• Korean Journal of Head & Neck Oncology
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• v.27 no.1
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• pp.47-53
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• 2011

Purpose : Concurrent chemoradiotherapy(CCRT) with 3 weekly cisplatin is the standard treatment of locally advanced head and neck cancer(HNC). The aim is to evaluate the efficacy and toxicities of low-dose weekly cisplatin-based CCRT, which was devised to reduce the toxicity of CCRT. Method : We retrospectively analyzed HNC patients who received low-dose weekly cisplatin-based CCRT between 2008 and 2010. Cisplatin 35mg/$m^2$ was weekly given to all patients during radiotherapy. The efficacy was evaluated by the degree of clinical response, treatment failure and survival. The toxicity was evaluated by hematologic toxicities and oral mucositis. Results : A total of 27 patients were analyzed and median age was 59(range 31-81). The ratio of administered dose of radiotherapy and cisplatin to planned dose were 0.98 and 0.93, respectively. Complete remission and partial remission were 73% and 23%, respectively. Treatment failure was observed in 8(30%) patients. 1-year survival rate and 1-year disease free survival rate were 82% and 59%, respectively. Overall survival and progression-free survival did not reach median time. Grade 3/4 anemia, neutropenia, thrombocytopenia and oral mucositis were observed in 11%, 19%, 7% and 32% of patients, respectively. In terms of administered cycles, however, only 1-3% of grade 3/4 hematologic toxicities occurred among total 190 cycles. Severe oral mucositis were statistically associated with old age(p=0.003). Treatment failure had no statistical relation with age, pathology, primary site and stage. Conclusion : Low-dose weekly cisplatin-based CCRT seemed to deliver enough dose of cisplatin and to show low drop-out rate and good efficacy with low hematologic toxicities.

• Clinical and Experimental Reproductive Medicine
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• v.35 no.3
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• pp.213-221
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• 2008

Objective: To evaluate predictor of IVF outcomes following single embryo transfer in patients with decreased ovarian reserve. Methods: A retrospective review was performed in 919 IVF cycles with elevated basal serum FSH (${\geq}12\;mIU/mL$), the number of retrieved oocytes ${\geq}4$ and serum $E_2$ concentration on hCG day <500 pg/ml between Jan. 1996 and Dec. 2006. Two hundred thirty five IVF cycles following single embryo transfer were included. Pregnancy rates and live birth rates was evaluated according to maternal age, serum $E_2$ on hCG day, basal FSH level, the number of blastomere on day 3 ET, stimulation protocol, the number of cycles of ET. Statistical analysis was used SPSS 12.0 program. Results: OPU cancellation rates were 25.6% (235 cycles), OPU failure rates were 18.5% (170 cycles), embryo transfer cancellation rates were 14.0% (129 cycles). Pregnancy rates following single embryo transfer was 8.1% (19 cycles) and live birth rates was 4.7% (11 cycles). Pregnancy rates and live birth rates of women under 35 years old was statistically higher than those of women above 35 years old (20% vs. 3.5% (p<0.0001), 12.3% vs. 1.8%, (p=0.002)). There was no difference in basal FSH, serum $E_2$ on hCG day, and the number of blastomere on ET, and stimulation protocol. Cumulative pregnancy rates according to the number of cycles of ET were $1^{st}$ 8.1%, $2^{nd}$ 9.2%, $3^{rd}$ 9.7%, $4^{th}$ 9.0%, and $5^{th}$ 9.5%. Conclusion: Pregnancy rates and live birth rates of IVF-ET cycles following single embryo transfer in patients with decreased ovarian reserve are statistically increased in women under 35 yrs old. There is no difference in cumulative pregnancy rates. These data may be helpful for counseling women with decreased ovarian reserve in attempting IVF with their own eggs or when choosing donor oocytes.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.12 no.1
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• pp.58-64
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• 2003

A mechanical press joining was investigated in ender for joining A1-5052 sheets for automobile body weight reduction. Static tensile and fatigue tests were conducted using tensile-shear specimens for evaluation of fatigue strength of the joint. During Tox joining process for A1-5052 plates, using the current sheet thickness and punch diameter, the optimal applied punching force was found to be 32 kN under the current joining condition. For the static tensile-shear experiment results, the fracture mode is classified into interface fracture mode, in which the neck area fractured due to influence of neck thickness, and pull-out fracture mode due to influence of plastic deformation of the joining area. And, during fatigue tests for the A1-5052 tensile shear specimens, interface failure mode occurred in the region of low cycle. The fatigue endurance limit approached to 6 percents of the maximum applied load, considering fatigue lifetime of $2.5\times10^6$ cycles.

• Restorative Dentistry and Endodontics
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• v.42 no.1
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• pp.34-38
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• 2017

Objectives: The aim of this study was to evaluate the cyclic fatigue resistance of the ProTaper Universal D1 file (Dentsply Maillefer) under continuous and adaptive motion. Materials and Methods: Forty ProTaper Universal D1 files were included in this study. The cyclic fatigue tests were performed using a dynamic cyclic fatigue testing device, which had an artificial stainless steel canal with a $60^{\circ}$ angle of curvature and a 5 mm radius of curvature. The files were randomly divided into two groups (Group 1, Rotary motion; Group 2, Adaptive motion). The time to failure of the files were recorded in seconds. The number of cycles to failure (NCF) was calculated for each group. The data were statistically analyzed using Student's t-test. The statistical significant level was set at p < 0.05. Results: The cyclic fatigue resistance of the adaptive motion group was significantly higher than the rotary motion group (p < 0.05). Conclusion: Within the limitations of the present study, the 'Adaptive motion' significantly increased the resistance of the ProTaper Universal D1 file to cyclic facture.

• Journal of the Earthquake Engineering Society of Korea
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• v.6 no.4
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• pp.39-49
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• 2002

In this paper, the characteristics of RB(rubber bearing) were studied by various prototype tests on RB with low hardness rubber. The characteristics of RB were tested on displacements, repeated cycles, frequencies, vertical pressures, temperature, vertical stiffness and the capability of shear deformation. The prototype test showed that the displacement and vertical pressures were the most governing factors influencing on characteristics of RB. The effective stiffness and equivalent damping of RB showed small increment in high frequency range. After the repeated cyclic test with 50's cycles, the effective stiffness and equivalent damping of RB were almost constant compared with those of the 1st cycles due to low hysteretic damping. The shear modulus of RB was reduced after large deformation, and this value of RB was partly recovered after 40 days. Finally, the shear failure test of RB was conducted, the prototype was failed over 490% of shear strain, and real size RB was failed over 430% of shear strain.

• Radiation Oncology Journal
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• v.8 no.2
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• pp.255-260
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• 1990

From April 1985 to September 1989, 26 patients with stage I and II non-Hodgkin's lymphoma of unfavorable histology localized in head and neck region were treated with combined modality (combination chemotherapy plus radiotherapy) at the Department of Therapeutic Radiology in Kyungpook National University Hospital. Of the 26 patients, 23 showed complete response and 3 partial response. Between these two groups there were no statistical differences according to the variables. Three-year survival and disease-free survival rate were $62.4{\%}$ and $65.2{\%}$, respectively. Unilateral involvement of neck node (p<0.05), radiation dose over 5000 cGy (p<0.01), and 6 or more cycles chemotherapy (p=0.06) had a favorable effect on 3-year survival rate. There were 8 recurrences including 3 partial responders, 1 local failure, 1 distant failure, 1 contiguous failure, and 2 simultaneous local and distant failure. It could be suggested that combined modality treatment might be necessary for the treatment of stage I and II Non-Hodgkin's lymphoma of unfavorable histology.

• Journal of Biomedical Engineering Research
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• v.19 no.4
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• pp.393-401
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• 1998

Based on clinical observations, it is suspected that the bone-tendon origin is the site where piratical failure, leading to pathophysiological changes in the humeral epicondyle after repetitive loading, is initiated Mechanical properties and failure patterns of the common extensor and flexor tendons of the humeral epicondyle under static and repetitive loading have not been well documented. Our goal was to determine mechanical properties of failure strength and strain changes, to correlate strain changes and the number of cyclic repetitions, and to identify the failure pattern of bone-tendon specimens of common extensor and flexor tendons of the humeral epicondyle. Mechnaical properties of human cadaver bone-tendon specimens of the common extensor and flexor tendons of the humeral epicondyle were tested under two different loading rates. No statistically significant difference in ultimate tensile strength was found between male and female specimens or between slow (10 mm/sec) and fast elongation (100 mm/sec) rates. However, a statistically significant difference in ultimate tensile strength between the common extensor (1190.0 N/$cm^2{\pm}$388.8) and flexor 1922.0 N/$cm^2{\pm}$764.4)tendons was found (p<0.05). When loads of 25%, 33%, and 41% of the ultimate tensile strength of their contralateral sides were applied, the number of cycles required to reach 24% strain change for the common extersor and flexor tendons were approximately 8,893, 1,907, and 410, respectively. The relationship between cycles and loads was correlated ($R^2$=0.46) Histological observation showed that complete or partial failure after tensile or cyclic loadings occurred at the transitional zone, which is the uncalcified fibrocartilage zone between tendon and bone of the humeral epicondyle. Sequential histological sections revealed that failure initiated at the upper, medial aspect of the extensor carpi radialis brevis tendon origin. Biomechanical and hstological data obtained in this study indicated that the uncalcified fibrocartilage zone at the bone-tendon origin of the common extensor and flexor tendons is the weak anatomical structure of the humeral epicondyle.

• Journal of the Korea institute for structural maintenance and inspection
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• v.18 no.2
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• pp.54-63
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• 2014

Corrugated steel plate structure, which is built by assembling corrugated steel plate segments with bolts on site and filling the surroundings with quality soil, is widely used for buried structures as a eco-corridors, small bridges, and closed conduits. This experimental study is dealt with the static and fatigue performance of bolt connected corrugated steel plates under flexural loading. The experimental variables to verify the fatigue performance are bolt diameters and detailing of connection such as washer and the corrugation dimension of specimens has a $400{\times}150$ mm. The experimental ultimate strength of specimens under static loading was higher than the theoretical strength and all specimen failed by a bearing and tearing failure of bolt hole of upper plate. Therefore, a fatigue tests of specimens had 6.0mm and 7.0mm thickness was conducted in which the load range was up to 209kN and 516kN, respectively. From the fatigue test, failure patterns are changed from plate bearing and tearing which is a typical failure pattern of static failure to a bearing failure of plate and shear failure of bolt, and experimental fatigue limit at $2{\times}10^6$cycles is about 85MPa.

• Journal of the Korean Society for Heat Treatment
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• v.19 no.3
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• pp.163-169
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• 2006

Fretting is a kind of surface degradation mechanism observed in mechanical components and structures. The fretting damage decreases into 50-70% of the plain fatigue strength. The connecting rod for automobile has been used in special environments and various loading conditions. Failure of connecting rod in automotive engine may cause catastrophic situation. In this study, we investigated the fatigue characteristic of connecting rod material for an automobile. Fatigue life is defined as the number of cyclic stress to failure by regular cyclic stress. Fatigue life of C70S6 specimen was obtained from 134,000 to 147,000 cycles. Fatigue limit showed 432MPa by normal fatigue test. The other hands, it was 96MPa in the case of fretting fatigue test. It was extremely lower than that of a normal fatigue test. From observation of fracture surface, it was confirmed that the fatigue crack was initiated at the boundary of a specimen and bridge pad.

• Advances in materials Research
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• v.8 no.1
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• pp.11-24
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• 2019

This paper presents a review study for energy-efficient gas turbines (GTs) with cycles which contributes significantly towards sustainable usage. Nonetheless, these progressive engines, operative at turbine inlet temperatures as high as $1600^{\circ}C$, require the employment of highly creep resistant materials for use in hotter section components of gas turbines like combustion chamber and blades. However, the gas turbine obtain its driving power by utilizing the energy of treated gases and air which is at piercing temperature and pushing by expanding through the several rings of steady and vibratory blades. Since the turbine blades works at very high temperature and pressure, high stress concentration are observed on the blades. With the increasing demand of service, to provide adequate efficiency and power within the optimized level, turbine blades are to be made of those materials which can withstand high thermal and working load condition for longer cycle time. This paper depicts the recent developments in the field of implementing the best suited materials for the GTs, selection of proper Thermal Barrier Coating (TBC), fracture analysis and experiments on failed or used turbine blades and several other designing and operating factors which are effecting the blade life and efficiency. It is revealed that Nickel based Superalloys were promising, Cast Iron with Zirconium and Pt-Al coatings are used as best TBC material, material defects are the foremost and prominent reason for blade failure.