• Geomechanics and Engineering
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• v.23 no.2
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• pp.127-137
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• 2020

To study the reverse fault formation process and the stress evolution feature, a simulation test system of reverse fault formation is developed based on the analysis of reverse fault formation mechanism. The system mainly consists of simulation laboratory module, operation console and horizontal loading control system, and data monitoring system. It can represent the fault formation process, induce fault crack initiation and simulate faults of different throws. Simulation tests on reverse fault formation process are conducted by using the simulation test system: horizontal loading is added to one side of the model. the bottom rock layer cracks under the effect of the induction device. The crack dip angle is about 29°. A reverse fault is formed with the expansion of the crack dip angle towards the upper right along the fracture surface and the slippage of the hanging wall over the foot wall. Its formation process unfolds five stages: compressive deformation of rock, local crack initiation, reverse fault penetration, slippage of the hanging wall over the foot wall and compaction of fault plane. There is residual structural stress inside rock after fault formation. The study methods and results have guiding and referential significance for further study on reverse fault formation mechanism and rock stress evolution.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.24 no.6
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• pp.699-705
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• 2011

High-maneuver missile is a projectile which demands a strong momentum at short time. To produce a necessary thrust for the flight, the gas of high temperature and pressure is generated through explosive combustion of solid propellant, and a great thrust can be obtained by expanding this high temperature and pressure gas. Although the operating time of a rocket motor is less than a few seconds, a failure of part or ablation near the throat of nozzle may take place during the expansion of high temperature and pressure gas for great thrust. In other words, for the precise control of a missile an exact stress analysis considering both, the thermal stress caused by the heat transfer between combustion gas and wall, and the mechanical stress caused by the pressure change in the flow, should be considered first. In this connection, this study investigated the safety, as a point of view of stress and melting point of the material, of the pre-designed thrust generating structure which is subjected to high temperature and pressure as a function of motor operating time.

• Transactions of the Korean Society of Mechanical Engineers
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• v.15 no.6
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• pp.2002-2014
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• 1991

A refined two-dimensional analysis method, taking into account the crack opening deformation, is proposed for the evaluation of stress distributions in transverse cracked cross-ply laminates. The interlaminar stresses which play an important role in laminate failure are evaluated using the concept of interface layer. A series expansion of the displacements is employed and the thermal residual stresses and Poisson's effects in the laminated are taken into consideration in the formulation. The stress distributions are compared with finite element results. The proposed method represents well the characteristics of the stress distributions. The through-the-thickness variation of the stress distribution is remarkable near the transverse crack due to the crack opening deformation. The interlaminar stresses have significant values at the transverse crack tip and the proposed analysis can be applied as a basis for the prediction of the induced delamination onset by using appropriate failure criteria.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.04b
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• pp.95-95
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• 2009

Single-crystalline Bi nanowires have motivated many researchers to investigate novel quasi-one-dimensional phenomena such as the wire-boundary scattering effect and quantum confinement effects due to their electron effective mass (~0.001 me). Single crystalline Bi nanowires were found to grow on as-sputtered films after thermal annealing at $270^{\circ}C$. This was facilitated by relaxation of stress between the film and the thermally oxidized Si substrate that originated from a mismatch of the thermal expansion. However, the method is known to produce relatively lower density of nanowires than that of other nanowire growth methods for device applications. In order to increase density of nanowire, we propose a method for enhancing compressive stress which is a driving force for nanowire growth. In this work, we report that the compressive stress can be controlled by modifying a substrate structure. A combination of photolithography and a reactive ion etching technique was used to fabricate patterns on a Si substrate. It was found that the nanowire density of a Bi film grown on $100{\mu}m{\times}100{\mu}m$ pattern Si substrate increased over seven times higher than that of a Bi sample grown on a normal substrate. Our results show that density of nanowire can be enhanced by sidewall effect in optimized proper pattern sizes for the Bi nanowire growth.

• Journal of the Korean Institute of Gas
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• v.17 no.2
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• pp.1-8
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• 2013

In this study, 120 cases of damage due to ground subsidence of city gas pipeline which is hanging on apartment outer wall were investigated. From the survey results, it was determined to be approximately 100m~200mm ground subsidence occurred and at severe damage, pipeline was cut and the gap was about 50mm between two cut pipeline. Device for measuring the amount of deformation of standing gas pipeline was designed and fabricated. And installed it on apartment outer wall for measuring the deformation due to ground subsidence, after 5 months measurement the amount of ground subsidence was measured to 1.3mm. Stress assessment was conducted based on results of ground subsidence occurred on standing gas pipeline.

• Korean Journal of Materials Research
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• v.9 no.7
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• pp.735-739
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• 1999

In this study we investigated stress development and shrinkage of thickness for a single $PbTiO_3$(PT) layer prepared by sol-gel processing. Changes of microhardness for multideposited PT layers with temperatures are also monitored to understand the densification of thin films. Single PT layer shrank rapidly from room temperature to$ 220^{\circ}C$ yielding 83% of total shrinkage observed up to $500^{\circ}C$. A tensile stress of ~75MPa developed in an as-spun layer, and increased steadily beyond $130^{\circ}C$ until it reaches the maximum value of 147MPa at $250^{\circ}C$. The significant decrease of tensile stress in the film beyond $370^{\circ}C$ indicates that thermal expansion mismatch between the film and the substrate dominates the stress behavior in this temperature range. Microhardness of the multideposited coatings also increased rapidly above $300^{\circ}C$ regardless of the pyrolysis temperatures used. Large amount of perovskite phase formed in multideposited coatings after $550^{\circ}C$ may be due partly to enhanced homogeneous nucleation in the thicker coating.

• Magazine of the Korean Society of Agricultural Engineers
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• v.34 no.3
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• pp.33-42
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• 1992

The shear strength of cohesionless Soils results from particle-to-particle friction and structural resistance by interlocking. And, the shear strength of soils is subjected to vary depending on the internal states and external condtions. If the volume change occurring in the soils and stress-strain relationships under the internal and external changes can accrurately he described, it is possible to predict the behaviors of soils. To accomplish these objectives a series of drained triaxial compression tests and isotropic compression test was performed on the Banwol sand at different relative densities ranging from 20% to 80% and different confining pressures ranging from 0.4kgf/cm$^2$ to l2kgf/cm$^2$. The results and main conclusions of the study are summarized as follows; 1.When the relative density or the confining pressure is increased, the maximum deviator stress is increased. The ratio of the maximum deviator stress and the confining pressure is linearly proportional to the relative density. 2.It is observed that the dilatancy depends not only upon its relative density but also the confining stress, and that the maximum deviator stress is obtained after the diatancy occurs. 3.The volume of sands undergoes initial contraction prior to the dilatancy occurred by strain softening. The dilatancy rate eventually approaches the critical state or a constant volume. 4.At lower strains, Poisson's ratio approaches a certain minimum value regadless of the state of materials. At larger strains, however, the ratio is increased as the relative density is increased. 5.It is observed that the modulus of elasticity is linearly proportional to the relative density and the pressure. 6.When the relative density is increased, the friction angle of sands is linearly increased. 7.When the relative density is increased, the expansion index and the compression index are linearly decreased, and the ratio of the two is about 1/3.

• Culinary science and hospitality research
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• v.17 no.2
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• pp.18-34
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• 2011

This research was conducted to analyze structural relationships comparatively between job stress, job burnout and turnover intention that school dietitians, school nutrition teachers and school foodservice employees have. The target group is school dietitians and nutrition teachers who work in 180 elementary, middle and high schools and foodservice employees in 50 schools. The survey is limited to the schools which operate school meals directly or indirectly in Seoul and Gyeonggi province. As a result, job demand and lack of rewards were found the most significant factors in the dimensions of job stress. The quantitative expansion of school meals is important; however, it is necessary to reduce stress in the work environment for dietitians, nutrition teachers and employees in school foodservices to perform their duties with dignity and satisfaction.

• Journal of Technologic Dentistry
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• v.35 no.4
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• pp.303-312
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• 2013

Purpose: In this research, non-linear three dimensional finite element models with contact elements were constructed. For the investigations of the distributions of contact stresses, 3 units fixed partial dentures model were studied, especially on the interface of the gold screw and cylinder, abutment screw. Methods: 3 types of models were constructed ; the basic fixed partial denture in molar region with 3 units and 3 implants, the intermediate pontic fixed partial denture model with 3 units and 2 implants, and the extension pontic fixed partial denture model with 3 units and 2 implants. For all types, the external loading due to chewing was simulated by applying $45^{\circ}$ linguo-buccal loading of 300 N to the medial crown. For the simulation of the clamping force which clinically occurs due to the torque, thermal expansion was provided to the cylinder as a preload. Results: Under 300 N concentrated loading to the medial crown, the maximum contact stress between abutment screw and gold screw was 86.85~175.86MPa without preload, while the maximum contact stress on the same area was 25.59~57.84MPa with preload. Conclusion: The preloading affected the outcomes of the finite element stress analysis. Reflecting the clinical conditions, the preloading conditions should be considered for other practical study utilizing FEA. For the study of the contact stresses and related motions, various conditions, such as frictional coefficient changes, gap between contact surfaces, were also varied and analyzed.

• Journal of the Korea Convergence Society
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• v.12 no.11
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• pp.391-401
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• 2021

The purpose of this study was to verify the moderating effects of the stress coping styles on the effects of internet addiction on the self-esteem of the 2030 generation during the Covid19 period. The 762 samples were selected through an online survey, and the collected data were conducted using the SPSS WIN26.0 program for frequency analysis, correlation analysis, and hierarchical regression analysis. As a result of the analysis, Internet addiction had a negative effect on self-esteem, and only seeking social support among the four sub-factors of stress response served as a moderator variable in the relationship between Internet addiction and self-esteem. Based on the results, the followings were suggested: expansion of research subjects regarding Internet addiction and interdisciplinary convergence study, providing universal provision of stress coping management programs, building a community at the local level, and discovery and reinforcing variables that offset the negative role of self-esteem of 2030 generations.