• 한국공작기계학회논문집
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• 제11권4호
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• pp.1-5
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• 2002

A 110 m diameter aspheric metal secondary mirror for a test model of an earth observation satellite camera was fsbricated by ultra-precision single point diamond turning (SPDT). Aluminum alloy for mirror substrates is known to be easily machinable, but not polishable due to its ductility. A harder material, Ni, is usually electrolessly coated on an A1 substrate to increase the surface hardness for optical polishing. Aspheric metal secondary mirror without a conventional polishing process, the surface roughness of Ra=10nm, and the form error of Ra=λ/12(λ=632.8nm) has been required. The purpose of this research is to find the optimum machining conditions for reflector cutting of electroless-Ni coated A1 alloy and apply the SPDT technique to the manufacturing of ultra precision optical components of metal aspheric reflector.

• Macromolecular Research
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• 제17권12호
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• pp.995-1002
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• 2009

Luminescent polynorbornene (PNB)/quantum dot (CdSe@ZnS; QD) composite nanorods and nanotubes were successfully prepared using anodic aluminum oxide (AAO) membranes of various pore sizes as templates. To protect QDs with high quantum yield from quenching during the phosphoric acid treatment used to remove the AAO templates, chemically stable and optically clear norbornene-maleic anhydride copolymers (P(NB-r-MA)) were employed as a capping agent for QDs. The amine-terminated QDs reacted with maleic anhydride moieties in P(NB-r-MA) to form PNB-grafted QDs. The chemical- and photo-stability of QDs encapsulated with PNB copolymers were investigated by photoluminescence (PL) spectroscopy. By varying the pore size of the AAO templates from 40 to 380 urn, PNB/QD composite nanorods or nanotubes were obtained with a good dispersion of QDs in the PNB matrix.

• Corrosion Science and Technology
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• 제3권3호
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• pp.98-101
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• 2004

The corrosion behavior of Al-Fe coatings was studied in the wet-seal atmosphere of molten carbonate fuel cells (MCFC). Fe-8Al, Fe-16Al, Fe-25Al, Fe-36Al, and Fe-70Al (in at.%) specimens were tested in Li/K carbonate at $650^{\circ}C$ by a single cell test and an immersion test. In general, the corrosion resistance of the Al-Fe coatings was enhanced due to the formation of a protective $LiAlO_2$ layer. However, when the Al-Fe coatings didn't have sufficient content of aluminum enough for maintaining the protective layer, the corrosion resistance of the Al-Fe coatings was severely degraded by the growth of non-protective scales like $LiAlO_2$. The test results revealed that the aluminum contents in the coatings should be higher than 25 at.% in order to form and maintain the protective $LiAlO_2$ layers.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2001년도 춘계학술대회 논문집
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• pp.1125-1128
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• 2001

A 110mm diameter aspheric metal secondary mirror for a test model of an earth observation satellite camera was fabricated by ultra-precision single point diamond turning(SPDT). Aluminum alloy for mirror substrates is known to be easily machinable, but not polishable due to its ductility. A harder material, Ni, is usually electrolessly coated on an Al substrate to increase the surface hardness for optical polishing. Aspheric metal secondary mirror without a conventional polishing process, the surface roughness of Ra=10nm, and the form error of Ra=λ/12(λ=632nm) has been required. The purpose of this research is to find the optimum machining conditions for reflector cutting of electroless-Ni coated Al alloy and apply the SPDT technique to the manufacturing of ultra precision optical components of metal aspheric reflector.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 하계학술대회 논문집 Vol.4 No.2
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• pp.728-731
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• 2003

This paper deals with a flat type ultrasonic motor, which uses a longitudinal-bending multi mode vibrator of rectangular form. A linear ultrasonic motor was designed by combination of the first longitudinal and eighth bending mode, and the motor consisted of a straight aluminum alloy bar bonded with piezoelectric ceramic elements as a driving element. The geometrical dimensions of the rectangular aluminum vibrator were determined by Euler-Bernoulli theory ANSYS was used to analyze the resonance frequency and the displacement of the stator vibrator. The resonance frequency of the motor provides the elliptical motion. and ANSYS was used to analyze elliptical motion and elliptical trajectory of stator vibrator when thickness of piezoelectric ceramics was varied respectively 0.763, 1.526, 2.289[mm] and width of stator vibrator was varied respectively 16, 12, 8, 4[mm]. When thickness of piezoelectric ceramics was decreased, the displacement of the stator vibrator was increased. And when width of stator vibrator was decreased, the displacement of the stator vibrator was increased.

• Applied Microscopy
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• 제35권4호
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• pp.64-73
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• 2005

이 논문에서 한 결정체의 전위 결함에 형태를 결정짓는 인자들 (Burgers-벡터, Slip plane, 전위선 벡터)을, LACBED 방법과 전통적인 회절 빔 상 관찰에 의해, 어떻게 얻을 수 있는가에 대해 세세히 논의하였다. 이 방법은 기본적으로 Cherns과 Prestons의 규칙과 동역학적 회절이론에 입각한 공식에 의거한 LACBED 패턴 시뮬레이션이 따른다. 이 시뮬레이션 계산에서 필요에 따라 설정된 여러 근사들에 관해서도 역시 세세히 논의 하였다. 본 실험에 사용된 시료는 적적한 밀도로 분포된 전위 결함들을 많이 갖고 있는 순순 알루미늄이며, LACBED 실험에 적합한 것이다.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2017년도 춘계 학술논문 발표대회
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• pp.248-249
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• 2017

Red mud is an industrial by-product produced during the manufacturing aluminum hydroxide (Al(OH)₃) and aluminum oxide(Al₂O₃) from Bauxite ores. In Korea, approximately 2tons of red mud in a sludge form with 40~60% moisture content is produced when 1 ton of Al₂O₃ is produced through the Bayer process. An annual production of approximately 20tons are produced by company K, which is responsible for most of the domestic production. Therefore, in order to utilize Red Mud in the construction industry, this study evaluated the pore characteristics of ordinary portland cement mortar according to the red mud replacement ratio.

• Corrosion Science and Technology
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• 제4권1호
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• pp.33-38
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• 2005

Some feasibility studies are conducted to produce an advanced ceramic coating, which reveals superior chemical and mechanical strength, on metal base structure used in chemical plant. This advanced coating on metallic frame can replace ceramic delivery pipe and reaction chamber used in chemical plant, which are operated in hi-temperature and corrosive/erosive environment. An dual spraying is adopted to reduce the residual stress in order to increase the coating thickness and the residual stress is estimated by in-situ manner. Then new methodology is tried to form special coating of yttrium aluminum garnet(YAG), which reveals hi-strength and low-creep rates at hi-temperature, superior anti-corrosion property, hi-stability against Alkali-Vapor corrosion, and so on, on iron base structure. To verify the formation of YAG during thermal spraying, XRD(X ray diffraction) technique was used.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2009년도 춘계학술대회 논문집
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• pp.365-367
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• 2009

The use of aluminum alloy has been interested in the automotive industry, because of its specific strength. And hollow extruded billet is more attractive than solid extruded billet but its forming application has to be precisely processed to satisfy the product quality. In this research, the process design of forming of control arm for the vehicle was studied by press bending process with hollow extruded billet. The middle protrusion portions and the middle cylindrical cup were processed separately according to the analysis. It was concluded that a useful sequence is to bend the side flange and the middle protrusion portions firstly, and then to form the middle cylindrical cup.

• 한국철도학회논문집
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• 제3권2호
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• pp.92-99
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• 2000

Composites are very useful material for light train carbody due to its high specific strength and lightweight characteristics. The composites, called 3-D board, are developed with a special stitching method. In this process, the glass fiber fabrics of skin material and foam core material are stitched together with glass fiber thread. The glass thread in Z-axis turns into FRP form. The conventional delamination problem can be solved with 3-D sandwich structure. In addition, with the lower density of foam, the weight of the panel and the operation expenses can be highly reduced. To evaluate the usefulness of the 3-D board, the double-deck light train carbody is studied. The stress analyses are carried out under various loads and boundary conditions with FEM Code, ANSYS. On comparing with the aluminum carbody, 3-D board carbody can be reduced by about 2 ton for the total weight of carbody.