• Journal of Chest Surgery
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• 제22권2호
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• pp.246-255
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• 1989

A total and consecutive 291 patients of isolated single mitral valve replacement using the Ionescu-Shiley bovine pericardial xenograft valve operated on between October 1978 and June 1983 were retrospectively studied for the durability of the substitute valves based on the structural degeneration of primary tissue failure which had been proved on their re-replacement surgery. The mean age at the initial surgery was 32.4*12.5 years, and the operative mortality rate was 5.2 %. The early survivors of 276 patients were followed up for a total 1148.3 patient-years[mean\ulcornerD, 4.16*2.57 years]at the follow-up end of June 1988. They experienced 4 major late complications: 1.045 % thromboembolism/patient-year [pt-yr]; 0.871 % bleeding/pt-yr; 0.610% endocarditis/pt-yr; and 3.309% overall valve failure/pt-yr or 1.655% primary tissue failure/pt-yr. The actuarial survival rates were 89.4*2.2% and 87.7*2.5% at 5 and 10 years after initial surgery respectively. The probabilities of freedom from thromboembolism were 95.1*1.6% and 93.2*2.0% at 5 and 10 years after surgery. Nineteen patients underwent re-replacement of the Ionescu-Shiley valve because of primary tissue failure, and there was no operative mortality. The incidence of primary tissue failure was highest for the patients less than 15 years of age occurring in 9 out of 27 patients [33.3 %] or 8.68 %/pt-yr, while it was 4.0 % or 0.96 %/pt-yr for the rest of patients older than this age. The probabilities of freedom from primary tissue failure were 96.7*1.4 % and 84.2*3.8% at 5 and 9 years after surgery. The freedom from tissue failure increased as the age limits of cumulative younger patients were increased while it decreased as the age limits of cumulative older patients were decreased. Although it is clear that the Ionescu-Shiley valve would degenerate prematurely in young patients, the definite age limit could not be identified when the risk of early failure was significantly high.

• Advances in concrete construction
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• 제15권6호
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• pp.359-376
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• 2023

Ultra-high-performance concrete (UHPC) has become an attractive cast-in-place repairing material for existing engineering structures. The present study aims to investigate age-dependent high-early-strength UHPC (HESUHPC) material properties (i.e., compressive strength, elastic modulus, flexural strength, and tensile strength) as well as interfacial shear properties of HESUHPC-normal strength concrete (NSC) composites cured at different season temperatures (i.e., summer, autumn, and winter). The typical temperatures were kept for at least seven days in different seasons from weather forecasting to guarantee an approximately consistent curing and testing condition (i.e., temperature and relative humidity) for specimens at different ages. The HESUHPC material properties are tested through standardized testing methods, and the interfacial bond performance is tested through a bi-surface shear testing method. The test results quantify the positive development of HESUHPC material properties at the early age, and the increasing amplitude decreases from summer to winter. Three-day mechanical properties in winter (with the lowest curing temperature) still gain more than 60% of the 28-day mechanical properties, and the impact of season temperatures becomes small at the later age. The HESUHPC shrinkage mainly occurs at the early age, and the final shrinkage value is not significant. The HESUHPC-NSC interface exhibits sound shear performance, the interface in most specimens does not fail, and most interfacial shear strengths are higher than the NSC-NSC composite. The HESUHPC-NSC composites at the shear failure do not exhibit a large relative slip and present a significant brittleness at the failure. The typical failures are characterized by thin-layer NSC debonding near the interface, and NSC pure shear failure. Two load-slip development patterns, and two types of main crack location are identified for the HESUHPC-NSC composites tested in different ages and seasons. In addition, shear capacity of the HESUHPC-NSC composite develops rapidly at the early age, and the increasing amplitude decreases as the season temperature decreases. This study will promote the HESUHPC application in practical engineering as a cast-in-place repairing material subjected to different natural environments.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 B
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• pp.871-873
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• 1999

According to the reports about the failure mode analysis of modules and systems, It is said that there are many early failure of system. To remove latent defects which causes early failures like that, It is necessary that screening test is performed. ESS is often used fur screening electronic equipments, and is proposed by the most powerful tool for removing latent defects of electronic equipments. [1][2] In this report, the procedure of the environmental stress screening which uses the temperature cycling stress is proposed. It is considered about environmental conditions of distributed control system(DCS) to be tested, design specifications of the system, recommended conditions of relative IEC-STD and applied conditions of similar company. ESS test was applied at the DCS to be installed in power plant. As the results of analyzing discovered problems. It was found that almost latent defects of electronic control systems was discovered early.

• Journal of Chest Surgery
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• 제46권6호
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• pp.426-432
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• 2013

Background: Heart transplantation has become a widely accepted surgical option for end-stage heart failure in Korea since its first success in 1992. We reviewed early postoperative complications and mortality in 239 patients who underwent heart transplantation using bicaval technique in Asan Medical Center. Methods: Between January 1999 and December 2011, a total of 247 patients aged over 17 received heart transplantation using bicaval technique in Asan Medical Center. After excluding four patients with concomitant kidney transplantation and four with heart-lung transplantation, 239 patients were enrolled in this study. We evaluated their early postoperative complications and mortality. Postoperative complications included primary graft failure, cerebrovascular accident, mediastinal bleeding, renal failure, low cardiac output syndrome requiring intra-aortic balloon pump or extracorporeal membrane oxygenation insertion, pericardial effusion, and inguinal lymphocele. Follow-up was 100% complete with a mean follow-up duration of $58.4{\pm}43.6$ months. Results: Early death occurred in three patients (1.3%). The most common complications were pericardial effusion (61.5%) followed by arrhythmia (41.8%) and mediastinal bleeding (8.4%). Among the patients complicated with pericardial effusion, only 13 (5.4%) required window operation. The incidence of other significant complications was less than 5%: stroke (1.3%), low cardiac output syndrome (2.5%), renal failure requiring renal replacement (3.8%), sternal wound infection (2.0%), and inguinal lymphocele (4.6%). Most of complications did not result in the extended length of hospital stay except mediastinal bleeding (p=0.034). Conclusion: Heart transplantation is a widely accepted option of surgical treatment for end-stage heart failure with good early outcomes and relatively low catastrophic complications.

• Journal of Chest Surgery
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• 제27권9호
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• pp.764-769
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• 1994

From november, 1985 to May, 1993, 222 arteriovenous fistulae were made in 201 patients with chronic renal failure. Among them, a total of 183 arteriovenous fistulae in 173 patients were reviewed to evaluate the factors influencing patency rate of the vascular access. The results were revealed as follows: There were 102 men and 71 women,aged 10 to 76 years [mean = 45.7 years]. Sixteen patients of them had previous shunts. The procedures included establishment of 214 radiocephalic or brachioocephalic fistulae, 203 side to end, 9 side to side, 2 end to end, 2 autologous saphenous vein grafts, 6 Gore-Tex grafts. There were 28 early shunt failures[12%] due to use of 23 inadequate veins and 5 thrombosis.There were 32 late complications[14%]; 19 thrombosis, 4 aneurysm, 4 venous hypertension, 3 steal syndrome, 2 infections. There were 32 diabetic patients [17 %]. No significant differences in graft patency were noted between diabetic and nondiabetic individuals. There were no significant difference in graft patency between male and female. Overall shunt patency in 183 cases with chronic renal failure was 96% at I month, 95% at 3 months, 93% at I year, 91% at 2 years, 84% at 3 years, 56% at 5years.This Study showed that early postoperative thrombosis and diabetic vasculopathy were most causes of the vascular access failure and suggested that prevention of thrombi and well control of diabetes mellitus were most important to enhance patency rates of the vascular access.

• Clinical and Experimental Pediatrics
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• 제54권7호
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• pp.277-281
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• 2011

Failure to thrive (FTT) is a term generally used to describe an infant or child whose current weight or rate of weight gains is significantly below that expected of similar children of the same age, sex and ethnicity. It usually describes infants in whom linear growth and head circumference are either not affected, or are affected to a lesser degree than weight. FTT is a common problem, usually recognized within the first 1-2 years of life, but may present at any time in childhood. Most cases of failure to thrive involve inadequate caloric intake caused by behavioral or psychosocial issues. The most important part of the outpatient evaluation is obtaining an accurate account of a child's eating habits and caloric intake. Routine laboratory testing rarely identifies a cause and is not generally recommended. FTT, its evaluation, and its therapeutic interventions are best approached by a multi-disciplinary team includes a nutritionist, a physical therapist, a psychologist and a gastroenterologist. Long term sequelae involving all areas of growth, behavior and development may be seen in children suffering from FTT. Early detection and early intervention by a multidisciplinary team will minimize its long term disadvantage. Appropriate nutritional counseling and anticipatory guidance at each well child visit may help prevent some cause of FTT.

• 대한임상독성학회지
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• 제2권1호
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• pp.45-48
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• 2004

Paraquat, a widely used herbicide, is extremely toxic, causing multiple organ failure in human. Many treatment modality has been used, but now paraquat is very fatal drug. Elimination rate of plasma paraquat seems to be a factor for the survival rate. So early diagnosis and early treatment are very important. Plasma paraquat concentration could be measured by radioimmunoassay. But it is impossible that the test was done at Emergency room and the result was checked immediately. There was relation between plasma paraquat concentrations and urine paraquat concentration. Because of its simplicity and low cost, urine paraquat concentration test is complementary to the plasma concentration measurement. If the patient has psychotic problem or unconscious mental state, and is observed unexplained dyspnea and oral ulcer, urine paraquat test is very important to rule out acute paraquat intoxication. We experienced a patient who was presented as unexplained acute renal failure initially and was diagnosed as paraquat intoxication later.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제45권3호
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• pp.135-140
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• 2019

Objectives: This study sought to investigate the association between the systemic intake of proton pump inhibitors (PPI) and the early failure of dental implants. Materials and Methods: A retrospective cohort study involving 1,918 dental implants in 592 patients (69 implants in 24 PPI users and 1,849 implants in 568 nonusers, respectively) was conducted. The effect of PPI intake on the osseointegration of dental implants was evaluated using patientand implant-level models. Results: Among 24 PPI users, two patients experienced implant failure, one of whom had three and the other of whom had one failed implant, respectively. Thus, the rate of failure for this population was 8.3%. Separately, 11 nonusers each experienced one implant failure, and the failure rate for these patients was 1.9%. Fisher's exact test revealed statistically significant differences between PPI users and nonusers at the implant level (P=0.002) but failed to show any significance at the patient level (P=0.094). The odds of implant failure were 4.60 times greater among PPI users versus nonusers. Dental implants that were placed in patients using PPIs were found to be 4.30 times more likely to fail prior to loading. Conclusion: The findings of this study suggest that PPI intake may be associated with an increased risk of early dental implant failure.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2009년도 춘계학술대회 논문집
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• pp.162-168
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• 2009

FMEA(Failure Mode and Effect Analysis) is a failure analysis method for the system to identify the potential failure modes, and their effects and causes to reduce or mitigate the critical effects of the system. FMEA for railway was introduced with reliability of railway system, and this was used for identifying and analysing the possible hazards qualitatively to meet the requirements in early stage of business. In general, the overall failure data of system could be managed from design stage by FMEA, and also the countermeasures to prevent many predicted failures could be established by identification of failure modes and assement of failure effects by FMEA. Using these advantages of FMEA, the effectiveness of reliability improvement could be expected if FMEA is applied continuously in operation stage. It is essential that railway vehicles are maintained with high level of safety and reliability not to happen any failures in operation. This paper is proposed the proper FMEA for maintenance of railway vehicles compared with existing FMEA.

• 한국가스학회지
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• 제9권3호
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• pp.38-43
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• 2005

화학공장들을 비롯한 수많은 가스 이용 시설들에서는 방대한 양의 운전 변수들을 감시하면서 운전 상태 및 부하에 따라 설비를 제어하고 있다. 이러한 공정에서 운전자가 인식할 수 있는 공정의 이상(fault)은 물리적인 고장(physical failure)이나 외부 교란, 운전자의 오류(human error) 등과 같은 원인으로 인하여 공정의 운전 조건이 정해진 상태를 벗어난 비정상(abnormal) 상태가 지속적으로 누적되면서 발생한다 이러한 공정의 이상이 발생하기 전부터 비정상 상태가 지속됐다는 것에 기초하여, 운전 변수들을 실시간으로 감시하여 공정 상태의 판단을 도와주고, 공정의 이상이 발생하기 전에 조기 경보를 해주는 조기 경보 시스템에 대해 연구하였다.