• Applied Microscopy
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• 제45권4호
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• pp.218-224
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• 2015

A technical overview on the various sample preparation methods for electron backscattered diffraction (EBSD) analysis is carried out. The mechanical polishing with colloidal silica finish, electro-chemical polishing, dual layer coating and ion beam milling are introduced for the common sample preparation methods for EBSD observation and some issues that are frequently neglected by the common EBSD users but should be considered to get a reliable EBSD data are discussed. This overview would be especially helpful to the people who know what EBSD technique is but do not get a reliable EBSD data because of difficulties in sample preparation.

• 펄프종이기술
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• 제48권2호
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• pp.68-74
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• 2016

Nanofibrillated cellulose (NFC) was prepared from cotton linter after electron beam irradiation to investigate its effects on the manufacturing efficiency of the NFC preparation and the property changes by the treatment. Mechanical device (Super Masscolloider) was used to prepare the NFC and its passing frequency for each NFC preparation was recorded. More electron beam irradiation resulted in less passing frequency. Alpha cellulose content, molecular weight, crystallinity index, and thermal decomposition behavior of each treatment were lowered by electron beam treatment (10 and 100 kGy) and grinding process. NFC films were prepared to investigate their mechanical properties. There were little changes in tensile properties of the NFC films.

• Composites Research
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• 제28권2호
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• pp.40-45
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• 2015

The purpose of the present work was to preparation and study of full biodegradable Eco-friendly bio-composites by using renewable resources. In this study, wheat protein isolate (WPI) films were formed by cross linking with resorcinol through solution casting method for packaging applications. By varying the resorcinol content (10, 20, 30, 40, and 50 wt %), its effect on mechanical properties of the wheat protein isolate film was measured. The addition of 20% resorcinol led to an overall increase in the tensile strength from 5.2 to 18.6 MPa and modulus increase from 780 to 1132 MPa than WPI films. The % elongation was increased from 2.8 to 9.05 when compared to unmodified WPI film. A thermal phase transition of the prepared WPI was assessed by means of DSC. FTIR is evident that the characteristic WPI spectral IR bands shifted on cross-linking with resorcinol.

• 대한기계학회논문집A
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• 제34권12호
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• pp.1785-1791
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• 2010

중합효소 연쇄반응(PCR)을 수행하려면 세포 용해(cell lysis)와 DNA추출(DNA purification)과정이 포함된 시료 전처리 과정을 거쳐야 한다. 종래의 시료 전처리 과정은 계면활성제와 같은 세포용해 버퍼를 이용하거나 열 또는 전기적 방법으로 세포막 파열을 유도하여 세포벽을 깬 후에 잔여물 처리과정을 거쳐 DNA를 추출하게 된다. 본 연구에서는 마이크로 비드와 PDMS 기둥을 이용한 필터가 있는 시료 전처리용 바이오칩을 설계 및 제작하였다. 또한 제작된 바이오칩을 사용하여 $80^{\circ}C$에서 2분간 세포용해를 수행하고 DNA를 추출하였다. 칩에서 전처리과정을 거친 시료내의 DNA농도와 순도를 측정하고 DNA PCR과 겔 전기영동을 통해 시료 전처리용 바이오칩의 성능을 평가하였다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2004년도 춘계 학술발표회 제16권1호
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• pp.216-219
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• 2004

Due to the recent amazing achievements in nano technology. preparation of cement nano particles by mechanical method are examined to improve their properties. The experimental results show that the particle size after 3 hr milling were about 500nm. The SEM photographs of specimens also reveal that average sizes of cement particles are gradually decreased by milling time. And in the TG/DSC, influence of the alcohol is showed strongly. The value of TG of the crushed cement was larger than that of the non-crushed cement. That is also judged to be cause the alcohol.

• 대한금속재료학회지
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• 제48권8호
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• pp.730-740
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• 2010

Aluminum, magnesium, titanium and high Mn steel are difficult to use in electron backscatter diffraction (EBSD) sample preparation due to the formation of an oxidation layer under conventional polishing. Alcohol-based polishing with colloidal silica suspension was introduced for these delicate samples. A hard particle-embedded sample was analyzed successfully using mechanical polishing. Ion-milling was effective in removing oxidized, deformed and transformed layers after mechanical polishing and was able to reduce artifacts significantly. The microstructure of a cross-section of a thin copper film was evaluated by attachment of a dummy to the film for mechanical polishing.

• Elastomers and Composites
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• 제50권1호
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• pp.35-48
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• 2015

Polyhedral oligomeric silsesquioxane (POSS) is an important inorganic-organic hybrid material with a three-dimensional structure. Polyurethane (PU) is a widely applied polymer that has versatile properties with the change of two phase structure. When POSS is incorporated into PU by physical or chemical methods, many properties can be greatly improved, such as mechanical properties, thermal stability, biodegradation resistance, and water resistance. This paper reviews the recent progress in preparation, structure, and performance of POSS-modified polyurethane from the viewpoint of physical blending and chemical modification.

• 대한치과의사협회지
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• 제57권7호
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• pp.380-391
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• 2019

In recent years, with the introduction of various restorative materials, restorations using CAD/CAM equipment have been increasing in the esthetic dentistry. The critical steps in the fabrication of indirect restorations with CAD/CAM equipment are proper cavity preparation and making accurate impressions. The process of tooth preparation for CAD/CAM restoration should include a mechanical understanding of milling. In addition, during tooth preparation, the clinician should be familiar with additional equipment and techniques for obtaining the convenience. In order to obtain an accurate oral scan, the clinician should understand the limitations of the oral scan and be skilled at techniques for obtaining a successful image when making oral scans. This article focused clinical guidelines for the preparation of CAD/CAM restorations and introduced clinical methods for making successful impression of oral scans in narrow and deep tooth cavity areas.

• 대한소아치과학회지
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• 제32권1호
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• pp.164-173
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• 2005

교합면 치아우식 예방을 위한 치면열구전색제 도포시 열구내 유기물, 치태, 법랑질 잔사 등을 제거하여 전색제의 유지율을 증가시키고자 기계적 삭제 방법이 소개되었다. 기계적 삭제방법을 사용할 경우 산부식 방법만을 사용하였을 때와 비교하여 치면열구전색제의 열구 침투도 및 미세누출정도의 차이는 임상적인 측면에서 중요하다. 따라서 이 연구에서는 기계적 삭제방법(소와열구 삭제 후 산부식)과 산부식 방법을 시행한 후, 각각 unfilled sealant와 filled sealant를 처치하고 이들 치면열구전색제의 열구 침투도와 미세누출 정도를 측정하였다. 교정치료를 목적으로 발거된 사람의 소구치 60개를 실험재료로 사용하였으며 그중 30개는 산부식 처리하고 나머지 30개는 소와열구의 기계적 삭제와 산부식 처리를 시행한 후 각각의 방법에서 15개는 unfilled sealant로 나머지 15개는 filled sealant로 수복하였다. Thermocycling($5^{\circ}C$와 $55^{\circ}C$ 1200회)을 시행하고 5% methylene blue 용액에 24시간 보관하였다가 각각의 치아를 근심소와와 원심소와에서 협설 방향으로 절단하여 120개의 절단면을 얻었다. 각 절단면을 Measurescope으로 관찰한 결과, 기계적 삭제 방법은 산부식만을 시행한 경우에 비하여 unfilled sealant와 filled sealant 모두 열구 침투도를 증가시켰다(P < 0.05). 기계적 삭제 방법을 사용한 경우 산부식 방법만을 사용하고 unfilled sealant로 수복한 경우에 비하여 미세누출이 적었고(P < 0.05), 산부식 방법만을 사용하고 filled sealant로 수복한 경우와는 미세누출에 차이가 없었다. Unfilled sealant와 filled sealant는 기계적 삭제 방법을 사용한 경우와 산부식 방법만을 사용한 경우 모두 열구 침투도나 미세누출에 있어서 유의한 차이가 없었다. 이상의 결과로 보아 치면열구전색제 도포 시 열구 침투도가 우수하고 미세누출이 적은 기계적 삭제 방법과 물리적 성질이 우수한 filled sealant의 사용이 바람직하다고 생각된다. 그러나 미세누출에 있어 교합력을 고려한 실험이나 장기간의 임상실험이 필요할 것이다.

• Elastomers and Composites
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• 제41권1호
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• pp.3-9
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• 2006

전분/PVA 블렌드의 기계적 물성에 영향을 미칠 수 있는 인자들을 고려하여 최적화 조건을 조사하였다. 통계적 방법인 다중혼합물 최적법을 사용하였으며, UTM과 인열 강도계를 통하여 블렌드의 인장강도, 파단신율, 초기모듈러스, 인열강도의 측정 결과를 분석하여 전분/PVA 블렌드의 제조 최적 조건을 결정하였다. 최적화 상태의 전분/PVA 블렌드는 농업용 필름의 기계적 물성 중 파단신율을 제외한 나머지 물성이 목표치와 같거나 조금 상회하는 수준을 나타내었다.