• Journal of KIISE
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• v.43 no.3
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• pp.389-397
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• 2016

In this paper, we propose a highway safety system that comprises a small number of central servers and smart mobile devices. To implement this system, we constructed a central server that collects GPS location information on cars, whose update messages are decreased via the car location estimation algorithm. The in-car mobile devices use the accelerometer sensors to detect hazardous situations; this information is updated to the central server that relays the information to the corresponding endangered cars via location-based unicast using LTE communication. To evaluate the proposed algorithm, we equipped a mobile device app on a real car and conducted real experiments in various environments such as city streets, rural areas, and highway roads. Furthermore, we conducted simulations to evaluate the propagation of danger information. Finally, we conducted simulated experiments to detect car collisions as well as exceptions, such as falling of the mobile device from the cradle.

• Journal of the Korea Society of Computer and Information
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• v.24 no.12
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• pp.9-16
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• 2019

The goal of this study is to propose an efficient model for recognizing and classifying tree images to measure the accuracy that can be applied to smart devices during class. From the 2009 revised textbook to the 2015 revised textbook, the learning objective to the fourth-grade science textbook of elementary schools was added to the plant recognition utilizing smart devices. In this study, we compared the recognition rates of trees before and after retraining using a pre-trained inception V3 model, which is the support of the Google Inception V3. In terms of tree recognition, it can distinguish several features, including shapes, bark, leaves, flowers, and fruits that may lead to the recognition rate. Furthermore, if all the leaves of trees may fall during winter, it may challenge to identify the type of tree, as only the bark of the tree will remain some leaves. Therefore, the effective tree classification model is presented through the combination of the images by tree type and the method of combining the model for the accuracy of each tree type. I hope that this model will apply to smart devices used in educational settings.

• Science of Emotion and Sensibility
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• v.10 no.4
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• pp.555-569
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• 2007

Ubiquitous computing environment is the new surroundings, currently being realized by modern technology. Since previous usability tests are not suitable for this new technological environment, new research on psychological factors needs to be conducted. The evaluation of service scenarios also will be required in tandem with traditional usability tests of operation devices. Consequently, this study classified usability factors from a scenario perspective and was conducted with a focus on the psychological elements of controllability from a mechanical perspective. Study 1 reclassified the factors of existing usability tests according to similarity and application scenarios, and ten important groups of factors were newly created. Study 2 focused specifically on the design side of a device and showed that the degree of familiarity with the ubiquitous computing device and its complexity brought about a difference in perceived controllability of the device.

• Science of Emotion and Sensibility
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• v.8 no.3
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• pp.277-290
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• 2005

The purpose of this study is to develope a design prototype of 'Smart Battle Jacket' for the future soldier system. Future battle field is supposed to be the place where the information is the most important. Future soldiers are also supposed to get digital devices to have more possibility of survival in the battle field. To design the smart battle jacket that has digital devices inside, it's needed to forecast the body sizes and shape of the future soldiers, to research the human bodies and movements, and to study the functions of the digital devices and the relationship between the bodies and the devices. The usability of the 1st model for the Smart battle jacket had been tested, and the model had been corrected by the results from the test. After all, a smart battle jacket design prototype for the future soldier system has been developed.

• Journal of KIISE:Computing Practices and Letters
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• v.11 no.4
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• pp.368-380
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• 2005

File systems for flash memory that is widely used as a storage device for mobile devices should provide not only high-performance data reads and writes but also a guarantee on the data integrity even on a power failure. In this paper, we explain the design and implementation of a file system for flash memory that considers flash memory's physical characteristics and the data layout in the file system to give an optimized write performance. This file system guarantees the reliability against various system failures including a power failure by using the transaction concept in write processing. In addition, the file system minimizes the memory usage by using a simple static mapping. In the paper, we also describe the implementation of the file system and compare its performance with other existing flash memory ille systems.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.31 no.4
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• pp.617-635
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• 2021

Internet of Things (IoT) devices connected to the network without appropriate security solutions have become a serious security threat to ICT infrastructure. Moreover, due to the nature of IoT devices, it is difficult to apply currently existing security solutions. As a result, IoT devices have easily become targets for cyber attackers, and malware attacks on IoT devices are actually increasing every year. Even though several security solutions are being developed to protect IoT infrastructure, there is a great risk to apply unverified security solutions to real-world environments. Therefore, verification tools to verify the functionality and performance of the developed security solutions are also needed. Furthermore, just as security threats vary, there are several security solution s that defend against them, requiring suitable verification tools based on the characteristics of each security solution. In this paper, we propose an high-speed malware propagation tool that spreads malware at high speed in the IoT infrastructure. Also, we can verify the functionality of the security solution that detect and quickly block attacks spreading in IoT infrastructure by using the high-speed malware propagation tool.

• Asia-pacific Journal of Multimedia Services Convergent with Art, Humanities, and Sociology
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• v.7 no.7
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• pp.935-944
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• 2017

As augmented reality technology has developed, various augmented reality contents can be seen in real life, and the performance of mobile device is improved, so augmented reality technology can be used even without special device. As a result, a training system, guidance system and a museum art guide system based on augmented reality technology are emerging, and interest in augmented reality is also increasing. However, the existing guidance systems using a single mobile device have limitations in terms of the user experience (UX) because the camera of the device limits the field of view or the two hands are not free and the user input is difficult. In this paper, we compare augmented reality based guidance systems for Rubik's Cube using tablet and HMD to improve the constraint of user experience of such a single mobile device, and find elements that positively improve user experience. After that, we evaluate whether the user experience is actually improved through the user experience comparison test and the questionnaire.

• Journal of the Korean Chemical Society
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• v.66 no.2
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• pp.96-106
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• 2022

The purpose of this study is to investigate the effect of science-centered convergence class program using realistic contents such as virtual reality and augmented reality on class satisfaction, scientific attitudes and the perception of the gifted students in middle school. After developing the convergence class program including realistic contents using smart devices, we applied it to the gifted students. We analyzed the class satisfaction, scientific attitude and perception of the gifted students through questionnaires. In addition, a survey was conducted on the pre-teachers to investigate and analyze the class satisfaction, scientific attitude of the science class program to students and the perception of science classes using realistic contents. As a result, both students and pre-teachers were positively aware of class satisfaction by science class program using realistic contents. In particular, it was positive in that the class can induce learning motivation and interest. On the other hand, it was pointed out that the low-quality App and lack of infra for smart devices were disadvantages. In addition, pre-teachers lack confidence and information about class using the realistic contents, but they recognize the need of classes using realistic contents for students and education for pre-teachers. Based on this, it obtained suggestions on the preparation of facilities and equipment in schools for future education, development of contents that can be used for convergence class, development of programs and teaching·learning materials using realistic contents, and education for pre-teachers.

• Journal of the Korean Applied Science and Technology
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• v.37 no.6
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• pp.1798-1805
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• 2020

This study attempted to numerically verify specific effects on skin condition improvement by measuring and comparing changes in skin conditions such as pores, wrinkles, and sebum of LED masks for beauty devices with low output among light sources. 18 healthy women (4 weeks in the control group and 4 weeks in the experimental group) were conducted once a week for 8 weeks. As a result of measuring the skin condition of pores, wrinkles, and sebum, it was confirmed that the skin condition improved significantly as the LED irradiation progressed, and the difference between the groups by measurement period of the experimental group and the control group also showed significant differences in pores, wrinkles, and sebum (p< .001, p<.05). This is meaningful in that it can be presented as clinical information and quantitative data by preparing continuous data in an academic sense by proving the effect of improving the LED mask as a beauty device. It is also suggested that in the future, follow-up studies to prove more effective skin improvement will be conducted.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.17 no.1
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• pp.36-48
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• 2021

As the material aging of nuclear power plants has been progressing in domestic and overseas, crack growth becomes one of the most important issues. In this respect, the crack growth assessment has been considered an essential part of structural integrity. The crack growth assessment for nuclear power plants has been generally performed based on ASME B&PV Code, Sec. XI but the idealization of crack shape and the conservative solutions of stress intensity factor (SIF) are used. Although finite element analysis (FEA) based on iterative crack growth analysis is considered as an alternative method to simulate crack growth, there are yet no guidelines to model the crack-tip spider-web mesh for such analysis. In this study, effects of various meshing factors on FE SIF calculation are systematically examined. Based on FEA results, proper criteria for spider-web mesh in crack-tip are suggested. The validation of SIF calculation method through mapping initial stress field is investigated to consider initial residual stress on crack growth. The iterative crack-tip modeling program to simulate crack growth is developed using the proposed criteria for spider-web mesh design. The SIF results from the developed program are validated by comparing with those from technical reports of other institutes.