• 한국복합재료학회:학술대회논문집
• /
• 한국복합재료학회 2000년도 춘계학술발표대회 논문집
• /
• pp.20-25
• /
• 2000

In order to study the impact fracture behavior of brittle materials, a steel-ball-impact experiment was Performed. Five kinds of materials were used in this study : soda-lime glass plates, glass/epoxy prepreg-one layer-bonded and unbonded glass plates, glass/epoxy prepreg-three layers-bonded and unbonded glass plates. Fracture patterns, the maximum stress and absorbed fracture energy were observed according to various impact velocities 40-120m/s. With increasing impact velocity, ring crack, cone crack, radial crack and lateral crack took place in the interior of glass plates. The generation of such cracks was largely reduced with glass/epoxy prepreg coating. Consequently, it is thought that the characteristics of the dynamic Impact fracture behavior could be evaluated using the absorbed fracture energy and the maximum stress measured at the back surface of glass plates.

• Composites Research
• /
• 제14권1호
• /
• pp.15-21
• /
• 2001

고강성 카본 섬유 복합재료의 높은 비강성을 이용하여 가압 롤러를 설계·제작하였다. 롤러 제작을 위한 최적의 적층 순서는 유한요소해석을 통해 얻어졌으며, 고무코팅층의 형상은 롤러의 축 길이를 따라 필름에 가해지는 균일 압력에 대해 계산되어진 변형에 근거하여 결정하였다. 제작된 가압 롤러의 정적 변형을 해석결과와 실험적으로 비교하였으며, 그것의 동적 독성은 진동 시험을 통하여 측정하였다.

• 한국펄프종이공학회:학술대회논문집
• /
• 한국펄프종이공학회 2004년도 춘계학술발표논문집
• /
• pp.56-65
• /
• 2004

The Asia Pacific papermaking giants are China, Japan and Korea followed by Indonesia. The strong trends in recent years have been the move to alkaline/neutral sizing which has assisted the move from kaolin and talc as the major filler minerals to ground calcium carbonate and precipitated calcium carbonate. Kaolin remains important as a constituent in many coating formulations and Chinese-sourced talc, due to its brightness and price will remain important especially in paper filler minerals. The need for ever increasing printing surface quality and continuing efforts by the paper manufacturers to keep costs under control will ensure minerals in papermaking will continue to be a dynamic subject in the years ahead.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2002년도 추계학술대회논문집
• /
• pp.646-651
• /
• 2002

The flow field around a symmetrical airfoil in a uniform flow under the generation of noise was studied by experiments and numerical simulation. The experiments are conducted by visualizing the surface flow over the airfoil with a shear-sensitive liquid-crystal coating and by measuring the instantaneous velocity field around the trailing edge of the airfoil. The results indicate that the discrete frequency noise is generated when the separated laminar flow reattaches near the trailing edge of the pressure side and the turbulent boundary layer is formed over the suction side of the airfoil near the trailing edge. The periodic behavior of vortex formation was observed around the trailing edge and it persists further downstream in the wake. The frequency of the vortex formation in the wake was consistent with that of the discrete frequency noise.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 1997년도 추계학술대회 논문집 학회본부
• /
• pp.618-620
• /
• 1997

A $50{\times}50{\mu}m^2$ aluminum micromirror array is fabricated using shadow evaporation process. The fabrication process is very simple with use of shadow evaporation process, and the micromirror array has a high fill-factor. The static and dynamic characteristics such as deflection angle vs. applied voltage, step response, and frequency response are measured using a contact free optical measurement technique. The downward threshold voltage was 8 V, step response time was $13.5{\mu}s$ when 32 V step voltage applied, and a resonance observed at 11kHz. The lifetime of micromirror with anti-stiction coating was tested and micromirror operated successfully over 200 million cycles of touch-down operations.

• 한국농업기계학회:학술대회논문집
• /
• 한국농업기계학회 1996년도 International Conference on Agricultural Machinery Engineering Proceedings
• /
• pp.238-246
• /
• 1996

When the important structures or components of agricultural machinery are designed, the full-filed methods of stress analysis can provide enough information in order to obtain lighter weight and prevent failure. The photoelasticity has been applicated to solve many practical engineering problems. The coating method provides full-field information, enabling the engineers to determine the complete distribution of surface strains and directly highlighting severely strained areas, especially for the welded frames of agricultural machinery. A combined method of model and prototype for strain analysis of excavator has been successfully applied to improve design. A measuring and recording system controlled by micro-computer and application software for dynamic event was studied. It can be widely used in structural failure analysis under cyclical loading . Typical application concerned stress field of crack tip and failure analysis of some mechanical structures are introduced are in roduced briefly in this paper.

• Korea-Australia Rheology Journal
• /
• 제13권4호
• /
• pp.179-187
• /
• 2001

As part of continuing efforts to investigate nonlinear dynamics and stability of film casting process, our earlier results obtained by Lee et al. (2001b) have been extended in the present study to cover the film casting of both extension thickening and extension thinning fluids. The same instability mechanism and draw resonance criterion previously derived have been found valid here, and a rather complex dynamic behavior of film width in contrast to that of film thickness has also been confirmed. The effect of fluid viscoelasticity on draw resonance, however, exhibits opposite results depending on whether the fluid is extension thickening or thinning, i.e., it stabilizes film casting in the former while destabilizing in the latter. The encapsulation extrusion method which recently has been successfully employed to stabilize industrially important paper coating process, has been theoretically explained in the present study as to why such stabilization is possible.

• Bulletin of the Korean Chemical Society
• /
• 제30권2호
• /
• pp.297-301
• /
• 2009

We have developed the yttrium oxide (YNP) or ytterbium oxide (YbNP) nanoparticle/polymer matrices for the size-dependent separation of DNA ranging from 100 bp to 9,000 bp. High separation efficiency (> $10^6$ plates/m) and the baseline resolution for various DNA standards (100 bp, 500 bp, and 1 kbp DNA ladder) were obtained in 10 min with these matrices. The effects of concentrations of both polyethylene oxide (PEO) and nanoparticles were investigated and the highest performance was obtained at 0.02% PEO with 0.02% YNP or YbNP. Similar sieving power for both YNP and YbNP matrices was observed probably due to the similar sizes of nanoparticles, resulting in the formation of comparable sieving networks for DNA separation. For the reduction of electrosmotic flow, either dynamic or permanent coating of the capillary inner wall was compared and it turned out that PEO was superior to polyvinylpyrrolidone (PVP) or polyacrylamide (PAA) for better separation efficiency.

• 한국정보디스플레이학회:학술대회논문집
• /
• 한국정보디스플레이학회 2009년도 9th International Meeting on Information Display
• /
• pp.1272-1273
• /
• 2009

We demonstrate conformal phosphor coating and patterning methods on light emitting diodes (LEDs) using image processing based optofluidic maskless lithography (IP-OFML) system in microfluidic channels. IP-OFML allows a real-time detection and dynamic mask generation for packaging of randomly dispersed microchips. Our system detects each chip by considering rotation of the chip through image processing regardless of their arrangement error. Therefore, it precisely packages the chip making conformal polymer layer.

• KSBB Journal
• /
• 제13권2호
• /
• pp.125-132
• /
• 1998

Protein affinity membrane was prepared via the coating of chitosan gel on the porous flat polysulfone membrane surface, followed by the immobilization f the reactive dye (Cibacron Blue 3GA) to the chitonsan gel. The maximum protein binding capacity of affinity membrane was about 70${\mu}g/cm^2$ determined by the batch adsorption experiments of human serum albumin (HSA). Using module of this membrane, the characteristics of protein chromatography were investigated through the experiments of elution and frontal chromatography of HSA. This membrane module promises as a chromatography column, since it represented a lower pressure drop and a greater reproducibility. The protein separation ratio was significantly influenced by the flow rate of mobile phase and the injection quantity of HSA. The dynamic protein binding capacity of module decreased from the equilibrium binding capacity with increasing flow rate and approached the value of 15 - 20 ${\mu}g/cm^2$ for flow rates above 6 mL/min.