• Transactions of the Korean Society of Mechanical Engineers A
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• v.37 no.12
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• pp.1453-1463
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• 2013

In this study, we investigated the effect of the indenter geometry on the crack characteristics by indentation cracking test and FEA. We conducted various cohesive finite element simulations based on the findings of Lee et al. (2012), who examined the effect of cohesive model parameters on crack size and formulated conditions for crack initiation and propagation. First, we verified the FE model through comparisons with experimental results that were obtained from Berkovich and Vickers indentations. We observed whether nonsymmetrical cracks formed beneath the surface during Berkovich indentation via FEA. Finally, we examined the relation between the crack size and the number of cracks. Based on this relation and the effect of the indenter angle on the crack size, we can predict from the crack size obtained with an indenter of one shape (such as Berkovich or Vickers) the crack size for an indenter of different shape.

• Proceedings of the Korea Information Processing Society Conference
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• 2010.04a
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• pp.510-513
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• 2010

Color is basically composed of hue, saturation and value. Many objects are made up with color. When people see color, they feel different emotion because of different combination of hue, saturation and value of different colors. Thus, people feel different feeling about the taste of food depending on its color. Thus, by analyzing what color makes people feel tasty about food, we can make food to look more delicious. When people take pictures of food, theyusually do not consider this into account. However if we apply this technology into taking pictures of food, we can make the food look more delicious. This technology can be applied when people want to upload pictures of food in blog, homepage and twitter and so on. In this paper, we analyze the feelings of color of people and then choose the best color combination to present food. After that we change the original image into the new one based on the analysis of color. This way, we can reflect each user's preference.

• Journal of Korea Multimedia Society
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• v.8 no.10
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• pp.1403-1410
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• 2005

The synchronization problem is directly related to the quality of service in multimedia communication and especially in real-time communication. In this study, we found the cause of clock fluctuation between encoder and decoder in MPEG-2 system layer was that the standard decoder design only considered a fixed time delay component. To solve it, we proposed Extended-SRTS algorithm, which uses STC as service clock by synchronizing transport stream. As the result, we can improve the effect of frequency-drift, time-varying-network-jitter and packing-jitter and so on And by virtue of this algorithm, we can make low the dependency of network clock, which makes easy to synchronize and connect transparently at the ends point, we expect the proposed algorithm can be widely applied to the field of real -time multimedia communications.

• Journal of Internet Computing and Services
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• v.11 no.2
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• pp.1-15
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• 2010

The damage of safety accidents at home can be minimized by preventing accidents in advance as well as by coping with the accidents promptly through the help of safety management system. In this paper, we identify several services to prevent and cope with the accidents that may occur at home by leveraging sensors and wireless network technology available at home network environments. In order to provide these services, we propose a context-aware system for safety management at home. The proposed system awares the dangerous situations through the information collected by the sensors in home network environment. The proposed system tries to not only prevent the accidents but also to cope with the situations using the information of rescue targets and the location where the accident occurs. We evaluate the appropriateness of sensors by implementing the proposed environments. Through OPNET simulation experiments, we also measure the amount of network traffic in order to confirm that the bandwidth of IEEE 802.15.4 is enough for the proposed system. Finally, we determine more appropriate wireless data transmission mechanism with respect to the end-to-end delay and battery consumption for the proposed system.

• Journal of the Korean Vacuum Society
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• v.2 no.2
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• pp.152-160
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• 1993

In this study, we have investigated the influence of sputtering conditions (Ar pressure input powers, substrates) on coercivity and microstructures of GdFe, Co, CoCr thin films produced by the method of DC magnetron sputtering. In GdFe films, we have observed that the Gd atomic ratio was decreased with the deposition rate, and deposition rate decreased with the pressure of Ar gas and the increased linearly with input power. It was also observed that the coercivity of thin films was increased with input power. In Co films, we have investigated the deposition was increased and the Co thin film became finer structure with the increase in the input power, was increased and the Co thin film became finer structure with the increase in the input power, and the deposition rate was decreased with the pressure of Ar gas. In CoCr films, we have investigated the effects of substrates on the coercivity $(H_c)$ and the microstructure. We have found that the substrates plays a crucial role in the microstructure and the coercivity $(H_c)$.

• Journal of The Korean Association of Information Education
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• v.19 no.4
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• pp.441-448
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• 2015

This paper describes about a software implementation for class analysis and quantization based on our video synchronization method. We proposed a new indexing method, synchronization strategies, and data structure for our analyzer implementation. We implemented a class video analyzer using intelligent multimedia technologies which can play class video selectively. Our proposed method analyzes class videos depending on the time schedule composed of introduction, development and summary stages. We apply our analysis filters to the class videos in the predefined regular intervals. We experimented on the synchronization performance of our proposed method and software. In the experimental, we could demonstrate the effectiveness and practicality of our class analyzing method within the margin of error.

• Journal of the Korean Data and Information Science Society
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• v.23 no.1
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• pp.121-129
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• 2012

Association rule mining searches for interesting relationships among items in a given database. Currently, study of the constraint-based association rules are underway by many researchers. When we create relation rule, we can often find a lot of rules. Of this rules, we can find rule that direct relativity by marginally conditional variables (intervening variable, external variable) does not exist. In such a case, this association rule can be considered insignificant. In this study, we want to study for association rules creation using marginally conditional variable. The result of this study can find meaningless association rules. Also, we can understand more exactly the relationships between variables.

• Journal of Elementary Mathematics Education in Korea
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• v.22 no.4
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• pp.331-368
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• 2018

This study is derived from a student who can add without knowing the addition principle. To understand where the student's response come from, we came to analyse the curriculum contents of natural numbers, decimals and fractions addition principle. At the same time, we surveyed two different school of forty six sixth grade participants with questionnaires to determine whether it is a problem of the student or an universal one. As a result, we found that there is a room for improvement in the addition and connections of addition. We propose appropriate instructional method regarding connections of addition and addition principle of natural numbers, decimals and fractions. The conclude there is a close relation and differences among the principles of natural numbers, decimals and fractions in the proposed instructional method. Therefore, we need to consider and instruct the differences of the number expansion.

• CRM연구
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• v.1 no.1
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• pp.49-69
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• 2006

Previous studies, Technology Acceptance Model (TAM) and Post Acceptance Model (PAM) have a little limitation in time series analysis. To solve this limitation, we used system dynamics as research methodology and designed simulation model based on TAM and PAM. Moreover, we designed new simulation model which can analyize time series data in customers' demand change from initial acceptance to post acceptance. This study targeted domestic mobile phone market. The simulation results showed that diffusion graph was similar to real data. That means we validated our simulation model. Since the simulation model offers the graph of customer's demand change by time, so it can be useful as a leaning tool. Therefore, we think this study helps IT companies use the model for forecasting of market demand.

• The Korean Journal of Applied Statistics
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• v.27 no.3
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• pp.373-386
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• 2014

A word cloud is a visualization of word frequency in a given text. The importance of each word is shown in font size or color. This plot is useful for quickly perceiving the most prominent words and for locating a word alphabetically to determine its relative prominence. With dynamic graphics, we can find the changing pattern of prominent words and their frequencies according to the changing selection of chapters in a given text. We can define the word frequency matrix. In this matrix, rows are chapters in text and columns are ranks corresponding to word frequency about the words in the text. We can draw the word frequency matrix plot with this matrix. Dynamic graphic can indicate the changing pattern of the word frequency matrix according to the changing selection of the range of ranks of words. We execute an English Bible text visualization using word clouds and dynamic graphics technology.