• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.10
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• pp.2359-2366
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• 2015

In accordance with development of many smart phone applications, the importance of keypad that can be used in smart phone has been increasing. In this paper, we design the Hangul smart phone keypad to type a Hangeul characters more efficiently by considering the characteristics of the Hangul characters based on the existing research on smart phones keypad. The proposed keypad in this paper, when we placed the letters on the keyboard, minimizes the travel distance by using the frequency of characters and the associated frequency between vowel and consonant. In addition, we define an assessment model for evaluating the performance of the keypad and verify efficiency of the proposed keypad. According to the result of the experiment, the proposed keypad is more efficient than other keypads.

• KIPS Transactions on Software and Data Engineering
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• v.2 no.9
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• pp.615-620
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• 2013

With the development of smartphones, the number of applications for smartphone increases sharply. As a result, users need to try several times to find their favorite apps. In order to solve this problem, we propose a recommendation system to provide an appropriate app list based on the user's log information including time stamp, location, application list, and so on. The proposed approach learns three recommendation models including Naive-Bayesian model, SVM model, and Most-Frequent Usage model using temporal and spatial attributes. In order to figure out the best model, we compared the performance of these models with variant features, and suggest an hybrid method to improve the performance of single models.

• Journal of KIISE:Software and Applications
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• v.41 no.8
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• pp.598-604
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• 2014

In this paper, we develop stepwise regression data envelopment model to select important variables. We formulate null hypothesis to understand the importance of each variable and use Kruskal-Wallis test for this purpose. If the Kruskal-Wallis test does reject the null hypothesis this will imply there is significant fluctuation in the efficiency score relative to base model. And therefore we have to further check the pair of variables that causes the fluctuation in order to determine its importance using Conover-Inman test. The proposed models helps understand the extent of misclassification decision making units as efficient/inefficient when variables are retained or discarded alongside provides useful managerial prescription to make improvement strategies.

• Journal of KIISE:Software and Applications
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• v.30 no.1_2
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• pp.129-139
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• 2003

The PC cluster architecture is considered as a cost-effective alternative to the existing supercomputers for realizing a high-performance information retrieval (IR) system. To implement an efficient IR system on a PC cluster, it is essential to achieve maximum parallelism by having the data appropriately distributed to the local hard disks of the PCs in such a way that the disk I/O and the subsequent computation are distributed as evenly as possible to all the PCs. If the terms in the inverted index file can be classified to closely related clusters, the parallelism can be maximized by distributing them to the PCs in an interleaved manner. One of the goals of this research is the development of methods for automatically clustering the terms based on the likelihood of the terms' co-occurrence in the same query. Also, in this paper, we propose a method for duplicate distribution of inverted index records among the PCs to achieve fault-tolerance as well as dynamic load balancing. Experiments with a large corpus revealed the efficiency and effectiveness of our method.

• Spatial Information Research
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• v.17 no.3
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• pp.371-379
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• 2009

Recently, GPU (Graphics Processing Unit) has been improved rapidly on the need of speed for gaming. As a result, GPU contains multiple ALU (Arithmetic Logic Unit) for parallel processing of a lot of graphics data, such as transform, ray tracing, etc. Therefore, this paper proposed a technique for parallel processing of spatial data using GPU. Spatial data consists of multiple coordinates, and each coordinate contains value of x and y axis. To display spatial data graphics operations have to be processed to large amount of coordinates. Because the graphics operation is identical and coordinates are multiple data, SIMD (Single Instruction Multiple Data) parallel processing of GPU can be used for processing of spatial data to improve performance. This paper implemented SIMD parallel processing of spatial data using two kinds of SDK (Software Development Kit). CUDA and ATI Stream are used for NVIDIA and ATI GPU respectively. Experiments that measure time of calculation for graphics operations are carried out to observe enhancement of performance. Experimental result is reported that proposed method can enhance performance up to 1,162% for graphics operations. The proposed method that uses parallel processing with GPU for spatial data can be generally used to enhance performance for applications which deal with large amount of spatial data.

• Membrane Journal
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• v.32 no.1
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• pp.57-65
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• 2022

Recently, computer simulation research has been rapidly increasing due to the development of computer and software technology. In particular, various computational simulation results related to polymers, which were previously limited by problems of the number of atoms and model size, are being published. In this study, a study was conducted to analyze the mechanical properties, one of the important properties for using a polymer material as a membrane, using molecular dynamics (MD) simulation. To this end, polyethylene (PE) and polystyrene (PS), which are commercial polymer materials with widely reported related properties, were selected as polymer models and the tensile properties of each polymer were compared through the difference in main chain length. Through the density, radius of gyration, and scattering analysis, it was found that the model produced in this study was in good agreement with the mechanical property trends obtained in the actual experiment. It is expected to enable the prediction of mechanical properties of various polymer materials for membrane fabrication.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.8 no.5
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• pp.1050-1057
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• 2004

The purpose of study is development of a fuzzy controller which independent of a computer and its software for fuzzy control of servo system. This paper describes a method of approximate reasoning for fuzzy control of servo system, based on decomposition of $\alpha$-level fuzzy sets, It is propose that fuzzy logic algorithm is a body from fuzzy inference to defuzzificaion in cases where the output variable u directly is generated PWM. The effectiveness of quantified $\alpha$-levels on input/output characteristics of fuzzy controller and output response of DC servo system is investigated. It is concluded that $\alpha$-cut 4 levels give a sufficient result for fuzzy control performance of DC servo system. The experimental results shows that the proposed hardware method is effective for practical applications of DC servo system.

• The Journal of the Convergence on Culture Technology
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• v.9 no.3
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• pp.811-816
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• 2023

With the emergence of a climate crisis, climate disasters have recently been clearly felt in Korea. In particular, the typhoon 'Hinnamno' in the summer of 2022 made many people feel a sense of crisis with its formidable power. In this situation, children are likely to suffer great damage even in small crises due to their lack of experience and ability to cope with disaster situations. In this paper, we introduce a disaster response learning application that supports children's disaster response training. Designed based on research results on situational learning theory and child disaster safety education, this system produces various episodes and trains them to encounter disaster situations. Children can participate in the episode by choosing options during the episode, which is reflected in the picture diary after the episode is completed. By providing information naturally in the picture diary, children can access how to cope with disaster situations. Through this system, children are expected to develop their judgment in disaster situations that they can encounter and have the ability to secure basic safety outside of adult help.

• Journal of Internet Computing and Services
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• v.14 no.4
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• pp.35-42
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• 2013

Nowadays many tasks are performed using the Web. Accordingly, many web-based application systems with various and complicated functions are being requested. In order to develop such web-based application systems efficiently, object-oriented analysis and design methodology is used, and Java EE(Java Platform, Enterprise Edition) technologies are used for its implementation. The security issues have become increasingly important. For such reasons, Java EE provides mechanism related to security but it does not provide interconnections with object-oriented analysis and design methodology for developing web application system. Consequently, since the security method by Java EE mechanism is implemented at the last step only, it is difficult to apply constant security during the whole process of system development from the requirement analysis to implementation. Therefore, this paper suggests an object-oriented analysis and design methodology emphasized in the security for secure web application systems from the requirement analysis to implementation. The object-oriented analysis and design methodology adopts UMLsec, the modeling language with an emphasis on security for the requirement analysis and system analysis & design with regard to security. And for its implementation, RBAC (Role Based Access Control) of servlet from Java EE technologies is used. Also, the object-oriented analysis and design methodology for the secure web application is applied to online banking system in order to prove its effectiveness.

• Journal of Space Technology and Applications
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• v.1 no.1
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• pp.23-32
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• 2021

The high-level Space Situational Awareness (SSA) objective is to provide to the users dependable, accurate and timely information in order to support risk management on orbit and during re-entry and support safe and secure operation of space assets and related services. Therefore the risk assessment for the re-entry of space objects should be managed nationally. In this research, the Software for Re-Entry Prediction of space objects (SREP) was developed for national SSA system. In particular, the rate of change of the drag coefficient is estimated through a newly proposed Drag Scale Factor Estimation (DSFE), and is used for high-precision orbit propagator (HPOP) up to an altitude of 100 km to predict the re-entry time and position of the space object. The effectiveness of this re-entry prediction is shown through the re-entry time window and ground track of space objects falling in real events, Grace-1, Grace-2, Tiangong-1, and Chang Zheng-5B Rocket body. As a result, through analysis 12 hours before the final re-entry time, it is shown that the re-entry time window and crash time can be accurately predicted with an error of less than 20 minutes.