• Tunnel and Underground Space
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• v.20 no.2
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• pp.112-118
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• 2010

Before blasts that can have direct impacts on human bodies or structures, it is necessary to assess impacts of ground vibration. Therefore, frequency has been recognized as an important factor in order to assess impact on ground vibration and damages. There have been many studies on impacts of frequency. But, there have been no studies on relations between vibration and frequency according to delay time difference. In this study, we examined the relations between delay time difference and frequency according to each frequency with which reinforcement and destructive intervention repeat through delay time difference obtained using superposition modeling of single hole blasting waveform based on the theory of time difference developed by Langefors.

• Journal of Advanced Navigation Technology
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• v.24 no.6
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• pp.508-514
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• 2020

Geofence defines the area that UAS should not enter or exit to ensure the safety of their operations, and is considered as one of critical capabilities of the UTM (UAS traffic management) system. In this study, a geofence simplification method using modified perpendicular algorithm is proposed. The performances of the proposed geofence simplification method were evaluated with actual building data, and the evaluation results confirmed that the number of vertices can be effectively reduced while minimizing the spatial size of the geofence.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38A no.5
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• pp.401-408
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• 2013

Dual-layer differential codebook using 8-PSK (phase shift keying) constellation as its codeword elements, is proposed for Long term evolution (LTE) and/or LTE-Advanced systems. Due to the temporal correlation of the adjacent channel matrices, the consecutive precoding matrices are likely to be similar. This approach quantize only the differential information of the channel instead of the whole channel subspace, which virtually increase the codebook size to realize more accurate quantization of the channel. Especially, the proposed codebook has the same properties of LTE release-8 codebook that is, constant modulus, complexity reduction, and nested property. The mobile station can be designed by using less expensive non-linear amplifier utilizing constant modulus property. Computer simulations show that the capacity of the proposed dual-layer codebook performs almost 1.2dB better than those of any other non-differential codebooks with the same amount of feedback information.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.12
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• pp.5207-5215
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• 2010

Selecting proper location for complex facility with special purpose need comprehensive consideration on the condition and surrounding environment. Especially, in case of living space for human, lighting, ventilation, efficiency in land use, etc. are important elements. Diverse 3D analysis through 3D topography modeling and virtual simulation is necessary for this. Now, it can be processed with relatively inexpensive cost since high resolution satellite image essential in topography modeling is provided with domestic technology through Arirang No. 2 satellite (KOMPSAT2). In this study, several candidate sites is selected for complex planning with special purpose and analysis on proper location was performed using the 3D topography modeling and land information. For this, land analysis, land price calculation, slope analysis and aspect analysis have been carried out. As a result of arranging the evaluation index for each candidate site and attempting the quantitative evaluation, proper location could be selected efficiently and reasonably.

• The Journal of the Korea Contents Association
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• v.13 no.6
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• pp.9-19
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• 2013

In this paper, we develop a Spatio-Temporal graph as of a key component of our knowledge representation Scheme. We design an integrated representation scheme to depict not only present and past but future in parallel with the spaces in an effective and intuitive manner. An event in general occupies not only a space but a time. Hence a crucial premise for the simulation of virtual situations is to position events in the multi-dimensional context, that is, 3-D space extended by the temporal dimension. Furthermore an event tends to have physical, social and mental aspects intertwined. As a result we need diverse information structures and functions to model entities and relations associated with events and to describe situations in different stances or perspectives of the virtual agents. These structures and functions are implemented in terms of integrated and intuitive representation schemes at different levels such as Ontology View, Instance View, ST View, Reality View. The resulting multi-dimensional comprehensive knowledge structure accommodates multi-layered virtual world developing in the time to maximize the diversity of situations in the historical context. The viability of this knowledge representation scheme is demonstrated with a typical scenario applied to a simulator implemented based on the ST Graph. The virtual stage based on the ST graph can be used to provide natural contexts for situated learning or next-generation simulation games.

• Journal of Korea Multimedia Society
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• v.7 no.3
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• pp.388-398
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• 2004

This paper focuses on the reduction method of message traffic occurred when multiple participants collaborate in the distributed virtual environment. It is referred to as filtering method of update message to minimize data traffic exchanged in the virtual environment, and it is the essential process to improve the scalability of the virtual environment. Spatial partitioning method, a popular filtering technique, divides the whole environment into smaller sub-parts in order to make it small the regions to be maintained consistently. However, it is less flexible and adaptable because the information of area of interest must be configured before simulation. In this paper, the concept of dynamic area of interest is proposed, which is highly adaptable by applying dynamic environmental elements to AOI management. It uses multiple layering and multiple consistency algorithms for dynamic management, and makes it possible to consume system resource efficiently. For performance evaluation, experiments are performed with virtual avatars, measuring message traffic. Finally, the proposed model could be applied to the AOI management systems which accommodate massive users like MMORPG, or virtual communities.

• 한국HCI학회:학술대회논문집
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• 2006.02b
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• pp.57-62
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• 2006

건축디자인 초기단계에서 다이어그램은 아이디어 및 디자인 해결방안을 도출하기 위한 분석 도구로써 중요한 의미를 지닌다(Wang, 1999; Do, 1997). 이러한 다이어그램은 시각적 디자인 피드백을 가능하게 함으로써 건축디자인 실무 및 교육에서 필수적인 디자인 도구라고 할 수 있다 (Schon and Wiggins, 1992; Gross, 1996; Kurmann, 1998). 최근에 IT 기술이 건축분야에 적용됨에 따라, 건축가들의 전통적으로 고려되어 왔던 인간의 행동, 자연현상, 건축재료, 건축부재, 대지조건 외에 다양한 IT 기술과 관련된 정보를 분석하고 고려할 필요성을 가지게 되었다. 그러나 이러한 다양한 IT 기술은 건축적인 요소들과 접목되어 적용되기 때문에 건축가들은 디자인 초기단계부터 IT 기술의 접목이 가능한 디자인 도구를 필요로 하게 되었다. 즉, 이는 IT 정보와 공간정보와의 관계 및 적용을 건축가가 빠르게 이해하고 분석하고 이를 디자인에 반영할 수 있도록 도와주는 시각적 다이어그램 표출이 가능한 디자인 도구가 필요하게 되었다. 본 논문에서는 다양한 IT 기술과 공간 정보의 다양한 형태의 관계를 나타내는 3 차원 버블 다이어그램을 이용한 계략 디자인 방법을 제안하고, 이를 기반으로 3 차원 버블 다이어그램을 지원하면서 건축 디자인 초기단계에 이용 가능한 디자인 도구를 개발한다. 본 연구에서 개발된 디자인 도구는 정보의 유형에 따라 다양하게 형태를 변화시킬 수 있는 노드(node)와 연결선(edge)로 구성되고, 저장된 특정 건축정보는 다이어그램으로 생성된 디자인 대안을 평가하는데 사용된다. 일종의 DSS(Decision Support System)인 본 시스템은 디자인 초기단계에서 3 차원 디자인 아이디어를 제공할 뿐만 아니라 다양한 디자인 대안을 빠르게 생성하고 이를 실시간으로 평가함으로써 디자인 효율성을 증가시킬 것이다. 본 시스템은 유비쿼터스 기술이 적용된 신도시에 생성될 통관관제센터 디자인에 실험적으로 적용되었다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.8C
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• pp.777-785
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• 2006

H.264 is the prominent video coding standard in various applications such as real-time video streaming and digital multimedia broadcasting, since it provides enhanced compression performance, error resilience tools, and network adaptation. Since compressed video stream is vulnerable to packet loss, error resilience and error concealment(EC) tools are essential for the transmission of video over the Internet. In this paper, we first propose a simple temporal EC method that improves the EC performance for intra-frame in H.264 when the amount of motion is relatively small. Then we propose a new hybrid EC method for intra-frame in H.264, which combines the spatial EC and temporal EC adaptively. The simulations are performed in packet-lossy environments, and the proposed hybrid EC method shows about 0.5-4dB PSNR improvement compared to the conventional spatial EC method that is used for intra-frame in H.264.

• Journal of Korean Association for Spatial Structures
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• v.5 no.2 s.16
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• pp.73-79
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• 2005

Tensegrity is a relatively new structural system based on the use of continuous tension-discontinuous compression. Of course, a much more detailed structural investigation would be necessary, but at least in order to achieve the intended purpose, it is essential to understand the structural principles and the fundamental forces of tensegrity. Once this point is established, the applications of them to architecture are described, as well as the characteristics of these structures. Then, in spite of the controversial definitions to explain these systems, several examples of tensegrity prototypes or modules constructed in iESD(Institute of Environmental Structure Design) are presented to illustrate the feasibility of tensegrity as a lightweight structure. In this work, consequently, the reformability and application of tensegrity modules have also been researched in architecture, after the patterns of basic module as well as fundamental definition are introduced.

• Journal of Korean Society for Geospatial Information Science
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• v.20 no.4
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• pp.19-27
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• 2012

RUSLE(Revised Universal Soil Loss Equation) has been widely used to estimate the soil loss amount of watersheds from rainfall erosivity, soil erodibility, topographic features and cropping management condition. Rainfall erosivity is the most dominant and sensitive factor among these so that the determination of reliable rainfall erosivity is essential to estimate the soil loss of watershed. Since there has been no criterion to determine the rainfall erosivity in Korea, the empirical values, determined from the relation between the annual average rainfall and erosivity or suggested by TBR(Transport Research Board), have been used for designing the erosion control structure and controlling the soil erosion for watersheds. In this study, the procedure for estimating the rainfall erosivity using frequency analysis is proposed. The most fitted distribution function, with calculated rainfall erosivities with various frequencies and durations, has been also selected. The suggested procedure can be used to estimate the optimal value of rainfall erosivity for RUSLE in order to design soil erosion structures and control the soil erosion in watersheds effectively.