• Proceedings of the Korean Society for Rock Mechanics Conference
• /
• 2000.09a
• /
• pp.93-103
• /
• 2000

The concrete plug in an underground cavern prevents the stored product (oil, gas, etc) from leaking and the excessive show of underground water, so it plays an important role in construction and operation of the storage cavern. Additionally, it should maintain its stability under every possible loading condition. Once the plug is constructed, the cavern is isolated from the external access. Therefore, mechanical and hydraulic consideration should be made in construction to fulfill its function. Therefore, in this study, numerical analyses were conducted to study the optimal shape and thickness of the plug with respect to the various conditions of installation depth, the shape of the plug, in-situ stress ratio (K), the condition of rock-plug interface, and the effect of Excavation Damaged Zone (EDZ). This paper also presents the effect of slot depth on the hydraulic behavior of the plug. These analyses were carried out by using the 2-dimensional finite difference code, rm FLAC, and the 3D code, m FLA $C^{3D}$./.

• Tunnel and Underground Space
• /
• v.10 no.3
• /
• pp.344-354
• /
• 2000

The concrete plug in an underground cavern prevents the stored product (oil, gas, etc) from leaking and the excessive inflow of underground water, so it plays an important role in construction and operation of the storage cavern. Additionally, it should maintain its stability under every possible loading condition. Once the plug is constructed, the cavern is isolated from the external access. Therefore, mechanical and hydraulic consideration should be made in construction to fulfill its function. Therefore, in this study, numerical analyses were conducted to study the optimal shape and thickness of the plug with respect to the various conditions of installation depth, the shape of the plug, in-situ stress ratio (K), the condition of rock-plug interface, and the effect of Excavation Damaged Zone (EDZ). This paper also presents the effect of slot depth on the hydraulic behavior of the plug. These analyses were carried out by using the 2-dimensional finite difference code, rm FLAC, and the 3D code, rm FLAC$\^$3D/.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.38 no.1
• /
• pp.17-23
• /
• 2014

Graphics processing units (GPUs) are ideal for solving problems involving parallel data computations. In this study, the GPU is used for effectively carrying out a multi-body dynamic simulation with particle dynamics. The Hilber-Hushes-Taylor (HHT) implicit integration algorithm is used to solve the integral equations. For detecting collisions among particles, the spatial subdivision algorithm and discrete-element methods (DEM) are employed. The developed program is verified by comparing its results with those of ADAMS. The numerical efficiencies of the serial program using the CPU and the parallel program using the GPU are compared in terms of the number of particles, and it is observed that when the number of particles is greater, more computing time is saved by using the GPU. In the present example, when the number of particles is 1,300, the computational speed of the parallel analysis program is about 5 times faster than that of the serial analysis program.

• Proceedings of the Korean Fiber Society Conference
• /
• 2003.04a
• /
• pp.398-399
• /
• 2003

의복 쾌적감은 착용자가 환경변화에 대하여 쾌적한 감정을 갖는 것을 의미한다. 직물의 쾌적성은 접촉감 뿐만 아니라 공기, 열, 수분을 전달하는 직물의 물리적 특성과 관계가 있는데 특별히 직물의 표면특성과 관련하여 변화하는 쾌적인자는 온냉감과 열, 수분 및 공기전달성이다. 따라서 직물의 표면 형태 및 두께에 따라 열, 수분 및 공기전달 특성은 달라질 뿐만 아니라 인체에 접촉하였을 때 접촉면적이 달라지므로 촉감에 큰 영향을 미친다. 본 연구에서는 의복의 쾌적성 향상의 중요한 인자로 대표적인 직물의 역학 특성과 열 및 수분전달특성을 직물 구성사의 단면형상을 달리하였을 때의 그 상관 관계에 대하여 알아보았다. (중략)

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.24 no.2 s.173
• /
• pp.411-420
• /
• 2000

This paper presents a new method for calculating contact position and contact force. The proposed method calculates accurate contact position by introducing intermediate parameters. Accurate contac t force can be obtained by solving reduced equations of motion iteratively. This method can be applied to calculate not only contact force on contact points but also contact force on kinematic joints such as a rotational joint and a translational joint. Four numerical examples are given to demonstrate the effectiveness of the proposed algorithm.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2004.05a
• /
• pp.73-76
• /
• 2004

Tapping mode atomic force microscopy (TM-AFM) utilizes the dynamic response of a resonating probe tip as it approaches and retracts from a sample to measure the topography and material properties of a nanostructure. We present recent results based on numerical techniques that yield new perspectives and insight into AFM. It is compared that the dynamic models including van der Waals and Derjaguin-Muller-Toporov(DMT) or Johnson-Kendall-Roberts(JKR) contact forces demonstrates that periodic solutions can be represented with respect to the approach distance and excitation frequency.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.9 no.6
• /
• pp.152-159
• /
• 2001

In multibody dynamic analysis including contact and impact, there are two major analysis methods, i.e., piecewise analysis and continuous analysis. Modeling of contact phenomena is mainly classified with a Kelvin-Voigt model or a model of Hertz contact model. In this paper, a contact module fur AutoDyn7 program was developed and implemented. Both the Kelvin-Voigt model and a model of Hertz contact law were developed. The process of this module is composed of contact distinction and the contact force calculation. Two examples were verified and compared to the commercial program DADS.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2009.06a
• /
• pp.195-196
• /
• 2009

• Proceedings of the KSLP Conference
• /
• 2007.03a
• /
• pp.14-14
• /
• 2007

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.35 no.6
• /
• pp.325-331
• /
• 2022

Hydrogen embrittlement in metals has been a serious issue with regard to structural safety. In this study, molecular dynamics simulations revealed that the aggregation of hydrogen atoms at the crack tips suppresses the dislocation emission and thus results in cleavage fracture. A series of molecular dynamics simulations were performed considering factors such as the concentration of hydrogen atoms, loading rate, and diffusion coefficient. We investigated the conditions that minimize hydrogen embrittlement. The simulation results were consistent with the experimental results and used to quantify hydrogen embrittlement.