• Journal of the Korean Society of Propulsion Engineers
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• v.23 no.6
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• pp.39-50
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• 2019

Modeling and Simulation(M&S) for a liquid propellant supply system is a technique to predict the performance of components and systems under certain conditions based on mathematical modeling for each component of the engine. In this paper, the basic structure of M&S for the supply system applied to liquid rocket engines was obtained by analyzing the related research conducted. The basic mathematical modeling of components was organized and the characteristics of each study result were analyzed. Based on the analysis and validation results, M&S method of advanced foreign research institutes was also identified, and factors related to its accuracy were described.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.41 no.6
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• pp.13-22
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• 2004

This study proposes a risk analysis methodology for information system security management in which the complexity on the procedure that the existing risk analysis methodology is reduced to the least. The proposed risk analysis methodology is composed of 3 phases as follows: beforehand processing phase, counter measure setting phase, post processing phase. The basic risk analysis phase is a basic security management phase in which fixed items are checked when the information security system is not yet established or a means for the minimum security control is necessary for a short period of time. In the detailed risk analysis phase, elements of asset a vulnerability, and threat are analysed, and using a risk degree production table produced from these elements, the risk degree is classified into 13 cases. In regard to the risk, the 13 types of risk degree will execute physical, administrative, and technical measures through ways such as accepting, rejecting, reducing, and transferring. Also, an evaluation on a remaining risk of information system is performed through a penetration test, and security policy set up and post management phase is to be carried out.

• Journal of the Korean Institute of Intelligent Systems
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• v.13 no.2
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• pp.192-199
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• 2003

Agents in multi-agent systems (MAS ) are required to achieve their own goals. An agent s goal, however, can conflict with others either when agents compete with each other to achieve a common goal or when they have to use a set of limited resources to accomplish agents divergent goals. In either case, agents need to be designed to reach a mutual acceptable state where they can avoid any goal conflicts through negotiation with others to achieve their goals. In this paper, we consider a BDI agent architecture where belief, desire, and intention are the three major components for agents mental attitudes and represent resource-bounded BDI agents in logic programming framework. We propose a negotiation algorithm for BDI agents solving their problems without goal conflicts in distributed cooperative environments. Finally, we describe a simple scenario to show the effectiveness of the negotiation algorithm implemented in a negotiation meta-language.

• The Journal of Korean Institute for Practical Engineering Education
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• v.4 no.1
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• pp.22-29
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• 2012

Students have to effectively get lots of knowledge and technique for practical education. Usability is one of the most important factors that have to be considered for user-centered design. Students who study design have to recognize the importance of usability and learn the method of problem solving considering usability. For this, the application of project-based and participatory learning for usability education was studied. Study team was organized including graduate, undergraduate, and high school students. Students team identified a research topic, and then studied the topic. Usability evaluation and design improvement was performed in this study. Students could learn usablity evaluation method and design method through the process.

• Journal of the Institute of Electronics and Information Engineers
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• v.49 no.12
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• pp.45-55
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• 2012

The energy efficiency is extremely significant in Wireless Sensor Networks (WSN) which deliver the data sensed in the sensor field, using wireless communications. Under the characteristics of WSN, many MAC protocols employ the Duty Cycle mechanism which continuously operates Wakeup and Sleep periods, for the energy efficiency. However, constant Wakeup period in general Duty Cycle incurs the limited performance of the energy efficiency and the receiving ratio. For addressing this, we design and propose a new scheme called Variable Wakeup Period, considering local traffic conditions. Our scheme enhances receiving ratio by increasing Wakeup period under the high traffic condition, and makes high energy efficiency by decreasing Wakeup period under the otherwise condition. In addition, we evaluate the performance of our scheme by performing the simulation, which experiments the previous synchronous and asynchronous MAC protocols, and which also experiments the same protocols with the proposed scheme, for comparative evaluations.

• Journal of the Microelectronics and Packaging Society
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• v.20 no.4
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• pp.81-85
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• 2013

Wafer stacking technology becomes more important for the next generation IC technology. It requires new process development such as TSV, wafer bonding, and wafer thinning and also needs to resolve wafer warpage, power delivery, and thermo-mechanical reliability for high volume manufacturing. In this study, Cu CMP which is the key process for wafer bonding has been studied using Cu CMP and oxide CMP processes. Wafer samples were fabricated on 8" Si wafer using a damascene process. Cu dishing after Cu CMP and oxide CMP was $180{\AA}$ in average and the total height from wafer surface to bump surface was approximately $2000{\AA}$.

• The Journal of the Korea Contents Association
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• v.8 no.4
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• pp.130-136
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• 2008

With the rapid development of information technologies, various types of game devices have been created. Moreover, the game contents are once created, they can be easily reused on several other devies without depending on their platform or media, which phenomena is so called as one source multi use (OSMU). Especially young gamers are good at not only playing the famous computer games but also good at using and utilizing the brand new and the latest mobile devices, they might be the major consumers in the area of mobile games in the near future. This paper discusses and proposes several points to be considered when a conventional computer game to be transformed into a mobile game. Since the points suggested are very useful when the conventional game is to be ported to the mobile devices of inferior performance, it is expected that more profits could be achieved in the market of mobile game with less investment and effort.

• Journal of IKEEE
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• v.24 no.2
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• pp.543-549
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• 2020

As the importance of security increases in various fields, research on a random number generator (RNG) used for generating an encryption key, has been actively conducted. A high-quality RNG is essential to generate a high-performance encryption key, but the initial pseudo-random number generator (PRNG) has the possibility of predicting the encryption key from the outside even though a large amount of hardware resources are required to generate a sufficiently high-performance random number. Therefore, the demand of high-quality true random number generator (TRNG) generating random number through various noises is increasing. This paper examines and compares the representative TRNG methods based on metastable-based and ring-oscillator-based TRNGs. We compare the methods how the random sources are generated in each TRNG and evaluate its performances using NIST SP 800-22 tests.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.12 no.5
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• pp.243-253
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• 2012

An opinion mining technique which was developed from document classification in area of data mining now becomes a common interest in domestic as well as international industries. The core of opinion mining is to decide precisely whether an opinion document is a positive or negative one. Although many related approaches have been previously proposed, a classification accuracy was not satisfiable enough to applying them in practical applications. A opinion documents written in Korean are not easy to determine a polarity automatically because they often include various and ungrammatical words in expressing subjective opinions. Proposed in this paper is a new approach of classification of opinion documents, which considers only a frequency of word patterns and excludes the grammatical factors as much as possible. In proposed method, we express a document into a bag of words and then apply a learning algorithm using a frequency of word patterns, and finally decide the polarity of the document using a score function. Additionally, we also present the experiment results for evaluating the accuracy of the proposed method.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.12 no.6
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• pp.207-213
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• 2012

With development of IT technology, B2C Social Commerce makes the change from closed type of transaction to the form of an open trading. Also by dramatically reducing the intermediate distribution and removing distribution costs, it provides goods at unbeatable prices to consumers. Depending on the flow of the times, the business-to-business struggles with the difficulty of PRM management and fast promotion of new products. Therefore, it is required B2B Social Commerce, new platform that can collect distribution and consumption firms in one place which is similar to B2C Social Commerce. Unlike the case of B2C social commerce, B2B Social Commerce should have an essential element, Installment payment system to pay over the period without purchase in accordance with the payment paid as a lump sum. B2B Social Commerce model which is introduced in this study will provide the solution of B2B transaction problems, opening up new markets and bring the expansion of the electronic market.