• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.45 no.1
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• pp.63-70
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• 2017

In this paper, we design and fabricate a de-orbiter using drag-sail and evaluate deployment characteristics. Without employing an actuator to deploy, the de-orbiter is activated by the SMA wire based the release mechanism and driven by the restoring force of the tape-spring. For efficient storage and deployment of drag-sail, an origami method of original ISO flasher is chosen and low priced mylar film is used as the material of the drag-sail. In addition, through the fault tree analysis method which is one of the one-shot device reliability evaluation methods, we confirm the reliability of the de-orbiter(0.997572) and the Roller failure has the highest criticality. Finally, we find feasibility of the proposed de-orbiter through the deployment demonstration of drag-sail.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.33 no.5
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• pp.385-396
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• 2015

The purpose of this study are in selecting a core service and drawing an analysis functions and service sector, based on contents of geo-spatial big data. For the study, the demand survey in the methodology has to be done by reviewing of preceding geo-spatial big data service. The survey has conducted by targeting on those experts in Industry-Academy-Research cooperation. From the survey, we could draw out requirements for the analysis function and the geo-spatial big data service sector. Also, order of priorities in service of four fields(Society, Environment, Economy, Humanities) has been utilized by a QFD(Quality Function Deployment). With the data, the first two priorities and required sectors for each field were selected for the analysis functions. From the result, we could suggest the core service model(plan), and also expect developments following each sectoral core service in the future.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.7
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• pp.1515-1521
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• 2013

AIS is a core service in the maritime safety domain. AIS Message type #6 and #8(for binary date) can be used for carrying any kind of MSI(Maritime Safety Information). The MSC(Maritime Safety Committee) approved SN/Circ. 289 on Guidance on the use of AIS Application-Specific Messages in 2010. The MSI that carried by AIS-ASM can support to reduce the maritime accidents. Since a new AIS-ASM service places an additional load on the VDL(VHF Data Link), there should be a deployment process for new AIS-ASM services. In this paper we analyze the AIS-ASM services and survey the extended functions and systems for each AIS-ASM service. We also present the survey of the statistical analysis of local AIS messages. and suggest preliminary research topics for the deployment of new AIS-ASM services. VDL monitoring system, system for detection and removal of malfunctioning AIS equipments, and value analysis process of the MSI services are required.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.6
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• pp.2889-2909
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• 2017

Wireless sensor networks (WSNs) have attracted lots of attention in recent years due to their potential for various applications. In this paper, we seek how to efficiently deploy relay nodes into traditional static WSNs with constrained locations, aiming to satisfy specific requirements of the industry, such as average energy consumption and average network reliability. This constrained relay node deployment problem (CRNDP) is known as NP-hard optimization problem in the literature. We consider addressing this multi-objective (MO) optimization problem with an improved Artificial Bee Colony (ABC) algorithm with a linear local search (MOABCLLS), which is an extension of an improved ABC and applies two strategies of MO optimization. In order to verify the effectiveness of the MOABCLLS, two versions of MO ABC, two additional standard genetic algorithms, NSGA-II and SPEA2, and two different MO trajectory algorithms are included for comparison. We employ these metaheuristics on a test data set obtained from the literature. For an in-depth analysis of the behavior of the MOABCLLS compared to traditional methodologies, a statistical procedure is utilized to analyze the results. After studying the results, it is concluded that constrained relay node deployment using the MOABCLLS outperforms the performance of the other algorithms, based on two MO quality metrics: hypervolume and coverage of two sets.

• The Journal of the Acoustical Society of Korea
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• v.41 no.4
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• pp.419-425
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• 2022

This paper aims to evaluate the acoustic detection performance for the deployment of the source and receiver positions of a bi-static sonar. In contrast with a mono-static sonar, a bi-static sonar has a large amount of computation and complexity for deployment. Therefore, in this study, we propose an assessment method that reduces the amount of computation while considering the variability of the ocean environment as a method to apply to the placement of the source and receiver of a bi-static sonar. First, we assume the representative ocean environment in the shallow and deep water. The signal excess is calculated with the source to receiver ranges and sensor depths. And the result is compared with the proposed assessment method of acoustic detection performance.

• The Journal of the Acoustical Society of Korea
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• v.43 no.4
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• pp.437-444
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• 2024

Bistatic sonar performance varies significantly depending on the ocean environment, the location (latitude, longitude) and water depth of the source and receiver. Therefore, research on optimal deployment of bistatic sonar considering ocean environment is necessary. In this study, we suggest an algorithm to optimize the location and water depth of source and receiver when operating monostatic and bistatic sonar on two spatially separated surface ships in the Ulleung Basin in the East Sea. A particle swarm optimization algorithm was used to search the location and water depth of the source and receiver to maximize the detectable area within the search area. As a result of performing bistatic sonar deployment using the algorithm proposed in this study, the detectable area increased as the number of model iterations increased. Additionally, it was confirmed that the source and receiver on the two surface ships converged to the optimal location and water depth.

• Proceedings of the KSME Conference
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• 2001.06c
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• pp.333-338
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• 2001

Fault tree is a widely used methodology for analyzing product reliability. The fault trees are usually constructed using the experiences of expert reliability engineers in top-down approaches and have different structures according to each expert's subjectivity. In this work it is tried to find a general method for the fault tree construction based on the function tree that is the result of product function deployment. Based on the function tree, the method has the advantage of resulting an objective fault tree since the faults are defined as the opposite concept of functions. The fault tree construction of this work consists of the following steps: 1) definition of product primary function with the viewpoints of product operation and configuration, 2) construction of functional relation chart using a grouping algorithm, 3) abstraction of functional block diagram according to operation sequences and configuration of a product, 4) construction of function tree for each viewpoint, and 5) construction of fault tree by matching the function tree and simplification of the result.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.36 no.9
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• pp.851-858
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• 2008

In this paper, the wrinkling behavior of vertically creased corner-loaded square membranes was studied using geometrically nonlinear post-buckling analysis. The membranes were modeled using shell elements, and the meshes were seeded with semi-random geometrical imperfection to instigate the buckling deformation. A pristine and creased membranes with various initial deployment angles were considered in the analyses and the results were compared. Results showed that local wrinkles initiated near the corner where the higher load was applied, which grew to form a single diagonal global wrinkle as the load ratio increased. It was also found that the local wrinkle initiation and the global wrinkle formation were significantly dependent on the initial deployment angles.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2006.11a
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• pp.315-318
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• 2006

This paper concerns about coupled dynamic analysis of the deep-seabed mining system in launching operation. The dynamic behavior of mining system consisting of lifting pipe, buffer station, flexible conduit and self-propelled miner is simulated in time domain. The launching operation is divided into four critical phases: (1) deployment of miner and flexible conduit, (2) deployment of lifting pipe, flexible conduit and miner, (3) touch-down of miner, (4) final launching. The dynamic responses of sub-systems - miner, flexible conduit, buffer and lifting pipe - are analyzed in each launching phase. According to the changing periods of forced excitation at the top, the dynamic responses of sub-systems are diverse in their characteristics. It has been shown that the total integrated responses of sub-systems are strongly affected by the design parameters. Especially, the principal dimensions of flexible conduit seem to be significant in determining of the global response. Based on the simulation results, safe operation conditions are investigated.

• Journal of the Korea Institute of Military Science and Technology
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• v.13 no.3
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• pp.421-430
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• 2010

This work describes a derivation process of JIC(Joint Integrating Concept) based JFC(Joint Functional Concept) analysis of an Aegis BMD(Ballistic Missile Defense). JIC is developed through JOC(Joint Operating Concept) and JFC based on capstone strategy and concept. Aegis BMD is a sea-based ballistic missile defense to detect ballistic missile threat, increase engagement battlespace and enable multiple engagement based on Aegis ships. Aegis BMD is a good case of JIC due to performing an Joint operations based on System of Systems under highly complicated NCW environment. This work analyses JFC using QFD(Quality Function Deployment) and UJTL(Universal Joint Task List). From this analysis the JIC of Aegis Korean BMD is derived using a CASE tool.