• The Journal of Advanced Prosthodontics
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• 제12권3호
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• pp.140-149
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• 2020

PURPOSE. This study evaluated the color stabilities of two computer-aided design and computer-aided manufacturing (CAD/CAM) blocks and a nanofill composite resin and the microtensile bond strength (µTBS) between the materials. MATERIALS AND METHODS. Twelve specimens of 4 mm height were prepared for both Lava Ultimate (L) and Vita Enamic (E) CAD/CAM blocks. Half of the specimens were thermocycled (10,000 cycle, 5° to 55℃) for each material. Both thermocycled and non-thermocycled specimens were surface treated with one of the three different methods (Er,Cr:YSGG laser, bur, or control). For each surface treatment group, one of the thermocycled and one of non-thermocycled specimens were restored using silane (Ceramic Primer II), universal adhesive (Single Bond Universal), and nanofill composite resin of 4-mm height (Filtek Ultimate). The other specimens were restored with the same procedure without using silane. For each group, 1 × 1 × 8 mm bar specimens were prepared using a microcutting device. Bar specimens were thermocycled (10,000 cycle, 5° to 55℃) and microtensile tests were performed. Staining of the materials in coffee solution was also compared using a spectrophotometer. Data were analyzed using one-way ANOVA, t-test and post-hoc Scheffe tests. RESULTS. µTBS were found similar between the thermocycled and non-thermocycled groups (P>.05). The highest µTBS (20.818 MPa) was found in the non-thermocycled, bur-ground, silane-applied E group. Silane increased µTBS at some E groups (P<.05). Composite resin specimens showed more staining than CAD/CAM blocks (P<.05). CONCLUSION. CAD/CAM blocks can be repaired with composite resins after proper surface treatments. Using silane is recommended in repair process. Color differences may be shown between CAD/CAM blocks and the nanofill composite after a certain time period.

• 한국건설관리학회논문집
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• 제19권5호
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• pp.3-9
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• 2018

기술제안입찰의 주 평가요소 중 하나인 생애주기비용의 적정성은 평가의 전문성을 요하지만 평가에 필요한 시간이 절대적으로 부족하여 경험많은 평가자라 할지라도 단순한 수치 비교에 의한 상대평가에 그치는 경향이 많았다. 이에 본 연구에서는 기술제안입찰로 낙찰자를 선정한 실 사례와 기술제안서를 비교하고 110건의 기술제안입찰 제안서를 비교하여 생애주기비용 중 가장 변동 폭이 큰 유지관리 및 에너지 비용의 불확실성을 분석하였다. 또한 절감된 공사비 대비 유지관리 및 에너지 비용의 절감수준을 정규화하기 위하여 VE지수를 제시하였다. 프로젝트별로 상이한 수선 및 교체 주기, 수선과 교체의 중복, 비수선 항목, 그리고 기타 에너지비 등의 중복 적용이 VE지수의 불확실성을 가장 확대시키는 요인으로 분석되었으며, 이러한 요인의 중복을 제거한 유지관리 및 에너지 비용 산출법을 표본 기술제안 사업 35건에 적용하여 평균 1.38, 표준편차는 1.19를 가지는 VE지수 모집단을 도출하였다. 기술제안 입찰의 평가자는 다수의 제안안 중 가장 합리적으로 산출된 VE지수를 추정하기 위해, 특정 VE지수를 본 연구가 제안하는 모집단 분포에 비교하여 그 확률을 계산하는 결정론적 해석 방법 또는 불확실성을 고려한 확률론적 해석 방법을 사용할 수 있다.

• Journal of Advanced Marine Engineering and Technology
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• 제31권1호
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• pp.84-94
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• 2007

As a reactor coolant pump(RCP) is operated in the nuclear power system for a long time. so its surface is continuously contaminated by radioactive scales. In order to perform regular or emergency repair about RCP internals a special decontamination process should be used to reduce the radiation from the RCP surface by means of chemical cleaning. In this study, applicable possibility in chemical decontamination for RCP was investigated on the various materials. The STS 304 showed the best electrochemical properties for corrosion resistance than other materials. However, the pitting corrosion was slightly generated in both STS 415 and STS 431 with the increasing numbers of cycle and intergranular corrosion were sporadically observed. The size of their pitting corrosion and intergranular corrosion were also increased with increasing cycle numbers.

• KIEAE Journal
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• 제3권3호
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• pp.67-74
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• 2003

The repair and maintenance planning is the principal transaction to prevent from the degradation of apartment buildings to prolong their lives. Various building components as part of living area should be maintained properly and timely before critical defects are realized, then the building life might be extended until the limit of its usability. In other words, various building components such as utilities, finishes and structural members are needed to be repaired and replaced in different time interval after completion. To do this systematically, a maintenance management system for Long-Range Planning (LRP) needs developing. The LRP should be figured out based on the forecast of repairing and replacing cycle of building components according to work trades. And the precise forecast of repairing and replacing time of the components helps to enhance the usability of the developed system. The purpose of this paper is to suggest a system with which apartment building managers carry out the tasks of periodical check, diagnosis and replacement of building components based on the maintenance calendar. By using the system, they can easily forecast repairing and replacing time of the components with the consideration of life cycle of building materials and build the LRP.

• 한국군사과학기술학회지
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• 제2권2호
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• pp.166-172
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• 1999

Weapon system is defined as a combination of primary system and logistics support system which are evaluated by capability and operational availability respectively. Weapon system developer thought that primary system was weapon system and also only primary system was important. Recent comparison of total life cycle cost showed that logistics support system was proved to be more important than primary system. However, until now no systematic approach to logistics support system development have applied in the area of developing support system and much money was exhausted by wrong logistics support system. We need to construct a universal metric for effectiveness of logistics support system and to cut out whatever activities or support elements which do not contribute to the metrics. This study describes a new approach under the name function approach to logistics support system development and also classifies five factors of failure frequency, stock out of frequency, administrative delay time, active repair time and logistic delay time that have influence on operational availability of logistics support system.

• Biomolecules & Therapeutics
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• 제20권1호
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• pp.81-88
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• 2012

Histone deacetylases (HDACs) are enzymes involved in the remodelling of chromatin, and have a key role in the epigenetic regulation of gene expression. Histone deacetylase (HDAC) inhibitors are emerging as an exciting new class of potential anti-cancer agents. In recent years, a number of structurally diverse HDAC inhibitors have been identifi ed and these HDAC inhibitors induce growth arrest, differentiation and/or apoptosis of cancer cells in vitro and in vivo. However, the underlying molecular mechanisms remain unclear. This study aimed at investigating the anti-tumor activity of various HDAC inhibitors, IN-2001, using T47D human breast cancer cells. Moreover, the possible mechanism by which HDAC inhibitors exhibit anti-tumor activity was also explored. In estrogen receptor positive T47D cells, IN-2001, HDAC inhibitor showed anti-proliferative effects in dose-and time-dependent manner. In T47D human breast cancer cells showed anti-tumor activity of IN-2001 and the growth inhibitory effects of IN-2001 were related to the cell cycle arrest and induction of apoptosis. Flow cytometry studies revealed that IN-2001 showed accumulation of cells at $G_2$/M phase. At the same time, IN-2001 treatment time-dependently increased sub-$G_1$ population, representing apoptotic cells. IN-2001-mediated cell cycle arrest was associated with induction of cdk inhibitor expression. In T47D cells, IN-2001 as well as other HDAC inhibitors treatment significantly increased $p21^{WAF1}$ and $p27^{KIP1}$ expression. In addition, thymidylate synthase, an essential enzyme for DNA replication and repair, was down-regulated by IN-2001 and other HDAC inhibitors in the T47D human breast cancer cells. In summary, IN-2001 with a higher potency than other HDAC inhibitors induced growth inhibition, cell cycle arrest, and eventual apoptosis in human breast cancer possibly through modulation of cell cycle and apoptosis regulatory proteins, such as cdk inhibitors, cyclins, and thymidylate synthase.

• 품질경영학회지
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• 제33권4호
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• pp.75-87
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• 2005

Generally speaking, weapon system is defined as a combination of primary system and support system which are evaluated by capability and operational availability respectively. Recently comparison of total life cycle cost shows that logistic support system is proved to be more important than primary system. However, until now systematic approach to support system development has not been applied in the area of developing support system. We need to construct a universal metric for effectiveness of logistic support system and to cut out whatever activities or support elements which do not contribute to the metric. This paper describes a new approach based on system engineering approach to logistic support system and also classifies five factors of failure, stock-out frequency, administrative delay time, active repair time and logistic delay time that have influence on operational availability of logistic support system.

• 한국안전학회지
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• 제25권6호
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• pp.155-160
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• 2010

In this study, detailed assessment for durability performance were performed on the chloride protected concrete structures to investigate the effectiveness of chloride protection. And economical efficiency for the chloride protected concrete structures were studied by LCC(Life Cycle Cost) analysis. In the comparison result of the first section repair time, it was found that the chloride protected concrete structures was economical better than the non-protected concrete structures in the long term. According to the analysis result of the accumulated chloride concentration by used time and chloride ion concentration by depth, it can be seen that the permeation through time from chloride has increased two times in the chloride protected concrete structures.

• 한국전자통신학회논문지
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• 제15권5호
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• pp.791-798
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• 2020

근래의 무기체계에서 첨단기술이 차지하는 비중은 점차 커지고 있으며, 빠른 기술발전 속도로 인하여 부품의 수명주기가 단축되고 실정이다. 이에 반하여 무기체계는 소요제기단계에서 운영/유지단계까지 오랜 시간이 소모되는 특성이 있다. 이로 인하여, 불가피하게 획득 단계에서 주요부품의 단종이 발생된다. 부품단종은 양산 일정 지연의 지연을 유발할 수 있으며, 나아가 운영유지단계에서는 원활하지 못한 부품 공급으로 운용가용도(Operational Availability)에 나쁜 영향을 미치게 된다. 한편, 사업관리자는 설계, 생산, 운영단계의 총수명주기 비용을 최소화하면서 성능을 극대화할 의무가 있으며, 이를 위해서는 적절한 부품단종관리 계획을 수립하고 이행할 필요가 있다. 본 논문에서는 적절한 부품단종관리를 통하여 절감할 수 있는 회피비용 및 총수명주기비용을 통하여 부품단종관리의 효용성을 분석하였다.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2009년도 춘계학술대회 논문집
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• pp.1989-1992
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• 2009

Maintenance is classified preventive maintenance before performing equipment failure and corrective maintenance after performing equipment failure. In preventive maintenance, we may analyze the failure data to end from beginning of equipment and allocate maintenance method and calculate maintenance cycle quantitatively by the failure data analysis. So, it has a merit to reduce system maintenance cost and to operate effectively but, it require high cost in system introducing and continuous operation to end of system. In corrective maintenance, we may calculate MTTR(mean time to repair) quantitatively based on function failure time. it can be based on establishing maintenance system for operation efficiency. In this paper, we may reflect the MTTR for the onboard equipped in Tilting train to establish maintenance system for Tilting train operation efficiency.