• Food Science and Biotechnology
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• 제17권6호
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• pp.1131-1138
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• 2008

Diabetic complications are a leading cause of blindness, renal failure, and nerve damage. Additionally, diabetes-accelerated atherosclerosis leads to increased risk of myocardial infarction, stroke, and limb amputation. At the present time, 4 main molecular mechanisms have been implicated in hyperglyceamia-mediated vascular damage. In particular, advanced glycation endproducts (AGE), which are formed by complex, heterogeneous, sugar-derived protein modifications, have been implicated as a major pathogenic process for diabetic complications. Recently, AGE inhibitors such as aminoguanidin, ALT-946, and pyridoxamine have been reported. Such an integrating paradigm provides a new conceptual framework for future research on diabetes complications and on discovering drugs to prevent the progression of AGE-induced maladies.

• 한국추진공학회지
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• 제18권3호
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• pp.17-25
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• 2014

본 논문은 장약포의 저장기간에 따른 파단하중 저하에 관하여 감마과정 모델을 이용하여 저장수명을 예측하는 방법에 대한 연구결과이다. 추진제의 자연분해로 발생하는 질소화합물과 장약포의 화학반응은 파단하중을 저하시킨다. 장약포의 가속수명시험 결과에 감마과정 모델을 적용하여 시간의 경과에 따른 상태와 수명을 확률분포로 표현하였다. 저장수명은 중위수로 표현하고 품질보증을 위한 정책결정기준으로 $B_1$ 또는 $B_5$ 수명을 활용하는 것이 적절하다.

• Genomics & Informatics
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• 제21권3호
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• pp.28.1-28.13
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• 2023

Mild cognitive impairment (MCI) is a clinical syndrome characterized by the onset and evolution of cognitive impairments, often considered a transitional stage to Alzheimer's disease (AD). The genetic traits of MCI patients who experience a rapid progression to AD can enhance early diagnosis capabilities and facilitate drug discovery for AD. While a genome-wide association study (GWAS) is a standard tool for identifying single nucleotide polymorphisms (SNPs) related to a disease, it fails to detect SNPs with small effect sizes due to stringent control for multiple testing. Additionally, the method does not consider the group structures of SNPs, such as genes or linkage disequilibrium blocks, which can provide valuable insights into the genetic architecture. To address the limitations, we propose a Bayesian bi-level variable selection method that detects SNPs associated with time of conversion from MCI to AD. Our approach integrates group inclusion indicators into an accelerated failure time model to identify important SNP groups. Additionally, we employ data augmentation techniques to impute censored time values using a predictive posterior. We adapt Dirichlet-Laplace shrinkage priors to incorporate the group structure for SNP-level variable selection. In the simulation study, our method outperformed other competing methods regarding variable selection. The analysis of Alzheimer's Disease Neuroimaging Initiative (ADNI) data revealed several genes directly or indirectly related to AD, whereas a classical GWAS did not identify any significant SNPs.

• Journal of Chest Surgery
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• 제21권4호
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• pp.619-629
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• 1988

The increasing number of replacement of the substitute cardiac valves were seen in these 2 years. Out of a total 1,408 patients with cardiac valve replacement, 54 required replacement of the substitute valves. Fifty-nine substitute valves replaced were 43 in mitral, 14 in aortic and 2 in tricuspid positions; and they were 36 Ionescu-Shiley, 15 Hancock and 3 Angell-Shiley bioprosthetic valves and 3 St. Jude Medical and 2 Bjork-Shiley prosthetic valves. Primary tissue failure was the most frequent reason of replacement[38 patients] followed by paravalvular leak[9 patients], prosthetic valve endocarditis[6 patients] and valve thrombosis[1 patient] in order. The most pronounced pathology of the failed xenograft valves seen in the primary tissue failure group was calcification and fixation of the cusps with or without tear and defect of the cuspal tissue. The operative mortality rate was 7.4%. Fifty early survivors were followed up for a total of 82.6 patient-years and there was no late death. Actuarial survival rate was 92.3*3.8% at 6 years after surgery. Although the definite tendency toward early and accelerated degeneration of the xenograft valves has been seen in patients younger than 20 to 25 years of age, no strict age limit from where the tissue failure slows down could be determined. The requirement of the ideal substitute valves would be the durability of the recently developed mechanical prostheses armed with the low thrombogenicity of the bioprostheses. At the present time, the need of compromise in selection between less thrombogenic bioprosthetic and more durable mechanical valves should be stressed. The difficulty in choice is yet important in patients of middle age and children where the use of homograft valves may be one of the solution despite of certain limitations from sociomedical reasons.

• 한국사회복지학
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• 제37권
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• pp.1-31
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• 1999

실직자의 재취업 실태 및 실업기간에 관한 실증연구는 지난 수 십년간 실업(고용)보험의 연구에 있어 중요한 부분을 차지하여 왔지만, 우리나라에서는 이러한 주제에 관한 체계적 실증 연구가 매우 부족한 실정이다. 본 연구는 1996년 7월부터 1997턴 12월까지 18개월간 총 60,141명의 실업급여 수급권자 중 1997년 6월까지의 실업급여 수급권자 40,175명을 대상으로 생존분석의 Life table 분석과 Accelerated Failure Time 모델분석을 실시하여, 실직자 및 실업급여 관련 변수들이 실업탈피 기대기간(expected unemployment period)에 미치는 영향력을 측정 분석하였다. 생존분석결과 최장 실직기간까지 실업상태로 남아있는 수급권자들의 비율(누적생존율)이 64.83%나 되었다. Accelerated Failure Time 모델 중 Log-Normal Model에 의한 분석결과 교육수준과 상시근로자수를 제외한 대부분의 독립변수들이 재취업까지의 기대기간에 통계적으로 유의미한 영향력을 미치는 것으로 나타났다. 이러한 실종분석 결과를 바탕으로 고학력, 고임금을 받던 화이트칼라 노동자들에 대한 적극적 노동시장정책의 필요성과 지역 및 업종의 재취업여건 차이를 감안한 실업대책의 필요성을 제언하였으며, 실업급여의 제도적 변수가 나타내는 순수한 효과를 파악하기 위한 다각적인 후속연구의 필요성을 제기하였다.

• 한국안전학회지
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• 제15권1호
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• pp.28-35
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• 2000

As huge energy transfer systems like a nuclear power plant, steam power plant and petrochemical plant are operated for a long time, mechanical properties are changed by degradation. The life time of the systems can be affected by the mechanical properties. So determination of the integrity of the metallic structure is required either to en4sure that failure will not occur during the service life of the components or to evaluate the lifetime extension of the structure. An automated ball indentation(ABI) method was developed as a non-destructive technique for evaluating the integrity of such metallic components. In this paper, we would like to present the aging evaluation technique by the ABI method. The five classes of the thermally aged CF8M specimens were prepared using an artificially accelerated aging method. After holding 100, 300, 900, 1800 and 3600 hours at 43$0^{\circ}C$, the specimens were cooled down using water to room temperature respectively. The tensile test, hardness test, charpy impact test, ABI test were performed. The results of the fracture test were compared with those of ABI test and the new evaluation technique of the integrity of metallic structures was developed.

• 한국결정성장학회지
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• 제19권2호
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• pp.102-105
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• 2009

$BaTiO_3$ 입자 크기가 MLCCs의 절연 특성 및 MLCCs 특성 열화에 미치는 영향을 알아보기 위해 서로 다른 입자를 사용하여 제작한 MLCCs의 가속열화시험을 $150^{\circ}C$, 75 V조건에서 실시하였다. 실험에 사용된 MLCCs는 각각 $0.525{\mu}m$, $0.555{\mu}m$, $0.580{\mu}m$의 입자 크기를 가지는 $BaTiO_3$와 Ni계 전극을 사용하여 상용화된 공정을 통해 제조되었다. 제조된 MLCCs에 대해 정상 유무 확인을 위해 X5R조건 하에서 TCC(Temperature Coefficient of Capacitance) 측정을 통해 유전 변화율에 대해 알아보았다. 세 가지 입자 크기에 따른 절연저항의 거동을 알아보기 위해 BDV(Breakdown Voltage)를 실시하였고, 가속열화시험 후 입자의 크기에 따른 MLCCs 열화의 정도와 원인을 알아보기 위해 XPS(If-ray photoelectron spectroscopy)를 통해 고장분석을 하였다. $BaTiO_3$의 입자 크기가 작을수록 절연파괴저항 및 절연저항 열화에 우수한 특성을 나타내었고, XPS 분석 결과 확인된 NiO peak과 $BaTiO_3$ peak 감소를 통해 MLCCs 열화원인이 유전체의 산소 환원과 환원된 산소와 전극간 반응임을 알 수 있었다.

• Corrosion Science and Technology
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• 제14권1호
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• pp.1-11
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• 2015

Local wall thinning and integrity degradation caused by several mechanisms, such as flow accelerated corrosion (FAC), cavitation, flashing and/or liquid drop impingements, are a main concern in carbon steel piping systems of nuclear power plant in terms of safety and operability. Thinned pipe management program (TPMP) had been developed and optimized to reduce the possibility of unplanned shutdown and/or power reduction due to pipe failure caused by wall thinning in the secondary side piping system. This program also consists of several technical elements such as prediction of wear rate for each component, prioritization of components for inspection, thickness measurement, calculation of actual wear and wear rate for each component. Decision making is associated with replacement or continuous service for thinned pipe components. Establishment of long-term strategy based on diagnosis of plant condition regarding overall wall thinning is also essential part of the program. Prediction models of wall thinning caused by FAC had been established for 24 operating nuclear plants. Long term strategies to manage the thinned pipe component were prepared and applied to each unit, which was reflecting plant specific design, operation, and inspection history, so that the structural integrity of piping system can be maintained. An alternative integrity assessment criterion and a computer program for thinned piping items were developed for the first time in the world, which was directly applicable to the secondary piping system of nuclear power plant. The thinned pipe management program is applied to all domestic nuclear power plants as a standard procedure form so that it contributes to preventing an accident caused by FAC.

• 한국지반환경공학회 논문집
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• 제11권10호
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• pp.15-24
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• 2010

지중전력선은 연성관을 다발로 지하에 매설함으로 관의 하단부 다짐효율이 낮아 파손 등과 같은 구조적 문제점에 항상 노출되어 있고 이러한 문제점을 해결하기 위해서 다양한 방법들이 강구되어 왔으며 그중 하나가 유동성이 뛰어난 저강도 콘크리트의 개발이다. 그러나 지중전력선 뒤채움재는 이러한 구조적 안정성 뿐만 아니라 전력선에서 발생하는 열을 효율적으로 외부로 배출시키는 우수한 열적 특성도 동시에 요구된다. 따라서 본 연구에서는 급결성 유동성 뒤채움재의 물리, 역학적 조건에 따른 열 저항특성을 파악하고자 한다. 국내 토질조건을 고려하여 풍화토, 자갈, 점토를 혼합한 혼합토 총 17종류의 다양한 토양에 대해서 고화재를 적용하여 물리, 역학적 특성(함수비, 단위 중량, 간극비, 양생 시간)에 따른 열저항 특성을 파악하고, 현장의 적용성을 확인하고자 실증실험을 수행하였다. 연구결과, 실제 지반조건과 유사한 17종 혼합토에 대해서 수축팽창, 양생조건을 고려한 실내실험과 현장토에 대해서 실험을 수행한 결과, 다양한 현장조건에 대해서 $85^{\circ}C\;cm/W$ 이하 열 저항성 값으로 우수한 열특성을 나타냈다.

• Journal of Chest Surgery
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• 제16권2호
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• pp.139-146
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• 1983

Between 1974 and 1982, 31 patients from 7 to 15 years of age have undergone valve replacement for their acuqired cardiac valvular diseases at Seoul National University Hospital. Furteen patients (45.2%) had a definite history of rheumatic fever and only 4 patients (12.9%) had atrial fibrillation on their preoperative electrocardiograms. Characteristically, the valvular lesions were ones of insufficiency with or without associated stenosis in all patients except only one whose mitral valve was tightly stenotic. Thrity-seven valves were replaced in 31 patietns including a case of successful replacement of his failed xenogragt mitral valve : 4 mechanical valves were used in 3 patients and 33 xenograft valves were used in the remaining 28 patients. The size of the valves were not the major problem at the time of opertion because most of the patients had a dilated heart from disease. There were 3 diaths within 30 days of surgery (9.7% operative mortality rate) and 3 late deaths (9.7% late mortality rate) with an overall mortality rate of 19.4%. Twenty-eight early survivors were followed up for a total of 488 patient-months. Thromboembolic complications occurred in 5 patients with 2 deaths: cmbolic rate of 17.9% or the actuarial embolic incidence of 12.29%/patients-year. four xenograft tissue valves in 4 patients had failed during the period from 19 to 41 months of surgery with an overall valve failure rate of xenograft of 14.3% or the actuarial incidence of 9.84% failure/patient-year. One of these 4 patients had required replacement of his failed mitral xenograft valve which had severe calcification and tissue disruption with primary tissue failure rate of 3.6% or the actuarial incidence of 3.13% failure/patient-year. The actuarial survial including the operative morality was 50.0% at 5 years of surgery. /the actuarial incidence free from thromboembolism in bioprosthetic group was 85.4% at 42 months, while it was 33.4% in mechanicial group at 60 months after operation. The actuarial incidence free from overall valve failur of 100.0% until 18 months after surgery was followed by a rapid decrease during the next 2-year period, and it was only 17.8% at the follow-up end of 42 months after surgery. It was suggested that the major advantage of low thrombogenecity with xenograft valve should be balanced against the high incidence of accelerated valve failure when it is used in children whose age is younger than 15 years old. The possible role of recurrent rheumatic attacks to the early failure of xenograft tissue valve was also discussed.