• 항공우주시스템공학회지
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• 제13권1호
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• pp.69-76
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• 2019

본 연구에서 복합재료 구조 설계를 위한 수지 이송 성형 공법의 수지 침투 유동 해석을 수행하였다. 대상 복합재료 구조물은 유체 저장 탱크 구조물이다. 유체 저장 탱크 복합재료 구조물 설계를 위해 자연 섬유 복합재료가 적용되었다. 자연섬유 복합재 구조의 제작을 위해 수지 이송 성형 공법을 채택하였다. 탱크의 적절한 RTM 조건을 도출하기 위하여 수지 침투 유동 해석을 수행하였다. 수지 유동 해석은 상용 유한 요소 해석 시뮬레이션 프로그램을 활용하여 수행하였다. 수지 주입구와 배출구의 다양한 변경에 따른 반복적 해석을 수행하여 최적의 수지 주입 시간과 위치를 결정하였다.

• Nuclear Engineering and Technology
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• 제55권12호
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• pp.4597-4606
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• 2023

Thermal analysis of the CANDU spent fuel dry storage canister is very important to ensure the integrity of the spent fuel. The analyses have been conducted using a conservative approach, with a particular focus on the peak cladding temperature (PCT) of the fuel rods in the canister. In this study, we have performed a realistic thermal analysis using a computational fluid dynamics (CFD) code. The canister contains 9 fuel bundle baskets. A detailed analysis of even a single basket requires significant computational resources. To overcome this challenge, we replaced each basket with an equivalent heat conductor (EHC), of which effective thermal conductivity (ETC) is developed from the results of detailed CFD calculations of a fuel bundle basket. Then, we investigated the effects of some conservative models, ultimately aiming at a realistic analysis. The results revealed: (i) The influence of convective heat transfer in the basket cannot be ignored, but it's less significant than expected. (ii) Modeling of the lifting rod is crucial, as it plays a decisive role in axial heat transfer at the center of the canister and significantly reduces the PCT. (iii) Convection within the canister is very important, as it not only reduces the PCT but also shifts its location upwards.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2002년도 Proceedings of International Symposium on Remote Sensing
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• pp.138-143
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• 2002

This paper describes a framework for extending GIS databases to support moving object data type and query language. The rapid progress of wireless communications, positioning systems, and mobile computing devices have led location-aware applications to be essential components for commercial and industrial systems. Location-aware applications require GIS databases system to represent moving objects and to support querying on the motion properties of objects. For example, fleet management applications may require storage of information about moving vehicles. Also, advanced CRM(Customer Relationship Management) applications may require to store and query the trajectories of mobile phone users. In this trend, maintaining consistent information about the location of continuously moving objects and processing motion-specific queries is challenging problem. We formally define a data model and query language for mobile objects that includes complex evolving spatial structure, and propose core algebra to process the moving object query language. Main profit of proposed moving objects query language and algebra is that proposed model can be constructed on the top of GIS databases.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2006년도 Proceedings of ISRS 2006 PORSEC Volume II
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• pp.725-727
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• 2006

The development of GIS and Location-Based Services requires a high-level database that will be able to allow real-time access to moving objects for spatial and temporal operations. MODB.MM is able to meet these requirements quite adequately, providing operations with the abilities of acquiring, storing, and querying large-scale moving objects. It enables a dynamic and diverse query mechanism, including searches by region, trajectory, and temporal location of a large number of moving objects that may change their locations with time variation. Furthermore, MODB.MM is designed to allow for performance upon main memory and the system supports the migration on out-of-date data from main memory to disk. We define the particular query for truncation of moving objects data and design two migration methods so as to operate the main memory moving objects database system and file-based location storage system with.

• 상하수도학회지
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• 제20권5호
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• pp.701-707
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• 2006

Disinfectant residual should be maintained to achieve biological stability during distribution of treated water. The wide distribution of retention times associated with storage and transport of water in a network and the reactivity of disinfectants make it difficult to maintain adequate residuals at critical locations. Rechlorination at some intermediate locations may reduce the total disinfectant dose while keeping residuals within specified limits throughout the water distribution system. In order to select the adequate location of rechlorination for achieving to maintain of residual chlorine throughout the distribution system, EPANET was used in this study. EPANET was well predicted chlorine transport and residual loss in the distribution system. Location of rechlorination was selected to maintain 0.4mg/L of residual chlorine throughout a water distribution system by field investigation and model simulation. The quantity of chlorine may reduced 36.7% and provided smooth residual between 0.42 and 0.60mg/L, when rechlorination would be used continuously at strategic location within the distribution system.

• 디지털산업정보학회논문지
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• 제17권4호
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• pp.53-62
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• 2021

Deep learning models such as convolutional neural networks and recurrent neual networks process a huge amounts of data, so they require a lot of storage and consume a lot of time and power due to memory access. Recently, research is being conducted to reduce memory usage and access by compressing data using the feature that many of deep learning data are highly sparse and localized. In this paper, we propose a compression-decompression method of storing only the non-zero data and the location information of the non-zero data excluding zero data. In order to make the location information of non-zero data, the matrix data is divided into sections uniformly. And whether there is non-zero data in the corresponding section is indicated. In this case, section division is not executed only once, but repeatedly executed, and location information is stored in each step. Therefore, it can be properly compressed according to the ratio and distribution of zero data. In addition, we propose a hardware structure that enables compression and decompression without complex operations. It was designed and verified with Verilog, and it was confirmed that it can be used in hardware deep learning accelerators.

• 산업경영시스템학회지
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• 제45권4호
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• pp.134-141
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• 2022

Transportation in urban area has been getting hard to fulfill the demand on time. There are various uncertainties and obstacles related with road conditions, traffic congestions, and accidents to interrupt the on-time deliveries. With this situation, the last mile logistics has been a keen issue for researchers and practitioners to find the best strategy of the problem. A way to resolve the problem is to use parcel lockers. Parcel locker is a storage that customers can pick up their products. Transportation vehicles deliver the products to parcel lockers instead of all customer sites. Using the parcel lockers, the total delivery costs can be reduced. However, the inconvenience of customer has to increase. Thus, we have to optimal solution to balance between the total delivery costs and customers' inconvenience. This paper formulates a mathematical model to find the optimal solution for the vehicle routing problem and the location problem of parcel lockers. Experimental results provide the viability to find optimal strategy for the routing problem as well as the location problem.

• 한국방재학회 논문집
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• 제10권3호
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• pp.109-118
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• 2010

본 연구에서는 소규모 저류시설의 유출저감효과를 NRCS 유출곡선지수의 감소율로 정량화하였다. 저류시설로 유입되는 유출용적을 계산하기 위해 수정합리식을 이용하였다. 다양한 강우 특성(강우 빈도, 지속시간)과 저류시설의 규모에 따라 설치 전후의 NRCS 유출곡선지수 감소율을 정량화하였다. 마지막으로 저류시설의 규모에 따른 유출곡선지수의 감소율을 나타내는 도표를 개발하였다. 이 도표는 저류시설의 최적 위치 및 용량 결정을 할 경우 저류시설의 효율을 평가하는데 합리적이고 효율적으로 활용될 수 있을 것으로 기대된다. 본 연구에서 제안된 방법에 의한 결과는 또한 기존 연구와의 비교를 통해 검증하였다.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2015년도 학술발표회
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• pp.244-244
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• 2015

Managed Aquifer Recharge (MAR) in the form of Aquifer Storage and Recovery (ASR) systems are being applied for numerous water augmentation projects both in developed and developing countries. Given the onset of Climate Change and its influence on weather patterns and land use, it has been acknowledged the utilization of this technology will be ever increasing. This technique like all others does have its drawbacks or disadvantages, whereby to overcome these drawbacks or disadvantages it is recommended that logical planning process be followed. In this study, we developed a decision framework known as "Decision framework for the planning, designing, construction/testing and implementation of subsurface water storage system" to further standardize the planning and design process of subsurface water storage system to increase the probability of having a successful ASR/ASTR project. The formulation of this framework was based on earlier frameworks, guidelines, published papers and technical reports which were compiled into a data collection database. The database of which consider both qualitative and quantitative aspect for example recharge objectives, site location, water chemistry of the native, source and recovered water, aquifer characteristics(hydraulic conductivity, transmissivity, porosity), injection/pumping rate, ecological constraints, societal restrictions, regulatory restrictions etc. The assimilation of these factors into a singular framework will benefit the broad spectrum of stakeholder as it maps the chronological order under which ASR project should be undertaken highlighting at each stage the feasibility of the project. The final stage of which should result in fully operational ASR system. The framework was applied to two case studies and through the application of a modified ASR site selection suitability index (Brown et al., 2005) a score was derived to identify the performance of each site. A high score of which meant a maximize chance of success given the reduce presence of project constraints.

• 한국공간정보시스템학회 논문지
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• 제10권3호
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• pp.79-91
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• 2008

최근 이동체의 위치 데이타를 활용한 위치 기반 서비스에 대한 관심이 높아지면서 보다 효율적인 이동체 위치 데이타 관리 시스템으로 클러스터 기반 분산 컴퓨팅 구조인 GALIS(Gracefully Aging Location Information System)가 제시되었다. 그러나, GALIS의 서브 시스템인 SLDS(Short-term Location Data Subsystem)에서 SDP Master는 다수의 SDP(Short-term Data Processor) 노드들이 처리한 질의 결과를 취합하여 Client로 보내는 구조이기 때문에 SDP Master에 장애가 발생하거나 부하가 집중될 경우에 서비스가 중지되거나 Client로의 응답 시간이 길어지는 문제가 있다. 따라서, 본 논문에서는 기존 SLDS에 이중화를 지원하기 위해 SDP Master를 추가하여 기존 SLDS의 안정성과 가용성을 높이고 이동체 위치 데이타의 질의 처리 성능을 향상시킨 확장 SLDS를 설계 및 구현하였다. 확장 SLDS에서는 이중화된 두 대의 SDP Master를 가동하여 한 SDP Master에 장애가 발생하더라도 다른 SDP Master가 서비스를 계속 제공함으로써 현재 위치 데이타의 실시간성과 시스템의 안정성을 보장한다. 또한, 확장 SLDS는 두 대의 SDP Master가 질의 처리를 분산하여 수행하기 때문에 Client로의 응답 시간을 줄일 수 있다. 마지막으로 확장 SLDS의 장애 테스트와 질의 처리 성능을 실험하였으며, 이러한 실험을 통해 확장 SLDS의 고신뢰성 및 고가용성을 검증하였다.