• 제목/요약/키워드: Micro strength

검색결과 1,201건 처리시간 0.032초

마이크로플루트 골판지생산을 위한 실험용 코루게이터의 최적 운전조건 탐색 (Investigation on the Lab Scale Corrugator's Optimum Operating Conditions for Making Microflute Corrugated Paperboards)

  • 조용민;엄기증
    • 펄프종이기술
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    • 제39권2호
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    • pp.54-59
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    • 2007
  • Cereal, computer software, wine, small appliances, and fast foods are examples of products that have switched from folding carton to microflute corrugated paperboard. Microflute corrugated paperboards have their unique wonderful packaging characteristics that are driving forces for people to use more and more. Good strength property, excellent shock absorbing ability, and beautiful outer appearance of microflute corrugated paperboards go hand and hand with their environmental advantages. It is known that physical properties of microflute corrugated paperboards depend on not only properties of base paper but corrugator operating conditions. This study was carried out to investigate on the corrugator's optimum operating conditions for making micro flute corrugated paperboards. Lab-scaled micro flute corrugator was installed and run with systematic changes of operation conditions to investigate the effects of operation conditions on physical properties of micro flute corrugated paperboards.

SLS형 쾌속조형기를 이용한 미세구조 몰드 제작 (Fabrication of micro structure mold using SLS Rapid Prototyping)

  • 유홍진;김동학;장석원;김태완
    • 한국산학기술학회논문지
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    • 제5권2호
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    • pp.186-190
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    • 2004
  • Nano size 몰드의 제작은 X-ray lithography 방법을 이용하여 몰드를 제작하고, micro size의 경우 Deep UV lithography 방법을 이용하여 몰드를 제작하고 있다. 본 연구에서는 SLS(Selective Laser Sintering)형 RP(Rapid Prototyping System)을 이용하여 미세구조 몰드를 제작하였으며, 패턴의 깊이는 400 ㎛까지 구현하였다. 제작된 몰드의 강도와 내열성을 높이기 위하여 전해도금을 이용하여 몰드의 표면에 Ni를 300 ㎛생성 시켰다.

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Some Micro-discharge Characteristics of the cells in ac-PDP

  • Son, Jin-Boo;Lee, Sung-Hyun;Lee, Dong-Hyun;Kim, Young-Dae;Cho, Jung-Soo;Park, Chung-Hoo
    • 한국정보디스플레이학회:학술대회논문집
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    • 한국정보디스플레이학회 2000년도 제1회 학술대회 논문집
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    • pp.103-104
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    • 2000
  • Voltage transfer curves have been used for analyzing the micro-discharge characteristics of cells in ac-PDP. This paper deals with the effect of working gas species, pressure and frequency of applied voltage on the micro-discharge characteristics. Using the mixture gases of He+Xe or He+Ne+Xe, wall voltage steeply varied compared with only He gas, and also voltage margin increased. Discharge voltage and voltage margin increased with increasing Xe percentage, and also wall voltage more steeply varied. In addition, the variation of effective wall capacitance which is significantly dependent on the discharge strength is discussed.

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Numerical simulation and experimental study of quasi-periodic large-scale vortex structures in rod bundle lattices

  • Yi Liao;Songyang Ma;Hongguang Xiao;Wenzhen Chen;Kehan Ouyang;Zehua Guo;Lele Song
    • Nuclear Engineering and Technology
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    • 제56권2호
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    • pp.410-418
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    • 2024
  • Study of flow behavior within rod bundles has been an active topic. Surface modification technologies are important parts of the design of the fourth generation reactor, which can increase the strength of the secondary flow within the rod bundle lattices. Quasi-periodic large-scale vortex structure (QLVS) is introduced by arranging micro ribs on the surface of rod bundles, which enhanced the scale of the secondary flow between the rod bundle lattices. Using computational fluid dynamics (CFD) and water experiments, the flow field distribution and drag coefficient of the rod-bundle lattices are studied. The secondary flow between the micro-ribbed rod-bundle lattice is significantly enhanced compared to the standard rod-bundle lattice. The numerical simulation results agree well with the experimental results.

세라믹 박판의 접착 강도 측정 (Measurement of Adhesion Strength for Ceramic Sheet)

  • 허용학;김동일;김동진;이경호;김동진
    • 대한기계학회:학술대회논문집
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    • 대한기계학회 2007년도 춘계학술대회A
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    • pp.1798-1802
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    • 2007
  • Adhesion strength of single layer ceramic capacitor sheet was measured using a peel testing system developed in this study. The peel test specimens with various dimensions were prepared from the ceramic sheet cast on the PET film. In peel test, the sheet specimen was adhered on the glass jig floating on the liquid media, which was designed to minimize the friction, and the specimen was then pulled up by micro-actuator. During the separation of the sheet from the PET film, peel force was measured. To normalize the testing condition, 3 different widths of the specimen were selected: 5, 10 and 20 mm. was used Furthermore, testing speed effect was investigated in this study. From the resullts using various testing conditions, the standard method for the peel strength testing may be suggested. Based on the testing condition, effect of peel angle on the strength was experimentally examined. It was found that the adhesive strength for the ceramic sheet is nearly identical, irrespective of the specimen width ranged from 5 to 20 mm, while the adhesive strength was increased with increasing testing speed. Furthermore, the strength was shown to be dependent on the peel angle.

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Effect of graphite particulate on mechanical properties of glass fibre reinforced composite

  • Bhattacharjee, Antara;Roy, Kanchan;Nanda, B.K.
    • International Journal of Aerospace System Engineering
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    • 제7권1호
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    • pp.16-20
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    • 2020
  • The recent trend is increasing towards the usage of polymer matrix composites since they have a wide variety of applications. They have applications in the field of aircraft and space industry, sporting goods, medical devices, marine and automotive applications and also in commercial usage. The most commonly used fibre-reinforced polymer matrix composite is Glass fibre reinforced epoxy (GFRE) composite which is used in aviation, sports and automotive industries. However, the strength of GFRE composites is not adequate for structural applications. Therefore, the current research focuses on increasing the strength of GFRE composites by reinforcing with micro Graphite (Gr) particulates. The Gr used is an ultra-fine powder with particle size 250 ㎛. Gr is known to have good wear resistance, thermal conductivity and can operate at high temperatures. Gr particulates are mixed with the epoxy matrix in various weight ratios. Hand-lay technique is used for fabricating the composites. Mechanical properties such as tensile strength, elongation, compressive strength and flexural strength are obtained experimentally to study the effect of change in Gr content (0-5 wt. %). The tests were done as per ASTM standards.

Removal of superficial dentin surface to restore decreased bond strength caused by sodium hypochlorite

  • Song, Mi-Yeon;Hwang, Ho-Keel;Jo, Hyoung-Hoon
    • 대한치과의사협회지
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    • 제53권12호
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    • pp.958-966
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    • 2015
  • Objective: Sodium hypochlorite (NaOCl) decreases the bond strength of resin composite. The purpose of this study was to compare the effect of antioxidant and superficial dentin surface removal on the microtensile bond strength of NaOCl-treated dentin. Materials and Methods: Twenty non-carious human third molars were used in this study. The dentin surfaces were treated with 5.25% NaOCl for 10 min, followed either by treatment with 10% ascorbic acid or superficial dentin surface removal. Two-step self-etch adhesive and resin composite were used for restoration. The bonded specimens were subjected to the microtensile bond strength test. Statistical analysis was performed using one-way analysis of variance (ANOVA) and Tukey's test (p < 0.05). Results: The bond strength after removal of the superficial dentin surface following NaOCl irrigation was similar to that in the control group. The group treated with 10% ascorbic acid demonstrated significantly higher bond strength than the other groups. Conclusion: NaOCl irrigation-induced reduction in dentin bond strength could be recovered by either treatment with 10% ascorbic acid or simple removal of the superficial dentin surface.

무기질계 지반주입재의 내구성 및 친환경적 특성에 관한 연구 (A Study on the Durability and Environmentally Friendly of Inorganic Grouting Material)

  • 천병식;박덕흠;강형남;도종남
    • 한국지반환경공학회 논문집
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    • 제9권5호
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    • pp.37-43
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    • 2008
  • 무기질계 주입재는 지반개량 재료로서 기존의 물유리계 재료를 사용할 경우 발생하는 용출현상 및 강도저하를 보완한 시멘트계 급결재와 무기질계 초미립자를 주원료로 하는 순수 무기질 재료를 사용한 것으로서, 시공 후 내구성 및 강도가 우수하고 주입재의 용출 현상이 발생하지 않아 환경오염 문제가 거의없는 영구적인 차수 및 보강에 적합한 친환경적인 재료이다. 본 연구는 지반개량 재료로서 급결성 시멘트계 재료와 순수 무기질 주입재를 주원료로 배합된 MIS(Micro Injection-process System)와 기존에 많이 쓰여지고 있는 물유리계 주입재인 SGR의 내구성 및 친환경적특성을 일축압축강도시험, 내화학성시험, 어독성시험, 화학성분 분석 등의 실험으로 비교 분석 하였다. 일축압축 시험결과 재령 28일 강도는 MIS가 SGR재료에 비해 1.7배 크게 발현 되었고, 재령 40일 이후 SGR재료는 강도가 저하하는 반면 MIS는 지속적으로 증가하는 경향을 보였다. 내화학성시험 결과 MIS의 길이변화율이 물유리계주입재에 비해 10배~25배 작게 나타났다. 그리고, 어독성시험 결과 MIS가 물유리계주입재에 비해 친환경적임이 증명되었고, 화학성분 분석 결과 MIS 용출액이 물유리계주입재의 용출액에 비해 $Cr^{6+}$, Pb, Si 성분이 적게 검출됨을 확인할 수 있었다. 따라서, MIS 주입재는 기존의 SGR 주입재에 비해 고강도로 공기단축 및 기초지반의 구조적 안정성이 우수하며 친환경적이라 지하수오염 등의 문제도 적을 것으로 판단된다.

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당류계 초지연성 혼화제를 사용한 시멘트 페이스트의 응결 및 미시구조 특성 (Setting and Micro-structures of the Cement Pastes Using Sugar-Based Super Retarding Agents)

  • 정영진;현승용;한준희;김종;한민철
    • 한국건축시공학회지
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    • 제23권6호
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    • pp.703-714
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    • 2023
  • 본 연구에서는 효율적인 콘크리트용 당류계 초지연제를 개발하기 위해 현재 시판되고 있는 당 성분의 물질들을 대상으로 이들의 종류 및 혼입률 변화에 따른 시멘트 페이스트의 응결지연 특성, 압축강도 발현 특성 및 미시구조 특성을 분석하고자 하였다. 당류계 초지연성 혼화제 중 백설탕, 슈가파우더 및 스테비오사이드를 사용할 경우 응결지연에 효율적인 것으로 나타났다. 슈가파우더 및 스테비오사이드를 제외한 여타 배합의 경우 Plain 대비 동등한 수준의 압축강도를 발휘하는 것으로 나타났다. 특히, 백설탕의 경우 0.2% 혼입시 재령 1일에서 강도가 발휘되지 않다가 재령 28일에서는 Plain과 비교하여 동등 이상의 강도를 발휘하는 것으로 나타났다. XRD, SEM 및 EDS 분석 결과, XRD를 통해 백설탕에 의한 C3S의 수화지연(응결 지연)을 확인하였으며, EDS의 정량 분석을 통해 추가적으로 확인할 수 있었다. 수화물의 유무는 SEM를 이용하여 존재를 확인하였다. 본 연구 범위에 한하여 콘크리트용 당류계 초지연성 혼화제로써 백설탕을 사용할 경우 응결지연 성능 및 압축강도 발현 성능에 효과적일 것으로 판단된다.

열간가압소결에 의해 제조된 AlN-hBN 복합재료의 마이크로 엔드밀링 절삭특성 비교와 공구마모에 관한 실험적 연구 (Experimental Investigations on Micro End-milling Cutting Characteristics Comparison and Tool Wear Behavior of AlN-hBN Composites Sintered by Hot-pressing)

  • 백시영;신봉철;조명우;조원승
    • 한국공작기계학회논문집
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    • 제17권4호
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    • pp.104-111
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    • 2008
  • The objective of this study is to evaluate micro end-milling characteristics and tool wear behavior of AlN-hBN composites. First, AlN based composites with hBN contents in the range of 10 to 20vol% were prepared by hot-pressing. Vickers hardness and flexural strength of the prepared composite specimens were measured and compared according to the vol% of hBN variations. Then, cutting force variations were measured and analyzed using a tool dynamometer during the micro end-milling experiments; and machined surface shapes and roughness were investigated using a 3D non-contact type surface profiler. After micro end-milling, worn tools were investigated using a tool microscope and SEM images. From the experimental results, it can be observed that the cutting forces decreased, and surface qualities were improved with increasing hBN contents. At low content of hBN, tool chipping was observed; and tool wear rate decreased with increasing hBN contents. The results of this study insist that proper machining conditions, including tool wear behavior investigation, should be determined for the micro end-milling of AlN-hBN composites for its further application.