• Title/Summary/Keyword: Virtual mass method

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The Development of Fashion Design with Korean Images Using Digital Media - 3D Modeling Based On Maya (Qualoth) Program - (디지털 매체를 활용한 한국적 이미지 패션 디자인 개발 - Maya(Qualoth) 프로그램을 활용한 3차원 모델링 -)

  • Lee, Yoon-Kyung;Kim, Min-Ja
    • Journal of the Korean Society of Costume
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    • v.58 no.6
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    • pp.42-53
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    • 2008
  • This study is about the development of Fashion Design using of Korean Motive applied Digital Medium. With rapid change during the 21st century, digital media has emerged as the most important communication tool to facilitate speedy and interactive conversation. The recent emergence of 'Mass Customization' is a good reflection of digital transition's interactive features, realizing product variation and customization through flexibility and immediate responsiveness. In this so-called digital era, fashion is a tool that facilitates the use of digital media, while acting as the object, or the purpose, where digital media can be applied. This study looked at the development situations and future utilization method regarding digital fashion, which was recreated through digital media. In this study, a new design process was developed through digital media and actually manufactured Korean image clothing to reflect the motif of plant found in Korean folk paintings. Three-Dimensional(3D) digital shape was dressed in virtual clothing for comparison, thereby adding some features of textile design to three-Dimensional(3D) shape. Through the process, the study can provide various potential accesses to future development of fashion design utilizing digital media.

Experimental Modal Analysis of Perforated Rectangular Plates Submerged In Water (물에 잠긴 다공 직사각평판의 실험적 모드 해석)

  • 유계형;이명규;정경훈;이성철
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.13 no.1
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    • pp.70-78
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    • 2003
  • This paper dealt with an experimental study on the hydroelastic vibration of clamped perforated rectangular plates submerged in water. The penetration of holes in the plates had a triangular pattern with P/D (pitch to diameter) 1.750, 2.125, 2.500, 3.000 and 3.750. The natural frequencies of the perforated plates in air were obtained by the analytical method based on the relation between the reference kinetic and maximum potential energy and compared with the experimental results. Good agreement between the results was found for the natural frequencies of the perforated plates in air. It was empirically found that the natural frequencies of the perforated plate in air increase with an increase of P/D, on the other hand, the natural frequencies of the perforated plate in contact with water decrease with an increase of P/D. Additionally. the effect of the submerged depth on the natural frequency was investigated.

Development of the similitude law considering the intensity-dependent variation of natural frequency of pile foundation system (말뚝 기초 고유진동수의 가속도 크기 의존성을 고려한 상사법칙 개발)

  • Choi, Jung-In;Yoo, Min-Teak;Kim, Sung-Yul;Kim, Myoung-Mo
    • Proceedings of the Korean Geotechical Society Conference
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    • 2009.09a
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    • pp.905-912
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    • 2009
  • 1-g shaking table test is conducted to evaluate the dynamic behavior of a soil-structure system under seismic loading condition. A consistent similitude law between the model and prototype is needed to predict the behavior of the prototype structure, quantitatively. The natural frequency of geomaterial decreases with the increase of shaking intensity because of the non-linear property of the geomaterial. This phenomenon affects the applicability of similitude laws in 1-g shaking table tests. In this study, a simple method is suggested to determine the frequency of the input motions in 1-g tests in order to enhance the applicability of similitude laws. Modified input frequency is calculated using the frequency ratio with consideration of the variation of the natural frequency according to the intensity of input ground acceleration. To verify the applicability of the suggested method, a series of 1-g shaking table tests were performed for three different sizes of model piles having an overburden mass on their heads by varying the acceleration and the frequency of input motion. The acceleration amplification ratio on the overburden mass, the lateral displacement at the pile head and the maximum bending moment along the pile depth were measured. The projected behaviors of the virtual prototype based on the measured values of the model tests, where the input frequencies were calculated by the new method, showed good consistency, verifying the applicability of the suggested method.

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A Numerical Simulation of Projectile Aerodynamics Using a Ballistic Range (Ballistic Range를 이용한 Projectile 공기역학의 수치모사)

  • Jung S. J.;Rajesh G.;Kim H. D.;Lee J. M.
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • v.y2005m4
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    • pp.386-393
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    • 2005
  • The objective of the present study is to develop a new type of the Ballistic range, called 'two-stage light gas gun'. A computational work has been performed to investigate the aerodynamics of a projectile which is launched from the two-stage light gas gun. A moving coordinate method for a multi-domain technique is employed to simulate unsteady projectile flows with a moving boundary. The effect of a virtual mass is added to the axisymmetric unsteady Euler equation systems. The computed results reasonably capture the major flow characteristics which are generated in launching the projectile supersonically, such as the interaction between the shock wave and the blast wave, the interaction between the vortical flow and the barrel shock, and the steady under-expanded jet. The present computational results properly predict the velocity, acceleration, and drag histories of the projectile.

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Case study on hydroelastic vibration of plate for various bounded fluid field (유체장 변화에 따른 사각형 탱크의 진동에 관한 연구)

  • Kim, K.S.;Choi, S.H.;Jo, H.D.
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2006.11a
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    • pp.855-860
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    • 2006
  • In this paper, a numerical case study is carried out on the hydroelastic vibration of rectangular plate with various fluid field. It is assumed that the tank wall is clamped along the plate edges. The VMM(Virtual Mass Method) of Nastran is used for the simulation of fluid domain and calculating natural frequency of fluid-coupled structure. In this paper, natural frequencies are calculated and compared for rectangular plates with various fluid field such as infinite fluid and finite fluid, length change of finite fluid field and various fluid contacting conditions.

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A Computational Study of the Aerodynamics of a Projectile Launched from a Ballistic Range (Ballistic Range로 부터 발사되는 Projectile 공기역학에 관한 수치해석적 연구)

  • Jun Gu-Sik;Lim Chae-Min;Kim Heuy-Dong;Lee Jeong-Min
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2006.05a
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    • pp.371-375
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    • 2006
  • A computational work has been performed to investigate the aerodynamics of a projectile which is launched from a ballistic range. A moving coordinate method for a multi-domain technique is employed to simulate unsteady projectile flows with a moving boundary. The variation of a virtual mass and the shape of projectile are added to the axisymmetric unsteady Euler equation systems. The present computational results properly predict the velocity, acceleration, drag histories and the major flow characteristics of the projectile.

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Vibration Analysis for Partially Immersed Shell Structure in Water with Gap from Bottom (부분적으로 물에 잠겨있는 Shell 구조물의 바닥면과 거리변화에 따른 진동해석 연구)

  • Koo, Jae-R.;Kwak, Moon-K.;Song, Oh-S.;Bae, Chun-H.
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.21 no.10
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    • pp.905-915
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    • 2011
  • The free flexural vibration of a hanged clamped-free cylindrical shell partially submerged in water with gap from bottom is investigated. The fluid is assumed to be inviscid and irrotational. The cylindrical shell is modeled by using the Rayleigh-Ritz method based on the Sanders shell theory. The kinetic energy of the fluid is derived by solving the boundary-value problem related to the fluid motion. The natural vibration characteristics of the partially submerged cylindrical shell are discussed with respect to the added virtual mass approach. In this study, experiments were carried out to confirm theoretical results. It was found that theoretical prediction is in good agreement with experimental results.

Display Technologies for Immersive Devices and Electronic Skin (디스플레이 현황과 발전방향 -실감 및 스킨 기기로의 확대)

  • Park, Y.J.
    • Electronics and Telecommunications Trends
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    • v.34 no.2
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    • pp.10-18
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    • 2019
  • Since the introduction of CRT(Cathode Ray Tube) in the 1950s, display technologies have been developed continuously. Flat panel displays such as PDP(Plasma Display Panel) and LCD(Liquid Crystal Display) were commercialized in the late 1990s, and OLED(Organic Light Emitting Diodes) and Micro-LED(Micro-Light Emitting Diodes) are now being developed and are becoming widespread. In the future, we expect to develop ultra-realistic, flexible, embedded sensor displays. Ultra-realistic display can be applied to AR/VR(Augmented Reality/Virtual Reality) devices and spatial light modulators for holography. The sensor-embedded display can be applied to robots; electronic skin; and security devices, including iris recognition sensors, fingerprint recognition sensors, and tactile sensors. AR/VR technology must be developed to meet technical requirements such as viewing angle, resolution, and refresh rate. Holography requires optical modulation technology that can significantly improve resolution, viewing angle, and modulation method to enable wide-view and high-quality hologram stereoscopic images. For electronic skin, stable mass production technology, large-area arrays, and system integration technologies should be developed.

A Study on the Improvement of Classification of Explosion Hazardous Area using Hypothetic Volume through Release Characteristic (누출특성을 통한 폭발위험장소 선정방법의 개선에 대한 연구)

  • Kim, Dae-Yeon;Chon, Young-Woo;Lee, Ik-Mo;Hwang, Yong-Woo
    • Journal of the Korea Safety Management & Science
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    • v.19 no.2
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    • pp.31-39
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    • 2017
  • Classify of explosion hazardous areas must be made at the site where flammable materials are used. This reason is that it is necessary to manage ignition sources in of explosion hazardous areas in order to reduce the risk of explosion. If such an explosion hazard area is widened, it becomes difficult to increase the number of ignition sources to be managed. The method using the virtual volume currently used is much wider than the result using CFD(Computational Fluid Dynamics). Therefore, we tried to improve the current method to compare with the new method using leakage characteristics. The result is a realistic explosion hazard if the light gas is calibrated to the mass and the heavy gas is calibrated to the lower explosion limit. However, it is considered that the safety factors should be taken into account in the calculated correction formula because such a problem should be considered as a buffer for safety.

Computational Modal Analyses for the Propellant Tank and Small-Scaled First-Stage Models of Liquid-Propulsion Launch Vehicles (우주 발사체 추진제 탱크 및 축소 1단 모델의 전산 모드 해석 연구)

  • Sim, Chang-Hoon;Kim, Geun-Sang;Kim, Dong-Goen;Kim, In-Gul;Park, Soon-Hong;Park, Jae-Sang
    • Journal of Aerospace System Engineering
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    • v.12 no.3
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    • pp.18-25
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    • 2018
  • This research aims to establish the finite-element modeling techniques for computational modal analyses of liquid propellants and flange joints of launch-vehicle structures. MSC.NASTRAN is used for the present computational modal analyses of the liquid-propellant tank and the small-scaled first-stage model. By means of the correlation between the measured and computed natural frequencies, the finite modeling techniques for liquid propellants and flange joints of launch-vehicle structures are established appropriately. This modal analysis using the virtual-mass method predicts well the bell mode of the liquid-propellant tank containing liquid. In addition, the present computation using RBE2 elements for modeling of flange joints predicts the first and second bending-mode frequencies within a relative error of 10%, which is better than the measured frequencies obtained from the modal test, for the small-scaled first-stage model containing liquid.