp.664-667
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• 2009

There is strong demand to create wearable PC systems that can support the user outdoors. When we are outdoors, our movement makes it impossible to use traditional input devices such as keyboards and mice. We propose a hand gesture interface based on image processing to operate wearable PCs. The semi-transparent PC screen is displayed on the head mount display (HMD), and the user makes hand gestures to select icons on the screen. The user's hand is extracted from the images captured by a color camera mounted above the HMD. Since skin color can vary widely due to outdoor lighting effects, a key problem is accurately discrimination the hand from the background. The proposed method does not assume any fixed skin color space. First, the image is divided into blocks and blocks with similar average color are linked. Contiguous regions are then subjected to hand recognition. Blocks on the edges of the hand region are subdivided for more accurate finger discrimination. A change in hand shape is recognized as hand movement. Our current input interface associates a hand grasp with a mouse click. Tests on a prototype system confirm that the proposed method recognizes hand gestures accurately at high speed. We intend to develop a wider range of recognizable gestures.

• Proceedings of the ESK Conference
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• 1997.10a
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• pp.249-259
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• 1997

As the gap between competing products narrows in terms of performance and quality, the product usability is rapidly becoming a new dimension of product design as the key to offering distinctive value to the customer. Because the user interface is important, not only for the user but also for the efficiency of te whole organiation, system designers require increasingly precise evaluation methods to determine how effective and usable human-product interface is. In this study a new methodology named usability analysis diagram(UAD), for evaluating usability of human-product interface systematically, was developed. UAD is a top-down flow diaagram of a human-product interaction, in ehichfour basic elements - perception, understanding, intellectual decision and action - were classified and then represented by a particular symbol for each. The usability of the product is assessed by the frequency of each symbol in a diagram which represents a sequence of cognitive and physical activities of users during the use of the product, and by the level of difficulty that is classif- ied in three levels in terms of easiness of perception, understanding and action. In order to test validity of the proposed UAD in a real situation, a case study was performed on two different cameras, automatic and manual, and their usability was successfully evaluated and compared.

• Journal of the Korean Institute of Intelligent Systems
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• v.21 no.1
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• pp.106-111
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• 2011

Video-based detection and tracking of moving objects has been widely used in real-time monitoring systems and a videoconferencing. Also, because object motion tracking can be expanded to Human-computer interface and Human-robot interface, Moving object tracking technology is one of the important key technologies. If we can track a specified object in an environment of multiple moving objects, then there will be a variety of applications. In this paper, we introduce a specified object motion tracking using particle filter. The results of experiments show that particle filter can achieve good performance in single object motion tracking and a specified object motion tracking in an environment of multiple moving objects.

• Proceedings of the KIEE Conference
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• 1987.07a
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• pp.465-468
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• 1987

This paper describes a model to calculate the equilibrium electron density of MODFET at the interface that takes into account the simultaneous shallow and deep level in the Al-GaAs layer. In the present study we have made an investigation of the interface electron density with different values of the AlGaAs doping density and spacer layer thickness, considering simultaneously two doner levels. In this case, the ratio of the shallow to the deep donor concentraction is considered. From the comparison with early experimental results we could find the deep level and that the deep donor concentration is about 50% with the Al mole fraction X ${\sim}0.3$, activation energy Edx=65meV, temperature $77^{\circ}K$ and spacer thickness range $50A{\sim}100A$. Also we have investigated the effect of the temperature. As temperature increase, at critical mole fraction X the nature of the donor concentration changes from $\Gamma$ to L and X.

• Journal of Biosystems Engineering
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• v.38 no.1
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• pp.25-32
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• 2013

Purpose: The objective of this study is to develop a data middleware for u-IT convergence in agricultural environment monitoring, which can support non-standard data interfaces and solve the compatibility problems of heterogenous sensor networks. Methods: Six factors with three different interfaces were chosen as target data among the environmental monitoring factors for crop cultivation. PostgresSQL and PostGIS were used for database and the data middleware was implemented by Python programming language. Based on hierarchical model design and key-value type table design, the data middleware was developed. For evaluation, 2,000 records of each data access interface were prepared. Results: Their execution times of File I/O interface, SQL interface and HTTP interface were 0.00951 s/record, 0.01967 s/record and 0.0401 s/record respectively. And there was no data loss. Conclusions: The data middleware integrated three heterogenous sensor networks with different data access interfaces.

• Journal of Korea Multimedia Society
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• v.12 no.12
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• pp.1736-1744
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• 2009

In this paper, we present an animation sketching system using a two layered approach. Animation sketching is a popular technique to create informal animations but it is often suffered by the low-quality output due to a trade-off between convenience and complexity. Our aim is to support sketching practical animation scenes easily and fast while not complicating the simple sketching interface. The key idea is to combine two conceptual stop motion layers, a whiteboard and cutout animation layer, in a seamless interface. As a background, the whiteboard animation layer handles stroke-oriented objects, while the cutout animation layer takes charge of transform-oriented objects. We found that this approach enables users to express more complicated animation fast while still maintaining a concise sketching interface. We demonstrate the usability and flexibility through resulting animations from user experiments.

• IEMEK Journal of Embedded Systems and Applications
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• v.3 no.4
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• pp.207-217
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• 2008

A novel scheme is presented for Traffic Encryption Key (TEK) rekeying with low communication overhead for an Internet Protocol television (IPTV) conditional access system over Data-Over-Cable Service Interface Specifications (DOCSIS) 3.0. The proposed scheme utilizes the DOCSIS system synchronization for periodic TEK rekeying instead of a conventional TEK rekeying negotiation process. Analysis shows that the communication overhead is only 0.012 Kbps when TEK rekeying frequency is 1 second.

• BMB Reports
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• v.45 no.8
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• pp.452-457
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• 2012

Diketoreductase (DKR) from Acinetobacter baylyi contains two tryptophan residues at positions 149 and 222. Trp-149 and Trp-222 are located along the entry path of substrate into active site and at the dimer interface of DKR, respectively. Single and double substitutions of these positions were generated to probe the roles of tryptophan residues. After replacing Trp with Ala and Phe, biochemical and biophysical characteristics of the mutants were thoroughly investigated. Enzyme activity and substrate binding affinity of W149A and W149F were remarkably decreased, suggesting that Trp-149 regulates the position of substrate at the binding site. Meanwhile, enzyme activity of W222F was increased by 1.7-fold while W222A was completely inactive. In addition to lower thermostability of Trp-222 mutants, molecular modeling of the mutants revealed that Trp-222 is vital to protein folding and dimerization of the enzyme.

• Journal of the Korean Ceramic Society
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• v.53 no.6
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• pp.665-669
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• 2016

$TiO_2/BiVO_4$ layered films were prepared by sol-gel and spin coating methods. X-ray diffraction (XRD), scanning electron microscopy (SEM) and Uv-vis spectroscopy were used to investigate the crystal structure, morphology and ultraviolet-visible absorption of the $TiO_2/BiVO_4$ films. The photocatalytic activity of the prepared films was inspected according to the degradation of methylene blue. The results show that the prepared films present a net chain structure; the absorption band edge had obvious red shift. The degradation of the methylene blue solution was about 80% after 300 mins using $TiO_2/BiVO_4$ layered films under visible light, which was stronger than when using only pure $TiO_2$ film and $BiVO_4$ film.