• Proceedings of the Korea Concrete Institute Conference
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• 2006.11a
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• pp.873-876
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• 2006

At the green roof on the concrete structure, root penetration can be the most problem to water leakage. Root occur cracks due to penetrate to concrete which have porous organization by itself. Crack on the concrete structure would be constantly shrinks and expands, it occur to water leakage and decrease durability of concrete structure. Therefore, in this paper, the result of the root penetration test for waterproofing which protect concrete structure from the water leakage or other environment conditions would be apply to understand the reason of root penetration.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2004.05a
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• pp.85-90
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• 2004

We divided the planting bale into waterproof layer, drainage layer and soil layer so at to investigate changes of live load according to species of wood and composition of the base to make rooftops green. The results are follows, 1. As concerning construction and live load for green roof, sheet waterproofing is superior. 2. When materials of drainage are changed crushed gravel into artificial lightweight graval or ferrite, live load of planting bale is decreased about 22% and 25% in order. 3. When ingredients of soil are chased normal sand into volcanic sand, live load of base is decreased about 28%. Especially, when it is changed into ferrite, 54% of live load is decreased. 4. In this study, all live load we concerned excesses the standard about roof live load of office, school and house. Hence, structure has to be concerned thoroughly when making rooftops green. But, we judge that various methods for making rooftops green can be applied if we consider roof garden when we plan new buildings.

• Ecology and Resilient Infrastructure
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• v.3 no.2
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• pp.117-125
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• 2016

Current cities encounter various types of water problems due to rapid urbanization and climate change. The increasing significance of urban water problems calls for the establishment of resilient alternatives to prevent and minimize social loss that results from these phenomena. As a background research for establishing resilient infrastructures for the mitigation of urban water problems, we evaluated the robustness of structural alternatives for urban flood as a representative case. Combining the robustness index (RI) and the cost index (CI), we suggested the robustness-cost index (RCI) as an indicator of the robustness of structural alternatives, and applied the index to assess the existing infrastructures and structural alternatives (i.e., sewer network expansion, additional storage tank construction, and green roof construction) at a site prone to floods located around Gangnam-station, Seoul, Korea. At a rainfall intensity frequency range of 2 to 20 years, the usage of a storage tank and a green roof showed relatively high RCI value, with a variation of an alternative showing greater RCI between the two depending on the size of design rainfall. For a rainfall intensity frequency of 30 years, installing a storage tank with some green roofing was the most resilient alternative based on the RCI value. We proposed strategies for establishing resilient infrastructures for the mitigation of urban floods by evaluating the robustness of existing infrastructures and selecting optimal structural alternatives with the consideration of scales of design disaster.

• Journal of Broadcast Engineering
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• v.15 no.2
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• pp.192-204
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• 2010

As illegal distribution of the terrestial DTV broadcast program occurs very frequently in on-line, the needs to protect broadcast program have increased. In this paper, a new approach to implement a system for terrestial DTV broadcast program protection based on program protection information(PPI) is proposed. In our approach, the broadcast program is recorded with encryption according to redistribution condition of the PPI and packaged into a file with key information and PPI together. And we also define a set of domain protocol for supporting user fair-use of broadcast program. In the proposed system, copy control can also be provided by process of home domain management. Implementation results show that our system can protect broadcast programs with efficiency and can support conditional distribution within home domain in order to satisfy user fair-use.

• The KIPS Transactions:PartC
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• v.9C no.1
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• pp.9-16
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• 2002

As existing analog video surveillance systems could save and retrieve data only in a limited space within short distance, it had many constraints in developing into various application systems. However, on the back of development of the Internet and computer technologies, digital video surveillance systems can be controlled from a remote location by web browser without space limits. Moreover, data compression and management technologies with Index Search algorithm make it possible to efficiently handling, storing, and retrieving a large amount of data and further motion detection algorithm enhances a recording speed and efficiency for a practical application, that is, a practical remote recordable video surveillance system using our efficient algorithms as mentioned, called WebCam. The WebCam server system can intelligently record and save video images digitized through efficient database management, monitor and control cameras in a remote place through user authentication, and search logs.

• Journal of Convergence for Information Technology
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• v.10 no.8
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• pp.144-151
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• 2020

User-authentication process is necessary in Fintech Service. Especially, authentication on smartphones are carried out through PIN which is inputted through virtual keypads on touch screen. Attacker can analogize password by watching touched letter and position over the shoulder or using high definition cameras. To prevent password spill, various research of virtual keypad techniques are ongoing. It is hard to design secure keypad which assures safety by fluctuative keypad and enhance convenience at once. Also, to reconfirm user whether password is wrongly pressed, the inputted information is shown on screen. This makes the password easily exposed through high definition cameras or Google Class during recording. This research analyzed QWERTY based secure keypad's merits and demerits. And through these features, creating Tetris shaped keypad and piece them together on Android environment, and showing inputted words as Tetris shape to users through smart-screen is suggested for the ways to prevent password spill by recording.

• Smart Media Journal
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• v.13 no.1
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• pp.52-59
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• 2024

This paper proposes a plan to improve the reception radio environment of the mobile terminal and maintain a constant reception electric field by using small cells in a small closed environment. In order to configure an efficient communication infrastructure for small cells, both ends of wireless transmission and reception of an Ethernet-based wireless video recording system are connected using an L2 switch. The small cell connected to the receiving side L2 switch shares the wireless network section of the wireless video recording system and connects to the transmitting side L2 switch. After that, when it is normally linked to FMS, a management system for small cells, through the Internet network, the output of small cells is checked. In order to verify the results, a proposed network is formed on the elevator inside the building with a poor radio wave environment, and the radio wave environment is measured before and after the small cell application in the section where the elevator operates. As a result, the main parameters of the radio wave environment in all sections of the elevator are improved, as well as a constant receiving electric field strength within the moving elevator.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 1998.11a
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• pp.520-524
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• 1998

인터넷상에서 실시간 영상회의 시스템을 구축하기 위해 MBone망을 구성하고 RTP에 의해 영상 및 음성정보의 고속전송이 가능하게 하였다. 이를 기반으로 멀티미디어 영상회의 프로토콜인 H.323을 탑재하여 다자간 회의 시스템을 구현하고, 더불어 영상사서함 기능을 부가하여 녹화, 재생이 가능하게 한다. 구현결과 기존의 시스템보다 속도가 향상됨을 확인했다.

• KIEAE Journal
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• v.16 no.1
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• pp.73-79
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• 2016

This study aimed to investigate the flood prevention effect expected from the afforestation of a large area metal roof of an industrial complex located in an area prone to floods in the rainwater outflow reduction aspect through computer simulation based on soil, which is a key element of the system. In order to conduct a more realistic simulation, the properties of the surveyed soil were generated through substantive analysis, soil texture analysis, and saxton method. A comparative performance evaluation was conducted by using soil depth and ponding depth, which are key elements of the system, as variables. The study result showed that during the heavy rainfall period, the bottom ash artificial soil had 61% rainwater outflow reduction effect, which was 11% higher than the SWMM standard sand.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.13 no.4
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• pp.821-827
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• 2009

Currently, with the development of web 2.0 knowledge sharing system became more and more important. In this paper, we proposed and implemented seminar assistant system using database system and knowledge sharing system on public seminar. We recorded speaker's voice and presentation files on our system and user can review past talks on our seminar review systems. Our database system is implemented using MS SQL, and Input/Output Completion Port(IOCP) socket model as our server side network module. Also we used presentation software using Direct Show with MFC and Windows Presentation Foundation(WPF). and our review system is based on WFP programmed with C# language.