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군 USN 환경에서 효율적인 데이터 저장 및 질의 처리 방법 연구
권영모,최현식,정연돈,Kwon, Young-Mo,Choi, Hyun-Sik,Chung, Yon-Dohn 한국군사과학기술학회 2010 한국군사과학기술학회지 Vol.13 No.5
Recently, the role of Ubiquitous Sensor Network(USN) has been considered to be essential for supporting the near future Network Centric Warfare(NCW) and Tactical Information Communication Network(TICN). In this paper, we explore a set of data storage methods(external storage, local storage and data storage) and query processing methods in WSN. In particular, we focus on analyzing a novel data structure for supporting the local storage method, named the partial ordered tree(POT). The main idea behind POT is that sensor readings are usually correlated with the physical spatial domain. With the help of POT, only a small portion of sensor nodes participate in query processing tasks, and thus network lifetime is greatly increased. Through a series of simulation experiments, we demonstrate that the POT based local storage method clearly outperforms the existing data storage methods in terms of the energy-efficiency, which directly affects the network lifetime, for processing exact match queries, range queries and top-k queries.
ESS(Energy Storage System) 열관리를 위한 액침 냉각 활용에 대한 수치해석 연구
함정균,조홍현,신명재,유나영 한국 지열 · 수열에너지학회 2024 한국지열에너지학회논문집 Vol.20 No.2
The introduction of the sector coupling concept has expanded the scope of ESS utilization, resulting in the importance of thermal management of ESS. To ensure the safe use of the lithium-ion batteries that are used in ESS, it is important to use the batteries at the optimal temperature. To examine the utilization of liquid cooling in ESS, numerical study was conducted on the thermal characteristics of 21700 battery modules (16S2P array) during liquid cooling using Novec-649 as insulating fluid. The NTGK model, an MSMD model in ANSYS fluent, was used to investigate thermal characteristics on the battery modules with liquid immersion cooling. The results show that the final temperature of the battery module discharged at 5 C-rate is 68.9o C using natural convection and 48.3o C using liquid cooling. However, the temperature difference among cells in the battery module was up to 0.5o C when using natural convection cooling and 5.8o C when using liquid cooling, respectively, indicating that the temperature difference among cells was significantly increased when liquid cooling was used. As the mass flow rate increased from 0.01 kg/s to 0.05 kg/s, the average temperature of the battery module decreased from 48.3o C to 38.4o C, confirming that increasing the mass flow rate of the insulating fluid improves the performance of liquid immersion cooling. Although partial liquid immersion cooling has a high cooling performance compared to natural convection cooling, the temperature difference between modules was up to 8.9o C, indicating that the thermal stress of the battery cells increased.