• KIPS Transactions on Computer and Communication Systems
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• v.5 no.7
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• pp.159-172
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• 2016

This paper presents a novel algorithm for searching evacuation paths in indoor disaster environments. The proposed method significantly improves the time complexity to find the paths to the evacuation exit by introducing a light-weight Disaster Evacuation Graph (DEG) for a building in terms of the size of the graph. With the DEG, the method also considers load balancing and bottleneck capacity of the paths to the evacuation exit simultaneously. The behavior of the algorithm consists of two phases: horizontal tiering (HT) and vertical tiering (VT). The HT phase finds a possible optimal path from anywhere of a specific floor to the evacuation stairs of the floor. Thus, after finishing the HT phases of all floors in parallel the VT phase begins to integrate all results from the previous HT phases to determine a evacuation path from anywhere of a floor to the safety zone of the building that could be the entrance or the roof of the building. It should be noted that the path produced by the algorithm. And, in order to define the range of graph to process, tiering scheme is used. In order to test the performance of the method, computing times and evacuation times are compared to the existing path searching algorithms. The result shows the proposed method is better than the existing algorithms in terms of the computing time and evacuation time. It is useful in a large-scale building to find the evacuation routes for evacuees quickly.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.11
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• pp.5301-5323
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• 2017

Small cell deployment offers a low-cost solution for the boosted traffic demand in heterogeneous cellular networks (HCNs). Besides improved spatial spectrum efficiency and energy efficiency, future HCNs are also featured with the trend of network architecture convergence and feasibility for flexible mobile applications. To achieve these goals, dual connectivity (DC) is playing a more and more important role to support control/user-plane splitting, which enables maintaining fixed control channel connections for reliability. In this paper, we develop a tractable framework for the downlink SINR analysis of DC assisted HCN. Based on stochastic geometry model, the data-control joint coverage probabilities under multi-frequency and single-frequency tiering are derived, which involve quick integrals and admit simple closed-forms in special cases. Monte Carlo simulations confirm the accuracy of the expressions. It is observed that the increase in mobility robustness of DC is at the price of control channel SINR degradation. This degradation severely worsens the joint coverage performance under single-frequency tiering, proving multi-frequency tiering a more feasible networking scheme to utilize the advantage of DC effectively. Moreover, the joint coverage probability can be maximized by adjusting the density ratio of small cell and macro cell eNBs under multi-frequency tiering, though changing cell association bias has little impact on the level of the maximal coverage performance.

• YAKHAK HOEJI
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• v.59 no.6
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• pp.278-283
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• 2015

The computerized prospective Drug Utilization Review (DUR) program supported by the Korean government has provided alerts to physicians and pharmacists since December 2010. This study aims to propose and apply the tiering system in "drug combinations to avoid (DCA)" and "age-precaution" alerts based on severity to improve the compliance of users. To propose the severity and clinical importance of 647 DCA alerts and 140 age precautions, a Delphi evaluation survey was conducted. An expert panel comprising 5 clinical pharmacists and 5 physicians were participated in mail surveys. Based on the results of Delphi survey, DCA pairs were classified into 3 groups; group 1 (70.6%), 2 (26.9%), and 3 (2.8%). Drug-age precaution ingredients were also classified into three groups; group 1 (53.6%), group 2 (40.7%), and group 3 (5.7%). When this grouping was applied to claim data from 2011 to 2013, the majority of alerts had occurred in the groups of high severity. Presenting DUR alerts with severity level is expected to improve the compliance of clinicians. The implementation of tiering system in DUR criteria should be considered.

• Journal of Environmental Impact Assessment
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• v.20 no.3
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• pp.269-279
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• 2011

Sustainability assessments tend to integrate ecological, social, and economic concerns. Sustainability assessment could be considered the highest rung in the assessment ladder. Broad strategies that seek to integrate individual SEA(Strategic Environmental Assessment) could be subjected to a sustainability assessment. Sustainability assessment could incorporate global and transboundary effects and priorities into SEA and project-level EIA(Environmental Impact Assessment). SEA could provide an environmental context and direction for project-level EIA. Procedural and substantive EIA requirements can be addressed through tiering such as sustainability assessment, SEA, project-level EIA. In Korea, PERS(Prior Environmental Review System) that has been utilized to evaluate administrative plans related with various kinds of development projects should be evolved not only to incorporate environmental impacts into early stage decision-making, but also to implicate sustainability assessments that include social equity and economic efficiency. Integration of SEA and sustainability assessment can be initiated through the application of DPSIR (Driving Force - Pressure - State - Impact - Response ) framework that was developed by European Environmental Agency.

• Journal of Internet of Things and Convergence
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• v.9 no.1
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• pp.19-24
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• 2023

Recently, with the recent rapid development of memory technology, various types of memory are developed and are used to improve processing speed in data management systems. In particular, NAND flash memory is used as a main media for storing data in memory-based storage devices because it has a nonvolatile characteristic that it can maintain data even at the power off state. However, since the recently studied memory-based storage device consists of various types of memory such as MRAM and PRAM as well as NAND flash memory, research on memory management technology is needed to improve data processing performance and efficiency of media in a storage system composed of different types of memories. In this paper, we propose a memory mapping scheme thought technique for efficiently managing data in the storage device composed of various memories for data management. The proposed idea is a method of managing different memories using a single mapping table. This method can unify the address scheme of data and reduce the search cost of data stored in different memories for data tiering.

• Journal of Digital Convergence
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• v.10 no.8
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• pp.159-172
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• 2012

In the recent, due to explosion of Digital Universe, the performance of computer and storage system is reducing. Therefore, the upgrade and capacity expansion needs is growing. Countermeasure for this problem is required fundamental and long-term solutions rather than piecemeal expansion. In this paper, we establish a data management policy for an enterprise through the operational status of storage system and the analysis of data value of it, and implement ILM-based tiered storage system on the basis of these. The results of this study shows the overall throughput was improved about 21% compared to the existing system, it is very effective to maintain continuous quality and reduce operating costs in the long term aspect.

• International journal of advanced smart convergence
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• v.10 no.1
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• pp.62-74
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• 2021

We compare Over-the-Tops (OTTs), Netflix and Amazon Prime Video (APV) with five success factors of innovation. Firstly, Netflix offers better personalized service than APV, because APV has collaborative filtering algorithms to recommend safe bets, not the customers really want. Secondly, APV' user interface is undercooked to lock the members in, even if it has more content and better price offer than Netflix retaining its loyal customers despite the price increase. Thirdly, Netflix has simple subscription model with three tiering, but APV has complicated pricing model having annual and monthly, APV and Prime Video (AV) app, Amazon subscription and extra payment of Amazon Prime Channels (APCs). Fourthly, Amazon has fewer partnership than Netflix especially when it comes to local TV series. Instead, Amazon has live TV channel collaboration including sports content. Lastly, both have strategic and operational agility in their organization well.

• Proceedings of the Korea Information Processing Society Conference
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• 2023.11a
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• pp.50-52
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• 2023

ML/DL과 같은 AI의 연구가 HPC 환경에서 수행되면서 데이터 병렬화, 분산 학습 및 대규모 데이터 세트를 처리를 위한 요구사항이 급격히 증가하였다. 또한, 병렬처리 연산에 특화된 가속기 기반 이기종 아키텍처 환경 변화로 I/O 처리에 고대역폭, 저지연의 스토리지 기술을 필요로 하고 있다. 본 논문에서는 고집적의 병렬 컴퓨팅 환경에 고성능 HPC, AI 애플리케이션을 처리하기 위한 티어링 스토리지 기술을 논한다. 나아가 실제 고성능 NVMe 기반의 플래시 티어링 계층 구성에서 액세스 패턴에 따른 데이터 처리 환경을 구축하고 성능을 검증한다. 이로써 다양한 사용자 어플리케이션의 I/O 패턴을 특성에 맞게 지원할 수 있다.

• Journal of KIISE
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• v.42 no.6
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• pp.691-698
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• 2015

Application launch time is an important performance metric to user experience in desktop and laptop environment, which mostly depends on the performance of secondary storage. Application launch times can be reduced by utilizing solid-state drive (SSD) instead of hard disk drive (HDD). However, considering a cost-performance trade-off, utilizing SSDs as caches for slow HDDs is a practicable alternative in reducing the application launch times. We propose a new SSD caching scheme which migrates data blocks from HDDs to SSDs. Our scheme operates entirely in the file system level and does not require an extra layer for mapping SSD-cached data that is essential in most other schemes. In particular, our scheme does not incur mapping overheads that cause significant burdens on the main memory, CPU, and SSD space for mapping table. Experimental results conducted with 8 popular applications demonstrate our scheme yields 56% of performance gain in application launch, when data blocks along with metadata are migrated.

• Korean journal of communication and information
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• v.49
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• pp.39-56
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• 2010

This study on the exposed the viewers diversity as a basic cable television service. Diversity is the most basic goal of broadcasting policy has important implications. But still, such as cable and pay-media research on the viewing diversity has made a limited basis. SO much to offer for the cable offers viewers receive the number of channels available to compare the diversity of the field was verified. Price rises of analysis for the cable the more the number of channels offered to supply the channel has increased the diversity of the field. SO granted in accordance with the results of a market strategy, but for a variety of channels to be provided by a policy perspective, the price depending on the choice of a variety of audiences can be quite limited means. That is a wide range of viewers watching the channel had a right to be limited. These phenomena to improve the pay television service and the need to manage the Product channel diversity index was raised.