• Journal of Auto-vehicle Safety Association
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• v.4 no.1
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• pp.18-22
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• 2012

The US-NCAP was rated by the head and chest injury, but the new US-NCAP requires various dummy injury parts such as head, neck, chest, and femur. So, new restraint systems are needed. Particularly, the knee bolster must meet both unbelted and belted test condition requirements. This paper analyzed the dummy response of both test condition and suggested a knee bolster F-D requirement as well as a new knee bolster structure.

• Journal of Welding and Joining
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• v.19 no.6
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• pp.658-663
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• 2001

Residual stress caused in the weldments with high restraint force are often during welding observed in the weldments of large size nozzles or radial tanks. The reason is that quantitative analysis about thermal stresses during welding is lack for this weldments. To verify FEM theory, the temperature was measured with thermocouple in a real time in this paper. Also analysis of the thermal stress for welding condition is performed by ABAQUS program package on various welding condition in STS butt welding.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2000.04b
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• pp.141-149
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• 2000

This study performs the elastic and viscoelastic analysis of composite continuous beams with flexible shear connectors. Due to creep and shrinkage of the concrete part, the stress redistribution between the concrete slab and steel beam, and the evolution of the redundant restraint reaction occur with time. Using the equation of equilibrium, internal and external compatibility condition, and constitutive relationships, mathematical formulations are formulated. The solution is obtained by means of numerical step-by-step techniques and the finite difference method. Numerical parametric studies are performed to evaluate the stress redistribution, and the evolution of the redundant restraint reaction. The parameters include the stiffness and spacing of shear connectors, the age of concrete at loading, and the relative humidity.

• Journal of the korean Society of Automotive Engineers
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• v.12 no.2
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• pp.59-70
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• 1990

Crack of breaking toughness of most Ceramics material is 1-5MPa .root.m but that of Zirconia Ceramics is improved to be 6-8MPa .root.m and its development of machining difficult-to-machine material is on the rise as urgent subject. For general Zirconia Ceramics machining, diamond grinding wheel is generally used by selecting an appropriate one and establishing grinding condition but due to such limitations as economics, grinding efficiency and machining geometry, great interest in machining method being used for diamond tool is emphasized. But it is reported that diamond tool is oxidized by cutting heat in the air and is graphitized in vacuum, which causes bad effects on tool life. In this study, to restraint cutting heat the internal side of tool is cooled, and restraint low temperature cooling system and being experimented. Further, the machinability of diamond tool for Zirconia Ceramics machining is analyzed with respect to tool wear and stress.

• The Journal of Engineering Geology
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• v.8 no.3
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• pp.215-224
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• 1998

In this study, total strain was measured by LVDTs and local strains on the surface of specimens were measured by strain gauges. And axi-symmetrically elastoplastic FEM analyses was carried out for cylindrical specimens. Considering the influence of the restraint induced by the loading platen, in the case of H/D=1, the strain distribution on the side of a specimen is obviously affected by the condition of platen contact. Furthermore, it is clear that the larger H/D ratio becomes, the smaller the influence to the strain distribution is. For the smooth contact condition, the strain on the side is not influenced by the stiffness of the specimen, the shape and the scale effect, the strain distribution coincides with the nominal total strain. Whereas, in the case of rough contact condition, the strain distribution is remarkably affected. It is made clear that strain responses of hard rock specimens may more sensitive than these of soft rock specimens as a results of interaction between loading platens and specimen and the uniaxial strength of specimens may strongly depends on this interaction and stress-strain relation is affected by the contact condition.

• Journal of Oral Medicine and Pain
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• v.32 no.1
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• pp.57-67
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• 2007

In currently, stress diseases are increased that present several sign and symptoms. Under stress condition, there are dry mouth, burning mouth syndrome, oral mucosa diseases and halitosis more frequently. Changing of salivary proportion is checked in almost patients with changing of function and structure in salivary gland. This study purpose are what effect stress does on salivary gland, and a-amylase on salivary gland. This study was resulted that 1. Under restraint stress, acinar cells are vacuolization and changing of intercellular spaces are separated, and peripheral tissues of duct are changed 2. Acinar cells were shrunk after 3 hours under restraint stress, intercellular space was separated after 6hours, peripheral tissues of duct started to change after 72 hours, and acinar cells and peripheral tissues of duct were all severely changed after 168hours. 3. In immunohistochemical study, amylase reaction was showed partially and irregularly after 3 hours, was getting little milder after 6 hours. And amylase reaction was gradually increased from the time of 12 hours after experiment up to the time of 48 hours after experiment. But after 168 hours, amylase appearance was diminished. According this result, emotional stress can change of salivary gland structure, and amylase secretion, the important digestive enzyme from salivary gland is changed and it is supposed to make digestive disorder and to make halitosis efficiency. So, we need to study about secretion of amylase.

• Journal of Oral Medicine and Pain
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• v.33 no.3
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• pp.247-256
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• 2008

The belief that stress leads to illness has a long history. A number of the orofacial disease are also closely associated with stress. Despite research in the relationship of stress and the orofacial diseases leading to statistically significant correlations, the pathology remains vague. In the present study, the expression of clusterin, a stress protein responsible for antiapoptosis and cytoprotection, under restraint stress condition was observed in the submandibular gland, one of the major salivary glands. Sprague-Dawley rats were divided into 2 groups: normal group and restraint stress group. The rats of restraint stress group were placed in the stress cages and then sacrificed at day 0, 3 and 5 day of the experiment. After that, the submandibular glands of all the rats were excised immediately. The levels of clusterin proteins and mRNA in the tissues were measured by immunohistochemistry and Northern blot analyses, respectively. The results were as follows: 1. In the immunohistochemistry, clusterin protein was detected only immediately after the application of restraint stress. 2. In the restraint stress group, at day 3 and 5, histologically apoptosis was induced with karyorrhectic and pyknotic changes. 3. By the restraint stress, acinic cells were destructed earlier than ductal cells. 4. In the Northern blot, mRNA of clusterin was expressed only immediately after the application of restraint stress. The overall results suggest that as an early response to stress, clusterin is expressed in the glands to protect the glandular cells from the stress. But if stress is so strong and prolonged that it can exceed the stress adaptability of the cells, then the cells may undergo apoptosis instead of producing clusterin. An Epidemiologic Study of Symptoms of Temporomandibular Disorders in Korean College Students.

• Journal of the Korea Concrete Institute
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• v.22 no.1
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• pp.69-76
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• 2010

The majority of research that has been performed on cracking potential of concrete by shrinkage has assumed that concrete acts as a homogeneous material. However, with this approach, it is not able to evaluate the micro-cracking behavior in concrete due to autogenous shrinkage under unrestrained boundary condition (free boundary condition) nor to understand the cracking behavior properly because of the heterogeneous nature of concrete. To better understand the micro-cracking behavior of concrete induced by autogenous shrinkage, series of experiments were performed measuring the length change and acoustic emission energy. As an analytical approach, this research uses an object oriented finite element analysis code (OOF code) to simulate the behavior of the concrete on a meso-scale. The concrete images used in the simulations were directly obtained from mortar samples. From the experiments and simulation results, it was able to better understand the micro-cracking behaviour of concrete due to shrinking of paste phase and internal restraint by aggregates.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2018.11a
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• pp.27-28
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• 2018

In this study, water vapor pressure and restrained stress were evaluated by ring-type restrained condition for compressive strength 60 and 80MPa concrete. Experimental results show that the 80MPa concrete has higher water vapor pressure and restraint stress than the 60MPa concrete, resulting in spalling occurrence. It is because, the higher the compressive strength of the concrete, the more dense the internal structure is formed.

• Proceedings of the Korea Concrete Institute Conference
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• 1997.10a
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• pp.125-130
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• 1997

This study is to investigate properties of relationship between the heat of hydration of several type cements and the temperature of concrete in restraint condition. As the results, the heat of hydration is largely affected by the temperature of cementious materials. However, the heat of hydration of cement and temperature rise of concrete is differently resulted in the content of cement.