• 대한생식의학회:학술대회논문집
• /
• 대한불임학회 2003년도 제44차 춘계학술대회
• /
• pp.39-46
• /
• 2003

• 대한생식의학회:학술대회논문집
• /
• 대한불임학회 2003년도 제44차 춘계학술대회
• /
• pp.47-53
• /
• 2003

• 한국발생생물학회지:발생과생식
• /
• 제4권1호
• /
• pp.61-66
• /
• 2000

본 연구에서는 조기 난소 부전증 환자를 대상으로 난포 자극 호르몬 수용체 유전자의 돌연변이와 발현 양상을 분석하였다. 돌연변이 분석을 위해 환자의 말초혈액에서 genomic DNA를 분리하고 nucleotide 566을 포함하고 있는 exon 7에 특이적인 primer쌍을 이용하여 중합효소 연쇄 반응을 시행하였다. 전기 영동으로 반응산물을 확인한 다음, 돌연변이 여부를 조사하기 위하여 제한효소 절단분석 (Restriction Fragment Length Polymorphism, RFLP)을 시행한 결과, 대조군과 조기 난소 부전증 환자군 모두에서 돌연변이를 관찰할 수 없었다. 난포 자극 호르몬 수용체의 발현양상을 확인하기 위해 시험관아기 시술과정 중 난자 채취과정에서 얻어진 황체화 과립세포에서 total RNA를 추출하여 역전사 중합효소 연쇄 반응을 시행하였다. 반응 산물을 전기 영동하여 발현양상을 비교해 본 결과, 대조군에 비해 조기 난소 부전증 환자군에서 난포 자극 호르몬 수용체 유전자의 발현이 다소 낮은 것으로 확인되었다. 이상의 결과로 보아 조기 난소 부전증 환자에서 난포 자극 호르몬 수용체 유전자의 돌연변이는 발견할 수 없었으며 난포 자극 호르몬 수용체 유전자의 발현이 대조군에 비해 낮아 과배란 유도시에 생식소 자극 호르몬에 대해 저적응증을 보이며 난포형성과정에도 장애를 받는 것으로 사료된다.

• Tribology and Lubricants
• /
• 제31권6호
• /
• pp.281-286
• /
• 2015

Automotive transmission systems are assembled with a large number of gears and shafts, and rolling bearings are used to ensure their smooth operation. Gear oil in the gear box contains solid particles such as wear debris from contacting gears and metallic chips. This particle-enriched lubricating oil can cause premature failure of the rolling bearings. Research aimed at improving the service life of these rolling bearings has been confined mainly to design and lubrication of the inner/outer rings and the rolling elements. In this paper, we redesigned the shape of the cage pocket of a deep groove ball bearing to reduce the premature failure due to particle contamination. Test bearings are assembled with this new cage design containing a hole punched in the cage pocket. Endurance tests are carried out using the contaminated lubricating oil with miracle grid as hard particle. The duration and damaged bearing component shapes are compared for two different cages. The B₁₀ life of bearing with new cage is increased by about 66% compared to the conventional cage. This is because the hard particles can be easily discharged through the pocket hole without staying for a long time in the lubrication regions. This greatly decreases abrasive wear and dents on the highly stressed ball bearing surfaces. Therefore, the cage design of this study, containing a pocket hole, can significantly delay the premature failure of rolling bearings and improve the endurance life.

• 한국콘크리트학회:학술대회논문집
• /
• 한국콘크리트학회 2003년도 봄 학술발표회 논문집
• /
• pp.531-536
• /
• 2003

It is generally known that RC flexural members strengthened by GFRP(Glass Fiber Reinforced Polymers) tend to be failed by premature bond failure near the flexural-shear cracks happened at the mid-span of beams. It is therefore strongly recommended that premature bond failure must be avoided to insure the intended strengthening effects sufficiently. The various methodologies such as increasing bonded length of GFRP and bonding details including U-shape wrappings and epoxy shear-keys are examined in this study. The bonded length of GFRP are calculated based on the assumed bond strengths of epoxy saturating resin. Total six half scale RC beam specimens were constructed and tested to investigate the effectiveness of each methodologies to prevent the bond failure of GFRP. Test results of each specimens are discussed in this paper.

• 한국복합재료학회:학술대회논문집
• /
• 한국복합재료학회 2005년도 추계학술발표대회 논문집
• /
• pp.61-65
• /
• 2005

Existing test methods for thick-section specimens ( 4mm) have not provided precise compressive properties to date for the analysis and design of thick structure. A survey of the failure behaviour of such thick specimens revealed that the failure initiated at the top corner of the specimen and propagated down and across the width of the specimen as premature failure, not typically reported for thin compression specimens. In the current study, the premature failure was successfully avoided during compressive testing and the failure mode was quite similar regardless of increasing specimen thickness and specimen volume. Failure mode was similar regardless of increasing specimen thickness and specimen volume, i.e. brooming failure mode combined with longitudinal splitting, interlaminar cracking, fibre breakage and kinkband formation (fibre microbuckling). Nevertheless, average failure strengths of the specimens decreased with increasing specimen thicnkiness from 2mm to 8mm with the T800/924C system (36% strength reduction) and specimen volumes from scaling factor I to scaling factor 4 with the IM7/8552 system (46% strength reduction). It was revealed from the literature$^{11}$ that the thickness effect and scaling effect arc caused by manufacturing defects such as void content and fibre waviness.

• Structural Engineering and Mechanics
• /
• 제86권6호
• /
• pp.779-791
• /
• 2023

Long-termly used in water supply, an underground concrete pipe is easily subjected to the coupled action of pressure loading and flowing water, which can cause the chemo-mechanical damage of the pipe, resulting in its premature failure and lifetime reduction. Based on the leaching characteristics and damage mechanism of concrete pipe, this paper proposes a coupled chemo-mechanical damage and failure model of underground concrete pipe for water supply, including a calcium leaching model, mechanical damage equation and a failure criterion. By using the model, a numerical simulation is performed to analyze the failure process of underground concrete pipe, such as the time-varying calcium concentration in concrete, the thickness variation of pipe wall, the evolution of chemo-mechanical damage, the distribution of concrete stress on the pipe and the lifetime of the pipe. Results show that, the failure of the pipe is a coupled chemo-mechanical damage process companied with calcium leaching. During its damage and failure, the concentrations of calcium phase in concrete decrease obviously with the time, and it can cause an increase in the chemo-mechanical damage of the pipe, while the leaching and abrasion induced by flowing water can lead to the boundary movement and wall thickness reduction of the pipe, and it results in the stress redistribution on the pipe section, a premature failure and lifetime reduction of the pipe.

• Clinical and Experimental Reproductive Medicine
• /
• 제41권3호
• /
• pp.120-124
• /
• 2014

Objective: The aim of the present study was to examine whether interactions between polymorphisms in the thyroglobulin and ADAM metallopeptidase with thrombospondin type 1 motif, 16 (ADAMTS16) genes are associated with the development of premature ovarian failure (POF). Methods: A total of 75 patients with POF and 196 controls were involved in this study. We used a GoldenGate assay to genotype single nucleotide polymorphisms (SNPs). Logistic regression analysis was performed to identify POF-associated polymorphisms and synergistic interactions between polymorphisms in the thyroglobulin and ADAMTS16 genes. Results: Single gene analyses using logistic regression analysis showed no significant association between polymorphisms in the two genes and POF. In the results from interaction analyses, we found seven synergistic interactions between the polymorphisms in thyroglobulin and ADAMTS16, although there was no combination showing p-values lower than the significant threshold using the Bonferroni correction. When the AG genotype was present at the rs853326 missense SNP, the A and G alleles at the tagging SNPs rs16875268 and rs13168665 showed significant interactions (odds ratios=5.318 and 16.2 respectively; 95% confidence intervals, 1.64-17.28 and 2.08-126.4; p=0.0054 and 0.0079). Conclusion: Synergistic interactions between polymorphisms in the thyroglobulin and ADAMTS16 genes were associated with an increased risk of POF development in Korean women.

• Clinical and Experimental Pediatrics
• /
• 제61권10호
• /
• pp.315-321
• /
• 2018

Purpose: To investigate the effectiveness of transient intubation for surfactant administration and extubated to nasal continuous positive pressure (INSURE) for treatment of respiratory distress syndrome (RDS) and to identify the factors associated with INSURE failure in extremely premature infants. Methods: Eighty-four infants with gestational age less than 28 weeks treated with surfactant administration for RDS for 8 years were included. Perinatal and neonatal characteristics were retrospectively reviewed, and major pulmonary outcomes such as duration of mechanical ventilation (MV) and bronchopulmonary dysplasia (BPD) plus death at 36-week postmenstrual age (PMA) were compared between INSURE (n=48) and prolonged MV groups (n=36). The factors associated with INSURE failure were determined. Results: Duration of MV and the occurrence of BPD at 36-week PMA were significantly lower in INSURE group than in prolonged MV group (P<0.05), but BPD plus death at 36-week PMA was not significantly different between the 2 groups. In a multivariate analysis, a reduced duration of MV was only significantly associated with INSURE (P=0.001). During the study period, duration of MV significantly decreased over time with an increasing rate of INSURE application (P<0.05), and BPD plus death at 36-week PMA also tended to decrease over time. A low arterial-alveolar oxygen tension ratio (a/APO2 ratio) was a significant predictor for INSURE failure (P=0.001). Conclusion: INSURE was the noninvasive ventilation strategy in the treatment of RDS to reduce MV duration in extremely premature infants with gestational age less than 28 weeks.

• 한국유전체학회:학술대회논문집
• /
• 한국유전체학회 2006년도 The 15th Korean Genome Organization Conference KOGO 2006 Annual Meeting
• /
• pp.48-48
• /
• 2006