• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.50 no.12
• /
• pp.857-866
• /
• 2022

Fixed-wing UAVs have long endurance and range capabilities compared to other aerial platforms. These advantages led fixed-wing UAVs to become a popular platform for reconnaissance missions in the military. In this research, we modeled fixed-wing UAVs, including the landing gear model and developed a guidance and control system for flight control computers to construct a HILS environment. We also developed an autopilot system that includes automated take-off, cruise, and landing control for UAVs. We also retrived the Aerodynamic coefficients an UAV using Datcom and AVL software and used them for 6 degrees of freedom modeling. The Flight control computer calculates guidance commands using the Carrot chasing guidance law after distinguishing the condition of the UAV based on 16 pre-defined flight modes and calculates control inputs using Nonlinear Dynamic Inversion (NDI) control scheme. We used RTNngine to integrate the Simulink model and flight control computer for HILS environment formulation.

• Journal of the Korea Society for Simulation
• /
• v.19 no.4
• /
• pp.189-198
• /
• 2010

Conceptual Model of the Mission Spaces(CMMS) is a first abstraction model of the military real world and serves as a knowledge(mission spaces) reference models for development, interoperability and reusability of defense modeling and simulation(M&S) systems, by capturing basic information about entities involved in any mission and their key actions and interactions. Therefore, the completeness of CMMS is the key to success for the quality of M&S systems based on it. To improve quality and credibility of CMMS, the Verification, Validation and Accreditation(VV&A) processes of CMMS is very important. This paper briefly describes the K-CMMS(Korean Conceptual Model of Mission Space) and the VV&A process.

• Journal of the Korea Society for Simulation
• /
• v.18 no.4
• /
• pp.21-28
• /
• 2009

In the past, most of battle occurred in flatland and simple military force size gave a big influence in combat result. However, after the World War I, most of battles took place at the various terrain features such as forest, downtown, jungle and many others. Therefore, terrain factor exerts big influence on battle with weapon system in the ground warfare. However, effect of terrain has been explained only by quantitative manner in the battle. Furthermore, combat simulation and modeling applied a method that lower the combat capability of battle factors. In this paper, we present instrumentation that evaluate impact of terrain using fractal dimension. We determine the fractal dimension value by the "box counting dDimension" and density to calculate impact of terrain. Furthermore, we analyzed correlation with fractal dimension and density for battle result that obtained from the EINSTein model which is an agent-based simulation. We compare with 'Stalingrad battle' result out of battle example and analyzed. This study presented a method combat effectiveness that effect of terrain calculate quantitatively using fractal dimension.

• Journal of the Korea Institute of Building Construction
• /
• v.15 no.6
• /
• pp.621-629
• /
• 2015

Construction worker safety and safety training continue to be main issues in the construction industry. In order to promote safety awareness among workers, it is imperative to develop a more effective and efficient safety training. This study compared two methods in construction worker safety training: 1) a conventional lecture and 2) 3D simulation through Building Information Modeling. Both training methods included the same contents, a selection of safety standard and guide suggested by Occupational Safety and Health Agency and the Korea Occupational Safety and Health Agency; the contents were then produced into two types of training methods. A survey was conducted targeting on safety managers, in which the managers evaluated lifelikeness, active learning and enjoyment that each of training methods can promote. The results of the survey showed that innovative method using 3D simulation was more effective than conventional lecture method in terms of its lifelikeness, active learning and enjoyment. This study will provide implications that innovative method using the virtual reality is more effective than conventional lecture method.

• Journal of Soil and Groundwater Environment
• /
• v.14 no.6
• /
• pp.1-18
• /
• 2009

A series of three-dimensional numerical simulations using a generalized multidimensional hydrodynamic dispersion numerical model is performed to simulate effectively and to evaluate quantitatively impacts of urbanization on density-dependent groundwater flow and salt transport in a coastal aquifer system, Suyeong-Gu, Busan, Korea. A series of steady-state numerical simulations of groundwater flow and salt transport before urbanization with material properties of geologic formations, which are established by numerical modeling calibrations considering all the urbanization factors, is performed first without considering all the urbanization factors. A series of transient-state numerical simulations of groundwater flow and salt transport after urbanization is then performed considering the urbanization factors individually and all together. Finally, the results of both numerical simulations are compared with each other and analyzed. The results of the numerical simulations show that density-dependent groundwater flow, salt transport, and seawater intrusion in the coastal aquifer system are intensively and extensively impacted by the urbanization factors. Especially, these urbanization factors result in the changes of the total groundwater volume and salt mass in the coastal aquifer system. However, such impacts of each urbanization factor are not spatially uniform but locally different.

• Journal of the Institute of Convergence Signal Processing
• /
• v.19 no.3
• /
• pp.139-146
• /
• 2018

Underwater acoustic communication can be applied to various area such as scientific, commercial and military survey using Autonomous Underwater Vehicles and Unmanned Underwater Vehicles. Underwater communication is studying very actively by advanced country like United States. But differ from wireless communication in the air, underwater acoustic communication has some difficult problems, ISI(Inter Symbol Interference) due to multipath and limit of transmission bandwidth due to slow propagation of sound wave. In this paper, SC-FDE and OFDM transmission system for the cancellation of ISI in conjunction with underwater acoustic channel modeling are applied to the underwater simulation of communication. The performance of these methods in the simulation guide to possibility of adopting in underwater acoustic communication algorithm. For this purpose, we compare SER performance of SC-FDE with that of OFDM for modelled underwater channel. Underwater channel is generated by Bellhop model. Simulation results show above 5dB SNR gain at 10-3 SER. And it demonstrate SC-FDE is efficient method for underwater acoustic communication.

• Journal of the Korean Association of Geographic Information Studies
• /
• v.16 no.3
• /
• pp.147-163
• /
• 2013

The purpose of this study is to compare precipitation distributions in precipitation data sets over South Korea produced by three interpolation methods. The differences of precipitation caused by interpolation methods is an important information when the interpolated precipitation data sets were used in researches such as ecological and hydrological modeling as well as regional climate impact studies. In this study, the precipitation data sets were produced by IDW(Inverse Distance Weighting) and Cokriging in this study and the PRISM(Precipitation-elevation Regressions on Independent Slopes Model) data set obtained from Climate Change Information Center of Korea. The spatial resolution of the precipitation data is 1km. As a result, there was a great precipitation difference caused by interpolation methods in data of mountainous watersheds in general. Especially the difference of monthly precipitation was 10~20% or more in the mountainous watersheds near the Military Demarcation Line dividing North and South Korea, Mt. Sobaik, Mt. Worak, Mt. Deogyu, Mt. Jiri and Taeback Mountain Range. It means that a final result of a research can be affected by adopted interpolation method when an interpolated precipitation data set is used in the research for the these study sites.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.24 no.1
• /
• pp.98-105
• /
• 2013

This paper presents a finite-difference time-domain(FDTD) simulation and a data processing technique for radar sensing of the internal structure of a wall using an ultra-wide band antenna. We first designed an ultra-wide band anti-podal vivaldi antenna with a frequency range of 0.3~7 GHz which is chosen to be relatively low after considering the characteristics of wave attenuation, wall penetration, and range resolution. In this study the two-dimensional FDTD technique was used to simulate a wall-penetration-radar experiment under practical conditions. The next, the measured radiation pattern of the practical antenna is considered as an equivalent source in the FDTD simulation, and the reflection data of a concrete wall and targets are obtained by using the simulation. Then, a data processing technique has been applied to the FDTD reflection data to get a radar image for remote sensing of the internal structure of the wall. We compared the two different source excitations in the FDTD simulation; (1) commonly-used isotropic point sources and (2) polynomial curve fitting sources of the measured radiation pattern. As a result, when we apply the measured antenna pattern into the FDTD simulation, we could obtain about 2.5 dB higher signal to noise level than using a plane wave incidence with isotropic sources.

• Journal of the Korea Society for Simulation
• /
• v.26 no.2
• /
• pp.41-49
• /
• 2017

In the acquisition program, the conceptual design is the most important step toward specifying the military objectives, establishing requirements and determining future developmental directions, of a target system. However, if both the requirements and directions are incorrectly set due to the lack of development experiences and literature backgrounds in the target systems, such as future ground combat vehicles, it may become a major risk in the future design phases and the entire acquisition program. In order to correct these errors in the future phases, time, effort and cost are required. Therefore, it is necessary to reduce the errors that occur in the initial stages to effectively acquire the future ground combat vehicles. This paper describes the initial design method for verifying the requirements and the developmental directions and estimating the system performance at the conceptual design through the system-level physical modeling and simulation (M&S) and the target system performance analysis. The system-level physical M&S use cutting-edge design tools, model-based designs and geometric-based designs. The system performance estimation is driven from the results of the system-level physical M&S and the specialized system analysis software.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.19 no.11
• /
• pp.78-87
• /
• 2018

This study constructed a structural model and examined the fit and significance of the model to identify the influencing factors on the organizational commitment of ROTC cadets. The subjects of this study were 209 male students in grades 3 and 4 ROTC cadets of eight universities located in D, P, and G cities. Data were collected from April 13 to May 29, 2018. The data collected were analyzed by SPSS / WIN 20.0 and AMOS 21.0 programs. A positive correlation was observed between the ROTC instructor's leadership, self-efficacy, job satisfaction, and organizational commitment. Six of the six pathways of the hypothetical structural model were statistically significant. The hypothetical model showed a good fit for the data. The model fit indices were ${\chi}^2/df=1.51$, GFI=.98, AGFI=.90, NFI=0.98, NFI=.97, RMR=.02, RMSEA=.05, and TLI=.98. The ROTC Instructor's leadership and self-efficacy had direct and indirect effects on the organizational commitment. Job satisfaction had the strongest direct influence on organizational commitment. This model explained 73% of the variance in organizational commitment. Therefore, it is necessary to develop an effective education and intervention program that can enhance the ROTC instructor's leadership, self-efficacy, and job satisfaction to increase the organizational commitment of the ROTC cadets.