• 한국양식학회지
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• 제18권3호
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• pp.142-146
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• 2005

이 연구에서는 홍합과 지중해담치 치패의 크기별 재 부착 과정을 관찰하고 재 부착시간, 부착률 및 생존율을 조사 비교하였다. 또한 주사전자현미경(SEM)을 이용한 홍합과 지중해담치 족사의 외부형태를 관찰하였다. 홍합 소형 치패(각고 $3{\sim}7mm$)의 새로운 족사 생성에 의한 재 부착은 족사 분리 7분 내에 100%의 재부착률 및 생존율을 보였으며 크기별로 재 부착 시간과 생존율에는 차이가 없었다. 중형치패(각고 25 mm)는 5시간 내에 85%의 재 부착률을 보인 이후 24시간동안 나머지 개체는 부착하지 않았으나 생존율은 24시간 동안 100%를 나타내어 소형치패가 중형치패에 비해 족사 분리 후 재 부착에 소요되는 시간이 빠르고 재 부착률도 높았다. 홍합(각고 28 mm)과 지중해 담치(각고 30 mm) 중형치패의 시간경과에 따른 재부착률 및 생존율은 5시간내에 각각 73%, 73%의 재 부착률을 보인 이후 24시간 동안 나머지 개체는 부착하지 않았고 생존율은 모두 100% 를 보였으며 지중해담치가 홍합보다 빠르게 재부착한 치패가 많았다. 주사전자현미경을 이용하여 관찰된 담치류 부착 족사의 외부 형태는 고착반, 부착줄기, 부착근으로 구분할 수 있었으며, 각고 $20{\sim}30mm$ 범위의 홍합과 지중해담치의 치패에서 부착 족사의 크기를 비교한 결과 고착반은 각각 장축 $2,392{\times}934{\mu}m$, 장축 $1,056{\times}614{\mu}m$, 부착줄기 $39{\mu}m,\;28{\mu}m$, 부착근 $58{\mu}m,\;83{\mu}m$로 나타나 홍합이 지중해담치에 비해 고착반의 면적이 넓고 부착줄기의 두께가 두터웠다. 고착반과 부착줄기를 잇는 부착근의 두께는 지중해담치가 홍합보다 다소 두텁지만 단조로운 형태인 반면, 홍합은 물결모방의 가지를 뻗어 고착반에 부착한 미세구조를 확인할 수 있어 참담치의 족사 부착력이 지중해담치 보다 강한 것으로 판단되었다.

• 대한기계학회논문집A
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• 제40권7호
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• pp.673-677
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• 2016

최근, 자연 모사를 이용한 연구가 활발히 진행되어 지고 있다. 그 중에서도 높은 접착력으로 인해 이동이 자유로운 도마뱀붙이가 각광받고 있다. 도마뱀붙이는 발바닥 표피에 계층적 구조를 가지고 있고, 이러한 구조로 인하여 높은 접착력을 가진다. 본 연구에서는 건식 접착 구조물에 금속 코팅 두께에 따른 접착강도 변화에 대한 연구를 수행하였다. 건식 접착 구조물 제작을 위한 마이크로 몰드를 포토 리소그래피로 제작한 후, 고분자 폴리머인 PDMS를 사용하여 건식 접착 구조물을 제작하였다. 제작된 건식 접착 구조물의 금속 코팅은 플라즈마 스퍼터링을 사용하였다. 건식 접착 구조물의 접착력 실험은 Pure shear test방법을 통하여 평가하였다. 건식 접착 구조물에 인듐, 아연, 금을 코팅하였을 때 각각 4 nm, 8 nm 및 6 nm의 두께를 가질 때 접착 강도가 가장 우수한 결과를 보였다.

• 한국정밀공학회지
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• 제1권2호
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• pp.41-46
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• 1984

The machinability of calicium-deoxidized steel is studied in turning by being compared with that of Fe-Si deoxidized steel under a given set of cutting condition. Tool life, cutting force and cutting mechanism are examined on a few sorts of steel. It is found that adhesive layer "Belag" is developed on the cemented carbide tool and the peak value is observed at the cutting speed of 300m/min followed by gradual increase in the thickness of Belag with the increase of cutting speed. the maximum thickness of Belag is also shown at the feed of 0.3mm/rev. On the other hand, the tool life of carbide tool is more favorable than that of high speed steel (SKH 9) in cutting calcium- deoxidized steel. It is considered that the steel deoxidized with Ca-Si shows better machinability a little than that with Fe-Si. However, the cutting force and the shear angle of the former are similar to those of the latter in turning.n turning.

• 보존과학연구
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• 통권29호
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• pp.183-197
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• 2008

Paraloid B-72 of acrylic resins has been widely used as consolidant for bronze artifacts conservation. In previous study, xylene was appropriate for paraloid B-72 when bronze artifacts consolidated. In this study, we compared the coating properties of paraloid B-72 in various concentration levels. The surface before and after coating were observed by optical microscope and AFM. Thickness and adhesive strength of films were tested. For testing coating stability, we performed yellowing test and EIS. After these experiments, we concluded 15wt% paraloid B-72 was adequate concentration for bronze artifacts conservation when paraloid B-72 used in xylene as solvent. Because 15wt% paraloid B-72 has the lowest polarity and high hydrophobic.

• Nuclear Engineering and Technology
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• 제33권5호
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• pp.514-525
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• 2001

Optimum characteristics of digital X-ray sensor components were analyzed to develop intra- oral dental digital X-ray image sensor using indirect method. Parametric analysis was carried out to optimize the phosphor thickness and the fiber optic plate (FOP) coupling to charge coupled device (CCD). X-ray absorption and light diffusion in the phosphor layer were analyzed by the Monte Carlo method. Real time X-ray image was obtained with prototype X- ray image sensor using general CCD camera with 1∼10 Ip/mm resolution. It has been previously shown that large resolution degradation in X-ray images was caused by miss alignment of FOP to CCD and optical adhesive selection. In this study, we reported that X-ray image quality was greatly improved by using optimized characteristics of alignment device and phosphor thickness.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 춘계학술대회
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• pp.25-30
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• 2004

In this paper, the compensation of interfacial scatter due to adhesive layer and adherend thickness ratio variation was applied to improve measuring precision by calculating ultrasonic attenuation coefficient in the Al/Epoxy dissimilar bonded components. The optimum condition of theoretical value and experimental measuring accuracy by the ultrasonic method in the Al/Epoxy dissimilar bonded components have been investigated. From the experimental results, we proposed a measurement method of the interfacial crack lengths by the ultrasonic attenuation coefficient and discussed it.

• Journal of Forest and Environmental Science
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• 제31권2호
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• pp.119-125
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• 2015

This study examined the effects of rice straw steaming time and mixing ratio between rice straw and wood particle on the properties of mixed particle board from Acacia mangium Willd wood and rice straw. Rice straw and Acacia mangium Willd wood were collected in Hanoi, Vietnam. The particle board was three-layer particle board with the structural ratio of 1:3:1. The thickness, density and board size of the particle board were 18 mm, $0.7g/cm^3$, and $800{\times}800{\times}18$ (mm, including trimming), respectively. A resin mixture between commercial Urea-formaldehyde (U-F) adhesive and methylene diphenyl isocyanate (MDI) adhesive was used with a dosage of 12% for the core layer and 14% for the surface layer. In this experimental design, the steaming time for rice straw was 15, 30, 45, 60, and 75 minutes at $100^{\circ}C$. The rice straw-wood mixing ratio was 10, 20, 30, 40, and 50%. The results showed that both mixing ratio and steaming time affect the properties of the particleboard, but the mixing ratio has a stronger impact. A higher mixing ratio and a longer steaming time resulted in a better quality of particleboard. The optimal steaming time for rice straw was 46.12 minutes with the straw-wood mixing ratio of 29.85% with the following characteristics of the particle board: the modulus of rupture (MOR) of 14.64 MPa, internal bond strength (IB) of 0.382 MPa, thickness swelling (TS) of 8.83%, and board density of $0.7-0.7g/cm^3$.

• International Journal of Railway
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• 제1권2호
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• pp.72-81
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• 2008

This paper introduces a new steel jacketing method for reinforced concrete columns with lap splice and evaluates its performance by a series of axial tests of concrete cylinders. At first, 45 concrete cylinders were fabricated with varying the design compressive strengths of 21, 27 and 35 MPa and, then, the part of them was jacketed with two-split-steel jackets under lateral confining pressure. The parameters in the first test were the steel jacket's thickness and the existence of adhesive between steel and concrete surface. In the second test, whole steel jackets were used to wrap cylinders with lateral pressure. Also, a double-layer jacket consisted of two steel plates was introduced; a cylinder was jacketed by two steel plates one after another. The effect of the new method was verified through comparing the results of the compressive tests for plain and jacketed cylinders. The steel jacket built following the new method showed good results of increasing the compressive strength and ductility of the jacketed cylinders with respect to the plain cylinders. The thicker steel jackets showed the more increased compressive strength, and the ductility at failure depended on the welding quality on steel jackets. The adhesive between steel and concrete surface reduced the confining effect of the steel jackets. The whole jacket showed more ductile behavior than the two-split jackets. The double-layered jackets were estimated to possess an equal performance to that of a single steel jacket having the same thickness of the double-layered jacket. Finally, the experimental results were compared with the constitutive model of steel-jacketed concrete; which showed a good agreement between the experimental results and the models.

• 한국염색가공학회지
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• 제34권4호
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• pp.272-283
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• 2022

In this study, the flat-section monofilaments of PBT for artificial eyelashes was developed, and the physical properties of the circular cross-section of artificial eyelashes were compared and observed, and the main performance of the artificial eyelash prototype was observed through processing for artificial eyelashes. In addition, a satisfaction survey of the prototype was conducted through a survey of consumers and artificial eyelash operators. It was found that the bending stiffness value of the monofilaments increased significantly as the thickness increased. As a result of measuring the bending properties of the flat-section PBT monofilaments, the bending stiffness was significantly lower than that of the circular-section PBT specimens of the same thickness. The deformed cross-section PBT monofilaments with flat cross sections developed in this study showed a light weight factor of less than 50% compared to the existing circular cross-section PBT ones. The adhesive strength of the developed PBT artificial specimens was greater than that of the existing circular cross-section yarn. It was also observed that the curl stability over time was excellent. As a result of the consumer survey, it was possible to obtain more than 85% of positive answers in the case of consumer subjects, and it was possible to investigate that the satisfaction of the operator subjects was more than 80% compared to the existing round-section eyelashes.

• Restorative Dentistry and Endodontics
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• 제29권2호
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• pp.177-184
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• 2004

본 연구는 광중합형 상아질 접착제에서 광조사 시간의 증가가 접착제 표면의 미중합층에 대한 영향과 그에 따른 전단접착강도에 대해 연구하고자 120개의 치아를 아크릴 몰드에 식립한 후 상아질이 노출되도록 연마하였다. 3종류의 접착제 〔All Bond2 (AB2), One-Step (OS) and Adper Prompt (AP)〕를 40개 치아에 제조사의 지시대로 도포한 후 각각 다른 광조사 시간 (10, 20, 30 and 60sec)동안 광조사 하고 복합레진을 접착한 24시간 후 전단접 착강도를 측정하였다. 미중합층의 두께와 중합률은 슬라이드 글라스와 FT-NIR을 이용하여 FT-NIR spectrum에서의 peak height를 비교 측정하여 다음과 같은 결론을 얻었다. 1. 전단접착강도에서 AB2는 20초 이후 감소하고, AP는 30초까지 증가하였으며,OS는 차이를 보이지 않았다. 2. 미중합층 두께는 3가지 접착제 모두 유의성 있는 차이를 보이지 않았다. 3. 중합률에서 OS는 10초와 나머지군 사이에 유의성 있는 차이를, AP는 60초에서 유의성 있게 증가되고, AB2의 경우 차이를 나타내지 않았다.