• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.8
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• pp.5654-5663
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• 2015

In the unsaturated soil, suction, the negative pore water pressure leads to increases of the yield stress and the plastic shear stiffness of the soil skeleton due to the growth in interparticle stress. Therefore, in this study, the stress-strain relationship based on cyclic elasto-plastic constitutive model extended for unsaturated soil considering the 1st and the 2nd yield functions was induced in order to account for these effects of suction under the dynamic loading condition such as the earthquake. Through the program code considering this relationship and the routine of the cyclic loading with the reversion of loading direction, the numerical simulation of the cyclic triaxial test under the unsaturated condition would be possible. It is expected that the results of this study possibly contribute to the accuracy improvement on the prediction of unsaturated soil behavior under the dynamic loading condition.

• Journal of the Ergonomics Society of Korea
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• v.31 no.1
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• pp.197-202
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• 2012

Objective: The aim of this study is to introduce activities for job stress management in shipbuilding industry. Background: Recently, workers are exposed many job stress like workload, interpersonal conflict while management condition of company changes day by day. Particularly, shipbuilding industry has poor environment which aggravating the stress to the workers. So managing job stress may be more important. Method: The method of this study is to investigate preventive actions of job stress in "S" shipbuilding company. Results: This study through case of "S" shipbuilding company introduce activities of prevention of job stress including identification of level of job stress, managing of psychological clinic, training of worker and manager. Conclusion: In order to manage the job stress in the workplace, 1) The total management system based on the concern of the management in the workplace has to be constructed. 2) Computerized system for operation of total management system has to be constructed. 3) New employees need training for Job Stress. Application: Through this case study, I hope to help prevention activities of job stress in the workplace.

• Journal of Korean Society of Steel Construction
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• v.25 no.3
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• pp.243-254
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• 2013

Internally Confined Hollow RC(ICH RC) column consisted of concrete, transverse reinforcement, longitudinal reinforcement, and inner tube. It had good strength and ductility by core concrete was become triaxial confining state with transverse reinforcement and inner tube. There were two confining stress as external confining stress and internal confining stress in an ICH RC column. While external confining stress was researched by former researchers, internal confining stress has not researched. In this paper, confining stress of both Hollow RC column and ICH RC column was investigated using FEA program. Relation between theoretical confining stress and internal confining stress was drawn by analysis results. Modified failure condition equations of inner tube were suggested to base on failure condition equations of inner tube by former researcher. When thickness of inner tube was calculated by modified equations, it could be economic because thickness of inner tube was reduced 50% compared with former researcher equations in order to same confining stress.

• Design & Manufacturing
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• v.11 no.2
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• pp.51-56
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• 2017

Nitinol, a shape memory alloy (SMA), is manufactured from titanium and nickel and it used in various fields such as electrical applications, micro sensors. It is also recommended as a material in medical for implant because it has excellent organic compatibility. Nitinol is intended to be inserted into the human body, products require a high-quality surface and low residual stress. To overcome this problems, explore electrolyte polishing (EP) is being explored that may be appropriate for use with nitinol. EP is a particularly useful machining method because, as a non contact machining method, it produces neither machining heat nor internal stress in the machined materials. Sandpaper polishing is also useful machining method because, as a contact machining method, it can easily good surface roughness in the machined materials. The electrolyte polishing (EP) process has an effect of improving the surface roughness as well as the film polishing process, but has a characteristic that the residual stress is hardly generated because the work hardened layer is not formed on the processed surface. The sandpaper polishing process has the effect of improving the surface roughness but the residual stress remains in the surface. We experimented with three conditions of polishing process. First condition is the conventional polishing. Second condition is the electrochemical polishing(EP). And Last condition is a mixing process with the conventional polishing and the EP. Surface roughness and residual stress of the nitinol before a polishing process were $0.474{\mu}mRa$, -45.38MPa. Surface roughness and residual stress of the nitinol after mixing process of the conventional polishing and the EP were $1.071{\mu}mRa$, -143.157MPa. Surface roughness and residual stress of the nitinol after conventional polishing were $0.385{\mu}mRa$ and -205.15MPa. Surface roughness and residual stress of sandpaper and EP nitinol were $1.071{\mu}mRa$, -143.157MPa. The result shows that the EP process is a residual stress free process that eliminates the residual stress on the surface while eliminating the deformed layer remaining on the surface through composite surface machining rather than single surface machining. The EP process can be used for biomaterials such as nitinol and be applied to polishing of wafers and various fields.

• Journal of the Korean GEO-environmental Society
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• v.19 no.12
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• pp.25-32
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• 2018

This paper investigates the effect of rock discontinuities on a shear stress wave that is induced by earthquake or blasting and provides the result of numerical parametric studies. The numerical tests of different conditions of rock and discontinuity have been carried out after confirming that the numerical approach is valid throughout a verification analysis from which the test results were compared with a theoretical solution. In-situ stress condition was considered as a rock condition and internal friction angle and cohesive value, which are the shear strength parameters, were considered as discontinuities condition. The joint inclination angle was also taken into account as a parameter. With the various conditions of different parameters, the test results showed that a shear stress wave propagating through a mass is highly influenced by the shear strength of discontinuities and the condition of joint inclination angle as well as in-situ stress. The study results indicate that when earthquake or blasting-induced dynamic loading propagates through a jointed rock mass or a stratified soil ground the effect of in-situ stress and discontinuities including a stratum boundary should be taken into account when evaluating the dynamic effect on nearby facilities and structures.

• Journal of Physiology & Pathology in Korean Medicine
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• v.18 no.2
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• pp.496-499
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• 2004

We have previously observed that Bambusae Caul is in Liquamen (BCL) stimulates the adipose conversion of 3T3-L1 cells and molecular chaperones were involved in the process of the assembly and replacement of laminin subunits in Bovine aortic endothelial cells(BAEC). Endothelial cells are exposed to continuous shear stress due to the blood flow. Heat shock protens(hsp) are a well-known stress response protein, namely, stress proteins. To investigate effects of BCL on the stress proteins induced by heating in endothelial cells, we have analyzed synthetic amounts of stress proteins in sodium dodecyl sulfate gel electrophoresis under reducing conditions. Under the condition of heating stress, BCL inhibited the synthesis of stress proteins in endothelial cells. These results suggest that BCL may have an important role for expression of stress proteins induced by heating in endothelial cells.

• International Journal of Reliability and Applications
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• v.17 no.1
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• pp.85-105
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• 2016

In this paper accelerated life testing is incorporated in quality control technique of acceptance sampling plan to induce early failures in high reliability products.Stress under accelerated condition can be applied in constant-stress, step-stress and progressive-stress or combination of such loadings. A ramp-stress results when stress is increased linearly (from zero) with time. In this paper optimum failure-censored ramp-stress accelerated life test sampling plan for log-logistic distribution has been formulated with cost considerations. The log-logistic distribution has been found appropriate for insulating materials. The optimal plans consist in finding optimum sample size, sample proportion allocated to each stress, and stress rate factor such that producer's and consumer's interests are safeguarded. Variance optimality criterion is used when expected cost per lot is not taken into consideration, and bilevel programming approach is used in cost optimization problems. The methods developed have been illustrated using some numerical examples, and sensitivity analyses carried out in the context of ramp-stress ALTSP based on variable SSP for proportion nonconforming.

• 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 Home Health Care Nursing
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• v.10 no.1
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• pp.34-40
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• 2003

Purpose: The purpose of this study was to investigate the job stress in home care nurses. Method: The subjects were 139 home care nurses of hospital in an urban cities. The data were collected from 26 Man to 27 June by self report adherence questionnaire. Job stress was measured using CHN-PWRSQ(Community Health Nurses Perceptions of Work-Related Stressors Questionnaire). Result: The average score of job stress was 60.8. There were significantly high levels of job stress in those who have less than 10 years office period, those who have less than 2000000 won monthly salary than in their counterparts. With regard to the level of job stress by item, 'driving long distance and traffic jam', 'risk of traffic accident', 'bad weather condition', 'uncooperative family members', and 'uncooperative client/patient' were higher than other items. The age and office period were negatively correlated with job stress. Conclusion: The average score of job stress was 60.8. 'driving long distance and traffic jam', 'risk of traffic accident', 'bad weather condition', 'uncooperative family members', and 'uncooperative client/patient' were higher than other items. The age and office period were negatively correlated with job stress.

• Biomedical Science Letters
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• v.11 no.2
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• pp.135-141
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• 2005

A Jopock (Jpk), a trans-acting factor associating with the position-specific regulatory element of murine Hoxa-7, has shown to have a toxicity to both prokaryotic and eukaryotic cells when overexpressed. Since Jpk protein harbors a transmembrane domain and a putative endoplasmic reticulum (ER)-retention signal at the N-terminus, a subcellular localization of the protein was analyzed after fusing it into the green fluorescent protein (GFP): Both N-term (Jpk-EGFP) and C-term tagged-Jpk (EGFP-Jpk) showed to be localized in the ER when analyzed under the fluorescence microscopy after staining the cells with ER- and MitoTracker. Since ER stress triggers the ER-stress mediated apoptosis to eliminate the damaged cells, we analyzed the expression pattern of Jpk under ER-stress condition. When MCF7 cells were treated with the ER-stress inducer such as DTT and EGTA, the expression of Jpk was upregulated at the transcriptional level like that of Grp78, a molecular chaperone well known to be overexpressed under ER-stress condition. In the presence of high concentration of ER-sterss inducer (10 mM), about 70 (DTT) to $95\%$ (EGTA) of cells died stronly expressing ($10\~12$ fold) Jpk. Whereas at the low concentration ($0.001\~1.0\;mM$) of the inducer, the expression of Jpk was increased about 2.5 (EGTA) to 5 fold (DTT), which is rather similar to those of ER chaperone protein Grp78. These results altogether indicate that the ER-stress upregulated the expression of Jpk and the excess stress induces the ER-stress induced apoptosis and the concomitant expression of Jpk.