• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2012.05a
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• pp.35-41
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• 2012

Performance of a liquid rocket thrust chamber with regenerative cooling scheme has been numerically analyzed using in-house CFD code which can predict combustion/cooling performance and provide nozzle design parameters. This paper investigates trade-offs between combustion and cooling performance with varying amount of fuel directly injected into the chamber wall to form cooling films. Also is analyzed the effect of varying mixture ratios for the peripheral injectors on combustion performance enhancement. Further efforts to verify/improve the simulation methodology including comparison with the firing test results are planned to make it a reliable tool to optimize the film cooling and other major design parameters.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2015.11a
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• pp.76-77
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• 2015

In construction industry, management of construction factors such as cost, schedule, quality and safety is the most important key for delivering successful projects. According to the Smart Market Report, a magazine specialized in construction industry, recently said 'Off-site Prefabrication' is a significant trend related with construction productivity in global construction industry. It is a kind of practice shift from On-site to Off-site. A lot of general contractors in oversea have been using 'Multi-trade MEP Ceiling Rack Prefabrication' method for getting benefits such as decreased cost & schedule and increased labor productivity. Thus, in this paper, critical management factors at each phase from design to installation was derived by researching case studies. Forwardly, it can be a basic guideline for applying Multi-trade MEP Ceiling Rack Prefabrication in Korea construction industry.

• Speech Sciences
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• v.8 no.4
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• pp.157-168
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• 2001

The limited capacity model has been used to explain linguistic interactions and trade-offs that occur in children's speech. The purpose of the present investigation is to explore the interrelationship of MLU (as an index of syntactic development) and fluency in the spontaneous speech of normal children. Twenty normal children's (ten girls and ten boys, aged 36-48 months) spontaneous speech samples were obtained during free-play interactions with their mothers or other adults. The results indicated that the MLU of disfluent utterances were significantly longer than that of fluent utterances. Also, disfluencies occurred more frequently in longer utterances than in shorter utterances. In addition, the utterances where disfluencies occurred more than 2 times were longer than those where disfluencies occurred once. These results imply that the increase of MLU appear to affect not only the occurrence of disfluent utterances, but also the number of disfluencies within the utterances. In other' words, these findings show that there are trade-off effects between MLU and fluency. This is discussed within a limited capacity framework.

• Journal of Construction Engineering and Project Management
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• v.4 no.4
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• pp.33-40
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• 2014

Maximizing the profitability and minimizing the duration of construction projects in extreme weather regions is a challenging objective that is essential for project success. An optimization model is presented herein for the time-profit trade-off analysis of construction projects under extreme weather conditions. The model generates optimal/near optimal schedules that maximize profit and minimize the duration of construction projects in extreme weather regions. The computations in the model are organized into: (1) a scheduling module that develops practical schedules for construction projects, (2) a profit module that computes project costs (direct, indirect, and total) and project profit, and (3) a multi-objective module that determines optimal/near optimal trade-offs between project duration and profit. One example is used to show the impact of extreme weather on construction time and profit. Another example is used to show the model's ability to generate optimal trade-offs between the time and profit of construction projects under extreme weather conditions.

• ETRI Journal
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• v.31 no.5
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• pp.481-488
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• 2009

This paper proposes a new multiuser scheduling algorithm that can simultaneously support a variety of different quality-of-service (QoS) user groups while satisfying fairness among users in the same QoS group in MIMO broadcast channels. Toward this goal, the proposed algorithm consists of two parts: a QoS-aware fair (QF) scheduling within a QoS group and an antenna trade-off scheme between different QoS groups. The proposed QF scheduling algorithm finds a user set from a certain QoS group which can satisfy the fairness among users in terms of throughput or delay. The antenna trade-off scheme can minimize the QoS violations of a higher priority user group by trading off the number of transmit antennas allocated to different QoS groups. Numerical results demonstrate that the proposed QF scheduling method satisfies different types of fairness among users and can adjust the degree of fairness among them. The antenna trade-off scheme combined with QF scheduling can improve the probability of QoS-guaranteed transmission when supporting different QoS groups.

• Proceedings of the IEEK Conference
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• 2001.09a
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• pp.81-84
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• 2001

We propose a novel noise littering method based on adaptive windowing. To restore a noisy signal adaptive filtering methods have been widely researched and used. However, conventional adaptive filtering methods have a trade-off between noise suppression and edge preservation since they adopt fixed size filters. In this paper applying the adaptive windowing concept to adaptive filtering, we overcome the trade-off, The filter size is adaptively selected depending on signal statistics. The visual results of the signal and image restorations convincingly show the superior preservation of edge and detail and suppression of noise for the proposed adaptive windowed adaptive filter compared with conventional methods.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2011.05a
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• pp.754-756
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• 2011

Most of the sources of security and privacy issues in RFID technology arise from the violation of the air interface between a tag and its reader. This paper will approach the security risk analysis is process from the perspective of the RFID tag life cycle, identify the tag usage processes, identify the associated vulnerability and threat to the confidentiality, integrity and availability of the information assets and its implications for privacy, and then mitigate the risks.

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 2004.11a
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• pp.372-372
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• 2004

• Korea Trade Review
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• v.44 no.1
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• pp.269-283
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• 2019

Due to environmental issues such as global warming, the importance of renewable energy is growing. Solar Power System is one of the most growing eco-friendly energy industries in the world, but Korea's solar energy industry faces fierce competition due to the trade regulations and changes in energy related laws in the major markets such as the U.S., EU and China. Therefore, Korea needs to diversify its export markets towards emerging markets. This paper analyzed 162 countries in the world and developed a model to measure how promising the countries are. GSMI(Grid connected Solar Market Index) and OSMI(Off-grid Solar Market Index) are invented based on the models. By using the developed model and the data of 162 countries over the 15-year period from 2000 to 2014, the foreign markets are ranked for searching the export market. According to the analysis, China, Japan, U.S, India and Taiwan ranked first to fifth in GSMI and OSMI ranking, which were followed by China, India, Bangladesh, Philippines and Afghanistan. The model developed through this research is expected to provide a more reasonable and scientific approach to the advancement of the Korean solar energy industry into overseas markets.

• THE INTERNATIONAL COMMERCE & LAW REVIEW
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• v.20
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• pp.423-440
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• 2003

The trial business of e-trade service providers for supporting small enterprises to find their markets abroad is about to begin from the end of March, 2003. The department of Industrial Resources held the "Committee of e-trade service provider selection" with professors of e-trade field, and selected three companies: ECplaza, EC21 and Tpage Global. The e-trade service providers combine the various technologies of on-line trades and off-line trades to support small enterprises with lack of marketing skills by intermediation of overseas buyers and production, registration of e-catalogs and offers, administration of inquiries, trade negotiations, and contract settlement. Prospective small enterprises with exports under US$ 5 million will be selected by 2005. The selected companies will be supported fully by the government, and will be provided with the services by the e-trade service providers. e-Trade service will be the most potential and successful ones in the future, which helps traders and organizations preparing for globalization.