• Journal of the Korean Society for Precision Engineering
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• v.15 no.4
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• pp.51-57
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• 1998

It is common to assume identical allowable safety factors in static strength defined by mean stress and in fatigue, defined by stress amplitude. Under the load with asymmetrical cycles the safety factor is not the same. In this paper, with the consideration of unequal allowable safety (actors a general method for estimating fatigue reliability of a machine element under a combined state of stress is derived based on the theory proposed by Prof. Kececioglu and a normal distribution. The calculation of fatigue reliability fur limited life is discussed with example.

• Korean Journal of Computational Design and Engineering
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• v.5 no.2
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• pp.122-126
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• 2000

A major mechanical problem with total hip replacement is the loosening of the femoral component. The loss of proximal support, with firm fixation distally, has been thought to be a major caused of fatigue failure of femoral stems. While many causes have been proposed, the most frequently suggested cause of the calcar resorption is the disuse atrophy of the cortex of the calcar due to the stress shielding of the proximal bone by the metal femoral stem. In this research, the new-designed stem(modified collar stem) was considered which made a hole inside stem and had a 3 mm thickness. Using the 3-dimensional finite element methods, the common collar stem and the modified colla stem was modeled and analysed. Also, the two models was compared. The results showed that the modified collar stem decreased the stress-shielding and it made a effective load transfer at the entire femoral region.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2006.04a
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• pp.849-856
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• 2006

This paper is to examine the applicability of ordinary Kriging interpolation(OK) to the p-adaptivity of the finite element analysis that is based on variogram. In the p-refinement, the analytical domain has to be refined automatically to obtain an acceptable level of accuracy by increasing the p-level non-uniformly or selectively. In case of non-uniform p-distribution, the continuity between elements with different polynomial orders is achieved by assigning zero higher-order derivatives associated with the edge in common with the lower-order derivatives. It is demonstrated that the validity of the proposed approach by analyzing results for stress singularity problem.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1998.10a
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• pp.306-313
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• 1998

Contrary to reinforced concrete frames, the beams or girders found in actual steel frames are neither hinged nor fixed at their ends. Instead, they are usually restrained by the columns to which they are attached. Here in this paper, common finite element program for plane frame stress analysis is improved by including the effect of partial fixities of the girder ends. To include the effect of partial fixities of the girder ends, Kim's modified slope-deflection equation is adopted. The stress analysis results obtained by this proposed method are then compared with Kim's example. Finally, method of choosing the most economic girder section for a multi-story frame is suggested through the examples.

• Transactions of Materials Processing
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• v.22 no.4
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• pp.216-222
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• 2013

Solid polymers exhibit rate-dependent deformation behavior such as nonlinear strain rate sensitivity and stress relaxation like metallic materials. Despite the different microstructures of polymeric and metallic materials, they have common properties with respect to inelastic deformation. Unlike most metallic materials, solid polymers and shape memory alloys (SMAs) exhibit highly nonlinear stress-strain behavior upon unloading. The present work employs the viscoplasticity theory [K. Ho, 2011, Trans. Mater. Process. 20, 350-356] developed for the pseudoelastic behavior of SMAs, which is based on unified state variable theory for the rate-dependent inelastic deformation behavior of typical metallic materials, to depict the curved unloading behavior of polyphenylene oxide (PPO). The constitutive equations are characterized by the evolution laws of two state variables that are related to the elastic modulus and the back stress. The simulation results are compared with the experimental data obtained by Krempl and Khan [2003, Int. J. Plasticity 19, 1069-1095].

• Anxiety and mood
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• v.13 no.1
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• pp.1-9
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• 2017

We reviewed the scientific literature on psychological effects of Chemical, Biological, Radiological, Nuclear, Explosive (CBRNE) disaster, which is one of the biggest threat to modern society. CBRNE disaster has the potential to cause specific physical symptoms and psychological distress in victims ; moreover, various toxic symptoms and carcinogenesis/mutation would be an important issue. Bioterrorism can cause localized outbreaks of infectious disease or pandemic disaster. Somatization as well as posttraumatic stress symptoms and depression are the characteristic psychological symptoms in CBRNE disaster's victims. CBRNE disasters could lead to large-scale public fear and social chaos due to the difficulties involved in verifying the extent of exposure and unfamiliar area to the common people. In the evacuation process, problems associated with adjustment and conflict between victims and residents should be considered.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.26 no.1
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• pp.85-92
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• 2000

Common dental procedures(dental extraction & minor operation) are potentially stress-inducing in many patients, especially medically compromised patients. The body's response to dental stress involves the cardiovascular system(an increase in cardiovascular workload), the respiratory organ and the endocrine system(change in metabolism). To minimize the stress to the medical risk patient, the stress reduction protocol was established. The obtained contents were as follows: (1) Recognize the patient's degree of medical risk (2) Complete medical consultation before dental therapy (3) Schedule the patient's appointment in the morning (4) Monitor and record preoperative and postoperative vital signs (5) Use psychosedation during therapy (6) Use adequate pain control during therapy (7) Short length of appointment : do not exceed the patient's limits of tolerance (8) Follow up with postoperative pain/anxiety control (9) Telephone the higher medical risk patient later on the same day that treatment was given Though the stress reduction protocol above was applied to the dental extraction in medically compromised patients with the advanced infected teeth, the final responsibility for the complications(syncope, bleeding & infection, etc.) in a patient rests with the dentist who ultimately treats him. For the prevention of postextraction complications & poor prognosis, the authors treated the advanced infected teeth with the pulp extirpation, opening drainage through the canal and complete occlusal reduction. The final extraction and wound closure were then done after $1{\sim}2$ weeks. The final prognosis was comfortable without common complications.

• Journal of Life Science
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• v.32 no.10
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• pp.771-777
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• 2022

Dopaminergic (DA) cell death in Parkinson's disease (PD) has been attributed to multiple, distinct genetic and environmental factors. In rare familial PD loss of parkin function mutations play a key role in nigral DA neuron-specific pathogenesis primarily via endoplasmic reticulum (ER) stress. In more prevalent sporadic PD, environmental exposure to pesticides has a significant epidemiological role. However, it is largely unknown how environmental exposure to xenobiotics is etiologically linked with the known etiology in familial PD. In the present study biochemical evidence for a common pathogenic mechanism between sporadic and familial PD has been identified employing the recently characterized mesencephalic DA cell line, N27-A. Dieldrin, an organochlorine pesticide epidemiologically implicated in sporadic PD, induced the markers of ER stress response such as a chaperone BiP/Grp78, heme oxygenase-1 and especially, parkin. Accordingly, dieldrin activated the ER resident Caspase-12, a mediator of ER stress-specific apoptosis, during cell death of N27-A cells. Of great interest the dieldrin-induced DA neuronal cell death was synergistically rescued by the overexpression of ER resident neuroprotective proteins, parkin and Bcl-2. The present findings implicate that accumulation of ER stress could be one of common pathogenic mechanisms in idiopathic and familial PD, and some ER proteins, such as parkin and Bcl-2 may effectively attenuate ER stress-mediated N27-A DA cell death.

• The Journal of the Society of Korean Medicine Diagnostics
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• v.22 no.1
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• pp.11-18
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• 2018

Objectives The incidence of degenerative diseases is increasing as society ages, and this increased the economic burden on society. Oxidative stress was also under suspicion as one of the causes. Recent studies have found that Curcuma longa Rhizoma had antioxidant, anti-inflammatory, antimutagenic, and anticancer effects. Through this study, we figure out trends in Curcuma longa Rhizoma research and evaluate the therapeutic potential of Curcuma longa Rhizoma for dementia. Methods The search was made using domestic and international internet search sites. "Naver academic," "Google scholar," "Korea institute of oriental medicine (KIOM OASIS)," "Korean traditional knowledge portal (KTKP)," "Library of Congress," "Research information sharing service (RISS)," "National Digital Science Links (NDSL)," and "Pub med" are used to search. The searched for words were "turmeric," "Curcuma longa Rhizoma," "antioxidant," and "nerve regeneration." Results It could be seen that a lot of research done on Curcuma longa recently. In previous studies, the most common research disease was cancer. In previous studies, the most common effects of Curcuma longa was antioxidant and anticancer. Curcumin, Vitamin B1, and various essential oils were the functional components of Curcuma longa Rhizoma. Curcuma longa Rhizoma performs DPPH radical scavenging activity and ABTS radical cation decolorization activity; it inhibits NO and iNOS. Conclusion The destruction of nerve cells due to oxidative stress is a cause of dementia. Curcuma longa Rhizoma have antioxidant effects. Therefore, we believed that it is an effective treatment for dementia. Various studies will be made on Curcuma longa Rhizoma.

• Journal of Powder Materials
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• v.25 no.6
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• pp.507-513
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• 2018

This study investigates the viability of using a Na-ion battery with a tin(Sn) anode to mitigate the vulnerability caused by volume changes during discharge and charge cycling. In general, the volume changes of carbon material do not cause any instability during intercalation into its layer structure. Sn has a high theoretical capacity of $847mAh\;g^{-1}$. However, it expands dramatically in the discharge process by alloying Na-Sn, placing the electrode under massive internal stress, and particularly straining the binder over the elastic limit. The repeating strain results in loss of active material and its electric contact, as well as capacity decrease. This paper expands the scope of fabrication of Na-ion batteries with Sn by fabricating the binder as an auxetic structure with a unique feature: a negative Poisson ratio (NPR), which increases the resistance to internal stress in the Na-Sn alloying/de-alloying processes. Electrochemical tests and micrograph images of auxetic and common binders are used to compare dimensional and structural differences. Results show that the capacity of an auxetic-structured Sn electrode is much larger than that of a Sn electrode with a common-structured binder. Furthermore, using an auxetic structured Sn electrode, stability in discharge and charge cycling is obtained.