• Journal of the Korean GEO-environmental Society
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• v.14 no.10
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• pp.17-27
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• 2013

This paper explores stress release induced by unloading in dry sand. A series of model tests were carried out to measure stresses developed in testing sand during loading and those released during unloading for different boundary conditions. It was found that stress in the sand increased linearly with applied load. At the onset of unloading, almost no stress release was observed. Significant stress release took place when the shear stress in the sand induced by unloading exceeded the frictional resistance and caused movement of sand particles. The initiation and the magnitude of stress release depend on the stress condition prior to unloading, the decrease of external load, and also the frictional resistance in sand. A new conceptual stress-release model was next developed based on the model test results by considering the fundamental frictional behavior of granular materials.

• Journal of Welding and Joining
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• v.21 no.1
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• pp.66-71
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• 2003

The release of residual stress by mechanical loading and unloading is often performed in the fabrication of box structure fur steel bridge. The proper degree of loading and unloading is significant at release method of residual stress by mechanical loading because that degree is changed by material and geometric shape of welded structure. Therefore, the simulation model that could exactly analyze the release of residual stress by mechanical loading is to be necessary. In this study, the non-linear behavior of weldments under external loading and unloading, such as the decrease and increase of structure stiffness, was investigated by monitoring of nominal stress and strain. Tensile loading and unloading test and the proper degree of stress relaxation was measured by sectioning technique using strain gauge. Analysis model that is indispensable for the effective application of MSR method was established on the basis of test and measurement result.

• Proceedings of the KWS Conference
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• 2002.10a
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• pp.372-377
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• 2002

Residual stress by welding should be reduced because that decreases the reliability on strength of welded structure. The reason is that the total stiffness of structure decreases by non-linear behavior of weldment under external load. The release of residual stress by mechanical loading and unloading is often performed in the fabrication of box structure for steel bridge. The proper degree of loading and unloading is significant at release method of residual stress by mechanical loading because that degree is changed by material and geometric shape of welded structure. Therefore, the simulation model that could exactly analyze the release of residual stress by mechanical loading is to be necessary. This simulation model should be established on the based of variable and accurate measurement data. In this study, the non-linear behavior of weldments under external loading and unloading, such as the decrease and increase of structure stiffness, was investigated by monitoring of nominal stress and strain. Tensile loading and unloading test under variable load was performed and the proper degree of stress relaxation was measured by sectioning technique using strain gauge.

• International Journal of Korean Welding Society
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• v.2 no.1
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• pp.40-44
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• 2002

Residual stress by welding should be reduced because that decreases the reliability on strength of welded structure. The reason is that the total stiffness of structure decreases by non-linear behavior of weldment under external load. The release of residual stress by mechanical loading and unloading is often performed in the fabrication of box structure for steel bridge. The proper degree of loading and unloading is significant at release method of residual stress by mechanical loading because that degree is changed by material and geometric shape of welded structure. Therefore, the simulation model that could exactly analyze the release of residual stress by mechanical loading is to be necessary. This simulation model should be established on the based of variable and accurate measurement data. In this study, the non-linear behavior of weldments under external loading and unloading, such as the decrease and increase of structure stiffness, was investigated by monitoring of nominal stress and strain. Tensile loading and unloading test under variable load was performed and the proper degree of stress relaxation was measured by sectioning technique using strain gauge.

• Journal of the Korean Geosynthetics Society
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• v.17 no.4
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• pp.141-155
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• 2018

Recently, the number of ground subsidence resulting from underground cavity has been increased. Accordingly, the importance of restoration of stress release zone around the underground cavity has been emphasized. The stress release zone is composed of low density soils having extremely low stiffness and degree of compaction, which can lead to additional cavity expansion and collapse of overlying ground. Therefore, in this study, the suitability of restoration method of underground cavity using expansive material for reinforcement of stress release zone around the cavity is verified. The basic physical properties and expansion characteristics of the expansive material were examined. The experiment equipment capable simulating of stress release zone was developed and is used to investigate the effect of expanding material on stress release zone. The stress release zone was simulated using the spring in numerical analysis. The factors of the volume ratio of the underground cavity to the expansion material, the degree of stress relaxation, and the shape of the cavity were varied in numerical simulations, and the behavior of stress release zone was analyzed based on the numerical analysis results. Analysis variables are factors that affect each other. Also, filling of underground cavity and capacity of restoration of stress release zone were confirmed when the expansive material was inserted into underground cavity.

• Journal of the East Asian Society of Dietary Life
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• v.15 no.6
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• pp.773-781
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• 2005

Menu-development is one of the important parts in restaurant business. Menu in restaurant has to be developed by customer's net which is the key for the success in restaurant management, The purpose of this study is to determine stress level, food intake, food habit, food preference of employees in certain companies and to develop proper menus for employees who are under high stress state. This study also determine whether the customers under stress will visit restaurant which provide stress-release-menu or not This study was conducted to people who live in Seoul and its adjunct area, including Gyunggi Province. The subjects were selected at random and the Questionnaires were sent to the subject by mail. The surveys included personal information, extent of stress, food habits related to the stress. The statistical tests were performed with SPSS computer software program. The male subjects were $44.9\%$ and females were $55.1\%$, aged between $30\~40$ years old. The percentages of no risk, borderline, and at risk, in the stress level of subjects, were 48.3, 16.5 and $35.2\%$, respectively. Most of the subjects, $61.8\%$, had normal food habit and $29.2\%$ had bad food Habits. The ideal costs of meals were $3,000\~5,000Won$ for breakfast$(57.3 \%)$, $5,000\~10,000Won$ for lunch$(54.7\%)$, and $10,000\~20,000Won$ for dinner$(38.2\%)$. Subjects under high stress answered 0 need a dietary supplementation for stress release. This study also showed that $92\%$ of the subjects under stress were willing to visit restaurants which have stress-release menus. In conclusion, adults who are under stress are shown to be interested in stress and nutrition management and they are willing to visit restaurants providing stress-release menus.

• Journal of International Academy of Physical Therapy Research
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• v.11 no.4
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• pp.2237-2243
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• 2020

Background: The myofascial release technique is known to be an effective technique for increasing posterior fascia flexibility in short hamstring syndrome (SHS) subjects. But therapeutic mechanism of myofascial relaxation remains unclear. Recently, the theory of autonomic nervous system domination has been raised, however, a proper study to test the theory has not been conducted. Objectives: To investigate whether the application of the myofascial release technique can induce changes in the autonomic nervous system and affect the secretion of stress hormones and myofascial relaxation. Design: Quasi-experimental study. Methods: Twenty-four subjects with SHS were randomly divided into two groups. In the experimental group, the suboccipital muscle inhibition (SMI) technique was applied to the subjects for 4 min in supine position, and in the control group, the subjects were lying in the supine position only. A forward flexion distance (FFD) was conducted, blood pressure, heart rate, and cortisol levels were measured before and after the intervention and 30 min after intervention to determine myofascial relaxation and stress hormone levels. The evaluation was conducted separately in blind by an evaluator. Results: A FFD decreased in the experimental group, no change in cortisol was observed. On the contrary, a decrease in cortisol appeared in the control group after 30 minutes. Conclusion: The myofascial release technique is an effective treatment to increase the range of motion through posterior superior myofascial chain, but there is no evidence that myofascial release technique can control the autonomic nervous system.

• Transactions of the Korean Society of Mechanical Engineers
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• v.19 no.7
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• pp.1590-1596
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• 1995

The energy release rates for a dynamically growing crack in orthotropic materials are expressed explicitly in terms of dynamic stress intensity factors. The stress functions suitable for the problem are found and the evaluation of the J-integral for the theoretical singular crack tip fields yields energy release rates. The present results are simpler than the existing ones and can be reduced to the well known solutions in special cases. Examples of extracting stress intensity factors from the finite element solution using the present results are given for the dynamically growing crack problem of orthotropic materials.

• Journal of Forest and Environmental Science
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• v.34 no.4
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• pp.338-351
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• 2018

This study was conducted in a long-term experimental forest in the central hardwoods region of southwestern Michigan to retrospectively examine the role of past forest management practices and climate on red oak (Quercus rubra L.) productivity. Initially, in 1971, plots within the experimental forest were treated separately with a clearcut and shelterwood regeneration harvest in an attempt to increase red oak regeneration. From 1987-1989, a new study was initiated within a portion of the clearcut and shelterwood plots to evaluate the effectiveness of additional oak crop tree release using mechanical and chemical applications. Cumulative diameter and mortality rates of 719 red oaks were monitored across the four silvicultural treatments: Clearcut-A (clearcut without additional release treatment), Clearcut-B (clearcut with additional release treatment), Shelterwood-A (shelterwood without additional release), and Shelterwood-B (shelterwood with additional release) plus an untreated control. Increment cores were obtained from red oak trees and neighboring competitor species. Tree-ring analyses (dendrochronology) were applied to examine the effect of these silvicultural treatments and climatic factors (temperature and precipitation) on red oak productivity. The results indicated that crop tree release following a clearcut or shelterwood harvest reduced mortality rates and thus increased survival of red oak. Red oak in control plots or plots only receiving the initial regeneration harvesting treatment and no additional competition release were negatively affected by climatic stress, which included summer moisture stress. In contrast, red oak in plots that received the competition release treatment from shade tolerant tree species not only had higher tree level productivity (i.e., tree basal area) and lower mortality rates, but were also relatively more resilient to climatic stress by showing limited or no associations between climate and growth.

• Journal of the Korean Society for Precision Engineering
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• v.20 no.7
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• pp.193-200
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• 2003

The energy release rate for an interface crack in pseudo-isotropic dissimilar materials was obtained by the eigenfunction expansion method using the two-term William's type complex stress function. The complex stress function for pseudo-isotropic materials must be different from that for anisotropic materials. The energy release rate for an interface crack in pseudo-isotropic dissimilar materials was analyzed numerically by RWCIM. The results obtained were verified by comparing the other worker's results and discussed.