• Geomechanics and Engineering
• /
• 제20권6호
• /
• pp.517-525
• /
• 2020

The long-term stability of rock engineering is significantly affected by the time-dependent deformation behavior of rock, which is an important mechanical property of rock for engineering design. Although the hard rocks show small creep deformation, it cannot be ignored under high-stress condition during deep excavation. The inner mechanism of creep is complicated, therefore, it is necessary to investigate the relationship between microscopic creep mechanism and the macro creep behavior of rock. Microscopic numerical modeling of sandstone creep was performed in the investigation. A numerical sandstone sample was generated and Parallel Bond contact and Burger's contact model were assigned to the contacts between particles in DEM simulation. Sensitivity analysis of the microscopic creep parameters was conducted to explore how microscopic parameters affect the macroscopic creep deformation. The results show that the microscopic creep parameters have linear correlations with the corresponding macroscopic creep parameters, whereas the friction coefficient shows power function with peak strength and Young's modulus, respectively. Moreover, the microscopic parameters were calibrated. The creep modeling curve is in good agreement with the verification test result. Finally, the creep curves under one-step loading and multi-step loading were compared. This investigation can act as a helpful reference for modeling rock creep behavior from a microscopic mechanism perspective.

• 한국콘텐츠학회:학술대회논문집
• /
• 한국콘텐츠학회 2005년도 춘계 종합학술대회 논문집
• /
• pp.131-137
• /
• 2005

최근 중앙선과 태백선의 국철구간에 대한 복선화 사업이 시작되면서 도심지에 비해 지형이 험준하고 경사가 급한 산악지에서의 철도설계와 공사의 어려움이 예상되고 있다. 본 연구에서는 지형이 험준한 산악지에서의 복선철도 신설구간에 대한 3차원 지형분석과 가상주행을 통하여 설계 및 시공 이전에 대상지역의 인공위성영상의 활용을 구체적으로 적용함으로서 좀 더 상세한 지형에 대한 정보수집과 분석을 시도하였다. 약 150 구간의 산악지에 대한 3차원 지형분석과 복선철도노선과의 관계를 확인하고 가상주행을 실제 적용해 봄으로서 기존의 방법을 개선할 뿐만 아니라 산악지의 복선철도 구간의 지형분석의 방법을 제시하여 새로운 방법의 가능성을 찾아낼 수 있었다.

• 품질경영학회지
• /
• 제45권4호
• /
• pp.829-846
• /
• 2017

Purpose: This paper compares the effectiveness of typical selective assembly criteria and suggests the most promising one. Based on the result of a computer simulation, the key issues of selective assembly are examined and the best criterion is recommended from the effectiveness perspective. Methods: Using JAVA program, production of ten thousand units for each pair of components are simulated for selective assembly of the two types. And the number of mismatching and the fraction nonconforming for each criterion are determined. Results: The best match criterion appeared to be most promising from the perspectives of both mismatching and nonconforming problems. Its effectiveness appears to be also good even when the precision of one component is different from that of the other. Conclusion: For designing an optimal method for selective assembly, the best match criterion is recommendable as the base criterion.

• EDISON SW 활용 경진대회 논문집
• /
• 제6회(2017년)
• /
• pp.677-687
• /
• 2017

Caffeine has a long history of human consumption but the consumption of caffeine due to caffeinated energy drinks(CEDs) is rapidly growing. Marketing targets of CED sales are children, adolescents and young adults, possibly caffeine-sensitive groups and its effect for them can be significantly different from healthy adults. Caffeine-related toxicities among these groups are growing in number and a number of countries are recognizing severity of caffeine toxicities. Previous research showed prediction of maximal plasma caffeine concentration profiles after the single CED ingestion and the primary aim of this study is to visually predict plasma caffeine concentration after the single and multiple ingestion of standard servings of CED. Based on the population pharmacokinetic model using Monte Carlo simulation, prediction of caffeine concentration leading to caffeine intoxication in the sensitive groups is quantitatively presented and visualized. This research also broadens the perspective by creating and utilizing diverse open science tools including R package, Edison Science App and Shiny apps.

• International Journal of Naval Architecture and Ocean Engineering
• /
• 제11권2호
• /
• pp.899-913
• /
• 2019

In order to provide a complementary perspective to the effects of the maneuvering motions on the unsteady propeller performance, the numerical simulation of the flow field of the hull-rudder- propeller system is performed by Unsteady Reynolds-averaged Naiver-Stokes (URANS) method. Firstly, the flow fields around the submarine model without the presence of propeller in straight ahead motion and the steady diving maneuvers with submergence rudder deflections of 4°, 8° and 12° are predicted numerically. The non-uniformity characteristic of the nominal wake field is exacerbated with the increase submergence rudder angle. Then the flow field around the SUBOFF-G submarine fitted with the 4381 propeller is simulated. The axial, transverse and vertical unsteady propeller forces in different maneuvering conditions are compared. In general, as the submarine maneuvers more violently, the harmonic amplitudes of the unsteady force at the 2BPF and 3BPF increased more significantly than that at BPF.

• 한국철도학회:학술대회논문집
• /
• 한국철도학회 2004년도 추계학술대회 논문집
• /
• pp.892-899
• /
• 2004

최근 중앙선과 태백선의 국철구간에 대한 복선화 사업이 시작되면서 도심지에 비해 지형이 험준하고 경사가 급한 산악지에서의 철도설계와 공사의 어려움이 예상되고 있다. 본 연구에서는 지형이 험준한 산악지에서의 복선철도 신설구간에 대한 3차원 지형분석과 가상주행을 통하여 설계 및 시공 이전에 대상지역의 인공위성영상의 활용을 구체적으로 적용함으로서 좀 더 상세한 지형에 대한 정보수집과 분석을 시도하였다. 약 15km 구간의 산악지에 대한 3차원 지형분석과 복선철도노선과의 관계를 확인하고 가상주행을 실제 적용해 봄으로서 기존의 방법을 개선할 뿐만 아니라 산악지의 복선철도 구간의 지형분석의 방법을 제시하여 새로운 방법의 가능성을 찾아낼 수 있었다.

• Geomechanics and Engineering
• /
• 제9권1호
• /
• pp.25-37
• /
• 2015

To predict the surface subsidence of salt rock storage, a new surface subsidence basin model is proposed based on the Logistic function from the phenomenological perspective. Analysis shows that the subsidence curve on the main section of the model is S-shaped, similar to that of the actual surface subsidence basin; the control parameter of the subsidence curve shape can be changed to allow for flexible adjustment of the curve shape. By using this model in combination with the MMF time function that reflects the single point subsidence-time relationship of the surface, a new dynamic prediction model of full section surface subsidence for salt rock storage is established, and the numerical simulation calculation results are used to verify the availability of the new model. The prediction results agree well with the numerical simulation results, and the model reflects the continued development of surface subsidence basin over time, which is expected to provide some insight into the prediction and visualization research on surface subsidence of salt rock storage.

• 한국철도학회:학술대회논문집
• /
• 한국철도학회 2005년도 추계학술대회 논문집
• /
• pp.475-481
• /
• 2005

최근 국내에서의 철도 교통량증가로 인하여 단일노선의 증편을 복선철도로 재설계하여 건설하려는 다각적인 방안이 논의되고 있다. 특히 경부선에 비해 일반 승객보다는 시멘트 및 산림자원의 수송량이 많은 태백선과 중앙선에 대한 복선화 전철사업이 추진되면서 부분적인 구간에 대한 설계와 건설이 이루어지고 있다. 본 연구에서는 중앙선의 중간지점이 되고 있는 제천과 도담 구간에 대한 공간정보의 적용과 태백선의 출발지점인 제천과 쌍용구간에 대한 영상정보의 적용의 결과를 비교하여 분석하였다. 이러한 연구결과를 통하여 다각적인 방법으로 최적의 노선성정방안을 도출하고자 하였다.

• Wind and Structures
• /
• 제16권5호
• /
• pp.433-455
• /
• 2013

A phase delay spectrum model towards the representation of spatial coherence of stochastic wind fields is proposed. Different from the classical coherence functions used in the spectral representation methods, the model is derived from the comprehensive description of coherence of fluctuating wind speeds and from the thorough analysis of physical accounts of random factors affecting phase delay, building up a consistent mapping between the simulated fluctuating wind speeds and the basic random variables. It thus includes complete probabilistic information of spatial stochastic wind fields. This treatment prompts a ready and succinct scheme for the simulation of fluctuating wind speeds, and provides a new perspective to the accurate assessment of dynamic reliability of wind-induced structures. Numerical investigations and comparative studies indicate that the developed model is of rationality and of applicability which matches well with the measured data at spatial points of wind fields, whereby the phase spectra at defined datum mark and objective point are feasibly obtained using the numerical scheme associated with the starting-time of phase evolution. In conjunction with the stochastic Fourier amplitude spectrum that we developed previously, the time history of fluctuating wind speeds at any spatial points of wind fields can be readily simulated.

• 한국시스템다이내믹스연구
• /
• 제6권1호
• /
• pp.125-145
• /
• 2005

The Sihwaho Project got off to a bad start, which led to a series of mishaps and an imbalance of the whole project. The purpose of this study is to select the case of Sihwaho as a research subject, clean up the contamination caused by the ill planned project, develop suitable measures to stabilize the lake environment, and find the implications of similar development projects. For this, the authorshave conducted three simulations after studying the structural reasons for the failure of the Sihwaho Policy by identifying cause and effect relationships, pre-testing a number of policy measures for the current lake project, and presenting measures for solving the contamination problem at the lake. The simulations have shown us that filling the lake with seawater is inadequate to solve the problem and that we also have to make efforts to reduce the volume of wastes to the lake as well. The authorshave also analyzed the degree of difference between the simulation and survey results for scenario 1, in which we have studied how much seawater can reduce the contamination of the Sihwaho Lake without the effort to reduce the volume of wastes into the lake. The survey showed that most citizens and employees of the Ministry of Environment did not think it would be serious as the simulation results pointed out, and the employees of the Ministry of Environment were more optimistic about the situation than the public.