• 한국지반공학회:학술대회논문집
• /
• 한국지반공학회 2009년도 세계 도시지반공학 심포지엄
• /
• pp.194-205
• /
• 2009

In geotechnical engineering, the mechanical characteristics of soil, the main material of geotechnical engineering, is highly related to the confining stress. Reduced-scale physical modeling is often conducted to evaluate the performance or to verify the behavior of the geotechnical systems. However, reduced-scale physical modeling cannot replicate the behavior of the full-scale prototype because the reduced-scale causes difference of self weight stress level. Geotechnical centrifuges are commonly used for physical model tests to compensate the model for the stress level. Physical modeling techniques using centrifuge are widely adopted in most of geotechnical engineering fields these days due to its various advantages. In this paper, fundamentals of geotechnical centrifuge modeling and its application area are explained. State-of-the-art geotechnical centrifuge equipment is also described as an example of KOCED geotechnical centrifuge facility at KAIST.

• 한국전문물리치료학회지
• /
• 제14권2호
• /
• pp.1-10
• /
• 2007

The purpose of this experiment was to investigate the applicability of audio-visual modeling for improving the efficiency of rehabilitative programs by analyzing the effects of observing these various models on the capacity of stroke patients to perform upper limb activities. Twenty-one stroke patients participated in the experiment and were randomly assigned to either task modeling, sport modeling, or control group. During 2 weeks of intervention, subjects in all groups participated in the physical practice of experimental tasks. These tasks comprised of a Nine Hole Peg Test, the Jebsen-Taylor Hand Function tests, and locomotion. These tasks were performed 5 days a week, 30 min per day. In addition to the physical practice, the task modeling group observed a model performing experimental tasks and locomotive activities for 20 min, while the sport modeling group observed a model performing various sport activities for 20 min. Subjects' ability to perform the experimental tasks was measured 3 times, before, immediately after, and 1 week after the intervention. Analyses of the capacity to perform upper extremity activities displayed significant improvement from the pre-test to immediate and delayed post-tests in all groups. However, the amount of improvement was the highest in the task modeling group. The task modeling group was superior to the control group in the post-test of all experimental tasks, whereas the sport modeling group did not display significant differences from the control group. These results suggest that audio-visual modeling can be used as an effective cognitive intervention for facilitating the rehabilitation of stroke patients, and its rehabilitative effect can be maximized when the program is comprised of performance scenes directly related to the target task.

• 한국정보통신학회논문지
• /
• 제22권5호
• /
• pp.740-746
• /
• 2018

지금까지 컴퓨터악기 제작시도는 크게 샘플링 (sampling)방식과 피지컬 모델링(physical modeling)의 2가지 방식이 주를 이루었다. 샘플링 방식은 샘플링 과정에서 배음의 많은 부분이 삭제되기 때문에 현의 배음을 강조하는 익사이터(exciter) 효과가 미미하다. 하지만 피지컬 모델링 방식에서는 많은 배음을 지닌 음을 만들어 낼 수 있으며 이 배음 중 특별한 주파수대의 배음을 강조함으로써 더욱 실음에 가까운 음색을 만들어 낼 수 있다. 여기서는 현의 피지컬 모델링에 있어서 현의 특정 주파수대의 배음을 강조하는 익사이터를 구현함에 있어 화이트노이즈(백색소음)을 이용하는 방법을 제안한다. 그리고 가야금 소리의 엔벨로프(envelope)와 스펙트럼 비교를 통해 익사이터를 갖는 피지컬모델링 방식이 샘플링 방식 및 기존의 피지컬 방식보다 실제 가야금 소리에 더 적합함을 확인하였다.

• 한국소성가공학회:학술대회논문집
• /
• 한국소성가공학회 2001년도 추계학술대회 논문집
• /
• pp.297-300
• /
• 2001

Physical modeling technique is applied to investigate foam generation in molten aluminum. By using room temperature water with specially designed equipment, the effects of stirrer type, fluid viscosity(glycerine added to water) and stirring velocity on foam generation behaviors are intensively analysed The distribution and size of bubbles varied with each process parameters but the most important parameters are stirring velocity and fluid viscosity. The results obtained from physical simulation have been confirmed by actual aluminum foam generation experiment at various process variables.

• 한국수자원학회:학술대회논문집
• /
• 한국수자원학회 2008년도 학술발표회 논문집
• /
• pp.449-453
• /
• 2008

This research focused on analyzing and comparing between the results of hydraulic physical modeling and the results of numerical modeling of Grass Concrete which is newly developed in-situ block system. The physical model was built as a scale of 1:50 by Froude similitude measuring the water levels and the water velocities for before and after vegetation and the effects were analyzed after reviewing the results. In consequence, the water velocities were observed to decrease meanly 19.1%, and the water depth were determined to increase meanly 27.8% in case of the of design flood, $Q=200m^3/sec$. Moreover, the velocities were produced reduction effects of 27.2%, and the water levels were derived from addition effects of the highest 31.3% in case of the probability maximum flood(PMF), $Q=600m^3/sec$. To verifying the hydraulic physical modeling, the numerical modeling was conducted for a close examination of before and after vegetation. HEC-RAS model was for 1 dimensional numerical analysis and RMA-2 was for 2 dimensional numerical analysis. The results of the numerical simulation, under the condition of roughness coefficient calibration, shows similar results of the physical modeling. These satisfactory results show that the accomplished results of hydraulic modeling and the predicted results of numerical modeling corresponded reasonably each others.

• 한국마린엔지니어링학회:학술대회논문집
• /
• 한국마린엔지니어링학회 2005년도 후기학술대회논문집
• /
• pp.156-157
• /
• 2005

Gas hydrate is ice-like crystalline lattice, formed at appropriate temperature and pressure, in which gas molecules are trapped. It is worldwide popular interesting subject as a potential energy. In korea, a seismic survey for gas hydrate have performed over the East sea by the KIGAM since 1997. In this paper, we had conducted numerical and physical modeling experiments for seismic properties on gas hydrate with field data which had been acquired over the East sea in 1998. We used a finite difference seismic method with staggered grid for 2-D elastic wave equation to generate synthetic seismograms from multi-channel surface seismic survey, OBC(Ocean Bottom Cable) and VSP(Vertical Seismic Profiling). We developed the seismic physical modeling system which is simulated in the deep sea conditions and acquired the physical model data to the various source-receiver geometry. We carried out seismic complex analysis with the obtained data. In numerical and physical modeling data, we observed the phase reversal phenomenon of reflection wave at interface between the gas hydrate and free gas. In seismic physical modeling, seismic properties of the modeling material agree with the seismic velocity estimated from the travel time of reflection events. We could easily find out AVO(Amplitude Versus Offset) in the reflection strength profile through seismic complex analysis.

• 소성∙가공
• /
• 제16권2호
• /
• pp.107-112
• /
• 2007

In this study, the mechanical joining process for double sheet metals was investigated by using physical modeling method. Process parameters of mechanical joining such as friction coefficient, drawing depth, pouch radius, die radius and material thickness are preliminarily analyzed by finite element method. Referring to the finite element analysis results mechanical joining system is designed on the basis of physical similarities. From the physical modeling test, the effect of process parameters on the deformation for the mechanical joining are experimentally investigated and optimized joining shape that can provide strong joining strength is obtained.

• Geomechanics and Engineering
• /
• 제35권4호
• /
• pp.425-436
• /
• 2023

An effective tool for researching actual problems in geotechnical and mining engineering is to conduct physical modeling tests using similar materials. A reliable geometric scaled model test requires selecting similar materials and conducting tests to determine physical properties such as the mixing ratio of the mixed materials. In this paper, a method is proposed to determine similar materials that can reproduce target properties using a polynomial model based on experimental results on modeling materials using a gypsum-sand mixture (GSM) to simulate rocks. To that end, a database is prepared using the unconfined compressive strength, elastic modulus, and density of 459 GSM samples as output parameters and the weight ratio of the mixing materials as input parameters. Further, a model that can predict the physical properties of the GSM using this database and a polynomial approach is proposed. The performance of the developed method is evaluated by comparing the predicted and observed values; the results demonstrate that the proposed polynomial model can predict the physical properties of the GSM with high accuracy. Sensitivity analysis results indicated that the gypsum-water ratio significantly affects the prediction of the physical properties of the GSM. The proposed polynomial model is used as a powerful tool to simplify the process of determining similar materials for rocks and conduct highly reliable experiments in a physical modeling test.

• 한국지반공학회:학술대회논문집
• /
• 한국지반공학회 2007년 가을학술발표회
• /
• pp.542-557
• /
• 2007

Contamination of subsurface results in degradation of geomaterials (i.e., soils and rock mass), in the long run. This is mainly due to the presence of chemical and/or radiological materials in undesirable concentrations and at elevated temperatures. However, as contaminant-geomaterial interaction is an extremely slow and complex process, which primarily depends on their physical, chemical and mineralogical properties, it is quite difficult to study this interaction under laboratory or in situ conditions. In such a situation, accelerated physical modeling, using a geotechnical centrifuge, and finite element/difference based numerical modeling techniques are found to be quite useful. This paper presents details of various modeling techniques developed by the researchers at the Indian Institute of Technology Bombay, Mumbai, India, for studying heat migration, flow and interaction (fate) of reactive and non-reactive contaminants in the geoenvironment, under saturated and unsaturated conditions. In addition, paper presents details of the technique that can be employed for determining susceptibility of a material to undergo physico-chemico-mineralogical alterations due to its interaction with contaminants.

• 로봇학회논문지
• /
• 제3권2호
• /
• pp.112-116
• /
• 2008

This paper presents URS (Ubiquitous Robotic Space) Modeling and service technique for the robotic security service while bridging between virtual space and physical space. First, this paper introduces a concept of virtual URS and responsive virtual URS. Second, this paper addresses modeling of URS which covers modeling of indoor geometry and environment sensor. Third, this paper describes virtual URS services including interactive virual-physical bridging service.