• Advances in aircraft and spacecraft science
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• 제5권2호
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• pp.239-249
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• 2018

Physical tests are performed at various stages of the development cycle of a product, from prototype validation to product qualification. Although costly, there are growing demands for qualification tests like endurance vibration testing to be more representative of the real world. At the same time there are growing demands to assess the durability of these items based on FEA simulation. In this paper, we will explain how to set up a CAE-based test and how to correlate the results with some physical measurements. Specific assumptions will be explained and some advantages of using virtual tests will be highlighted such as the reduction of the number of prototypes needed, investigations on failures, evaluation of the level of reliability via sensitivity analysis, evaluation of the margins are at the end of a successful test. This presentation will therefore focus on explaining and showing how virtual tests can enrich the exploitation of physical tests.

• International Journal of Naval Architecture and Ocean Engineering
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• 제12권1호
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• pp.957-966
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• 2020

This paper presents the virtual mass method to implement the prediction of total resistance for ice-going ship in floe ice region based on the combined method of CFD and DEM. Two ways of floe ice distribution are adopted for the analysis and comparison. The synthetic ice model test has been conducted to determine the optimal virtual mass coefficients for the two different floe ice distributions. Moreover, the further verification and prediction are developed in different ice conditions. The results show that, the fixed and random distributions in numerical method can simulate the interaction of ship and ice vividly, the trend of total resistance varying with the speed and ice concentration obtained by the numerical simulation is consistent with the model test. The random distribution of floe ice has higher similarity and better accuracy than fixed distribution.

• 한국의류산업학회지
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• 제16권1호
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• pp.128-136
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• 2014

The virtual try-on technologies of the current level have limitations with material expression as well as some difficulties with commercialization. There are differences in simulation results and subjective evaluations perceived by consumers according to the types and physical characteristics of materials used in virtual try-on simulations. This study were to analyze the exterior clothing shapes and visual images from 3D virtual try-on simulations with materials whose drapability was differentiated and then test the accuracy of the expression of the drapability of the materials. The study carried out 3D virtual try-on simulations by selecting flared skirts as an item to best express differences in drapability along with five materials of different physical properties and offered some basic data for greater utilization of virtual try-on simulations by comparing and analyzing them with the exterior shapes and visual images of actual flared skirts. The analysis results of hemline shapes between actual and virtual try-on according to the types of materials showed no match among the quantitative items of exterior shapes factors. There were no significant differences in the visual images except for "soft" according to the simulation methods, which means that the items can serve as part of a scale for visual image comparison. It is necessary to reflect quantitative numbers regarding "drapability" proposed in the study simulation software and to continue to build a systematic database for virtual simulations by investigating and testing various materials.

• 한국항해항만학회지
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• 제44권2호
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• pp.53-64
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• 2020

This paper discusses the hydrodynamic characteristics of a catamaran at low speed. In this study, the Delft 372 catamaran model was selected as the target hull to analyze the hydrodynamic characteristics by using the RANS (Reynold-Averaged Navier-Stokes) numerical method. First, the turbulence study and mesh independent study were conducted to select the appropriate method for numerical calculation. The numerical method for the CFD (Computational Fluid Dynamic) calculation was verified by comparing the hydrodynamic force with that obtained experimentally at high speed condition and it rendered a good agreement. Second, the virtual captive model test for a catamaran at low speed was conducted using the verified method. The drift test with drift angle 0-180 degrees was performed and the resulting hydrodynamic forces were compared with the trends of other ship types. Also, the pure rotating test and yaw rotating test proposed by Takashina, (1986) were conducted. The Fourier coefficients obtained from the measured hydrodynamic force were compared with those of other ship types. Conversely, pure sway test and pure yaw test also were simulated to obtain added mass coefficients. By analyzing these results, the hydrodynamic coefficients of the catamaran at low speed were estimated. Finally, the maneuvering simulation in low speed conditions was performed by using the estimated hydrodynamic coefficients.

• 한국멀티미디어학회논문지
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• 제24권10호
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• pp.1435-1448
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• 2021

Recent years, due to the direct or indirect damages caused by meteorological disasters more and more attention have been paid to natural disasters. At same time, diversified and multi-sensory interactive meteorological services is increasingly demanded. In this study, novel interactive meteorological service was compared with the traditional communication methods. Combining with case studies and systems creation, a virtual reality weather simulation framework was proposed, and a realistic virtual game environment providing real-time and historical weather information was created. The primary goal of this study is to build a weather display cabinet game system by using virtual reality technology, and promoting public's understanding of the principles of weather changes. With the interactive games in realistic scenarios, public's awareness for disasters prevention could be promoted. It is helping to change public's traditional understanding of meteorological theories, and will provide a more convenient way for the public to explore more effective weather forecasts. The simulation system is supported by VR technology. It was combined with Leap Motion interactive equipment to make popularization games for weather science. T-test data analysis showed that the application of VR technology in weather games has strong operability and interactivity.

• 한국시뮬레이션학회논문지
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• 제28권2호
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• pp.169-177
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• 2019

전장상황의 변화와 첨단정보통신기술의 발전에 따라 과학화된 훈련체계인 LVC 훈련체계가 주목을 받고 있다. 대한민국 공군은 전투기 시뮬레이터를 중심으로 공중전투기동장비(ACMI), 워게임모델을 가상의 합성전장환경에 구현하여 실전적이고 과학적인 훈련이 가능한 LVC 훈련체계를 구축하고자 한다. 본 논문에서는 공군의 Virtual 체계인 전투기 시뮬레이터와 Constructive 체계인 전구급 연습용 모델의 V-C 연동시험 수행결과에 대해 다루고자 한다. 기종별로 각각 상이한 연동방식을 갖춘 F-15K, KF-16, FA-50 전투기 시뮬레이터를 표준 연동방식으로 변환하였으며, 합성 전장환경 모의 도구를 활용하여 3개 기종의 전투기 시뮬레이터가 상호 연동이 가능한 환경을 구축하였다. 그리고 공군의 연습용 모델인 창공모델도 표준 연동방식으로 변환하였으며, 연동 최적화를 위해 SW 일부를 수정하였다. 이를 통해 공군의 전투기 시뮬레이터와 워게임 모델이 연동이 가능함을 확인할 수 있었다. 본 연구결과는 향후 공군 LVC 훈련체계 개념연구 및 체계개발 간에 유의미하게 참조할 만한 근거가 될 것임을 기대한다.

• 한국전자파학회논문지
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• 제29권6호
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• pp.457-463
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• 2018

이 논문에서는 실제 레이다를 이용하여 획득한 신호와 시뮬레이션으로 획득한 신호에 ${\Sigma}{\Delta}-STAP$ 알고리즘을 적용하여 비교하였다. 시험은 무반향 챔버에서 모의신호 발생장치를 이용한 표적 신호와 신호발생기를 이용한 클러터 신호를 레이다로 수신하여 수행하였다. 시뮬레이션은 시험과 동일한 레이다 파라미터에 이상적인 기저대역 신호 모델링을 통하여 수행하였다. 비교 결과, ${\Sigma}{\Delta}-STAP$ 처리된 거리-도플러 맵은 표적 신호의 형태나 잡음 수준이 시뮬레이션과 시험 결과가 거의 유사하였다. SINR 손실의 경우, 두 결과가 비슷한 양상을 보이나, 시뮬레이션 결과가 1~2 dB 가량 높은 값을 보였다. 이를 통하여 일반적인 레이다 신호 시뮬레이션을 수행하여도 실제 시험 결과와 유사한 ${\Sigma}{\Delta}-STAP$ 처리 결과를 얻을 수 있음을 확인하였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 제38회 하계학술대회
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• pp.1191-1192
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• 2007

In this paper we deal with a design of the evaluation system to assess the vehicle operational control algorithm for Personal Rapid Transit(PRT) system. PRT system is different from the conventional rail traffic system in such point that the station is off-line so as to guarantee a very short headway. In this study we propose a evaluation system to assess the performance of the proposed vehicle control algorithm. The evaluation system is composed of virtual vehicles, central control system, virtual wayside facilities, monitoring equipments. In order to test the proposed evaluation system a test algorithm is used, which has been simulated in the combined simulation system between Labview Simulation Interface Toolkit and Matlab/Simulink.

• 한국해양공학회:학술대회논문집
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• 한국해양공학회 2002년도 추계학술대회 논문집
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• pp.174-180
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• 2002

A virtual reality technology for multipurpose numerical simulation is developed to reproduce and investigate a variety of ocean environmental problems in a 3D-Numerical Wave Tank. The governing equations for solving incompressible fluid motion are Navier-Stokes equation and continuity equation, and the Marker-Density function technique is adopted to implement the fully-nonlinear free-surface kinematic condition. The marine environmental situations, i.e. waves, currents, wind, etc., are reproduced by use of multi-segmented wavemaker on the basis of the so-called "snake-principle". In this paper, some numerical reproduction techniques for regular and irregular waves, multi-directional waves, Bull's-eye wave, wave-current, and solitary wave are presented, and a model test in motion with large amplitude of roll angle is conducted in the developed 3D-NWT, using a overlaid grid system.

• 한국응급구조학회지
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• 제22권3호
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• pp.67-76
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• 2018

Purpose: The purpose of this study was to evaluate the quality of chest compressions and ventilation when using an mechanical device(LUCAS) and 2-men manual cardiopulmonary resuscitation(CPR) performed on a minikin, as well as to propose a more effective CPR method during transit. Methods: Data were collected by LUCAS and manual virtual reality based ambulance simulation. Analysis was performed using SPSS software 12.0. The average and standard deviation of chest compression depth and ventilation were analyzed using descriptive statistics and t-test. Results: In the virtual reality based LUCAS and manual CPR results, LUCAS showed better chest compression and lower incomplete chest release than manual CPR. During CPR with a chest compression-ventilation ratio of 30:2 in virtual reality ventilation with bag-valve mask was able to deliver an adequate volume of breathing. Conclusion: It is suggested that rescuers on ambulance may consider using LUCAS as an alternative to high-quality chest compression during transit.