• Journal of the Korea Institute of Military Science and Technology
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• v.9 no.3
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• pp.20-24
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• 2006

In this paper, our research efforts and activities for displaying flight simulation graphics on multi-monitors connected to a Linux cluster is introduced. In this pilot system graphics rendering as well as view calculation including LOD implementation for each monitor is peformed on each sub-node computer connected to the monitor rather than using an expensive main server. The Linux cluster is constructed by combining general-purpose desktop computers, and MPI library Is used for communication between sub-nodes. It could be concluded from our experience that it is possible to construct a massive multi-monitor display system by adding to the cluster as many sub-node computers and monitors as possible with economic efficiency.

• Journal of Information Technology Applications and Management
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• v.26 no.1
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• pp.53-64
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• 2019

The purpose of this study is to find out the fast delivery route that several drones return a truck again after departing from it for delivery locations at each cluster while the truck goes through the cluster composed of several delivery locations. The main issue is to reduce the total delivery time composed of the delivery time by relatively slow trucks via clusters and the sum of maximum delivery times by relatively fast drones in each cluster. To solve this problem, we use a three-step heuristic approach. First, we cluster the nearby delivery locations with minimal number of clusters satisfying a constraint of drone flight distance to set delivery paths for drones in each cluster. Second, we set an optimal delivery route for a truck through centers of the clusters using the TSP model. Finally, we find out the moved centers of clusters while maintaining the delivery paths for the truck and drones and satisfying the constraint of drone flight. distance in the two-dimensional region to reduce the total delivery time. In order to analyze the effect of this study model according to the change of the number of delivery locations, we developed a R-based simulation prototype and compared the relative efficiency, and performed paired t-test between TSP model and the cluster-based models. This study showed its excellence through this experimentation.

• Bulletin of the Korean Chemical Society
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• v.23 no.2
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• pp.309-314
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• 2002

The ablation dynamics and cluster formation of $C_n^+$ ions ejected from 355 nm laser ablation of a graphite target in vacuum are investigated using a reflectron time-of-flight (RTOF) mass spectrometer. At low laser fluence, odd-numbered cluster ions with $3{\leq}n{\leq}15$ are predominantly produced. Increasing the laser fluence shifts the maximum size distribution towards small cluster ions, implying the fragmentation of larger clusters within the hot plume. The temporal evolution of $C_n^+$ ions was measured by varying the delay time of the ion extraction pulse with respect to the laser irradiation, providing significant information on the characteristics of the ablated plume. Above a laser fluence of $0.2J/cm^2$ , large cluster ions ($n{\geq}30$) are produced at relatively long delay times, indicating that atoms or small carbon clusters aggregate during plume propagation. The dependence of the intensity of ablated $C_n^+$ ions on delay time after laser irradiation shows that the most probable velocity of each cluster ion decreases with cluster size.

• 한국전산유체공학회:학술대회논문집
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• 2006.05a
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• pp.121-125
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• 2006

CFD has been used in aircraft development and broaden its influence in various fields of industries. This paper briefly introduces the historical trends of computing system, the overview of CFD applications in Korean Supersonic Trainer Development Program and the demand for CFD software in industry points of view.

• The Journal of the Korea Contents Association
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• v.12 no.7
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• pp.425-436
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• 2012

This research aims to investigate the life-style and types of leisure experienced among airline flight attendants during temporary stays abroad. In this study 2 hypotheses based on literature reviews were employed. Questionnaires were also developed based on data collected from previous studies. Subjects of the study were focused on flight attendants in Legacy Airlines. Factor analysis and reliability coefficients were used to examine the internal consistency among variables. Seven dimensions of leisure, which are cultural experience, pursuit of success, social orientation, humanity, pursuit of fashion, shopping preferences and health-orientation were identified from factor analysis. Three dimensions of leisure, which include type of rest, type of sports, and activity of tourists, were identified from factor analysis accordingly. Lifestyle factors were extracted from a result of cluster analysis, cluster 1- Passive lifestyle, Active lifestyle community type 2, and Cluster 3 analyzed Self-satisfied lifestyle types. Airline cabin crew workers involved in the life style analysis can make good use of leisure time.

• International Journal of Naval Architecture and Ocean Engineering
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• v.8 no.6
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• pp.563-576
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• 2016

The flight deck of an aircraft carrier is relatively vulnerable compared to its hull, as the damage of some subsystems on the flight deck may cause the carrier losing its operational capability. Therefore, this work aims to represent a simulative method for evaluating the resistance of the flight deck's operational capability in the condition that the aircraft carrier is together with its strike group and the enemy uses the anti-ship missiles with the cluster warheads to attack. In the simulations, the susceptibility of the carrier and the vulnerability of the aircraft guarantee resources are gained. Then, with the help of the closed queuing network, the residual sortie generation rate can be solved, which reflects the flight deck's residual operational capability. The results have proven that the flight deck is of strong resistance to these attacks while it is very sensitive to the loss of some key aircraft guarantee resources.

• Proceedings of the Korean Society of Computer Information Conference
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• 2020.01a
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• pp.3-4
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• 2020

공연을 위한 드론 군집비행의 제어시스템에 관한 기존의 연구 결과들은 실시간으로 반응하지 않으며, 비숙련자가 제어하기 어렵다는 문제점이 있다. 본 논문에서는 첫 번째로 HCI를 기반으로 한 웨어러블 형태의 장갑 컨트롤러를 사용한다. 두 번째로 각각의 음 정보에 실시간으로 반응하도록 FFT를 사용한 주파수 정보를 컴퓨터로 수신 받는다. 세 번째로 각각의 군집비행 움직임 정보를 복수의 드론에게 송신하는 새로운 방법의 드론 실시간 군집비행 제어시스템을 설계하였다.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.32 no.5
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• pp.891-898
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• 2022

Along with global interest, drones are expanding the base of utilization such as transportation of goods, forest protection, and safety management, and cluster flights are being applied in various fields such as military operations and environmental monitoring. Currently, specialized networks such as e-UM 5G for services in specific industries are being established in Korea. In this regard, drone systems are also moving to establish specialized networks to provide services that are fused with AI and autonomous flight. As drones converge with various services, various security threats in various environments are also subordinated, and in response, requirements and guidelines for drone security are being prepared in Korea. In this paper, we propose a technology method for peer identification and safe information provision between cluster flight drones by utilizing a cryptographic module equipped with wireless LAN and quantum entropy-based random number generator in a cluster flight system and a mobile communication network such as e-UM 5G.

• Bulletin of the Korean Chemical Society
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• v.16 no.3
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• pp.238-243
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• 1995

A pulsed molecular beam source having short pulse duration (typically 70 ${\mu}s)$ and narrow velocity distribution (${\Delta}$v/v=8% for helium) has been costructed utilizing a commercial fuel injector. Beam characteristics of helium and ammonia seeded in helium expansions are accomplished by the use of an electron impact time-or-flight mass spectrometer. The comparisons between experimental data and theoretical calculations show that the proper beam speed is important to predict the evolution of stream temperature and valve shutter function. The decreasing tendency of pulse duration with increasing cluster size leads to the conclusion that the cluster beam property is described as a function of cluster mass and disinct cluster temperature.

• Journal of the Korea Society for Simulation
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• v.28 no.3
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• pp.83-89
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• 2019

This research describes quantitative effects of initial dispersion conditions upon the dispersion randomness of Magnus rotor bomblets. Ratios of the missile spin rate to the missile velocity, a, flight path angles, ${\gamma}$ and altitudes, h, were changed to investigate their effects on dispersion randomness. Dispersion was analyzed through calculation of 6 degree of freedom motion equation with aerodynamic coefficients from wind tunnel experiments. In order to analyze the randomness, regression analysis is adopted to calculate the coefficient of determination. The optimized ratio of the missile spin rate to the missile velocity and flight path angle were obtained and the dispersion altitudes had more effect on the dispersion diameter and had less effect on dispersion than other parameters.