• Corrosion Science and Technology
• /
• v.4 no.4
• /
• pp.155-163
• /
• 2005

Heavy duty coating are required to have minimum durable period of 15 years under average usage environment because these paints are coated with purpose of anti-corrosion, antifouling, plastering etc. Onto steel structures constructed upon land and sea and other ferrous structures of electric power generation plants, electricity transmission towers, large structures of various plants, etc. Therefore we tried to estimate heavy duty coating longevity through reliability evaluation method and used combined cyclic anti-conrrosion test method composed of drying, moisturizing and salt spray as for accelerated life test to estimate longevity. Accelerated life test hours to heavy duty coating of first grade (with longevity not less than 15 years) specification may be obtained from troubleless test hours $t_n=\frac{B_p}{n^{1/\beta}}\left[\frac{1n(1-CL)}{1n(1-p)} \right]^{1/\beta}=19.671$ (yr) where shape parameter $\beta=1.1$, confidence level CL=80 %, warranty life $B_{10}=15$ yr and sampling size n=10 (2 sets). Because acceleration factor {AF} found by accelerated test is 41.7, accelerated life test hours required may be represented about 4,132 hr so that if this amount of hours is converted to number of cycles(6 hr/cycle) of complex cycle corrosion resistance test then the amount is tantamount about 690 cycles. That means if there does not occur trouble failure (with defect factor sum not more than 20) during when there is performed 690 cycles of combined cyclic anti-corrosion test to heavy duty coating specimen then it signifies that there can be warranted longevity $B_{10}$ of 15 yr under condition of confidence level CL=80 %.

• Clinical and Experimental Reproductive Medicine
• /
• v.40 no.2
• /
• pp.83-89
• /
• 2013

Objective: To investigate outcomes of stimulated IVF cycles in which GnRH antagonist was omitted on the ovulation triggering day. Methods: A total of 86 women who underwent controlled ovarian hyperstimulation with recombinant FSH and GnRH antagonist flexible multiple-dose protocols were recruited and prospectively randomized into the conventional group (group A) or cessation group (group B). The GnRH antagonist, 0.25 mg/day of cetrorelix, was started when the leading follicle reached 14 mm in diameter and was continuously administered until the hCG triggering day (group A, 43 cycles) or until the day before hCG administration (group B, 43 cycles). The maturity of oocytes, fertilization rate, embryo quality, and implantation and clinical pregnancy rates were evaluated. Results: The duration of ovarian stimulation, total dose of gonadotropins, serum estradiol levels on hCG administration day, and number of oocytes retrieved were not significantly different between the two groups. The total dose of GnRH antagonist was significantly lower in group B than group A ($2.5{\pm}0.9$ vs. $3.2{\pm}0.8$ ampoules, p<0.05). There was no premature luteinization in any of the subjects. The proportion of mature oocytes and fertilization rate were not significantly different in group B than group A (70.7% vs. 66.7%; 71.1% vs. 66.4%, respectively). There were no significant differences in the implantation or clinical pregnancy rates. Conclusion: Our prospective randomized study suggested that cessation of GnRH antagonist on the hCG administration day during a flexible multiple-dose protocol could reduce the total dose of GnRH antagonist without compromising its effects on pregnancy rates.

• Computers and Concrete
• /
• v.29 no.3
• /
• pp.187-199
• /
• 2022

The usability of waste materials as raw materials is necessary for sustainable production. This study investigates the effects of different powder materials used to replace cement (0%, 5% and 10%) and standard sand (0%, 20% and 30%) (basalt, limestone, and dolomite) on the compressive strength (f_c), flexural strength (f_r), and ultrasonic pulse velocity (UPV) of mortars exposed to freeze-thaw cycles (56, 86, 126, 186 and 226 cycles). Furthermore, the usability of artificial intelligence models is compared, and the prediction accuracy of the outputs is examined according to the inputs (powder type, replacement ratio, and the number of cycles). The results show that the variability of the outputs was significantly high under the freeze-thaw effect in mortars produced with waste powder instead of those produced with cement and with standard sand. The highest prediction accuracy for all outputs was obtained using the adaptive-network-based fuzzy inference system model. The significantly high prediction accuracy was obtained for the UPV, f_c, and f_r of mortars produced using waste powders instead of standard sand (R² of UPV, f_c and f_f is 0.931, 0.759 and 0.825 respectively), when under the freeze-thaw effect. However, for the mortars produced using waste powders instead of cement, the prediction accuracy of UPV was significantly high (R²=0.889) but the prediction accuracy of f_c and f_r was low (R²f_c=0.612 and R²f_f=0.334).

• Journal of the Earthquake Engineering Society of Korea
• /
• v.28 no.1
• /
• pp.33-39
• /
• 2024

Understanding the behavior of soil under cyclic loading conditions is essential for assessing its response to seismic events and potential liquefaction. This study investigates the effect of non-plastic fines content (FC) on excess pore pressure generation in medium-density sand-silt mixtures subjected to strain-controlled cyclic direct simple shear (CDSS) tests. The investigation is conducted by analyzing excess pore pressure (EPP) ratios and the number of cycles to liquefaction (Ncyc-liq) under varying shear strain levels and FC values. The study uses Jumunjin sand and silica silt with FC values ranging from 0% to 40% and shear strain levels of 0.1%, 0.2%, 0.5%, and 1.0%. The findings indicate that the EPP ratio increases rapidly during loading cycles, with higher shear strain levels generating more EPP and requiring fewer cycles to reach liquefaction. At 1.0% and 0.5% shear strain levels, FC has a limited effect on Ncyc-liq. However, at a lower shear strain level of 0.2%, increasing FC from 0 to 10% reduces Ncyc-liq from 42 to 27, and as FC increases further, Ncyc-liq also increases. In summary, this study provides valuable insights into the behavior of soil under cyclic loading conditions. It highlights the significance of shear strain levels and FC values in excess pore pressure generation and liquefaction susceptibility.

• Clinical and Experimental Reproductive Medicine
• /
• v.44 no.2
• /
• pp.85-89
• /
• 2017

Objective: The aim of this study was to explore the effects of the insemination method on the outcomes of elective blastocyst culture. Methods: We retrospectively analyzed the outcomes of elective blastocyst culture performed between January 2011 and December 2014. Results: There were 2,003 cycles of conventional in vitro fertilization (IVF) and 336 cycles of intracytoplasmic sperm injection (ICSI), including 25,652 and 4,164 embryos that underwent sequential blastocyst culture, respectively. No significant differences were found in the female patients' age, basal follicle-stimulating hormone level, basal luteinizing hormone level, body mass index, number of oocytes, maturity rate, fertilization rate, or good-quality embryo rate. However, the blastocyst formation rate and embryo utilization rate were significantly higher in the conventional IVF group than in the ICSI group (54.70% vs. 50.94% and 51.09% vs. 47.65%, respectively, p<0.05). The implantation/pregnancy rate (IVF, 50.93%; ICSI, 55.10%), miscarriage rate (IVF, 12.57%; ICSI, 16.29%), and live birth rate (IVF, 42.12%; ICSI, 44.08%) were similar (p>0.05). No cycles were canceled due to the formation of no usable blastocysts. Conclusion: Although the fertilization method had no effect on clinical outcomes, the blastocyst formation rate and embryo utilization rate in the ICSI group were significantly lower than those observed in the conventional IVF group. Therefore, more care should be taken when choosing to perform blastocyst culture in ICSI patients.

• The Korean Journal of Emergency Medical Services
• /
• v.28 no.2
• /
• pp.99-108
• /
• 2024

Purpose: This study aimed to compare the effectiveness of one-hand compression method (one-hand) and two-thumb compression methods (two-thumb) using a 3-year-old pediatric mannequin. Methods: Participants in the experiment were randomly assigned to 21 people with one hand and 21 people with two thumbs, who had completed a basic life support training course. The mannequin used a few junior QCPR manikis (Laerdal, Norway), based on an age of 3. The study followed the guidelines for two-rescuer pediatric CPR, performing chest compressions and ventilations in a 15:2 ratio for 5 cycles, 10 minutes. The chest compression number, depth, speed rate, and recoil rate were measured after 1, 3, and 5 cycles, respectively. Data were analyzed using SPSS 23.0. Results: Comparing the efficiency of chest compressions performed during 1, 3, and 5 cycles, the depth of chest compressions was 40.84±3.10 mm for the two thumbs and 51.48±4.79 mm for the one-hand, which was significantly different (p<.001). According to pediatric CPR guidelines, the frequency corresponding to the compression depth range of 40.00-50.00 mm was statistically higher at 57.1% (12 people) of two thumb than at 23.8% (5 people) of one hand (p<.001). Conclusion: While the current guidelines recommend one- or two-thumb encircling hand compressions for larger children, the use of one- or two-handed wrapped thumb compressions should be considered for smaller children, depending on the rescuer's judgment, when distinguishing between a child and an infant is difficult.

• Korean Journal of Materials Research
• /
• v.23 no.5
• /
• pp.266-270
• /
• 2013

The hydrogen storage properties of pure $MgH_2$ were studied and compared with those of pure Mg. At the first cycle, pure $MgH_2$ absorbed hydrogen very slowly at 573 K under 12 bar $H_2$. The activation of pure $MgH_2$ was completed after three hydriding-dehydriding cycles. At the $4^{th}$ cycle, the pure $MgH_2$ absorbed 1.55 wt% H for 5 min, 2.04 wt% H for 10 min, and 3.59 wt% H for 60 min, showing that the activated $MgH_2$ had a much higher initial hydriding rate and much larger $H_a$ (60 min), quantity of hydrogen absorbed for 60 min, than did activated pure Mg. The activated pure Mg, whose activation was completed after four hydriding-dehydriding cycles, absorbed 0.80 wt% H for 5 min, 1.25 wt% H for 10 min, and 2.34 wt% H for 60 min. The particle sizes of the $MgH_2$ were much smaller than those of the pure Mg before and after hydriding-dehydriding cycling. The pure Mg had larger hydrogen quantities absorbed at 573K under 12 bar $H_2$ for 60 min, $H_a$ (60 min), than did the pure $MgH_2$ from the number of cycles n = 1 to n = 3; however, the pure $MgH_2$ had larger $H_a$ (60 min) than did the pure Mg from n = 4 to n = 6.

• Clinical and Experimental Reproductive Medicine
• /
• v.43 no.4
• /
• pp.228-232
• /
• 2016

Objective: The aim of this study was to investigate the impact of pretreatment with transdermal estradiol ($E_2$) compared to oral contraceptive pills (OCPs) on controlled ovarian stimulation (COS) response in normal responders undergoing fresh in vitro fertilization (IVF)-embryo transfer (ET) cycles. Methods: A retrospective cohort study was performed of normal responders undergoing fresh IVF-ET cycles who received pretreatment with transdermal $E_2$ versus OCPs prior to fresh IVF-ET. The total days of ovarian stimulation, total dosage of gonadotropins, total number of oocytes, and mature oocytes retrieved were noted. Pregnancy outcomes after ET were also recorded. Results: A total of 2,092 patients met the inclusion criteria: 1,057 and 1,035 patients in the transdermal $E_2$ and OCP groups, respectively. Patients in the OCP group had a longer duration of COS ($10.7{\pm}1.63days$, p< 0.01) than the $E_2$ group ($9.92{\pm}1.94days$). Patients in the OCP group also required higher cumulative doses of gonadotropins ($2,657.3{\pm}1,187.9IU$) than those in the $E_2$ group ($2,550.1{\pm}1,270.2IU$, p= 0.002). No statistically significant differences were found in the total and mature oocytes retrieved or in the rates of biochemical pregnancy, clinical pregnancy, spontaneous miscarriage, and live birth between the groups. Conclusion: Our findings suggest that compared to OCPs, pretreatment with transdermal $E_2$ is associated with a shorter duration of ovarian stimulation and lower gonadotropin utilization, without compromising the oocyte yield or pregnancy outcomes in normal-responder patients undergoing fresh IVF.

• Journal of Embryo Transfer
• /
• v.33 no.4
• /
• pp.297-304
• /
• 2018

The purpose of the present study was to determine the elaborate characteristics of ovarian changes including follicles and corpus luteum, and hormonal patterns of gonadotropin surge mode secretions during the normal consecutive estrous cycle in three dairy cows. Non-lactating and multiparous Holstein cows (n=3) used as experimental animals. The cows were assigned to examine the relationship among ovarian changes (follicle, corpus luteum), ovarian steroids (estradiol, progesterone) and gonadotropin (LH, FSH) surge mode secretion during the successive estrous cycles by rectal palpation, ultrasonography and hormonal assay. The mean length of the estrous cycle for the three cows was $23.1{\pm}1.44days$ (${\pm}SEM$), with a range of 20-28 days. In six estrous cycles, the number of two follicular waves, three follicular waves and four follicular waves was 2, 3 and 1, respectively. The sequential ultrasonographic monitoring showed that the corpus luteum with ${\geq}10mm$ in diameter detected from Day 2 (Day 0 is ovulation) in six estrous cycles of all cows. Preovulatory increases in estradiol concentration reached $10.36{\pm}1.10pg/ml$ on the 2 days before ovulation of the last dominant follicle. All cows exhibited a preovulatory rise in estradiol concentration followed by a typical preovulatory LH and FSH surge. The mean interval from the peak of LH/FSH surge to ovulation of the last dominant follicle was $31.3{\pm}1.76h$ (${\pm}SEM$). In these results, each dairy cow showed that ovarian morphological changes and gonadotropin surge mode secretion will be regulated by various environmental factors including age, breeds, nutrition, breeding conditions, etc.

• Asian Pacific Journal of Cancer Prevention
• /
• v.13 no.3
• /
• pp.775-780
• /
• 2012

8-isoprostane (8-$isoPGF_{2{\alpha}}$) is a reliable marker and considered a gold standard for lipid peroxidation. There are very few reports of 8-isoprostane levels in cancer patients, and in patients undergoing chemotherapy. Oxidative stress is however expected and has been observed in patients with cancer. This study measured 8-isoprostane levels in urine by ELISA of 25 patients undergoing chemotherapy for advanced non-small cell lung cancer, at cycles 1, 2, and 3 of treatment. It considers the creatinine clearance of the patients, and correction of 8-isoprostane levels by creatinine clearance, and overnight urine volume methods. The average 8-isoprostane levels in urine increased more than 6 to 12 fold on chemotherapy treatment, from $532{\pm}587$ pg/mL at cycle $1,6181{\pm}4334$ at cycle 2, and $5511{\pm}2055$ at cycle 3. Similar results were obtained if 8-isoprostane levels were corrected for overnight urine volume, giving averages of $285{\pm}244{\mu}g$ at cycle $1,4122{\pm}3349$ at cycle 2, and $3266{\pm}1200$ at cycle 3. No significant difference was seen in average total overnight urine volume or number of urinations between chemotherapy cycles except for a large variation in urine volume between cycle 2 and 3. Creatinine levels were significantly different only between cycles 1 and 2 (p=0.016). In conclusion, cisplatin therapy has been shown to induce high levels of lipid peroxidation in lung cancer patients and can be assessed from the 8-isoprostane marker in overnight urine, with or without urine volume correction.