• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.2
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• pp.371-378
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• 2014

As people are taking part in more versatile social activities, it becomes more frequent and more important for people to share personal information each other in appropriate level. Unfortunately, although the rapid spread of smart devices and advance of network technologies have brought many applications for information sharing into our hands, they do not provide effective mechanism for sharing personal information on collocated people. In this paper, we introduce an android application named WhoAmI which provides the functionality of sharing personal information on nearby users over Wi-Fi Direct as well as Wi-Fi network environment. According to the predefined access level such as business, community or friend, WhoAmI naturally provides profile information to accessible users. In addition, the information such as music, photo, movie can be effectively shared through the application.

• Korean Journal of Materials Research
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• v.30 no.5
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• pp.267-271
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• 2020

Cerium oxide (ceria, CeO₂) is one of the most wide-spread oxide supporting materials for the precious metal nanoparticle class of heterogeneous catalysts. Because ceria can store and release oxygen ions, it is an essential catalytic component for various oxidation reactions such as CO oxidation (2CO + O₂ 2CO₂). Moreover, reduced ceria is known to be reactive for water activation, which is a critical step for activation of water-gas shift reaction (CO + H₂O → H₂ + CO₂). Here, we apply van der Waals-corrected density functional theory (DFT) calculations combined with U correction to study the mechanism of water chemisorption on CeO₂(111) surfaces. A stoichiometric CeO₂(111) and a defected CeO₂(111) surface showed different water adsorption chemistry, suggesting that defected CeO₂ surfaces with oxygen vacancies are responsible for water binding and activation. An appropriate level of water-ceria chemisorption energy is deduced by vdW-corrected non-local correlation coupled with the optB86b exchange functional, whereas the conventional PBE functional describes weaker water-ceria interactions, which are insufficient to stabilize (chemisorb) water on the ceria surfaces.

• Journal of Environmental Impact Assessment
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• v.17 no.5
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• pp.271-278
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• 2008

The purpose of this research provides the basic solution about waterfront and promotes the inherent capability, that recoveries both the river and gives the river for water quality to improve plan. In this study, we compare and analysis the slope contact between filter media of the porous concrete and planting concrete. As a result, when appling the porous concrete, it can show the removal efficiency is SS 53%, BOD 39%, COD 20%, T-N 36% T-P 42% and appling planting concrete is SS 58%, BOD42%, COD 26%, T-N 45%, T-P 53%. Therefore, planting concrete is higher removal efficiency (SS 5%, BOD 3%, COD 6%, T-N 9%, T-P 10%) than porous concrete. The experimental results show that using purification filter media on planting concrete is better than on porous concrete, because it have the higher purification filter efficiency. The quality of water improves vegetarian concrete, that can expect the increase of the self-purification capacity and improve the spectacle for providing the waterside and planting of planting concrete. In addition, it can complete and apply the research if having enough time for experimentation and accurate study for mechanism by plant, we can use both planting concrete filter media and the existing dike. As a result, we can gain the better quality of the water of the city's rivers and good economic value, that is spread by all cities applicable technologies. So it can be expected using well for future.

• Journal of Digital Convergence
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• v.15 no.10
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• pp.429-436
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• 2017

A design thinking-based collaborative workshop in which various stakeholders in the milk processing industry circulation ecosystem participated shows a new problem innovation paradigm that encourages the spread of practical prototyping culture. in the expression of empathy and collective intelligence among members on facing issues, the conversion of collaboration and communication methods, the business handling of the organization based on the design work method as 'creativity mechanism'. In this workshop, which was promoted in three stages of 'approach to problems', 're-definition of problems', and 'experience-based future vision design', participants themselves redefine real problems in terms of the accuracy of feed orders between feed suppliers and livestock farmers, ordering of feeds on time, cost reduction of feed supply and present new alternatives and expanded business areas. The results suggested in this workshop suggest the usefulness of design thinking in business innovation in that they presented how to approach the problem and a creative thinking system to find its solution to direct and indirect stakeholders of the industry as well as the improvement of supply and demand rate of livestock feed and quality.

• Journal of Korean Tunnelling and Underground Space Association
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• v.5 no.4
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• pp.349-360
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• 2003

A practical modeling approach has been proposed in this study to better understand the behavior of penetration grouting which is normally applied to the jointed rock masses to increase the bearing capacity and to reduce the ground water flow into the tunnel. Based on Bingham model together with a steady-state flow of the grout, penetration model is simulated in the commercial package called UDEC and, injection pressure as well as joint thickness are found to be the main parameters to determine the range of grout spread. Another numerical model on fracturing grouting is also suggested and, in this case, the tensile strength as well as cohesion of the rock masses are proven to be the major factors to decide the fracturing mechanism of the rock masses. The reinforcement effect of the grout-reinforced rock masses is calculated from the suggested algorithm on orthotropic material model and it is found that the directional stiffness of reinforced rock masses is increased up to 3 to 4 times compared with original jointed rock masses. Future work will be concentrated on the water control around the tunnel by the grout injection and a model test will also be performed to verify the suggested methods developed in this study.

• The Journal of the Korea Contents Association
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• v.15 no.2
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• pp.40-57
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• 2015

IoT is the foundation technology that the things share the information through connected with Internet to provide service based on these information. It is applied to various fields such as personal, public and industry. Therefore, the service development is required to meet the requirement of the various service environments. The IoT service environment will be developed as the participation IoT service environment which increase the value and efficiency such as the Broadcasting and web services changed from the service provider environment to the user participation service. The user can directly reflect their requirements using the user participation IoT service environment. So, the types of IoT services will diverse and accelerate the spread of IoT service. In this paper, we derive the IoT service element through the analysis of various service scenarios, and propose the participation IoT service model and modeling mechanism. It provides the sequential service model and the relation based service model according to the service modeling proficiency of user. The proposed environment provides the web-based user interface that is implemented by the participation IoT service brokering platform.

• Journal of Internet Computing and Services
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• v.11 no.5
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• pp.71-80
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• 2010

The purpose of this research is to help IPTV (Internet Protocol Television) commercialization using newly produced educational contents in the area of entertainment and education which currently popular in the market. It is called, Stimulus $Tester^{TM}$, endow reaction time from the feedback of learning system, using a non-direct method, for example, a remote controller. Reaction time is the learning efficiency promotion mechanism that learner ascertain the learning condition of oneself by the time with solved questions from the solving the question in given time. Reaction time also play a key role that the learner may go through course which distribute the point to PC from Server. If this system is ready, we expect that the educational industry will gradually spread out. To verify the learning efficiency of this system, we concluded that the learning improvements, by an Internet-based and a paper-based test, of the increase by 51%, from 2.47min to 1.27min, during reaction of 7 days.

• Korea Trade Review
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• v.41 no.5
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• pp.113-138
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• 2016

This study analyzed the impact when Korea expands Chinese Renminbi(RMB) as invoicing currency on the trade to China using Monte-Carlo simulation. Primarily, we analyzed the impact on the balance of Korean Won(KRW) converted from RMB in a case that simulated exchange rate(Korean won to Chinese Renminbi) and realized historically identical probability distribution but in different stochastic process. In addition, we developed the simulation of the case where the volatility of RMB to KRW exchange rate abnormally expanded. The major results found in this study are as follows. First, in the case where RMB exchange rate simulated in identical probability distribution but in the different stochastic process, no matter how much RMB was utilized as invoicing currency, expansion of the RMB exchange rate and exchange rate volatility operated as positive mechanism to increase the KRW converted balance. Secondly, while the expansion of US dollar exchange rate volatility positively influences the balance on average, it caused a polarization of balance, which makes under-average-balance lower and over-average-balance higher. On the contrary, the expansion of RMB exchange rate volatility even shows a similar mechanism but the impact is more moderate than USD exchange rate volatility. Thirdly, as RMB exchange rate volatility expanded, the balance of translated invoicing currency (RMB) declined, whilst the negative impact of RMB exchange rate volatility on balance of translated invoicing currency(RMB) showed diminishing effect. Lastly, the influence of RMB's exchange rate volatility through RMB usage ratio trends similar to bull spread strategy, which is a combination of call option with put option. Therefore, since RMB usage in invoicing currency could spawn a hedging effect, corporations might utilize RMB as a strategic device for maximizing profits.

• Journal of Internet Computing and Services
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• v.9 no.6
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• pp.37-48
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• 2008

VoIP service is a transmission of voice data using SIP protocol on IP based network, The SIP protocol has many advantages such as providing IP based voice communication and multimedia service with cheap communication cost and so on. Therefore the SIP protocol spread out very quickly. But, SIP protocol exposes new forms of vulnerabilities on malicious attacks such as Message Flooding attack and protocol parsing attack. And it also suffers threats from many existing vulnerabilities like on IP based protocol. In this paper, we propose a new Virtual Proxy Server system in front of the existed Proxy Server for anomaly detection of SIP attack and stateful management of SIP session with enhanced security. Based on stateful virtual proxy server, out solution shows promising SIP Message Flooding attack verification and detection performance with minimized latency on SIP packet transmission.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.19 no.1
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• pp.25-32
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• 2009

The glass-ceramics composed of coal bottom ash produced from a thermal power plant, $Na_{2}O$ and $Li_{2}O$ as a flux agent and $TiO_2$ as a nucleation agent were fabricated and its microstructures were analyzed. The nepheline was a major crystal phase in the glass-ceramics fabricated and its amount increased with $TiO_2$ addition. The glass-ceramics without $TiO_2$ addition had the thick surface crystals induced by a surface-crystallization mechanism and no crystal in the interior matrix. The surface crystallization, however, was restrained and the interior matrix was completely crystallized showing dendrite shape spread with fine particles < $1{\mu}m$ when added with $TiO_2$ above 4 wt%. For the glass-ceramics containing 6 wt% $TiO_2$, the $5{\mu}m$-long dendrite crystal; were interlocked each other which could suppress the crack propagation effectively at the external loading applied.