• The KIPS Transactions:PartC
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• v.17C no.1
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• pp.37-46
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• 2010

In an IPTV system, the rights of the content and service provider can be protected by using Conditional Access System (CAS) and Digital Right Management (DRM). In case of the CAS, only the authorized user who has structured authentication keys can decrypt the encrypted content. However, since the CAS establishes a secure channel only between content provider and Smart Card (SC), it cannot protect the system against McCormac Hack attack which eavesdrops on unsecure channel between SC and Set-Top Box (STB) and SC cloning attack. In this paper, we propose a robust multi-STB assisted SC / STB authentication protocol which can protect the IPTV system against not only McCormac Hack attack, but also SC cloning attack. The previous works which bind a STB and a SC during the SC registration phase against the SC cloning attack does not support multi-STB environments. The proposed system which dynamically updates the STB information in subscriber management system using the bi-directional channel characteristic of IPTV system can support the user's multi-STB device effectively.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.6C
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• pp.520-528
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• 2008

At present Content Management Systems (CMS) with various and diverse web contents have been in wide applications. But, for CMS of each enterprise has its own metadata which is very different from others, it causes the serious problem of web contents repetition. Also, it's a difficult technology to support protecting copyright of web contents which are in separated CMSs. Therefore, in this paper, we solved the problem of contents repetition through metadata integration between mutually heterogeneous CMSs. We also propose the technology of web contents authentication code for avoiding contents repetition and applying digital rights protection by supporting safe ship in vast quantity of contents.

• Proceedings of the Korea Water Resources Association Conference
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• 2009.05a
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• pp.149-153
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• 2009

Physics-based distributed rainfall-runoff models are now commonly used in a variety of hydrologic applications such as to estimate flooding, water pollutant transport, sedimentation yield and so on. Moreover, it is not surprising that GIS has become an integral part of hydrologic research since this technology offers abundant information about spatial heterogeneity for both model parameters and input data that control hydrological processes. This study presents the development of a distributed rainfall-runoff prediction system for the Guem river basin ($9,835km^2$) using an Object-oriented Hydrological Modeling System (OHyMoS). We developed three types of element modules: Slope Runoff Module (SRM), Channel Routing Module (CRM), and Dam Reservoir Module (DRM) and then incorporated them systemically into a catchment modeling system under the OHyMoS. The study basin delineated by the 250m DEM (resampled from SRTM90) was divided into 14 midsize catchments and 80 sub-catchments where correspond to the WAMIS digital map. Each sub-catchment was represented by rectangular slope and channel components; water flows among these components were simulated by both SRM and CRM. In addition, outflows of two multi-purpose dams: Yongdam and Daechung dams were calculated by DRM reflecting decision makers' opinions. Therefore, the Guem river basin rainfall-runoff modeling system can provide not only each sub-catchment outflow but also dam inand outflow at one hour (or less) time step such that users can obtain comprehensive hydrological information readily for the effective and efficient flood control during a flood season.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2008.02a
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• pp.73-75
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• 2008

1984년 Shamir에 의해 ID 기반의 암호시스템에 대한 개념이 소개된 이후로 많은 연구가 이루어져 왔다. ID 기반의 암호시스템에서는 복호화 할 수 있는 자를 암호화 하는 자가 선택하여 암호화 하기 때문에 정당한 복호화 권한을 가지고 있는 자만이 복호화를 할 수 있다. 이러한 복호화 권한은 어플리케이션에 따라 양도할 수 있어야 한다. 예를 들어 네트워크 스토리지의 경우는 정당한 권한을 가진 자에게 암호화 되어 저장되어 있는 컨텐츠를 복호화 할 수 있도록 권한을 양도해 주어야 한다. 대리 재 암호화(Proxy Re-encryption)은 복호화 권한을 다른 사람에게 양도할 수 있는 기법에 관한 것이다. 재 암호화 기법은 DRM과 같은 방송 통신 환경에 적합하게 사용될 수 있다. 본 논문에서는 ID 기반에서 복호화 권한을 적법하게 양도할 수 있는 재 암호화 기법을 제안한다.

• 한국노년학
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• v.38 no.4
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• pp.1083-1105
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• 2018

The present study sought to capture day-to-day fluctuation of the daily happiness among Korean urban older adults and to examine whether the within person fluctuation of daily happiness is explained by the social and physical activities the older adults experience each day. We also examined whether the within person association between daily social, physical activities and the daily happiness varies by individual characteristics(i.e. gender, age, educational level and health). In addition, we explored the relationships between the level and fluctuation of daily happiness and the level of global happiness. The data was collected by multi-method approach, which includes general survey, daily diary method and collection of physical activity data through the activity monitors. In total, 175 urban older adults participated for seven days of daily diary survey. The data about the number of steps and the time spent on sedentary activities, light intensity physical activities and moderate to vigorous intensity physical activities were also collected during the same period from 16 sub-samples using activity monitors. Hierarchical linear modeling was applied for the analysis. The results were as below. First, the level of happiness of older adults fluctuated during a week, and the patterns of fluctuation varied by the gender and the health. Second, socializing with their children and friends elevated their levels of happiness. Also the impact of contacts with siblings on the level of daily happiness was greater for the unhealthy group compare to the healthy group. Third, older adults were happier on the days when they walked more, but the level of daily happiness decreased on the days when they spent longer time for low intensity physical activities. Lastly, the higher level of daily happiness were related to the higher level of global happiness, but the degree of fluctuation of daily happiness was not related to the level of global happiness. The implications of these results and suggestions for future research are discussed.