• Journal of Power System Engineering
• /
• v.15 no.6
• /
• pp.73-80
• /
• 2011

The experimental investigation focuses on an influence of artificial aging time in longitudinal butt welded Al 6013-T4 aluminum alloy on the fatigue crack growth resistance. The preferred welding processes for this alloy are frequently tungsten inert gas welding (TIG) process due to its comparatively easier applicability and better weldability than other gas metal arc welding. Fatigue crack growth tests were carried out on compact tension specimens (CT) in longitudinal butt TIG welded after T82 heat treatment was varied in three artificial aging times of 6 hours, 18 hours and 24 hours. Of the three artificial aging times, 24 hours of artificial aging time are offering better resistance against the growing fatigue cracks. The superior fatigue crack growth resistance preferred spatial variation of materials within each specimen in the Paris equation based on reliability theory and fatigue crack growth rate by crack length are found to be the reasons for superior fatigue resistance of 24 hours of artificial aging time was compared to other joints. The highest of crack propagation resistance occurs in artificial aging times of 24 hours due to the increase in grain size (fine grained microstructures).

• International Journal of Korean Welding Society
• /
• v.3 no.1
• /
• pp.39-44
• /
• 2003

The welded specimens were made by butt welding of the 2 wires of 50mm length using the pulsed YAG laser. The laser welded wires were tested for investigating the shape memory effect and the ability of super elasticity. The fatigue properties of the welded wires were investigated using the rotary bending fatigue tester specially designed for wires. Moreover, the effect of defocusing distance during laser welding on the static and fatigue properties was Investigated. The shape memory effect and super elasticity of the laser welded wires were approximately identical with that of base metal at the test temperature below 353K. However, the welded wires were broken within elastic limit at the test temperature above 353k. Under the cyclic bending loading conditions, the welded wires could be useful only below the elastic limit, while the base metal had sufficient fatigue life even the stress induced M-phase region. The fatigue strength of the welded wires was about half of that of the base metal. The deterioration of the static and fatigue properties in the welded wires was proven to be from the large difference of the transformation behavior between the base metal and welded part that is caused by vaporization of Ni-content at the welded part during the welding process. The defocusing distance below 3mm acted more largely on lowering the strength of the welded wires than that of 6mm or 8mm.

• The Journal of the Society of Korean Medicine Diagnostics
• /
• v.17 no.2
• /
• pp.122-130
• /
• 2013

Objectives This study investigated the relationship between exercise and health factors including vaso-aging degree, stress index, stress resistance, fatigue and activity of autonomic nerve system etc. Methods The subjects were 20,509 persons who had received health examination by Korean Medicine and submitted questionnaires about exercise history, for 8 months from March to November in 2011. The vaso-aging degree were measured by APG (Accelerated Photoplethysmograph). The stress index and resistance, fatigue and activity of autonomic nerve system were measured by HRV (Heart Rate Variability). We analyzed the relationship between exercise and various variables by chi-square test with SPSS ver. 19.0. Results Regarding the relationship between exercise and vaso-aging degree, stress index, stress resistance, fatigue and activity of autonomic nerve system, there were significant differences(p<0.05). Conculsions This study suggests that vaso-aging degree, stress index, stress resistance, fatigue and activity of autonomic nerve system are affected by exercise.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.34 no.9
• /
• pp.1201-1207
• /
• 2010

In this study, a fatigue testing system capable of performing load-controlled tension-tension tests for micro-specimens was developed by using an electro-magnetic actuator. Using this system, fatigue testing as well as tensile testing can be performed over a wide range of loading frequencies. Further, a new laser interferometric strain/displacement gage was used during fatigue testing to obtain high-resolution measurements of the cyclic deformation of thin films. Since the testing machine and the displacement gage are stable and show quick responses, the displacement can be measured instantaneously and continuously during fatigue testing, and high-resolution results can be obtained.

• The Journal of Korean Medicine
• /
• v.30 no.4
• /
• pp.28-36
• /
• 2009

Objectives: Fatigue is a prevalent symptom encompassing both acute and chronic manifestations. Most fatigue symptoms can be cured by taking a rest or removing underlying causes. However, chronic fatigue is frequently problematic due to its duration and effect on quality of life. There are no particularly effective therapies for chronic fatigue of unknown causes, and patients in Korea usually visit an Oriental clinic. This study aimed to analyze the current status of treatments and patients with chronic fatigue, and then map out of a strategy for development of generalized-treatments for chronic fatigue in Oriental Medicine. Methods: Clinical information related to chronic fatigue was selected from various different databases such as PubMed, KoreaMed, KStudy, DBPIA, OIM, and KOMS. Also, to understand current tendency of medical examination and treatment related with chronic fatigue, we requested Health Insurance Review & Assessment Service for clinical datum from 2003 to 2007. Results: The medical fees of National Health Insurance related with fatigue show an explosive year-on-year increase. On the other hand, it has been decreasing annually in the western medical fields. To take charge of clinical fields related with chronic fatigue by Oriental Medicine, we should make a unified diagnostic system. Then, we should also make standard evaluation tools and develop herbal drugs according to this unified diagnostic system. Conclusions: Fatigue-related symptoms will be a main target of Oriental medicine in the future. We expect that various studies related with chronic fatigue will be undertaken hereafter.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2003.11a
• /
• pp.396-401
• /
• 2003

For a realistic and reasonable determination of condition and status, assessment system should include load modeling for the loads acting on slab bridges due to traffic loads, evaluation system for fatigue, and determination of remaining service life. The purpose of the present study is to develop a realistic expert system which can estimate reasonably the fatigue and service life of slab bridges, based on the load models that are derived from the traffic loads.

• Journal of the Korean Society for Precision Engineering
• /
• v.25 no.8
• /
• pp.96-103
• /
• 2008

In this study, we performed the biomechanical analysis of cervical plate systems by using a computer simulation based on finite element method to derive reliable model by analysis of design variables and fatigue behavior. To simulate the cervical spine movement in-vivo state by surgery, we modeled the cervical plate system which consisted of screws, rings, rivets, and plate and Ultra High Molecular Weight Polyethylene (UHMWPE) Block. The experiment of cervical plate system followed the ASTM F1717 standards that covered the materials and methods for the static and fatigue testing. The result of computer simulation is compared with experimented test. We expected this study is to derive reliable results by analysis of design variables and fatigue behavior for developing a new model.

• 대한상한금궤의학회지
• /
• v.7 no.1
• /
• pp.107-113
• /
• 2015

Objective : This study aims to explain the effect of Buja-tang on Postherpetic Neuralgia with Chronic Fatigue Syndrome which a Soeum-byeong patient has. Methods : This is a case report on a female patient who has been suffering from Postherpetic Neuralgia with Chronic Fatigue Syndrome. According to Diagnostic system based on Shanghanlun provisions, Buja-tang was provided for one month. Results : After a series of Buja-tang treatments, the patient's symptoms and result improved. Conclusions : This case study show an effectiveness of using Buja-tang according to Diagnostic system based on Shanghanlun provisions on Postherpetic Neuralgia with Chronic Fatigue Syndrome.

• Proceedings of the KSME Conference
• /
• 2000.04a
• /
• pp.375-380
• /
• 2000

The purpose of this study is to verify the relations with the fatigue life and stress distribution on the screw thread for thoracic and lumbar spine. These screws are now developed for Korean in this research group. The fatigue life of single screw was found longer than that of up-left-screw, but shorter than that of up-right-screw. The fatigue life of screw used was associated with the angie between bending and thread direction. In the case of upper left and right screw were fractured in the region of one pitch and two pitch of the thread valley from the shank of pedicle screw, respectively.

• Proceedings of the Korean Powder Metallurgy Institute Conference
• /
• 2006.09a
• /
• pp.142-143
• /
• 2006

Recently, automotive engines have changed to the silent chain system in order to reduce noise and to improve reliability. High contact fatigue strength is needed for the sprockets of silent chain system. As a result, a high-contact-fatigue-strength P/M material was developed using the technology of surface rolling, which densifies the surface layer of sintered parts. It was established that the contact fatigue strength of the developed material was a great improvement over that of the conventionally used sintered material.