• 생명과학회지
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• 제20권12호
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• pp.1784-1791
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• 2010

본 연구에서는 AGS 인체 위암세포에서 톳 에탄올 추출물(EHF)의 항침윤성과 tight junctions (TJs)의 tightening과의 관계를 조사하였다. EHF에 의한 AGS 위암세포의 증식억제와 연관된 세포이동성 및 침윤성의 감소는 transepithelial electrical resistance의 증가와 연계된 Js의 tightness 증가와 연관성이 있었다. EHF는 matrix metalloprotease (MMP)-2 및 -9의 활성을 억제하였으며, 이는 MMPs의 mRNA 및 단백질 발현 감소에 의한 것이었으나 tissue inhibitor of metalloproteinase (TIMP)-1 및 -2의 mRNA 발현은 증가시켰다. 또한 EHF는 TJs의 주요 조절인자인 claudin family 단백질들(claudin-1, -3 및 -4)의 발현을 감소시켰으며, insulin like growth factor-1 receptor 단백질은 감소된 반면 thrombospondin-1 및 E-cadherin의 발현은 증가되었다. 본 연구의 결과는 톳 추출물이 암의 전이를 효과적으로 억제하는 효능이 있음을 보여주는 결과이다.

• 자원리싸이클링
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• 제17권5호
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• pp.11-18
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• 2008

본 연구에서는 고로슬래그 미분말 혼입률에 따른 라텍스개질 콘크리트의 역학적 특성과 탄산화 특성을 평가하였다. 이를 위해 라텍스 혼입률 변화(0%, 15%)와 고로슬래그 혼입률 변화(0%, 30%, 50%)를 실험변수로 하였으며, LMC와 BS-LMC의 특성분석을 위하여 압축강도, 황산, 염산에 대한 화학저항성 및 탄산가스에 의한 탄산화 촉진 시험을 실시하였다. 실험결과, 고로슬래그 혼입률이 30%일 경우 일반콘크리트와 동일한 강도발현 특성을 나타내었다. 고로슬래그 혼입율 50%의 조건은 탄산화에 의한 구조적 품질 저하가 예상되었으나 혼입률 30%이하에서는 일반콘크리트보다 우수한 탄산화 억제 효과가 있는 것으로 평가되었다. 특히 황산 및 염산용액 침지에 따른 강도저하 문제는 라텍스를 혼입함으로써 저감할 수 있었으며 탄산가스에 의한 중성화 진행도 라텍스를 혼입함으로서 개선되는 것으로 나타났다.

• 대한기계학회논문집A
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• 제35권12호
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• pp.1663-1668
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• 2011

자동차 차체를 제작하는 프레스 금형의 가공공정 중 제품의 형태를 완성하는 드로잉 공정 및 불필요한 부분을 절단하는 트리밍 공정은 그 공정의 특성상 금형의 마모가 심하기 때문에 금형의 내마모성을 향상시키기 위한 표면경화처리가 요구되고 있다. 따라서 본 연구에서는 프레스 금형에 레이저 표면처리기술을 적용하기 위한 실험을 실시하였다. 드로잉 공정 및 트리밍 공정에 적합한 표면경화처리를 위해 다이오드 레이저를 이용하여 시험편의 평면부 및 모서리부를 열처리하였으며, 각각의 적정 열처리 조건을 도출하였다. 또한 시험편의 재료에 따른 열처리 특성을 비교하기 위해 구상흑연 및 편상흑연 주철을 사용하여 실험을 진행하였다. 실험 결과, 재료에 따른 열처리 특성에 차이가 있다는 것을 확인하였으며, 적정 열처리된 조건에서의 경화부는 모재에 비하여 약 3배 정도의 경도상승을 나타내었다.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2000년도 춘계학술발표회 초록집
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• pp.1-1
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• 2000

The results of the modification of metal materials treated by high temperature pulst:d plasma fluxes (HTlPPF) with a specific power of incident flux changing in the $(3...100)10^5{]\;}W/cm^2$ range and a pulse duration lying from 15 to $50{\;}\mu\textrm{s}$ have been presented. The results of HTPPF action were studied on the stainless steels of 18Cr-l0Ni, 16Cr- 15Ni, 13Cr-2Mo types; on the structural carbon steels of (13...35)Cr, St. 3, St. 20, St. 45 types; on the tool steels of U8, 65G, ShHI5 types, and others; on nickel and high nickel alloy of 20Cr-45Ni type; on zirconium- and vanadium-base alloys and other materials. The microstructure and properties (mechanical, tribological, erosion, and other properties) of modified materials and surface alloying of metals exposed to HTPPF action have been investigated. It was found that the modification of materials by HTPPF resulted in a simultaneous increase of several properties of the treated articles: microhardness of the surface and layers of 40...60 $\mu\textrm{m}$ in depth, tribological characteristics (friction coefficient, wear resistance), mechanical properties ({\sigma_y}, {\;}{\sigma_{0.2}}.{\;}{\sigma_r}) on retention of the initial plasticity ($\delta$), corrosion resistance, radistanation erosion under ion irradiation, and others. The determining factor of the changes observed is the structural-phase modification of the near-surface layers, in particular, the formation of the fine cellular structure in the near-surface layers at a depth of $20{\;}{\mu\textrm{m}}$ with dimension of cells changing in the range from 0.1 to $1., 5{\;}\mu\textrm{m}$, depending on the kind of material, its preliminary treatment, and the parameters of plasma fluxes. The remits obtained have shown the possibility of purposeful surface alloying of metals exposed to HTPPF action over a depth up to 20...45 $\mu\textrm{m}$ and the concentration of alloying element (Ni, Cr, V) up to 20 wt.%. Possible industrial brunches for using the treatment have been also considered, as well as some results on modifying the serial industrial articles by HTPPF.

• 한국해양공학회지
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• 제23권3호
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• pp.30-34
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• 2009

Oil hydraulic piston pumps are being extensively used in the world, because of simple design, light weight and effective cost etc. An oil hydraulic pump is likely to have serious problems of high leakage, friction and low energy efficiency according to large time use. In the oil hydraulic piston pumps the clearance between the valve block and piston plays an important role for volumetric and overall efficiency. In this paper, the wear property of the SACM645 material used the hydraulic piston pump has been work out by experimentation with variable heat treatment. To investigate the effect according to the piston surface condition, seven different types specimen were prepared. From the wear test results, induction hardening and nitration were definitely superior to the others. On the whole, nitration was estimated for high strength material to wear resistance.

• The Plant Pathology Journal
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• 제25권1호
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• pp.6-12
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• 2009

Snow molds are the most important winter diseases of turfgrass in the United States and Canada. Eight isolates of three snow mold fungal species (three isolates of Typhula ishikariensis, three of T. incarnata, and two of Microdochium nivale) were collected from infected turfgrasses on golf courses. The isolates were evaluated for their relative aggressiveness on three cultivars (L-93, Penncross, and Providence) of creeping bentgrass (Agrostis palustris) under the same controlled conditions. Four plant ages (15, 19, 23 and 27 week-old plants from germination to inoculation) were evaluated for their susceptibility to the three pathogens and for the recovery of the plants. Regardless of age or cultivar of the host plant, M. nivale was found to be more aggressive and faster to infect and colonize than Typhula species. After three weeks recovery, M. nivale-inoculated plants showed higher disease severity than plants inoculated with the two Typhula species. Plants infected by Typhula species displayed no significant difference in disease severity. As creeping bentgrass plants get older, the severity of disease caused by three snow molds gradually decreases. This effect was observed in all cultivars tested, suggesting expression of age-related resistance as the bentgrass plants matured.

• International Journal of Quality Innovation
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• 제6권3호
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• pp.56-69
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• 2005

There have been growing concerns about whether proper measures are in place to ensure the delivery of quality services and the operations in research and educational institutions. This paper describes various quality models and discusses their relevance into the total quality concepts and quality management systems (QMS) in education. It then illustrates how a QMS and the accompanied quality manual be developed in a research and educational institution using the Centre for Enterprise Research Integration (ERI) at The University of the West Indies, Trinidad as a case. Through personal interviews with the $Centre{\square}s$ personnel, views on the operations and determinants of the QMS were acquired. Results showed that the people's resistance to changes, conflicts on academic freedom, and difficulties on measuring performance were the obstacles to QMS implementation. People involvement and proper communication are determinants of QMS implementation. The system also rests on having a tailored quality manual that entails the documentation of processes and procedures for ascertaining the delivery of quality services and operations in the Centre. The development of quality manual is briefly described in the paper.

• International Journal of Quality Innovation
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• 제6권2호
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• pp.131-146
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• 2005

There have been growing concerns about whether proper measures are in place to ensure the delivery of quality services and the operations in research and educational institutions. This paper describes various quality models and discusses their relevance into the total quality concepts and quality management systems (QMS) in education. It then illustrates how a QMS and the accompanied quality manual be developed in a research and educational institution using the Centre for Enterprise Research Integration (ERI) at The University of the West Indies, Trinidad as a case. Through personal interviews with the Centre's personnel, views on the operations and determinants of the QMS were acquired. Results showed that the people's resistance to changes, conflicts on academic freedom, and difficulties on measuring performance were the obstacles to QMS implementation. People involvement and proper communication are determinants of QMS implementation. The system also rests on having a tailored quality manual that entails the documentation of processes and procedures for ascertaining the delivery of quality services and operations in the Centre. The development of quality manual is briefly described in the paper.

• Safety and Health at Work
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• 제6권1호
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• pp.46-55
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• 2015

Background: Small and medium enterprises (SMEs) are often the main pillar of an economy. Minor accidents, ergonomics problems, old and outdated machinery, and lack of awareness have created a need for implementation of safety practices in SMEs. Implementation of healthy working conditions creates positive impacts on economic and social development. Methods: In this study, a questionnaire was developed and administered to 30 randomly chosen SMEs in and around Mumbai, Maharashtra, and other states in India to evaluate safety practices implemented in their facilities. The study also looked into the barriers and drivers for technology innovation and suggestions were also received from the respondent SMEs for best practices on safety issues. Results: In some SMEs, risks associated with safety issues were increased whereas risks were decreased in others. Safety management practices are inadequate in most SMEs. Market competitiveness, better efficiency, less risk, and stringent laws were found to be most significant drivers; and financial constraints, lack of awareness, resistance to change, and lack of training for employees were found to be main barriers. Conclusion: Competition between SMEs was found to be major reason for implementation of safety practices in the SMEs. The major contribution of the study has been awareness building on safety issues in the SMEs that participated in the project.

• 한국정보시스템학회지:정보시스템연구
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• 제30권3호
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• pp.137-158
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• 2021

Purpose This study aims to investigate which factors have impact on the acceptance intention of new electronic ID. For the empirical analysis, this study utilized PLS-SEM after collecting 385 survey data, and analyzed relations between each factors. Design/methodology/approach This study made a design of the research model by integrating the factors deducted from the Unified Theory of Acceptance and Use of Technology with the factors deducted from the Risk Factors. Findings The results are as follow; First, of the UTAUT factors, Performance Expectancy, Effort Expectancy and Social Influence and has positive impact on Acceptance Intention, but Facilitating Conditions doesn't have meaningful impact on Acceptance Intention. Second, of the Risk factors, Innovation Resistance has negative impact on Acceptance Intention, but Perceived Risk dose not have meaningful impact on Acceptance Intention. Finally, regulatory effect of the Promotion Focus, Prevention Focus and Gender has regulatory impact to Acceptance intention. It is expected that the implications of this study enables government effectively to offer new electronic ID.